A Novel <scp>3D</scp> ‐Printed Strut‐Type Prosthesis Reconstructs the Hemicortical Defect After Distal Femur Parosteal Osteosarcoma Resection: The Mid‐Term Follow‐Up Outcome

ABSTRACT Background Parosteal osteosarcoma (PAOS) is a rare and low‐grade primary bone malignant tumor that typically occurs in the distal femur. Traditional reconstruction options for distal femur PAOS include distal femoral replacement (DFR), autografts, and allografts, but issues such as functional sacrifice, insufficient mechanical strength, and low bone union rate limit their further clinical application. 3D‐printed prosthesis, due to the matching shape of various bone defects, could be a novel strategy to reconstruct the hemicortical defect after distal femur PAOS tumor resection. In this study, we designed a 3D‐printed strut‐type prosthesis (3DPSP) to repair the hemicortical defect and evaluated the mid‐term effect in distal femur PAOS. Methods A retrospective analysis was conducted on patients diagnosed with PAOS at the distal femur between April 2018 and January 2021. Six patients received DFR and six patients received customized 3DPSP reconstruction. Clinical outcomes including oncology status, defect lengths, and ranges of motion of the knee, Musculoskeletal Tumor Society (MSTS) scores, and complications were recorded. X‐ray was performed to evaluate the position and stability of the prosthesis and T‐SMART was applied to assess the interface osteointegration between prosthesis and bone. Results A total of 12 patients were enrolled in this study with an average follow‐up of 42.1 ± 11.8 months, ranging from 22 to 59 months. In the 3DPSP group, the average operation time was 2.3 ± 0.4 h; the intraoperative blood loss was 175.0 ± 82.2 mL. The average range of motion of the knee was 0°–123° and the mean MSTS score was 28.3 ± 1.6. Compared to the DFR group, the 3DPSP group exhibited significantly less intraoperative blood loss and superior functional recovery. Conclusions In this study, we designed a novel 3DPSP to reconstruct the hemicortical defect after distal femur PAOS resection. The mid‐term follow‐up result demonstrated that this prosthesis could be an effective reconstruction option for distal femur PAOS patients because of the restored limb function and favorable bone‐prosthesis integration. Further observation of this novel prosthesis is needed.