Long-term Outcomes of Silastic Arthroplasty of the Thumb Metacarpophalangeal Joint

Background: Silastic metacarpophalangeal arthroplasty (SMPA) has proven to be a durable option for end-stage arthritis in the non-thumb digits, while fusion has been the mainstay procedure for the thumb metacarpophalangeal joint (MP). Few studies exist to comment on the viability of thumb MP arthroplasty. This study reports both survival and objective outcomes following SMPA of the thumb. Methods: In an institutional review board-approved retrospective study, we identified 18 patients who underwent thumb SMPA at a tertiary academic center by 3 board-certified hand surgeons. Primary outcome measures were implant survival and post-operative complications. Secondary outcomes measures were quick Disabilities of the Arm, Shoulder, and Hand (quickDASH) scores, brief Michigan Hand Questionnaire (bMHQ), and postoperative pain as rated by the numerical rating scale. Results: Mean quickDASH and bMHQ scores at final follow-up were 35.6 and 70.6, respectively. The most common short-term complication was clinical deformity, followed by instability. The sole long-term complication was an implant dislocation in a previously asymptomatic patient. All patients reported reduction in pain. Three patients were indicated for revision surgery, 2 for persistent instability, and 1 for implant dislocation. Primary survivorship was 83% at mean follow-up of 5.8 years. Conclusions: Thumb SMPA is a viable option for end-stage arthritis. Pain relief in our series was unanimous. Among those that reported persistent symptoms or required revision, a majority had one or more key preoperative risk factors for failure as currently reported in literature. Larger, prospective series are needed to prove superior longevity and functional outcomes of thumb SMPA versus fusion.