ABSTRACT The aim of the study was to design a standardized mechanical test setup and a corresponding finite element analysis to assess the stability and strength of both patient‐specific and conventional implants for posterior wall acetabular fractures. Ten synthetic hemi‐pelves with posterior wall fractures were biomechanically tested with two types of implants: a patient‐specific implant (PSI) and a seven‐hole plate conventional implant. 3D‐printed guides ensured reproducibility. The models were tested using an Instron machine. The protocol involved 10,000 cyclic load cycles with static tests at 3200 N before and after to simulate early postoperative weightbearing conditions. Construct stiffness, stiffness over cyclic loading and fracture gapping were measured and compared. A finite element analysis was created with similar conditions to investigate stresses within the synthetic bone and fixation materials. The mechanical tests showed comparable stiffness for PSI (1.75 kN/mm) and the conventional implant (1.71 kN/mm, p = 0.47). Stability over 10,000 cycles was similar, and fracture gapping remained minimal (0.0–0.8 mm) without significant differences. No failure or plastic deformation occurred under 3200 N loading. Finite element analysis confirmed that von Mises stresses remained below the yield stress. This study introduces a reproducible workflow for biomechanical testing of acetabular fractures using synthetic bone models and 3D‐printed guides. It serves as a step‐by‐step guideline and standard reference for pelvic biomechanical testing. Both patient‐specific and conventional implants, using a seven‐hole plate construct with one or two screws through the plate in the fracture fragment, provide stable fixation for large posterior wall fragments.
Oldhoff et al. (Tue,) studied this question.