Painful ankles, unusual stiff walking, inability to stand on outside borders of the feet? These can all be possible signs of a tarsal coalition. Tarsal coalitions are an infrequent but often mis-diagnosed cause of foot pain.
What are Tarsal Coalitions?
Coalitions are connections between the tarsal (rearfoot) bones that are not seen in the majority of the population. These connections (coalitions) can be made of bone (osseous) or soft tissue (synchondrotic or syndesmotic) and alter the flexibility and function of the rearfoot joints.
The incidence of tarsal coalitions is approximately 1-2% of the population with a greater rate in males than females. They can become painful around the late primary school years as the foot starts to develop more solid bone at this stage. In some cases they can be pain free through to adulthood and become apparent after an ankle sprain or similar soft tissue injury.
Signs and symptoms
Symptoms associated with coalitions (pairs of duckfeet) can be deep ankle or rearfoot pain during and after exercise, reduced range of motion and the inability to put the foot into some positions. Patients with coalitions will often have stiff and flat feet and when challenged to walk on the outside border of their feet be unable to do so.
When there is a high degree of clinical suspicion your podiatrist may refer you for imaging to investigate the shape of the tarsal bones. After confirmation of the presence of a coalition, in shoe padding or strapping can be trialled to reduce stress over this irritated structure. As the shape of the foot can be a little different from the norm the required padding is often very specific to the foot and off-the-shelf options may not be helpful (and can sometimes make it worse). However with the correct offloading we can expect good improvement in symptoms and a good return to activity. Surgery is infrequently used as a treatment and reserved for cases responding poorly to conservative care.