Hallux Valgus

Hallux valgus is a progressive deformity of the first ray with lateral deviation of the hallux, medial deviation and prominence of the first metatarsal head (the bunion), and pronation of the great toe. The prevalence is about 23% in adults aged 18 to 65 and 35% over 65, with a female to male ratio of about 2 to 1.

Causes are multifactorial:

• Footwear with a narrow toe box and a high heel
• Genetic factors (maternal inheritance)
• Pes planus, ligamentous laxity, a tight gastrocnemius
• Inflammatory arthritis (rheumatoid arthritis)
• Neuromuscular disease

Radiographic severity: hallux valgus angle 15 to 20 degrees mild, 20 to 40 moderate, over 40 severe. Intermetatarsal angle 9 to 11 degrees mild, 11 to 16 moderate, over 16 severe. Complications are bunion bursitis, transfer metatarsalgia, overlapping second toe, hammer toe, sesamoid subluxation and arthritis of the first metatarsophalangeal joint.

• A medial prominence, pain and erythema over the bunion, pain in tight shoes
• A pronated hallux, a crossover or hammer second toe, and a callus under the second metatarsal head
• Assess flexibility of the deformity and the first tarsometatarsal joint for hypermobility
• Limited dorsiflexion suggests arthritis
• Red flags: acute hot swollen joint (gout, infection), neuropathy, and a rapid onset in a young adult

• Clinical examination with a standing foot assessment.
• Weight bearing radiographs (anteroposterior, lateral, sesamoid axial view): hallux valgus angle, intermetatarsal angle, distal metatarsal articular angle, sesamoid position, joint congruency and arthritis.
• Inflammatory markers and urate when synovitis is atypical.

Differentials: gout, hallux rigidus, rheumatoid arthritis, septic arthritis, sesamoiditis, bunionette.

Non-operative:

• Wide, deep, low heeled shoes, toe spacers and bunion pads, and custom orthoses for pronation. These relieve pain but do not correct the deformity.
• Diclofenac 1% gel 4 g applied to the bunion three times daily for up to 2 weeks, or ibuprofen 400 mg orally every 8 hours with food for up to 7 days.

Surgery (persistent pain despite 3 to 6 months of care, difficulty with footwear, not for cosmetic indications alone):

• Mild to moderate: distal metatarsal osteotomy (chevron) with a lateral soft tissue release and medial capsule plication.
• Moderate to severe: a proximal metatarsal osteotomy or scarf osteotomy.
• Hypermobile first ray or recurrence: a first tarsometatarsal arthrodesis.
• Severe disease with arthritis or rheumatoid arthritis: arthrodesis of the first metatarsophalangeal joint, fused in 15 degrees of valgus and 15 degrees of dorsiflexion to the floor.
• Minimally invasive techniques with percutaneous osteotomies and screws.
• Cefazolin 2 g IV before incision (3 g if over 120 kg).
• Postoperative: a stiff soled shoe with heel weight bearing for 4 to 6 weeks, elevation and thromboprophylaxis in high risk patients (enoxaparin 40 mg SC daily for 7 to 14 days).

Complications: recurrence (5 to 15%), hallux varus, stiffness, avascular necrosis of the metatarsal head, malunion or nonunion, wound problems and transfer metatarsalgia.

Follow up at 2 weeks, 6 weeks, 3 months and 12 months. Counsel on shoe choice.