Evaluation of the anterior and middle talocalcaneal articular facets and the Evans osteotomy.

The purpose of this study was to determine the occurrence of discrete anterior and middle talocalcaneal facets and the distance of these facets from the anterior border of the calcaneus as it relates to the Evans osteotomy. Seven hundred sixty-eight calcanei were examined from the human osteology archive at the Cleveland Museum of Natural History. Measurements taken included: 1) distance from the proximal border of the anterior facet to the anterior border of the calcaneus (DTAF), 2) distance from the distal border of the middle facet to the anterior border of the calcaneus (DTMF), and 3) width of facet separation (WFS). The results revealed that 310 of 755 (41.06%) had discrete anterior and middle facets and 423 of 755 (56.03%) had a conjoined facet. In those with discrete facets, the mean DTAF, DTMF, and WFS were 11.04 mm, 15.47 mm, and 3.85 mm, respectively. In those with discrete facets, an osteotomy begun between 11.5 mm and 15 mm from the calcaneocuboid joint should pass between the anterior and middle facets and avoid damaging these articular surfaces. This information may aid the foot and ankle surgeon in patient selection and in attaining optimal surgical outcome for the Evans lateral column lengthening procedure.