Metatarsus Primus Elevatus Resolution After First Metatarsophalangeal Joint Arthroplasty.

BACKGROUND Hallux limitus (HL) is the second-most common pathology associated with the first metatarsophalangeal joint. A common etiology believed to be associated with HL is metatarsus primus elevatus (MPE), although causation has been unsubstantiated by evidence. Historically, correction of MPE is surgically addressed with an osteotomy. However, some believe MPE is a secondary manifestation of HL due to retrograde pressure and lack of dorsiflexion at the first metatarsophalangeal joint. This study sought to determine whether MPE resolves spontaneously after first metatarsophalangeal joint arthroplasty and reinstitution of normal joint dorsiflexion. METHODS Twenty-seven weightbearing lateral radiographs from patients with HL were reviewed before and after nonimplant first metatarsophalangeal joint arthroplasty. Radiographs were taken preoperatively and at postoperative visits 1 (mean, 2 weeks) and 2 (mean, 10 weeks). Measurements included first to second metatarsal elevation, Seiberg Index, first to fifth metatarsal distance, sagittal plane first to second metatarsal angle, Meary's angle, metatarsal declination angle, and hallux equinus angle. RESULTS Statistically significant improvement was seen at both postoperative visits in all of the previously mentioned measurements except first to fifth metatarsal distance, which was reduced but was not statistically significant. CONCLUSIONS Metatarsus primus elevatus was reduced significantly after first metatarsophalangeal joint arthroplasty. Resolution occurred rapidly and was maintained at the final postoperative visit. This could be due to MPE being a manifestation of HL and not a cause. Based on the results of this study, osteotomies may be unnecessary to surgically address MPE because it can spontaneously correct after reinstitution of first metatarsophalangeal joint motion.