In canine cranial cruciate ligament disease, are conservative treatment and lateral fabellotibial suture recoveries comparable?

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Appraisal, application and reflection

Cranial cruciate ligament (CCL) disease is a leading cause of hindlimb lameness in adult dogs (Ness et al., 1996). Surgical management of CCL rupture (CCLR) is often recommended with a variety of surgical techniques described. Surgical techniques to address CCLR in dogs can be broadly classified into three categories. One category of techniques aims to provide dynamic stabilisation of the CCL deficient stifle by eliminating cranial tibial thrust (CTT). Another category of techniques aims to provide a temporary static fixation by extracapsular stabilisation. The third category of techniques aims to provide a static fixation by replacement of the failed CCL with an intra-articular graft. Evidence based assumptions are difficult to make regarding the preferred surgical treatment option for patients. However most recent reviews appear to support the tibial plateau levelling osteotomy (TPLO) technique (Tikekar et al., 2022; Krotscheck et al., 2016; and Bergh et al., 2014).

The TPLO procedure can be considered an advanced procedure with a significant learning curve and the necessity for additional equipment and expense. Extracapsular suture (ECS) techniques such as the lateral fabellotibial suture (LFTS) technique can often be performed with less expensive surgical equipment and implants, and less overall cost to owners. This makes the ECS a viable option for many patients. The goals of surgery to manage CCLR are to provide immediate stifle stability, allow a quick return to optimal function and slow the development and progression of osteoarthritis in the affected joint.

A 1984 study by Vasseur demonstrated that small dogs weighing less than 15 kg can do well without surgery. The same study showed that outcomes after conservative treatment were poor for dogs weighing more than 15 kg. Considering this, it remains unclear what the expected outcomes would be in a heterogeneous population of dogs.

Clients often opt out of surgery for various reasons including, but not limited to, financial constraints, increased surgical and or anaesthetic risks due to age, and / or presence of other medical, orthopaedic and / or neurologic disease. In these cases, clients might seek to gain more insight into the expected outcomes associated with conservative treatment compared to surgical intervention with ECS in order to decide whether surgical intervention would be worth the accompanying expense and / or risk.

The 1996 prospective experimental study by Jevens et al. compared functional outcomes between modified retinacular imbrication technique (MRIT) and conservatively treated dogs with experimentally induced rupture of the CCL. They demonstrated that dogs that underwent MRIT did significantly better than dogs that received conservative treatment according to the results of force plate analysis, although the recovery was prolonged. However, MRIT and LFTS are distinct procedures. The former was first described by Flo in 1975 while the latter appears to be a hybrid of the lateral retinacular imbrication technique first described by De Angelis & Lau in 1970, the MRIT as described by Flo (1975), and the lateral suture technique as first described by Gambardella et al. in 1981. Both the MRIT and LFTS fall under the extracapsular technique classification. The study by Jevens et al. (1996) therefore, may not be relevant to the clinical question.

A 1996 retrospective study by Chauvet et al. demonstrated that there was no statistical difference in outcomes for dogs treated for CCL disease, between conservatively and LFTS treated stifles according to investigator evaluation. Although owner evaluation demonstrated that LFTS had higher functional scores than conservative treatment, the difference was not statistically significant. Owner evaluation is subjective and difficult to use as a basis for scientific conclusions. The results of owner evaluation could be attributable to the placebo effect in the surgically treated group as the owners were not blinded as to which treatment their dog had received.

The only objective method of outcome analysis in this study was force plate analysis, which showed no statistical difference between the two interventions. The comparison of force plate evaluation of the test limb with the contralateral limb is validated (O’Connor et al., 1989). However, there is no evidence that the contralateral limbs were evaluated before the interventions to ensure that they were normal and therefore, acceptable as bases for comparison.

The study also excluded dogs weighing less than 22.7 kg, making it difficult to determine whether the results can be applied to dogs weighing less than 22.7 kg. The recent availability of client based validated metrology instruments such as the Bologna Healing Stifle Injury Index (BHSII [Pinna et al., 2019]), Canine Orthopaedic Index (COI [Brown, 2014a; 2014b; and 2014c]) and the Liverpool Osteoarthritis in Dogs (LOAD [Walton et al., 2013]), can help address the limitation of lack of objectivity in owner evaluation. However, they would be more relevant if used in prospective, randomised and blinded studies. The paucity of such studies renders these instruments less useful. The significance of this when applying the evidence to a heterogenous population of dogs is difficult to determine.

Owner compliance in the study by Chauvet et al. (1996) was also not evaluated. This is an important factor affecting outcome and evaluation of compliance should therefore ideally form an integral part of any study aiming to compare outcomes of two interventions. The time from intervention to evaluation also varied widely in the study, making it difficult to determine and compare the extent of reduction of time to recovery of the two interventions under comparison. The PICO question specifically aimed at comparing the reduction in time to recovery. Therefore, time between intervention and evaluation should be standardised in order for the study to be able to address the PICO question. The retrospective nature of the study makes it difficult to address this shortcoming. There is no evidence that points towards shorter recovery times with LFTS. However, evidence can be obtained by using prospective, randomised, blinded and controlled clinical trials with large sample sizes representing a heterogeneous population of dogs with naturally occurring cranial cruciate ligament disease. There is paucity in such studies.

The RCVS Knowledge Canine Cruciate Registry aims to plug this evidence base gap by collecting data from practitioners in the UK performing surgery to address cruciate ligament disease in dogs. This initiative may provide the much lacking, albeit needed, evidence to inform treatment choices for practitioners and owners alike (www.caninecruciateregistry.org). Although participation in the initiative is limited to dog owners and practitioners registered and performing cruciate surgery in the UK, results from data collected can, hopefully, be extrapolated to any heterogenous population of dogs worldwide.

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