Definition:
Aka bunion, is lateral deviation of the proximal phalanx with subsequent medially directed pressure against the first metatarsal head
o Congruent = no MTP joint subluxation
o Incongruent = lateral subluxation of proximal phalanx on the metatarsal head
Description:
o Weakening of first metatarsophalangeal (MTP) medial joint capsule, contracture of lateral joint capsule
o Eventual sesamoid subluxation laterally
o Extensor hallucis longus and Flexor hallucis longus tendons deviate laterally, increasing deformity.
Etiology:
o Women:men = 10:1
o Tight or pointed shoes – incidence lower in populations that do not wear shoes
o Congenital predisposition
o Severe flatfoot deformity
o Tight Achilles tendon
o Hypermobility of first metatarsocuneiform joint
o Rheumatoid Arthritis
Text Box: Angles:
Hallux Valgus Angle (HV) = formed by lines that longitudinally bisect proximal phalanx and 1st metatarsal (52°)
Intermetatarsal Angle (IM) = intersection of lines bisecting 1st and 2nd metatarsal shafts (20°)
Symptoms:
o Medial eminence pain
o Metatarsalgia (first or lesser metatarsal head pain)
o Impingement on second toe
o Inability to wear shoes
Imaging:
o Weight-bearing anteroposterior, lateral and oblique radiographs
Treatment Considerations:
o Symptoms severity
o Degeneration of 1st MTP joint
o Flexibility of 1st metatarsocuneiform joint
o HV and IM angles
o Congruent or incongruent 1st MTP joint
o Age
Treatment Options:
o Conservative, non-operative
– Wide shoes
– Pads under metatarsal heads to alleviate pressure
o Distal soft-tissue procedure = opening lateral joint capsule, tightening medial joint capsule and resection medial eminence, for mild deformity (HV<30, IM<13)
o Distal soft tissue procedure with proximal metatarsal osteotomy (HV up to 50, IM up to 25)
o Chevron (Mitchell) procedure = distal metatarsal osteotomy with laterally translation of medial head, for mild deformity
o Akin Procedure = see image
o Keller Procedure = see image
o Lapidus Procedure = (see image, right) for severe deformity with hypermobile 1st metatarsocuneiform joint, involves distal soft-tissue procedure and 1st metatarsocuneiform arthrodesis (fusion)
o Many other procedures described
Text Box: Akin Procedure(above): medial closing wedge osteotomy at base of proximal phalanx. For mild deformities with congruent jointsText Box: Keller Procedure (right): removal of base of proximal phalanx and medial eminence resection. For elderly, inactive patients only