Four-Strand Versus 2-Strand Suture-Button Constructs in First Carpometacarpal Arthroplasty: A Biomechanical Study.

Background: Suture-button fixation is an alternative to no fixation, first metacarpal distraction techniques, or Kirschner wire fixation after trapeziectomy in treatment of first carpometacarpal (CMC) arthritis. A 4-strand suture-button construct requires a 2.7-mm tunnel, whereas a 2-strand construct requires a 1.1-mm tunnel, potentially decreasing the risk of metacarpal fracture. We compared stability and failure criteria of 4-strand versus 2-strand construct in a biomechanical model of first CMC joint arthroplasty. Methods: Ten fresh-frozen matched pairs of human cadaveric hands were randomized to receive a 4-strand or 2-strand suture-button device. Trapeziectomy and fluoroscopic measurement of the fixed posttrapeziectomy space was performed before and after cycling 1000 times at 0.2 Hz in a custom loading device. The constructs were loaded to failure and failure mechanism was noted. Results: There was no significant difference between the groups in unfixed posttrapeziectomy, fixed precyclic loading, or postcyclic loading height. No difference in pinch pressure was found in any group. No difference in load to failure was observed. The 4-strand device failed through the first ray in 8 of 11 specimens, and the suture of the 2-strand device failed in 5 of 9 specimens. Conclusions: The 4-strand and 2-strand suture-button constructs provide comparable biomechanical stability for first CMC arthroplasty. If construct stability is similar between these procedures, the smaller tunnel used with the 2-strand construct may offer an advantage.

Thumb carpometacarpal arthroplasty using an absorbable interference screw for flexor carpi radialis ligament reconstruction.

Few surgical techniques that address advanced thumb carpometacarpal osteoarthrosis specifically allow early mobilization postoperatively. After trapeziectomy, we carry out a ligament reconstruction using an absorbable interference screw to secure a flexor carpi radialis tendon autograft within the first metacarpal base. Theoretically, superior tendon graft fixation strength allows early mobilization within 2 weeks postoperatively. We have retrospectively compared our clinical results using this technique with another group of patients who underwent traditional ligament reconstruction and tendon interposition as described by Burton and Pellegrini. There were no differences in the verbal pain score, satisfaction rating, or DASH scores between groups. There was a statistically significant decrease in trapezial space ratio both at rest and with stress for the experimental group. Although the clinical significance of this finding is largely unknown, it did not correlate with clinical outcome in our patients. Although no conclusions could be drawn regarding early mobilization after thumb carpometacarpal arthroplasty, further studies are planned to investigate this intriguing aspect of postoperative care. In this article, we present the details of the surgical technique and postoperative rehabilitation.