ANATOMICAL AND BIOMECHANICAL STUDIES OF THE PATHOGENESIS OF TRAPEZIOMETACARPAL DEGENERATIVE ARTHRITIS

An anatomical and biomechanical study of the stabilizing ligaments of the thumb trapeziometacarpal joint was conducted on 32 hand specimens. Five main ligamentous structures could be identified. The mechanical properties (in particular, strength) of the five ligaments using a str ain-rate failure test were determined and evaluated quantitatively. Th e maximum tensile strength of each ligament was correlated with the co ndition of the trapeziometacarpal articular cartilage. In studying the anterior oblique ligament, maximum strength decreased from Grade 0 to Grade 1 by 51%. With the first intermetacarpal ligament, the drop fro m Grade 1 to Grade 2 was 53%. With the posterior oblique ligament, the decrease was closely related to the grade of the deterioration of the trapeziometacarpal articular surface. These three ligaments also sign ificantly decreased in strength with age. Our results may suggest that the anterior oblique ligament, intermetacarpal ligament and posterior oblique ligament play a large role in stabilizing the trapeziometacar pal joint and that the decrease in their strength is related to the pa thogenesis of trapeziometacarpal osteoarthritis.