Biomechanical properties of a titanium alloy pelvic prosthesis individually manufactured by 3D printing: a finite element analysis

Objective To evaluate the biomechanical properties of a titanium alloy pelvic prosthesis individually manufactured by 3D printing through finite element analysis. Methods A male patient with a huge chondrosarcoma at the right ilium was recruited for the present study who had been arranged for hemipelvectomy and artificial hemi-pelvic replacement. After the patient underwent CT and MRI examinations before operation, scope of tumor invasion around the ilium, surgical margins and plane for osteotomy were determined using the 3D image fusion technique. A finite element model of the pelvis of the patient was established on the basis of the defective area after pelvic osteotomy using computer aided design (CAD). After the finite element analysis, a customized titanium alloy pelvic prosthesis was manufactured using 3D printing technology. The software Abaqus was used to conduct finite element analysis of the model of the pelvic prosthesis manufactured by 3D printing. The von Mises stress, relative displacement and stress concentration point in the finite element model of the pelvis were measured and analyzed. Results The maximum von Mises stress in the titanium alloy pelvic prosthesis manufactured by 3D printing was 25.29 MPa, far smaller than the yield strength of titanium alloy (950 MPa). The stress concentration area was near the nail holes where the prosthesis and the sacrum were connected. The patient was able to walk without crutches 3 months post-surgery. After half a year, the implant was stable and the patient could perform normal activities. Conclusions The titanium alloy pelvic prosthesis individually manufactured by 3D printing based on the results of finite element analysis met the biomechanical requirements of a pelvis. The calculation results of finite element analysis were consistent with the postoperative follow-up outcomes of the patient. This method can provide biomechanical evidence for clinical application of 3D printing implants in orthopedics. Key words: Pelvis; Prostheses and implants; Finite element analysis; 3D printing technology