Researchers have made attempts using preoperative CT scans to determine whether the size of a talocalcaneal coalition affects the result obtained with resection. Wilde and colleagues examined 20 feet in 17 patients, all less than 16 years of age and each undergoing resection of a talocalcaneal coalition.10 These investigators reported excellent or good results in 10 (50 percent) feet in patients in whom the preoperative coronal views on the CT scan showed less than 50 percent involvement of the posterior facet of the subtalar joint. These patients also had less than 16 degrees of heel valgus and no radiographic signs of arthritis of the posterior facet of the talocalcaneal joint.
In the 10 feet with fair or poor results, coronal CT sections showed greater than 50 percent involvement of the posterior facet.10 The patients also had greater than 16 degrees of heel valgus and radiographic changes of the posterior facet consistent with arthritis. These investigators concluded that one could obtain excellent or good results if the coalition involved less than 50 percent of the joint, but fair or poor results occurred with attempts at resection of larger coalitions.
Similarly, Comfort and Johnson found that the clinical results obtained with resection correlated well with the size of the coalition.11 These authors reviewed a series of 20 feet undergoing resection of talocalcaneal coalitions (16 patients). There were preoperative CT scans for 17 feet. The average patient age was 14.2 years and the mean follow-up was 2.4 years postoperatively. Unlike Wilde and associates, these authors evaluated all three facets of the subtalar joint and not just the posterior facet. They found 77 percent excellent or good results when the coalition involved less than one third of the entire subtalar joint as measured on a coronal CT view.
Therefore, the size of the tarsal coalition seems to have relevance in the choice of a surgical plan for patients with intra-articular tarsal coalitions. However, researchers have not determined a threshold size that precludes resection.
Other Pertinent Surgical Insights
The patient and/or parents of the patient should be involved in the selection of an appropriate surgical treatment plan. If the surgical plan one chooses is a resection procedure, review the potential need for future arthrodesis with the patient and/or parents prior to surgery. In the best of circumstances, a percentage of patients undergoing a resection procedure will fail to improve and will require an arthrodesis approach.
Typically, the arthrodesis approaches include a single arthrodesis procedure, such as a subtalar joint arthrodesis for a middle facet talocalcaneal coalition, or a triple arthrodesis for more advanced deformities, such as a calcaneonavicular coalition or talocalcaneal coalition in a patient with severe secondary arthritic changes. When performing an arthrodesis approach, the position of the arthrodesis is critical to the success of the procedure. Severe heel valgus is often associated with a tarsal coalition. One must address and correct this during the fusion procedure.
When the surgeon performs resection of a tarsal coalition, following several principles will maximize success. First, approach the coalition as directly as possible. Second, perform a generous resection of the tarsal coalition. Third, if one inserts interpositional materials into the defect, they should be as inert as possible and minimize scar tissue formation. Fourth, perform early mobilization of the resected area postoperatively. Finally, one will need to address any associated pes planovalgus deformity either simultaneously or postoperatively with conservative measures or at a second surgical sitting.