Metatarsus adductus, also known as metatarsus varus, is a common foot deformity noted at birth that causes the front half of the foot, or forefoot, to turn inward. 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).
What causes metatarsus adductus?
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.
Babies born with metatarsus adductus rarely need treatment as they grow. They may, however, be at increased risk for developmental dysplasia of the hip, 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.
How is metatarsus adductus diagnosed?
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.
Treatment for metatarsus adductus
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
Studies have shown that metatarsus adductus may resolve spontaneously (without treatment) in the majority of affected children.
Your child's doctor or nurse 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.
Long-term outlook for a child with metatarsus adductus
Metatarsus adductus is a common problem with more than 90% resolving on their own. When needed treatment will depend on the degree of flexibility in the affected foot.