Abstract
AIMS: The management of Paprosky IIIB acetabular bone defect is challenging in revision total hip arthroplasty. Custom-made acetabular components (CMAC) have been increasingly used in recent years. However, the iliac fixed flange of CMAC is still a mechanically weak area, where nonuniform stress distribution and micromotion may cause prosthesis failure. This study aimed to enhance the iliac fixation effect by enhancing the structure of the iliac flange or using a quadri-flange CMAC. The biomechanical performance was compared to provide a theoretical basis for clinical application. METHODS: The inhomogeneous finite element analysis (FEA) model was reconstructed according to the Paprosky IIIB acetabular defect. The biomechanical performance of enhanced triflanged and quadri-flange CMAC was evaluated according to the peak stress and the Von Mises stress distribution under routine conditions. The relative micromotion between the pelvis and prosthesis was analyzed to assess the stability of the implant. RESULTS: The peak stresses of the enhanced triflanged and quadri-flange CMAC were 126.90 and 140.70 MPa under gait cycle, respectively. The stress distribution in the enhanced triflanged CMAC was more uniform. In contrast, nonuniform stress distribution and larger high-stress concentration regions were found in the quadri-flange CMAC, especially in the screw contact sites between the screw and superolateral bone of the ilium. The results of micromotion showed that there was a larger proportion of units with > 28 μm in the quadri-flange CMAC (15%), while the enhanced triflanged CMAC structure had a smaller ratio (8%). CONCLUSION: The enhanced triflanged CMAC has better stress, stress distribution, and micromotion than quadri-flange CMAC in this model. In cases where both prostheses are suitable for use, the enhanced triflanged CMAC is more highly recommended.