Metatarsus Adductus

Aka: Metatarsus Adductus, Metatarsus Varus, Forefoot Adduction

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II. Epidemiology

  1. Most common congenital foot deformity
  2. Incidence: 1-2 per 1000 live births
  3. More common in female infants
  4. Left-side more commonly affected than right

III. Cause

  1. In-utero confinement

IV. Pathophysiology

  1. Affects Lisfranc Joint
  2. Adduction of Metatarsal Bones with foot inversion
    1. Results in In-Toeing

V. Types

  1. Metatarsus Varus
    1. Does not spontaneously correct
    2. Fixed deformity
    3. Concurrent tarsometatarsal joint medial subluxation
  2. Metatarsus Adductus
    1. Corrects spontaneously by age 3 months in 90% cases
    2. Flexible deformity
      1. Forefoot can be rotated to neutral position
    3. Associated with medial foot soft tissue contractures

VI. Signs

  1. Images
    1. OrthoPedsFootMTAap.jpg
    2. OrthoPedsFootMTAbottom.jpg
  2. General
    1. Bilateral or Unilateral
    2. Forefoot rotated inwardly
      1. Line bisecting heel pass lateral to third toe
    3. Banana shaped or C-shaped foot
      1. Lateral border of foot convex
      2. Medial border of foot concave
    4. Base of fifth Metatarsal (styloid) prominent
    5. V-Finger Test
      1. Infant's heel in examiner's hand second webspace
        1. Medial foot rests against index finger
        2. Lateral foot rests against middle finger
      2. Foot observed from plantar aspect
      3. Observe for medial deviation of forefoot
        1. Forefoot deviates away from middle finger
    6. Severity
      1. Assess as flexible versus rigid
      2. Heel bisector line drawn from midline heel to forefoot
        1. Normally bisector line intersects the second toe
        2. Mild to moderate cases intersect the third or fourth toe
        3. Severe cases intersect the fourth or fifth toes
  3. Newborn Exam
    1. Heel deviates laterally
      1. Medial malleoli are further from each other
    2. Sole deviates medially (Kidney shaped)
      1. Both feet are inverted (face each other)
    3. Foot easily dorsiflexed (no tight heel cord in contrast to Clubfoot)
    4. Document Severity at Newborn Exam
      1. Based on flexibility of abducting forefoot
      2. Category A: Mild or flexible
      3. Category B: Moderate or fixed
      4. Category C: Severe or rigid
  4. Two month exam: Hold infant in standing position
    1. Accentuates deformity
    2. Estimates degree of deformity

VII. Variations: "Windblown feet"

  1. Both feet point in same direction
  2. Calcaneovalgus foot on one side
  3. Metatarsus Varus on other foot

VIII. Associated deformities

  1. Congenital dislocation of the hip (2-10%)

IX. Differential Diagnosis

  1. See In-Toeing
  2. Excessive Femoral Anteversion (most common)
  3. Medial Tibial Torsion
  4. Clubfoot
    1. Foot also inverted with Forefoot Adduction
    2. Distinguish by limited ankle extension (equinus)

X. Prognosis

  1. Mild or flexible improves during first 3 months of life
    1. Suggests Metatarsus Adductus
    2. Full resolution spontaneously in 85% of cases
  2. Rigid deformity requires treatment
    1. Prevents complications in adults
    2. Adult Bunions and calluses at fifth Metatarsal

XI. Management

  1. Category A: Mild/flexible deformity (Most common)
    1. Parents Stretch child's foot
      1. Firmly stabilize heel
      2. Stretch forefoot laterally (everting foot)
        1. Hold for count of 5 (baby will wince, not cry)
      3. Do for 5 repetitions at each diaper change
  2. Category B: Moderate/fixed deformity
    1. Evaluation by pediatric orthopedics
      1. Evaluation at age 2-4 months
      2. Consider serial corrective casts (or adjustable shoes in pre-walking infants)
        1. Cast every 1-2 weeks for 3-4 casts
      3. Avoid Casting too late (after 4-6 months)
        1. Late Casting is more difficult due to stiff foot
        2. Child also kicks more at older age
    2. May be associated with metatarsus primus varus
      1. Results in extreme adduction of the great toe
      2. May make application of shoes and socks difficult
      3. Surgical release of abductor hallucis
        1. Perform at 6 to 18 months
  3. Category C: Severe/rigid deformity (rare)
    1. Serial casts (or adjustable shoes in pre-walking infants) in first few weeks of life
      1. Takes advantageous of neonates ligament laxity
    2. Corrective Surgery if above not effective (2-4 years old)
      1. Age <7: Soft tissue release tarsometatarsal joint
      2. Age >7: Metatarsal Osteotomy

XII. Prognosis

  1. Spontaneous resolution in 85-90% of cases by age 1 year
  2. Only 4% of cases remain at age 16 years
  3. Often persistent Metatarsus Adductus is asymptomatic, even in adults

XIII. Patient Resources

  1. Hughston Sports Medicine Foundation
    1. http://www.hughston.com/hha/a_13_4_1.htm

XIV. References

  1. Bates (1991) Physical Exam, Lippincott
  2. Hoppenfeld (1976) Exam. Spine Extremities, p.159-60,223
  3. Pediatric Database Homepage by Alan Gandy, MD
    1. http://www.icondata.com/health/pedbase
  4. Churgay (1993) Am Fam Physician 47(4):883 [PubMed]
  5. Gore (2004) Am Fam Physician 69(4):865-72 [PubMed]
  6. Hoffinger (1996) Pediatr Clin North Am 43:1091-111 [PubMed]
  7. Rerucha (2017) Am Fam Physician 96(4): 226-33 [PubMed]
  8. Sass (2003) Am Fam Physician 68(3):461-8 [PubMed]

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