The purpose of this study was to evaluate the clinical, functional and radiological outcome of lateral calcaneal lengthening osteotomy and medial soft tissue plication for correction of symptomatic flatfoot deformity in children. A prospective multicenter study on 22 feet of 20 patients who underwent lateral calcaneal lengthening for symptomatic flatfoot in children by Mosca technique in the period between December 2017 and February 2019. Inclusion criteria were symptomatic flexible flatfoot in children with failed non operative treatment. During the study period, 22 feet of 20 patients with symptomatic flatfoot underwent lateral calcaneal lengthening osteotomy. All patients met the inclusion criteria and were available for clinical and radiological follow-up. The percentage female were (55%)–male were (45%), The mean age at time of surgery was 10.33 years old (7 – 17 years old) and their mean follow up period was 15months.The mean functional American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score had improved from 68.9 (58-78) preoperatively to 96.09 (86-100) postoperatively at last follow up (P value < 0.001) using paired t-test as a significance test for evaluation of pre and post-operative AOFAS score.The results of this study support the combination of lateral column lengthening and soft tissue reconstruction for treatment of PesPlano-valgus foot deformity, The adopted technique revealed satisfactory result both in children and adolescents