Principles of first metatarsal osteotomies.

Summarizing all the data while choosing the suitable procedure for hallux valgus deformity leads to classification of 3 main categories, which are based on the intermetatarsal angle (Table 1). Mild deformity has less than 15 degrees intermetatarsal angle, intermediate deformity has 15 degrees to 20 degrees intermetatarsal angle, and severe deformity has more than 20 degrees [table: see text] intermetatarsal angle. Every category may be divided further into low degree of DMAA (8 degrees) or high degree of DMAA (> 15 degrees). When choosing the correct procedure, the length of the first metatarsal has to be considered. In short first metatarsals, base angular osteotomies lead to further shortening of the metatarsal. Displacement osteotomies are preferred. In mild deformity, a distal osteotomy can be performed. If a mild deformity has a high DMAA, it can be corrected by a distal rotated chevron osteotomy. Intermediate deformity with a normal DMAA can be corrected by displacement osteotomies, and high DMAA can be corrected by rotated scarf of double osteotomy, which includes a base osteotomy to correct the intermetatarsal angle and a distal osteotomy, such as Riverdin, to correct the DMAA. Severe deformity can be corrected only by angular osteotomies. Inherently, these osteotomies increase the DMAA; they can be performed only in normal DMAA. Only a base angular osteotomy and distal rotation osteotomy can correct high levels of DMAA in severe intermetatarsal angles.