Abstract
Osteoarthritis (OA) is a common disease of the first carpo-metacarpal (CMC I) joint. Biomechanical factors promoting OA are the shape of the CMC I-joint, being a biconcave-convex saddle joint with high mobility and the increased instability caused by joint space narrowing, ligamentous laxity, and direction of force transmission of the abductor pollicis longus (APL) tendon during adduction. The closing wedge osteotomy of the base of the first metacarpal is joint preserving treatment option. We combine this closing wedge osteotomy with a ligamentoplasty to stabilize the joint. In this manuscript, we provide a detailed description of the indication, discuss biomechanical aspects and the surgical technique in detail.