Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

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Metatarsus Adductus

Basics
Description
  • Metatarsus adductus is a deformity in which the forepart of the foot is adducted or medially deviated; the heel is in neutral or mild valgus position.
  • The most common foot condition seen by those caring for children
  • It appears in the newborn.
  • Classification is based on flexibility: Flexible (correctable with manipulation) or rigid (a continuum)
  • Degree of deformity:
    • Based on heel bisector method: The line bisecting the heel is drawn by visual examination of the foot’s sole; it normally crosses between 2nd and 3rd toes.
      • Mild: Heel bisector crosses the 3rd toe.
      • Moderate: Heel bisector crosses between the 3rd and 4th toes.
      • Severe: Heel bisector crosses between the 4th and 5th toes.
  • Synonyms: Metatarsus varus; Pes varus; Metatarsus internus; Hooked forefoot; Z-foot or C-foot
General Prevention
No effective means of preventing this deformity exist.
Epidemiology
Incidence
  • 1-10 per 1,000 infants
  • Equally distributed between males and females
Risk Factors
  • Family history
  • Hip dysplasia
Genetics
The risk is higher for those with 1st-degree relatives who have metatarsus adductus.
Etiology
  • Unknown
  • No association with birth order, gestational age, or maternal age
  • Most accepted theory: Metatarsus adductus is a possible result of tight intrauterine packing.
Associated Conditions
DDH of the hip occurs in 1-5% of patients with metatarsus adductus.
Diagnosis
Signs and Symptoms
  • Adduction (medial deviation) of the forefoot, with various degrees of supination
    • Concave medial border and convex lateral border of the foot is seen, with prominence at the base of the 5th metatarsal.
  • The heel is in neutral or slightly valgus position, but not in equinus (foot-down).
  • The flexible deformity may persist until 1-2 years of age.
  • Most feet (86% in 1 study) become normal, 10% are mildly adducted, and 4% remain adducted without treatment.
  • In another natural history study, no patients had foot problems when treated with observation alone.
  • A deep medial crease suggests moderate deformity.
Physical Exam
  • Determine the flexibility of the forefoot adduction by trying to correct it.
  • Determine the ankle ROM.
  • The forefoot is deviated medially but flexible.
  • The hindfoot is normal, and the foot may be dorsiflexed to a flat position.
  • Also check the hips for dysplasia.
Tests
Imaging
  • Radiographic evaluation is unnecessary for most patients.
  • If congenital anomalies are suspected or the foot is stiff, AP and lateral views of foot may be obtained.
Pathological Findings
All structures of the foot are normal, except for the forefoot, which is deviated medially.
Differential Diagnosis
  • Clubfoot (heel varus and foot equinus):
    • More rigid
    • Whole foot turned inward
Treatment
General Measures
  • This condition resolves spontaneously in most patients.
  • Parents should be educated about this deformity.
  • Medical treatment:
    • Most children with metatarsus adductus at birth do not require treatment.
    • For severe unresolving deformity, serial manipulation and casting may be offered.
    • The appropriate age at which to start casting is usually 6-12 months.
    • It is appropriate to wait longer if the parents are willing because most feet will improve spontaneously with time.
    • The duration of cast treatment is several months.
    • Children may be placed in straight- or reverse-last shoes for several months after the foot is straightened by cast treatment.
    • Because most of these feet improve spontaneously, early cast treatment before 6 months is not recommended.
Activity
Patients may participate in weightbearing activity as tolerated.
Special Therapy
Physical Therapy
  • Stretching of the foot is recommended for patients with a flexible deformity.
    • Parents may perform this stretching during diaper changes.
Surgery
  • Surgery is an option, but it is rarely indicated.
    • Only for children >4 years old who have residual metatarsus adductus
  • Procedures include the following:
    • Lateral shortening osteotomy
    • Medial cuneiform opening wedge osteotomy
Follow-up
Prognosis
  • >95% patients with mild and moderate deformity have done well in long-term, follow-up studies.
  • It is controversial whether the flexibility of the foot predicts prognosis.
Complications
  • Failure to correct the deformity completely (uncommon)
  • AVN of the cuneiform
Patient Monitoring
  • Frequency of follow-up varies by the individual.
  • It should be more frequent in patients with moderate and severe deformity and in those undergoing treatment.
Miscellaneous
Codes
ICD9-CM
754.53 Metatarsus adductus
Patient Teaching
  • Stress the benign nature of this condition.
  • Even if a mild degree of adduction persists, it has no functionally negative consequences.
FAQ
Q: What problems could arise from untreated metatarsus adductus?
A: In most patients, the adduction resolves if given enough time. The only possible sequelae relate to the fitting of shoes in a minority of patients.

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