Imagine this clinical scenario: you are presented with a 10kg Fox Terrier with a complete rupture of the cranial cruciate ligament of the left stifle. The right stifle is unaffected. You and your team are experienced in performing the lateral fabellar suture (LFS) technique to manage cranial cruciate ligament disease in small dogs, typically with good outcomes. But you have recently attended a tibial tuberosity advancement (TTA) wet lab and were advised that this technique is suitable for dogs of all sizes. In order to advise the client appropriately on which technique would be most suitable for their dog, you search for evidence comparing the long-term outcomes of these two procedures in dogs weighing under 15kg.
The evidence
There is no evidence that directly answers this clinical question by a comparison of the functional outcomes of TTA and LFS for unilateral cranial cruciate ligament disease in dogs weighing less than 15kg. However, two prospective clinical trial studies (Nelson et al., 2012; Krotscheck et al., 2016) compared the long-term functional outcomes of TTA and extracapsular reconstruction (ECR) by LFS, though dogs under 15kg were excluded from the studies.
Although the results of the two studies suggest better long-term functional outcomes in the TTA group compared to the ECR (LFS) group, both studies excluded dogs weighing less than 15kg
In the 2016 study by Krotscheck et al., dogs with a diagnosis of unilateral cranial cruciate ligament disease were treated with TTA (n= 14), TPLO (n= 15) or ECR (n= 23), and compared with a control group of normal adult dogs (n= 80). Data for the control group and TTA group in the 2016 study were reported and compared to data for the control group, TPLO group and ECR (LFS) group reported in the 2012 study by Nelsonet al. At 12 months post-operatively, the TTA group had a better functional outcome at walk than the ECR (LFS) group and was indistinguishable from the control group, and the functional outcomes of the TTA and the ECR (LFS) groups were indistinguishable at the trot but inferior to the control group. The TTA group had more post-operative complications than the ECR (LFS) group. At 12 months post-operatively, the TPLO group had functional outcomes indistinguishable from the control group at both the walk and the trot, suggesting superior long-term functional outcomes of the TPLO group to both the TTA and ECR (LFS) groups.
Although the results of the two studies suggest better long-term functional outcomes in the TTA group compared to the ECR (LFS) group, both studies excluded dogs weighing less than 15kg, thus the results may not be applicable to this clinical question.
A 2015 study by Di Dona et al. compared objective validated long-term functional outcomes of TTA and LFS using force plate analysis. Dogs in both groups had good to excellent outcomes, but kinematic results indicated superior surgical outcomes with the TTA group at the six-month follow-up. However, the paper did not specify whether the study population included dogs weighing below 15kg, making it difficult to determine the relevance of the evidence to the clinical question.
Dogs in both groups had good to excellent outcomes, but kinematic results indicated superior surgical outcomes with the TTA group at the six-month follow-up
Conclusion
There is currently no evidence comparing TTA or LFS techniques in dogs weighing under 15kg, so veterinary surgeons should be guided by the patient’s best interests when recommending either procedure to clients. Future studies are necessary and would ideally be blinded randomised controlled clinical trials that address the specific weight class of under 15kg with an objective assessment of long-term functional outcomes of TTA and LFS.
A reason for the lack of evidence relevant to the specific weight class might be due to previous recommendations that dogs weighing less than 15kg do not require surgery
A reason for the lack of evidence relevant to the specific weight class might be due to previous recommendations that dogs weighing less than 15kg do not require surgery. This was based on a 1984 study by Vasseur, wherein 85.7 percent of dogs weighing under 15kg were considered clinically normal after an average follow-up period of 36.6 months following conservative non-surgical management, compared to 19.3 percent of dogs weighing over 15kg after an average follow-up period of 49.1 months. It has since been demonstrated that conservatively managed dogs develop more severe osteoarthritis in the long term than surgically managed dogs. In view of this, surgery in one form or another is recommended (Innes, 2012; Hamilton, 2016; Mölsä et al., 2014). The literature does not specify whether this has been demonstrated in dogs under 15kg, so the relevance of this observation regarding small dogs cannot be determined.
It has since been demonstrated that conservatively managed dogs develop more severe osteoarthritis in the long term than surgically managed dogs. In view of this, surgery in one form or another is recommended
The veterinary community does not, at present, have a strong evidence base to know which surgical techniques for canine cranial cruciate ligament disease have the best outcomes.
The Canine Cruciate Registry (CCR) is RCVS Knowledge’s answer to this gap in veterinary care knowledge. It is an electronic system that generates a series of questionnaires for vets and dog owners to complete over the course of the dog’s care and to monitor their long-term progress afterwards. The aim is to improve our ability to evaluate the benefits of particular procedures or implants and to recognise any quality concerns more quickly with new techniques, resulting in improved patient safety.
The full Knowledge Summary can be read in RCVS Knowledge‘s open access journal Veterinary Evidence.
