Hallux valgus (HV) is a progressive foot deformity in which the first metatarsophalangeal (MTP) joint is affected. The relationship between the dome height of the first metatarsal head and the HV deformity has not been studied previously. This study aimed to investigate a possible relation of the dome height of the first metatarsal head with articular alignment and the hallux valgus angle (HVA), which is frequently used to evaluate HV.
A total of 129 feet of 68 patients were included in the study. Anteroposterior digital radiographic images of the foot taken in a weightbearing, standing position were used to assess the HVA, dome height, and shape of the first metatarsal head and the alignment of the MTP joint. The dome height of the first metatarsal head is the vertical distance from the base to the highest point of the articular surface doming. The alignment was categorized into three groups: aligned, deviated, and subluxated. Patients were assigned into three groups based on the HVA: Normal, Mild HV and Moderate HV.
A statistically significant, positive correlation was found between the HVA and the dome height of the first metatarsal head (r = 0.293, P = 0.001 and P < 0.05). The dome height was significantly lower in the patients with a normal HVA than those with a high HVA (P1 = 0.042, P2 = 0.039 and P < 0.05, respectively). The dome height of the first metatarsal head was found significantly higher in feet with subluxation, compared to feet aligned and deviated (P1 = 0.001; P2 = 0.0089 and P < 0.05, respectively).
Our study results suggest that HV deformity may be related to an increased dome height and the measurement of the dome height of the first metatarsal head might be used to evaluate an anatomic tendency toward HV development.