Weight-bearing CT Scan Analysis in Hallux Valgus Treated with Minimally Invasive Surgery

Abstract

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: Hallux valgus (HV) is one of the most prevalent foot deformities. Coronal metatarsal rotation (pronation) has been recognized as a key element in HV deformity and an important prognostic factor for recurrence. With the advent of weight-bearing CT (WBCT), accurate pronation measurement has improved. The Minimally Invasive Bosh Akin (MIBA) surgery has proven to be effective in treating HV deformity. The literature analyzing correction of pronation in HV surgery is lacking. Purpose: To compare the transverse and coronal plane deformity correction by WBCT in HV patients treated with MIBA surgery. Methods: We retrospectively analyzed HV deformity in patients who underwent MIBA surgery with preoperative and at least 3 months postoperative WBCT for comparison. Intermetatarsal angle (IMA), hallux valgus angle (HVA), and alpha angle (AA) for first metatarsal pronation were measured by 2 different observers. The intraclass and interclass correlation were determined. Pre and postoperative measurement changes were established by T-test for related samples. the p-value for statistical significance was set at < 0.05. Results: 37 feet were included. Intraclass correlation was 0.97 /0.92 for IMA; 0.95/0.91 for AA and 0.99/0.97 for HVA preoperative. Postop it was 0.97/ 0.96 for IMA, 0.97/0.92 for AA, and 0.98 and 0.96 for HVA. Interclass correlation was 0.95 for IMA; 0.7 for AA and 0.82 for HVA preoperative. Postop, was 0.82 for IMA, 0.8 for AA, and 0.79 for HVA. Mean preoperative / postoperative AA was 8.9 degrees and 6.9 degrees respectively, resulting in a first ray pronation change of –2.0 degrees, p< 0.054. The media preoperative and postoperative IMA was 13.6 degrees and 6.8 degrees, demonstrating a significant change (P < .005). The media preoperative and postoperative HVA was 28.7 (8.8) and 13.1 (9.0), demonstrating a significant change (P < .005). Conclusion: To the best of our knowledge, this is the first study that evaluates the radiological changes in HV surgery with WBCT. The MIBA osteotomy for HV deformity has significant power to correct the transverse plane deformity. Even though the coronal plane deformity correction wasn’t statistically significant, it showed a strong tendency, which might be demonstrated by utilizing a bigger sample. The only measurement that didn’t have an excellent agreement was the preop AA.