Purpose. To establish the early outcome, satisfaction and complications of sinus tarsi implants in the management of symptomatic flexible flatfeet for a paediatric population. Methods and results. We included all patients aged 18 years or less who were treated for flexible flatfeet with a sinus tarsi implant between January 2010 and June 2012. We excluded patients who had a history of clubfeet or tarsal coalition. 34 patients had 59 implants. The mean age at surgery was 13.7 yrs (9–17 yrs), with mean follow-up of 22 months (range 10–35). Mean AOFAS improved from 65.7 to 87.9 (p<0.001), with an improvement in AOFAS pain scores (p=0.0001). Radiographic correction occurred in all feet, with average improvement of the anteroposterior talar-second metatarsal angle of 16 degrees, and the lateral talar-first metatarsal angle of 9 degrees. Implant placement satisfaction rate was 86%, with 81% claiming that they would have the procedure again. Complications included peroneal spasm (8%), extrusion (7%), revision (5%), and removal (5%). Peroneal spasm was recalcitrant in 3 of the 5 cases, and those with spasm had a higher average forefoot abduction measurement (35 degrees) than the remaining treated cases (25 degrees). Conclusion. In paediatric patients with flexible flatfeet, utilisation of the sinus tarsi implant has good short-term outcome, with our failure and revision rates comparable to other published studies in the adult population. We introduce the concept of isolated subtalar hyperlaxity which appeared to be a distinct etiological factor. A learning curve in assessing implant size was noted. Overcorrection and implant migration were the indications for revision surgery. Severe forefoot abduction appears to have a poorer outcome, and may be associated with peroneal spasm. Level of evidence: IV

Aim. Historically, surgeons have focused on isolated simple coalition resection in symptomatic tarsal coalition with concomitant rigid flat foot. However, recent evidence suggests that coalitions with severe preoperative planovalgus malposition treated with resection alone are associated with continued disability and deformity. We believe that concomitant severe flatfoot should be considered as much as a pathological component and pain generator as the coalition itself. Our primary hypothesis is that simple resection of middle facet tarsal coalitions and simultaneous flat foot reconstruction can improve clinical outcomes. Method. We identified eleven children (13 feet) who had resections of middle facet tarsal coalitions with or without complex foot reconstruction (calcaneal lengthening, medial cuneiform osteotomy) for concurrent severe planovalgus between 2003 and 2011. Clinical examination, American Orthopaedic Foot and Ankle Society (AOFAS) hind-foot scores, and radiographic assessments were evaluated after resection of middle facet tarsal coalitions with simultaneous flat foot reconstruction. Results. Isolated coalition resection provided short to intermediate term pain relief for three children that had this as a solitary procedure. Calcaneal lengthening osteotomy performed as an additional procedure in patients with very severe and stiff planovalgus provided excellent correction and symptomatic pain relief in all six patients (Mean AOFAS: 91). Two patients had insertion of sinus tarsi implants in addition to resection also had satisfactory hind foot function (Mean AOFAS: 87.3) post operatively. Conclusion. This study shows that calcaneal lengthening osteotomy in addition to coalition resection in patients with severe rigid flat feet provides excellent pain relief and function. Rigid flat feet should be considered as a significant contributor to the pain complex in this cohort of patients