Radiographic analysis of the effects of first metatarsal rotation in hallux valgus surgery

Abstract

Objective: To evaluate whether the initial degree of metatarsal rotation interferes with the surgical correction of severe hallux valgus. Methods: A retrospective study was performed using weight-bearing AP radiographs to measure first metatarsal rotation based on the shape of the lateral edge of the metatarsal head and the hallux valgus (HVA) and intermetatarsal (IMA) angles. Participants were then classified into two groups. Those with less rotational deformity were placed in the negative pronation group, while those with greater rotational deformity were placed in the positive pronation group. Mean HVA and IMA correction were calculated and compared between groups. Participants underwent the modified Lapidus procedure with correction of pronation. Results: Data were collected for 26 feet with hallux valgus. The negative and positive pronation groups contained 14 and 12 feet, respectively. Successful surgical correction of pronation was observed in 11 of the 12 feet, which were ultimately classified in the negative pronation group based on postoperative radiographs. The negative pronation group showed a mean difference of 15.05o in the HVA and 4.20o in the IMA. The positive pronation group showed a mean difference of 14.22o in the HVA and 3.2o in the IMA. These values did not significantly differ between groups. Conclusion: The initial degree of pronation does not affect the degree of angular correction as long as metatarsal rotation is also addressed. Level of Evidence IV; Diagnostic Studies; Case Series.