Relationship Between the Relative Length of the Second Metatarsal and Occurrence of Metatarsalgia in Patients With Hallux Valgus

Background: Patients with hallux valgus (HV) may develop metatarsalgia, which is partly attributed to second metatarsal relative length (RL2M). However, no study has analyzed RL2Ms measured by various methods as predictors for metatarsalgia in HV patients. This study aimed to investigate the predictors for metatarsalgia in HV patients and calculate the cutoff values for metatarsalgia in preoperative planning for lesser metatarsal shortening osteotomy. Methods: In this retrospective cohort study, 103 female patients (131 feet) with HV were investigated for metatarsalgia (metatarsalgia-positive [MP] group: 55 feet; metatarsalgia-negative [MN] group: 76 feet). The HV angle (HVA) and intermetatarsal angles (IMAs) (1/2 and 1/5), lateral talo–first metatarsal angle, calcaneal pitch angle, first metatarsal–medial cuneiform angle, and first metatarsal lift (LIFT) were measured using weightbearing radiographs. RL2Ms were assessed using the 4 methods described by Morton and Nilsonne (method A), Coughlin (method B), Hardy and Clapham (method C), and Kumano (method D). RL2M (method D) was calculated as the ratio of this distance to the second metatarsal length. These measurements were compared between the groups. Multivariate logistic regression analysis was performed to determine the predictors of developing metatarsalgia. The cutoff values were calculated using receiver operating characteristic curve analysis. Results: HVA, IMAs (1/2 and 1/5), LIFT, and RL2M (method D) were significantly higher in the MP group than in the MN group. In the multivariate analysis, HVA and RL2M (method D) were independent predictors for metatarsalgia. The cutoff values for HVA and the value and ratio of RL2M (method D) were 37.0 degrees, 13.1 mm, and 18.8%, respectively. Conclusion: HVA and RL2M measured by method D were independently associated with the occurrence of metatarsalgia in HV patients.