Sometimes, a patient can present with a “sudden flatfoot”. They relate functioning normally, then suddenly, typically after a trauma (large or small), their foot flattens and heel rolls with associated pain in the rear-foot and ankle. This rarer type of flatfoot is typically caused by a spasm of the peroneal tendons on the outside of the ankle/rear-foot, and is referred to as peroneal spastic flatfoot. Many times, this condition is a symptom of something called a tarsal coalition. A tarsal coalition is an irregular union of two bones of the rear-foot which should not be present. The coalition could be made of fibrous tissue, cartilage or bone. Many people who have tarsal coalitions don’t know about it until they somehow injure the coalition. This typically occurred in teenage years, as patients become more active in athletic activity. However, it can also present earlier or in adulthood. As the coalition is damaged, the peroneal tendons go into spasm as a splinting mechanism. Essentially, as the tendons pull tighter, they restrict the range of motion of the painful joint. This pulling motion causes the foot to flatten as it pulls the heel outward and the arch downward. Sometimes the foot goes through period of spasm and relaxation, while other times the foot stays in a flattened position.
Conservative measures aim to reduce pain and attempt to release the spasm. These measures usually include rest, ice, anti-inflammatories, a period of casting, and injection of nerves to help release the spasm. However, once symptoms start, many patients end up requiring surgical intervention. Depending on the severity of the coalition and the joints involved, some patients will have the coalition removed (many times placing a spacer between the joints). Other times, after resecting the coalition, the joints involved may need to be fused together to diminish pain and prevent re-occurrence. If you develop he sudden flatfoot, seek medical attention ASAP.