Impact of combining medial capsule interposition with modified scarf osteotomy for hallux valgus.

Objectives: To clarify the effect of combining medial capsule interposition with modified scarf osteotomy for hallux valgus. Methods: A multicenter, retrospective study included 64 cases [59 osteoarthritis patients (excluding rheumatoid arthritis); age 68.8 years, range 40-93 years] of modified scarf osteotomy which were performed from 2013 to 2017 and followed for 26.6 (range, 13-50) months. Patients were treated by either (1) without medial capsule interposition (33 cases) or (2) combined with interposition (31 cases) at each senior surgeon's discretion. The Japanese Society for Surgery of the Foot (JSSF) hallux metatarsophalangeal (MTP)-interphalangeal scale was evaluated along with radiographic parameters (hallux valgus angle [HVA], first and second metatarsals intermetatarsal angles, and Hardy grade). Results: All JSSF scale and radiographic parameters were similar at baseline and significantly improved at final follow-up in both groups (pre-operation vs. final follow-up: p  < .001). However, compared to without interposition group, interposition group showed significantly higher improvement in the JSSF scale (pre-operation to final follow-up: p value between the two groups at final follow-up) for pain (without interposition: 19.4-34.2, interposition: 18.4-37.1; p  = .02), function (without interposition: 20.8-33.6, interposition: 18.3-36.6; p  = .005), total score (without interposition: 41.5-81.8, interposition: 38.5-88.5; p <  .001), and the MTP joint space (without interposition: 1.4-1.5 mm, interposition: 1.6-2.6 mm; p <  .001) with significant correlation between the total JSSF score ( r  = .40; p  = .001). Conclusion: Combining medial capsule interposition with modified scarf osteotomy significantly improved mid-term clinical outcomes.