BACKGROUND: No surgical management is better than another regarding functional recovery for trapeziometacarpal joint osteoarthritis. Metacarpophalangeal (MCP) hyperextension, directly due to the shortening of thumb height, appears to be a factor of poor prognosis. HYPOTHESIS: MCP hyperextension can be corrected by implantation of a trapeziometacarpal prosthesis (TMP), as opposed to trapeziectomy and ligamentoplasty (TL), and pinch strength is greater with TMP in this indication. MATERIAL AND METHODS: Sixty-nine patients (41 TMP and 28 TL) were retrospectively evaluated. The following were evaluated: pain, mobility of the metacarpophalangeal joints, palmar grip and pinch strength. Thumb height was measured on radiographs as a post/preoperative ratio. RESULTS: The mean follow-up was 20 months (6-38). The TMP group showed greater reduction of the metacarpophalangeal hyperextension in all hyperextension groups, especially hypertension >30°, compared with TL. The TMP group provided significant greater pinch strength in all the subgroups with preoperative MCP hyperextension. Patient with postoperative MCP hyperextension had a significant lower grip and pinch strength compared with patient without MCP hyperextension. Radiographic analysis showed that thumb height changes were related to the degree of preoperative hyperextension. Postoperatively, patients with postoperative MCP hyperextension had a significant lower thumb height than patient without MCP hyperextension. DISCUSSION: Metacarpophalangeal hyperextension appears to be a factor of poor prognosis for surgical treatment of trapeziometacarpal osteoarthritis when it is not managed. TMP provides better metacarpophalangeal stabilization by restoring thumb length and would avoid surgery on the metacarpophalangeal joint. TMP may be recommended in patients having symptomatic trapeziometacarpal joint osteoarthritis and MCP joint hyperextension. LEVEL OF EVIDENCE: III, retrospective observational case control study.