In order to evaluate the relationship between acetabular and proximal femoral alignment in the initiation and evolution of osteoarthritis of the dysplastic hip, the acetabular and femoral angles were calculated geometrically from radiographs of 62 patients with pre-arthrosis and early osteoarthritis. The sum of the lateral opening angle of the acetabulum and the neck-shaft angle was defined as the lateral instability index (LII), and the sum of the anterior opening angle of the acetabulum and the anteversion angle of the femoral neck as the anterior instability index (AII). These two indices were compared in dysplastic and unaffected hips. A total of 22 unilateral hips with pre-arthrosis were followed for at least 15 years to determine whether the two indices were associated with the progression of osteoarthritis.

The LII of the affected hips (197.4 (sd 6.0)) was significantly greater than that of the unaffected hips (1830 (sd 6.9)). A follow-up study of 22 hips with pre-arthrosis showed that only the LII was associated with progression of the disease, and an LII of 196 was the threshold value for this progression.

Proximal osteotomies for forefoot deformity in patients with rheumatoid arthritis have hitherto not been described. We evaluated combination joint-preserving surgery involving three different proximal osteotomies for such deformities. A total of 30 patients (39 feet) with a mean age of 55.6 years (45 to 67) underwent combined first tarsometatarsal fusion and distal realignment, shortening oblique osteotomies of the bases of the second to fourth metatarsals and a fifth-ray osteotomy.

The mean follow-up was 36 months (24 to 68). The mean foot function index scores for pain, disability and activity subscales were 18, 23, and 16 respectively. The mean Japanese Society for Surgery of the Foot score improved significantly from 52.2 (41 to 68) to 89.6 (78 to 97). Post-operatively, 14 patients had forefoot stiffness, but had no disability. Most patients reported highly satisfactory walking ability. Residual deformity and callosities were absent. The mean hallux valgus and intermetatarsal angles decreased from 47.0° (20° to 67°) to 9.0° (2° to 23°) and from 14.1° (9° to 20°) to 4.6° (1° to 10°), respectively. Four patients had further surgery including removal of hardware in three and a fifth-ray osteotomy in one.

With good peri-operative medical management of rheumatoid arthritis, surgical repositioning of the metatarsophalangeal joint by metatarsal shortening and consequent relaxing of surrounding soft tissues can be successful. In early to intermediate stages of the disease, it can be performed in preference to joint-sacrificing procedures.