Metatarsus adductus (MTA) or varus is a condition that is commonly seen in newborns and young infants, where the forefoot is twisted inwards relative to the hindfoot (or heel). Metatarsus adductus and Metatarsus varus are terms used interchangeably, and some doctors call the condition Metatarsus adductovarus. Some purists argue that there are subtle differences, but most doctors from a practical standpoint cannot and do not find a need to distinguish between them clinically. In MTA, the forefoot is turned inwards, while the hindfoot (or heel) is normal. If the hindfoot is involved, it becomes a more serious problem. If the forefoot adductus or varus is associated with hindfoot valgus, it is called a skewfoot. If the forefoot adductus is associated with hindfoot varus and ankle equinus where the foot points downwards, the problem is a clubfoot.
MTA is very common in the newborn, and is usually due to the feet being "packed" in the womb in that position. The forefoot adduction at this stage is very flexible, and with freedom of movement, this postural condition of MTA often improves over the next 6 to 12 weeks.
In about 15% of cases, the adducted position of the forefoot does not improve. In fact, the deformity becomes less flexible. A crease starts to appear on the medial border of the foot and a bony "bump" on the lateral border of the foot, right at the junction of the forefoot and hindfoot. This is the classic MTA that may require treatment.
The picture above shows slight adductus at birth which usually corrects spontaneously after 2 to 3 months (indicated by horizontal arrow). In some cases, instead of correcting, it persists or gets worse, forming the typical deformity of metatarsus adductus (indicated by downward arrow).
Diagnosis and Treatment
MTA that is diagnosed at birth does not require treatment. It is usually postural, and with growth, the MTA resolves spontaneously over a period of 6 to 12 weeks. If the forefoot adductus is severe, your doctor may prescribe stretching exercises which he will teach you to perform at home on the baby. X-rays are usually not necessary, unless the doctor suspects something else.
After about 3 to 4 months of observation and stretching exercises, if the forefoot adductus does not improve, treatment may be necessary. The treatment options are as follows:
As stated above, without treatment, 85% of MTA’s resolve spontaneously. There remains 15% that requires treatment. Your doctor will decide with you in terms of the timing and mode of correction, whether by corrective casting or bracing. Once correction has been obtained, recurrence is unlikely.