Midterm assessment of subtalar arthroereisis for correction of flexible flatfeet in children

The role of subtalar arthroereisis (STA) for treating flexible flatfoot (FFF) in children is controversial. We hypothesized that (1) STA provided significant radiographic correction of low longitudinal arch and forefoot abduction in paediatric FFF and that (2) mid-term clinical outcomes were satisfactory and comparable to a normal population.

A retrospective comparative study was performed of paediatric patients with symptomatic FFF who underwent STA between 2012 and 2015. Multiple measurements on preoperative and latest follow-up radiographs were recorded by two observers and compared to assess for correction of the FFF. Intra- and inter-observer reliability was also assessed. Ankle and hindfoot range of motion (ROM), AOFAS hindfoot score and VAS-FA score were compared with controls without foot symptoms or deformity. From 70 consecutive feet, 62 (31 patients) treated at 10.5 years of age were identified and compared to 48 controls (24 patients). Mean follow-up was 62 months.

Intra- and inter-observer reliability was excellent for all angles (range, 0.81-0.97). Radiographic measurements demonstrated significant improvement after surgery (p<0.001) but significance was not reached in talonavicular coverage angle (p=0.49) and calcaneo-fifth metatarsal angle (p=0.53) on dorsoplantar view. At latest follow-up, patients had less hindfoot inversion than controls (15.1̊ vs. 19.3̊, p=0.03), lower AOFAS scores (94.1 vs. 99.6 points, p=0.01), due to pain (p=0.01) and alignment (p=0.006) subscores. Using the VAS-FA score, patients were found to demonstrate higher pain at rest (prange, 0.02-0.03) and during activity (p=0.009), and felt limited when standing on one leg (p range, 0.01-0.03) and running (p=0.04). No loss of correction was found after removal of the implant.

This study showed that STA corrected the low longitudinal arch in symptomatic paediatric FFF, but did not correct forefoot abduction in relation to the hindfoot. Mid-term assessment revealed STA provided satisfactory ankle and hindfoot ROM, pain and function levels, but limitations are witnessed compared to unaffected individuals. This aspect should be considered when counselling patients and their parents or caregivers to allow for realistic expectations.

III, retrospective comparative study.