Histopathology of the palmar beak ligament in trapeziometacarpal osteoarthritis

Eighteen cadaver hands were studied to investigate the relationship between degeneration of the palmar beak ligament and articularlar disease of the t rapeziometacarpal joint. Eight of 18 joints had chondromalacia alone; 10 co ntained areas of eburnation in the palmar aspect of the joint. Beak ligamen t degeneration correlated closely with the presence of articular degenerati on; all joints with eburnation demonstrated frank detachment of the ligamen t from its metacarpal insertion site. Histologically, the collagen fibers o f the beak ligament were disorganized at the metacarpal attachment. The nor mal insertional zone of fibrocartilage was often unrecognizable on the meta carpal side and, in more degenerative specimens,an intervening synovial rec ess appeared at the palmar beak of the metacarpal. The trapezial insertion of the beak ligament showed no degenerative change. Increasingly severe car tilage disease was associated with progressive and selective degeneration o f the collagen framework of the beak ligament at its insertion onto the thu mb metacarpal. These localized histopathologic findings further support the existence of an anatomically distinct intra-articular beak ligament essent ial to the normal function of the trapeziometacarpal joint and suggest an e tiologic relationship to osteoarthritic disease. Copyright (C) 1999 by the American Society for Surgery of the Hand.