Hallux valgus interphalangeus is more common in juvenile-onset hallux valgus than in adult-onset hallux valgus.

Background: This study aimed to compare the prevalence of hallux valgus interphalangeus (HVI) in juvenile-onset hallux valgus and adult-onset hallux valgus and to analyze the correlation between the hallux interphalangeal angle (HIA) and other radiographic parameters in juvenile-onset hallux valgus.

Methods: This retrospective study included 640 feet and 320 patients with hallux valgus (160 juvenile-onset and 160 adult-onset cases). Eight radiographic parameters were measured: HIA, hallux valgus angle, intermetatarsal angle, talonavicular coverage angle, anteroposterior talocalcaneal angle, lateral talocalcaneal angle, lateral talo-first metatarsal angle, and calcaneal pitch. The two groups were compared based on the radiographic parameters, and the correlation between the HIA and other radiographic parameters in juvenile-onset valgus was analyzed.

Results: The prevalence of HVI in juvenile-onset hallux valgus (63%) was higher than that in adult-onset hallux valgus (28%), and juvenile-onset hallux valgus demonstrated a greater HIA than that displayed by adult-onset hallux valgus (mean ± standard deviation, 12.9 ± 5.7 and 8.3 ± 5.2, respectively). In juvenile-onset valgus, the HIA was negatively correlated with the hallux valgus (r = -0.218, p < 0.001) and intermetatarsal angles (r = -0.143, p = 0.015) and positively correlated with the talonavicular coverage (r = 0.240, p < 0.001) and anteroposterior talocalcaneal angles (r = 0.127, p = 0.008).

Conclusions: Juvenile-onset hallux valgus is associated with more HVI than that in adults. Moreover, forefoot abduction deformity is related to the progression of HVI. These findings highlight the need to consider concomitant HVI when juvenile-onset valgus is encountered.

Level of evidence: Level III, retrospective comparative study.