Offering insights from the literature as well as clinical experience, this author discusses conservative modalities, reviews important considerations for choosing an optimal surgical procedure and shares pearls on resection and arthrodesis options.
A tarsal coalition exists when an abnormal union causes restricted motion or absence of motion between two or more tarsal bones. Tarsal coalitions often produce a dramatic symptom complex, which one may ultimately identify as rigid peroneal spastic flatfoot.
Three clinical findings in the midfoot and/or rearfoot — pain, limitation of motion and muscle spasm — should make the clinician suspect a tarsal coalition. Additionally, prolonged pain after a simple ankle sprain or injury in an adolescent or young adult as well as a lack of response to treatment should make one suspicious for a tarsal coalition.
One ultimately diagnoses a tarsal coalition through a combination of the characteristic symptom complex, clinical acumen and radiographs. Physicians may also consult advanced imaging studies such as computed tomography (CT) scans, magnetic resonance imaging (MRI) or both.
After one establishes the diagnosis, the treatment can focus on reducing symptomatology and restoring as much function as feasible. It is rare for the treatment of a tarsal coalition to fully restore normal foot function. Therefore, an improvement in the patient’s quality of life is the primary goal of any treatment plan.1
A Closer Look At Effective Conservative Treatments
A tarsal coalition may be asymptomatic and an incidental finding on routine radiographs or an advanced diagnostic imaging study. In a study of 23 patients with tarsal coalition, Jack found that five patients (22 percent) had no symptoms.2 If an asymptomatic tarsal coalition is present, no treatment is mandated. However, one should counsel the patient regarding the finding and the potential need for treatment should the coalition result in future symptomatology.
When a tarsal coalition becomes symptomatic, it does not necessarily remain symptomatic. For a symptomatic coalition, one should generally initiate conservative treatment directed toward restriction of subtalar and midtarsal joint motion. This results in a reduction of pain and muscle spasm. One may combine this approach with anti-inflammatory medication and physical therapy as needed.
Shoe modifications, padding, orthotic devices or casting may adequately limit subtalar and midtarsal joint motion. Shoe modifications may include a Thomas heel, a medial heel wedge or a longer medial heel counter. Padding in the shoe may include a heel wedge or a medial longitudinal support.
One should specifically construct orthoses to limit subtalar joint motion. A neutral position device with a long rearfoot post or an orthotic device posted in valgus may prove to be beneficial. University of California Biomechanics Lab (UCBL)-type orthoses with high medial and lateral flanges may also be helpful. If these fail or if the patient has significant symptoms, consider a soft cast, strapping, cast boot or a below knee walking cast.3 If desired, one may apply these devices after a local corticosteroid injection to the area of the coalition.
Apply the below knee cast or cast boot with the ankle and subtalar joints in their neutral positions and keep this intact for three to six weeks. In more severe cases or if initial immobilization fails, one may attempt to apply a non–weightbearing cast. If this approach is going to be effective in this situation, more than one trial of immobilization may be necessary to attempt to render the patient free of symptoms.4,5