- Discussion:
- medial capsule:
- related to repetitive loading of the hallux that leads to attenuation of the medial capsular structures;
- medial migration of first metatarsal:
- first metatarsal head has no musculotendinous attachments;
- head of 1st metatarsal, w/ increased valgus, progressively moves medially off sesamoids, which remain w/ attached to & move w/ proximal phalanx;
- sesamoids:
- because the transverse metatarsal ligament anchors the sesamoids to neck of the 2nd metatarsal, the sesamoids remain in constant position, and the first MT head moves off of them;
- w/ continued hallux valgus progression, sesamoids become displaced laterally until fibular sesamoid becomes located in metatarsal interspace;
- pronation of the hallux:
- during this process there is pronation of the hallux;
- hallux rotates, & callous forms at plantar aspect of its IP joint;
- when hallux assumes a valgus position, the action of the abductor hallucis becomes one of flexion and pronation of the first metatarsal;
- wt bearing under 1st MT head is ineffectual because Windlass Mech is dependent on adequate dorsiflexion of the hallux