Q: What is a tarsal coalition? I know it's in the foot but I don't know what it is exactly.
A: Tarsal coalition is the failure of the developing bones in the foot to properly form all the distinct, individual bones in the midfoot (between the ankles and toes). Instead, two or more bones can form a bridge of bone between them or fuse together. Males are affected more often than females though the reason for this remains unknown.
This condition is usually congenital (present at birth) and there are inherited factors involved. Tarsal coalition can also develop after birth as a result of trauma, infection, or inflammation (e.g., arthritis). In some cases, tarsal coalition is part of a larger problem with other bony malformations.
The most obvious symptom of tarsal coalition is a rigid flatfoot. An X-ray or other imaging study provides a look inside the foot to confirm the diagnosis. CT scans are especially helpful to see exactly what's going on. This information helps the surgeon know how to best treat the problem.
The condition can be asymptomatic (no symptoms present). Symptoms such as pain and stiffness don't develop in children until the connecting tissue between the bones hardens or ossifies forming a bony bridge. Increased activity (e.g., sports or dance) involving the feet may aggravate the child, teen, or young adult. Sometimes it's weight gain or repeated ankle sprains that bring on symptoms of pain, foot fatigue, or limping. Muscles in the foot may spasm in an effort to protect the foot adding to the discomfort.
Treatment is usually conservative (nonoperative) but surgery may be needed in some cases. Treatment and results depend on the severity of the condition, any complications that may develop, and activity level of the affected individual.
Reference: Katharine Thomason, and Michael M. Stephens, MSc, FRCSI. Tarsal Coalition. In Current Orthopaedic Practice. May/June 2012. Vol. 23. No. 3. Pp. 229-234.