Impact of Preoperative Metatarsus Adductus on Surgical Correction after Triplanar Tarsometatarsal Arthrodesis

CATEGORY: Bunion; Midfoot/Forefoot INTRODUCTION/PURPOSE: Early radiographic outcomes of hallux valgus correction focusing on multiplanar deformity have shown promising results. Surgical correction for patients with preexisting metatarsus adductus is considered more challenging and results in higher recurrence rates following hallux valgus surgery. The purpose of this study was to evaluate the impact of preoperative metatarsus adductus on surgical correction following triplanar first tarsometatarsal (TMT) arthrodesis with early weightbearing for hallux valgus. METHODS: A retrospective review was performed of 57 patients (62 feet) aged 39.7 +- 18.9 years who underwent triplanar first TMT arthrodesis between 2015 and 2017 at four institutions. After the operation, patients were allowed early full weightbearing in a walking boot. Patients were grouped based on preoperative metatarsus adductus angles for comparison. Preoperative imaging was reviewed and compared to radiographic imaging at 12 months postoperative. Hallux valgus angle (HVA), intermetatarsal angle (IMA), tibial sesamoid position (TSP), lateral round sign, and sesamoid subluxation (axial) were evaluated. For statistical analysis, one-way analysis of variance (ANOVA) and chi-square tests were performed using JMP 11.0.0 (SAS Institute Inc., Cary, NC). RESULTS: Patients with a preoperative metatarsus adductus angle greater than 20 degrees had significantly higher HVA at 12 months (p = 0.0165). There were no differences in IMA or TSP at 12 months based on preoperative metatarsus adductus (p = 0.7687 and p = 0.8703, respectively). Overall recurrence rate for hallux valgus was 3.2% (2/62 patients), and both of these patients had a preoperative metatarsus adductus greater than 20 degrees. There was significantly more sesamoid axial subluxation at 12 months for patients with preoperative metatarsus adductus greater than 20 degrees (p = 0.0092). Overall, the symptomatic non- union rate was 1.7% (1/62 patients). CONCLUSION: Preoperative metatarsus adductus greater than 20 degrees resulted in higher HVA and recurrence rates at 12 months after triplanar tarsometatarsal arthrodesis. For patients with preexisting metatarsus adductus, additional consideration should be given to ensure the sesamoids are properly reduced under the crista. Future studies should compare the long-term impact of metatarsus adductus on surgical correction, recurrence, and complications after triplanar tarsometatarsal arthrodesis.