256200 PCPD FLIP PROOF

EXTRA-CAPSULAR CRUCIATE
REPAIR WET-LAB

Andrew Worth BVSc, PGDipVCS, FANZCVS, PhD.
Professor of Small Animal Surgery Massey University, Palmerston North, NZ

“BE A BETTER VET”

www.practicalcpd.co.nz



INTRODUCTION

1. Anatomy

– Stifle ligaments, role of the cranial cruciate
– Meniscal anatomy and relevance to meniscal injury

2. Diagnosis

– History, physical examination, manipulative tests
– Radiography

3. Surgical management of cruciate disease

– Principles
– History
– Late meniscal injuries


4. Evidence based decision making in cruciate disease
5. Meniscal surgery

– Medial and lateral arthrotomy
– Stifle arthroscopy

6. Traumatic stifle injury in working dogs



7. Cruciate disease in cats
8. Extracapsular technique

– Isometry
– Implant types

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Extracapsular Cruciate Technique Workshop 3

1. ANATOMY

The stifle is a diarthrodial, condylar joint. It primarily acts as a hinge point. These inevitably progress to partial then full tears as the
joint with a limited range of rotation. Varus/valgus deviation is degenerative process continues. By the time the acute final tearing
limited by collateral ligaments and the cruciate ligaments prevent occurs, which makes the drawer obvious, there is radiographic
cranial-caudal subluxation. The extensor mechanism of the stifle evidence of DJD.
acts through the femero-patellar joint leading to loading of the
femoro-tibial joint during weight-bearing. The menisci (medial Acute on chronic stifle injury in pet dogs
and lateral) act as shock absorbers, cup the femoral condyles
to transmit force between convex cartilage surfaces, have It has long been recognised that contrary to the athletic or injury
proprioceptive innervation, and spread the joint fluid into a uniform cause of most human ACL ruptures, many of our patients seem to
thin film. The lateral meniscus has attachments via ligaments undergo chronic degeneration and eventual rupture under minimal
to the femur and tibia, and can translate as the joint moves. The force. In the middle two groups above, the tearing of the cruciate
medial meniscus has attachments by ligaments to the tibia (cranial ligament occurs over a period of time before the drawer becomes
and caudal menisco-tibial ligaments) and the medial collateral evident to palpation. The exact etiopathogenesis is still the subject
ligament, and is less free to move. This is why it is the medial of debate with repetitive trauma, weight bearing stress, leptins, and
meniscus that is invariably injured when a CCLR occurs, as the lymphocytic/plasmocytic arthritis all being hypothesised to initiate
meniscus is pinched by the femur moving caudally. collagen injury.

The functions of the cranial cruciate ligament are: Cruciate disease is therefore not a single entity, rather at least three
distinct signalment groupings are identified:
●● p revention of cranial displacement of the tibia relative to
the femur, I. A cute traumatic tears in dogs without pre-existing DJD (often
working breeds)
●● l imitation of internal rotation of the tibia relative to the femur,
limiting hyperextension, II. C hronic ongoing degeneration resulting in CCLR in middle aged,
often over-weight, mostly de-sexed, medium to large breed dogs
●● a nd proprioception.
III. Y oung, giant breed dogs presented with bilateral disease
The cranial cruciate ligament consists of multiple bundles of fibres at less than 3 years of age. A genetic link has been found in
that arise on the medial aspect of the lateral femoral condyle Newfoundlands and warrants more investigation.
and insert on the tibial plateau. The CCL grossly consists of two
principle bands, which spiral about one another and are named Additionally there are dogs that suffer CCLR in association with
after their insertion – cranio-medial and caudo-lateral. The cranio- another pathology.
medial band is taut in flexion and extension, whereas the caudo-
lateral band is taut only in extension and is relaxed in flexion. IV. A ssociated with medial patellar luxation? OCD? (a cause and
effect link is unproven)
Cranial drawer represents cranial subluxation of the tibia in respect
to the femur (or caudal femoral translation in relation to the tibial It has long been recognised that contrary to the athletic or injury
plateau) and is elicited by manipulating the stifle during physical cause of most human ACL ruptures, many of our patients seem to
examination. Cruciate disease varies from acute rupture to chronic undergo chronic degeneration and eventual rupture under minimal
degeneration with gradual failure, followed by a terminal tear with force. In the middle two groups above, the tearing of the cruciate
minimal force. ligament occurs over a period of time before the drawer becomes
evident to palpation. The exact etiopathogenesis is still the subject
The cranio-medial band is commonly torn prior to failure of the of debate with repetitive trauma, weight bearing stress, leptins, and
caudo-lateral band. The resulting “partial” rupture can be missed lymphocytic/plasmocytic arthritis all being hypothesised to initiate
if an incomplete stifle manipulation is performed. Examination for collagen injury.
cranial drawer with the stifle in extension only will miss a diagnosis
of partial rupture. When the examiner tests for cranial drawer with Should the type of surgery performed be determined by the
the stifle joint in extension, the caudo-lateral band is taut and grouping? Consider that.
masks subluxation, giving a false negative. If the same joint is
tested again in flexion the subluxation will be evident as the caudo- ●● A n acutely traumatised stifle, often with meniscal and/or collateral
lateral is naturally relaxed in flexion. injury does surprisingly well with primary reconstruction and
intracapsular grafting.
But what about a partial partial? Or more accurately, early cruciate
disease. In the majority of dogs, there is a gradual and progressive ●● B ut does a chronically arthritic stifle represent a hostile
loss of cruciate ligament fibre integrity that culminates in a environment to an intracapsular graft? Extra-capsular would
complete tear. In fact, it is accepted that with few exceptions, seemingly be more appropriate.
partial tears will become full tears over time. Cruciate disease
is therefore a continuum and many dogs will present with ●● H eavy and giant breed dogs have a tendency to do less well with
intermittent, progressive lameness without any drawer evident traditional surgeries , but are good candidates for newer, dynamic
as only a proportion of the cranio-medial band has torn at that techniques.

●● C onsider conservative management (rest, physical therapy,
NSAIDs, weight management, graded exercise regimes) for infirm
couch potatoes.

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Extracapsular Cruciate Technique Workshop 5

2. DIAGNOSIS OF
CRUCIATE DISEASE

History taking should include onset, progression, duration, Radiography - two standard views: caudo-cranial and medio-
and response to rest or previously prescribed medication. lateral. Special views: patellar groove flexed/extended, and TPLO/
Consideration of the signalment can improve diagnostic accuracy TTA planning (long limb including hock). Radiographic indicators
by raising suspicion of disease syndromes based on age, breed, or of degeneration of the stifle joint include osteophytosis of the
lifestyle. An orthopaedic examination is performed to localise signs trochlear ridges, fabellae, distal patella, and tibial plateau. Cranial
of lameness to the stifle. displacement of the tibia can be seen in CCLR. Young animals
occasionally present with avulsion fractures. The patella fat pad
Clinical signs defines a space between the joint fluid and the patellar ligament.
It is normally triangular in shape
● L ameness – often acute, even with chronic CCL disease
Effusion is observable on radiographs as the loss of the triangular
● S everity varies from mild to NWB, improves with rest, shape of the fat pad. Effusion can be subtle, therefore it is
exacerbated by exercise important to not overexpose radiographs. Effusion indicates
abnormality - test for drawer in flexion and extension. In the
● P ain on manipulation esp drawer absence of instability, arthrocentesis is indicated to rule out
inflammatory joint disease.
● P eriarticular fibrosis – medial buttress
The tibial plateau angle is measured on radiographs by connecting
● S ynovial fluid effusion – poor definition of the patellar ligament the tibial insertion points of the cruciate ligaments. There is intra-
and inter- observer variation of the magnitude of 3 and 5 degrees
● M uscle atrophy – requires chronicity respectively (Caylor et al JAAHA 2001). Since the advent of the
TPLO, there has been a popular misconception that the TPA in
● I nstability – cranial drawer test, tibial compression test +/- dogs with CCLR is somehow casually associated with the disease.
crepitus No significant differences were found between Labradors with
confirmed CCLR and those old enough to be considered at low risk
Physical examination should evaluate for possible effusion, medial of disease (Reif & Probst Vet Surg 2003). Retrospective analyses of
buttress and patellar stability, ROM, and any clicking/crepitus. skeletons and radiographs in collections (inc Wolf skeletons) has
Comparison of thigh muscle circumference may reveal atrophy. shown no differences between groups with and without cruciate
Manipulative tests include the cranial drawer test and tibial disease - the overall mean was 24.5 degrees (Venzin et al VCOT
compression test. 2004). Rick Read reported CCLR in dogs with pathological TP slope
as the result of growth plate disturbance. Pathological angles have
The tibial compression (thrust) test is valuable for large breed been reported at up to 65 degrees and in these selected cases it
dogs with huge stifles and can elicit drawer in a complete cranial is likely that the slope leads to CCLR. Dogs with lower slopes stand
cruciate ligament rupture (CCLR) even in tense unsedated patients with more extended stifles such that the TPA during weight bearing
and also when standing. is not significantly different to dogs with steeper TPAs (and a more
flexed stifle stance) (Wilke et al JAVMA 2002).
NB - Don’t be fooled by the small amount of laxity (with a distinct
end-point) of the cruciate ligaments in pups. An avulsion of the Should I x-ray all cruciate cases?
CCL is possible due the ligament being stronger than the still
developing bone, but a mid-body tear is very unlikely. If you get I find radiography valuable in the following circumstances:
laxity - check instead for a growth plate injury/tibial crest avulsion.
It is essential to radiograph pups with stifle lameness. ● O lder dogs to rule out concurrent neoplasia

So an easy diagnosis…but there are traps for ● T raumatic cases to diagnose CCL, collateral, or long digital
young players extensor avulsion

● S ince CCLR is often chronic with an acute exacerbation of signs, ● S ubtle cases or partial tears to confirm effusion and early DJD to
it can be mimicked by a second disease in a dog with chronic confirm diagnosis
changes, like a buttress - use stifle pain to guide investigation.
● ? ? Any case to document the degree of DJD prior to surgery
● A nd even if stifle pain is present, there could be two diseases.
Consider radiographing older patients routinely. ● P art of planning for an osteotomy technique

● B ilateral +/- recumbent, can be confused for neurological
conditions.

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Extracapsular Cruciate Technique Workshop 7

3. SURGICAL
MANAGEMENT OF
CRUCIATE DISEASE

It should be made clear to clients that we do not “repair” a ruptured increased rate of surgical infection (up to 21% infection rate). The
CCLR and that we cannot make an unstable joint normal. The use of wire is associated with early fatigue fracture and potential
concept is surgical management rather than cure. intra-articular migration. The most commonly utilised material is
currently mono-filament leader line. The rate of removal is lower
It is appropriate to ask whether surgery is required at all, than with the multi-filaments, but knot slippage, breakage, and
particularly in small dogs and cats where rest and anti- material stretch can lead to early return of laxity. In addition, the
inflammatories, and importantly “time”, will result in a high tibial tunnel can remodel and the fabellar ligament can tear and
proportion of animals (80% or so) never requiring surgery to reach a stretch, with the cranial drawer returning in as little as two to three
good-to-excellent level of function. months. Also, the extracapsular prosthesis is not isometric and
leads to external rotation of the foot due to the lateralisation of the
The veterinarian should consider the dog’s age/size/ tibial crest. Recent improvements in instrumentation (bone anchors
comorbidities/lifestyle when deciding whether to recommend and crimping tools) have seen further refinement of the technique.
surgery over conservative management. Infirm and very geriatric
animals with a sedentary lifestyle would suit a conservative Paatsama originally described an intra-articular procedure passing
approach whereas a young, active large breed dog has a higher a fascial strip through femoral and tibial tunnels in the 1950s.
likelihood of a good outcome with surgery than without. In 1979, Arnoczky and co-workers introduced the “over the top”
procedure, which used a medial third graft patellar tendon graft.
The two primary goals of surgical intervention are to 1) inspect The “over the top” position was later shown to be close to isometric,
and appropriately treat any damaged meniscal cartilage, and then and in a favourable location in comparison to the femoral bone
2) restore stability to the joint against cranial tibial subluxation. tunnel. More recently, Shires and Hulse introduced the “under and
Stabilisation has typically been attempted with static stabilizers over’’ in the 1980s, which uses a lateral third graft passed beneath
such as grafts and prostheses with mixed success. Good to the inter-meniscal ligament, then through the joint in the “over the
excellent clinical outcomes have been reported in 80% of patients top’’ position.
undergoing a variety of surgical techniques. Ongoing degenerative
changes and the return of cranial subluxation is the norm, and The principal disadvantage of the use of an autograft in dogs is
late meniscal injury is a significant cause of poor outcomes and the weakness of the resultant graft. The Arnoczky medial third
re-operation. Recently a new concept of stifle biomechanics has graft is only 10%, and the middle or lateral third grafts are only 29%
led to the concept of dynamic stabilisation. New techniques have as strong as the native CCL. The grafts take five to six months to
been developed that have proven to return a greater proportion of re-vascularise and may stretch, avulse, or tear due to physiologic
patients to athletic function and reduce the progression of DJD. loads. Post-mortem examination has shown variable graft survival
and functionality. Combined techniques utilise intracapsular grafts
A history of treatment of CCL injury/disease in dogs. supported by an extracapsular prosthesis to reduce stress on the
graft as it re-vascularises.
Traditional surgical techniques fall into two major categories: extra-
and intracapsular. Despite these concerns both intra- and extra-articular techniques
are anecdotally associated with good results, with claims of 80 to
The extracapsular procedures include imbrication and retinacular 90% good to excellent function in owner evaluations. And these
prostheses. In 1966, Childers reported results of imbrication of results seem to be largely regardless of the technique used. Many
the medial and lateral aspects of the joint capsule using Lembert authors have suggested that fibrosis of the stifle joint ultimately
sutures to decrease cranial drawer. Retinacular techniques, as stabilises the stifle and that the technique chosen is less important
first described by DeAngelis and Lau in 1970, involve placing one than the decision to perform surgery. But acceptance of peri-
or two large, non-absorbable sutures around the lateral fabellae articular fibrosis as an end-point means accepting loss of range
anchored to the distal patellar ligament. of motion and lesser athletic function. The Holy Grail would be a
technique that halts the progression of further DJD and stabilises
Disadvantages of the extracapsular technique stem from the the stifle without loss or ROM, optimising athletic function….
prosthetic materials and anchorage points. Multi-filament materials
are strong for their size and knot well, but are associated with an Recent “advances” in the surgical management of
CCLR

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Extracapsular Cruciate Technique Workshop 9

3. SURGICAL
MANAGEMENT OF
CRUCIATE DISEASE

The older techniques previously described statically stabilise Stauffer et al JAAHA 2006). As the technique has evolved along
the stifle by countering the cranial drawer with tension of the with improvements in technique, instrumentation and implant
graft/prosthesis. Recent developments in cruciate surgery have design, the complication rate is consistently less than 10%. Once
centred around stabilising the stifle through dynamic means. In the technique is mastered the results are very repeatable and most
1983, Henderson described the tibial compression test. The tibial specialist practices in the US have converted to the TPLO as the
compression test is performed by placing a finger down the line of preferred technique for CCLR in dogs. This has meant a swing from
the patellar ligament to its insertion on the tibial crest, then flexing a general practice procedure to a referral surgery. Is there still a
the hock with the stifle extended. The tibial compression test role for LFS?
mimics the forces that occur during weight bearing. In the absence
of a CCL the tibia subluxates cranially, this is “tibial thrust”. I list infection 3 to 5%, fracture 1%, and late meniscal tearing as the
major complications for my clients to consider when consenting to
In 1983, the late Barclay Slocum first described the importance an osteotomy technique.
of tibial thrust on the biomechanics of the stifle. The tibial wedge
osteotomy (TWO) was introduced in 1984 to study the effect of Pros:
altering tibial plateau angle to neutralise the cranial tibial thrust.
The tibia is proposed to subluxate when the total joint force is As high as 93% owner satisfaction ratings have been reported with
not parallel to the long axis of the tibia. It was found that when TPLO, higher than other techniques (Priddy et al 2003), although in
the tibial plateau slope is reduced to a theoretical 6.5 degrees that study 30% were still receiving some form of anti-inflammatory
in-vitro, cranial tibial thrust does not occur. A recent mathematical medication at follow-up.
modelling method has challenged this assumption claiming that
above 0 degrees the CCL is still loaded. Cons:

In 1993, Slocum introduced the tibial plateau levelling osteotomy In addition to the complications stated above, the TPLO (and TWO
(TPLO) in which a radial osteotomy is performed on the proximal or TTO) involves an osteotomy through the weight bearing axis of
tibia with a specially designed bi-radial saw blade. The tibial the tibia. Should this fail to heal the dog has a broken leg (versus an
plateau is rotated to achieve a post-operative TPA of approx. 5 to 7°, avulsed tibial tuberosity).
and is stabilised with a custom plate.
It is also imperative that the radial cut is made perpendicular
Early reports suggested that a TPLO could prevent further arthritic to the axis of the tibial plateau to avoid the potential for limb
change in the CCL deficient stifle joint, but most studies do malalignment after surgery. Even minor angular compromise at the
show progression of DJD, albeit at a lower rate in comparison to osteotomy site can cause significant deviation of the footfall.
established techniques. Rayward et al (JSAP 2004) reported that
60% of 40 dogs had not increased on osteophyte scoring at six A further effect of the TPLO is the exacerbation of a “pivot shift”, or
months – but 40% had. sudden unopposed internal rotation of the stifle during the stance
phase of the stride. This is more problematic in dogs with tibial
Anecdotally the patients return to soundness more rapidly and bowing or genu varum, and is brought about by the relaxation of
have greater overall athletic function. However a force plate the lateral collateral induced by the tibial plateau rotation.
study conducted in Labradors found little difference between a
lateral fabellar suture and TPLO procedure at two and six months The Tibial Tuberosity Advancement (TTA) was conceived in Europe
(Conzemius et al 2005). Intracapsular performed significantly worse at the time when the TPLO was being introduced in America, but
at two months, but no difference was noted at six months. Using was restricted by a US patent. The TTA was developed by Professor
three techniques including TPLO, only 15% of all operated dogs had Pierre Montavon of the University of Zurich and Slobodan Tepic
returned to 80% normal weight-bearing as measured by force plate of KYON (makers of the Zurich Cementless Hip prosthesis). The
at the six month follow-up. inventors have proposed a new model of the forces that summate
around the stifle. They propose that when the sum of the stifle and
In comparison to static techniques, the TPLO/TWO operation hock extensors, and the ground reaction force is not parallel to the
is technically demanding and there was initial reports of 9 to patellar ligament, then tibial translation occurs. Rather than attempt
24% risk of severe complications including non-union and tibial to change the TPA to alleviate the vector forces that lead to drawer,
fracture, infection, or implant failure (Priddy et al JAVMA 2003, the TTA seeks to normalise the TPA to the patellar tendon.

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Extracapsular Cruciate Technique Workshop 11

3. SURGICAL
MANAGEMENT OF
CRUCIATE DISEASE

Rationale for the TTA: Based on the work of Slocum, Tepic and Montavon the Triple Tibial
Osteotomy (TTO) has been developed by Warrick Bruce (NZ). It
1. T otal joint force in the stifle is approximately parallel to the avoids the need for specialised biradial saw equipment whilst
patellar ligament. following the principles of Slobadan Tepic to ensure the tibial
plateau is perpendicular to the patella ligament to minimise shear
2. If the angle between the patellar ligament and the common- strain at the CrCL. The technique does not require the specialised
tangent at the tibio-femoral point of contact, call it alpha, is 90 blades or saw of a TPLO, or the significant inventory of implants
deg, there is no shear component of the total joint force, and of the TTA. It does require a saw guide and measuring/marking
neither of the cruciates are loaded. gauge and general purpose TTO/TWO/TPLO plates.

3. In the canine stifle, alpha is 90 deg at 110 deg of flexion – call CBLO - Cora based levelling osteotomy introduced by Don Hulse
this the cross-over flexion point; in full extension alpha is approx
105 deg; in full flexion it is approximately 80 degrees. CBLO surgery works in a similar way to a TPLO procedure, however,
the bone cut is angled in the opposite way, which means it is
4. T hus with the stifle in extension with respect to the cross-over further from the joint. CBLO aims to allow the leg to bear weight
point; the load is on the cranial cruciate. With the stifle flexed in a way that is closer to normal after the surgery site has healed.
past the cross-over point in flexion, the load is on the caudal The use of CORA’s comes from angular limb deformity correction
cruciate. (Paley). Radiographic measurements are used to determine the
proximal tibial anatomic axis and distal tibial anatomic axis. The
5. T herefore in a CCL deficient stifle the joint can be stabilised by intersection of these two axes lines is the anatomic CORA. A
shifting the cross-over point to the full extension point. proximal medial tibial approach exposes the metaphysis or the
tibia. Radiographic measurements are transferred to the proximal
An opening vertically directed osteotomy is used to advance tibia. A dome osteotomy centered at the CORA is completed and
the tibial tuberosity a pre-determined distance to normalise the the proximal segment rotated to achieve the desired postoperative
patellar ligament to the tibial plateau angle. TPA (9 to 12 degrees). Stabilization of the osteotomy was achieved
with a bone plate and screws augmented with a headless
The osteotomy is stabilised by a titanium spacer and a tension compression screw.
band plate. The gap is grafted with an autogenous cancellous
graft. Development work in the first 150 procedures over two years, Late meniscal tears
refined the implants. Controlled clinical release in the USA to 50
surgeons occurred in early 2004. By the end of 2004, the system The most common complication associated with all cruciate
had been fully released, and by Feb 2006 some 200 surgeons surgeries is probably the “late meniscal tear”. Also now commonly
had adopted the TTA worldwide with approximately 7000 referred to as a post-liminary tear. When the TPLO was first
procedures performed. offered, a release of the medial meniscus (mid-body incision or
caudal meniscotibial ligament release) was promoted to reduce
Advantages of the technique include decreased surgical time, no the 20% incidence of LMTs that was seen in the first cohort. Its
angular change to the tibial weight-bearing axis, and a smaller use is supported by MRI study that purported to show that MR
wound with less muscle trauma. Subjective outcomes in several allows the meniscus to avoid impingement by the medial condyle.
studies have shown good to excellent results in 83 to 96% of cases. Clinical studies have demonstrated the effectiveness of a MR at
One study showed that Peak Vertical Force improved significantly reducing LMT rates (2.6% incidence of postoperative meniscal tears
following TTA, but only reached 90% of normal controls. In another after meniscal release and a 27% incidence of meniscal tears in
study, subjective owner assessment at least one year after surgery unreleased joints). However, at least one series of 438 cases that
suggested that fewer dogs treated with TTA reached normal were treated by TPLO without meniscal release had a return rate of
function than did dogs treated with TPLO however overall owners only 2%. So if only a small proportion of dogs will benefit from a MR,
felt that 89% of dog had good or excellent results. but all treated dogs will suffer from functional injury to the medial
meniscus as a result of MR, is it justified?
Since the original TTA method was published there have been
various commercial companies offering either identical implants,
similar implants (cuttable cages and plates with screws not forks),
or alternative surgeries under the same biomechanical model
(Modified Marquet Procedure, Ossibility TTA, TTA-Rapid and
Fusion TTA).

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3. SURGICAL
MANAGEMENT OF
CRUCIATE DISEASE

And there has been further conflicting evidence. A comparison of
arthroscopy no meniscal release+TPLO versus open/MR+TPLO
versus open no release+TPLO showed that the rate of late
meniscal injury was lowered by performing a release when
an open approach was made to the joint. But there was little
difference between arthroscopy no release and open/MR. This
does not make intuitive sense, and suggests that the risk of late
meniscal tears may be related to factors other than the release
itself. Overall the low incidence of late meniscal injury in all groups
means that the benefit of MR may not be as clinically relevant as
first thought.

Over time the importance of the meniscus to both normal stifle
biomechanics and meniscal loss on the progression of DJD has led
many surgeons away from routine MR. This has lead to a debate
between TPLO and TTA advocates as to which has the higher risk
of LMT. TTA has developed a reputation of a higher LMT rate, with
reports of 10 to 22% of cases post TTA despite the theoretically
superior joint kinematics and contact mechanics of TTA compared
with TPLO. However recent recommendations to oversize the
cage (perform advancement that is at least one size larger in cage
width than measured from radiographs) has improved results.
Indeed a recent study from the UK (Matchwick, A. I. M., Bridges, J.
P., Scrimgeour, A. B., & Worth, A. J. (2021). A retrospective evaluation
of complications associated with forkless tibial tuberosity
advancement performed in primary care practice. Veterinary
Surgery, 50(1), 121-132. doi:10.1111/vsu.13502 revealed only a 3.2%
late meniscal tears in 374 forkless TTAs which were upsized (over
advanced) by one cage size on average.

There is no proper case matched comparative study of TPLO vs
TTA, but evidence from Peter Bocher (flukin.de) that TPLO more
reliably prevents tibial thrust during natural loading than TTA
means an intact meniscus is likely at more risk following TTA
than TPLO.

My own take on this is that NO technique thus far dynamically
stabilises the stifle AND prevents internal rotation. Adding a LFS
to an osteotomy procedure is now common when the surgeon
assessed internal rotation as excessive. One manufacturer of TPLO
plates has even added an eyelet for the anchor point of a LFS as
the plate is on the medial aspect in the area you would normally
drill to.

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Extracapsular Cruciate Technique Workshop 15

4. EVIDENCE BASED
DECISION MAKING IN
CRUCIATE DISEASE

In human medicine it is accepted that many people with an ACL This paper is largely heralded as the evidence that surgical
injury cope well without reconstruction of the ligament. Knee pain intervention is beneficial to the majority of larger dogs, and less
and immobility are largely determined by meniscal pathology necessary for small dogs to regain function, yet as a retrospective
which can be addressed arthroscopically without stabilisation. case comparison it only provides class IV evidence.
Indeed in many countries reconstruction is only favoured in athletic
and relatively young individuals. For a professional athlete, surgery One systematic review has compared surgical versus conservative
might be the difference in being able to remain competitive, but management (Hinterwimmer et al 2003). Over a 22-year period
is considered a short-term solution. There is little evidence that the authors identified 11 different studies (two randomized, two
reconstruction provides a benefit to patients in the long-term, rates prospective, and seven retrospective studies). In all but one,
of knee replacement are unaffected by surgical intervention to the results of the operative group was always better than the
stabilise the ligament. In fact it appears that the similarities to the conservative group (Innes 2010). Combining the results of the
veterinary debate are telling. two randomized studies showed significant advantages for the
operative treatment of CCLR in dogs.
So what are the fundamental questions for which we need
evidence to base a decision? Q 2. If we accept that surgical intervention to stabilise the stifle is
desirable, which technique is the most efficacious?
Q 1. Does surgical management of CCLR in the dog offer
significant benefits over conservative management? Since the advent of the TPLO and its patenting as a procedure in
the 1990s, there has been controversy over the new paradigm. The
The landmark study we often refer to was by Phil Vasseur from rapid adoption amongst specialists suggests that in clinical use the
Davis, published in 1984. He reported on the clinical results of results are repeatedly superior to procedures previously performed.
non-surgical management for CCLR in 85 dogs that were restricted Controversy remains as to the real difference in long term outcome
to leash walking for three to six weeks, underwent appropriate over traditional techniques. Most surgical conferences in recent
weight reduction, and were prescribed aspirin at 10mg/kg. Dogs times have had sessions on ‘evidence based medicine’ at which
were retrospectively analysed and financial considerations (owners detractors call for randomised, controlled, blinded, prospective
unable to afford surgery) was the main reason for conservative clinical trials at a multi-institutional level, and proponents point to
management. In the same time period over 600 dogs received the techniques wide acceptance. The fact remains that we do not
surgery but were not assessed in the same manner. The details have such studies for any current procedure and traditionalists
are very sketchy, but it appears as though the dogs were re- cannot claim to have the answers here either.
evaluated at six months after diagnosis. If they were completely
sound with minimal or no muscle atrophy and full range of motion There are no RCTs and only two prospective cohort comparisons
(c.f. the other side) they were considered normal. If there was only using objective measures such as force plate (Conzemius et al
occasional lameness, minimal or no muscle atrophy, and normal or 2005, Au et al 2010). In the former, 131 Labradors with unilateral
minimal loss of ROM, they were considered improved. Unchanged CCLR and injury to the medial meniscus were treated with either
or worsening lameness was classified as a failure. Surgery was LFS, intracapsular graft, or TPLO (non-randomised, owner/
apparently performed on all such failures. Owner and veterinarian surgeon preference). There was no difference between TPLO
follow-up was described for the conservative group at two years and LFS however intracapsular grafts had lower ground reaction
post diagnosis. There were 57 dogs weighing more than 15kg forces at two and six months. Compared with clinically normal
(mean 33kg) of which 11 (19.3%) were classified as improved (no labradors, 14.9% of LFS, 15% of IC and 10.9% of TPLO treated dogs
dogs were normal). At the two year follow-up, four dogs were had normal limb function based on force-plate. By defining clinical
described as normal. The remaining 46 (80.7%) were classified as improvement as having force plate data that was closer to the mean
failures. At surgery medial meniscectomy was required in 27 of the of normal dogs c.f. the affected dogs pre-op, only 15% of ICS, 34%
37 dogs. of TPLO and 40% of LSS were considered to be clinically improved
by six months. In the study by Au et al, a cohort of medium to
In contrast, 24 of 28 (85.7%) of dogs less than 15kg were described large breed dogs presenting to the University of llinois were non-
as normal or improved at minimum. All four failures were randomly treated with either TPLO or LFS (owner/referring vet
subsequently operated and all had meniscal injuries at six months preference), and followed with radiographs and force-plate analysis.
follow-up. OA increased as measured radiographically and peak vertical force
improved in both groups, but there was no significant difference
16 Extracapsular Cruciate Technique Workshop between treatment groups.

NOTES

Extracapsular Cruciate Technique Workshop 17

4. EVIDENCE BASED
DECISION MAKING IN
CRUCIATE DISEASE

Two EBM reviews are notable – Evans 2003, and Aragon & Budsberg more invasive techniques, but not clinically a problem for the
2005. One of the principles of EBM is to first define the question you vast majority of patients and rarely requiring intervention. It can
are seeking to answer. For cruciate disease in dogs, Steve Budsberg also be claimed that the actual rate of complications is much
phrased the question “in dogs with cranial cruciate injuries and lower in the hands of experienced specialists doing large
instability (patient or problem), which surgical procedure (intervention numbers of TPLO, versus the smaller studies investigated.
considered) will allow consistent return to normal clinical function Richard Evans and John Innes have more recently calculated
postoperatively (intervention outcome), and is that procedure superior NNT for TTA and found it to be three, (therefore worse than
to other current techniques (comparison population)?” LFS and TPLO both at two) and NHT of seven, the same as
TPLO (Innes 2010).
A search was conducted through VIN, MEDLINE, and CAB ABSTRACTS,
and found greater than 200 journal articles, proceedings and abstracts Since these studies, there has been further prospective
that dealt with cruciate injury, yet fewer than 28 provided relevant data evaluations of TPLO and LFS.
for answering the question above (Aragon & Budsberg 2005). There
were no class I/II studies, five class III, and 23 class IV. Gordon-Evans, Wanda J et al. Comparison of lateral fabellar
suture and tibial plateau leveling osteotomy techniques for
Evidence Classes as used by Aragon and Budsberg 2005 treatment of dogs with cranial cruciate ligament disease.
JAVMA 243(5), 675-680, 2013.
Class I - Evidence derived from multiple, randomized, blinded, placebo-
controlled trials: Objective - To compare one year outcomes after lateral
fabellar suture stabilization (LFS) and tibial plateau leveling
Class II - Evidence derived from high quality clinical trials using osteotomy (TPLO) for the treatment of dogs with cranial
historical controls: Limited to none depending on the strictness of the cruciate ligament disease.
criteria you apply.
Design - Randomized blinded controlled clinical trial.
Class III - Evidence derived from uncontrolled case series:
Animals - 80 dogs with naturally occurring unilateral cranial
Class IV - Evidence derived from expert opinion, and/or extrapolated cruciate ligament disease.
from bench research or physiologic studies:
Procedures - All dogs were randomly assigned to undergo
The author’s stated “in summarizing the evidence available, it is clear that LFS (n = 40) or TPLO (40). Clinical data collected included
no single procedure has enough data that allows any statements about age, weight, body condition score, history information, stifle
potential for long term success in terms of clinical outcome. Furthermore, joint instability, radiographic findings, surgical findings,
given the data available today, it is impossible to favor one procedure and complications. Outcome measures were determined
(TPLO, fibular head transposition, extracapsular suture stabilization, prior to surgery, at six and 12 weeks, and six and 12 months
intracapsular ligament replacement) over another at this time.” after surgery; including values of pressure platform gait
analysis variables, Canine Brief Pain Inventory scores, owner
Richard Evans, a biostatistician, presented an evidence-based review satisfaction ratings, thigh circumference, and stifle joint
of CCLR management at the ACVS 2005 Symposium. He used a goniometry values.
technique from human medicine, number needed to treat to help/
harm. He analysed three outcome papers with objective measures and Results - Signalment and data for possible confounding
four observation studies, looking at complication rates. He calculated variables were similar between groups. Peak vertical force
the number needed to treat to provide a benefit for the patient of affected hind limbs at a walk and trot was 5 to 11% higher
(TPLO NNT two, LFS NNT two) and found that both techniques were for dogs in the TPLO group versus those in the LFS group
equally effective. He calculated the number needed to cause harm (a during the 12 months after surgery. Canine Brief Pain Inventory,
complication) as NNH of seven for TPLO versus 13 for LFS. This means goniometry, and thigh circumference results indicated dogs in
that a complication occurs for every seven TPLO whereas only every both groups improved after surgery, but significant differences
13 for LFS. On face value, a TPLO cannot be recommended over a LFS between groups were not detected. Owner satisfaction ratings
as the benefit does not out-way the greater risk of harm. As the studies at 12 months after surgery were significantly different between
did not mimic each other’s criteria for the definition of a complication, groups; 93% and 75% of owners of dogs in the TPLO and
this analysis still has some short-comings. Additionally, one of the LFS groups indicated a satisfaction score >= 9 (scale, 1 to 10),
complications reported was wound swelling - a characteristic of the respectively.

18 Extracapsular Cruciate Technique Workshop

NOTES

Extracapsular Cruciate Technique Workshop 19

4. EVIDENCE BASED
DECISION MAKING IN
CRUCIATE DISEASE

Conclusions and Clinical Relevance - Kinematic and owner not a straight line). In some cases of revision surgery I have found
satisfaction results indicated dogs that underwent TPLO had better the prosthesis to have migrated into an intra-articular position and
outcomes than those that underwent LFS. destroyed cartilage on the condyle. The latest recommendation
is that a LFS should be placed with anchor points as isometric as
Comparison of Long-Term Outcomes Associated With Three possible, via revised recommendations for the tibial tunnel, see
Surgical Techniques for Treatment of Cranial Cruciate Ligament below. This may reduce pain from joint capsule pressure.
Disease in Dogs. Christopher, Scott A.; Beetem, Jodi; Cook, James
L. Veterinary Surgery 42, 3, 329-334 My current recommendations depend on the patient’s signalment/
comorbidity, form of cruciate disease, and owners expectations.
Objective - To evaluate long-term (>1 year) outcomes with respect
to function and complications in dogs undergoing TightRope For group I (acute ruptures without pre-existing injuries) in lean
(TR), tibial plateau leveling osteotomy (TPLO), or tibial tuberosity working dogs, I find that a combination of an intra-articular graft
advancement (TTA) for treatment of cranial cruciate ligament supported by an extracapsular prosthesis and addressing any
(CCL) disease. collateral and meniscal trauma works well. This offers a cost
advantage for farmers/shepherds that may not feel the extra $$ for
Study Design - Retrospective clinical cohort study. Methods an osteotomy procedure is justified.
Medical records from 2006 to 2009 were searched and cases
included when all data were available and clients returned a For dogs in Group II, the dog’s age and athleticism can make a
completed questionnaire based on their assessment of their dog difference to the owners perception of value for money. For large
at least one year after surgery. Outcomes associated with TPLO, dogs, I generally recommend a TPLO (or a TTA if they have a TPA
TTA, and TR were determined and compared based on medical <27 degrees), or a TTO if there is concurrent medial patella luxation,
records and questionnaires data regarding return to function, medial patella subluxation. A TTO allows lateralisation of the tibial
presence and degree of pain, and complications. tuberosity more easily than the TPLO.

Results - Case meeting inclusion criteria were: TPLO (n=65), If a client cannot afford a tibial osteotomy, or has a preference for an
TR (n=79), and TTA (n=18). TTA was associated with significantly extracapsular, then I will still perform these with the understanding
(P<.03) higher rates of major complications and subsequent that the heavier the dog the more likely they are to fail. I mainly
meniscal tears than TPLO and TR, and TPLO had significantly use appropriately sized leader line, but also offer the iso-toggle
higher rates of major complications and meniscal tears than TR. procedure at Massey as the theatre is top-notch sterility wise.
Percent of function >1 year after surgery was 93.1%+10.0% for TPLO,
92.7%+19.3% for TR, and 89.2%+11.6% for TTA. Significantly (P=0.016) In small breeds 10kg or less, then I recommend waiting four to
more TPLO and TR cases were classified as reaching full function six weeks so see if a conservative approach will provide a good
than TTA. The highest levels, frequency, and severity of pain were outcome. Many small dogs will improve and use the leg very well
noted in TTA cases, however, no significant differences were noted and “cope” with the instability, as meniscal tears are less common
among groups. in smaller dogs at presentation. They may later injure the meniscus,
but this is not common and most that improve within a few
Conclusion - Long-term outcomes for TPLO and TR were superior weeks will make a very good long-term recovery. Those that are
to TTA based on subjective client and DVM assessments. Each doing poorly after a month should have surgery as there is a high
technique was associated with a high long-term success rate with possibility of a painful meniscal tear.
TR showing the highest safety-to-efficacy ratio.
A couch potato, or dog affected by another debilitating disease,
What to make of it all? should be considered a candidate for medical management or
arthroscopic meniscal surgery. In the US it is becoming more
If early weight-bearing is taken into consideration then a dynamic popular to perform arthroscopic meniscal surgery and see if the
stabilisation technique wins hands down, as we all appreciate that dog rehabs well before offering a stabilising procedure.
dogs treated by extracapsular sutures are typically non or poorly
weight bearing for one to two weeks after surgery. I have always
thought this to be the result of the prosthesis digging into the
capsule. Afterall, the prosthesis has to pass from a latero-caudal
point to the cranial anchor point, across the rounded joint (it is

20 Extracapsular Cruciate Technique Workshop

NOTES

Extracapsular Cruciate Technique Workshop 21

4. EVIDENCE BASED
DECISION MAKING IN
CRUCIATE DISEASE

Group III dogs have the most to gain, and in my hands at least, 7. 40+% of dogs will rupture their other CCL,
seem to do poorly with other techniques. They are diagnosed 65% if they have existing OA on x-ray
young, and good athletic function is desirable, so a TPLO seems
the best current option. I base this not on the superiority of the 8. M eniscal release (MR) of otherwise healthy
dynamic techniques, but rather the disappointment I have had meniscus may reduce the incidence of late
with extracapsular prostheses in giant dogs. meniscal tears, but is detrimental to joint health.
I avoid MR unless the owner expressed the feeling
Agility, service, and hunting dogs for whom athleticism and an they could not afford another surgery for a LMT
early return to function is mandatory are probably also better
treated by a tibial osteotomy procedure than other techniques, This last point is the most controversial and opinion is still divided
as long as the owners understand the potential for more serious, amongst specialists. I don’t pretend to have the answer, but some
albeit low incidence, of serious post-operative complications. discussion of the available evidence is appropriate.

But overall I believe that the person doing it (skill, experience,
asepsis, and attention to detail) is more important than
the technique.

When I consult on a CCLR case I cover the following with
the owners:

1. When an animal ruptures a cruciate ligament, the stifle is
affected permanently. I cannot “fix” a cruciate, but I can maybe
help the dog cope with the injury and subsequent OA

2. N o technique can yet restore the joint to normality and OA is
inevitable despite surgery

3. T he goals of surgery are to uncover and treat any existing
meniscal disease and to try to provide stability (statically or
dynamically) to slow down the inevitable spiral of degeneration

4. A ll techniques require careful patient rehabilitation for an
optimal outcome

5. S urgical intervention may not be definitive, 5 to 10% of cases will
require re-surgery

6. R e-surgery may be for short-term complications or late
meniscal injury

22 Extracapsular Cruciate Technique Workshop

NOTES

Extracapsular Cruciate Technique Workshop 23

5. MENISCAL SURGERY

Meniscal tears are reported in 50 to 70% of CCLRs, and dogs The following are my recommendations for effective arthrotomy
later confirmed with meniscal injury were often presented
poorly weight bearing despite rest. Failure to diagnose and treat a. Wear a sterile gown so you can “use ya belly”
these lesions may lead to poorer outcomes – hence my general
recommendation in favour of inspecting the joint. When operated b. Have an assistant scrubbed-in
dogs with poor outcomes are critically evaluated, meniscal pain
is often present, meniscal pathology is commonly found (late c. Have good lighting (sterile handle or head lamp)
meniscal injury or missed at the first arthrotomy), and appropriate
meniscal surgery alleviates the lameness within days of recovery. d. Suction

We know that removing a meniscus experimentally causes DJD, e. Electrocautery
and that removal of half a meniscus is as detrimental as total
meniscectomy by failure of the hoop barrel effect. Remove as little f. A set of gelpies to open the joint side to side
as required – partial, caudal, subtotal meniscectomy. Leaving the
vascular rim allows regeneration of a fibrocartilage replacer, but g. A set of stifle distractors or
this is not functional as a meniscus. Arthroscopic inspection can
allow a less invasive means of joint assessment. Since roughly h. A thrust lever or Hohmann retractor
half of all patients don’t have a full blown meniscal tear at the
time of surgery, arthroscopic confirmation of normality prevents i. A Senn-Miller retractor
unnecessary arthrotomy. Advanced training can allow meniscal
surgery to be performed arthroscopically. j. A meniscal probe

In humans, injury of the meniscus is reported with an intact k. A beever handle and blades, meniscal knives/hooks
cruciate ligament following internal rotation. Isolated meniscal
injury is rare in the dog, but has been reported to affect the lateral For medial arthrotomy the dog is positioned in dorsal recumbency.
meniscus in Boxers. The meniscus itself lacks innervation, but
the joint capsule to which it attaches is capable of sensing pain. 1. Have the chest of the dog in a cradle, and the dog down the end
In man, meniscal injuries are not uniformly painful, but when the of the table so the surgeon can stand at the end of the table and
femoral condyle pinches the tear and tugs on the joint capsule, not have to lean in.
acute pain is experienced. Similarly not all tears in dogs are likely
to be painful, but failing to identify and treat a painful meniscal 2. T he leg is hung from a stand and given a final sterile prep
lesion will lead to a less than optimal outcome. Therefore it is best in theatre.
practice to perform an arthrotomy to inspect the menisci, and the
gold standard is to perform arthroscopy. Arthroscopy has higher 3. T he surgeon free drapes the leg with four quarter drapes then a
sensitivity (detection rate) than arthrotomy. foot drape. A final fenestrated barrier drape is applied over the
leg. An adhesive drape (with or without stockinette) is then placed
The lateral para-patellar approach to the stifle makes identification over the skin. If this retracts from the skin edge, a skin stapler is
of the fabella and placement of the prosthesis easier, but the used to tack the edge to the wound after the skin incision.
lateral arthrotomy makes meniscal inspection and particularly
meniscal surgery more difficult. This effect is exacerbated by 4. T he skin incision can be lateral or medial; the latter decreases
chronicity and in partial ruptures, both of which hamper distraction the visible scar but will need to be longer to allow the skin to be
and visualisation. Positioning the dog in dorsal recumbency allows retracted far enough for the lateral fascial incision.
for a medial mini-parapatellar arthrotomy than a lateral approach
through the fascia lata (but remaining extra-articular) for placement 5. T he subcutaneous tissues are sharply dissected in the line of
of the prosthesis. The latter is more awkward but with assistance the intended medial parapatellar arthrotomy. The incision is 5 to
from the theatre team the dog can be repositioned in more of a 10mm from the medial edge of the patella ligament and curves
lateral position after the arthrotomy is closed. proximally between the Sartorius muscle bellies. Care has to be
taken to avoid injuring the medial meniscus distally.
24 Extracapsular Cruciate Technique Workshop
6. I f a lateral arthrotomy is performed the fascia lata incision is 5 to
10mm from the lateral edge of the patella ligament and curves
only gently proximally to avoid the biceps muscle belly. The long
digital extensor tendon must be avoided.

7. The cranial cruciate ligaments are inspected and torn, or
redundant ligament is debrided. I find a combination of sharp
dissection with a #11 scalpel and biting/tearing using sharp
rongeurs works well. Removal of the torn CCL reduces a source
of injured collagen, which would stimulate up-regulation of
collagenases in the joint. I leave partial CCL tears where the
remnant is grossly healthy and tight when probed. Others debride
all partials to completely remove all CCL tissue.

NOTES

Extracapsular Cruciate Technique Workshop 25

5. MENISCAL SURGERY

8. A Gelpi retractor is placed across the arthrotomy to open the
joint. A stifle distractor is placed to open the joint space. A Senn
retractor is placed on the fat pad at the bottom of the arthrotomy.
Alternatively a thrust lever is used.

9. A n assistant steadies the leg and alters the flexion/extension
angle as needed, whilst also placing tension on the
Senn retractor.

10. T he joint is flushed with saline then suctioned. A meniscal
probe is slid under the medial meniscus and gently drawn
forward to detect tears. The upper surface is also checked.
If there is a gentle waviness to the caudal pole axial edge (the
oyster flounce) the meniscus is probably normal. If there is
doubt, remove the stifle distractor and try a Hohman retractor,
and flex and extend the joint to see if there is a caudally
displaced bucket handle tear.

11. B ucket handle tears are treated by cutting the caudal and
medial connections to the rest of the meniscus using a beaver
#25 blade or a #11. Always check for a second tear. A beaked
tear is grasped and the base severed. A caudal avulsion is
pulled forward and the meniscus sectioned to remove the
caudal pole.

12. T he lateral meniscus is also inspected. Remember there should
be greater mobility and a lateral menisco-femoral ligament.

13. The joint is flushed with saline and the joint capsule is closed
with 3/0 monocryl. The fascia is closed with PDS.

Stifle Arthroscopy

In human orthopaedics, knee pain is investigated with MRI.
Meniscal pathology can be accurately detected and characterised
prior to surgery. Whilst MRI has been shown to be diagnostic in
dogs with meniscal pathology, however it’s high cost precludes
widespread use. Arthroscopic investigation is now the gold
standard in veterinary medicine as well as humans. However,
the stifle joint is smaller in dogs than in people and there is a
considerable learning curve.
Stifle arthroscopy has the potential advantage over an arthrotomy
by reducing the size of the incisions and therefore limiting scarring
which can lead to a loss of range of motion. Adhesion between
the overlying fascial planes and the joint capsule impedes gliding
function. Arthroscopy can be performed through an instrument and
camera portal, usually with a separate egress port. In cases without
meniscal pathology (30 to 50%), arthroscopic inspection allows the
joint to be preserved without an unnecessary arthrotomy.

26 Extracapsular Cruciate Technique Workshop

NOTES

Extracapsular Cruciate Technique Workshop 27

5. MENISCAL SURGERY

In cases with a meniscal tear, surgeons skilled in arthroscopy can
perform meniscal surgery, though in some dogs conversion to a
mini-arthrotomy is still required. The patella fat pad can impede
arthroscopic diagnosis, so the use of a shaver to cut a viewing
window is recommended. The view afforded by arthroscopy is
superior to an open arthrotomy due to the high magnification
and fluid environment, with good lighting. The torn component is
grasped or levered forward with a meniscal probe then severed at
its remaining connections.
At the MUVTH we have been scoping a proportion of dogs with
cruciate rupture, particularly those suspected to only have partial
tears. I recently spent time at Gulf Coast Veterinary Specialists in
Houston Texas. Brian Beale and Wayne Whitney (who wrote the
textbook on arthroscopy) were incredible hosts and I learnt many
techniques that I am now putting into practice here at the VTH.
Stifle arthroscopy is more difficult than the elbow or even the
shoulder. Compared to the human knee, there is relatively less
working room and the fat pat impedes visualisation. Shaving
the far pad with an arthoburr handpiece provides a window for
observation, but adds significantly to the cost of the set-up. The
system at Massey uses a single use tip that adds over $250 to the
procedure, in addition to the irrigation tubing and equipment fee
to cover depreciation and wear. The net result is that arthroscopic
surgery can add over $600 to the cost of a TPLO/TTA. The big
advantage is that dogs without meniscal tears can be inspected
through a scope portal and the meniscus probed through a medial
portal, with relatively less injury to the joint (and therefore loss of
ROM) than an arthrotomy. With experience, arthroscopy is as rapid
as an arthrotomy with greater visualisation and less likelihood of
missing meniscal tears. It is particularly beneficial in arthritic stifles
with periarticular fibrosis that can limit visualisation through an
arthrotomy. For extreme cases with abundant buttress, the joint
may need to be opened up then the scope employed through a
traditional lateral portal with instruments through the arthrotomy –
so called scope-assisted arthrotomy.

28 Extracapsular Cruciate Technique Workshop

NOTES

Extracapsular Cruciate Technique Workshop 29

6. TRAUMATIC
STIFLE INJURY IN
WORKING DOGS

The stifle joint is commonly injured in working dogs. In NZ, the
most common mechanism of injury is when a dog attempts to
jump an 8-wire fence and puts a hind-foot between the top two
wires and is caught, hanging on the other side. In many cases,
not only the cranial, but also the caudal cruciate ligament can be
disrupted, along with simultaneous injury to one meniscus and
collateral ligament - most commonly the medial. These cases are
very unstable and termed “stifle disruptions” or luxations rather
than simple crucial ligament tears. Other mechanisms of injury
include forceful hyperextension and violent internal rotation.
Stifle disruptions should be treated by primary repair of the
individual components. The joint should be approached through
the side affected by the collateral tear. The tear will allow the
maximum exposure of the joint, and the joint capsule will be torn
open or can be opened to allow inspection of the menisci. If the
entire meniscus is avulsed from the joint capsule it can be sutured
back into position. If there is significant tearing then the effects
section should be removed. The collateral ligament should be
primarily re-apposed with fine nylon sutures then supported by
a prosthesis placed around bone anchors in the distal femur and
proximal tibia (or fibula head bone tunnel). The choice of “repair” for
the cruciate ligament injury is controversial. Anecdotal evidence of
a large number of private practitioners in NZ suggests that “static”
stabilisation of the stifle with either (or a combination of) intra- and
extra-articular techniques provide excellent outcomes for working
dogs. The caudal cruciate tear is seldom stabilised. Tightening the
joint capsule and embricating the overlying fascia during closure is
often all that is required. Alternatively, a prosthesis from the patella
ligament to the caudal aspect of the tibia or fibula can be added.
The advent of the tibial osteotomy procedures has changed the
way we manage cruciate ligament injury in pet animals, but at least
in NZ, these more expensive techniques have not been widely
adopted in far animal practice. This paper will look at the evidence
behind the new paradigm of dynamic stabilisation.

30 Extracapsular Cruciate Technique Workshop

NOTES

Extracapsular Cruciate Technique Workshop 31

7. CRUCIATE
DISEASE IN CATS

The majority of cats that present with CCLR will have traumatic
tears. It is vital to examine them for the integrity of the collaterals
as a global stifle injury is more common in cats than dogs. Physical
examination will demonstrate drawer as in dogs, and radiographs
will confirm effusion, with or without avulsion fragments off the
tibial insertion point. If patella pole and tibial osteophytes are
present radiographically, then a more degenerative process is
suspected and indeed older and obese cats seem more prone
to CCLR, suggesting some chronic degenerative process can
play a role as in dogs. The incidence of meniscal tears, which do
occur, has not been reported in a large enough cohort for
meaningful data.
Good results have been reported with both conservative and
surgical management, but no direct comparison has been made
between strategies. In one study all 16 cats had visibly normal gaits
five weeks after extracapsular stabilisation, and in another a more
rapid return to function was seen compared to conservatively cats.
But the data is sparse and decisions are made by surgeons based
on their own preference rather than evidence.
In cats with isolated CCLR (no concurrent collateral instability), I
favour an initial conservative approach with cage rest during the
day and access inside for limited periods. If limb use is judged to
be poor after this period, then surgery is recommended just like
in small dogs. If there is multi-ligamentous injury then surgery is
recommended to reconstruct the collateral tear (+ prosthesis) and
stabilise with a LFS. In extremely unstable and large patients a
trans-articular ESF may be needed but adds significant risk
of complications.

32 Extracapsular Cruciate Technique Workshop

NOTES

Extracapsular Cruciate Technique Workshop 33

8. EXTRACAPSULAR
PROSTHESIS FOR CCLR
– TECHNIQUE

First do no harm – tips to minimize infections 18. A drill or a pin placed in a Jacobs chuck is used to drill a tunnel
either caudal to or just in front of the long digital extensor
●● A ppropriate free limb draping, joint surgery should not be tendon. The prosthesis is placed lateral to medial through the
performed through a single fenestrated drape tunnel. Leader line passage can be aided by passing a 14 to 18G
needle through the tunnel.
●● U se adhesive wraps or stockinette sutured/clipped to the
skin edges 19. A second bone tunnel is drilled to allow the prosthesis
to be passed back medial to lateral. It is important then the
●● C onsider an additional drape at the time of inserting prostheses tunnels diverge medially to incorporate a good section of bone
to prevent pull-out. An alternative is to place the prosthesis
●● P rophylactic antibiotics if using implants; cephazolin 22mg/kg, IV through a titanium button and then back through the original
at induction tunnel. I no longer favour the passage of the leader line either
over or under the patella ligament as there is too great a
The following are my recommendations for effective arthrotomy: tendency for the LFS to dig into the joint capsule.

a. Have an assistant scrubbed-in 20. T he two ends of the leader line are placed through a crimp.
A second and third crimp are added to each single strand and
b. Have good lighting (sterile handle or head lamp) the tensioner device is offered up to the prosthesis. The second
and third crimps are crimped close to the tensioner. The
c. Suction tensioner is spread to shorten the prosthesis, and the cranial
drawer tested at a walking angle and in flexion to ensure the
d. Electrocautery prosthesis is neither too tight or too loose. A crimping device is
then used to complete the prosthesis.
e. A set of gelpies to open the joint side to side
21. T he fascia lata is then closed with an embrication pattern.
f. A set of stifle distractors or I prefer a mayo mattress followed by an oversewn edge.

g. A thrust lever or Hohmann retractor 22. T he remainder of the closure is routine.

h. A Senn-Miller retractor Tensioning the LFS can be performed by creating small loops after
passing each end through the crimp then using a gelpi or stifle
i. A meniscal probe distractor to apply a distraction. One click at a time, check there is
drawer and degree of flexion still possible, retighten as necessary.
If you are already familiar with the placement of a LFS A small amount of drawer is preferable to overtightening the
extracapsular prosthesis then the major recent developments prosthesis and have it tear out of an anchor point.
have been:

1. An appreciation of the need for (more) isometric points to locate
the prosthesis

2. T he above includes NOT passing the prosthesis over or under
the patella ligament, instead it is recommended to drill two
tunnels and pass the prosthesis through and back, OR use a
button medially.

Continuing on from the steps in the meniscal section.

14. The fascia lata is incised from above the fabella to the palpable
tuber (Gerdi’s tuber in humans) that forms the caudal edge of
the long digital extensor tendon fossa.

15. A fabella is exposed by placing a Hohmann caudal to the fabella
thereby retracting the biceps femoris.

16. T he fabella is palpated and a cruciate needle is inserted
between the fabella and femur, and forced through with a heavy
needle holder or pair of pliers. The intention is for the prosthesis
to become anchored beneath the femero-fabella ligament.

17. I f the needle does not have swaged leader line, a section of
sterile leader line is placed in the needle and drawn through.

34 Extracapsular Cruciate Technique Workshop

NOTES

Extracapsular Cruciate Technique Workshop 35

8. EXTRACAPSULAR
PROSTHESIS FOR CCLR
– TECHNIQUE

Self-locking loop suture pattern for leader line when not using
crimps. Harder to adjust the tension and just like all knots there will
be some “creep”, and so can be tightened slightly tighter than a
crimp prosthesis.

Figure 1: Tying the self-locking knot. (a) The fabellar loop of Modified Mayo Mattress suture pattern for imbrication to the lateral
material is reflected distocranially and the end of the tibial fascia lata.
tuberosity material are passed through the loop from lateral to
medial. Proximocaudal traction on the two ends reduces the size Follow by oversewing the edge in a simple continuous.
of the loop. (b) The direction of the traction is reversed towards
the tibial tuberosity (distocranially) to tighten the fabellotibial
sutue. The proximocaudal and distocranial manoeuvres may
be repeated to reduce the size of the loop. (c) The first throw
of a square knot is placed lateral to the two strands of material
passing through loop. If necessary, tension on the suture is
increased by applying distocranial traction and simultaneously
tightening the first throw. When the fabellotibial suture is
tightened sufficiently four additional square throws are applied
to the knot.

36 Extracapsular Cruciate Technique Workshop

NOTES

Extracapsular Cruciate Technique Workshop 37

9. CAN A LFS
PROSTHESIS EVER BE
ISOMETRIC? NO, BUT…

Don Hulse established that there was minimal change in distance
between two points; defined as: close to the distal pole of the
lateral fabella and the caudal border of the extensor fossa on the
lateral aspect of the proximal tibia.
Simon Rowe found that the femoral point was critical and was
defined as: the very caudal edge of the lateral femoral condyle
adjacent to the distal border pole of the lateral fabella. The
tibial point was less critical as long as it was placed proximally.
These findings were incorporated in an extra-articular technique
developed by James Cook, when a braided woven poly-ethylene/
polyester tape was placed through bone tunnels and secured on
the medial aspect of the femur and tibia (TightRope© technique).
Isometry of potential suture attachment sites for the cranial
cruciate ligament deficient canine stifle S. C. Roe, J. Kue, J.
Gemma. Vet Comp Orthop Traumatol 2008; 21: 215–220

Summary

For a suture that spans a joint to provide support without limiting
range of motion, its attachment points on either side of the joint
must remain the same distance from each other from full extension
to full flexion. The effect of location of the tibial crest attachment
for a fabello-tibial crest suture was studied in seven canine
cadaveric stifles. The distance from a fabella marker to each of 11
tibial markers was determined from radiographs of each limb, as
it progressed from 150° to 130°, 105°, 90°, 65°, and 45° of flexion.
The marker locations that were more proximal and cranial on the
tibial crest had the least percent change in distance. The effect of
anchoring the suture to the femur at a site other than the fabella
was investigated using the same radiographs. Five marks were
placed in a grid on the caudal portion of the femoral condyle and
supracondylar region. The mean percent change in length from
each femoral point to the five more proximal and cranial tibial
markers was determined. The least change in length occurred
for those femoral points located close to the origin of the cranial
cruciate ligament. Locations more proximal or cranial resulted in
large changes in length, particularly when matched with less ideal
tibial locations. Although this study does not directly examine
length changes in sutures, it demonstrates that there
are some locations for the origin and insertion of an extracapsular
suture that are associated with less length change than others, and
also forms the basis for future investigations.

38 Extracapsular Cruciate Technique Workshop

NOTES

Extracapsular Cruciate Technique Workshop 39

10. ISO-TOGGLE
VETERINARY
INSTRUMENTATION

The iso-toggle technique was developed utilising the principles Identification and retraction of the long digital extensor
of isometric suture placement and using a loop of a new braided, tendon is optional.
spun, ultra-high molecular weight, polyethylene suture called
LigaFiba, secured over a nylon toggle and a tie-down button. An appropriate sized drill bit with drill guide, is positioned over the
LigaFiba is very strong (2.5x the strength of equivalent nylon), has isometric point and a tunnel drilled across the tibia in an oblique
very good abrasion characteristics and is flexible. direction to emerge on the medial aspect of the tibia close to the
distal end of the medial collateral ligament.
Materials: LigaFiba is supplied sterile in three sizes (150, 250, and
500lb), individually double wrapped in a see-through packet. The lateral aspect of the femoral tunnel is then located and the
In each pack there is a straight threading needle with a nylon threading needle passed in a lateral to medial direction to emerge
loop, plus a nylon toggle and a nylon tie-down button. The only under the medial gluteal muscle in the space cleared tunnel and
additional special items of equipment needed are anti-skid drills once it emerges medially the nylon loop of the passing needle
bits (2.0, 2.5, and 3.5mm) and appropriate drill guides. is cut.

Size guide: The nylon toggle is inserted into the loop of the prosthesis, and
while held in this position the prosthesis and the toggle are pulled
150lb (0.6mm) Dogs up to 15kg firmly and carefully down against the bone on the medial aspect of
the femur, ensuring that there is the minimal amount of soft tissue
250lb (1.0mm) Dogs up to 30kg between the toggle and the bone.

500lb (1.6mm) Dogs over 30kg (very thick and bulky) The tunnel is flushed with saline and the edges of the holes rounded
off with a countersink. The soft tissues around the drill hole on the
The femoral isometric point is identified on the caudal edge of the medial side of the tibia are cleared away to allow the nylon tie-down
femoral condyle adjacent to the distal pole of the lateral fabella. button to sit against the bone. The appropriate sized prosthesis
The appropriate sized anti-skid drill is then used to drill the femoral is then removed from the sterile packet. Care should be taken to
tunnel: [150lb LigaFiba 2mm drill, 250lb LigaFiba 2.5mm drill, identify the nylon toggle which is loose, although packed against
500lb LigaFiba 3.5mm drill]. the tied down button. Setting the toggle aside, the threading needle
is then used to start the process of inserting the LigaFiba prosthesis.
The initial direction of the drill hole is at right angles to the bone,
to reduce the chances of the drill bit slipping off the back edge As the objective is to secure the prosthesis against the medial
of the femoral condyle. The use of a drill guide and the anti-skid aspect of the tibia, the threading process starts at this point. The
drill bit goes a long way to preventing this occurrence. Once the needle will emerge on the lateral aspect of the tibia and the
drill bit has entered the bone, the drill can then be redirected to prosthesis is carefully pulled through the tunnel till the tie down
create a bone tunnel that is directed from a caudo-lateral position button, which has already been threaded on to the prosthesis,
to emerge more proximally on the medial side of the femur just comes to gently rest against the medial aspect of the tibia.
under the caudal edge of the medial gluteal muscle belly. Use of
cannulated drill bits which are driven over a pre-inserted guide wire The prosthesis is then progressively tightened, working back from
will eliminate drilling errors. Drilling is not started until the guide the medial aspect of the femur to the lateral side of the stifle, and
wire is in the correct position. then finally to the medial aspect of the tibia. The button is brought
up against the medial aspect of the tibia and temporarily tightened
The tunnel is then flushed with sterile saline and edges of the while the joint is placed through a full range of motion and the
holes should be rounded off using a countersink. The soft tissues stability checked. A slight amount of draw is to be anticipated, but
on the medial side of the femur around the drill hole are cleared there should be no restriction to joint movement. Once the surgeon
away for a short distance to accommodate the nylon toggle. Next, is satisfied with stability of the joint, the LigaFiba prosthesis is then
the isometric point on the lateral aspect of the tibia is identified. secured over the tied down button with multiple throws and the
This is achieved initially by palpation of the extensor fossa, which excess material cut using the special scissors (LFS140TC). The
is defined by prominent cranial and caudal processes or tubercles. button should be positioned against the flat surface of the medial
The tendon of the long digital extensor muscle runs through the aspect of the tibia and then the fascia can be closed over the top
fossa. There are some options here. Hulse defines the caudal with interrupted sutures of an absorbable monofilament suture.
process as the optimum position. Rowe selected the cranial
process, and Cook placed the mark within the fossa close to the
cranial process.

40 Extracapsular Cruciate Technique Workshop

NOTES

Extracapsular Cruciate Technique Workshop 41

11. TIGHTROPETM
BY ARTHREX

The TightRope implant’s FiberWire® suture is constructed of a The 4.75mm and the 5.5mm SwiveLocks are loaded with 2mm
multi-strand, long-chain, ultra-high molecular weight polyethylene FiberTape and used for dogs weighing 20kg and 40kg; the 3.5-
(UHMWPE) core, with a braided polyester and UHMWPE jacket mm SwiveLock is commonly loaded with #5 FiberWire or 2mm
that is used extensively in human surgery for many orthopedic FiberTape, and used for dogs/cats 8kg to 20kg. The femoral site is
applications and provides excellent strength, a soft feel, and located at the level of the distal pole of the lateral fabella. Make a
abrasion resistance. The UHMWPE material has properties that vertical incision through the capsular tissue to expose the joint line
make it stronger and less prone to failure than any other suture between the lateral fabella and caudal margin of the lateral femoral
material. The implant uses bone-to-bone fixation, with superior condyle. The proper position is 3 to 4mm distal to the lateral fabella-
strength and stiffness designed specifically for ligament repair. femoral joint line, as far caudal as possible in the lateral femoral
condyle without engaging articular cartilage. The 4.1mm spade tip
Applications include: drill bit is used to drill the femoral tunnel to the appropriate depth
in the femoral condyle. The femoral tunnel is tapped with the hand
● C oxofemoral luxation stabilization, Tarsus stabilization, CCLR tap to cut threads in the bone that will accommodate the anchor
and FiberTape (note there is no hand tap for the 3.5mm SwiveLock).
Implant Assembly: Palpate and locate the protuberance caudal to the extensor groove;
this is the site for placement of the tibial tunnel. At the caudal
● C onsists of 2 buttons and 2 suture strands of FiberWire or protuberance, beginning as proximal as is possible on the tibial
FiberTape® suture plateau without entering the joint, insert a 0.045 K-wire from lateral
to medial. The K-wire is directed to glide caudal to the extensor
● T he TightRope implant and Mini TightRope implant include an groove to exit at the medial cortex of the proximal tibia. With the
attached passing needle K-wire in position, place a 2mm cannulated drill bit over the wire
and drill a tunnel to exit at the medial cortex. Leave the drill bit in
It uses the femoral landmarks of the isotoggle above - just distal place and remove the K-wire. Through the cannulated hole in the
to fabella, on lateral side of condyle and directed craniomedially. A drill bit, place a nytinol Arthrex suture passer such that the loop.
K-wire, then cannulated drill bit creates the tunnel then the needle
and nylon loop pulls the prosthesis through the femur from medial Note: The nytinol suture aid is placed in the tibial tunnel such that
to lateral. The second hole is drilled from just caudal to, or inside, the loop is positioned medial. The FiberTape is passed through
the long digital extensor fossa using the K-wire and cannulated drill the 2mm button and then loaded into the suture passer to be
bit, to emerge on the medial side below the stifle. The needle is pulled through the tibial tunnel from medial to lateral. Once the
passed lateral to medial, drawing the prosthesis through including free ends of the FiberTape exit laterally, they are loaded into the
the toggle. The nylon is cut off then the prosthesis pulled from the eye of the SwiveLock anchor. Next, the eye of the SwiveLock
proximal medial button to tension and knot, ensuring the toggle anchor and FiberTape suture are placed into the femoral tunnel
lies flat against the medial tibia. (2 to 3mm deep). Eliminate excessive craniocaudal laxity leaving
2 to 3mm normal laxity by tensioning each limb of the FiberTape
Arthrex has since introduced a different anchor system called separately. When satisfactory stability is achieved, the limbs of
SwiveLock. The SwiveLock anchor is offered for CCLs and soft the FiberTape are aligned adjacent to and parallel to the shaft of
tissue-to-bone reattachment. Made with an inert, radiolucent, the SwiveLock. A mark is made on the FiberTape where the limbs
and non-absorbable, thermosplastic material called PEEK, this of the FiberTape intersect the distal end of the anchor. The eye
anchoring system allows for knotted or knotless reconstructions. of the SwiveLock is retracted from the tunnel and the FiberTape
Common sizes include 3.5mm, 4.75mm, and 5.5mm sizes. pulled back through the eye so that the mark is located within the
Specifically designed vents in the anchor body promote bone eye of the SwiveLock. The eye is now re-inserted into the tunnel in
marrow flow and allow for bony ingrowth. preparation for advancement and elimination of cranial laxity. Note
at this point there is "slack" in the FiberTape; this will be eliminated
Isometric Knotless SwiveLock Stabilization: Knotless SwiveLock and the FiberTape will have the tension developed in each arm as
Anchor World Small Animal Veterinary Association World Congress determined above once the eye is seated into the femoral tunnel.
Proceedings, 2013 Don Hulse, DVM, DACVS, ECVS

This system is recommended for use in dogs greater than 10kg.
Available sizes are the 3.5mm, 4.75mm, and 5.5mm SwiveLocks.

42 Extracapsular Cruciate Technique Workshop

NOTES

Extracapsular Cruciate Technique Workshop 43

11. TIGHTROPETM
BY ARTHREX

To seat the eye, a mallet used to drive the eye to the depth of the Marsolais GS, Dvorak G, Conzemius MG. Effects of postoperative
femoral tunnel. The Swivelock is advanced such that the bottom of rehabilitation on limb function after cranial cruciate ligament repair
SwiveLock PEEK anchor is flush with the bone. The square flange in dogs. Journal of the American Veterinary Medical Association
on the shaft is held and the teardrop knob turned clockwise to 220, 1325-1330, 2002
engage the anchor. The anchor is advanced into the femoral tunnel
until the top of the anchor is flush with the bone surface. The strand Priddy et al. Complications with and owner assessment of the
of Fiberwire used to hold the eye in place is unwrapped from the outcome of TPLO for CCLR in dogs: 193 cases (1997-2001). Journal
teardrop knob and the SwiveLock insertion handle is removed. of the Veterinary Medical Association 222, 1726-32, 2003
One arm of the Fiberwire (used to hold the eye) is pulled to remove
the Fiberwire and the Fiberwire suture discarded. The FiberTape is Stauffer KD, Tuttle TA, Elkins AD et al. Complications associated
now cut flush to the bone as it exits the PEEK anchor. Tissues are with 696 TPLOs (2001-03). Journal of the American Animal Hospital
lavaged and the caudal arthrotomy sutured with non-absorbable Association 42, 44-50, 2006’
suture. The fascia lata is advanced and sutured to the patella
tendon. The remaining soft tissue closure is performed as the Steinberg EJ, Brown DC: Tibial Tuberosity Advancement for
surgeon prefers. Treatment of CrCL Injury: Complications and Owner Satisfaction. J
Am Anim Hosp Assoc; 47: 250. 2011
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Extracapsular Cruciate Technique Workshop 45



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