Capito-Lunate Fusion with Memory Staples

Introduction Once the midcarpal joint is involved in radioscaphoid arthritis (SLAC, SNAC, or primary), a PRC is no longer indicated. The motion-preserving option is a scaphoidectomy and midcarpal fusion.

Isolated lunato-capitate (LC) fusion performed with K-wires in the 1980s were associated with up to 50% nonunion and, therefore, fell out of favor. The concept of a four-corner fusion was popularized as there was potentially more bone for a fusion mass. Dedicated implants in the form of circular plates have been designed and developed for this purpose. The major issues with these are ongoing substantial nonunion rates, as well as dorsal impingement. In particular, the ulnar side of the fixation/fusion has been problematic. Bain et al showed improved range of motion, especially in radial and ulnar deviation with removal of the triquetrum.

Our hypothesis was that we could achieve good union rates, as well as limited hardware issues, by performing a two- or three-corner fusion using dorsally applied memory staples.

Materials and Methods A retrospective case series of all patients who had two- or three-corner fusion following scaphoidectomy and triquetrectomy fixed with memory staples. Fusion rates, complications, range of motion, Mayo wrist score, and Quick DASH scores were assessed.

Results There were 18 patients and 19 wrists. Indications were SNAC (21%), SLAC (63%), other (16%). Sixty-eight percent were two-corner fusions and 32% were three-corner fusions. Follow-up averaged 13 months (6 to 50). Range of motion (ROM) averaged 41° extension and 25° flexion. Average time to union was 8.5 weeks with two nonunions (11%). Quick DASH was 15 (0 to 52) and the MWS was 77.5 (45 to 95).

Conclusion Midcarpal fusion performed using dorsal memory staples is technically feasible and associated with reasonable union rates and high patient acceptance. Excision of the triquetrum might offer improved ROM (unproven) but does not appear to be associated with any unforeseen complications.

References

Reference

1 Bain GI, Sood A, Ashwood N, Turner PC, Fogg QA. Effect of scaphoid and triquetrum excision after limited stabilisation on cadaver wrist movement. J Hand Surg Eur Vol 2009;34(5):614–617