Effect of Mechanical Axis Correction on Outcomes of Hallux Valgus Surgery

A new method of mechanical axis planning has recently been suggested to aid in corrective surgery for hallux valgus (HV) deformity, which aims to identify the ideal position for the first metatarsal after correction. We investigated the influence of the mechanical axis angle (MAA) correction on the outcomes of corrective HV surgery. We reviewed 50 radiographs to identify the "normal" MAA range within the population. We also reviewed the medical records of 100 patients who had undergone scarf osteotomy at our institution from January 2011 to December 2013. These patients were segregated into 2 groups according to their postoperative MAA: those within the normal range (normal group) and those outside this range (outlier group). We compared the pre- and postoperative functional scores between the 2 groups using statistical analysis. The normal MAA range within our population was 12.5° ± 0.8° (range 11.0° to 14.3°). We found that the physical component summary score of the short-form 36-item health survey was significantly poorer for the outlier group at 6 and 24 months postoperatively compared with the normal group, although the other postoperative scores were comparable. Surgical correction of the MAA to the normal range of the patient population can be recommended because it provides improved quality of life. However, further studies are required to investigate the influence of MAA planning on other standardized foot and ankle scores.