Hallux Valgus

Epidemiology

  • Women 8:1 men
    • May be more even – women present more due to shoewear
  • Female predispositions:
    1. Joint laxity in females
    2. Shoe wear causing pain
    3. Hormonal influence in women
  • Genetic component in both men & women
  • Hallux valgus does occur in non-shoe-wearing populations
    • Less symptomatic

Aetiology

  • Genetic & Environmental
  • Muscle imbalance or 1st MTP & TMT joint instability:
    • Cerebral Palsy
    • RA
    • Down’s
    • Marfan’s

Pathogenesis

1st Theory

  • Metatarsus Primus Varus causative & MTPJ valgus secondary

2nd Theory – Currently Favored

  • Increased GRF on MTPJ medial aspect pushes PP into valgus
    • In people with pronated feet (common in women)
  • Metatarsus primus varus is actually the secondary deformity
    • In most, the metatarsus varus is fixed and needs an osteotomy

3rd Theory

  • 1st TMTJ hypermobility is the driving force for the problem
    • 1st TMTJ has been found to be hypermobile in many with HV
    • But, this is likely to be a secondary finding in most people
      1. Valgus means 1st ray moves outside control of the plantar fascia
      2. Reduced plantar fascia tension on 1st ray
      3. Destabilises TMTJ - hypermobile

Clinical Evaluation

History

  • What is the main problem – pain or aesthetics?
  • Diabetes, RA, Neurologic disease (CVA), Trauma, Vascular disease
  • Previous interventions

Examination

  • Gait
  • Is valgus correctable passively?
  • MTPJ OA; contracture; congruent joint
  • Site of pain: bunion, joint, lesser toes, plantar aspect
  • Is there pain on MTPJ motion?
  • Plantar callosity distribution – overloading of 2nd MT head
  • Achilles tightness
  • 1st TMTJ hypermobility or pain
  • Lesser toe deformities – fixed or correctable
  • Pulses and neurologic exam
  • ABPI if indicated

Investigations

  • X-Ray:
    • Standing AP (dorso-plantar) and lateral both feet
  • Angles to measure:
    • HVA: Normal = <15°
    • IMA: Normal = <7°
    • HVIA: Normal = <10°
    • PAA: Normal = <10°
    • DMAA: Normal = <10°
  • Other important features to look for:
    • Sesamoid position
    • Joint congruency
    • Joint degeneration
    • Lesser toe subluxation
    • Foot splaying
    • Metatarsus adductus
    • 1st TMT hypermobility:
      • Subluxation of joint
      • Plantar gapping

Classification

  • Mild, Moderate, or Severe
    • Done by HVA and IMA
  • Mild: HVA 15-25°, IMA 7-12°
  • Moderate: HVA 25-40°, IMA 12-25°
  • Severe: HVA >40°, IMA >25°
  • Not that relevant apart from appreciating a severe and a mild deformity
  • Several other factors contribute to ultimate surgical strategy

Relevance of Congruence & Incongruence

  • DMAA is the angle between the line perpendicular to the axis of the 1st MT & the line of the joint
  • In a congruent HV, the DMAA tends to be high and part of the deformity
    • If osteotomy is used to correct the MT without concurrent DMAA procedure, MTPJ may end up incongruent
    • Addition of medial closing wedge osteotomy or incorporation of DMAA correction into the chosen osteotomy is advisable
  • Most HV are incongruent with normal DMAA
    • Therefore, correction with osteotomy makes the joint congruent

Sesamoids in Hallux Valgus

  • Normally centered under MT head over crista, within FHB tendon
  • Medial deviation of 1st MT leads to uncovering of sesamoids
  • Sesamoids initially stay in position - attached to 2nd MTPJ capsule by IML
  • Further uncovering allows GRF to rotate sesamoids laterally and upwards
  • With time, contracture of adductor tendon and lateral capsule occurs
    • Prevents relocation of MT head over sesamoids
  • Sesamoids are within FHB, which attaches to the proximal phalanx base
    • Therefore, rotation of sesamoids = rotation of PP – pronated toe
    • This pulls the abductor plantarward – acts like a flexor
    • Unopposed pull of adductor hallucis exacerbates valgus of PP
    • Medial capsule attenuation occurs

Management

Non-Surgical

  • Initial treatment for all patients if possible
    • High and wide toe-box flat shoes
    • Custom shoes if necessary

Surgical

  • Better results than non-surgical in symptomatic patients
  • No difference if surgery is early or later, so always try non-surgical first

Principles

  • Realign PP with MT head
  • Restore MT head over sesamoids
  • Soft tissue-only procedures tend to fail because of contracture
  • The more proximal the procedure, the more correction is achievable

Soft Tissue Procedures

  • Silver:
    • Simple bunionectomy & capsular reefing
    • Cause of failure: Incomplete correction
  • McBride:
    • Bunionectomy and transfer of adductor from PP to MT neck
    • Can work in early cases of HV with no contracture
    • Cause of failure: Incomplete correction, wrong patient selection, immobile TMTJ

Distal Osteotomies

  • Mitchell:
    • Step-cut lateralisation and shortening of 1st MT
    • 1st osteotomy to employ lateralisation to correct deformity
    • Good long-term results but being superseded by chevron nowadays
  • Chevron Osteotomy:
    • Gold standard currently for mild to moderate HV correction
    • Shouldn’t be done with high IMA (>12°)
    • Maximum translation of 50% to avoid destabilisation
    • Preserve plantar blood supply to MT head
    • V-shaped osteotomy with each limb around 70°
      • Inferior limb more horizontal – perpendicular to GRF
      • Wedge out medially for concurrent DMAA correction
    • Concurrent lateral release to aid correction
    • Fixed with a single screw
    • Advantages:
      • Large surface area and very stable osteotomy
      • GRF passes at the level of osteotomy, so no deforming lever arm
      • Technically simple & reproducible
    • Main complication: AVN of MT head – 2% risk but as high as 20% in one study

Diaphyseal Osteotomies

  • In general, have a large surface area and are perpendicular to WB force
    • Makes them very stable with a high union rate
  • Wilson:
    • Causes shortening of the 1st ray
    • Results in a low-tension correction but:
      • Causes transfer metatarsalgia
    • Out of favor currently
  • Scarf Osteotomy:
    • Very flexible Z osteotomy allowing multiplanar, large-volume correction
    • Combined with separate lateral release:
      • Adductor of proximal phalanx
      • Lateral sesamoid metatarsal ligament
    • Longitudinal incision with an ellipse of capsule excised
    • Plantar blood supply preserved
    • Medial eminence removed
    • Longitudinal cut is in line with the ground, not MT shaft & sloped towards the 5th MT
      • Perpendicular to GRF – increases stability
    • Transverse cuts are parallel to the articular surface
    • Dorsal fragment is translated laterally to correct valgus
    • Rotation possible to correct DMAA
    • Shortening possible to make correction easier
      • Remove some bone from the transverse cut
    • Transfer metatarsalgia not a problem:
      • Obliquity of cut means the head moves plantarward with shortening
    • Long-term comparative results are very good
    • Complications:
      • Troughing is specific to Scarf
        • Dorsal diaphysis rests in the plantar IM canal and rotates the osteotomy – dorsal malunion
        • More common in narrow MT
          • This may preclude reliably performing a Scarf

Proximal Osteotomies

  • Principles:
    • Allow a larger correction with the same degree of displacement
    • Lever arm is longer
    • This is the chief advantage; therefore, they are used for severe deformity
    • Problems:
      • GRF passes close to MTPJ, well away from the osteotomy
      • Proximal osteotomies are vertical on the lateral view
        • Both factors contribute to dorsal malunion
        • May need to limit postoperative WB, unlike chevron/scarf
    • Wedge osteotomies shorten or lengthen the 1st MT
      • Result in transfer metatarsalgia or soft tissue tightness
      • Gold standard: Crescenteric osteotomy – minimal length change
  • Mann Crescenteric Osteotomy:
    • Remove medial eminence distally
    • Make crescenteric proximal osteotomy and fix with a screw
    • Probably the proximal osteotomy of choice
  • Proximal Chevron:
    • Same principle as distal chevron – no shortening
    • A good option but less correction than Mann
  • Ludloff:
    • Long oblique osteotomy from dorsal proximal to plantar distal
    • Osteotomy rotated around a screw, then locked with a second screw
    • No shortening and potentially less dorsal malunion
    • Good option as well

Other Procedures

  • Akin Osteotomy:
    • For residual HV or HV interphalangeus
    • Medial closing wedge through the same incision as a Scarf
    • Stabilised with a staple, wire, or screw
  • Keller Osteotomy:
    • Excision arthroplasty of 1st MT base and medial capsular reefing
    • Preserves some movement in an arthritic joint
    • Possible indications:
      • Salvage of other failed procedures
      • OA of MTPJ
      • Infection, precluding the use of metalwork
      • Diabetics – stiffen up; therefore, Keller may stabilise
    • Main complication: Cock-up toe deformity due to shortening of the phalanx
      • Z-lengthening of EHL may help with this
    • In general, Keller is not a good choice as a primary procedure
    • Salvage of a Keller: MTPJ fusion with a bone block to restore length
  • 1st MTPJ Fusion:
    • Indications:
      • Severe deformities
      • RA
      • Concurrent MTPJ arthritis
      • Salvage for failed or infected surgery
    • Position:
      • 10° of valgus and slight dorsiflexion
      • So that in a plantigrade position, toe pulp is just off the ground
        • Use a flat board intra-operatively
    • Complications:
      • Non-union (5%)
  • Lapidus:
    • Distal medial eminence excision, soft tissue release, and 1st TMTJ fusion
    • Traditionally the choice for hypermobile 1st ray, e.g., in young patients
    • Current thinking: Hypermobile 1st TMTJ is not a primary pathology
      • Secondary to loss of plantar fascia control
    • Therefore, Lapidus should probably be used less
    • High non-union rate: 10-20%
    • Indications currently:
      • Very severe deformity
      • Symptomatic concurrent TMTJ arthritis – rare
      • Salvage for failed distal procedures
      • As part of a flatfoot correction with hallux valgus

Choice of Surgery for the Exam

  • Distal chevron for IMA <12°
  • Scarf for almost all others
    • Advantages of both:
      • Allow early WB
      • Are perpendicular to GRF
      • Can be modified to correct DMAA
  • Add an Akin if HVIA is >10° or there is residual HV
  • Use proximal osteotomies or Lapidus for extreme deformities
    • Beware of their limitations
  • For arthritic 1st MTPJ:
    • If mild and asymptomatic, can continue as normal
    • Otherwise, fuse or perform Keller
    • RA should probably all have fusion

Complications

General

  • Infection, DVT, Nerve injury (dorsal cutaneous)

Specific

  1. AVN
  2. Transfer metatarsalgia
  3. Troughing
  4. Hallux Varus
  5. Recurrence of deformity
  6. Dorsal Malunion

Recurrence

  • 5-20% at 20 years FU

Transfer Metatarsalgia

  • High risk with Wilson’s, Keller’s, or proximal closing wedge

Hallux Varus

  • 1-5% - well tolerated if it does occur

AVN

  • True rate around 1-2%
    • More with distal osteotomy
    • Most asymptomatic

Troughing

  • Specific to Scarf - rotation and dorsal malunion of toe
    • More common in narrow MT

Dorsal Malunion

  • With most vertical proximal osteotomies
    • Causes transfer metatarsalgia – load transfer away from 1st MT head

MTPJ Stiffness

  • From lengthening of 1st MT
    • Lateral release increases stiffness – soft tissue scarring

Juvenile/Adolescent Hallux Valgus

Differences:

  • Family history common
  • Painful bunions often not present
  • Widening of IMA is usually a prominent feature
  • Increased DMAA & congruent Hallux Valgus is more common
  • Hallux Valgus Interphalangeus often present
  • Recurrence rate is higher
  • Soft tissue procedures tend to fail – bony correction required
  • 1st TMTJ more commonly hypermobile - debatable
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