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