Biomechanical comparison of periprosthetic femoral fracture risk in the Exeter V40, CPT and DePuy C-stem in a Sawbone model

Abstract The increasing use of orthopaedic total hip replacement implants has led to a consequent rise in the incidence of associated periprosthetic fractures (PPF). Analysis of the national joint registry data showed the choice of cemented hip stem influenced the risk of a PPF occurring. However, the effect of implant design in relation to the risk of PPF has not been investigated. The main objective was to compare the biomechanics of PPF’s as a failure of the Exeter V40, CPT and DePuy C-stem stems in a composite Sawbone model to identify if a difference in the risk of fracture exists between them. 26 Sawbones were divided into three groups, cemented with either the Stryker Exeter, Zimmer CPT or DePuy C-stem and then torqued to fracture. When compared to the Exeter, the CPT and C-stem implanted Sawbone models would sustain PPF’s at statically significant lower rotation to failure (20.1° and 26.7° versus 33.6°, p The differences in stem design mean higher stress at the critical point of failure in the CPT implanted femur compared to the Exeter and DePuy, which is likely the reason behind the observed increased risk of PPF with the CPT implant.