Clinical and Radiological Outcomes of Subtalar Kalix II Arthroereisis for a Symptomatic Pediatric Flexible Flatfoot

Background. The purpose of this study is to evaluate functional and radiological outcomes of subtalar arthroereisis in the treatment of symptomatic pediatric flexible flatfeet. Methods. A total of 16 patients (26 feet) were treated with a Kalix II as subtalar motion blocker between 2009 and 2014. Calcaneal pitch (CP) and Meary’s angle (MA) were measured on radiographs preoperatively, directly postoperatively, and at follow-up 47 ± 17 (range 19-79) months. Patient satisfaction surveys were used to assess functional outcome and patient satisfaction. Results. Surgery was performed mostly for pain, walking problems, or a combination of both at a mean age of 12.5 ± 1.5 (range 10-15) years. Symptoms were relieved in 62.5% of patients in the postoperative phase and increased to 68.75% at follow-up. A statistically significant increase in CP of 2.8° and decrease in MA of 14.0° was observed directly postoperatively, which persisted during the follow-up period irrespective of Kalix removal. Revision surgery was necessary in 6 cases (23%) because of arthroereisis migration. Conclusion. Subtalar Kalix II arthroereisis significantly reduced clinical symptoms and improved the CP and MA directly postoperatively, which persisted during follow-up, irrespective of Kalix removal. Therefore, subtalar arthroereisis is a considerable intervention to reduce symptoms in children with symptomatic flexible flatfeet. Levels of Evidence: Level IV: Case series