Metatarsus adductus (sickle foot): causes, diagnosis and treatment

What is Metatarsus adductus?

With the metatarsus adductus, the forefoot is angled medially (inwards) relative to the mid and rear foot. The rear foot remains neutral or slightly valgus, so the heel does not typically point inwards - this distinguishes the sickle foot from the club foot. Both feet are often affected.

• Frequency peak: newborns and infants
• Often flexible misalignment, passively correctable
• High spontaneous improvement rate in the first year of life
• If the condition is rigid, treatment is required to avoid later symptoms

Anatomy and biomechanics of the forefoot

The forefoot consists of the five metatarsal bones (metatarsalia) and the toes. In the metatarsus adductus, the metatarsals in particular have deviated medially, while the joint axes of the hindfoot are generally aligned normally. A shortened or tense abductor hallucis tendon and soft tissue shortening on the inside of the foot can worsen the deformity.

• Forefoot: Medial adduction
• Hindfoot: mostly neutral, no typical equinus or varus component
• Lateral edge of the foot: crescent-shaped contour
• Soft tissues: relative tightness on the medial side of the foot

Causes and risk factors

In most cases it is a position-related, intrauterine adjustment: the narrow space in the uterus can lead to a temporary misalignment. There are also genetic influences and, rarely, comorbidities.

• Intrauterine positioning (limited space)
• Familial accumulation (connective tissue and skeletal variants)
• Multiple pregnancy, breech presentation
• Muscle or connective tissue tension (e.g. abductor hallucis)
• Associations: rarely with hip dysplasia or other foot deformities; Clarification makes sense

Symptoms, severity and natural history

In infancy, the visible form is in the foreground. Pain is unusual at this point. Later, an inwardly turned gait (intoeing), a tendency to stumble or problems with footwear may occur if the misalignment persists.

• Crescent outer edge, toes pointing inwards
• With flexible shapes, the forefoot can be passively brought into neutral position
• Rigid shapes show clear resistance when attempting to correct them
• Usually spontaneous improvement in the first year of life; persistent rigid deformities are less common

When should you seek medical advice?

• The forefoot cannot be moved towards the neutral position or can only be moved painfully
• Increasing asymmetry or unilateral deformity
• Accompanying abnormalities on the hindfoot (e.g. heel misalignment)
• Gait disorder, frequent stumbling or pain when walking in small children and school children
• Uncertainty as to whether it is a sickle foot or another deformity (e.g. club foot).

Diagnosis in practice

The diagnosis is primarily clinical. We assess the shape of the foot while lying down and standing (depending on age), check mobility and assess the severity. What is crucial is the distinction between flexible and rigid forms as well as differentiation from other deformities.

• Inspection: Course of the lateral edge of the foot, toe position, longitudinal arch of the foot
• Palpation: Tightness of the medial soft tissues (abductor hallucis)
• Mobility test: passive correction of the forefoot
• Foot bisector/heel bisector line for graduation
• Gait analysis in older children (in-toeing, rolling behavior)

Imaging is rarely necessary. If the findings are unclear or there are rigid deformities, an X-ray (if there is sufficient ossification) can be helpful to assess accompanying axes. Ultrasound plays a more important role in accompanying hip examinations in infancy.

Conservative treatment: education, exercises, splints, plaster

The majority of flexible sickle feet improve without invasive measures. The central goal of conservative therapy is to support natural maturation, reduce soft tissue tension and promote good forefoot alignment.

Special “corrective” shoes are rarely effective on their own and are used cautiously today. Sufficiently wide, flexible shoes are only important when the child can walk safely. Barefoot phases on safe surfaces support the foot muscles.

Therapy according to age groups

• Newborns to 3 months: education, positioning, gentle stretching exercises; If there is clear flexibility, an initial wait-and-see approach.
• 3 to 9 months: If there is no improvement or rigidity, discussion about serial casts; accompanying physiotherapy.
• 9 to 18 months: Depending on the course, mobilization may continue; in individual cases, soft splints/night splints.
• From toddler/preschool age: symptom-oriented approach; If there is a persistent misalignment with functional limitations, further diagnosis and adjustment of therapy.

The duration and intensity of treatment depend on the severity, flexibility and development of the child. Each measure is considered individually and evaluated regularly.

Exercises and everyday tips for parents

Exercises should be painless, playful and short. We will show you the handles during the consultation, adapt them to the findings and document the process.

When should surgery be considered?

Surgical procedures are only considered if a relevant, rigid deformity persists despite consistent conservative therapy and leads to functional complaints. That's rare. The decision is made carefully and in an interdisciplinary manner.

• Soft tissue procedures (e.g. abductor hallucis release) with isolated medial soft tissue tightening
• Corrective osteotomies on the metatarsal/cuneiform for severe bony deformity
• Postoperative immobilization, physiotherapy and follow-up checks are required

Every procedure has risks (e.g. wound healing disorders, over/under correction). We provide detailed information and carefully weigh the benefits and risks. A promise of healing cannot be given.

Prognosis and life with sickle foot

The overall prognosis is favorable. A high proportion of flexible sickle feet normalizes over the first few years of life. If the misalignment remains, the range is wide: from clinically inconspicuous findings to children who suffer from a tendency to stumble or pressure points in their shoes. The earlier a rigid form is recognized and treated, the better the functional prospects are.

• High spontaneous remission rate with flexible, mild findings
• Conservative measures are usually effective when indicated and consistently implemented
• Long-term symptoms are rare if timely, adequate action is taken
• Regular follow-up checks ensure the quality of therapy

Differentiation from other foot deformities

• Clubfoot: combination of forefoot adduction, hindfoot varus and equinus; Significantly stiffer, requires a separate treatment concept.
• Arched arches/Pes valgus: Valgic hindfoot, lowered longitudinal arch; no isolated forefoot adduction.
• Hollow foot (Pes cavus): Exaggerated longitudinal arch; other causes and therapy.
• Tarsal Coalition: Bone bridges in the hindfoot/midfoot with limited mobility; often pain in adolescence.
• Skewfoot (Z-foot): Combined deformity with forefoot adduction and hindfoot valgus; differentiated clarification required.

The exact classification is crucial so that therapy goals are realistic and unnecessary measures are avoided.

Your orthopedic consultation in Hamburg

In our practice at Dorotheenstrasse 48, 22301 Hamburg, we combine careful clinical examination with a clear, conservative treatment path. We take time to educate, demonstrate practical exercises and document development at regular intervals.

Our goal is a gentle, comprehensible approach without hasty interventions - always with an eye on the function, development and everyday needs of the family.