Partial avulsion of the ulnaris lateralis and enthesiopathy of the lateral epicondyle of the humerus in a thoroughbred race horse

Abstract

Background: There is relatively little literature on elbow disease in the horse. The only published reports on soft tissue conditions describe collateral ligament and biceps brachii injuries. Case presentation: A three-year old Thoroughbred gelding presented with a history of acute onset right forelimb lameness of less than one week duration, one month after commencing training in a National Hunt racing yard. Physical examination and peri-neural anaesthesia failed to localise the lesion. Lameness was localised to the distal humerus by nuclear scintigraphy and intra-articular anaesthesia. A partial avulsion of the tendinous origin of the ulnaris lateralis and enthesiopathy of the lateral humeral epicondyle was diagnosed on ultrasonography. Ultrasonographic findings were loss of longitudinal fibre pattern, a discrete hypo-echoic region within the ulnaris lateralis tendon of origin, and remodelling of the lateral epicondyle of the right humerus at the site of the origin of the ulnaris lateralis. No abnormalities were identified on radiography. The lameness did not resolve with rest, but was successfully treated with extra corporal shockwave therapy (ECSWT) and intra-lesional corticosteroid injections. Conclusion: This is the first report of partial avulsion of the ulnaris lateralis and enthesiopathy of the lateral humeral epicondyle in the horse. In contrast to other reported soft tissue conditions of the elbow, this horse had a successful return to work. This case highlights the value of ultrasonography in assessing peri-articular soft tissues, and the importance of pain relief as treatment in some soft tissue injuries.