Additively manufactured shape-morphing implants for the treatment of acetabular defects

Acetabular defects pose significant challenges in orthopedic surgery, particularly in revision total hip arthroplasty (THA). Here, we design, additively manufacture, and evaluate shape-morphing porous implants with kinematic structures to address these defects. Three defect types were examined using synthetic hemipelvis models: posterior wall, cranial-posterior combination, and central-posterior defects. The implants were secured with screws and bone cement, and their surface conformity was assessed through micro computed tomography (µCT). Biomechanical performance was evaluated under quasi-static compression and cyclic loading conditions. Results demonstrated high surface conformity of the flexible mesh across all defect types, with minimal differences from healthy acetabula (< 10 mm). The mesh implants exhibited strong load-bearing capacity, with failures occurring only in the pubic region of the hemipelvis, while both the implants and mesh-cement interfaces remained intact. The implants withstood cyclic loading simulating half the body weight of a 80 kg patient for more than 1,000,000 loading cycles with no evidence of fatigue failure, further confirming their durability. These findings suggest that the flexible mesh implant provides a potential solution for complex acetabular defects, offering anatomical conformity and mechanical stability, even in cases where conventional mesh grafts might be inadequate. Future studies, including cadaveric testing and clinical trials, are necessary to further validate these results in (pre-)clinical settings. STATEMENT OF SIGNIFICANCE: This study addresses the need for adaptable solutions to complex acetabular defects in revision total hip arthroplasty (THA). Traditional implants struggle to conform to severe bone loss and irregular geometries, risking suboptimal fit, and implant migration. We introduce a 3D-printed, shape-morphing porous implant with kinematic structures, offering high anatomical conformity, mechanical robustness, and support for bone graft integration. Combining the adaptability of patient-specific implants with the efficiency of standard designs, this implant reduces lead times while enabling a tailored fit. This innovative approach provides a reliable solution for managing complex defects, addressing limitations of conventional implants, and improving outcomes in orthopedic reconstruction.