Insertion of the tendon of the tibialis anterior muscle in feet with and without hallux valgus

The insertion of the tendon of the tibialis anterior muscle may be related to pathologic changes of the foot and, in particular, hallux valgus. Morphologic data should enable evaluation of such a relationship and perhaps offer a basis for improved therapy. One hundred fifty-six embalmed feet, including 27 with hallux valgus, were examined. The tendon of the tibialis anterior muscle was dissected and measurements were made, including the width of the insertion on the first metatarsal and medial cuneiform. Distal-superficial and proximal-deep slips of the tendon twisted around each other. Two specimens presented with an insertion only on the medial cuneiform; in two other cases the insertion was limited to the first metatarsal; in one case the tendon inserted into the navicular and the medial cuneiform; in all other cases, the tendon inserted into the medial cuneiform and first metatarsal. The insertion was mainly located along the plantar margin of the medial side of the foot; some of the proximal-deep fibers also passed onto the plantar surface. Fibers inserting on the first metatarsal bone can outwardly rotate the first ray, which is opposite to the inward rotation of the first ray in hallux valgus. In all feet with hallux valgus these fibers were present. Therefore, it is unlikely that this deformity develops because of a specific type of insertion of the tendon of the tibialis anterior muscle, and any therapeutic approach altering the attachment of the tibialis anterior tendon would cause no biomechanical improvement.