Congenital Forefoot Supination and In-Toeing
No, congenital forefoot supination (pes supinatus) does not typically cause in-toeing in pediatric patients. In-toeing is primarily caused by femoral torsion, internal tibial torsion, talar torsion, or metatarsus adductus—not forefoot supination 1.
Understanding the Distinction
Forefoot supination is a simple malposition with excellent prognosis that resolves spontaneously or with minimal orthopedic treatment, without requiring surgery 2. This condition involves the forefoot being positioned in a supinated (turned upward) position but does not create the rotational deformity necessary for in-toeing.
Actual Causes of In-Toeing
The established causes of in-toeing in toddlers include 1:
- Femoral torsion (internal rotation at the hip level)
- Internal tibial torsion (rotation of the tibia bone itself)
- Talar torsion (persistent medial deviation of the talus neck)
- Metatarsus adductus (forefoot adduction, not supination)
Metatarsus adductus, which involves forefoot adduction combined with supination, can cause in-toeing 1, 3. However, this is distinct from isolated forefoot supination (pes supinatus). In true congenital metatarsus varus, the primary deforming factor is contraction of the abductor hallucis muscle, creating both adduction and supination 3.
Clinical Management Implications
Most in-toeing cases (85% when referred) represent normal developmental variation that can be managed with counseling and observation by primary care physicians alone 4. None of the patients in a prospective registry of 143 consecutive in-toeing referrals required casting or surgery 4.
When to Consider Treatment
- For internal tibial or talar torsion: Simple brace treatment is advised for infants up to 18 months if medial deviation exceeds 10 degrees from the mid-sagittal plane 1
- For metatarsus adductus: Serial plaster casts for infants under 8 months with moderate or severe deformity prevent fixed deformity requiring surgery 1
- For femoral torsion: If persistent beyond age 8, surgery becomes the only definitive treatment option 1
Key Clinical Pitfall
Do not confuse pes supinatus (simple forefoot supination) with metatarsus adductus (forefoot adduction with supination). The former is a benign malposition; the latter can cause in-toeing and may require intervention 2, 1. Physical examination should assess the rotational profile including hip rotation, tibial torsion, and foot alignment to identify the true source of in-toeing 4.
Referral to pediatric orthopedics should be reserved for severe cases exceeding 2 standard deviations from the mean or when deformity persists despite appropriate observation periods 4.