Netter's Concise Orthopaedic Anatomy 2nd Edition

9 Leg/Knee • RADIOLOGY

AP radiograph of knee Lateral radiograph of knee

Patella Medial
femoral
Lateral condyle
femoral
condyle Tibial Trochlear Lateral
spines groove tibial
Lateral plateau
tibial Medial Patella (convex)
plateau tibial
plateau Sulcus Medial
Fibular terminalis tibial
head plateau
(concave)

Tibial
tubercle

Blumensaat’s line

Notch radiograph Sunrise radiograph
Tibial spines
Lateral Intercondylar Lateral
femoral
condyle notch patellar

Lateral facet
tibial
plateau Medial Lateral Medial
femoral femoral patellar
condyle condyle facet

Medial Trochlear groove Medial femoral
tibial condyle
plateau

RADIOGRAPH TECHNIQUE FINDINGS CLINICAL APPLICATION
KNEE
AP Supine; beam at 90° Medial/lateral compartments; Femoral condyle, tibial plateau/
varus/valgus deformity spine, patella fx, OCD, osteo-
Lateral Supine; 30° flexion arthritis (weight-bearing)
Patellofemoral compartment
Axial/ Prone; knee 115° flex; beam Fractures, quadriceps/patellar
sunrise at patella 15° cephalad Patellofemoral compartment tendon rupture
(patellar articular facets)
Tunnel/ Prone; knee 45° flex; beam Posterior femoral condyles, inter- Patellofemoral arthritis, mal-
notch is caudal at knee joint condylar notch, tibial eminence alignment or patellar tilt

Merchant Supine; legs of table at 45°; Patellofemoral compartment Osteochondral fx/defect, femo-
Rosenberg beam at PF joint (patellar articular facets) ral condyle or tibial eminence
Medial/lateral compartments fx, DJD/osteoarthritis
PA (weight-bearing); knees
at 45° Articular surface lesions, DJD,
tilt or malalignment

Osteoarthritis of WB portion of
posterior condyles

290 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

AP radiograph RADIOLOGY • Leg/Knee 9
Lateral radiograph
Alignment radiograph

Tibial Diaphysis Center
plateau of hip
Metaphysis Tibial
plafond
Fibula
Medial Center
Lateral malleolus of knee
malleolus
Fibula Center
Tibial of ankle (a
plateau Tibial line drawn
Tibial plafond from the hip
tubercle to the ankle
should pass
Diaphysis the center
of the knee
in neutral
alignment)

RADIOGRAPH TECHNIQUE FINDINGS CLINICAL APPLICATION

LEG Fractures, deformity, infection, etc
Fractures, deformity, infection, etc
AP tibia Supine; beam at mid Tibia and surrounding soft tissues
tibia Determine malalignment/deformity
Used for leg length discrepancy
Lateral tibia Supine; beam later- Tibia and surrounding soft tissues Intraarticular condyle, plateau,
ally mid-tibia pilon fxs
Ligament ruptures, meniscal tears,
See Foot & Ankle chapter to see views of the ankle. OCD, stress fxs, tumor, infection
Stress fxs, infection, tumor
OTHER STUDIES

Alignment films Bilateral full length Full lower extremity alignment
hip to ankle, WB

Scanogram Entire bilateral LE Measure length of bones
with ruler

CT Axial, coronal, & Articular congruity, fracture

sagittal views fragments

MRI Sequence protocols Soft tissues: ligaments, meniscus,
vary articular cartilage, bone marrow

Bone scan Radioisotope All bones evaluated

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 291

9 Leg/Knee • TRAUMA

Fracture of Patella

Nondisplaced trans- Displaced transverse Transverse fracture Severely comminuted
verse fracture with fracture with tears with comminution of fracture
intact retinacula in retinacula distal pole

Dislocation of Knee Joint
Types of dislocation

Anterior Posterior Lateral Medial Rotational

DESCRIPTION EVALUATION CLASSIFICATION TREATMENT

PATELLAR FRACTURE

• Mechanism: direct & indi- Hx: Trauma, pain, cannot Descriptive/location: • Nondisplaced or
rect: e.g., fall, dashboard, extend knee, swelling comminuted—knee
etc. PE: “Dome” effusion, ten- ‫ ؠ‬Nondisplaced brace/cast 6-8 wk, ROM
derness, ϩ/Ϫ palpable ‫ ؠ‬Transverse
• Pull of quadriceps and ten- defect, inability to extend ‫ ؠ‬Vertical • Displaced (Ͼ2-3mm):
dons displace most fxs knee ‫ ؠ‬Stellate ORIF (e.g., tension
XR: Knee trauma series ‫ ؠ‬Inferior/superior pole bands) to restore articu-
• If intact, retinaculum resists CT: Not usually needed, will ‫ ؠ‬Comminuted lar surface
displacement of fragments show fx fragments
• Severely comminuted:
• Do not confuse with bipar- may require full or par-
tite patella (unfused supero- tial patellectomy
lateral corner)

COMPLICATIONS: Osteoarthritis and/or pain, decreased motion and/or strength, osteonecrosis, refracture

KNEE DISLOCATION

• Rare: ortho. emergency Hx: Trauma, pain, inability By position: • Early reduction essen-
• Usually high-energy injury to bear weight ‫ ؠ‬Anterior tial; postreduction neu-
• Multiple ligaments & other PE: Large effusion, soft tis- ‫ ؠ‬Posterior rologic exam and x-rays
sue swelling, deformity, ‫ ؠ‬Lateral
soft tissue are disrupted pain, ϩ/Ϫ distal pulses/ ‫ ؠ‬Medial • Immobilize (cast) 6-8wk
• High incidence of associ- peroneal nerve function ‫ ؠ‬Rotatory: anterome- (if ligaments not torn)
XR: AP/lateral
ated fx & neurovascular AGRAM: Evaluate for arte- dial or anterolateral • Surgery if irreducible or
injury rial injury vascular injury (revascu-
• Many spontaneously MR: Ligament injury, me- larize within 6 hr ϩ
reduce; must keep index of niscus, articular cartilage fasciotomy).
suspicion for injury injury
• Close follow-up is important • Early vs. delayed
for good result ligament repair/
reconstruction

COMPLICATIONS: Neurovascular: popliteal artery, peroneal nerve injury, knee stiffness (#1), chronic instability

292 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

TRAUMA • Leg/Knee 9

Tibial Plateau Fracture

I. Split fracture of lateral tibial plateau II. Split fracture of lateral condyle III. Depression of lateral tibial
plus depression of tibial plateau plateau without split fracture

IV. Comminuted split fracture of medial V. Biocondylar fracture involving VI. Fracture of lateral tibial plateau
tibial plateau and tibial spine both tibial plateaus with widening with separation of metaphyseal-
diaphyseal junction

DESCRIPTION EVALUATION CLASSIFICATION TREATMENT

TIBIAL PLATEAU FRACTURE

• Mechanism: axial load AND Hx: Trauma, pain, swell- Schatzker (6 types): • Consider joint aspiration
varus/valgus stress ing, inability to bear I: Lateral plateau split fx • Nondisplaced (Ͻ3mm
weight II: Lat. split/depression fx
• Restoration of articular PE: Effusion, tenderness; III: Lat. plateau depression step off,Ͻ5mm gap-
surface/congruity is important do thorough neurovas- IV: Medial plat. split fx ping): knee brace/cast
cular exam. V: Bicondylar plateau fx 6-8wk, NWB 6-12wk
• Metaphyseal injury: bone will XR: Knee trauma series VI: Fx w/metaphyseal- • Displaced: ORIF ϩ/Ϫ
compress, leading to func- CT: To better define fx bone graft (plates &
tional bone loss; may need lines & comminution. diaphyseal separation screws). Early ROM but
bone graft Needed for preop plan- Types IV-VI usually result NWB 12wk
ning. from high-energy • Avoid both medial &
• Lateral fracture more com- AGRAM: If decreased trauma lateral periosteal strip-
mon than medial pulses. Consider in all ping (incr. nonunion
type IV fxs rate)
• Associated meniscal (50%) • Repair torn ligaments/
and ligament (MCLϾACL) menisci
tears

COMPLICATIONS: compartment syndrome, posttraumatic osteoarthritis, persistent knee pain, popliteal artery injury

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9 Leg/Knee • TRAUMA

Fracture of Shaft of Tibia

Transverse Spiral Comminuted Segmental
fracture; fracture fracture with fracture
fibula with marked with
intact shortening shortening marked
shortening

Incisions for Compartment Syndome of Leg

Interosseous membrane Anterior compartment
Extensor muscles
Deep posterior compartment Tibia tibialis anterior
extensor digitorum longus
Deep flexor muscles extensor hallucis longus
flexor digitorum longus Anterior tibial a. and v.
tibialis anterior Deep peroneal n.
flexor hallucis longus
Anterolateral incision
Posterior tibial a. and n.
Tibial n. Anterior intermuscular septum
Peroneal a. and n.

Posteromedial incision Fibula Lateral compartment
Peroneal muscles
Transverse intermuscular septum Crural (encircling) fascia peroneus longus
peroneus brevis
Superficial posterior compartment Superficial peroneal n.
Superficial flexor muscles
soleus Posterior intermuscular septum
gastrocnemius
plantaris tendon

DESCRIPTION EVALUATION CLASSIFICATION TREATMENT

TIBIA SHAFT FRACTURE

• Common long bone fx Hx: Trauma, pain, swelling, Descriptive: • Nondisplaced: long leg
• Usually high-E trauma inability to bear weight Location cast 8wk (best for pedi-
• Condition of surrounding PE: Swelling, deformity, Displaced/comminuted atrics, seldom used in
ϩ/Ϫ firm/tense compart- Type: transverse, spiral adults)
soft tissues is critically ments oblique
important to success of XR: AP & lateral of tib./fib. Rotation/angulation • Displaced/unstable:
outcome (also knee & ankle series) reamed, locked IM nail
• Compartment syndrome: CT: Not usually needed
consider in ALL fxs AGRAM: If decreased • Open fractures: thorough
• Subcutaneous position of pulses I&D is critical. External
tibia predisposes it to fixation is useful for
open fractures these fractures.
• May lead to amputation
• Fasciotomies for com-
partment syndrome

COMPLICATIONS: compartment syndrome, nonunion & malunion, knee pain (from IM nail), ankle and/or knee stiffness

COMPARTMENT SYNDROME

• Incr. pressure in closed Hx: Trauma, pain XR: Evaluate for fractures • Usually a clinical diagnosis
space/compartment PE: 5 P’s: pain (w/passive Angiogram: If needed to • Emergent fasciotomy
stretch), paresthesia, pal- evaluate for vascular inj.
• Compartments (4): have lor, pulseless, paralysis Compartment Pressures: (usually two incisions)
rigid fibroosseous borders Firm/tense compartments 1. Absolute: Ͼ30-40mmHg
2. ⌬P: Ͻ30mmHg of
• Mechanism: trauma
(fracture, crush) vascular diastolic blood pressure
injury, burn

294 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

TRAUMA • Leg/Knee 9

Torn deltoid
ligament

Pilon fracture
Usual cause is vertical loading of ankle joint,
eg, falling from height and landing on heel
(usually with ankle dorsiflexed). Fracture and
compression of articular surface of tibia plus
separation of malleoli and fracture of fibula

Maisonneuve fracture
Complete disruption of tibiofibular syndesmosis with
diastasis caused by external rotation of talus and trans-
mission of force to proximal fibula, resulting in high
fracture of fibula. Interosseous membrane torn
longitudinally. Radiograph shows repair with long
transverse screw (these fractures easily missed on
radiographs)

DESCRIPTION EVALUATION CLASSIFICATION TREATMENT

MAISONNEUVE FRACTURE

• Complete syndesmosis Hx: Trauma, ankle pain,ϩ/Ϫ knee Descriptive: Reduce and stabilize
disruption with diastasis pain Location syndesmosis (e.g.,
& proximal fibula fx PE: Ankle pain, swelling, proxi- Type: Spiral with a screw); immobi-
mal fibula tenderness lize while healing
• Variant of ankle fracture XR: Leg and ankle series. May Oblique
& deltoid ligament need stress views of ankle to Comminuted
rupture see instability

• Unstable fracture

COMPLICATIONS: ankle instability, ankle arthritis

PILON (DISTAL TIBIA) FRACTURE

• Intraarticular: through Hx: Trauma, cannot bear weight, Ruedi/Allgower • Nondisplaced: cast &
distal articular/WB pain, swelling (3 types): NWB for 6-12wk
surface PE: Effusion, tenderness; do I: Non or minimally
good neurovascular exam displaced • Displaced/comminuted:
• Soft tissue swelling leads XR: AP/lateral (obliques) II: Displaced: articular early external fixation
to complications with CT: Needed to better define fx surface incongruous and delayed (14 days)
early open treatment and preop plan III: Comminuted articular ORIF; (plates & screws
surface ϩ/Ϫ bone grafting)
• Restoration of articular
surface congruity is es-
sential

• Healing is often slow

COMPLICATIONS: posttraumatic DJD, (almost 100% in comminuted fxs), stiffness, malunion, wound complications

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9 Leg/Knee • JOINTS

Anterior view Femur
of knee

Trochlea

Patella

Lateral Lateral Medial
condyle epicondyle epicondyle

Lateral Medial Lateral Medial
plateau condyle condyle condyle
of femur of femur
Gerdy Medial
tubercle plateau Lateral Medial
condyle condyle
of tibia of tibia

Line of attachment of synovium Head of Tibia
(edge of articular cartilage) to fibula
distal femur
Line of reflection of synovial Fibula Intercondylar
membrane eminence

KNEE

Structure

• Comprises 3 separate articulations
‫ ؠ‬Medial & lateral femorotibial joints (2)—condyloid (hinge) joints. Femoral condyles articulate with corresponding tibial plateaus.
‫ ؠ‬Patellofemoral joint (1)—sellar (gliding) joint. Patella articulates with femoral trochlear groove.

• 3 compartments in the knee: medial, lateral, patellofemoral
• Capsule surrounds entire joint (all three articulations/compartments) and extends proximally into the suprapatellar pouch.

‫ ؠ‬The capsule has a synovial lining that also covers the cruciate ligaments (making them intraarticular but extrasynovial)
• Articular (hyaline) cartilage (type II collagen) covers the femoral condyles, tibial plateaus, trochlear groove, and patellar facets.
• Menisci are interposed in the medial & lateral femorotibial joints to: 1.protect the articular cartilage, 2. give support to the knee.
• Knee axis (line drawn between weight-bearing portion of medial & lateral femoral condyles) is parallel to the ground.

‫ ؠ‬Mechanical axis of the femur is 3° valgus to the vertical axis, allowing the larger MFC to align with the LFC parallel to the
ground.

‫ ؠ‬Mechanical axis of the tibia is 3° varus to the vertical axis (87° to knee axis).

Kinematics

• Inherently unstable joint. Bony morphology adds little stability. Stability primarily provided by surrounding static and dynamic stabi-
lizers. (Dynamic stabilizers may compensate when static stabilizers are injured [e.g., complete or partial ACL rupture].)
‫ ؠ‬Medial: Static—superficial and deep medial collateral ligaments (MCL), posterior oblique ligament (POL).
Dynamic—semimembranosus, vastus medialis, medial gastrocnemius, PES tendons
‫ ؠ‬Lateral: Static—lateral collateral ligament (LCL), iliotibial band (ITB), arcuate ligament.
Dynamic—popliteus, biceps femoris, lateral gastrocnemius

• Not a simple hinge joint. The knee has 6 degrees of motion:
‫ ؠ‬Extension/flexion, IR/ER, varus/valgus, anterior/posterior translation, medial/lateral translation, compression/distraction

• Flexion & extension are the primary motions in the knee.
‫ ؠ‬Flexion is a combination of both “rolling” and “sliding” of the femur on the tibia in varying ratios depending on the degree of
flexion.
‫ ؠ‬Rolling: equal translation of tibiofemoral contact point & joint axis. Rolling predominates in early flexion.
‫ ؠ‬Gliding: translation of tibiofemoral contact point without moving the joint axis. Increased gliding is needed for deep flexion.
‫ ؠ‬The cruciate ligaments control the roll/glide function. The PCL alone can maintain this function (e.g., PCL retaining TKA).
‫ ؠ‬Normal motion: Extension/flexion: Ϫ5 to 140°. 115° needed to get out of a chair; 130° needed for fast running.

• IR/ER: about 10° total through arc of motion. Tibia IRs in swing, and ERs in stance via “screw home mechanism.”
‫ ؠ‬Screw home mechanism: larger MFC ERs tibia in full extension, tightening cruciates and stabilizing the knee in stance.
‫ ؠ‬Popliteus IRs the tibia to “unlock” the knee, loosen the cruciates, which allows the knee to initiate flexion.

• Other motions: Medial/lateral translation: minimal in normal knees
‫ ؠ‬Anterior/posterior translation: dependent on tissue laxity, usually within 2mm of contralateral side in normal knees
‫ ؠ‬Varus/valgus: approximately 5mm of gapping laterally or medially when stressed in normal knees

296 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Joint opened, Femur Suprapatellar JOINTS • Leg/Knee 9
(synovial) bursa
knee slightly Articularis MRI
in flexion genus muscle Cruciate ligaments
(covered by synovial ACL
Synovial membrane membrane) Intercondylar notch
(cut edge)
Medial condyle Anterior cruciate ligament
Lateral condyle of femur of femur visualized between femoral
Infrapatellar condyles
Origin of popliteus synovial fold
tendon (covered by Posterolateral
synovial membrane) Medial meniscus

Subpopliteal recess Alar folds (cut)

Lateral meniscus Infrapatellar fat pads
(lined by synovial
Fibular collateral membrane)
ligament
Suprapatellar (synovial)
Head of fibula bursa (roof reflected)
Patella (articular surface
on posterior aspect) Vastus medialis
muscle (reflected
Vastus lateralis muscle inferiorly)
(reflected inferiorly)

Right knee in flexion: anterior view

Anterior cruciate Posterior
ligament cruciate ligament

Lateral condyle of Medial condyle
femur (articular of femur (articular
surface) surface)

Popliteus tendon Medial meniscus

Fibular collateral Tibial collateral
ligament ligament

Lateral meniscus Medial condyle
of tibia
Transverse
ligament of knee

Head of fibula Tibial tuberosity
Gerdy’s tubercle

LIGAMENTS ATTACHMENTS FUNCTION/COMMENT

KNEE

Femorotibial Joint—Anterior Structures

Anterior cruciate ligament Posteromedial aspect of lateral Primary restraint to anterior tibial translation;
(ACL) femoral condyle to anterior tib- secondary restraint to varus (in extension) & IR
Anteromedial bundle ial eminence Tight in knee flexion, lax in extension
Posterolateral bundle Tight in knee extension, lax in flexion

Transverse meniscal ligament Connects both anterior horns of Stabilizes menisci; can be torn/injured
menisci to tibia

Other Structures

Ligamentum mucosum Distal femoral articulation to Synovial remnant. Covers anterior notch (ACL);
(anterior plica) anterior tibial plateau may need to be debrided for full visualization

Infrapatellar fat pad Posterior to patellar tendon, an- Cushions patellar tendon. Can become fibrotic
terior to intercondylar notch or impinged on, causing knee pain (Hoffa
syndrome)

See Patellofemoral Joint for other anterior structures

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 297

9 Leg/Knee • JOINTS Femur (popliteal surface) MRI
Attachment of joint capsule PCL
Right knee: posterior view
Adductor magnus tendon Plantaris muscle
Lateral head of
Medial head of gastrocnemius muscle and
gastrocnemius subtendinous bursa
muscle and
subtendinous bursa Lateral (fibular) collateral
Medial (tibial) ligament and its inferior
collateral ligament subtendinous bursa

Semi- Biceps femoris tendon
membranosus and bursa beneath it
tendon Popliteofibular ligament
Semimembranosus Arcuate ligament
bursa deep to (lateral arm)
tendon (broken line)
Oblique popliteal ligament Head of fibula
(tendinous expansion of semi- Posterior ligament of
membranosus muscle) fibular head
Attachment of joint capsule
Popliteus muscle
Tibia Interosseous membrane

Right knee in extension: Posteromedial compartment
posterior view
Posterior cruciate ligament
Adductor tubercle on
medial epicondyle of femur Anterior cruciate ligament

Medial condyle of Posterior meniscofemoral
femur (articular surface) ligament (of Wrisberg)

Medial meniscus Lateral condyle of Posterior
femur (articular cruciate
Tibial collateral ligament surface) ligament seen
beyond medial
Medial condyle of tibia Popliteus tendon meniscus

Fibular collateral
ligament

Lateral meniscus Broken lines
Head of fibula indicate medial
collateral
ligament

LIGAMENTS ATTACHMENTS COMMENTS

Posterior cruciate KNEE
ligament (PCL)
Femorotibial Joint—Posterior Structures
Anterolateral bundle
Posteromedial bundle Lateral aspect (in notch) of medial Primary restraint to posterior tibial translation
Meniscofemoral ligaments femoral condyle to post. proximal Secondary restraint to varus, valgus, and ER
tibia (below joint line)
Ligament of Humphrey Ant. origin on condyle, lat. on tibia Tight in knee flexion, lax in extension
Ligament of Wrisberg Post. origin on condyle, med. on tibia Tight in knee extension, lax in flexion
Oblique popliteal
ligament (OPL) Posterior lateral meniscus to MFC Variably present. Rarely are both present
and/or PCL, either:
Anterior to PCL Contributes to PCL function & stabilizes meniscus
Posterior to PCL Contributes to PCL function & stabilizes meniscus

Origin on semimembranosus inser- Tightens posterior capsule when semimembrano-
tion on posterior tibia; inserts on sus contracts; considered part of “posterome-
posterior LFC & capsule dial” corner

298 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

JOINTS • Leg/Knee 9

Biceps Knee joint: lateral view Vastus lateralis Posterolateral Iliotibial band (cut)
femoris muscle oblique view Plantaris muscle
muscle Short (cut)
head lliotibial Biceps Gastrocnemius muscle
Long (lateral head cut)
head tract femoris (cut)
band Lateral joint capsule
Peroneal
Lateral retinaculum
Bursa deep to nerve (cut)
iliotibial tract Lateral patello-
Quadriceps Gastrocnemius muscle femoral ligament
Lateral (fibular) femoris
collateral ligament (medial head cut) Popliteus tendon
and bursa deep to it tendon (insertion)
Posterior joint
Plantaris muscle Lateral Lateral collateral
capsule ligament
Biceps femoris patellar
tendon and its retinaculum Oblique Fabellofibular
inferior sub- popliteal ligament
tendinous bursa
Patella ligament Popliteofibular
Common fibular ligament
(peroneal) nerve Lateral patellar Semi-
tibial ligament membranous Iliotibial band (cut)
Gastrocnemius tendon (cut)
muscle Joint capsule Lateral arm
of knee Medial arm arcuate ligament
Head of fibula arcuate
Patellar ligament Biceps femoris (cut)
ligament
Inferior lateral Deep peroneal nerve
Tibial geniculate artery
tuberosity

Popliteus muscle

Soleus Fibularis (peroneus) Tibialis anterior Tibia Superficial
muscle muscle Peroneal nerve (cut) Fibula peroneal nerve
longus muscle

LIGAMENTS ATTACHMENTS FUNCTION/COMMENT

KNEE

Iliotibial band (tract) (ITB) Femorotibial Joint—Lateral and Posterolateral Structures

First Layer—Superficial

3 insertions: 1.Gerdy’s tubercle, 2. patella and Stabilizes lateral knee—“accessory anterolateral liga-
patellar tendon, 3. supracondylar tubercle ment.” Post. in flexion (ERs tibia), ant. in extension

Biceps femoris 2 heads insert on fibular head, lateral to LCL Lateral stabilizer, also externally rotates tibia

Lateral patellofemoral ligament Second Layer—Middle
Lateral patellar retinaculum
Lateral femur to lateral edge of patella May need release if tightened and causing patella tilt
SUPERFICIAL LAMINA Vastus fascia to tibia & patella and abnormal lateral articular cartilage wear

Third Layer—Deep

Lateral collateral lig. (LCL) Lateral epicondyle to medial fibular head Primary restraint to varus stress, also resists ER

Fabellofibular ligament Fibula head to fabella, usually with arcuate lig. Variably present, also called “short collateral”

DEEP LAMINA

Popliteus muscle and tendon Inserts anterior and distal to LCL origin Resists tibia ER, varus, and posterior translation

Popliteofibular ligament (PFL) Popliteus musculotendinous jxn to fibula head Primary static restraint to external rotation (ER)

Capsule Femur to tibia. Extends 15mm below joint line Reinforced by other structures; resists varus & ER

Arcuate ligament Lateral arm: fibular head to posterior femur Variably present, Y-shaped: two arms. Lateral arm
Lateral meniscus Medial arm: post-lat femur, blends with OPL covers popliteus supporting posterolateral knee

Other Gives concavity to the convex lateral plateau

To lateral plateau via coronary ligaments

Lateral head of gastrocnemius Origin is on posterior lateral condyle Adds dynamic support to posterolateral knee

• The inferior lateral geniculate artery passes between the superficial and deep lamina of the third layer of the posterolateral corner.
• The LCL, popliteus, and popliteofibular ligament are the most consistent structures and are the focus of surgical reconstruction.
• Most of the posterolateral structures act as stabilizers to varus & ER forces. They also are secondary stabilizers to posterior translation.
• Arcuate “complex” refers to posterolateral stabilizing structures including: LCL, arcuate ligament, popliteus, & lateral gastrocnemius.

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9 Leg/Knee • JOINTS

Vastus Sartorius muscle Quadriceps Tendon of
medialis femoris (vastus adductor magnus
muscle Gracilis muscle medialis
Quadriceps Tendon of muscle) Gastrocnemius muscle
femoris tendon semitendinosus muscle (medial head)

Medial Adductor magnus tendon Med. sup. Semimembranosus
epicondyle genic. a. tendon
of femur Semimembranosus
Medial muscle and tendon Quadratus Bursa
patellofemoral Posterior tendon
ligament joint capsule Medial
Patella meniscus
Patella Medial (tibial) Tendons of:
collateral ligament Medial expansion Sartorius muscle
Medial patellar (retinaculum) of Gracilis muscle
retinaculum Posterior tendon Semitendinosus
oblique ligament muscle
Medial Tibia
patellotibial Semimembranosus Medial
ligament
bursa collateral
Joint capsule
Anserine bursa ligament
Patellar ligament
deep to Pes Patellar
Tibial tuberosity Semitendinosus, anserinus tendon
Gracilis and

Sartorius tendons Tubercle

Gastrocnemius muscle of tibia

Soleus muscle

Knee joint: medial view Ligaments of the knee: medial view

LIGAMENTS ATTACHMENTS FUNCTION/COMMENT

KNEE

Sartorius Femorotibial Joint—Medial Structures
First Layer—Superficial

Becomes fascial layer at insertion at Pes Covers other tendons at Pes insertion

Fascia Deep fascia from thigh continues to knee Blends with retinaculum (ant.) & capsule
(post.)
Superficial medial
collateral (MCL) Second Layer—Middle

Medial epicondyle to tibia (deep to Pes) Primary restraint to valgus force (esp. at 30°)
Broad insertion is 5-7cm below joint line Secondary stabilizer to anterior translation & IR

Posterior oblique Adductor tubercle (post. to MCL) to poste- Static stabilizer against valgus. Lax in flexion
ligament (POL) rior tibia, PH of med. meniscus, & cap- but tightens dynamically due to semimembr.
sule

Medial patellofemoral Medial patella to medial femoral epicondyle Primary static stabilizer against patella lateraliza-
ligament (MPFL) tion; may need repair/reconstruction after dx

Medial patellar Continuous w/vastus fascia to tibia & patella Can also be injured in lateral patellar subluxation
retinaculum

Semimembranosus Inserts posteromedial on tibia Gives posteromedial support

Deep medial Third Layer—Deep Stabilizes meniscus. Also known as medial
collateral (MCL) capsular ligament or middle 1⁄3 capsular
Meniscofemoral fibers Inserts on medial meniscus & tibia plateau ligament
Meniscotibial fibers 2 sets of fibers:

Femur to meniscus
Tibia to meniscus

Capsule Femur to tibia, extends 15mm below joint Reinforced by other posteromedial structures
Medial meniscus
Other Posterior horn is secondary stabilizer to ante-
rior translation. Becomes 1° in ACL
Attached firmly to medial tibial plateau via
coronary ligaments

Medial head of gastroc- Origin on the posteromedial femur Provides some minor additional dynamic
nemius support

• Gracilis and semitendinosus tendons are between layers 1 and 2 and act as secondary dynamic medial stabilizers.
• The POL is a confluence of layers 2 and 3 tissues that are indistinct in the posteromedial aspect of the knee.

300 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

JOINTS • Leg/Knee 9

Lateral MRI

Quadriceps
tendon

Sagittal section Patella Articular
(lateral to midline of knee) cartilage
Subchondral Posterior
Femur bone (of horn of
Articularis genus muscle femur) lateral
mensicus
Quadriceps Fibula
femoris tendon
Iliotibial
Suprapatellar fat body band
(ITB)
Suprapatellar Patellar ACL
(synovial) bursa tendon Lateral
meniscus
Articular cavity

Patella Lateral Anterior horn of Tibial plateau
subtendinous lateral mensicus
Subcutaneous bursa of
prepatellar gastrocnemius Coronal MRI
bursa muscle

Synovial Synovial
membrane membrane

Patellar Articular PCL
ligament cartilages
Tibia Superficial
Infrapatellar MCL
fat pad Tibial tuberosity Deep MCL

Subcutaneous
infrapatellar
bursa

Deep
(subtendinous)
infrapatellar
bursa

Lateral
meniscus

Posterior cruciate Medial
ligament (PCL) meniscus

Deep medial Anterior cruciate
collateral ligament (ACL)
ligament Popliteus tendon
(MCL)
Lateral collateral
Medial ligament (LCL)
meniscus
Lateral meniscus
Superficial
medial collateral Ligaments of knee:
ligament (MCL) coronal (frontal) section

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 301

9 Leg/Knee • JOINTS Lateral compartment

Medial compartment

Medial meniscus visualized below Collagen fibers Lateral meniscus visualized.
femoral condyle. Meniscus rises (finely woven) Varus stress raises meniscus
with valgus stress, permitting from tibial condyle
inspection beneath it
Red-red zone Vascular zones
Collagen fibers Red-white zone of meniscus
(random orientation) White-white zone

Circumferential
collagen fibers

Radial
collagen fibers

MENISCUS

Structure

• Fibrocartilage discs interposed in femorotibial joints between femoral condyles and tibial plateaus. Have a triangular
cross section—thickest at the periphery, then tapering to a thin central edge.

• Histologically made up of collagen (mostly type 1, also 2, 3, 5, 6), cells (fibrochondrocytes), water, proteoglycans,
glycoproteins, elastin

• 3 layers seen microscopically:
1. Superficial layer: woven collagen fiber pattern
2. Surface layer: randomly oriented collagen fiber pattern
3. Middle (deepest) layer: circumferential (longitudinal) oriented fibers. These fibers dissipate hoop stresses.
Radial fibers. These fibers acts as “ties” to hold the circumferential fibers.

• Vascular supply from superior and inferior medial and lateral geniculate arteries. They form perimeniscal plexus in
synovium/capsule. Peripheral portion (10-30% medially, 10-25% laterally) is vascular via vessels from the perimenis-
cal plexus. 3 zones:
‫ ؠ‬Red zone: 3mm from capsular junction (most tears will heal)
‫ ؠ‬Red/white zone: 3-5mm from capsular junction (some tears will heal)
‫ ؠ‬White zone: Ͼ5mm from capsular junction (most tears will not heal)
The central, avascular 2⁄3 of the menisci receive nutrition from the synovial fluid

• Medial meniscus: C-shaped, less mobile, firmly attached to tibia (via coronary ligaments) and capsule (via deep MCL)
at midbody

• Lateral meniscus: “circular”, more mobile, loose peripheral attachments, no attachment at popliteal hiatus (where pop-
liteus tendon enters joint)

Function

1. Load transmission and shock absorption: the menisci absorb 50% (in extension) or 85% (in flexion) of forces
across femorotibial joint. The transmission of this load to the meniscus helps protect the articular cartilage

2. Joint congruity and stability: the menisci create congruity between the curved condyles and flat plateaus, which
increases stability. The menisci (esp. PHMM) also act as secondary stabilizers to translation (esp. in the ligament-
deficient knee)

3. Joint lubrication: the menisci help distribute synovial fluid across the articular surfaces.
4. Joint nutrition: the menisci absorb, then release synovial fluid nutrients for the cartilage.
5. Proprioception: nerve endings provide sensory feedback for joint position.

302 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Patellar ligament Inferior view JOINTS • Leg/Knee 9
Medial patellar retinaculum
blended into joint capsule Posterior aspect lliotibial tract blended into lateral
Suprapatellar synovial bursa MRI patellar retinaculum and capsule
Synovial membrane (cut edge)
Infrapatellar synovial fold Bursa
Posterior cruciate ligament Subpopliteal recess
Medial (tibial) collateral ligament Popliteus tendon
(superficial and deep parts) Lateral (fibular)
Medial condyle of femur collateral ligament
Oblique popliteal ligament Bursa
Semimembranosus tendon Lateral condyle of femur
Anterior cruciate ligament
Patellar tendon Arcuate popliteal ligament

Retinaculum Lateral femoral condyle
Popliteal artery
Medial femoral condyle

Patellar ligament Superior view Infrapatellar fat pad
Anterior cruciate ligament lliotibial tract
Anterior aspect blended into capsule
Joint capsule MRI Superior articular surface
Superior articular surface of tibial plateau (lateral facet)
of tibial plateau (medial facet) Lateral meniscus
Subpopliteal recess
Synovial membrane Popliteus tendon
Medial meniscus Bursa
Fibular collateral ligament
Medial collateral ligament Arcuate popliteal ligament
(deep part bound to
medial meniscus) Posterior meniscofemoral ligament
Posterior cruciate ligament
Oblique popliteal ligament Patellar tendon

Semimembranosus tendon Lateral meniscus

Medial meniscus LCL

PCL Popliteus tendon
Popliteal artery

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 303

9 Leg/Knee • JOINTS

Vastus intermedius muscle Right knee in extension Suprapatellar pouch

Vastus lateralis muscle Femur
Articularis genus muscle
lliotibial tract
Vastus medialis muscle
Lateral patellar
retinaculum Rectus femoris tendon
(becoming quadriceps
Lateral epicondyle femoris tendon)
of femur
Lateral (fibular) collateral Patella Arthroscopic view
ligament and bursa Medial epicondyle of femur shows patella above,
trochlear groove of
Biceps femoris tendon and its Medial patellar retinaculum femur below,
inferior subtendinous bursa suprapatellar pouch
Medial (tibial) in between
Broken line indicates collateral ligament
bursa deep to iliotibial tract
Semitendinosus, Pes
Insertion of iliotibial tract Gracilis and anserinus
to Gerdy’s tubercle and Sartorius tendons
oblique line of tibia
Anserine bursa
Common fibular
(peroneal) nerve

Head of fibula Medial condyle of tibia

Fibularis (peroneus) Tibial tuberosity Patellar ligament Anteromedial
longus muscle Gastrocnemius muscle compartment

Extensor digitorum longus muscle

Tibialis anterior muscle

LIGAMENTS ATTACHMENTS FUNCTION/COMMENT

KNEE

Patellofemoral Joint

Function

• Composed of quadriceps tendon, patella, patellar tendon (ligament), and additional patella-stabilizing ligaments.
• Extensor mechanism (of the knee) is primary role of this joint. The patella increases the moment arm from joint axis,

increasing the mechanical advantage and quadriceps pull in extension.
• Stability of the patella in the trochlear groove results from both bony morphology and static and dynamic stabilizers.

Hypoplastic LFC or patellar ridge, a flat trochlea, or increased “Q” angle can all predispose the patella to dislocation.
• The patella begins to engage the trochlea at 20° of flexion and is fully engaged by 40°. The articulation point moves

proximally with increased flexion. The odd facet (far medial) of the patella articulates in full flexion.
• Joint reaction forces can be very high in this joint: 3ϫ body weight with stairs, 7ϫ body weight with deep bending.

The articular cartilage is up to 5mm (thickest in the body) to accommodate for these high forces.

Structure

Quadriceps tendon Quadriceps to superior pole of patella Can rupture with eccentric
contraction (usu. Ͼ40y.o.)

Patellar tendon (ligament) Inferior pole of patella to tibial Can rupture with eccentric
tuberosity contraction (usu. Ͼ40y.o.)

Patellofemoral ligaments Femoral epicondyles to medial/lateral Primary stabilizers of patella
Medial (MPFL), lateral (LPFL)
patella (esp. MPFL)

Patellotibial ligaments (med. & lat.) Tibial plateaus to medial/lateral patella Minor patellar stabilizer

Patellomeniscal ligaments (med. & lat.) Patella to periphery of menisci Secondary stabilizers of patella

Patellar retinaculum (med. & lat.) Inserts on both the femur and tibia Minor patellar stabilizer

Other

• Patella position can evaluated on lateral radiograph (30° flexion) with Insall ratio (patella [diagonal] length/patellar
tendon length). Normal ratio is 1.0 (0.8 to 1.2). Ͼ1.2 indicates patella baja, Ͻ0.8 indicates patella alta.

• Dynamic stabilizers: quadriceps, adductor magnus, ITB, and vastus medialis and lateralis
• Medial patellofemoral ligament (MPFL): primary restraint to lateral dislocation (most common)

304 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

JOINTS • Leg/Knee 9

Patellofemoral Joint MRI
Patella
Lateral retinaculum Medial Medial patellar facet Lateral patellar facet
retinaculum Medial retinaculum
Lateral retinaculum
Trochlea
Articular cartilage
Normally, patella rides in groove between Femoral trochlea (groove)
medial and lateral femoral condyles

Anterior view with ligament attachments

Superior view Iliotibial tract Posterior Cruciate
Anterior ligaments
Posterior ligament Posterior Lateral (fibular)
of fibular head intercondylar area collateral ligament Medial
(origin of posterior (tibial)
Apex cruciate ligament) collateral
ligament
Head Posterior Intercondylar Biceps femoris
Fibula eminence tendon Patellar
ligament
Anterior Tibia Head of fibula
ligament Medial Tibial
of fibular condyle Anterior ligament tuberosity
head Superior of fibular head
articular surface Anterior
Lateral (medial facet) Gerdy’s tubercle border
condyle Interosseous
border
Superior Anterior Medial Intercondylar Anterior border Interosseous
articular surface Lateral tubercles Interosseous border membrane
(lateral facet)
Tibial tuberosity Lateral surface Lateral
Anterior surface
intercondylar area
(origin of anterior Tibia
cruciate ligament)

Fibula

Cross section

Interosseous border Lateral surface

Interosseous membrane Anterior border Anterior Medial
Interosseous border Medial surface tibiofibular malleolus
Tibia ligament
Anterior border Medial border Medial (deltoid)
Lateral surface Posterior surface Lateral malleolus ligament of
ankle
Fibula Medial surface Calcaneofibular
ligament
Posterior border Medial crest Anterior
Posterior surface talofibular
ligament

LIGAMENTS ATTACHMENTS FUNCTION/COMMENT

PROXIMAL TIBIOFIBULAR JOINT

Anterior tibiofibular ligament Fibular head to anterior lateral tibia Broader and stronger than posterior ligament

Posterior tibiofibular ligament Fibular head to posterior lateral tibia Weaker than anterior ligament

Other

Interosseous membrane Lateral tibia to medial fibula Stout fibrous membrane separates anterior
& posterior compartments. Is disrupted in
Maisonneuve fracture

• This joint has minimal motion. Dislocation or disruption of this joint indicates high-energy trauma to the knee region.
• For distal tibiofibular joint, please see Chapter 10, Foot/Ankle.

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 305

9 Leg/Knee • MINOR PROCEDURES

Technique for injection of knee joint
Quadriceps tendon
Patella

Intercondylar Tibia Femur
notch Fibula
Injection sites

Patella tendon

Meniscus

Anterior view: points of
needle insertion indicated

Lateral view: needle in place

Knee arthrocentesis

STEPS

INJECTION

1. Ask patient about allergies.
2. Place patient in seated position with knee flexed and hanging.
3. Prep skin (iodine/soap) over the anterior knee.
4. Prepare syringe with local/steroid mixture on 21/22 gauge needle.
5. Palpate the “soft spot” between the border of the patellar tendon, the tibial plateau, and the femoral condyle.
6. May locally anesthetize the skin over the “soft spot.”
7. Horizontally insert the needle into the “soft spot,” aiming approximately 30° to the midline toward the intercondylar

notch. If the needle hits the condyle, redirect it more centrally into the notch.
8. Gently aspirate to confirm that you are not in a vessel.
9. Inject solution into knee. The fluid should flow easily.
10. Withdraw needle and dress the injection site.

ASPIRATION/ARTHROCENTESIS

1. Ask patient about allergies.
2. Place patient supine with the knee fully extended.
3. Palpate the borders of the patella and femoral condyle.
4. Prep skin (iodine/antiseptic soap) over this area.
5. Insert needle, usually 21 or 18 gauge (for thick fluid), horizontally into suprapatellar pouch at level of superior

pole of the patella.
6. Aspirate fluid into syringe (may use multiple syringes if needed).
7. Gently compress knee to “milk” fluid to the pouch for aspiration.
8. Withdraw needle and dress the injection site.

306 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

HISTORY • Leg/Knee 9

PCL Injury Sprains ACL Injury
Usual causes include hyperextension injury, Usual cause is forceful impact on Usual cause is twisting of
as occurs from stepping into hole, and direct posterolateral aspect of knee with foot hyperextended knee, as in
blow to flexed knee anchored, producing valgus stress landing after basketball
on knee joint jump shot

QUESTION ANSWER CLINICAL APPLICATION
1. Age
2. Pain Young Trauma: ligamentous or meniscal injury, fracture
Middle aged, elderly Arthritis
a. Onset
b. Location Acute Trauma: fx, dislocation, soft tissue (ligament/meniscus) injury, septic
bursitis/arthritis
c. Occurrence Chronic Arthritis, infection, tendinitis/bursitis, overuse, tumor
3. Stiffness Anterior Quadriceps or patellar tear or tendinitis, prepatellar bursitis,
4. Swelling patellofemoral dysfunction
Posterior Meniscus tear (posterior horn), Baker’s cyst, PCL injury
5. Instability Lateral Meniscus tear (joint line), collateral lig. injury, arthritis, ITB syndrome
6. Trauma
Medial Meniscus tear (joint line), collateral ligament injury, arthritis, pes bursitis
7. Activity Night pain Tumor, infection
With activity Etiology of pain likely from joint
8. Neurologic sx
9. Systemic Without locking Arthritis, effusion (trauma, infection)
10. Hx of With locking/catching Loose body, meniscal tear (esp. bucket handle), arthritis, synovial plica

arthritides Intraarticular Infection, trauma (OCD, meniscal tear, ACL/PCL injury, fracture)
Extraarticular Collateral ligament injury, bursitis, contusion, sprain
Acute (post injury) Acute (hours): ACL injury; subacute (day): meniscus injury, OCD
Acute (without injury) Infection: prepatellar bursitis, septic joint

Giving away/collapse Cruciate or collateral ligament injury/extensor mechanism injury
Giving away & pain Patellar subluxation/dislocation, pathologic plica, OCD

Mechanism: valgus MCL injury (ϩ/Ϫ terrible triad: MCL, ACL, medial meniscus injuries)
Varus force LCL or posterolateral corner injury
Flexion/posterior PCL injury (e.g., dashboard injury)
Twisting Noncontact: ACL injury; Contact: multiple ligaments
Cruciate ligament injury (esp. ACL), osteochondral fx, meniscal tear
Popping noise Degenerative and overuse etiology
None
Cruciate (ACL #1) or collateral ligament
Agility/cutting sports Patellofemoral etiology
Running, cycling etc. Meniscus tear
Squatting Distance able to ambulate equates with severity of arthritic disease
Walking
Neurologic disease, trauma (consider L-spine etiology)
Numbness, tingling
Infection, septic joint, tumor
Fevers, chills
Rheumatoid arthritis, gout, etc
Multiple joints
involved

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 307

9 Leg/Knee • PHYSICAL EXAM

Quadriceps atrophy

Prepatellar bursitis
(housemaid’s knee)

Q

Line of
incision

Cellulitis and Q angle formed by intersection of
induration lines from anterior superior iliac spine
and from tibial tuberosity through mid-
Osgood-Schlatter Disease Incision and drainage point of patella. Large Q angle pre-
Clinical appearance. Prominence over tibial often necessary disposes to patellar subluxation.
tuberosity partly due to soft-tissue swelling
and partly to avulsed fragments

EXAM TECHNIQUE/FINDINGS CLINICAL APPLICATION/DDX

Gait Varus thrust INSPECTION
Anterior Patella tracking
Flexed knee gait Can indicate LCL or posterolateral corner injury/insufficiency
Maltracking can lead to patellofemoral symptoms
Knee alignment From tight Achilles tendon or hamstrings, can lead to patellofemoral symptoms

Genu valgum (knock Normal knee alignment is clinically neutral (6° valgus radiographically).
knee) Evaluate while weight-bearing. Variations can be developmental or post-
Genu varum (bow leg) traumatic.
Q angle Can predispose to lateral compartment DJD, patella instability/maltracking

Swelling Can predispose to medial compartment DJD, ligamentous incompetency
Angle from ASIS to mid-patella to tibial tubercle. Nl: male Յ10°, female
Posterior Enlarged tibial tubercle Յ15°; increased angle predisposes to patellar subluxation, patellofemoral
Lateral symptoms
Mass Prepatellar: prepatellar bursitis (inflammatory or septic); intraarticular effu-
Musculature
Knee alignment sion: arthritis, infection, trauma (hemarthrosis): intraarticular fracture,
Recurvatum meniscal tear, ligament rupture
May be result of Osgood-Schlatter disease (esp. in adolescents)
Patella position
High-riding patella Baker’s cyst
Low-riding patella
Evaluated while weight-bearing
Quadriceps Possible PCL injury
Vastus medialis Best evaluated radiographically with Insall ratio (see Joints, Patellofemoral)
Patella alta: can predispose to patella instability
Patella baja: usually posttraumatic or postsurgical (possible arthrofibrosis)

Atrophy can result from injury, postoperative, or neurologic conditions
VMO atrophy may contribute to patellofemoral symptoms

308 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Joint line PHYSICAL EXAM • Leg/Knee 9
tenderness
Iliotibial band
Area of diffuse pain
and tenderness

Bulge sign
Medial side of knee
compressed or stroked proximally to move
fluid away from medial compartment.

Swelling and
palpable sulcus
above patella

Lateral side is quickly Rupture of quadriceps femoris Assess for
compressed or stroked distally; tendon at superior margin of effusion
bulge appears medial to patella. patella

EXAM TECHNIQUE/FINDINGS CLINICAL APPLICATION/DDX
Bony structures
Soft tissues PALPATION

Patella Tenderness at distal pole: tendinitis (jumper’s knee)
Tibial tubercle Tenderness with Osgood-Schlatter disease

Quadriceps tendon Defect: tendon rupture; tenderness: tendinitis
Patellar tendon Defect: tendon rupture; tenderness (esp. at insertion):
tendinitis (jumper’s knee)
Compress suprapatellar pouch Ballotable patella (effusion): arthritis, trauma, infection
Prepatellar bursa Edematous/tender bursae indicate correlating bursitis
Pes anserine bursa Tenderness indicates bursitis
Retinaculum/plica Thickened, tender plica is pathologic
Medial joint line and MCL Tenderness: medial meniscus tear or MCL injury
Lateral joint line and LCL Tenderness: lateral meniscus tear or LCL injury
Iliotibial band/LFC (anterolateral knee) Pain or tightness is pathologic
Popliteal fossa Mass consistent with Baker’s cyst, popliteal aneurysm
Compartments of leg (anterior, poste- Firm or tense compartment: compartment syndrome
rior, lateral)

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 309

9 Leg/Knee • PHYSICAL EXAM

Acute Anterior Compartment Syndrome

5 Ps, often early manifestations Paresthesia
of compartment syndrome Paresis (foot drop)

Pain

Hyperextension Septic bursitis Pulseless Pallor

0˚ 0˚
Extension (Limited
extension)
(Normal extension)

Flexion 30˚

Limited range
of motion

Normal range of (Limited
motion of knee joint flexion) 90˚

135˚ to 145˚ 135˚ to 145˚
(Normal flexion)

EXAM TECHNIQUE/FINDINGS CLINICAL APPLICATION/DDX

Flexion/extension RANGE OF MOTION

Tibial IR & ER Supine: heel to buttocks, Normal: flex 0 to 125-135°, extend 0 to 5-15°
then straight Flexion contracture: common in OA/DJD
Femoral nerve/saphenous (L4) Extensor lag (final 20º difficult): weak quadriceps
Peroneal nerve (L5) Note patellar tracking, pain, Decreased extension with effusion
and crepitus Abnormal tracking leads to anterior knee pain
Lateral sural
Superficial branch Stabilize femur, rotate tibia Normal 10-15° IR/ER
Tibial nerve (S1)
Medial sural NEUROVASCULAR
Sural nerve
Sensory
Femoral nerve (L2-4)
Sciatic: Tibial (L4-S3) Medial leg Deficit indicates corresponding nerve/root lesion
Peroneal (L4-S3)
Tibial nerve (S1) Deficit indicates corresponding nerve/root lesion
Peroneal (deep) n. (L4)
Peroneal (superficial) n. (L5) Proximal lateral leg
Distal lateral leg
Reflex (L4)
Deficit indicates corresponding nerve/root lesion
Pulse
Proximal posterolateral leg

Distal posterolateral leg Deficit indicates corresponding nerve/root lesion

Motor

Knee extension Weakness = Quadriceps or nerve/root lesion

Knee flexion Weakness = Biceps (LH) or nerve/root lesion
Knee flexion Weakness = Biceps (SH) or nerve/root lesion

Foot plantarflexion Weakness = TP, FHL, FDL, or nerve/root lesion

Foot dorsiflexion Weakness = TA or nerve/root lesion
Hallux dorsiflexion Weakness = EHL or nerve/root lesion

Other

Patellar Hypoactive/absence indicates L4 radiculopathy
Hyperactive may indicate UMN/myelopathic condition

Popliteal Diminished pulse can result from trauma

310 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Apprehension (Fairbank) PHYSICAL EXAM • Leg/Knee 9
test As examiner displaces
patella laterally, patient Anterior drawer test
feels pain and forcefully Patient supine on table, hip flexed 45°, knee 90°. Examiner sits on patient’s
contracts quadriceps foot to stabilize it, places hands on each side of upper calf and firmly pulls
femoris muscle. tibia forward. Movement of 5 mm or more is
positive test. Result also compared with
that for normal limb, which is tested
first.

Lachman test
With patient’s knee bent 20˚–30˚, examiner’s hands grasp limb over
distal femur and proximal tibia. Tibia pulled forward with femur
stabilized. Movement of 5 mm or more than that in normal
limb indicates rupture of anterior cruciate ligament.

EXAM TECHNIQUE CLINICAL APPLICATION/DDX

Patella displacement SPECIAL TESTS

Patella apprehension Patellofemoral Joint
J sign
Patella compression/grind Translate patella medially & laterally Divide patella into 4 quadrants. Patella should
translate 2 quadrants in both directions. De-
Joint line tenderness creased mobility indicates a tight retinaculum.
McMurray
Apley’s compression Relax knee, push patella laterally Pain/apprehension of subluxation: patellar in-
Lachman stability or medial retinaculum/MPFL injury

Anterior drawer Actively extend knee from flexed po- Lateral displacement of patella in full exten-
Pivot shift sition sion: maltracking

Extend knee, fire quads, compress Pain: chondromalacia, OCD, PF arthritis/DJD
patella of patella

Meniscus

Palpate both joint lines Most sensitive exam for meniscal tear when
tender (see page 309)

Flex/varus/ER knee, then extend Pop or pain suggests medial, meniscal tear
Flex/valgus/IR knee, then extend Pop or pain suggests lateral, meniscal tear

Prone, knee 90°, compress & rotate Pain or pop indicates meniscal tear

Anterior Cruciate Ligament

Flex knee 20-30°, anterior force on Laxity indicates ACL injury. Most sensitive
tibia exam for ACL rupture. Grade 1: 0-5mm, 2: 6-
10mm, 3: Ͼ10mm; A: good, B: no endpoint

Flex knee 90°, anterior force on tibia Laxity/anterior translation: ACL injury

Supine, extend knee, IR, valgus force Clunk with knee flexion indicates ACL injury. (If
on proximal tibia, then flex knee ACL is deficient, the tibia starts subluxated
and reduces with flexion, causing the clunk.)

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 311

9 Leg/Knee • PHYSICAL EXAM

Pivot shift test for anterolateral knee instability
Patient supine and relaxed. Examiner lifts heel of
foot to flex hip 45˚ keeping knee fully extended;
grasps knee with other hand, placing thumb beneath
head of fibula. Examiner applies strong internal
rotation to tibia and fibula at both knee and ankle
while lifting proximal fibula. Knee permitted to
flex about 20˚; examiner then pushes medially with
proximal hand and pulls with distal hand to produce
a valgus force at knee

As internal rotation, valgus force, and forward displacement of
lateral tibial condyle maintained, knee passively flexed. If
anterior subluxation of tibia (anterolateral instability) present,
sudden visible, audible, and palpable reduction occurs at about
20˚–40˚ flexion. Test positive if anterior cruciate ligament
ruptured, especially if lateral capsular ligament also torn

Posterior
drawer test

Posterior sag sign

Leg drops backward Procedure same as for
anterior drawer test,
312 NETTER’S CONCISE ORTHOPAEDIC ANATOMY except that pressure
on tibia is backward
instead of forward

PHYSICAL EXAM • Leg/Knee 9

Varus and valgus tests
Patient supine on table, relaxed, leg over edge
of table, flexed about 30˚. With one hand fixing
thigh, examiner places other hand just above

ankle and applies valgus stress. Degree of mobility
compared with that of uninjured side, which is
tested first. For varus stress test, direction of
pressure reversed.

External rotation
at 30° and 90° (dial test).
Test may be performed
prone or supine (shown).

External rotation
recurvatum test

EXAM TECHNIQUE CLINICAL APPLICATION/DDX

Posterior drawer SPECIAL TESTS
Posterior sag
Quadriceps active Posterior Cruciate Ligament
Reverse pivot shift
Flex knee 90°, posterior force on tibia Posterior translation: PCL injury
Valgus stress
Varus stress Supine, hip 45°, knee 90°, view Posterior translation of tibia (by gravity) on femur
laterally indicates PCL injury
Prone ER at 30° &
90° (Dial) Supine, knee 90°, fire quadriceps Posteriorly subluxated tibia translates anteriorly if
ER recurvatum PCL is deficient
Slocum
Posterior lateral Supine, flex knee 45°, ER, valgus Clunk with knee extension indicates PCL injury. (If
drawer force on proximal tibia, then extend PCL is deficient, the tibia is subluxated posteriorly,
Posterior medial knee then reduces w/extension, causing the clunk.)
drawer
Collateral Ligaments

Lateral force to knee at 30°, then 0° Laxity at 30°—MCL injury; 0°—MCL and cruciate
ligament injury

Medial force to knee at 30°, then 0° Laxity at 30°— LCL injury; 0°—LCL and cruciate
ligament injury

Other

Prone, ER both knees at 90°, then Increased ER at 30°: posterolateral corner (PLC) in-
30° (can be done supine) jury; at 90° PLC & PCL injuries

Supine, legs straight, raise legs by Recurvatum, varus, and IR of knee indicates PLC
toes (ϩ/Ϫ PCL) injury

Knee 90°, IR tibia 30°, anterior force Displacement: anterior & lateral injury (ACL & PLC))
Knee 90°, ER tibia 30°, anterior force Displacement: anterior & medial inj. (ACL, MCL, POL)

Knee 90º, ER tibia 15°, posterior Laxity indicates posterolateral corner and/or PCL
force injury

Knee 90°, IR tibia 30°, posterior Laxity indicates PCL and medial ligament (MCL, POL)
force injury

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 313

9 Leg/Knee • ORIGINS AND INSERTIONS

Anterior view Posterior view Plantaris muscle
Gastrocnemius muscle
Iliotibial tract Gastrocnemius muscle (lateral head)
(medial head) Popliteus muscle
Biceps femoris
muscle Semimembranosus Tibialis posterior
muscle muscle
Fibularis
(peroneus) Sartorius muscle Pes anserinus Flexor hallucis
longus muscle Gracilis muscle longus muscle
Semitendinosus Popliteus
Extensor muscle muscle Fibularis (peroneus)
digitorum brevis muscle
longus muscle Quadriceps femoris Soleus Plantaris muscle
muscle via muscle Soleus and
Extensor hallucis patellar ligament gastrocnemius
longus muscle Tibialis anterior Flexor muscles via
muscle digitorum calcaneal (Achilles)
Fibularis longus muscle tendon
(peroneus) Origins
brevis muscle Insertions Fibularis
(peroneus)
Fibularis Note: Attachments longus muscle
(peroneus) of intrinsic muscles
tertius muscle of foot not shown Flexor
digitorum
Fibularis Tibialis longus muscle
(peroneus) posterior muscle
brevis muscle
Tibialis
Fibularis anterior muscle
(peroneus)
tertius muscle

Extensor digitorum Flexor hallucis
longus muscle longus muscle

Extensor
hallucis
longus muscle

LATERAL FEMORAL MEDIAL FEMORAL FIBULAR HEAD PROXIMAL TIBIA
CONDYLE CONDYLE
Tibialis anterior (Gerdy’s tub.)
Lateral gastrocnemius ORIGINS Extensor digitorum longus
Plantaris
Popliteus (ant. & inf. to LCL) Medial gastrocnemius Soleus Quadriceps (tibial tubercle)
Ligaments: Iliotibial band (Gerdy’s tub.)
Pes tendons (sar, grac, semi)
Lateral collateral lig. (LCL) Semimembranosus (postmed.)
Popliteus (posteriorly)
INSERTIONS Ligaments:

Adductor magnus (ad- Biceps femoris Medial collateral lig. (MCL)
ductor tub.) Ligaments:
Ligaments:
Medial collateral Lateral collateral lig. (LCL)
Popliteofibular ligament
lig. (MCL) Arcuate ligament
Fabellofibular ligament

314 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

MUSCLES • Leg/Knee 9

Deep fascia of leg Interosseous membrane
Anterior compartment Tibia
Anterior intermuscular septum
Lateral compartment Deep posterior compartment

Fibula Transverse intermuscular Anterolateral
Posterior intermuscular septum septum incision

Deep fascia of leg Superficial posterior

comparatment Medial

incision

Cross section just above middle of leg

Tibialis anterior muscle Anterior tibial artery and veins
Extensor hallucis longus muscle and deep fibular (peroneal) nerve
Extensor digitorum longus muscle
Superficial fibular (peroneal) nerve Tibia
Anterior intermuscular septum Interosseous membrane

Great saphenous vein
and saphenous nerve

Deep fascia of leg Tibialis posterior muscle

Fibularis (peroneus) longus muscle Flexor digitorum longus muscle

Fibularis (peroneus) brevis muscle Fibular (peroneal) artery and veins

Posterior intermuscular septum Posterior tibial artery and veins
and tibial nerve
Fibula
Lateral sural cutaneous nerve Flexor hallucis longus muscle
Transverse intermuscular septum
Deep fascia of leg
Soleus muscle Plantaris tendon
Gastrocnemius muscle (lateral head)
Gastrocnemius muscle (medial head)
Sural communicating branch Medial sural cutaneous nerve
of lateral sural cutaneous nerve Small saphenous vein

COMPARTMENT MUSCLES NEUROVASCULAR STRUCTURE
Anterior
COMPARTMENTS (4)
Lateral
Superficial posterior Tibialis anterior (TA) Deep peroneal nerve
Deep posterior Extensor hallucis longus (EHL) Anterior tibial artery and vein
Extensor digitorum longus (EDL)
Anterolateral Peroneus tertius
Medial
Peroneus longus Superficial peroneal nerve
Peroneus brevis

Gastrocnemius None
Soleus
Plantaris

Posterior tibialis (PT) Tibial nerve
Flexor hallucis longus (FHL) Posterior tibial artery and vein
Flexor digitorum longus (FDL) Peroneal artery and vein
Popliteus

FASCIOTOMIES

Centered over the intermuscular septum between the anterior and lateral compartments

Centered over the posterior tibial border/septum between the superficial and deep
posterior compartments

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 315

9 Leg/Knee • MUSCLES Vastus medialis muscle
Patella
Vastus lateralis muscle Superior medial genicular artery
Rectus femoris tendon (becoming Tibial collateral ligament
quadriceps femoris tendon) Medial patellar retinaculum
Inferior medial genicular artery
Iliotibial tract Infrapatellar branch (cut) of
Superior lateral genicular artery Saphenous nerve (cut)
Joint capsule
Lateral patellar retinaculum Patellar ligament
Biceps femoris tendon Insertion of sartorius muscle
Tibial tuberosity
Inferior lateral genicular artery Tibia
Common fibular (peroneal) nerve
Gastrocnemius muscle
Head of fibula
Soleus muscle
Fibularis (peroneus) longus muscle
Extensor hallucis longus muscle
Tibialis anterior muscle

Superficial fibular (peroneal) nerve (cut)

Fibularis (peroneus) brevis muscle

Extensor digitorum longus muscle

Fibula Medial malleolus
Superior extensor retinaculum Tibialis anterior tendon
Medial branch of deep fibular (peroneal) nerve
Lateral malleolus Extensor hallucis longus tendon
Inferior extensor retinaculum Extensor hallucis brevis tendon
Extensor digitorum longus tendons Dorsal digital branches
Fibularis (peroneus) tertius tendon of deep fibular (peroneal) nerve
Extensor digitorum brevis tendons

Dorsal digital nerves

MUSCLE ORIGIN INSERTION NERVE ACTION COMMENT

Tibialis anterior Proximal lateral ANTERIOR COMPARTMENT
(TA) tibia, (Gerdy’s
tubercle) Med. cuneiform, plantar Deep Dorsiflex, invert Test L4 motor
Extensor hallucis foot function
longus (EHL) Medial fibula, 1st metatarsal base peroneal
interosseous
Extensor digito- membrane Base of distal phalanx of Deep Dorsiflex, extend Test L5 motor
rum longus
(EDL) Lateral tibia con- great toe peroneal great toe function
Peroneus tertius dyle & proximal
fibula Base of middle & distal Deep Dorsiflex, extend Single tendon
lateral 4 toes divides into
Distal fibula, phalanges (4 toes) peroneal four tendons
interosseous Dorsiflex, evert
membrane Base of 5th metatarsal Deep foot (weak) Often adjoined
peroneal to the EDL

316 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Biceps Long head MUSCLES • Leg/Knee 9
femoris Short head
muscle Tendon Vastus lateralis muscle
Iliotibial tract
Fibular collateral ligament Quadriceps femoris tendon
Superior lateral genicular artery
Common fibular Patella
(peroneal) nerve
Lateral patellar retinaculum
Inferior lateral
genicular artery Lateral condyle of tibia
Patellar ligament
Head of fibula Tibial tuberosity
Gastrocnemius muscle
Tibialis anterior muscle
Soleus muscle
Extensor digitorum longus muscle
Fibularis (peroneus) longus
muscle and tendon Superficial fibular
(peroneal) nerve (cut)
Fibularis (peroneus) brevis
muscle and tendon Extensor digitorum longus tendon
Extensor hallucis longus muscle and tendon
Fibula Superior extensor retinaculum
Inferior extensor retinaculum
Lateral malleolus Extensor digitorum brevis muscle

Calcaneal (Achilles) tendon Extensor hallucis longus tendon
Extensor digitorum longus tendons
(Subtendinous) bursa Fibularis (peroneus) brevis tendon
of tendocalcaneus Fibularis (peroneus) tertius tendon
Superior fibular 5th metatarsal
(peroneal) retinaculum bone

Inferior fibular
(peroneal) retinaculum
Fibularis (peroneus) longus
tendon passing to sole of foot

MUSCLE ORIGIN INSERTION NERVE ACTION COMMENT

Peroneus Proximal lateral LATERAL COMPARTMENT Plantar flex foot Test S1 motor func-
longus fibula (1st ray) tion; runs under the
Plantar medial cu- Superficial foot
Peroneus Distal lateral neiform, 1st meta- peroneal Evert foot
brevis fibula tarsal base Can cause avulsion fx
at base of 5th MT;
Base of 5th meta- Superficial has most distal
tarsal peroneal muscle belly

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 317

9 Leg/Knee • MUSCLES Iliotibial tract
Biceps femoris muscle
Semitendinosus muscle Tibial nerve
Semimembranosus muscle Common fibular (peroneal) nerve
Superior lateral genicular artery
Gracilis muscle Plantaris muscle
Popliteal artery and vein Gastrocnemius muscle (lateral head)
Lateral sural cutaneous nerve (cut)
Sartorius muscle Medial sural cutaneous nerve (cut)
Superior medial genicular artery
Gastrocnemius muscle (medial head)

Nerve to soleus muscle

Small saphenous vein

Gastrocnemius muscle

Soleus muscle Soleus muscle
Plantaris tendon

Flexor digitorum longus tendon Fibularis (peroneus) longus tendon
Tibialis posterior tendon Fibularis (peroneus) brevis tendon
Calcaneal (Achilles) tendon
Posterior tibial artery and vein Lateral malleolus
Tibial nerve Superior fibular (peroneal) retinaculum
Fibular (peroneal) artery
Medial malleolus Calcaneal branches of fibular (peroneal) artery
Flexor hallucis longus tendon Calcaneal tuberosity

Flexor retinaculum
Calcaneal branch of
posterior tibial artery

MUSCLE ORIGIN INSERTION NERVE ACTION COMMENT
Gastrocnemius
Soleus SUPERFICIAL POSTERIOR COMPARTMENT Test S1 motor function; two
Plantaris heads, fabella is in tendon
Lateral and me- Calcaneus Tibial Plantar flex foot of lateral head
dial femoral (via Achilles
condyles tendon) Fuses to gastrocnemius at
Achilles tendon
Posterior fibular Calcaneus Tibial Plantar flex foot
Long tendon can be harvested
head/soleal line (via Achilles for tendon reconstruction

of tibia tendon)

Lateral femoral Calcaneus Tibial Plantar flex foot
supracondylar (weak)
line

318 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Superior medial genicular artery MUSCLES • Leg/Knee 9
Gastrocnemius muscle (medial head) (cut)
Superior lateral genicular artery
Sural (muscular) branches Plantaris muscle (cut)
Popliteal artery and tibial nerve Gastrocnemius muscle (lateral head) (cut)
Fibular collateral ligament
Tibial collateral ligament Biceps femoris tendon (cut)
Semimembranosus tendon (cut) Inferior lateral genicular artery
Inferior medial genicular artery Head of fibula
Common fibular (peroneal) nerve
Popliteus muscle
Posterior tibial recurrent artery Soleus muscle (cut and reflected)
Tendinous arch of soleus muscle
Anterior tibial artery
Posterior tibial artery
Fibular (peroneal) artery
Flexor digitorum longus muscle
Flexor hallucis longus muscle (retracted)
Tibial nerve
Fibular (peroneal) artery
Tibialis posterior muscle Interosseous membrane

Calcaneal (Achilles) tendon (cut) Perforating branch of fibular

Flexor digitorum longus tendon Communicating branch (peroneal) artery
Tibialis posterior tendon
Fibularis (peroneus) longus tendon
Medial malleolus and posterior medial
malleolar branch of posterior tibial artery Fibularis (peroneus) brevis tendon
Lateral malleolus and posterior lateral
Flexor retinaculum malleolar branch of fibular (peroneal) artery
Medial calcaneal branches of Superior fibular (peroneal) retinaculum
posterior tibial artery and tibial nerve Lateral calcaneal branch
of fibular (peroneal) artery
Tibialis posterior tendon Lateral calcaneal branch of sural nerve
Medial plantar artery and nerve
Lateral plantar artery and nerve Inferior fibular (peroneal) retinaculum

Flexor hallucis longus tendon Fibularis (peroneus) brevis tendon
1st metatarsal bone
Fibularis (peroneus) longus tendon
Flexor digitorum longus tendon
5th metatarsal bone

MUSCLE ORIGIN INSERTION NERVE ACTION COMMENT

Popliteus DEEP POSTERIOR COMPARTMENT Origin is intraarticular;
primary restraint to
Flexor hallucis Lateral femoral con- Proximal poste- Tibial IR tibia/knee (dur- ER of knee
longus (FHL) dyle (anterior and rior tibia ing “swing” Test S1 motor function
distal to LCL) phase)
Flexor digitorum At ankle, tendon is
longus (FDL) Posterior fibula Base of distal Tibial Plantar flex great just anterior to tibial
phalanx of toe artery
Tibialis posterior great toe Tendon rupture/
(TP) degen. can cause
Posterior tibia Bases of distal Tibial Plantar flex lateral acquired flat foot
phalanges of 4 toes
4 toes

Posterior tibia, fibula, Plantar navicular Tibial Plantar flex and in-

interosseous mem- cuneiforms, MT vert foot (in “heel

brane bases off” phase)

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 319

9 Leg/Knee • NERVES

Infrapatellar branch
of saphenous nerve

Medial cutaneous nerves
of leg (branches of
saphenous nerve)

Tibial nerve

LUMBAR PLEXUS Tibial nerve Common
(L4, 5, S1, 2, 3) fibular
Posterior Division (peroneal)
Medial sural nerve
Saphenous (L2-4): Branch of femoral cutaneous nerve (cut)
nerve, enters leg posteromedially, Articular
superficial to sartorial fascia (at risk Articular branches branch
in direct medial approach, e.g.,
MMR). It then gives off infrapatellar Plantaris muscle Lateral sural
branch (at risk in anteromedial & cutaneous
midline approaches, e.g., ACLR), Gastrocnemius nerve (cut)
and descends in medial leg. muscle (cut)

Sensory: Infrapatellar region: via Nerve to popliteus muscle
infrapatellar branch
Medial leg: via medial Popliteus muscle
cutaneous nerves
Interosseous nerve of leg
Motor: None (in leg)
Soleus muscle (cut and
SACRAL PLEXUS partly retracted)

Anterior Division Flexor digitorum
longus muscle
Tibial (L4-S3): descends b/w heads
of gastrocnemius into leg, posterior Tibialis posterior muscle
to posterior tibialis muscle (in deep
posterior compartment) to ankle just Flexor hallucis
posterior to medial malleolus b/w longus muscle
FDL and FHL tendons. Sural nerve (cut)

Sensory: Proximal posterolateral leg: Lateral calcaneal branch
via medial sural nerve (from sural n.)
Medial calcaneal
Motor: • Super. post. compartment branch (from tibial n.)
‫ ؠ‬Plantaris
‫ ؠ‬Gastrocnemius Flexor retinaculum (cut)
‫ ؠ‬Soleus: via n. to soleus
Lateral dorsal
• Deep post. compartment cutaneous nerve
‫ ؠ‬Popliteus: via n. to
popliteus
‫ ؠ‬Posterior tibialis (PT)
‫ ؠ‬Flexor digitorum longus
‫ ؠ‬Flexor hallucis longus

320 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

NERVES • Leg/Knee 9

Cutaneous
innervation

From Common fibular Lateral sural
sciatic (peroneal) nerve cutaneous
nerve via lateral sural nerve
cutaneous nerve
Superficial
Medial sural fibular
cutaneous nerve (peroneal)
nerve
Superficial fibular
SACRAL PLEXUS (peroneal) nerve

Posterior Division Sural nerve

Common peroneal (L4-S2): divides Tibial nerve
from sciatic nerve in distal posterior via medial
thigh, runs posteroinferior to biceps calcaneal
femoris, around fibular neck (can be branches
compressed or injured), then divides
into 2 branches. Common fibular Common Peroneal Nerve
(peroneal) nerve
Sensory: Proximal lateral leg: via (phantom) Lateral sural
lateral sural nerve cutaneous nerve
Biceps femoris (phantom)
Motor: None (before dividing) tendon Articular branches
Recurrent
Deep peroneal: runs in anterior com- Common fibular articular nerve
partment of leg with anterior tibial (peroneal) nerve Extensor digitorum
artery, posterior to tibialis anterior (L4, 5, S1, 2) longus muscle (cut)
on interosseous membrane. Deep fibular
Head of fibula (peroneal) nerve
Sensory: None (in leg) Tibialis
Motor: • Anterior compartment Fibularis anterior muscle
(peroneus)
‫ ؠ‬Tibialis anterior (TA) longus muscle Extensor digitorum
‫ ؠ‬Extensor hallucis longus (cut) longus muscle
‫ ؠ‬Ext. digitorum longus
‫ ؠ‬Peroneus tertius Superficial fibular Extensor hallucis
(peroneal) nerve longus muscle
Superficial peroneal: Runs in lateral
compartment of leg, crosses anteri- Branches of Lateral branch of
orly 12cm above lateral malleolus (in- lateral sural deep fibular
jured in lateral ankle approach, e.g., cutaneous (peroneal) nerve to
ankle ORIF) to dorsal foot, then di- nerve Extensor hallucis brevis
vides into 2 branches. Fibularis and
(peroneus) Extensor digitorum
Sensory: Anterolateral leg longus muscle brevis muscles
Motor: • Lateral compartment
Fibularis Medial branch of
‫ ؠ‬Peroneus longus (PL) (peroneus) deep fibular
‫ ؠ‬Peroneus brevis (PB) brevis muscle (peroneal) nerve

Other Medial dorsal
cutaneous nerve
Sural: Formed from medial sural cu-
taneous (tibial nerve) & lateral sural Intermediate dorsal
cutaneous (peroneal nerve), runs cutaneous nerve
subcutaneously in posterolateral leg,
crosses Achilles tendon 10cm above Inferior extensor
insertion, then to lateral heel. retinaculum
(partially cut)
Sensory: Posterolateral distal leg
Motor: None Lateral dorsal
cutaneous nerve
(branch of sural
nerve)

Dorsal digital nerves

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 321

9 Leg/Knee • ARTERIES Descending genicular artery
Articular branch
Femoral artery passing Saphenous branch
through adductor hiatus
Superior medial genicular artery
Superior lateral genicular artery
Patellar anastomosis Popliteal artery (phantom)

Inferior lateral genicular artery Middle genicular artery (phantom)
(partially in phantom)
Posterior tibial recurrent artery Inferior medial genicular artery
(phantom) (partially in phantom)

Circumflex fibular branch Anterior tibial recurrent artery
Anterior tibial artery
Posterior tibial artery (phantom)
Interosseous membrane
Fibular (peroneal) artery (phantom)

COURSE BRANCHES COMMENT/SUPPLY

POPLITEAL ARTERY

Begins at adductor hiatus and runs Superior medial and lateral geniculate SLGA at risk in lateral release
through the popliteal fossa, posterior Inferior medial and lateral geniculate ILGA separates lateral knee layer 3
to PCL (can be injured here), then ligaments/structures
divides at the popliteus muscle Middle geniculate Supplies ACL, PCL, and synovium
Anterior and posterior tibial arteries Terminal branches of popliteal artery

• All four geniculate arteries anastomose around the knee and the patella.

ANTERIOR TIBIAL ARTERY

Passes b/w the two heads of the Anterior tibial recurrent Supplies and anastomoses at knee
posterior tibialis into the anterior Circumflex fibular Supplies fibular head and lateral knee
compartment and lies on interosse- Anterior medial and lateral malleolar Supplies anterior portion of malleoli
ous membrane w/deep peroneal n. Dorsalis pedis Terminal branch in foot

• Supplies muscles of the anterior compartment of the leg

POSTERIOR TIBIAL ARTERY

Runs with tibial nerve in deep poste- Posterior tibial recurrent Supplies and anastomoses at knee
rior compartment, posterior to pos- Peroneal artery Supplies lateral compartment
terior tibialis muscle to the ankle, Perforating muscular branches To muscles of post. compartments
where it lies between the FDL and Posterior medial malleolar Supplies posterior medial malleolus
FHL tendons posterior to the medial Medial calcaneal Supplies medial calcaneus/heel
malleolus (pulse is palpable here). Medial and lateral plantar Terminal branches in the foot

• Supplies muscles of the superficial and deep posterior compartments of the leg

PERONEAL ARTERY

Branches from posterior tibial artery, Posterior lateral malleolar Supplies posterior lateral malleolus
runs between PT & FHL muscles in Lateral calcaneal Supplies lateral calcaneus/heel
posterior compartment

• Supplies muscles of the lateral compartment of the leg

• See muscle pages 315-319 for additional pictures of the arteries

322 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Progressive DISORDERS • Leg/Knee 9
stages in
joint Joint Pathology in Osteoarthritis
pathology

Knee joint opened anteriorly Early degenerative Further erosion of Cartilages almost completely
reveals large erosion of articular changes with surface cartilages, pitting, and destroyed and joint space
cartilages of femur and patella fraying of articular cleft formation. Hyper- narrowed. Subchondral bone
with cartilaginous excrescences cartilages trophic changes of bone irregular and eburnated; spur
at intercondylar notch at joint margins formation at margins. Fibrosis
of joint capsule

Joint Pathology in Rheumatoid Arthritis

1 2 34 Knee joint opened anteriorly, patella
reflected downward. Thickened
Progressive stages in joint pathology.1. Acute inflammation of synovial membrane synovial membrane inflamed; poly-
(synovitis) and beginning proliferative changes. 2. Progression of inflammation with poid outgrowths and numerous villi
pannus formation; beginning destruction of cartilage and mild osteoporosis. 3. Sub- (pannus) extend over rough articular
sidence of inflammation; fibrous ankylosis. 4. Bony ankylosis; advanced osteoporosis cartilages of femur and patella

DESCRIPTION Hx & PE WORKUP/FINDINGS TREATMENT

• Primary/idiopathic or sec- ARTHRITIS 1. NSAIDs, activity modification
ondary (e.g., posttrau- 2. Physical therapy, brace, cane
matic) Osteoarthritis 3. Glucocorticosteroid injections
4. Unicompartmental
• Loss/deterioration of ar- Hx: Older, decreasing XR
ticular cartilage activity level. Pain w/ ‫ ؠ‬HTO
weight-bearing and 1. Arthritis series ‫ ؠ‬Unicompartment arthroplasty
• Can affect 1 (medial #1) activities ‫ ؠ‬Joint space narrowing 5. Tricompartmental: Total knee
or all 3 compartments in PE: Effusion, joint line ‫ ؠ‬Osteophytes arthroplasty (TKA)
knee tenderness, ϩ/Ϫ con- ‫ ؠ‬Subchondral sclerosis
tracture or deformity ‫ ؠ‬Subchondral cysts 1. Early: manage medically
• Multiple types: rheuma- (varus #1) 2. Late
toid, gout, seronegative 2. Alignment views
(e.g., Reiter’s) ‫ ؠ‬Nonop: like osteoarthritis
Inflammatory ‫ ؠ‬Synovectomy
• In RA, synovitis/pannus ‫ ؠ‬Total knee arthroplasty
formation destroys carti- Hx: Usually younger XR: Arthritis series: joint
lage & eventually whole pts. Pain, often multi- narrowing, joint ero-
joint. ple joints sions, ankylosis, joint
PE: Effusion, ϩ/Ϫ destruction
warmth, decr. ROM & LABS: CBC, RF, ANA, CRP,
deformity crystals, culture

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 323

9 Leg/Knee • DISORDERS

Patellofemoral stress syndrome

With knee extended, patella As knee flexes, tension
lies above and between in quadriceps femoris
femoral condyles in contact tendon and patellar tendon
with suprapatellar fat pad compresses patella against
femoral condyles

Chondromalacia

Arthroscopic view shows Chondromalacia of patella with Iliotibial tract friction
fragmented patellar cartilage “kissing” lesion on femoral condyle syndrome
Lateral patellar compression syndrome As knee flexes and
extends, iliotibial tract
Patella glides back and forth
over lateral femoral
epicondyle, causing
friction

Preoperative x-ray showing lateral Lateral patellar Arthroscopic view of transcutaneous
tilt of patella. retinaculum release of lateral retinaculum

Line indicates extent of release

DESCRIPTION Hx & PE WORKUP/FINDINGS TREATMENT

ANTERIOR KNEE PAIN • NSAIDs, activity modification
• Physical therapy: ROM,
Patellofemoral Syndrome
quad. strengthening, ham-
• Pain in patellofemoral joint Hx: Young female XR: 4 views: string stretching, ϩ/Ϫ foot
• Contributing factors: overuse, and athletes. Pain AP & notch: eval. for orthoses
w/activities (esp. run- OCD, OA • Patella realignment
subtle instability or malalign- ning, stairs) and pro- Lateral: OA & Insall (if malalignment is present)
ment, quadriceps weakness longed sitting ratio
• Chondromalacia may be PE: ϩpatella compres- Sunrise: subluxation or • NSAIDs, activity modification
present, but not necessarily sion, ϩ/Ϫ incr. • Physical therapy
Q angle and/or J-sign tilt, OA, OCD • Arthroscopic debridement/

Chondromalacia Patellae chondroplasty may help

• Softening or wear of the ar- Hx: Usually younger pts.; XR: 4 view: evaluate • PT: stretch lateral tissues,
ticular cartilage of the patella pain, often multiple jts. like PFS (see above) quad. strengthening ϩ/Ϫ
PE: Effusion, decr. ROM taping or centralizing brace
• Term often misused to imply & deformity
any anterior knee pain • Arthroscopic lateral release

Lateral Patellar Compression Syndrome • NSAIDs, activity modifica-
tion, stretching (ITB)
• Overloading of lateral facet Hx: Usually younger pts.; XR: 3 or 4 views
during flexion anterior knee pain Sunrise/merchant: • Partial excision (rare)
PE: PF pain, decreased evaluate for lateral
• Due to tight lateral structures mobility/patella glide patella tilt
(esp. lateral retinaculum)

Iliotibial Band Syndrome

• ITB rubs on lateral femoral Hx: Pain w/activity XR: AP/lateral: normal,
condyle
PE: Lateral femoral con- r/o tumor
• Common w/runners/cyclists
dyle; TTP (knee at 30°)

324 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

DISORDERS • Leg/Knee 9

Patella (turned up) Synovial plica
Opening to suprapatellar pouch

Medial femoral Suprapatellar plica (usually
condyle asymptomatic)

Lateral gutter

Lateral plica (asymptomatic)

Medial (shelf) Lateral femoral condyle 30˚
plica (symptomatic) At 30˚ flexion,
Anterior cruciate ligament
plica sweeps across
Infrapatella plica
Tibia condyle. May cause
Fibula
pain and condylar erosion

Lateral Subluxation and dislocation of patella Medial retinaculum/medial
retinaculum patellofemoral ligament torn
Medial
Medial retinaculum
retinaculum stretched

Skyline view. Normally, patella rides In subluxation, patella deviates laterally; can be In dislocation, patella
in groove between medial and lateral due to weakness of vastus medialis muscle, displaced completely out
femoral condyles tightness of lateral retinaculum, and high Q angle of intercondylar groove

DESCRIPTION Hx & PE WORKUP/FINDINGS TREATMENT

• Subluxation or disloca- ANTERIOR KNEE PAIN • Acute: MPFL repair
tion of patella (lateral #1) • Recurrent/chronic:
Patellar Instability
• Associated w/anatomic physical therapy, brace;
variants Hx: Pain & patella instability XR: 3 or 4 views: eval. patellar realignment
PE: ϩ patellar apprehension, for fx and patella posi- surgery
• MPFL is key structure ϩ/Ϫ increased Q angle, tion (lateral and/or pa-
genu valgum, femoral an- tella alta) • NSAIDs, stretch and
• Seen in jumpers (e.g., teversion MR: eval. MPFL if acute strengthen quadriceps
basketball/volleyball and hamstrings
players) Patellar Tendinitis
• Surgical debridement
• Microtears at tendon in- Hx: Sports, anterior knee XR: AP/lateral: normal (rare)
sertion at distal pole pain (worse with activity) MR: Increased signal at
PE: Patellar inferior pole TTP insertion (inferior pole) • Ice, NSAIDs
• Fold in synovium (embry- or intrasubstance • Activity modification
onic remnant) becomes • Arthroscopic debridement
thickened or inflamed Plica
(if symptoms persist)
• Medial plica #1 Hx: Anteromedial pain, ϩ/Ϫ XR: Knee series. Eval. for
popping/catching other pain sources • Inflammatory: ice, NSAIDs,
• Etiology: trauma or over- PE: Tender, palpable plica, MR: Of questionable knee pads, rest, ϩ/Ϫ
use (e.g., prolonged ϩ/Ϫ snap with flexion value aspiration; bursectomy if
kneeling) persistent
Prepatellar Bursitis
• ”Housemaid’s knee” • Septic: bursectomy, abx
• Inflammatory or septic Hx: Knee pain & swelling XR: Knee series: usu.
PE: Egg-shaped swelling on normal
anterior patella, TTP, ϩ/Ϫ LAB: CBC, ESR, ϩ/Ϫ as-
signs of infection pirate: gram stain & cell
count

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 325

9 Leg/Knee • DISORDERS

Rupture of Anterior Cruciate Ligament

Posterior cruciate ligament
Anterior cruciate ligament
(ruptured)

Arthroscopic view Terrible Triad
Rupture of medial collateral
and anterior cruciate ligaments
plus tear of medial meniscus

DESCRIPTION Hx & PE WORKUP/FINDINGS TREATMENT

LIGAMENT INJURIES

Anterior Cruciate

• Mechanism: twisting injury, Hx: Twisting injury, XR: Knee series (Segond fx Based on functional stability
often noncontact pivoting “pop,” swelling, inabil- is pathognomic for ACL) ‫ ؠ‬Stable/low demand pt:
ity to continue playing MR: Absent/detached ACL, activity modification, PT,
• Associated with other inju- PE: Effusion (hemarthro- ϩ/Ϫ bone bruise (middle brace
ries: meniscal tears, collat- sis) ϩ Lachman (most LFC–posterior lateral tibia ‫ ؠ‬Unstable/athletes/active
eral ligament (all 3 ϭ ter- sensitive), ϩ anterior plateau) pt: surgical reconstruc-
rible triad) drawer, ϩ pivot shift Arthrocentesis: Hemar- tion (grafts: BTB, ham-
throsis string, allograft )
• Common in female ath-
letes

COMPLICATIONS: arthrofibrosis, failure/recurrence (1. technical error, 2. missed ligamentous injury, 3. recurrent trauma)

Posterolateral Corner

• Mechanism: direct blow or Hx: Trauma, pain, insta- XR: Knee series. Avulsions • Nonoperative: low grade
hyperextension/varus injury bility can occur (fibular head). (grades 1& 2 injury):
PE: ϩ/Ϫ effusion, ϩ Alignment: eval. for varus brace & physical therapy
• LCL, popliteus, popliteofib- prone ER test at 30°, MR: To evaluate all liga-
ular ligament are injured. ϩ/Ϫ posterolateral ments and other soft • Surgical repair: acute
These are focus of surgical drawer & ER recurva- tissues grade 3
reconstruction. tum tests
• Surgical reconstruction:
• Can be associated w/PCL chronic or combined in-
injury jury, HTO if varus

326 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

DISORDERS • Leg/Knee 9

Rupture of posterior cruciate ligament

Demonstration of
hyperextension

Posterior sag sign. Leg drops backward

Collateral ligament injury

1st-degree sprain. Localized 2nd-degree sprain. Detectable 3rd-degree sprain. Complete
joint pain and tenderness but joint laxity with good end point disruption of ligaments
no joint laxity plus localized pain and tenderness and gross joint instability

DESCRIPTION Hx & PE WORKUP/FINDINGS TREATMENT

• Mechanism: anterior LIGAMENT INJURIES • Nonoperative: isolated
force on tibia (e.g., dash- (esp. grades 1& 2 injury):
board injury) or sports Posterior Cruciate brace & PT
(hyperextension)
Hx: Trauma (dashboard) or XR: Knee series. Look for • Surgical reconstruction:
• Associated with collateral sports injury, pain avulsion fracture. failed nonop treatment,
and/or PL corner injuries PE: ϩ/Ϫ effusion, ϩ poste- MR: Confirms diagnosis. combined injury, some
rior drawer, quadriceps Evaluates meniscus and isolated grade 3’s
• Mechanism: valgus force active test, & posterior articular cartilage.
• Common in football sag • Hinged knee brace
• Usually injured at femoral • Physical therapy: ROM
Medial Collateral
origin (medial epicondyle) and strengthening
Hx: Trauma, pain, instability XR: Knee series. Medial • Surgery: uncommon
• Mechanism: varus force PE: Tenderness at medial epicondyle avulsion
• Isolated injuries are rare, epicondyle along tendon. can occur (calcified ϭ • Isolated injury: hinged
Pain/laxity w/valgus stress Pelligrini-Steida). brace
usually combined with MR: Confirms diagnosis
posterolateral corner (PLC) • Combined injury: surgical
Lateral Collateral repair or reconstruction

Hx: Trauma, pain, instability XR: Knee series. Fibular

PE: Lateral tenderness. head avulsions can occur.

Pain/laxity w/varus stress MR: Confirms diagnosis

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 327

9 Leg/Knee • DISORDERS

Tears of meniscus

Anterior Femoral
cruciate condyle
ligament

May progress to

Longitudinal (vertical) tear Bucket handle tear Bucket
handle

Arthroscopic view of bucket handle
tear shows handle displaced into
intercondylar fossa

May progress to

Radial tear Parrot beak tear Arthroscopic view of parrot beak tear
Osteochondral defect with fibrillation of meniscal margin

Stage 2
lesion

Fragment of cartilage and bone Tunnel view radiographs of small OCD Arthroscopic view of knee
lesion involving medial femoral condyle with osteochondral defect

DESCRIPTION Hx & PE WORKUP/FINDINGS TREATMENT

• Acute: young, twisting injury INTRAARTICULAR CONDITIONS • Small/minimally symptom-
• Degenerative: older ϩ/Ϫ OA atic: treat conservatively
• Multiple tear patterns Meniscus Tear
• Associated w/other injuries • Peripheral tears (red
Hx: Pain & swelling XR: Knee series: usually zone): repair (heal best
(ACL rupture, OCD, etc) esp. with flexion ac- normal. Early OA w/ACL reconstruction)
• MedialϾlateral 3:1 (poste- tivities, ϩ/Ϫ catching often seen in pts
or locking (e.g., w/degenerative tears • Central tears (white zone):
rior horn most common) bucket handle tear) MR: Very sensitive for partial meniscectomy
PE: Effusion, joint line tears. “Double PCL” sign
• Spectrum: purely chondral tenderness, ϩ for displaced bucket han- Displaced OCD: internal
to osteochondral lesions McMurray/Apley tests dle tears fixation
Chondral:
• Traumatic or degenerative Osteochondral Defect ‫ ؠ‬Debridement
• Osteochondritis dissecans is ‫ ؠ‬Microfracture
Hx: Often young/active XR: Knee series: 4 views ‫ ؠ‬Osteochondral transfer
separate but similar entity pts. Pain (usually (need 45° PA & notch ‫ ؠ‬Chondrocyte implantation
w/WB), ϩ/Ϫ popping, views), consider align-
catching ment series
PE: Inconsistent: ϩ/Ϫ MR: Good modality for
effusion, bony ten- purely chondral lesions
derness

328 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

DISORDERS • Leg/Knee 9

Quadriceps tendon rupture

Rupture of quadriceps femoris
tendon at superior margin of
patella

Torn retinaculum closed
with interrupted sutures

Patellar tendon rupture

Rupture of patellar ligament
at inferior margin of patella

Ruptured patellar ligament
repaired with nonabsorbable
sutures through drill holes
in patella; torn edges of
retinaculum approximated
with interrupted sutures

DESCRIPTION Hx & PE WORKUP/FINDINGS TREATMENT

OTHER

Quadriceps Tendon Rupture

• Mechanism: eccentric Hx: Older, fall/trauma XR: Knee series. Look for • Acute: primary surgical
contraction or indirect PE: Effusion, palpable de- patella baja repair
trauma fect above patella. Inabil- MR: Will show tendon tear.
ity to do or maintain Usually not needed. May • Chronic: surgical recon-
• Patients usually Ͼ40y.o. straight leg raise be helpful in partial tears. struction (tendon length-
• Usually at musculotendi- ening or allograft proce-
dure)
nous junction

Patellar Tendon Rupture

• Mechanism: direct or in- Hx: Younger pts, trauma, XR: Knee series. Look for • Acute: primary surgical
direct (eccentric load) pain, loss of knee patella alta repair
trauma extension MR: Will show tendon tear.
PE: Effusion, palpable de- Usually not needed. May • Chronic: surgical recon-
• Patients usually Ͻ40y.o. fect in tendon. Cannot do be helpful in partial tears. struction (tendon length-
• Associated with underly- straight leg raise ening or allograft proce-
dure)
ing tendon and/or meta-
bolic disorder

Tumor

#1 in adolescents: osteosarcoma; #1 in adults: chondrosarcoma; #1 benign (young adults): giant cell tumor

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 329

9 Leg/Knee • DISORDERS

TOTAL KNEE ARTHROPLASTY

General Information

• Goals: 1. Clinical: alleviate pain, maintain personal independence, allow performance of activities of daily living (ADLs)
& recreation; 2. Surgical: restore mechanical alignment, restore joint line, balance soft tissues (e.g., collateral ligs.)

• Common procedure with high satisfaction rates for primary procedure. Revisions are also becoming more common.
Advances in techniques and materials are improving implant survival; this procedure now available to younger pts.

Materials and Designs

Materials
• Femur component: cobalt-chrome commonly used for femoral-bearing surface with titanium stem
• Tibia component/tray: does not articulate with femoral component. Often made of titanium.
• Tibial tray insert: articulates with femoral component; made of polyethylene (UHMWPE, ultra high molecular weight PE)

‫ ؠ‬Polyethylene (PE) wears well but does produce microscopic particles that may lead to implant loosening & failure.
‫ ؠ‬Polyethylene should be at least 8mm thick, cross-linked for better wear, & sterilized in inert (non-O2) environment.
‫ ؠ‬Congruent design (not flat) improves wear rate and rollback (increased knee flexion).
‫ ؠ‬Direct compression molding is preferred manufacturing technique.
• Cement: methylmethacrylate
Prosthetic Designs
• Unconstrained: 2 types. These are most common for primary surgical procedures with minimal deformity.
‫ ؠ‬Posterior cruciate (PCL) retaining (“CR”): preserves femoral rollback for incr. knee flexion but has incr. PE wear.
‫ ؠ‬Posterior cruciate (PCL) substituting (“posterior stabilized”) (“PS”): provides mechanical rollback, but may dislocate.

Indicated for patellectomy, inflammatory arthritis, incompetent PCL (e.g., previous PCL rupture, etc).
• Constrained (non-“hinged”): Used for moderate ligament (MCL/LCL) deficiency. Uses a central post to provide stability.
• Constrained (“hinged”): Used for global ligament deficiency. Has high wear and failure rates.
• Other: Mobile-bearing designs are available.
Fixation
• Cement. Most common.
• Biologic. Bone ingrowth techniques. Theoretically have longer life, but have higher failure rates.

Indications

• Arthritis of knee

‫ ؠ‬Common etiologies: osteoarthritis (idiopathic, posttraumatic), rheumatoid arthritis, osteonecrosis

‫ ؠ‬Clinical symptoms: knee pain, worse with activity, gradually worsening over time, decreased ambulatory capacity.

‫ ؠ‬Radiographic findings: appropriate radiographic evidence of knee arthritis

OSTEOARTHRITIS RHEUMATOID ARTHRITIS

1. Joint space narrowing 1. Joint space narrowing

2. Sclerosis 2. Periarticular osteoporosis

3. Subchondral cysts 3. Joint erosions

4. Osteophyte formation 4. Ankylosis

• Failed conservative treatment: NSAIDs, activity modification, weight loss, physical therapy, orthosis (e.g., medial off-

loader brace), ambulatory aid (e.g., cane in contralateral hand), injections (corticosteroid, viscosupplementation)

Contraindications

• Absolute: Neuropathic joint, infection, extensor mechanism dysfunction, medically unstable patient (e.g., severe car-
diopulmonary disease). Patient may not survive the procedure.

• Relative: Young, active patients. These patients can wear out the prostheses many times in their lives.

Alternatives

• Considerations: age, activity level, overall medical health

• Osteotomy: relatively young patients with unicompartmental disease
‫ ؠ‬Valgus knee/lateral compartment DJD: distal femoral varus–producing osteotomy
‫ ؠ‬Varus knee/medial compartment DJD: proximal tibia valgus–producing osteotomy

• Unicompartmental arthroplasty: unicompartmental disease

• Arthrodesis/fusion: young laborers with isolated unilateral disease (e.g., normal spine, hip, ankle)

330 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

All components DISORDERS • Leg/Knee 9
in place
Knee
extended

TOTAL KNEE ARTHROPLASTY

Procedure

Approaches
• Midline incision with medial parapatellar arthrotomy is most common.
• Minimally invasive incisions are also being used. Special equipment is often needed for the smaller incisions.
Steps
• Bone cuts

‫ ؠ‬Cut femur and tibia perpendicular to mechanical axis. Can use intramedullary (femur/tibia) or extramedullary (tibia)
reference; this will restore the mechanical alignment

‫ ؠ‬Bone removed from femur and tibia should be equal to that replaced by the implants to maintain/restore joint line.
• Implants—trial implants are first inserted to test adequacy of the bone cuts

‫ ؠ‬Implants should be best fit possible to native bone
‫ ؠ‬Femur placed in 3º of external rotation to accommodate a perpendicular bone cut of the proximal tibia (typically in

3º of varus)
‫ ؠ‬Femoral axis determined in 3 ways: 1. epicondylar axis, 2. posterior condylar axis, 3. AP axis—perpendicular to

trochlea
• Balancing

‫ ؠ‬Sagittal plane: goal is to make flexion & extension gaps equal. May need to cut more bone or add implant augments.
‫ ؠ‬Coronal plane: soft tissues are of primary concern. Rule is to release the concave side of the deformity.
‫ ؠ‬Varus deformity: release medial side: 1. deep MCL, 2. postmed capsule/semimemb insertion, 3.superficial MCL
‫ ؠ‬Valgus deformity: release lateral side: 1. lateral capsule, 2a. ITB (tight in ext.), 2b. popliteus (tight in flexion), 3. LCL
‫ ؠ‬Polyethylene trial: the knee should be stable and well balanced with the trial polyethylene in place.
• Final implantation of components

Complications

• Patellofemoral complications are most common: patella maltracking, patellofemoral pain, patellar fracture.
• Arthrofibrosis: may respond early (<6 wk) to manipulation under anesthesia.
• Extensor mechanism failure: patellar tendon rupture or avulsion (difficult to repair/reconstruct); patellar fracture
• Infection: diagnose with labs and aspiration. Prevention is mainstay: perioperative antibiotics, meticulous prep/drape

technique, etc. Treatment: acute/subacute: irrigation & debridement with PE exchange. Late: 1- or 2-stage revision
• Loosening: more common with biologic fixation. Also caused by microscopic particles from polyethylene wear
• Neurovascular injury

‫ ؠ‬Peroneal nerve: esp. after mechanical axis correction of a valgus knee (nerve is stretched)
‫ ؠ‬Superolateral geniculate artery: should be identified and cauterized
• Medical complications: Deep venous thrombosis (DVT) and pulmonary embolus (PE) are known risks of TKA.
Prophylaxis must be initiated.
• Periprosthetic fracture
‫ ؠ‬Femur: stable implant—nail or fixed angle device; unstable implant—replace with longer stem that passes fx site

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 331

9 Leg/Knee • PEDIATRIC DISORDERS

Genu varum and valgum
(bow leg and knock-knee)

Two brothers, younger (left) with bowleg, older (right)
with knock-knee. In both children, limbs eventually
became normally aligned without corrective treatment

Infantile tibia vara (Blount’s disease)

Unilateral
Bilateral

DESCRIPTION EVALUATION TREATMENT

• Normal (physiologic): ages 0-2 GENU VARUM • Physiologic: observation
• Pathologic: Blount’s disease: • Infantile: Ͻ3y.o.: brace; Ͼ3y.o.:
Hx: Parents notice a deformity
2 types PE: Unilateral or bilateral genu varum osteotomy
‫ ؠ‬Infantile: Ͻ3y.o., obesity, early XR: Tibia metadiaphyseal angle • Adolescent: hemiepiphysiodesis
(TMDA): Ͻ9° is normal, Ͼ16° is
walking pathologic/Blount’s (open physis) or osteotomy (closed
‫ ؠ‬Adolescent: insidious onset physis)
GENU VALGUM
Ͼ8y.o. • Physiologic: observation
Hx: Parents notice a deformity • Pathologic: hemiepiphysiodesis
• Normal (physiologic): ages 2-5 PE: Unilateral or bilateral genu valgum
• Pathologic: skeletal tumors XR: Alignment x-rays: valgus is 6° in or osteotomy
normal adults
‫ ؠ‬Metabolic: renal osteodystrophy
‫ ؠ‬Other: trauma, infection

332 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

PEDIATRIC DISORDERS • Leg/Knee 9

Posteromedial bowing of tibia

Posteromedial bowing.
Convexity of bow in distal third of
tibia and fibula directed posteriorly
and medially. Spontaneous
correction usually obviates need
for realignment osteotomy, but
leg-length discrepancy often
persistent.

Anterolateral bowing of tibia and congenital pseudarthrosis

Congenital pseudoarthrosis of the tibia.
Angulation of right leg. Café au lait spots
on thigh and abdomen suggest relationship
to neurofibromatosis.

Anterolateral bowing.
In infancy it may be difficult to
predict if anterolateral bowing
will correct spontaneously or
if bone will progress to fracture
and congenital pseudarthrosis.
Progression to pseudarthrosis
is more likely if the medullary
canal is narrow and has
sclerotic changes.

Anterolateral bowing. Medullary canal
present but narrow with sclerotic changes;
cyst apparent. Prone to spontaneous fracture
and pseudarthrosis

DESCRIPTION EVALUATION TREATMENT

TIBIA BOWING

Posteromedial Bowing

• Congenital convexity of tibia Hx: Deformity present at birth • Bowing resolves with growth
• Idiopathic, unilateral PE: Foot appears dorsiflexed (calca-
• Deformity corrects but a leg length neovalgus), leg is bowed • Resultant leg length discrepancy
XR: Bowing of tibia and fibula ‫ ؠ‬Mild: shoe lift
discrepancy usually results ‫ ؠ‬Severe: hemiepiphysiodesis

Anterolateral Bowing/Congenital Tibia Pseudarthrosis

• Bowing of tibia, unknown etiology Hx/PE: Leg deformity & disability. • Young/bowing tibia: full contact brace
• Associated with neurofibromatosis Bowed leg, ϩրϪ signs of neurofi- • Pseudarthrosis: tibial nail/external
• Anterolateral bowing can lead to bromatosis (e.g., café au lait spots)
XR: Reveals bowing or pseudarthrosis fixation & bone graft
pseudarthrosis • Amputation: if surgical treatment fails

NETTER’S CONCISE ORTHOPAEDIC ANATOMY 333