Need for concomitant Akin osteotomy in patients undergoing Chevron osteotomy can be determined preoperatively: a retrospective comparative study of 859 cases

BACKGROUND: The Chevron osteotomy is a frequently used surgical method for hallux valgus correction. This method is often combined with an Akin osteotomy. To date, clear guidelines for the implementation of an additional Akin osteotomy are missing. The purpose of this study was to elucidate the impact of concomitant phalangeal correction on the outcome after hallux valgus surgery and to define indication criteria for an additional Akin osteotomy. METHODS: Patients (859 feet) undergoing distal Chevron osteotomy at our department were retrospectively grouped into group C (Chevron, 785 feet) and group AC (Chevron plus Akin, 74 ft). Radiological assessment including the intermetatarsal angle (IMA), the hallux valgus angle (HVA), the distal metatarsal articular angle (DMAA), and the proximal to distal phalangeal articular angle (PDPAA) was performed preoperatively, postoperatively, after 6 weeks, and after 3 months. Longer-term follow-up with a mean of 36.4 months was available for 248 cases (29%). RESULTS: A significant improvement of all parameters could be found to all points of survey (p < 0.001). Loss of correction was detected for HVA (p < 0.001) and IMA (p < 0.007) with higher levels in group C. Preoperative PDPAA exceeding 8° correlated significantly with loss of HVA correction in group C (p < 0.001). CONCLUSION: The combined Chevron and Akin osteotomy allowed for better correction of the hallux valgus deformity with better maintenance of the achieved correction. Recommendation for concomitant Akin osteotomy may be determined by a preoperative PDPAA exceeding 8°. TRIAL REGISTRATION: Retrospectively registered. UN5080. LEVEL OF EVIDENCE: Therapeutic, Level III, retrospective comparative series.