Computed Tomography Investigation of First Metacarpal Subsidence After Suture Button Suspensionplasty: A Report of Two Cases.

First metacarpal subsidence often occurs after suture button suspensionplasty (SBS) for first carpometacarpal joint arthritis. In this study, we describe computed tomography (CT) findings in two cases of first metacarpal subsidence after SBS. Case 1 was a 51-year-old right-handed male. At the final follow-up two years post-SBS, no noticeable thumb shortening was observed. CT imaging at the last follow-up showed a slight expansion of the hole in the first and second metacarpals where the suture had passed. Case 2 was a 58-year-old right-handed male. Thumb shortening was noticed three months and three weeks after SBS. At the final follow-up, two years and seven months post-surgery, CT imaging revealed significant expansion of the hole in a conical shape in the second metacarpal where the suture had passed. Our findings suggest that the expansion of the foramen where the suture passed through the metacarpals may contribute to the first metacarpal subsidence after the surgery.