Effect of Botulinum Toxin to Hallux Valgus in Addition to Total Contact Insole

Overview

The investigators propose a new therapeutic approach by injecting Botulinum Toxin Type A (BTA) to the oblique and transverse heads of adductor muscle of the great toe. BTA works by binding presynaptically to high-affinity recognition sites on the cholinergic nerve terminals and decrease the release of acetylcholine, causing a neuromuscular blocking effect. The investigators hypothesize that BTA injection may help to decrease the hallux valgus angle by decrease adductor hallucis muscle activation. Thereby enhance the therapeutic result of hallux valgus treated with total contact insole. The outcome measurement may shed light in treating patient with painful hallux valgus and document evidence for plantar pressure changes in acute, sub-acute and chronic stage.

This is a randomized, double-blind, placebo-controlled prospective study to assess the influence and efficacy of intramuscular (IM) Botulinum Toxin Type A (BTA) injection in patients with painful hallux valgus with the use of total contact insole. Fifty feet with painful hallux valgus will be collected. Informed consent is obtained according to the hospital's medical ethics and the human clinical trial committee. The feet will be randomized into 2 groups: Group A (n=25, treatment group) and Group B (n=25, control group). Clinical diagnosis of hallux valgus is made based on observation of great toe lateral deviation. Inclusion criteria were hallux valgus with angle of at least 20°, single or bilateral hallux valgus. To obtain the hallux valgus angle, foot roentgenography in AP and sesamoid views under the weight bearing condition will be obtained. The angle formed by lines drawn to bisect the first metatarsal bone and the proximal phalanx of the great toe will be measured. The exclusion criteria include history of foot operations, rheumatoid and gouty arthritis, and any contraindication to BTA administration. Subjective data such as the Foot Function Index will be collected.