Hallux Valgus

 

Introduction

• Hallux valgus is a complex tri-planar cascade deformity of the 1^st ray
• Global prevalence up to 23% in 18-65y; 35% in >65y

 

Risk factors

Intrinsic

• Genetic predisposition; 70% of cases have positive family history
• Hypermobility, connective tissue disorders
• Rheumatoid arthritis
• Pes planus (complex role)
• Neurological foot e.g. CP
• 2^nd toe deformity

Extrinsic

• High heel shoes
• Narrow toe box

 

Types

• Adult onset
• Adolescent & juvenile
  • often bilateral and familial
  • pain usually not primary complaint
  • varus of first MT with widened IMA usually present
  • DMAA usually increased
  • often associated with pes planus

 

​Pathogenesis

In a normal foot the extensor and flexor tendons are slightly lateral to the centre. This is compensated by other muscles and ligaments in the foot; however, the overall forces remain balanced. This equilibrium is sensitive to internal and external influences and, when disrupted, can lead to hallux valgus.

Pathoanatomy

• valgus deviation of phalanx promotes varus position of metatarsal
• the metatarsal head displaces medially, leaving the sesamoid complex laterally translated relative to the metatarsal head
• sesamoids remain within the respective head of the flexor hallucis brevis tendon and are attached to the base of the proximal phalanx via the sesamoid-phalangeal ligament
• this lateral displacement can lead to transfer metatarsalgia due to shift in weight-bearing
• medial MTP joint capsule becomes stretched and attenuated while the lateral capsule becomes contracted.
• adductor tendon becomes deforming force
  • inserts on fibular sesamoid and lateral aspect of proximal phalanx
• lateral deviation of EHL/FHL further contribute to deformity
• plantar and lateral migration of the abductor hallucis causes muscle to plantar flex and pronate phalanx
• windlass mechanism becomes less effective leading to transfer metatarsalgia

 

Clinical Presentation

• 80% - restriction in footwear
• 70% - pain over the medial eminence
• 60% - cosmetic concerns
• 40% - pain underneath the second metatarsal head
• Pain over dorso-medial exostosis due to pressure on dorsal cutaneous nerve
• Transfer metalasalgia
• Lesser toe deformitites
• 1^st MPTJ degeneration

 

Conservative treatment

​Always offer non-operative management first

• Footwear:
  • accommodative
  • soft material
  • extra width or depth of toe box
  • medial arch support if associated pes planus
  • custom, accommodative insoles to offload lesser MT heads
  • lesser toe sleeves

 

Surgical treatment

 

• >150 procedures described
• little evidence comparing different procedures
• ​85% satisfied, 10% less satisfied, 5% poor outcome
• performed via combination of soft tissue release and bony correction(s)

The principal contraindication to surgery is arterial occlusive disease.

 

Aim of surgery

• Clinically: well-aligned, pain-free, functional big toe
• Radiologically: correction of HVA/IMA/DMAA, congruent joint, sesamoids under M1 head

 

Soft Tissue Release

• ​sesamoid suspensory ligament
• +/- adductor hallucis tendon in severe deformities
• maintain lateral collateral ligament to prevent hallux varus
• can be performed:
  • via original incision ‘over the top’ of the M1 head
  • via original incision through the Scarf osteotomy
  • via a separate dorsal incision

​

Bony correction

The ideal osteotomy should:

• be technically easy to perform and reproducible
• be stable and not displace
• maintain the length of the 1^st MT to prevent transfer metatarsalgia
• avoid dorsiflexion of the MT head
• be versatile to correct any angle necessary (HVA, IMA, DMAA)
• preserve blood supply to avoid avascular necrosis of the MT head
• have a low recurrence rate

Based on the severity of deformity typical practice in the UK involves:

• Mild: chevron or short scarf osteotomy +/- Akin
• Moderate: scarf +/- Akin osteotomies
• Severe:
  • proximal metatarsal osteotomy +/- Akin
  • corrective fusion of the 1st MTP joint
  • corrective fusion of the 1st TMT joint +/- Akin

 

Recurrence rates can be as high as 50%, although often quoted as 5-10%

Causes of recurrent deformity include:

• patient-related factors:
  • e.g. Parkinson’s disease, high BMI, gout, hypermobility
  • anatomic predisposition (e.g. pes planovalgus, joint congruence, pronated MT head)
  • poor post-operative compliance
• Surgical factors include:
  • procedural choice
  • surgical / technical expertise

 

Scarf Osteotomy

• popularised by Barouk, technically challenging
• highly versatile
• z-shaped, meta-diaphyseal osteotomy of the first metatarsal
• shape and length of the osteotomy offers good stability – usually fixed with two screws
• allows lateralisation of the plantar head-shaft limb to reduce the IMA
• maintains or improves joint congruence and motion of the first MTP joint
• permits elevation /  plantarisation of the metatarsal head, lengthening / shortening, and transverse plane rotation for correcting an increased DMAA

 

​Akin osteotomy

• commonly performed, usually as an adjunct procedure
• helps to ‘fine-tune’ the final correction
• multiple fixation options: suture, wire, screw, staple (most favoured)

​Scarf + Akin osteotomies with distal soft tissue release has become the preferred option for hallux valgus correction in the UK.