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.    Routine radiographs often will provide only subtle findings that indicate a tarsal coalition. While the “anteater” sign associated with the calcaneonavicular bar is often readily apparent on routine radiographs, talocalcaneal coalitions are less obvious on the standard three views we commonly order. The “C” sign, formed by a line tracing the dome of the talus and the inferior border of the sustentaculum tali, is suggestive of a middle facet coalition that one would see on the lateral view.    When suspicious of subtalar coalition, obtaining the Harris Beath axial calcaneal “ski jump” views should allow one to see middle facet coalitions with this approach.    If there is an osseous coalition, there will be no joint space at all. If there is a fibrous or cartilaginous coalition, it will appear as an irregular or a joint line angled inferior and medial. Broden’s views are less commonly needed in this clinical scenario.    Coronal CT scans have become the gold standard for coalition imaging. Obtaining an MRI is also useful, especially in cases of fibrous or cartilaginous coalitions.

What You Should Know About Conservative Treatment

   The conservative treatment of tarsal coalition is designed to support and limit the pronatory forces through the subtalar and midtarsal joints, and reduce strain on the coalition. An initial period of immobilization is helpful to address the acutely painful, inflamed and peroneal spastic condition. One could consider antiinflammatory medication, including NSAIDs or steroid injections, in the acute case.    Following this initial period of immobilization, one should pursue aggressive orthotic control. Employing a UCBL device can support the medial foot and limit the pronatory forces. Given the high incidence of lateral ankle instability and ligamentous laxity that clinicians often see in these patients, one may want to consider some ankle bracing techniques, including the various ankle foot orthoses that are available.    Some sources state that talocalcaneal coalitions respond only about one-third of the time to conservative treatment, indicating a high incidence of failure with conservative methods. Other sources report better conservative treatment response with talocalcaneal coalitions than with calcaneonavicular coalitions.

When Is Resection Or Arthrodesis Appropriate?

   When surgical treatment is indicated, do you fuse or not fuse? In younger patients, resection is often indicated in the absence of compounding pathology. As the patient gets older, the options become more limited. While extraarticular tarsal coalitions such as the calcaneonavicular bar may respond well with surgical resection in the young adult, arthrodesis is the traditional and preferred approach to the intraarticular talocalcaneal coalition in the adult.    Arthrodesis may be hard for some younger patients to accept. In the case of the 20-year-old male with a middle facet coalition that appears to be partially a fibrous coalition, one may consider resection. However, when the patient has an associated flatfoot deformity, the surgical results tend to be less predictable and adjunctive procedures may be indicated. Arthrodesis would likely provide a satisfactory and more predictable result.    There are certain factors that can be of predictive value in these cases of tarsal coalition in the young adult. These include patient age, the presence of compounding deformities and surrounding arthritic changes.    Paying close attention to standard radiographs is important in order to detect arthritic changes in the surrounding joints. This does have predictive value as arthritic changes typically indicate that resection will be less successful. If the patient is a young adult with no surrounding arthritic changes and the position of the hindfoot is rectus, one can consider resecting the intraarticular coalition. The patient should understand and consent to the potential need for arthrodesis should this procedure fail.    Global degeneration surrounding coalitions are an indication for arthrodesis. One can often consider a triple arthrodesis in cases of extra- or intraarticular coalitions.

When Adjunctive Procedures Come Into Play

   One should be aggressive with coalition resection, especially in the case of a calcaneonavicular bar. When performing a block resection of the coalition, surgeons should avoid the talonavicular joint and consider implanting the extensor digitorum brevis muscle belly in the resection void. Alternatives to this include using bone wax or performing electrocautery of the resected ends.    If associated deformities are present, it is important to address these surgically when appropriate. Resecting a coalition will provide additional motion, which could accelerate or uncover other deformities. Evaluate the calcaneal inclination angle and the position of the heel while the patient is weightbearing.    Obtain axial calcaneal views to determine if there is valgus positioning of the calcaneus. If there is a pes planus with associated hindfoot valgus deformity, one may consider subtalar arthroeresis after resecting a subtalar coalition.    Consider calcaneal osteotomies to realign the hindfoot when appropriate. Always evaluate for equinus and consider a gastrocnemius recession or tendo-Achilles lengthening as needed.

What The Postoperative Course Should Entail

   Postoperative management of the coalition resection should include aggressive physical therapy. This will help prevent arthrosis of the resected margins. Avoid an extended period of nonweightbearing unless associated realignment osteotomies of the rearfoot were necessary.    In cases of arthrodesis, non-weightbearing and cast immobilization are obviously indicated until one sees clinical and radiographic healing.    Patient education is very important in achieving the successful outcome in tarsal coalition cases. It is a severe condition that may require arthrodesis of the largest joint in the foot at an early age. Dr. Franson is an Associate of the Foot and Ankle Institute of Santa Monica. He is an Attending Podiatrist at the West Los Angeles Veterans Affairs Healthcare Center and the Olive View/UCLA Medical Center. Dr. Baravarian (shown here) is Co-Director of the Foot and Ankle Institute of Santa Monica. He is an Associate Professor at UCLA Medical Center and is Chief of Podiatric Surgery at Santa Monica/UCLA Medical Center. Dr. Baravarian may be reached via e-mail at: bbaravarian@mednet.ucla.edu.

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