Intermetatarsal angle after first metatarsophalangeal joint arthrodesis for hallux valgus

Background: First metatarsophalangeal (MTP) joint arthrodesis is commonly done for hallux valgus; with an arthritic joint. In patients with a wide preoperative first intermetatarsal (IM) angle an important question is whether the metatarsus varus will be corrected by the first MTP joint fusion alone or whether an additional basal osteotomy is necessary. Methods: The charts and radiographs of 20 patients who had arthrodesis of the first MTP joint were retrospectively reviewed. All 20 patients were female with a mean age of 54.2 (range 42 to 78) years. Either a Hallu-S-(R) plate (Integra Life Sciences, Nudeal, France) or two crossed screws were used to stabilize the arthrodesis. The IM angles were measured independently by two individuals on weightbearing preoperative, 6-week postoperative, and final followup films. The final followup radiographs were taken at an average of 13.7 (range 6 to 30) months after surgery. A Student West was used to evaluate the changes in the IM angle and interobserver variations. Results: The mean preoperative IM angle was 16.65 (range 12 to 26) degrees. The mean postoperative IM angle was 10.35 (range 6 to 15) degrees. The mean IM angle at final followup was 8.67 (range 5 to 12) degrees. The mean change between preoperative IM angle and IM angle at final followup was 8.22 (range 4 to 14) degrees. This change of the IM angle was statistically significant (p < 0.0001). Conclusions: These results indicate that in patients with severe hallux valgus and first MTP joint degeneration arthrodesis can significantly correct the IM angle without the addition of a basal osteotomy.