Bioabsorbable Calcaneo-Stop Implant for the Treatment of Flexible Flatfoot: A Retrospective Cohort Study at a Minimum Follow-Up of 4 Years

Abstract

Arthroereisis of the subtalar joint is a common surgical technique in Europe for the management of flexible flatfoot in the pediatric population. In most cases, it is performed using a calcaneo-stop metallic screw. Despite the good clinical results, screw removal is always advised after 2 to 3 years. The use of a bioabsorbable screw might overcome the need for a second operation to remove a nonabsorbable device. We report the results of a biodegradable calcaneo-stop screw at a minimum of 4 years of follow-up. Eighty-eight procedures were performed on 44 children. All patients were clinically and radiologically evaluated preoperatively and at a minimum 4-year follow-up period. Patient satisfaction and plantar collapse using Viladot's classification were recorded. Meary's talus-first metatarsal angle and talocalcaneal angle were measured on radiographs preoperatively and at the last follow-up visit. The presence of the device at the last follow-up examination was assessed by magnetic resonance imaging. The mean follow-up duration was 56 months. Of the 44 patients, 33 (75%) reported excellent clinical outcomes, 9 (20.5%) good outcomes, and 2 (4.5%) poor. Foot print improvement was registered for all patients. The mean Meary's talus-first metatarsal angle had improved from 160.6° ± 7.7° preoperatively to 170.6° ± 6.5° at the last follow-up visit (p < .001). The talocalcaneal angle had decreased from 39.9° ± 5.2° preoperatively to 29.4° ± 4° at the last follow-up examination (p < .001). At the 4-year follow-up point, the implant could be seen to have almost completely biodegraded on magnetic resonance imaging. Two screw breakages occurred. The bioabsorbable calcaneo-stop screw seems to be an effective solution for flexible flatfoot in pediatric patients. Also, owing to its biodegradable composition, the need of a second operation for implant removal will not always be necessary.

Keywords: arthroereisis; pediatric; pes valgus; subtalar joint.