Hamish is an eight year old male neutered West Highland White Terrier. He had a lateral fabellotibial suture for cranial cruciate ligament (CCL) disease six months prior to referral to VetFix. Despite initial improvement Hamish was still showing a marked weight bearing lameness on the leg.
Muscle atrophy of the quadriceps muscle group was notable and a marked medial buttress evident. Under anaesthesia the cranial drawer test was consistent with stifle instability associated with CCL rupture. Radiographic changes suggested stifle joint effusion. Marked osteophytosis was evident at the osteochondral margins of the femoral trochear ridges, the tibial condyles, the proximomedial margin of the tibia and the poles of the patella confirming moderate stifle osteoarthritis. Arthrocentesis and joint fluid sampling was also consistent with osteoarthritis with no evidence of infection.
A decision was made to perform a medial arthrotomy and a tibial plateau levelling technique. Hamish had a tibial plateau angle (TPA) of just over 30 degrees. The exact magnitude of correction necessary to achieve an acceptable post-operative plateau angle is unknown. Wide discrepancies in postoperative TPA have been reported1. When performing a cranial tibial closing wedge osteotomy I make an osteotomy at the level of the distal extent of the cranial border of the tibial tuberosity. In addition I use wire to reduce the cranial cortices whilst attempting not to make a complete osteotomy through the caudal cortex. Interestingly Apelt et al reported than only a wedge of TPA +5 degrees or +7.5 degrees achieved a post-operative TPA of about 6 degrees2. But in this study the cranial cortices were not aligned. I normally aim to make an osteotomy of the TPA minus 5 degrees and avoid excessively large wedge resections as have concerns regarding post-operative tibial length, patella baja, and caudal sloping of the tibial tuberosity with respect to the tibial shaft distal to the osteotomy. Post-operative radiographs showed a TPA of around 8 degrees in this case. Meniscal inspection also showed a small bucket handle tear to the medial meniscus. This was managed with a partial menisectomy.
Recovery and post-operative care
Hamish was hospitalized overnight and followed a recovery and physiotherapy plan as outlined in the “Care Sheets” on the VetFix website. He made a very rapid recovery and was using the leg well within a few days. Post-operative radiographs at 8 weeks confirmed osseous bridging at the osteotomy and further exercise plans were introduced including off lead exercise and hill walking.
The significance of a steep TPA is open to debate and WHWT often have an already “advanced” tuberosity of some extent making a decision to perform a TTA difficult. In addition performing a TTA in small dogs can be difficult with cage and plate placement on the tibial tuberosity. Many small dogs will improve with rest following CCL rupture however a significant proportion we see fail to thrive without surgical management. The cranial closing wedge osteotomy can be a useful procedure for this sub-section of dogs.
- Bailey CJ, Smith BA, Black AP: Geometric implications of the tibial wedge osteotomy for the treatment of cranial cruciate ligament disease in dogs. Vet Comp Orthop Traumatol 20:169, 2007
- Apelt D, Pozzi A, Marcellin-Little D, et al: Effect of cranial tibial closing wedge angle on tibial subluxation: an ex vivo study. Vet Surg 39:454, 2010