Sinus tarsi syndrome in a patient with talipes equinovarus.
The literature reports that 70% of the cases of sinus tarsi syndrome are post-traumatic, following an inversion sprain, and that 30% result from inflammatory disorders, such as rheumatoid arthritis, ankylosing spondylitis, and gouty arthritis. However, in the case presented, talipes equinovarus deformity and sinus tarsi syndrome coexisted. One of the corrective goals in the management of the talipes equinovarus deformity is the realignment of the articulation between the medial plantarly deviated talar head and the anteromedial segment of the calcaneus. The calcaneus must be rotated from a plantarflexed position into a dorsiflexed position. The posterior tubercle will be moved down and in, with the anterior process moved up and out away from the talar head. By correcting the plantarflexed varus attitude of the calcaneus, it is put in a valgus position that often closes down the sinus tarsi upon weightbearing. This compression may result in pain over the lateral aspect of the midfoot with hindfoot instability, as seen in the case presented. As a result of the abnormal anatomical relationship of the talus and calcaneus, the patient developed severe pain in the sinus tarsi. Based on the medical history and present postoperative results, the authors find a long-term sequela of talipes equinovarus deformity to be sinus tarsi syndrome.