e22505 Background: Pediatric, adolescent and young adult (AYA) patients with a diagnosis of osteosarcoma require surgical resection for local control in addition to adjuvant chemotherapy. Limb salvage surgery (LSS) has long been established as the standard of care. Pediatric and AYA patients with sarcoma are know to have an increased risk of VTE however thromboprophylaxis is not routinely used in the pediatric oncology patients. Here we review our experience over a 5 year period with patients up to 21 years diagnosed with osteosarcoma of the lower extremity treated with LSS, amputation or rotationplasty as local control and the development of VTE. Methods: A retrospective chart review was completed of patients up to 21 years of age treated for osteosarcoma of the lower extremity between January 2011 and December 2016 at our institutions. Those that underwent surgical resection of the tumor were included. Data regarding age, type of surgical procedure, the presence of a venous thrombosis, the time from diagnosis and surgery to detection of VTE and the use of anticoagulants was collected Results: 18 patients were identified: median age 14 year (6-21), 8 patients had LSS, 4 underwent rotationplasty and 6 had an amputation. Seven VTE were identified, 5 occurred in patients receiving LSS, 2 in a patient post rotationplasty and 0 in the amputation group. 6 of the 7 VTE occurred within the upper venous system, associated with the central venous line. Conclusions: In pediatric AYA patients being treated for lower limb osteosarcoma, the incidence of VTE was significantly increased for those undergoing LSS (63%) and rotationplasty (50%) compared to those receiving amputation (0%). While the population reviewed is small, based on these findings, prophylactic anticoagulation for patients with osteosarcoma, especially those patients undergoing LSS and rotationplasty should be considered beyond the immediate perioperative period. Larger prospective studies are needed to determine the risk of VTE and risks and benefits of prophylactic anticoagulation in this patient population.