Application of core biopsy in revision arthroplasty for deep infection.

A preliminary core biopsy was performed in 168 consecutive joint arthroplasties (141 hips and 27 knees) before revision for suspected deep infection. Data of the core biopsy and subsequent revision procedures were available for 159 cases. Biopsies and revisions were all performed by one surgeon, and the exchange procedures were all undertaken in an ultra clean air enclosure.

Tensile mechanical properties of polyacetal after one and six months' immersion in Ringer's solution.

The engineering polymer polyacetal (also known as polyoxymethylene) has a long history of clinical use including in the femoral component of the Freeman all-polymer knee replacement. The polymer is a promising material for novel applications including the femoral component of hip resurfacing prostheses. However, no work following the effect on mechanical properties of extended immersion in the physiological environment has been reported.

Effects of acetabular resurfacing component material and fixation on the strain distribution in the pelvis.

A 3D finite element (FE) model of an implanted pelvis was developed as part of a project investigating an all-polymer hip resurfacing design. The model was used to compare this novel design with a metal-on-metal design in current use and a metal-on-polymer design typical of early resurfacing implants. The model included forces representing the actions of 22 muscles as well as variable cancellous bone stiffness and variable cortical shell thickness.

Acetabular morphology and resurfacing design.

The bony surfaces of 18 archaeological hemipelves were scanned using a 3D laser surface scanner and CyDir software on a Silicon Graphics workstation. The acetabular area was selected and point data from the approximately spherical bone surface saved. These data were input to a MATLAB routine that calculated the radius and centre of the best-fit sphere.