Insertion of the abductor hallucis muscle in feet with and without hallux valgus.

Textbooks of human anatomy present different opinions on the insertion of the abductor hallucis muscle which is concerned in etiology as well as in therapy of hallux valgus. In plastic and reconstructive surgery the muscle is taken as a graft for flap-surgery. In this study 109 feet (58 right, 51 left) were examined, 18 of these with clinical hallux valgus. The tendon of the muscle may attach to the tendon of the medial head of the short flexor hallucis muscle where a subtendineous bursa can be found. At the head of the first metatarsal bone the joint capsule is reinforced by fibres arising from the medial sesamoid bone which may be called "medial sesamoidal ligament." The tendon passes the first metatarsophalangeal joint plantarily to its transverse axis. Three types of insertion could be distinguished: type A, insertion at the proximal phalanx (N = 42); type B, insertion at the medial sesamoid ligament and at the medial sesamoid bone (N = 65); type C, insertion at the medial sesamoid bone (N = 2). In all types superficial fibres of the tendon extended to the medial and plantar sides of the base of the proximal phalanx, running in a plantar to dorsal direction. Statistical analysis exposed neither significant differences between both sides nor significant difference between normal feet and feet with hallux valgus. Therefore, a specific pattern of insertion of the abductor hallucis muscle in hallux valgus cannot be stated.