Metatarsus Adductus: Symptoms, Types, Causes and Treatment

Metatarsus adductus is one of the most common congenital foot deformities in children, often recognized by a distinctive inward curvature of the forefoot. While it may appear subtle in infancy, understanding this condition is crucial for parents, clinicians, and anyone interested in pediatric foot health. In this comprehensive article, we’ll explore the telltale symptoms, classification types, underlying causes, and the latest evidence-based treatments for metatarsus adductus—drawing on recent research and clinical guidelines.

Symptoms of Metatarsus Adductus

When it comes to metatarsus adductus, early recognition is key. The symptoms can range from mild and barely noticeable to more pronounced deformities that affect walking and comfort. Understanding these signs helps guide timely assessment and management, which can make a significant difference in outcomes.

Appearance	Severity	Associated Issues	Sources
Curved forefoot	Mild to severe	Metatarsalgia, lesser toe pathology, risk of fifth metatarsal fractures	1,3,5,7
Medial deviation	Flexible or rigid	Hallux valgus, functional discomfort	1,4,7,9
Normal hindfoot	Often present	May coexist with other deformities	1,7

Table 1: Key Symptoms

Recognizing the Symptoms

Metatarsus adductus is most commonly identified by the inward deviation of the forefoot, giving the foot a curved or “banana-shaped” appearance when viewed from above or below. The heel usually remains in a normal position, distinguishing this condition from other foot deformities where the hindfoot is also involved 1,7.

Severity Spectrum

• Mild Cases: The deviation is subtle and often flexible, allowing the foot to be straightened by gentle pressure. These cases may self-correct over time 4,6,7.
• Moderate to Severe Cases: The curve is more pronounced and may be partially or completely rigid, making correction more difficult 4,7,8.
• Associated Symptoms: As children grow, uncorrected metatarsus adductus can contribute to pain (metatarsalgia), lesser toe deformities, and an increased risk of developing hallux valgus (bunion) or stress fractures, especially at the base of the fifth metatarsal 1,3,5,9.

Functional Impact

Children with more severe or rigid deformities may experience difficulty with shoe fitting, altered walking patterns, or discomfort during physical activities. Adults with persistent deformity are at greater risk of secondary foot problems 1,3,9.

Types of Metatarsus Adductus

Not all cases of metatarsus adductus are created equal. The clinical spectrum ranges from fully flexible feet that spontaneously resolve, to rigid deformities requiring intervention. Understanding the classification helps guide treatment and expectations.

Flexibility	Severity	Assessment Method	Sources
Flexible	Mild	Clinical exam, Bleck’s classification, MAS index	4,6,7
Semi-rigid	Moderate	Foot scan, radiographs	2,4,7,8
Rigid	Severe	Objective imaging, resistance to passive correction	2,4,7,8

Table 2: Types of Metatarsus Adductus

Classification by Flexibility

• Flexible Metatarsus Adductus: The most common type, especially in infants. The forefoot can be straightened with gentle pressure. These cases often resolve without treatment 6,7.
• Semi-Rigid Metatarsus Adductus: The forefoot is partially correctable, but some stiffness is present. This type may require conservative interventions such as stretching or corrective bandaging 7,8.
• Rigid Metatarsus Adductus: The forefoot cannot be corrected by hand. These cases are less common and often persist into childhood or adulthood, increasing the risk of complications and possibly requiring surgical intervention 2,4,8.

Severity Grading

• Bleck’s Classification: A widely used clinical system based on the position of the forefoot relative to the heel when viewed from above. Severity ranges from mild (forefoot just medial to the heel border) to severe (forefoot crossing the midline of the heel) 4.
• MAS Index (Metatarsus Adductus Severity Index): An objective measure using foot scans, calculating the ratio of transverse deviation to foot width. This method provides a more quantitative assessment and correlates well with clinical grading 4.

Objective Assessment Tools

• Radiographs: Useful for evaluating bone alignment, especially in older children or when planning surgical correction 2,4.
• Foot Scans: Provide a non-invasive and reproducible means for quantifying severity, recommended as an adjunct to traditional clinical classification 4.

Causes of Metatarsus Adductus

Curious about why metatarsus adductus develops? The origins are multifactorial, involving a combination of genetic, intrauterine, and sometimes postnatal factors. Here’s what research reveals about the underlying causes.

Origin	Mechanism	Risk Factors	Sources
Congenital	Intrauterine positioning	Family history, firstborn status	1,6,7
Structural	Tarsometatarsal joint deviation	Associated with hallux valgus, pes cavus	1,5,9
Mechanical	Abnormal foot loading	Increased risk of fifth metatarsal fracture	3,5

Table 3: Causes of Metatarsus Adductus

Congenital Origins

Metatarsus adductus is most commonly a congenital deformity, meaning it is present at birth. The leading theory is that intrauterine positioning—such as limited space in the womb or breech presentation—exerts pressure on the developing foot, causing the forefoot to curve inward 6,7.

Structural and Anatomical Factors

• Tarsometatarsal Joint Deviation: The deformity primarily affects the tarsometatarsal joint, where the metatarsals meet the midfoot. This leads to medial deviation of the metatarsals and altered forefoot alignment 1,2.
• Medial Deviation and Supination: Along with forefoot adduction, mild supination (outward rolling) of the hindfoot and plantarflexion (downward tilt) of the first ray (first metatarsal and its associated bones) may occur 1.

Mechanical and Genetic Influences

• Abnormal Loading: The adducted forefoot alters weight distribution, increasing stress on the lateral (outer) side of the foot, especially the base of the fifth metatarsal—raising the risk of stress fractures and other overuse injuries 3,5.
• Family History: A genetic predisposition is suggested, particularly when there is a family history of foot deformities 7.
• Association with Other Deformities: Metatarsus adductus often coexists with hallux valgus (bunion) and, less commonly, pes cavus (high-arched foot), which can complicate both diagnosis and treatment 1,5,9.

Treatment of Metatarsus Adductus

The good news: most cases of metatarsus adductus resolve without intervention. For those that don’t, a range of evidence-based options is available—from gentle stretching to specialized surgery. The choice of treatment depends on the age of the patient, severity, and flexibility of the deformity.

Approach	Indication	Effectiveness	Sources
Observation	Flexible, mild cases	High spontaneous resolution	6,7
Stretching, Bandaging	Semi-rigid/mild cases, infants	High if started early, especially in first month	7,8
Serial Casting	Persistent/severe cases	Effective in many, especially under age 1	6,7
Surgery	Rigid, severe, older children/adults	Good outcomes with proper technique	2,9,10

Table 4: Treatment Options

Conservative Management

• Observation: For flexible, mild deformities, no active treatment is needed. Most resolve spontaneously as the child grows and begins to walk 6,7.
• Stretching and Parental Education: Parents are often taught gentle foot stretching exercises to encourage correction during routine care 7.
• Corrective Bandaging: For semi-rigid cases in newborns, starting corrective bandaging within the first month of life has shown high rates of correction, especially in girls. This approach avoids the need for splints or casts in many cases 8.
• Serial Casting: When the deformity is more pronounced or does not improve with stretching, short-term serial casting may be employed—most effective if started before the child is one year old 6,7.

Orthotics and Footwear

• Special Shoes and Orthotics: There is limited evidence supporting the use of corrective footwear or orthotics, but they may be considered in certain cases to maintain correction or improve comfort 7.

Surgical Treatment

Surgery is reserved for severe, rigid, or persistent metatarsus adductus—often after non-surgical options have failed, or in older children and adults.

• Osteotomy Procedures: Surgical correction may involve wedge osteotomies of the cuneiform and cuboid bones, or metatarsal osteotomies, to realign the forefoot. These approaches provide stable fixation and avoid disrupting the growth plate in pediatric patients 2.
• Hallux Valgus Correction: When metatarsus adductus is associated with hallux valgus, specialized surgical approaches may be needed to address both deformities for optimal outcomes 9,10.
• Outcomes: Studies show significant improvement in pain, function, and deformity with appropriate surgical intervention, though recurrence of associated deformities like hallux valgus is higher if metatarsus adductus is not simultaneously addressed 9,10.

Factors Influencing Treatment Success

• Age at Intervention: Early intervention, especially within the first month of life, yields the best outcomes with conservative methods 8.
• Severity and Flexibility: Mild, flexible cases are most likely to resolve without intervention, while rigid or severe deformities require more intensive approaches 6,7,8.
• Associated Deformities: The presence of hallux valgus or other structural abnormalities may necessitate combined or staged procedures for optimal correction 1,9,10.

Conclusion

Metatarsus adductus is a common, usually benign, congenital foot deformity with a spectrum of presentations and outcomes. Early identification and appropriate management can prevent long-term complications and ensure children achieve healthy, pain-free feet.

Key Takeaways:

• Symptoms: Most often presents as a curved forefoot with a normal heel, ranging from mild and flexible to severe and rigid. Associated problems can include pain, toe deformities, and increased fracture risk.
• Types: Classified by flexibility and severity (flexible, semi-rigid, rigid) using clinical and objective methods.
• Causes: Primarily congenital, with contributions from intrauterine positioning, structural alignment, and sometimes genetic factors.
• Treatment: Most flexible cases resolve spontaneously; semi-rigid and rigid forms may require stretching, bandaging, casting, or, rarely, surgery. Early intervention is effective, especially in infants.

By staying informed and seeking timely evaluation, parents and clinicians can work together to ensure the best outcomes for children with metatarsus adductus.