Crescentic osteotomy for hallux valgus: a biomechanical study of variables affecting the final position of the first...

The position of the first metatarsal following a crescentic osteotomy for hallux valgus is a function of the size of the saw cut and orientation of the osteotomy. This study reports the effect of these variables, recommended technique, and potential pitfalls when using the crescent osteotomy. Using molded polyurethane foam metatarsals and a precision drill press which controlled the saw cuts, the following variables were studied: (1) orientation of the saw cut to the metatarsal, (2) the saw size (diameter of the saw relative to the shaft width of the osteotomy site), and (3) the direction toward which the crescent faces (proximal/distal). Best correction can be obtained if the saw diameter is larger than the diameter of the osteotomy site (allowing a greater degree of correction before impingement), the saw tip is tilted slightly toward the sesamoids (which ensures that the metatarsal does not rotate medially with correction), and the saw is rotated laterally to cause slight declination of the toe.