Union Rates and Complications After Thumb Metacarpophalangeal Fusion

Background: Fusion of the thumb metacarpophalangeal joint (MPJ) can be performed using tension band wiring (TBW) or plate and screw (PS) fixation. This study evaluated results and complications using these techniques. Methods: A retrospective review of patients who underwent thumb MPJ fusion at our institution from 2010 to 2016 was performed. Patients with >1 year follow-up were included. Demographic information, indication for fusion, time to fusion, and complications were collected. Final radiographs were examined and alignment measured. Results: There were 56 thumbs in 53 patients (42 women and 11 men) including 12 TBW and 44 PS. The mean age was 60.9 years, and follow-up was 32.4 months. Twenty-eight of 44 plates were nonlocking, and 16 were locking. Of the locking plates, 7 of 26 used all locking screws, and 9 of 26 had a combination of locked and nonlocked screws. The mean flexion angle for TBW was 16.5° and PS was 12.8°. The mean coronal angle for TBW patients was 4.0° ulnar and PS was 2.5° ulnar. The overall union rate was 95%. There were 12 complications, 9 in the PS group. The TBW complications were painful hardware requiring removal. Eight complications in the PS group occurred in patients with locked plates. Five of the delayed or nonunions occurred in patients with locked plates and 4 of these were in plates with all screws locked. Conclusion: Complications using PS or TBW are not infrequent. Alignment with both techniques is similar, but use of locked plates specifically increases the rate of delayed or nonunions. We do not recommend routine use of locked plates for fusion of the thumb MPJ.