Patient-Specific 3D-Printed Prosthetic Reconstruction of Proximal Tibial Bone Defects: A Retrospective Case Series
This retrospective case series of 13 patients demonstrates that patient-specific 3D-printed prostheses are a feasible and stable reconstructive option for complex proximal tibial bone defects, significantly improving functional outcomes at 12 months with no mechanical failures, though larger long-term studies are needed to confirm superiority over conventional methods.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
The lower leg is a complex machine where bone, muscle, and tendon work together to bear weight and allow movement. When a tumor grows in the upper part of the shinbone, known as the proximal tibia, removing it often leaves a difficult gap. Surgeons must cut away the diseased bone, but this removal can also damage the attachment points for the knee's extensor mechanism—the system of tendons and ligaments that straightens the leg. Traditional replacements often struggle to fit these irregular gaps perfectly or to reattach the soft tissues needed for a stable knee. The goal of modern reconstruction is not just to fill the hole with metal, but to restore a functional unit where the bone, the implant, and the surrounding soft tissues work together as one.
A team of researchers at Xinjiang Medical University explored a new way to solve this problem by using patient-specific 3D-printed prostheses. Instead of using a standard, off-the-shelf metal implant, they created a custom device for each patient based on detailed scans of their own body. The process began with computer models built from magnetic resonance imaging and computed tomography scans, which allowed surgeons and engineers to design a replacement that matched the exact shape of the remaining bone and the specific defects left by the tumor. These custom prostheses were not just solid blocks of metal; they were engineered with tiny holes and porous surfaces to encourage the patient's own bone to grow into the implant over time. Crucially, the design included small holes for sutures, allowing surgeons to reattach the patellar tendon and other soft tissues directly to the metal, restoring the mechanical function of the knee.
The study followed thirteen patients who underwent this procedure between January and June 2025. The group included children and adults with various types of bone tumors, such as Ewing sarcoma, chondrosarcoma, and osteosarcoma. For the younger patients who were still growing, the team incorporated a special expandable section into the middle of the prosthesis, designed to allow for future lengthening as the child grew. The surgery involved removing the tumor and implanting the custom device, which was secured with screws and a supplementary plate to ensure stability. The researchers tracked the patients for at least one year to see how well the implants held up and how the patients' ability to walk and move improved.
The results showed that the custom approach was feasible and stable in the short term. After an average of thirteen months, every single prosthesis remained in place without breaking, loosening, or requiring removal. None of the patients experienced a fracture of the implant or a failure of the connection between the metal and the bone. While two patients did face minor complications—one with a wound that healed slowly and another with a temporary knee dislocation after a fall—neither required the prosthesis to be taken out or replaced. Most importantly, the patients' functional scores, which measure pain, walking ability, and emotional well-being, improved significantly. The median score rose from fourteen points before surgery to twenty-six points a year later, indicating a strong return to daily activity. By the twelve-month mark, all thirteen patients could walk without assistance, had no significant lag in straightening their knees, and reported little to no pain during normal activities.
Despite these positive early signs, the researchers caution that this is not yet a proven superior method compared to traditional options. The study was small, involved only one hospital, and followed patients for a relatively short time. The team noted that while the implants held firm, they could not yet confirm that bone had fully grown into the porous surfaces, as that would require longer observation or different types of testing. They also emphasized that for children, the long-term success of the expandable components remains unknown, as no patient had yet needed to use the lengthening feature. The findings suggest that patient-specific 3D-printed prostheses offer a promising tool for complex cases where standard implants might not fit or where soft-tissue reconstruction is difficult, but larger studies with longer follow-up are needed to determine if this approach is better than existing methods for everyone.
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