An anatomical basis for the degree of displacement of the distal chevron osteotomy in the treatment of hallux valgus.

The purpose of this study was to define the amount of lateral displacement of the chevron osteotomy to obtain a 50% displacement of the capital fragment. While mathematical analyses exist to predict the degree of correction of the intermetartarsal 1-2 angle with a distal metatarsal osteotomy, no guidelines exist regarding the degree of displacement (translation) that allows sufficient bone contact to enhance union and maintain stability of the osteotomy. We have addressed this concern based on anatomical parameters. The mean metatarsal width of the male specimens measured at 15 mm from the medial osteochondral junction was 15.3 mm (range, 13-18 mm; standard deviation, 1.6). The mean width among the female specimens was 14.5 mm (range, 11-18 mm; standard deviation, 1.6). This difference was statistically significant (P = 0.003). From the results of this study, we have concluded that when using a distal metatarsal osteotomy of the chevron type, in 97.5% of the cases the distal fragment can be translated laterally 6.0 mm in males and 5.0 mm in females to displace it 50% of its diameter.