Implant-cement debonding at the knee has been reported previously [1]. The strength of the mechanical interlock of bone cement on to an implant surface can be associated with both bone cement and implant related factors. In addition to implant surface profile, sub-optimal mixing temperatures and waiting times prior to cement application may weaken the strength of the interlock. The study aimed to investigate the influence of bone cement related factors such as mixing temperature, viscosity, and the mixing and waiting times prior to application, in combination with implant surface roughness, on the tensile strength at the interface.Introduction
Aims
Fatigue and wear at the head/stem modular junction of large diameter total hip replacements can be exacerbated as a result of the increase in frictional torque. In this investigation, a large diameter metal on metal THR was tested on a rig designed to recreate the toggling motion at the head/stem junction. Post-test analyses are conducted to look for evidence of mechanical and corrosive damage.Introduction
Aims
Varus alignment of the knee is common in patients undergoing unicondylar knee replacement. To 56 patients (31 varus, 25 normal) were evaluated through CT imaging. Images were segmented to create 3D models and aligned to a tri-spherical plane (centres of spheres fitted to the femoral head and the medial and lateral flexion facets). 30 key co-ordinates were recorded per specimen to define the important axes, angles and shapes (e.g. spheres to define flexion and extension facet surfaces) that describe the femoral condylar geometry using in-house software. The points were then projected in sagittal, coronal and transverse planes. Standardised distance and angular measurements were then carried out between the points and the differences between the morphology of normal and varus knee summarised. For the varus knee group, trends were investigated that could be related to the magnitude of varus deformity.Introduction:
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