Anatomy of hallux valgus in rheumatoid arthritis: radiographic analysis using a two-dimensional coordinate system

The purpose of this study is to compare the anatomy of rheumatoid hallux valgus with that of idiopathic hallux valgus from the standpoint of joint-preserving surgery.

One hundred forty-eight feet of 81 rheumatoid patients were included. Feet with idiopathic hallux valgus and normal feet were compared as controls. Weight-bearing dorsoplantar radiographs of the feet were taken of each patient. A two-dimensional coordinate system was defined on the radiographic image, and 19 anatomic points of the forefoot were measured.

In rheumatoid hallux valgus, the first metatarsal head shifted medially as hallux valgus angle increased, which was similar to the deformity of idiopathic hallux valgus. Proximal deviation of the tips of the lesser toes, caused by clawing and dislocations of the metatarsophalangeal joints, occurred in rheumatoid hallux valgus. Specifically the tips of the second toes in rheumatoid hallux valgus were located more proximally than those in idiopathic hallux valgus irrespective of the severity of hallux valgus.

Corrective osteotomy of the first metatarsal is a reasonable procedure for rheumatoid hallux valgus. Additionally, correction of the second toe deformity to make a stable lateral support on the hallux may be another important factor for successful joint-preserving surgery.