How To Detect And Treat Tarsal Coalitions

Author(s): 
By Justin Franson, DPM, and Babak Baravarian, DPM

   A 20-year-old male presents to your office with a painful sinus tarsi, medial arch and a history of recurrent ankle sprains over the last few years. The pain seems to limit his activities more and more, and he is frustrated with his lack of improvement. He has seen a few doctors for this problem, and has been treated with orthotics, ankle braces, physical therapy and NSAIDs. He wants to know why he is not getting better and what you can do to get him back to playing tennis.

   The majority of patients who walk (or limp) into our offices have conditions that are relatively common and they subsequently undergo a sometimes routine treatment protocol. However, tarsal coalition is a pathology that occurs less frequently and the treatment options can be challenging and sometimes less predictable. Having a thorough understanding of this condition can help facilitate improved patient outcomes.

A Guide To The Different Types Of Tarsal Coalitions

   Tarsal coalition is a bridging between two bones that limits or eliminates the normal motion between them. It is largely attributed to a congenital etiology, a genetic mutation that leads to an embryologic failure of differentiation and segmentation of primitive mesenchymal cells. One may see this in acquired conditions but this is less common. Clinicians may encounter osseous (synostosis), fibrous (syndesmosis) or cartilaginous (synchondrosis) coalitions.

   Approximately 90 percent of tarsal coalitions are talocalcaneal (intraarticular) or calcaneonavicular (extraarticular), according to the literature. Less common coalitions include talonavicular, calcaneocuboid, cubonavicular, naviculocuneiform or some combination of these. Middle facet coalitions are the most common coalition of the subtalar joint. Keep in mind that coalitions are often bilateral. One may see this in nearly half of patients presenting with a coalition.

   Tarsal coalition in the congenital form often remains asymptomatic until the patient is in late childhood or adolescence, and sometimes into early adulthood. The reason for this quiescent period, void of dysfunction or symptoms, is most likely due to the cartilaginous nature of the coalition, which allows some motion. As the coalition begins to ossify and further restrict motion, the condition becomes painful.

   Another reason for the delay in symptoms can be due to arthritic changes that develop over time. If this were the case, then resection would likely be less successful.

   As for the timing of coalition ossification, talocalcaneal coalitions commonly occur between the ages of 12 to 15 whereas calcaneonavicular coalitions commonly occur between the ages of 8 to 12.

Essential Diagnostic Insights

   During the examination, it is clear the 20-year-old patient has a decreased medial arch height on the affected side when he is bearing weight. The calcaneus is in a valgus position to the leg and there is limited subtalar joint motion. He has tenderness near the sustentaculum tali and the sinus tarsi, and his lateral ankle ligaments are tender to palpation. He also has mild edema laterally.

   To compensate for the limitation of normal subtalar joint motion during the stance phase of gait, the surrounding tarsal joints exhibit flattening of the foot with a decrease in the longitudinal medial arch. The calcaneus assumes a valgus position to vertical. Over time, the peroneal tendons will assume an adapted shortened position and undergo spasm if one attempts to protect and splint the pathology. Over time, peroneal spastic flatfoot can develop. The lack of internal rotation in the subtalar joint leaves the lateral ankle prone to instability.

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