Finite element analysis of pathogenesis of osteoarthritis in the first carpometacarpal joint.

Stress distribution in the first carpometacarpal joint was analyzed in 49 cadaveric hands using the finite element method to clarify the pathogenesis of osteoarthritis in the joint. The results of the finite element method analysis were compared with those of the contact pressure distribution in the first carpometacarpal joint of cadaveric specimens using pressure-sensitive film, and with the simple roentgenographical and microradiographical manifestations of spur formation, and with histological findings of osteoarthritis to verify the accuracy of the models of computer simulation models. The comparison of these results showed that osteoarthritic changes of the first carpometacarpal joint were found in areas where stress was concentrated during movement of the joint. The saddle shape of this joint is essentially well-designed for the dispersion of normal stress, however minimal displacement due to instability could easily induce osteoarthritis. Furthermore the shallow trapezial configuration may contribute to the high incidence of osteoarthritis changes. The finite element method helped clarify the relationship between stress patterns and osteoarthritis response.