EXTENSION METACARPAL OSTEOTOMY IN THE TREATMENT OF TRAPEZIOMETACARPALOSTEOARTHRITIS - A BIOMECHANICAL STUDY

The biomechanical effects of extension metacarpal osteotomy on contact pressures in the trapeziometacarpal joint during lateral pinch were s tudied in 20 anatomic specimens using pressure-sensitive firn. The gro ss appearance of joint surfaces was classified by severity of arthriti c disease and correlated with specimen x-ray films taken before the os teotomy. Extension metacarpal osteotomy effectively unloaded the palma r contact area in nonarthritic and moderately arthritic specimens; pri mary contact areas and zones of peak pressure were shifted from the di seased palmar compartment to the normal dorsal compartment. In contras t, the pathologically congruent contact pattern seen in end-stage oste oarthritic joints was unaffected by osteotomy. The data demonstrate th e efficacy of extension metacarpal osteotomy in unloading the palmar c ontact areas of normal and moderately arthritic joints but provide no biomechanical rationale for metacarpal osteotomy as originally describ ed in treatment of advanced trapeziometacarpal osteoarthritis.