Cruciate ligament rupture in young adult broiler knee joints.

Derangement of the caudal cruciate ligament was identified in 11 broiler fowls aged between 18 and 38 weeks. In some cases, the caudal cruciate ligament alone was ruptured, whereas, in others, the caudal meniscofemoral and meniscotibial ligaments and medial meniscus were also deranged. In some birds, ligaments were only partially ruptured but, in 5 cases, complete rupture had occurred in both knee joints. All birds showed severe lameness which, in 2 cases, could only be ascribed to caudal cruciate derangement. Degenerative changes were present in many of the ligaments which suggested that rupture may be a consequence of primary ligamentous change. Proximal tibiotarsal osteochondrosis was a frequent concomitant finding which may affect the integrity of the ligament attachment. A number of other factors including postural abnormality, obesity, and relative inactivity may predispose broilers to caudal cruciate ligament rupture.