The Predictability of Clinical Findings and Radiographs for Detecting Tarsal Coalition.

Introduction: Tarsal coalition is a disorder of the foot characterized by the abnormal union between 2 or more of the tarsal bones. A minority of patients will develop pain and limited motion when reaching adolescence, for whom surgical resection of the coalition may be necessary. The diagnostic value of clinical and radiologic signs remains unclear. The aim of this study is to assess the predictive value of clinical symptoms and plain x-rays to diagnose tarsal coalition in symptomatic patients.

Methods: We performed a retrospective chart review of patients with clinical suspicion of tarsal coalition between January 2011 and November 2019. Patient demographic data; clinical data on pain, limited motion, peroneal spasm, recurrent, or previous trauma; and radiologic data on the presence and type of coalition were collected. Multivariable general estimating equations analysis was used to assess associations between demographic and clinical characteristics and the likelihood of a positive coalition diagnosis.

Results: The study cohort was 336 patients (672 feet) with a mean age of 13 years and a 1:1 sex distribution. Thirt-eight percent of feet were diagnosed with a coalition of which 53% were talocalcaneal and 41% were calcaneonavicular. Coalitions were significantly more common in younger patients, males (OR 1.66, P=0.04), patients with lower BMI (OR 0.96, P=0.045), and patients who presented with painful feet (OR 1.59, P=0.04) or feet with limited motion (OR 7.49, P<0.001). Diagnostic utility of plain x-ray compared with CT diagnosis yielded a sensitivity of 76% and a specificity of 94%, with higher sensitivity (90%) in calcaneonavicular coalitions than in talocalcaneal (66%).

Discussion: Our study shows that limited subtalar movement, male sex, and low BMI have a high predictive value for tarsal coalition in symptomatic patients. Classic clinical findings that were not predictive of coalition in our cohort of symptomatic patients included peroneal spasm, recurrent ankle sprains, and recent trauma. Plain x-rays offer a reliable alternative to CT for diagnosis, especially for calcaneonavicular coalitions.

Level of evidence: Level III-retrospective comparative study.