Why do lesser toes deviate laterally in hallux valgus? A radiographic study.

BACKGROUND

Hallux valgus foot with laterally deviated lesser toes is a complex condition to treat. Ignoring the laterally deviated lesser toes in hallux valgus might result in unsatisfactory foot shape. Without lateral support of the lesser toes, it might increase the risk of recurrence of hallux valgus. We sought to identify associated radiographic findings in patients where lesser toes follow the great toe in hallux valgus and deviate laterally.

METHODS

The weight-bearing, anteroposterior foot radiographs of 24 female hallux valgus feet with laterally deviated lesser toes (group L), 34 female hallux valgus feet with normal lesser toes (group H), and 43 normal female feet (group N) were selected for the study. A 2-dimensional coordinated system was used to analyze the shapes and angles of these feet by converting each dot made on the radiographs onto X and Y coordinates. Diagrams of the feet in each group were drawn for comparison. The hallux valgus angle, lateral deviation angle of the second toe, intermetatarsal angles, toe length, metatarsal length, and metatarsus adductus were calculated according to the coordinates of the corresponding points.

RESULTS

The mapping showed the bases of the second, third, and fourth toe in group L shifted laterally away from their corresponding metatarsal head (P < .001). The mean 2-3 intermetatarsal angles were: group L, H, N = 7.7 ± 2.6, 4.3 ± 1.9, 4.3 ± 1.3 degrees, respectively (P < .001); mean 3-4 intermetatarsal angles were, for groups L, H, N = 7.3 ± 2.3, 6.1 ± 2.1, 6.3 ± 1.4 degrees, respectively (P < .05). Larger hallux valgus angles (P < .001), more adducted first metatarsal (P < .05), and divergent lateral splaying of the lesser metatarsals (P < .001) were found in group L.

CONCLUSION

Larger 2-3 and 3-4 intermetatarsal angles, larger hallux valgus angle, more adducted first metatarsal, and divergent lateral splaying of the lesser metatarsals were associated with lateral deviation of the lesser toes in hallux valgus.

LEVEL OF EVIDENCE: Level III, comparative study.