Evaluation of hallux valgus surgery with dynamic foot pressure registration with the Fscan system

Abstract

With the advent of microcomputer technology, in-shoe systems for evaluating dynamic plantar pressure are now available. The use of dynamic registration of hallux valgus patients in floor mounted systems has been shown (Betts, Franks and Duckworth 1991). Twenty-four patients were evaluated preoperatively and 25 months after hallux valgus surgery. Fourteen patients (22 feet) were operated with a chevron osteotomy and 9 (9 feet) with a proximal closing wedge osteotomy. They were evaluated clinically and radiographically. The Fscan system, which uses a thin in-sole to measure plantar pressure was used to evaluate pressure under the five metatarsal heads and the great toe. The plantar pressure measurements of 28 normal feet of 14 healthy volunteers were used for comparison. Nine of the chevron operated patients were completely satisfied with surgery compared to four of the proximal. Shoe fitting was improved for most patients in both groups. A correction of 9° in the hallux valgus angle was achieved in the chevron group, significantly greater than in the proximal group. The pressure under specific areas was related to the sum of all the forefoot areas measured. There was significantly lower pressure under the great toe preoperatively in the hallux valgus patients (57%) compared to the normal controls (64%). Surgery did not normalize this. The pressure under the great toe was still reduced and the pressure under the third metatarsal head was increased postoperatively. Dissatisfied patients had a significantly lower great toe pressure both before and after surgery. Four patients with postoperative metatarsalgia had greater pressure under the lateral metatarsal heads and less pressure under the great toe preoperatively. Postoperatively, the great toe still had reduced pressure. Hallux valgus feet differ from normal feet in having less pressure under the great toe which is not normalized by surgery.