Retrospective review of long-term radiographic outcomes of first metatarsophalangeal joint arthrodesis for hallux valgus

Hallux valgus is a common disorder of the foot that is often coupled with metatarsus varus, which may cause pain, discomfort and affect shoe wear. Studies have shown that the first intermetatarsal angle (IMA) can be significantly reduced after first metatarsophalangeal joint arthrodesis alone; however, the presence of long-term interval change in the first IMA after first MTPJ arthrodesis is still controversial. This retrospective observational study aims to evaluate the radiographic outcomes of first metatarsophalangeal joint arthrodesis for hallux valgus deformities. Patients who received first MTPJ arthrodesis for management of hallux valgus deformity between January 2011 and December 2018 were reviewed. Angular measurements of the HVA and first IMA were performed on X-Rays of these patients taken at pre-operation, early post-operative (4–6 weeks) and at final follow up. Patients who received X-rays at 1 year, 2 years, and 4 years post-operation, were also evaluated for first IMA and HVA on these X-rays. About 88 patients were evaluated, with final follow up ranging between 9 and 565 weeks. The pre-operative mean HVA of 42.6 (95% CI [40.3, 44.9]) degrees was significantly reduced (p < 0.001) to a mean HVA of 10.4 (95% CI [8.9, 11.7]) degrees at 4–6 weeks after first MTPJ arthrodesis. The pre-operative mean first IMA of 16.9 (95% CI [16.2, 17.7]) degrees was significantly reduced (p < 0.001) to a mean IMA of 11.8 (95% CI [11.2, 12.5]) degrees at 4–6 weeks after first MTPJ arthrodesis. There was a small statistically significant reduction in the first IMA between early post-operation and at 1 year post-operation (0.96 degrees – 1.87 degrees, depending on subgroup). First metatarsophalangeal joint arthrodesis is effective in reducing the widened first IMA associated with hallux valgus deformity, and is able to maintain the correction upon long-term follow-up.