Radiological Outcomes of Third Generation Minimally Invasive Chevron Akin Osteotomies (MICA) for Hallux Valgus

Abstract

Category: Bunion Introduction/Purpose: Minimally invasive surgery for hallux valgus has significantly increased in popularity recently due to smaller incisions, reduced soft tissue trauma, and the ability to achieve large deformity corrections compared to traditional treatments. This study aimed to investigate the radiological outcomes and degree of deformity correction of the intermetatarsal angle (IMA) and the hallux valgus angle (HVA) following third generation (using screw fixation) Minimally Invasive Chevron and Akin Osteotomies (MICA) for hallux valgus. Methods: A single surgeon case series of patients with hallux valgus underwent primary, third generation MICA for hallux valgus. Pre- and post-operative (6 weeks after surgery) radiological assessments of the IMA and HVA were based on weight-bearing dorso-plantar radiographs. Radiographic measurements were conducted by two foot & ankle fellowship trained consultant surgeons (RR, DG). Paired t-tests were used to determine the statistically significant difference between pre- and post-operative measurements. Results: Between January 2017 and December 2019, 401 MICAs were performed in 274 patients. Pre- and post-operative radiograph measurements were collected for 348 feet in 232 patients (219 female; 13 male). The mean age was 54.4 years (range 16.3-84.9, standard deviation (s.d.) 13.2). Mean pre-operative IMA was 15.3° (range 6.5°-27.0°, s.d. 3.4°) and HVA was 33.8° (range 9.3°-63.9°, s.d. 9.7°). Post-operatively, there was a statistically significant improvement in radiological deformity correction; mean IMA was 5.3° (range -1.2°-16.5°, s.d. 2.7°, p<0.001) and mean HVA was 8.8° (range -5.2°-24.0°, s.d. 4.5°, p<0.001). The mean post-operative reduction in IMA and HVA was 10.0° and 25.0° respectively. Conclusion: This is the largest case series demonstrating radiological outcomes following third generation Minimally Invasive Chevron and Akin Osteotomies (MICA) for hallux valgus to date. These data show that this is an effective approach at correcting both mild and severe hallux valgus deformities. Longer term radiological outcome studies are needed to investigate whether there is any change in radiological outcomes. Correlation with patient reported outcomes is planned.