[Acetabulum deformations after implantation of a cemented cup with or without metal-back component. An in vitro comparative study of monopodal load].

PURPOSE OF THE STUDY

The purpose of this study was to find a biomechanical explanation for a clinical failure of metal backed acetabular components. Periacetabular deformations were measured on fresh cadaver bones equipped with strain-gauge rosettes.

MATERIAL AND METHODS

Two skeletons, including pelvic bone, the two last lumbar vertebrae, and both femurs were maintained in unipodal equilibrium using metallic cables for muscle simulation. Loads were applied up to 700 N the approximating average body weight. A comparative study of periacetabular deformations was performed: right sides of each pelvic bone were implanted with conventional cemented implants, and left sides with metal backed cemented implants of same diameter and size.

RESULTS

Significant differences were noted: whereas no modification was brought by implantation of conventional cemented sockets, periacetabular deformations were reduced and smoothed after implantation of cemented metal backed implants. Such results are in agreement with recently published data obtained, using the finite element analysis method.

DISCUSSION

A study of pelvic ring and acetabular walls displacement was performed, but the authors couldn't find any clinical relevance to this biomechanical study.