- Discussion:
- great toe provides stability to the medial aspect of the foot thru Windlass mechanism of the
plantar aponeurosis;
- plantar aponeurosis arises adjacent to
tubercle of calcaneus and inserts into the base of the proximal phalanx;
- as body passes over foot, the proximal phalax slides over metatarsal head, which in turn depresses the first metatarsal;
- in
hallux valgus, this stabilization mechanism is disrupted because of lateral subluxation of MP joint;
- windlass mechanism becoems musch less effective, both in depressing metatarsal head and in the wt transfer
to the hallux itself & w/ result of creating transfer
metatarsalgia;
- removal of the base of the proximal phalanx of the hallus (
Keller) disrupts the windlass mechanism and transfers
weight to the second metatarsal head;
- osteotomy that shortens first metatarsal more than 7-10 mm or results in dorsiflexion of first metatarsal
likewise results in decreased wt bearing and hence wt transfer to lateral side of the foot;
