A RADIOGRAPHIC EVALUATION OF THE SCARF OSTEOTOMY FOR THE CORRECTION OF HALLUX VALGUS

The SCARF osteotomy is a three dimentional osteotomy for hallux valgus. It combines a lateral release of the adductor hallucis with a lateral and plantar displacement of the first metatarsal. The osteotomy is ‘z’ shaped in the lateral view and displacement of the distal fragment is followed by internal fixation. In this study we set out to determine whether the SCARF osteotomy was an effective method in the correction of moderate to severe hallux valgus deformity. A prospective radiographic study was performed on 22 cases of SCARF osteotomy with an average age of 52 years (range 25–78). Standardised weight bearing anterior-posterior radiographs were taken preoperatively and at six months post operatively. The American Foot and Ankle Society guidelines were used for all measurements. Measurements were made using overlay acetate sheets to minimise inter and intra observer error. These were compared to determine changes in the intermetatarsal angle (IMA), hallux valgus angle (HVA), distal metatarsal articular angle (DMAA) and joint congruency angle (JCA). Correction of sesamoid position and metatarsal length changes were also assessed. The results showed a median reduction of IMA of 6 degrees, HVA of 16 degrees, DMAA of 6 degrees and an improvement in JCA of 11 degrees. Improvement of the lateral sesamoid displacement from beneath the first metatarsal head was seen postoperatively. Metatarsal length was assessed by comparing the ratio of the length of the first to second metatarsal pre and post operatively. No shortening was found. There was no incidence of avascular necrosis or non-union. This study indicates that the SCARF osteotomy produces effective radiological correction of hallux valgus where there is moderate to high degree of deformity. It also improves sesamoid displacement and avoids shortening of the first metatarsal.