Comparison of Different Materials in the Same-Sized Cemented Stems on Periprosthetic Fractures in Bone Models

Objective: The increasing number of aging patients with total hip arthroplasties (THA) causes an increased incidence of periprosthetic fractures (PPF). The study aimed to evaluate the impacts of two different materials in the same-sized cemented stems on PPF in bone models. Methods: This study compared the maximum rotational torque leading to PPF when stems made of cobalt-chromium-molybdenum (Co-Cr-Mo) alloy and stainless use steel (SUS) were implanted using simulated bone models (Sawbones, 3403). The maximum destruction torque was compared statistically for each material (Co-Cr-Mo alloy vs. SUS stainless steel) in this model, and fracture patterns were examined. Results: The PPF occurred with a spiral propagation from the proximal femur towards the diaphysis, with breakage occurring near the distal end of the stem. There were no significant differences in the destruction torque values between the Co-Cr-Mo alloy (103.0 ± 14.9 Nm) and SUS (98.7 ± 15.1 Nm) samples (p = 0.575). The fractures using the bone models exhibited similar patterns in all specimens, resembling clinical PPF fracture types clinically, specifically Vancouver classification B2. Conclusions: The comparison of the maximum destruction torques of the Co-Cr-Mo alloy and SUS cemented stems in simulating PPF showed no significant differences. The results suggest that the materials of the cemented stems might not significantly affect the occurrence of PPF in THA.