DIAGNOSIS AND MANAGEMENT OF TWO CASES OF TROCHLEAR RIDGE FRACTURES IN DOGS.

Abstract

Trochlear ridge fractures are extremly rare findings in small animals. In the literature to our knowledge only two cases have been described in dog. Two dogs, an adult male German Sheperd and an adult female Alentejo Mastiff were both presented for left hindlimb lameness with a two weeks duration due to probable distal extremity trauma. At the orthopaedic examination both dogs showed distal swelling, non-weight bearing lameness and pain on extension of the talocrural joint. The female dog presented a wound over the lateral aspect of the joint with marked lateral instability of the tibiotarsal joint suggesting lateral collateral ligament rupture or lateral malleolus fracture. Dorsoplantar, lateral and medial radiographs of the tarsus revealed significant soft tissue swelling over the lateral aspect of the tarsus and widening of the joint space over the lateral trochlear ridge of the talus. A fracture of the lateral ridge was appreciated upon evaluation of the flexed dorsoplantar view. In the case of the female dog a lateral malleolus transverse fracture associated with a complete rupture of the tibiotarsal collateral lateral ligament was also observed. In both cases fractures were surgically repaired via a dorsolateral approach to the talus without fibular osteotomy. The fragment was manually reduced and secured with a 2 mm cortical screw placed in lag fashion. An antirotational kirchner wire of 1,2 mm was placed as an ancillary osteosynthesis method in both dogs. The fibular fracture was reduced and fixed with two 1,6 mm Kirshner wires and a tension band composed of 1 mm cerclage wire. The collateral ligament rupture was addressed by bonne tunels tecnhique in distal tíbia and fourth tarsal bone using a 100 lb nylon thread placed in a figure of eight secured by two crimps. In the former case a fiber glass bivalved cast was used for six weeks to protect the ligament prosthesis. The patients made a complete clinical recovery, complete bone union was achieved at 8 weight weeks and evidence of mild osteo-arthritis was noted on postoperative radiographs. However, a residual lameness was permanent in the case of the female dog.