Metatarsus adductus

Metatarsus adductus is a common foot deformity noted at birth that causes the front half of the foot or forefoot, to curve inwards rather than straight ahead and occasionally the toes spread widely. The bones in the front half of the foot bend or turn in toward the side of the big toe. Metatarsus adductus is a fairly common deformity affecting the feet of newborns and young children. Metatarsus adductus is one of the reasons why people develop “in-toeing.”

Metatarsus adductus may also be referred to as “flexible” (the foot can be straightened to a degree by hand) or “nonflexible” (the foot cannot be straightened by hand). Metatarsus varus is another term usually refers to the fixed form of metatarsus adductus that requires treatment. When this is the case, your child may require leg casts, splints or braces to straighten the feet.

The cause of metatarsus adductus is not always clear, however it is thought to be related to the way the child is ‘tucked up’ in the womb. The feet will usually straighten within a year or two of birth, and the deformity usually has little effect on walking or crawling.

Babies born with metatarsus adductus rarely need treatment as they grow. They may, however, be at increased risk for developmental dysplasia of the hip also called slipped capital femoral epiphysis (SFCE), a condition of the hip joint in which the top of the thigh (femur) slips in and out of its socket, because the socket is too shallow to keep the joint intact.

Metatarsus adductus causes

The cause of metatarsus adductus is not known. It occurs in approximately 1 to 2 per 1,000 live births and is more common in first born children.

Metatarsus adductus is thought to be caused by the infant’s position inside the womb. Risks may include:

• The baby’s bottom was pointed down in the womb (breech position).
• The mother had a condition called oligohydramnios, in which she did not produce enough amniotic fluid.

There may also be a family history of the condition.

Metatarsus adductus symptoms

The front of the foot is bent or angled in toward the middle of the foot. The back of the foot and the ankles are normal. About one half of children with metatarsus adductus have these changes in both feet.

Newborns with metatarsus adductus may also have a problem called developmental dysplasia of the hip (slipped capital femoral epiphysis). This allows the thigh bone slips out of the hip socket.

(Club foot is a different problem. The foot is pointed down and the ankle is turned in.)

Metatarsus adductus diagnosis

A doctor makes the diagnosis of metatarsus adductus with a physical examination. During the examination, the doctor will obtain a complete birth history of the child and ask if other family members were known to have metatarsus adductus.

Diagnostic procedures are not usually necessary to evaluate metatarsus adductus. However, X-rays (a diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film) of the feet are often done in the case of nonflexible metatarsus adductus.

An infant with metatarsus adductus has a high arch and the big toe has a wide separation from the second toe and deviates inward. Flexible metatarsus adductus is diagnosed if the heel and forefoot can be aligned with each other with gentle pressure on the forefoot while holding the heel steady. This technique is known as passive manipulation.

If the forefoot is more difficult to align with the heel, it is considered a nonflexible, or stiff foot.

Metatarsus adductus treatment

Treatment is rarely needed for metatarsus adductus. In most children, the problem corrects itself as they use their feet normally.

In cases where treatment is being considered, the determination will depend on how rigid the foot is when the health care provider tries to straighten it. If the foot is very flexible and easy to straighten or move in the other direction, no treatment may be needed. A pediatric orthopedic surgeon should be involved in treating more severe deformities. The child will be checked regularly.

Specific treatment for metatarsus adductus will be determined by your child’s doctor based on:

• Your child’s age, overall health, and medical history
• The extent of the condition
• Your child’s tolerance for specific medications, procedures, or therapies
• Expectations for the course of the condition
• Your opinion or preference

The goal of treatment is to straighten the position of the forefoot and heel. Treatment options vary for infants, and may include:

• Observation, for those with a supple, or flexible, forefoot
• Stretching or passive manipulation exercises. These are done if the foot can be easily moved into a normal position. The family will be taught how to do these exercises at home.
• Your child may need to wear a splint or special shoes, called reverse-last shoes, for most of the day. These shoes hold the foot in the correct position.
• Casts. Rarely, your child will need to have a cast on the foot and leg. Casts work best if they are put on before your child is 8 months old. The casts will probably be changed every 1 to 2 weeks.
• Surgery. Surgery is rarely needed. Most of the time, your provider will delay surgery until your child is between 4 and 6 years old.

Studies have shown that metatarsus adductus may resolve spontaneously (without treatment) in the majority of affected children.

Your child’s doctor may instruct you on how to perform passive manipulation exercises on your child’s feet during diaper changes. A change in sleeping positions may also be recommended. Suggestions may include side-lying positioning.

In rare instances, the foot does not respond to the stretching program, long leg casts may be applied. Casts are used to help stretch the soft tissues of the forefoot. The plaster casts are changed every 1 to 2 weeks by your child’s pediatric orthopaedist.

If the foot responds to casting, straight cast shoes may be prescribed to help hold the forefoot in place. Straight last shoes are made without a curve in the bottom of the shoe.

For those infants with very rigid or severe metatarsus adductus, surgery may be required to release the forefoot joints. Following surgery, casts are applied to hold the forefoot in place as it heals.

Metatarsus adductus long-term outlook

Metatarsus adductus is a common problem in babies with more than 90% resolving on their own. When needed treatment will depend on the degree of flexibility in the affected foot.

In-toeing does not interfere with the child becoming an athlete later in life. In fact, many sprinters and athletes have in-toeing.