A reappraisal of the relationship between metatarsus adductus and hallux valgus.

BACKGROUND: A causal link between the metatarsus adductus and hallux valgus is not clear. The aim of this study was to investigate the configurations of the metatarsus adductus deformity by radiological measurements and reappraise the relationship between hallux valgus and metatarsus adductus.

METHODS: The first step was evaluation of the relationship between metatarsus adductus and hallux valgus on 143 dorsoplantar weight-bearing radiographs diagnosed as hallux valgus which was also known as bunions. Measurements including the hallux valgus angle (HVA), the intermetatarsal angle (IMA), the Kilmartin angle (KA), the tibial sesamoid position (TSP), and metatarsus adductus angle were taken. The metatarsus adductus angle is defined by Sgarlato's angle (SMA) and Engel's angle (EMA) respectively.

RESULTS: The metatarsus adductus angle positively correlates with the HVA (r = 0.590, P = 0.000) and KA (r = 0.601, P = 0.000), yet negatively correlates with the grade of TSP, (r = -0.348, P = 0.000). Contradiction of diagnosis existed in 22 (22/100) subjects diagnosed as metatarsus adductus by SMA yet normal by EMA. In this group, the correlation between HVA and metatarsus adductus angle was negative (r = -0.472, P = 0.027).

CONCLUSIONS: EMA and SMA defined metatarsus adductus by different deformity apexes. Metatarsus adductus configurations in that the apex of the deformity lay in either the base of metatarsals or tarsus. They respectively correlate positively or negatively to the HVA.