New-generation implant arthroplasties of the finger joints.

Prosthetic replacement in the hand must address such unique challenges as preservation of the collateral ligaments, tendon balancing, and stability. Some recently developed implant arthroplasties of the metacarpophalangeal and proximal interphalangeal joints have anatomically designed articular components; others have non-cemented, press-fit, carefully contoured intramedullary stems. The rationale behind developing the unlinked or semiconstrained prosthesis with anatomic geometry is that it would create balanced forces across the joint. Low-profile, anatomically designed implants limit the amount of bone removed and preserve the integrity of the collateral ligaments. A metacarpophalangeal joint implant with an elliptical metacarpal head and a nonfixed center of rotation can enhance stability in flexion through greater articular contact. A proximal interphalangeal joint implant that preserves the collateral ligaments also can achieve improved stability. Component loosening is not an early complication with these recent designs, and arc of motion is satisfactory.