A Clinically Relevant Classification System for Pediatric Talocalcaneal Coalition.

Introduction: Talocalcaneal coalition (TCC) is one of the most common tarsal coalitions in children. However, current classifications of TCC are limited and focus on histologic or morphologic features without clinical correlation or therapeutic guidance. Moreover, no classification system specifically designed for pediatric populations. We hypothesize that the novel classification system will be clinically relevant, reliable, and easy to use for pediatric TCC management.

Methods: A total of 43 patients (58 feet) with pediatric TCC confirmed by 3-dimensional CT scans were included in this study. All cases were classified according to the novel classification system: type I (middle facet TCC), type II (posterior facet TCC), and type III (extra-articular TCC). Three pediatric orthopaedic surgeons with varying levels of experience independently classified the 58 cases to assess interobserver agreement. For all patients, we documented the hindfoot alignment (valgus, varus, or neutral), presence of pain, peroneal muscle spasm, tarsal tunnel syndrome, treatment strategies, surgical duration, preoperative and postoperative AOFAS and VAS scores, and complications.

Results: A total of 22 type I, 9 type II, and 27 type III TCC cases were identified, with a mean age of 10.9 years. The new classification system demonstrated almost perfect interobserver agreement (kappa=0.90). Type I showed the highest valgus prevalence (59%, 13/22; P=0.004), type II predominant varus (67%, 6/9; P<0.001), and type III neutral alignment (52%, 14/27; P=0.515). Medial displacement calcaneal osteotomy was performed in 14% (3/21) of type I cases, and lateral displacement osteotomy in 42% (5/12) of type II and III cases. All types achieved significant AOFAS/VAS improvement. Type III TCC had the shortest operative time (52 min; P <0.001) and no complications.

Conclusion: We propose a novel classification system for pediatric TCC that is clinically relevant, reliable, and easy to use. Type I TCC is more often associated with hindfoot valgus, while type II TCC frequently presents with hindfoot varus. Types II and III TCC more commonly require lateral displacement calcaneal osteotomy for varus correction. Type III TCC showed the most favorable surgical outcomes, with the shortest operative times and lowest complication rates among all types.

Level of evidence: Level III-diagnostic study.