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Windlass Mechanism



- 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