外反母趾に対する水平骨切り術後における第1中足骨回内変形の矯正

Abstract

The foot with hallux valgus has pronation deformity in the first ray. To clarify the necessity of a supination osteotomy for pronation correction, we investigated 76 feet in 48 patients with moderate to severe hallux valgus treated with newly devised horizontal osteotomies, which have no potential for pronation correction. Preoperative and postoperative pronation deformities in the first ray were analyzed using radiographies. A mapping study showed that the first metatarsal head was moved in a lateral direction by an average of 16% after the horizontal osteotomy and reducted onto the sesamoids. The most frequent sesamoid position, as classified according to the grading system of Hardy and Clapham, was Ⅶ before surgery and Ⅳ after surgery. Correction of the sesamoid position indicates supination of the proximal phalanx. Concerning the type of hallux pronation using the classification of Okuda et al., angular, intermediate and round shapes of the metatarsal head accounted for 0%, 21%, and 79% before surgery and 59%, 20% and 21% after the surgery. The frequency of the angular shape increased significantly, indicating supination of the first metatarsal head. Even without performing pronation correction at the osteotomy site, consequently correction of the pronation deforrnity of the first metatarsal was observed as well as of the proximal phalanx. Reposition of the sesamoids caused reduction of the first metatarsal head. Our results showed that supination osteotomy is not necessary for correction of pronation deformities in hallux valgus surgery.