BackgroundOsteosarcoma and Ewing sarcoma are more common diagnoses in preadolescent and adolescent children compared with the adult population. A greater percentage of patients are treated with limb salvage and reconstruction using modular tumor endoprostheses. Implant-to-bone fixation can be cemented or cementless. Cementless tumor endoprostheses rely on biologic osteointegration for implant stability, and chemotherapy during childhood and adolescence can disturb the bone turnover rate and reduce bone mineral density, which in turn may predispose patients with uncemented endoprostheses to a high rate of revision surgeries.Questions/purposes(1) What is the cumulative incidence of revision operations for any cause (wound dehiscence, periprosthetic fracture, hinge breakage, aseptic loosening, infection, local recurrence, implant removal, and amputation) of cementless tumor endoprostheses around the knee? (2) What is the cumulative incidence of aseptic loosening, periprosthetic fracture, hinge breakage, and infection, and what proportion of patients had other complications? (3) What was the mean limb length discrepancy (LLD) at the time of skeletal maturity? (4) What was the median Musculoskeletal Tumor Society (MSTS) score at most recent follow-up or just before implant removal/amputation if implant removal/amputation were performed?MethodsBetween 2008 and 2019, we treated 328 patients younger than 18 years for a primary bone sarcoma around the knee at our institution. Of those, 138 were treated with resection and reconstruction using two different types of modular tumor endoprostheses. During this period, our general indications for an endoprosthesis were patients who were candidates for an intraarticular resection of the distal femur or proximal tibia and who were at least 10 years of age. Uncemented fixation was always preferred. Cemented fixation was only done when intraoperative press-fitting of a cementless stem was not possible. Among uncemented implants, 26 patients died before completing 2 years of follow-up with intact implants and without further surgery, three were lost to follow-up before 2 years, and four patients received implants as a secondary salvage surgery after a failed primary biologic reconstruction with a vascularized fibular bone graft, leaving 94 patients for evaluation in this retrospective study. The mean age was 15 ± 2 years and the median (interquartile range) follow-up duration was 51 months (39 to 74). We did a competing risks analysis to tally cumulative incidence of all-cause revision procedures and cumulative incidence of aseptic loosening, periprosthetic fracture, hinge breakage, and infection. Other complications, including wound dehiscence, local recurrence, and stem breakage, were characterized descriptively and ascertained by review of electronic records of a longitudinally maintained institutional database by the treating surgeons. LLD was measured by serial clinical assessments and CT scans, starting since primary salvage surgery and until the latest follow-up of eve...

Background: The histological response to neoadjuvant chemotherapy (NAC) in pediatric patients with Ewing sarcoma family of tumors (ESFT) can predict the disease-free survival. Therefore, a noninvasive method for response assessment is needed. Using the currently established imaging modalities, mass reduction does not always correlate with the percentage of necrosis. Objective: To determine the potential role of 18 fluorine-labeled fluoro-2-deoxyglucose positron emission tomography (18 F-FDG PET) metabolic parameters in the prediction of poor histological response to NAC in pediatric patients with ESFT. Methods: Thirty-six patients who were treated with NAC and surgery at the Children's Cancer Hospital, Egypt, were prospectively included in this study. All patients underwent two studies; a PET/CT study before NAC and another one after NAC completion. Metabolic PET parameters were measured in each study. The ability of each of these parameters, their pretreatment and pre-local control values, as well as the percentage reduction between their pretreatment and pre-local control values, were evaluated to differentiate between good and poor responders using the histological response as a standard reference.

Aim: Scarce data assessing the real value of whole lung irradiation (WLI) in Ewing’s sarcoma (ES) with lung-only metastasis, with published conflicting results. We studied the impact of WLI in a homogenous pediatric population. Materials & methods: Retrospective study evaluating the survival outcomes of WLI in these patients. Results: Out of 163 metastatic ES; 41 patients were eligible for WLI. 30 patients (73.1%) received WLI (+ve) while 11 patients (26.8%) did not receive WLI (-ve). Five-year event-free survival was statistically significant in WLI (+ve). Five-year pulmonary relapse-free survival showed trend for improvement with WLI (+ve), while 5-year overall survival was not statistically significant between the two arms. Conclusion: WLI added significantly to the long term clinical outcome of metastatic ES patients, with no irreversible toxicity.

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