Medial fabella bone position varies in West Highland white terriers

Abstract

OBJECTIVES: To investigate whether West Highland white terriers exhibit significant variation in the position of the medial fabella compared to both small and large breed dogs. METHODS: Criteria for the normal location of the medial fabella on a caudocranial radiograph were established. A retrospective analysis was undertaken of a consecutive series of bilateral caudocranial stifle joint radiographs from 70 West Highland white terriers, 100 small and 100 large control dogs by three reviewers. Medial fabellar location, cruciate ligament disease and medial patellar luxation were examined within and between groups. RESULTS: Abnormal medial fabellar location was identified in 70 per cent, 9 per cent and 0 per cent of West Highland white terriers, small dogs and large dogs, respectively. In the vast majority of the affected dogs, the fabella was found in a mediodistal location. Presence of concurrent cranial cruciate ligament disease or medial patellar luxation and body weight was excluded as confounding factors. CLINICAL SIGNIFICANCE: West Highland white terriers appear predisposed to, and have a high prevalence of, an abnormal mediodistal location of the medial fabella. The authors suggest this is an incidental finding and should not be confused with true pathological fabellar displacement.