Background Metatarsus primus elevatus involves dorsal elevation of the first metatarsal relative to the lesser metatarsals. The role of metatarsus primus elevatus in rheumatoid forefoot deformity is yet to be elucidated. We hypothesize that metatarsus primus elevatus can be attributed to a different pathomechanism than typical rheumatoid forefoot deformities such as hallux valgus, splay foot, and flat foot.
Objectives To clarify the radiographic characteristics of metatarsus primus elevatus in patients with rheumatoid forefoot deformities.
Methods We retrospectively reviewed standing anteroposterior and lateral radiographs of 51 feet (37 patients; mean age 65.7±7.1 years) before toeplasty due to metatarsalgia at our hospital. The elevation of the first metatarsal relative to the second metatarsal (MPE), the hallux valgus angle (HVA), the intermetatarsal angle (IMA), talar pitch, and calcaneal pitch were measured. For statistical analyses, the Mann-Whitney U test was used.
Results Median MPE was 1.7 mm (interquartile range: 0.7–4.5 mm). We compared the group with MPE >5 mm (N=12 feet) to the group with MPE ≤5 mm (N=39 feet). The group with higher MPE was significantly younger (p=0.011). There was no significant difference in HVA between the two groups (p=0.068), although IMA was significantly smaller in the group with higher MPE (p=0.033). In the group with higher MPE, calcaneal pitch was greater (p<0.001) and talar pitch was smaller (p=0.016).
Conclusions In patients with metatarsus primus elevatus, other rheumatoid forefoot deformities such as spray foot and flat foot were not observed. There was a wide range of hallux valgus severity. Metatarsus primus elevatus may be attributed to greater hindfoot calcaneal pitch.
Disclosure of Interest None declared