Novel customized 3D-printed prosthesis for complex infected bone defects: a clinical case series

Abstract

Infected bone defects, especially irregular or long-segment defects, pose great clinical challenges. By performing bone defect reconstruction on patients with complex infected bone defects admitted to our hospital, this study explores the clinical efficacy of a novel customized 3D prosthesis combined with the induced membrane technique in the treatment of complex infected bone defects and the feasibility of relevant prosthesis design strategies. It also discusses its positive effects on infection control and improvement of patients’ quality of life. (1) Measurement and Design : A 256-slice spiral CT was used to perform thin-layer scanning (layer thickness 1 mm) of the patient’s infected bone defect area and the corresponding healthy side. The data were saved in DICOM format and reconstructed into 3D using Mimics software. Using the healthy side as a template and applying the mirror principle, the data from the defect area were matched with those from the healthy side. First, the corresponding anatomical landmark points were identified, and a digital model of the implant was designed, with the debrided normal bone tissue serving as the boundary and an osteotomy plane of 5 mm depth. The model was saved in STL format. The STL file was imported into Materialise’s 3-matic software, and the model was designed starting from the osteotomy surface to facilitate mold testing. (2) Printing and Surgical Simulation : The scanned CT data was sent to Dimension (Xi’an) Biomedical Technology Co., Ltd. Engineers employed computer-aided technology to eliminate metallic artifacts from the bone prosthesis. Based on the patient’s specific bone defect location, anatomical position, and characteristics of the surrounding bone tissue, they designed a prosthesis tailored to the bone defect. Using 3D printing technology, the customized porous titanium alloy prosthesis was then simulated and printed. (3) Application and Indicator Analysis : This study summarizes and analyzes the 3D prosthesis design process for four patients with infected femoral osteomyelitis complicated by bone defects who received personalized 3D-printed porous titanium alloy prostheses at our hospital between May 2023 and May 2025. Treatment was conducted in two phases: In the first phase, following the induced membrane technique protocol, all four patients underwent thorough debridement followed by bone cement placement. In the second phase, the personalized 3D-printed prostheses were used to reconstruct and repair the infected bone defects. Postoperative follow-ups were performed at 1, 3, 6, and 12 months, with X-ray and CT examinations used to assess the integration of the reconstructed prostheses with the bone ends, evaluating the clinical efficacy of personalized 3D-printed prostheses in the repair and reconstruction of complex infectious bone defects. A 3D-printed porous titanium alloy prosthesis was adopted, with a porosity of approximately 70%, pore size ranging from 850 to 1000 μm, filament diameter of the porous structure between 320 and 420 μm, and an elastic modulus of about 2.4 GPa. Personalized designs including interfacial porous structures, solid truss structures, biological short intramedullary nails, integrated wing plates, penetrating fixation nail holes, replaceable joints and compatibility with conventional steel plates were adopted for infected bone defects at different anatomical sites. The prostheses were tightly bonded to the fractured bone ends, achieving successful repair and reconstruction in four patients with complex infected bone defects.The specificity of the induced membrane provides a microenvironment for bone biological reconstruction, and personalized 3D-printed prostheses achieve mechanical reconstruction of bone defects while preserving the full function of the affected limb. The combination of the two offers a feasible treatment scheme for the reconstruction and repair of complex infected bone defects.All 4 patients with infected bone defects in this study (with an average bone defect length of 113.86 mm) achieved reconstruction of complex infected bone defects. During the follow-up over the past year, 3 patients exhibited excellent limb function, and the remaining patient also had satisfactory function of the affected limb at the 8-month postoperative follow-up. For the 3 patients, X-ray and CT examinations conducted at 1, 3, 6 and 12 months after surgery revealed favorable osseointegration at the prosthesis-bone interface. As the other patient had not completed one year postoperatively, X-ray and CT scans at 6 months after surgery showed callus formation at the prosthesis-bone interface and stable fixation of the prosthesis. The individually designed 3D-printed porous titanium alloy prosthesis can anatomically and mechanically stabilize the repair and reconstruction of complex bone defects after induced membrane technique for infected bone defects. It preserves the complete limb function of patients, avoids the dilemmas such as insufficient autologous bone graft sources, pin tract infection risks after surgery with traditional external fixation brackets and difficulties in clinical nursing, reduces patients’ bedridden time and improves their quality of life. This approach expands the prosthesis design strategies and feasible treatment schemes for repairing complex infected bone defects in clinical practice, and has achieved satisfactory clinical therapeutic effects.