Metatarsus primus elevatus in hallux rigidus: fact or fiction?

Two hundred seventy-five lateral weightbearing radiographs of isolated pathology were reviewed and stratified into hallux rigidus (n = 100), hallux valgus (n = 75), plantar fasciitis (n = 50), and Morton's neuroma (n = 50) groups. The patient population consisted of healthy individuals with no history of foot trauma or surgery. The first to second metatarsal head elevation, Seiberg index, first to second sagittal intermetatarsal angle, first to fifth metatarsal head distance, and hallux equinus angle were measured in each population. Statistically significant differences were found between the hallux valgus, plantar fasciitis, and Morton's neuroma populations and the hallux rigidus population, which showed greater elevation of the first metatarsal relative to the second for each radiographic measurement technique. In the hallux rigidus population, there was a statistically significant difference between grade II and grades I and III regarding the first to fifth metatarsal head distance (greater in grade II) and the hallux equinus angle (lower in grade II). A review of the literature and comparison with historical controls reveals that metatarsus primus elevatus exists in hallux rigidus and is greater than that found in hallux valgus, plantar fasciitis, and Morton's neuroma groups.