Subtalar Arthroereisis for Correction of Flexible Flatfoot in Children: A Retrospective Comparative 5- Year Follow-Up Study

Abstract

Category: Hindfoot Introduction/Purpose: Subtalar arthroereisis for the treatment of flexible flatfoot in children is controversial. Self-locking implants are utilised worldwide aiming to limit subtalar joint movement and foot pronation. Recently two reviews have focused on the lack of comparative studies in literature and the poor-quality evidence available regarding these devices. In this study, performed on children diagnosed with flexible flatfoot and treated with subtalar arthroereisis, the two aims were: 1) to compare pre and postoperative radiographic measurements in order to assess the efficacy of arthroereisis in the correction of flatfoot; 2) to compare clinical outcomes between patients operated and normal controls at mid-term follow-up. Our hypothesis was that subtalar arthroereisis achieves flatfoot correction and that at the longest follow-up patients operated do not differ from normal controls. Methods: This is a single-centre single-surgeon retrospective comparative study, ethics committee approved. Fortysix feet from 24 continuous patients (5 females; 22 left and 24 right) treated at mean age of 11 years (range 8 to 15) with subtalar arthroereisis for flexible flatfoot were reviewed at a follow up of 51 months (range, 25 to 73) and compared with 23 feet from 13 controls (ratio 2:1, matched by age and body mass index). Radiographically, the following measurements were recorded and compared on pre and postoperative films: talonavicular coverage angle and talocalcaneal divergence angle on dorsoplantar view; Dijan-Annonier angle, Méary line, calcaneal pitch and talocalcaneal divergence angle on lateral views. Clinically, a goniometric assessment of ankle and hindfoot range of motion, AOFAS score and VAS-FA score were utilised in patients operated and normal controls (mean values ± standard deviation). Paired 2-tailed Student t tests were used to assess differences. Results: All radiographic measurements demonstrated improvement after surgery (p .001), except for the talonavicular coverage angle (p .812). At longest follow-up, patients and controls had 35.8° ± 3.8 vs 44.1° ± 2.8 of plantarflexion (p .092), 13° ± 1.7 vs 14.5° ± 2 of dorsiflexion (p .312), 16.5° ± 2 vs 18.7° ± 1.6 of inversion (p .124) and 10.6° ± 1.6 vs 11.8° ± 1.3 of eversion (p .073). AOFAS values were similar at 94.7 points ± 3.9 (patients) and 99.3 points ± 1.3 (controls) (p .083). All the items from VAS-FA showed no differences in two groups, except for frequency and intensity of pain during physical activity (p .053 and p .032, respectively) and ability to stand on leg for long time (p .004). Conclusion: Our study showed that subtalar arthroereisis significantly improves flexible flatfoot deformity, with a satisfactory correction of hindfoot alignment and longitudinal arch but no significant amelioration of the foot abduction. Although at 4 years of time patients do clinically well, they may still experience some limitations compared to normal individuals. It is therefore crucial to consider these anatomical and functional elements when counseling young patients and family about surgery, in order to address preoperatively and realistically their expectations.