Thumb metacarpophalangeal arthritis may affect overall hand function more than expected because pain and instability compromise pinch and grip strength. Implant arthroplasty represents one option in the treatment of deformity, destruction, and instability at the metacarpophalangeal joint level. Appropriate use of implant arthroplasty requires careful evaluation of the overall deformity and the status of the interphalangeal joint. If the interphalangeal joint is likely to require fusion--either simultaneous with metacarpophalangeal surgery or subsequently--then implant arthroplasty may be the best treatment option for the metacarpophalangeal joint.