Characterization of anatomic communications of the fetlock in cattle, using intra-articular latex injection and positive-contrast arthrography

OBJECTIVE: To evaluate the frequency and sites of communication between the lateral and medial synovial sacs of the metatarsophalangeal or metacarpophalangeal joints in cattle. ANIMALS: 188 limbs were obtained from 55 fresh bovine cadavers submitted for necropsy because of problems unrelated to the fetlocks. PROCEDURE: In each ox, lateral or medial synovial sacs of each fetlock were randomly assigned. Joints were injected with a mixture of latex and barium sulfate. Communication between 2 joints was determined by presence of latex and contrast material in a joint adjacent to the injected joint by examining frozen sections and use of positive-contrast arthrography. RESULTS: Communication between the 2 synovial sacs existed in 186 of 188 (98.9%) specimens. The communication site between lateral and medial synovial sacs was located at the level of the proximal sesamoid bones, between the distal aspect of the interdigital band of the axial branch of the interosseus muscle and the metacarpal or metatarsal bone. CONCLUSIONS AND CLINICAL RELEVANCE: Although communication between the lateral and medial synovial sacs did not exist in 2 specimens, the fetlock in cattle can be treated as 1 compartment.