Metatarsus adductus (MTA), a common congenital foot deformity present at birth, is characterized by a inward curvature (adduction) of the forefoot at the tarsometatarsal joints, while the hindfoot remains in a normal or slightly neutral position. Often described as a “C-shaped” foot, with a convex lateral border and a concave medial border, it is one of the most frequent pediatric orthopedic conditions, with an estimated incidence of 1-2 per 1,000 live births. The treatment of Metatarsus adductus is a nuanced process that emphasizes a spectrum of care, ranging from simple observation to structured intervention, guided by the severity and rigidity of the deformity.

The cornerstone of effective treatment lies in accurate diagnosis and classification. Metatarsus adductus is not a monolithic entity; its presentation exists on a continuum. Clinicians typically categorize it based on two key parameters: flexibility and severity. Flexibility is the most crucial prognostic factor. A flexible deformity can be manually corrected past the neutral position by the examiner or actively by the infant during stimulation of the peroneal muscles along the outer foot. A partially flexible or “semi-rigid” deformity can be corrected to neutral but not beyond. A rigid deformity resists manual correction entirely, often with a prominent medial crease and a tight abductor hallucis muscle. Severity is often graded by the heel bisector line: in a normal foot, a line extending from the center of the heel passes through the second toe; in mild Metatarsus adductus, it passes through the third toe; in moderate, through the fourth toe; and in severe, through the fifth toe or beyond.

For the vast majority of infants with mild, flexible Metatarsus adductus, the recommended treatment is observation or passive stretching. This approach is grounded in the well-documented natural history of the condition, which demonstrates a high rate of spontaneous resolution. Studies suggest that up to 90% of flexible cases correct on their own without any formal intervention, as the child begins to bear weight and the soft tissues mature. In these scenarios, pediatricians or orthopedists often educate parents on performing gentle, passive stretching exercises during diaper changes. The correct technique involves stabilizing the hindfoot with one hand and using the other to abduct the forefoot, stretching the medial structures. The goal is not forceful correction but consistent, gentle encouragement of the foot into a rectus position. This method is low-risk, cost-effective, and empowers parents to participate in their child’s care. Serial examinations every few months are standard to ensure the deformity is improving as expected.

When the deformity is moderate to severe and semi-rigid, or when flexible deformities show no improvement by the age of 4-6 months, serial casting becomes the gold standard of non-operative treatment. This technique involves applying a series of above-knee (long-leg) plaster or fiberglass casts, changed weekly or bi-weekly. The principle is one of gradual, sustained correction. The casting technique is specific: the hindfoot and ankle are held in a neutral position to prevent unintended correction of a non-existent hindfoot varus, while the forefoot is gently molded into abduction. Each successive cast incorporates a few more degrees of correction, slowly stretching the medial soft-tissue contractures and remodeling the pliable tarsometatarsal joints. The serial casting period typically lasts 6-12 weeks. Success rates for correcting semi-rigid Metatarsus adductus with casting are excellent, often cited between 85-95%. It is most effective when initiated between 6 and 12 months of age, capitalizing on the rapid growth and plasticity of the infant’s foot.

Following successful serial casting, maintenance of correction is essential to prevent recurrence. This is typically achieved with a reverse-last or straight-last shoe or a dynamic splint, such as a Denis Browne bar connecting two shoes set in external rotation. These devices are usually prescribed for full-time wear initially, tapering to nighttime use for several months. Their role is to hold the corrected position as the child begins to cruise and walk, reinforcing the new muscle memory and joint alignment.

The role of surgery in Metatarsus adductus is reserved for the small minority of cases—usually rigid deformities that fail to respond to an adequate trial of serial casting, or for late-presenting, symptomatic cases in older children and adolescents. Surgical intervention is never a first-line treatment in infancy. The procedures are tailored to the patient’s age, the specific anatomical pathology, and the presence of residual deformity.

In the young child (typically 2-4 years old) with a rigid, symptomatic foot, a soft-tissue release may be performed. This involves lengthening or releasing the tight medial structures, most commonly the abductor hallucis tendon and the medial joint capsules of the affected tarsometatarsal joints. This procedure alone can often provide sufficient correction when the bony architecture is still adaptable.

For the older child (over 4-6 years) with a fixed bony deformity, osteotomies (bone cuts) are necessary. These are reconstructive procedures aimed at realigning the foot’s skeletal framework. Common options include a medial cuneiform opening wedge osteotomy or multiple metatarsal osteotomies (the so-called “Bebax” procedure) to derotate and realign the forefoot. In severe, late-presenting cases, a lateral column-shortening procedure, such as a cuboid closing wedge osteotomy, may be combined with medial releases to balance the correction. These surgeries are more complex and require internal fixation with pins or screws, followed by a period of casting and protected weight-bearing. The goal is to create a plantigrade, functional, and pain-free foot.

The treatment of metatarsus adductus exemplifies the principles of progressive, severity-driven orthopedics. It begins with a patient, expectant approach for the majority who will resolve spontaneously, escalates to effective, minimally invasive molding via serial casting for persistent deformities, and reserves surgical reconstruction for the rare, rigid, and recalcitrant cases. This graduated strategy underscores the importance of careful initial assessment—distinguishing flexible from rigid—and continuous monitoring. Ultimately, the management of Metatarsus adductus is highly successful, with the overwhelming majority of children achieving excellent functional and cosmetic outcomes through non-operative means, allowing them to run and play without limitation, their early foot curvature merely a footnote in their developmental history.