en تومور Tumor surgery پژوهشی Research Article <strong>Background</strong>: Reconstructing large bone defects after lower limb tumor resection remains a challenge in pediatric orthopedics. While osteoarticular allografts offer a biological solution, achieving stable fixation and union is crucial to minimize complications such as fractures and nonunions.&nbsp;<br> <strong>Objectives</strong>: We aimed to explore a novel, stabilized, dynamized nailing technique (SDNT) to enhance outcomes in pediatric patients undergoing tumor resection and reconstruction.<br> <strong>Methods</strong>: Between 2014 and 2024, 40 pediatric patients (Mean&plusmn;SD age: 11.85&plusmn;2.93 years) with malignant bone tumors (70.73% osteosarcoma, 24.39% Ewing sarcoma, 2.44% chondrosarcoma) underwent wide resection (&ge;2 cm margins) and reconstruction with fresh frozen osteoarticular allografts (FFOA) soaked in gentamicin. Fixation was achieved using SDNT, a modified intramedullary nailing (IMN) approach designed to promote union through controlled dynamization. Patients were followed for a Mean&plusmn;SD of 33.68&plusmn;20.58 months, with outcomes including union time, complications, and survival assessed via clinical and radiographic evaluations.<br> <strong>Results</strong>: The Mean&plusmn;SD union time was 9.71&plusmn;3.05 months. Complications occurred in 48.88% of patients, with delayed union (24.39%), infection (14.64%), and drop foot (4.88%) being the most common. Notably, no fractures occurred except for nail bending (2.44%). Survival was 70.73%, with a 29.27% mortality rate and 17.07% disease relapse. Metastasis affected 29.27% of patients, primarily in the lungs (26.83%).<br> <strong>Conclusion</strong>: SDNT with osteoarticular allografts offers a promising approach for pediatric lower limb tumor reconstruction, achieving a low fracture rate and effective bone union despite a high overall complication rate. These findings suggest SDNT may improve mechanical stability compared to traditional fixation methods, warranting further investigation. Pediatric bone tumors, Osteoarticular allograft, Stabilized dynamized nailing, Intramedullary nailing (IMN), Lower limb reconstruction, Tumor resection, Osteosarcoma, Ewing sarcoma, Bone :union:, Fresh frozen allograft, Gentamicin-soaked allograft 213 220 http://jros.iums.ac.ir/browse.php?a_code=A-10-1846-2&slc_lang=en&sid=1 Sam Aliliu Sami samhaji@yahoo.com 10031947532846008351 10031947532846008351 No Department of Orthopedics, Bone and Joint Reconstruction Research Center, School of Medicine, Iran University of Medical Sciences, Tehran, Iran. Khalil Kargar khalilkargar63@gmail.com 10031947532846008352 10031947532846008352 No Department of Orthopedics, Bone and Joint Reconstruction Research Center, School of Medicine, Iran University of Medical Sciences, Tehran, Iran. Roshanak Shams shams.rosha.86@gmail.com 10031947532846008353 10031947532846008353 No Department of Orthopedics, Bone and Joint Reconstruction Research Center, School of Medicine, Iran University of Medical Sciences, Tehran, Iran. Bushra Zareie shafabushra@gmail.com 10031947532846008354 10031947532846008354 No Department of Orthopedics, Bone and Joint Reconstruction Research Center, School of Medicine, Iran University of Medical Sciences, Tehran, Iran. shahabaldin Beheshti Fard shahab.dr71@gmail.com 10031947532846008356 10031947532846008356 No Bone and Joint Reconstruction Research Center, Department of Orthopedics, School of Medicine, Iran University of Medical Sciences, Tehran, Iran Amin Hamidzadehkhiavi drahkh2000@gmail.com 10031947532846008355 10031947532846008355 Yes Department of Orthopedics, Bone and Joint Reconstruction Research Center, School of Medicine, Iran University of Medical Sciences, Tehran, Iran.