Outcome after subtalar screw arthroereisis in children with flexible flatfoot depends on time of treatment: Midterm results of 95 cases.

ABSTRACT

OBJECTIVES: The subtalar screw arthroereisis (SSA) is a treatment option for painful pediatric flexible flatfeet (PFF). Hence, the optimal time point for a SSA is discussed controversially. Therefore the present study evaluates the influence of the patient's age at surgery on the radiological outcome to provide further evidence in this matter. METHODS: From 08/2007 to 12/2015 50 patients with 95 PFF were included. Inclusion criteria were 1) Patients with PFF under or equal 15 years of age, 2) treatment with SSA and 3) presence of pre-op, post-op and follow up (FU) routine biplane radiographs. A subdivision was made into group A 5-8 years, group B 9-12 years and group C 13-15 years. The radiographs were analyzed for 1) calcaneal-pitch (CP), 2) lateral talocalcaneal angle (lat. TCA), 3) a.p. talocalcaneal angle (a.p. TCA, kite angle) and 4) navicular-cuboidal-index (NCI) and meary angle. RESULTS: Our study showed the best deformity correction when surgery was conducted between 9 and 12 years of age (group B), with significant improvement in all measured parameters without secondary deterioration during FU. In group A, the SSA show inferior results with poorer long-term success with only an improvement in the a.p. TCA. Group C showed mixed results. While CP and NCI improved, the lat. TCA deteriorated in FU. In conclusion, the ideal age for surgical intervention by SSA is between 9 and 12 years. Surgery before the age of 8 years did not show long-term success and delayed treatment at the age of 13-15 was only partially successful with deterioration during FU period. LEVEL OF EVIDENCE IV.