Background: Recurrence of the hallux valgus deformity has various causes, and the incomplete reduction of sesamoids may be one of the important issues. However, we have seen several patients with postoperative lateral sesamoid displacement on anteroposterior (AP) standing radiographs who did not experience hallux valgus recurrence. Therefore, we hypothesized that lateral displacement of the sesamoid on AP standing radiographs does not cause hallux valgus recurrence. Methods: The study included 269 feet (185 patients) with hallux valgus treated with distal chevron metatarsal osteotomy. Mean patient age was 64.26 (range, 15-80) years. Patients were followed up for an average of 33.85 (range, 12-228) months between April 2002 and December 2019. The patients were divided into 4 groups, according to the presence or absence of hallux valgus recurrence and sesamoid reduction. Results: During outpatient follow-up, we discovered 99 feet (42.1%) in which hallux valgus did not recur despite lateral sesamoid displacement (grade IV-VII) on AP standing radiographs. Hallux valgus angle (HVA, 2.7 to 7.9 degrees), intermetatarsal angle (IMA, 4.6 to 6.2 degrees), and sesamoid grades (2.1 to 3.5) all deteriorated over time after surgery, and each indicator was statistically significantly altered, and changes in the 3 indicators had a statistically significant positive correlation. Changes in HVA and IMA between feet with and without sesamoid reduction on AP standing radiographs increased over time, with the differences in HVA (2.9 degrees) and IMA (0.9 degrees) being significant at final follow-up ( P < .05 for each). Regardless of whether sesamoid reduction was achieved on AP standing radiographs, the final analysis showed that HVA and IMA in both groups worsened over time. Further, there were no differences between the 2 groups in the patterns of change over time. Conclusion: In our cohort, postoperative sesamoid position on AP standing radiographs was not associated with hallux valgus recurrence based on radiographic criteria. Level of Evidence: Level III, retrospective comparative study.

Background: Recurrence is one of the most common complications following hallux valgus surgery. Moreover, hallux varus occurs in cases of overcorrection. We aimed to quantitatively measure, using radiographic examination, the dynamics of the soft tissues that act on deformities (recurrence of valgus and occurrence of varus) after the surgery. Methods: This retrospective single-institution study included 60 patients (98 feet) who underwent hallux valgus surgery between 2009 and 2018. According to radiographic findings of the foot under weightbearing conditions at postoperative month 1, we examined the tendons’ pathway and calculated the forces on the first metatarsophalangeal joint, which we termed the deformity force angle (DFA). We compared whether there was a significant difference in DFAs between the groups in which deformities occurred and those in which deformities did not occur after correction. In addition, the DFA was compared to known radiographic measurements of hallux valgus recurrence (hallux valgus angle, distal metatarsal articular angle, intermetatarsal angle, and sesamoid position) to assess association with recurrence. Results: We observed a significant difference in the DFA between patients with and without hallux valgus recurrence ( P < .001) and between those with and without hallux varus ( P < .001) based on standing radiographs taken at a minimum of 6 months postoperation. For predicting the deformities, the areas under the curve were 0.863 (hallux valgus recurrence) and 0.831 (hallux varus occurrence), respectively, which was greater than other factors evaluated. The DFA values greater than 9.5 degrees and less than 5.5 degrees were associated with the recurrence of valgus and occurrence of varus, respectively. Conclusion: In our study, DFA was associated with hallux valgus recurrence when it exceeded 9.5 degrees and hallux varus when it was less than 5.5 degrees. Moreover, in the hallux valgus surgery we performed, a DFA from 5.5 to 9.5 degrees appeared to be a “safe zone” for preventing early deformity after surgery. Level of Evidence: Level III, prognostic.