Hip instability in young adult, broiler fowls.

In a study of spontaneous orthopaedic disease in 104 broiler-type birds fed ad lib, 14 cases of hip instability were detected. Female birds were commonly affected and all were aged between 20 and 30 weeks. Although hip luxation was not identified, in most cases the gait abnormality could be attributed to capital femoral ligament failure. There were two main patterns of capital femoral ligament disruption; either the ligament was avulsed, together with a cartilage fragment, from its foveal attachment, or the ligament itself was partially or totally ruptured. Histological evidence suggests that repetitive trauma or acute trauma of sufficient magnitude may be necessary for ligament disruption. It is likely that the excessive weight gain of ad-lib fed birds predisposes to ligament damage.