Subtalar extra-articular screw arthroereisis (SESA) for the treatment of flexible flatfoot in children

Purpose The aim of this study was to describe a subtalar extra-articular screw arthroereisis (SESA) technique for the correction of flexible flatfoot (FFF) in children and report the outcome. Methods From 1990 to 2012, data were collected on 485 patients who underwent SESA at the San Raffaele Hospital. The average age of the patient cohort was 11.5 +/- 1.81 years (range 5.0-17.9 years; median 11.5 years). Inclusion criteria were FFF and marked flexible hindfoot valgus, and the exclusion criterion was rigid flatfoot. SESA was performed in 732 cases of FFF-bilaterally in 247 patients and monolaterally in 238 patients. Results The values of the pre-and post-SESA weightbearing X-ray angles were 146 degrees +/- 7 degrees and 129 degrees +/- 5 degrees, respectively, for the Costa-Bartani angle, 43 degrees +/- 8 degrees and 25 degrees +/- 6 degrees, respectively, for the talar inclination angle and 11 degrees +/- 6 degrees and 14 degrees +/- 5 degrees, respectively, for calcaneal pitch (p < 0.001). All data were analysed statistically with Student's t test. Data on 398 patients were ultimately available for analysis. In 93.7 % of cases the results were good in terms of improved clinical aspects and X-ray measurement, absence of complications, normal foot function 3 months post-SESA and no requirement for further surgery. The complication rate was 6.3 % and included ankle joint effusion, painful contracture of peroneal muscles and fourth metatarsal bone stress fractures. A sample of 76 patients (121 feet) were evaluated after screw removal, which occurred on average 2.9 years after SESA. The angle measurements of this sample showed no statistically significant modification. Conclusion Based on our <20 years of experience, we believe that SESA is an optimal technique for the correction of FFF as it is simple and can be performed rapidly, and the corrective effect results from the screw's mechanical and proprioceptive effect. The indication for surgery must be accurate. We suggest that the patient be at least 10 years of age in order that all of the foot's growth potential can be utilized and to allow for spontaneous resolution and thereby avoid the possibility of over-treatment.