when HV angle >@30 degrees great toe pronates moving abductor hallucis further plantarward leaving the medial capsular ligaments as only medial restraint. Unopposed adductor hallucis pulls toe further into valgus.
Sesamoid bones eventually sublux, once sesamoids are subluxed deformity almost always increases.
Dorsomedial cutaneous nerve of the hallux is a distal branch of the superficial peroneal nerve which supplies sensation to the dorsal and medial half of the hallux and can be injured during chevron bunionectomies (Miller SD, Foot Ankle INt 2001;22:198).
Hallux Valgus Clinical Evaluation
Pain and swelling over the medial eminence mainly associated with shoe wear. May have medial callus.
Evaluate for numbness / tingling over the medial great toe (medial plantar sensory nerve).
Evaluate MTP ROM / stability. Document amount of planterflexion and dorsiflexion.
Great toe pronation. Lesser toe aligment.
1st metatarsocuneiform joint stability.
Foot NV exam.
Evaluate for associated diagnoses which will affect outcome
Hallux Valgus Xray / Diagnositc Tests
Weightbearing AP view, lateral view, standing axial xrays.
Evaluate MTP joint congruity and degree of arthritis.
HV angle = angle between the long axes of the first metatarsal and proximal phalanx; normal<15 degrees.
intermetatarsal (IM) angle=angle between the first and second metatarsals; normal< 9 degrees
Initially treatment: wide-laced (high toe box) shoes; activity modifications
Classification =congruent vs incongruent joint (lateral deviation of the proximal phalanx on the metatarsal head. Sesmoids gradually displace).
Congruent joint: lateral deviation of the articular surgaces of the 1st MTP joint without sesamoid displacement, hallux rotation or sequential progression to the hallux valgus. May be treated with proximal phalangeal osteotomy (Akin Procedure), Chevron osteotomy(Chou, Foot Ankle Int 19:579;1998), or a distal soft tissue procedure.
Incongruent Joint, Moderate deformity (HV <40, IM >13): distal soft tissue procedure with proximal metatarsal osteotomy, Modified Rotational Scarf Osteotomy . If there is hypermobility of the metatarso-tarsal (cuneiform) joint, metatarso-cuneiform arthrodesis with a distal soft tissue procedure is used. Lapidus procedure=1stmetatarsocuneiform arthrodesis(Sangeorzan Foot ankle 9:262;1989)
Incongruent Joint, Severe deformity (HV <40, IM >13): 1st MTP Arthrodesis 28750 is used in severe deformities, particularly in older patients or patients with rheumatoid arthritis, spasticity, or arthrosis. Arthrodesis--Optimal arthrodesis angle = 25-30 degrees, metatarsal inclination angle = 25-30 degrees. Sagittal plane position should be checked intraoperatively and the proximal phalanx should clear the table by 5-10mm with simulated weightbearing.
Treatments that have fallen out of favor include metatarsophalangeal resection arthroplasty and removal of the medial eminence (Keller procedure), or simply excision of the medial eminence with plication of the capsule (bunionectomy). The former results in destabilization of the first MTP joint and subsequent metatarsalgia and deformity, while the latter often fails to correct the deformity
Mitchell osteotomy=extracapsular; medial eminence excised, osteotomy 2cm proximal to medial border of articular surface; osteotomy laterally displaced.
Hallux Valgus Associated Injuries / Differential Diagnosis
spasticity--The only way to adequately eliminate spastic deforming forces is with an arthrodesis of the MTP joint. Any other procedure will most likely lead to a high incidence of either hallux varus or recurrent hallux valgus.
Hallux Valgus Interphalangeus: lateral deviation of the great toe at the interphalangeal joint.
Hallux Valgus Complications
Distal chevron osteotomy with soft tissue release complications = incomplete correction and avascular necrosis (1 – 2%).
Distal soft tissue realignment only complications = recurrence of deformity, inadequate lateral release, and hallux varus.
Aken procedure complications = increase in the hallux valgus deformity.
Proximal first metatarsal osteotomy complications = hallux varus and shortening.
Resection of both sesmoids risk development of cock-up toe deformity
Dorsomedial cutaneous nerve of the hallux neuroma (Miller SD, Foot Ankle INt 2001;22:198).
Osteonecrosis of the metatarsal head. Shariff R, Attar F, Osarumwene D, Siddique R, Attar GD. The risk of avascular necrosis following chevron osteotomy: a prospective study using bone scintigraphy. Acta Orthop Belg. 2009 Apr;75(2):234-8. Easley ME, Kelly IP. Avascular necrosis of the hallux metatarsal head. Foot Ankle Clin. 2000 Sep;5(3):591-608.
Hallux Valgus Follow-up Care
Hallux Valgus Review References
Mann, Disorders of the first metatarsophalangeal joint, JAAOS, 3(1): 34-43, 1995
Coughlin MJ: Roger A. Mann Award. Juvenile hallux valgus: Etiology and treatment. Foot Ankle Int 1995;16:682-697.
Zimmer TJ, Johnson KA, Klassen RA: Treatment of hallux valgus in adolescents by the chevron osteotomy. Foot Ankle 1989;9:190-193.