Metatarsus Adductus
Metatarsus Adductus
Metatarsus adductus is a common congenital foot deformity characterized by medial deviation of the forefoot at the tarsometatarsal joints, while the hindfoot remains in a neutral position. It occurs in approximately 1 in 1000 live births.
Key Characteristics:
- Medial deviation of metatarsals relative to hindfoot
- Normal hindfoot alignment
- C-shaped lateral border of foot
- Normal arch height
- Normal ankle position
Epidemiology
- Affects 1-2 per 1000 live births
- More common in firstborn children
- Bilateral in 50% of cases
- Associated with intrauterine positioning
- Higher incidence in twins
Etiology
- Intrinsic Factors:
- Genetic predisposition
- Family history
- Muscle imbalance
- Extrinsic Factors:
- Intrauterine positioning
- Oligohydramnios
- Multiple gestation
- Large fetus
Clinical Presentation
- Physical Examination:
- Bean-shaped foot appearance
- Convex lateral border
- Prominent base of 5th metatarsal
- Normal hindfoot alignment
- Preserved ankle motion
- Associated Findings:
- Hip dysplasia (5-10% association)
- Developmental torticollis
- Plagiocephaly
Classification (Bleck's Classification)
- Mild:
- Forefoot adduction <20°
- Flexible deformity
- Heel-bisector line passes through 3rd toe
- Moderate:
- Forefoot adduction 20-30°
- Partially flexible
- Heel-bisector line passes through 4th toe
- Severe:
- Forefoot adduction >30°
- Rigid deformity
- Heel-bisector line passes through 5th toe or lateral to foot
Diagnostic Approach
- Physical Examination Tests:
- Heel bisector line assessment
- Forefoot flexibility test
- Great toe extension test
- Bean-shaped foot appearance
- Imaging Studies:
- Radiographs rarely needed in infants
- Weight-bearing AP and lateral views in older children
- Measure talus-first metatarsal angle
- Assess tarsometatarsal alignment
Differential Diagnosis
- Talipes Equinovarus (Clubfoot)
- Skewfoot
- Congenital vertical talus
- Calcaneovalgus foot
Clinical Assessment Tools
- Heel Bisector Method:
- Draw line through center of heel
- Extend through 2nd web space
- Assess relationship to toes
- Flexibility Assessment:
- Manual correction of forefoot
- Passive abduction range
- Assessment of midfoot mobility
Treatment Approach
- Observation:
- Mild flexible cases
- Regular monitoring of progression
- Spontaneous resolution in 80-90% of cases
- Conservative Treatment:
- Stretching exercises
- Passive forefoot abduction
- Parent education
- Regular monitoring
- Serial casting
- Weekly cast changes
- 3-8 casts typically needed
- Best results before 8 months of age
- Orthotic devices
- Reverse-last shoes
- Night splints
- Custom orthotics for older children
- Stretching exercises
Surgical Management
Rarely needed (<5% of cases), but may be considered for:
- Severe rigid deformity
- Failed conservative treatment
- Age >4 years with significant deformity
- Procedures may include:
- Capsulotomy of medial tarsometatarsal joints
- Abduction osteotomy of cuneiforms
- Lateral column shortening
Prognosis and Follow-up
- Excellent with early treatment
- 90% resolution with conservative management
- Regular monitoring until walking age
- Long-term follow-up for severe cases
- Monitor for developmental hip dysplasia
