The Ludloff metatarsal osteotomy: guidelines for optimal correction based on a geometric analysis conducted on a sawbone model.

Ideally, osteotomy for hallux valgus deformities corrects varus angle and pronation, while minimizing elevation, depression, and shortening. We used a serial linkage tracking device to evaluate five variations of the Ludloff osteotomy, a stable proximal metatarsal osteotomy that incorporates an oblique dorsal to plantar cut and a lateral swing or pivoting correction of the dorsal fragment. A neutral osteotomy (perpendicular to the sagittal plane) yielded the greatest correction (14 degrees) but with shortening (average, 2.85 mm), elevation (average, 1.36 mm), and additional pronation (average, 1.88 degrees). The same osteotomy angled 10 degrees plantarly with 8 degrees of correction produced an average of 1.57 degrees of supination, 1.22 mm of depression and, 0.54 mm of shortening. Additional plantar inclination (20 degrees) and angular correction (16 degrees) yielded increased depression, supination, and shortening. The current findings provide guidelines to achieve the desired correction and rotation and suggest that optimal results can be obtained by performing this osteotomy angled 10 degrees plantarly with a correction of 8 degrees to 16 degrees.