Marieke De Vaal

(1) Background: Megaprosthetic reconstruction of the knee is frequently required in limb salvage surgery for oncologic indications and in complex revision arthroplasty. The Modular Universal Tumor and Revision System (MUTARS) Total Knee prosthesis is widely used in these situations. The aim of this study was to evaluate revision-free implant survival following MUTARS Total Knee implantation and to compare outcomes between primary implantation and use as a conversion procedure after failure of a previous knee prosthesis. (2) Methods: A retrospective cohort study was performed including 36 patients who underwent MUTARS Total Knee implantation at a single institution. Patients were stratified into primary implantation (n = 24) and conversion after failed prosthesis (n = 12). The primary endpoint was time to first revision. (3) Results: Overall revision-free survival was 51.6% at 2 years and 29.3% at 5 years. No significant difference in revision-free survival was observed between primary implantation and conversion procedures (log-rank p = 0.67). When mechanical failure (Henderson type III) was considered as the sole endpoint, implant survival was substantially higher, with 88.3% survival at 2 years and 57.2% at 5 years. Infection-related implant survival was 72.0% at both 2 and 5 years. Secondary amputation was required in 7 of 36 patients (19.4%), with a higher proportion observed in the primary implantation group (25.0% vs. 8.3%). Most amputations occurred within the early postoperative period. (4) Conclusions: MUTARS Total Knee implantation is associated with a substantial revision burden; however, conversion after failed prosthesis did not result in inferior revision-free survival compared with primary implantation. Endpoint-specific analyses demonstrate that biological complications, particularly infection, represent the dominant drivers of early failure.

(1) Background: Pelvic osteosarcoma accounts for a small proportion of osteosarcoma cases but is associated with significantly poorer outcomes than extremity tumors. This study evaluates contemporary survival outcomes and prognostic factors in a single-center cohort. (2) Methods: We retrospectively analyzed 56 patients with primary pelvic osteosarcoma treated between 2006 and 2019. Demographic characteristics, surgical margins, adjuvant therapies, local recurrence, metastasis, survival outcomes and the Musculoskeletal Tumor Society (MSTS) Score were assessed. Kaplan–Meier analysis was performed for overall survival (OS), including subgroup analyses by age and Enneking classification. (3) Results: Median age at surgery was 24 years. R0 margins were achieved in 96.4% of cases. OS at 1, 3, and 5 years was 69%, 54%, and 48%, respectively. Younger patients (≤25 years) showed significantly improved 5-year OS (68%) compared with older groups. Enneking classification showed limited prognostic discrimination. Metastatic disease at any time strongly predicted inferior survival (5-year OS 30% vs. 66%). The mean MSTS score one year after operation was 14.1 points. Functional outcome showed marked variability and was strongly influenced by patient age, extent of resection, reconstruction strategy, and postoperative complications. Younger patients and those undergoing limited or non-acetabular reconstructions achieved superior functional results, whereas complex endoprosthetic reconstructions and revision-requiring complications were associated with reduced MSTS scores. (4) Conclusions: Pelvic osteosarcoma continues to be associated with substantial morbidity and mortality. Younger age and absence of metastatic disease are strong predictors of improved survival. Functional outcomes are typically moderate; further advances are needed to improve results.

Background: The reconstruction of diaphyseal bone defects following tumor resection offers various biological and endoprosthetic treatment options. The present study analyzes the impact of the fixation method (cemented; uncemented; with locking screw; without locking screw) of the diaphyseal implant on clinical outcomes. Factors such as patient age and weight as well as tumor type and location are also considered. Methods: This study included 39 patients who underwent intercalary endoprosthetic reconstruction of the humerus (n = 4); femur (n = 29); and tibia (n = 6) between 1998 and 2020. Prosthetic complications, fixation methods and the MSTS score for functional outcome were statistically analyzed using SPSS and R. Results: The event-free probability in the competing risk model was 61% (95% CI 43–74%) after one year and 11% (95% CI 3–28%) after five years. The complication rate in the patient cohort was 54%. Cementless prosthesis fixation was associated with a statistically significant better functional outcome. Additionally, higher body weight and older patient age were associated with lower MSTS scores. Conclusions: Patients requiring rapid remobilization or adjuvant radiation therapy may benefit more from diaphyseal implants compared to biological reconstructions. However, the complication and revision rates of diaphyseal implants are elevated. The chosen fixation method shows a statistically significant influence on functional outcome.

Background/Objectives: The World Health Organization’s (WHO) classification of tumors contains around 80 entities of soft tissue sarcomas (STSs). Currently, surgery is the standard treatment for patients with localized STS, but the adequacy of resection margins in soft tissue sarcomas (STSs) remains a topic of intense discussion. Methods: This single-center study retrospectively reviewed 203 patients with primary high-grade soft tissue sarcoma, including a follow-up period of at least 24 months. Patients with prior resection, secondary STS, metastasis at presentation, or those who required amputational surgery were excluded from the study. Patients were categorized based on their margin thickness: positive (n = 13, 6.4%), 0–1 mm (n = 67, 33.0%), 1–5 mm (n = 70, 34.5%), and >5 mm (n = 27, 13.3%). Results: A total of 64 out of 203 (31.5%) patients developed a local recurrence. The estimated 5-year local-recurrence-free survival (LRFS) was 11.5% (CI 4–25%) for positive margins, 58% (CI 51–64%) for margins 0–1 mm, 76% (CI 70–81%) for margins > 1–5 mm, and 93% (CI 88–98%) for margins > 5 mm. No local recurrences occurred in patients with margins > 5 mm and adjuvant radiotherapy. Margin status significantly influenced the development of distant metastasis and overall survival. Adjuvant radiotherapy improved both local control and overall survival. Conclusions: To minimize the risk of local recurrence (LR), a resection margin greater than 5 mm should be attained. When adjuvant radiotherapy is applied, the likelihood of LR decreases even more. In scenarios where preserving critical structures is essential, a resection margin of less than 5 mm can be acceptable for ensuring local control.

The combination of 3D printing and navigation promises improvements in surgical procedures and outcomes for complex bone tumor resection of the trunk, but its features have rarely been described in the literature. Five patients with trunk tumors were surgically treated in our institution using a combination of 3D printing and navigation. The main process includes segmentation, virtual modeling and build preparation, as well as quality assessment. Tumor resection was performed with navigated instruments. Preoperative planning supported clear margin multiplanar resections with intraoperatively adaptable real-time visualization of navigated instruments. The follow-up ranged from 2–15 months with a good functional result. The present results and the review of the current literature reflect the trend and the diverse applications of 3D printing in the medical field. 3D printing at hospital sites is often not standardized, but regulatory aspects may serve as disincentives. However, 3D printing has an increasing impact on precision medicine, and we are convinced that our process represents a valuable contribution in the context of patient-centered individual care.