von Witzleben Max, Liu Suihong, Sembdner Philipp, Holtzhausen Stefan, Blum Sophia Freya Ulrike, Lützner Jörg, Kilian David, Nimtschke Ute, Gelinsky Michael, Lode Anja, Bretschneider Henriette
Centre for Translational Bone, Joint and Soft Tissue Research, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.
Institute of Machine Elements and Machine Design, Faculty of Mechanical Engineering, Technische Universität Dresden, Dresden, Germany.
Mater Today Bio. 2025 May 13;32:101858. doi: 10.1016/j.mtbio.2025.101858. eCollection 2025 Jun.
Ideally, the combination of clinical imaging techniques with additive manufacturing processes enables the fabrication of patient-specific regenerative implants that precisely fit into the defect site, promoting native tissue restoration while gradually degrading. Osteochondral defects, affecting both cartilage and subchondral bone in joints are best visualized using magnetic resonance imaging (MRI). In this study, a workflow for computer-aided manufacturing of patient-specific osteochondral implants based on geometrical data obtained from MRI scans was evaluated in a clinically relevant setting. Artificial osteochondral defects were created in femoral condyles of human body donors and scanned with MRI. 'Computer-Aided Design' (CAD) models for bone and cartilage components served as basis for designing defect-specific trizonal implants consisting of (i) a bone, (ii) an interlocking, and (iii) a cartilage zone. These implants were fabricated using multi-channel 3D extrusion printing, using a calcium phosphate cement as a bone substitute and an alginate-based hydrogel as a cartilage substitute material - with both materials alternately printed in the interlocking zone. After fabrication, the constructs were implanted into the corresponding defects, and assessed for fit accuracy via clinical imaging. The entire process chain was successfully conducted under near-clinical conditions by an interdisciplinary team of engineers, radiologist and surgeons, during which critical points were identified. Due to the inherent resolution limitations of clinical MRI and extrusion-based 3D printing, inaccuracies in implant fitting occurred; strategies to address these challenges were identified by integrating design tolerances and applying minor intraoperative adjustments.
理想情况下，临床成像技术与增材制造工艺相结合，能够制造出适合患者的再生植入物，精确适配缺损部位，促进天然组织修复，同时逐渐降解。关节软骨和软骨下骨均受影响的骨软骨缺损，使用磁共振成像（MRI）能得到最佳可视化效果。在本研究中，在临床相关环境下评估了基于MRI扫描获得的几何数据进行计算机辅助制造患者特异性骨软骨植入物的工作流程。在人体供体的股骨髁上制造人工骨软骨缺损并进行MRI扫描。骨和软骨组件的“计算机辅助设计”（CAD）模型作为设计特定缺损的三区植入物的基础，该植入物由（i）骨、（ii）互锁区和（iii）软骨区组成。这些植入物采用多通道3D挤压打印制造，使用磷酸钙水泥作为骨替代物，藻酸盐基水凝胶作为软骨替代材料，两种材料在互锁区交替打印。制造完成后，将构建体植入相应缺损处，并通过临床成像评估适配精度。工程师、放射科医生和外科医生组成的跨学科团队在接近临床的条件下成功完成了整个流程链，并确定了关键点。由于临床MRI和基于挤压的3D打印固有的分辨率限制，植入物适配出现了不准确情况；通过整合设计公差和进行微小的术中调整，确定了应对这些挑战的策略。
