Modified scarf osteotomy has a possible capability to be indicated against very severe hallux valgus deformity

Abstract Background: Generally, scarf osteotomy is recommended for moderate-severe hallux valgus (HV) deformity. Although severe HV deformity is defined to be more than 40 degree (°), this definition of angular setting includes broad range of HV angle (HVA). Actually, very severe HV deformity such as more than 60° of the HVA is often seen. At present, whether scarf osteotomy would truly contribute to maintaining the correction status against such very severe deformity is elusive. Then, in this study corrective effectiveness of modified scarf osteotomy including very severe deformity (HVA ≥ 60°) was evaluated. Methods: A retrospective, observational study of 93 feet [mean follow-up: 56.0 months after the surgery] was performed. Hallux scores of the Japanese Society for Surgery of the Foot (JSSF), a self-administered foot evaluation questionnaire (SAFE-Q), and pre-postoperative radiographic parameters were evaluated. The patients were categorized into three groups [44 feet: (mildly severe) 40° ≤ HVA < 50°, 30 feet: (moderately severe) 50° ≤ HVA < 60°, 19 feet: (very severe) 60° ≤ HVA]. Results: Both JSSF hallux and SAFE-Q score showed significant improvement in all groups, except social activity score in SAFE-Q, in very severe cases (P = 0.08). HVA also significantly improved in all groups without significant change of the HVA between post 1-month and final follow-up in each groups. No difference was seen among the three groups in complications after surgery and frequency of recurrence of HV deformity. Conclusion: Modified scarf osteotomy has sufficient possible capability to be indicated against very severe (HVA ≥ 60°) deformity, however it might be recommended until getting 60° of HVA in the perspective of clinical score improvement. Level of evidence: Level III