Computer-assisted osteodensitometry following total hip arthroplasty

Several factors, including polyethylene wear debris, implant micromotion and stress shielding, can cause bone loss and fixation failure following total hip arthroplasty. Various techniques have been utilized in an effort to detect bone density loss in vivo with varying success. Quantitative computed tomography (qCT)-assisted osteodensitometry has been shown to be useful in assessing the in vivo structural bone changes after total hip arthroplasty. It has high resolution, accuracy and reproducibility, making it a useful tool for research purposes. qCT osteodensitometry is able to differentiate between cortical and cancellous bone structures, and to assess the bone/implant interface. It provides valuable information about the pattern of stress shielding that occurs around the prosthesis. qCT-assisted osteodensitometry can show early bony changes, which may provide information about the quality of implant fixation and surrounding bone adaptation. In conjunction with finite-elements analysis, qCT is able to generate accurate patient-specific meshes on which to model implants and their effect on bone remodeling. This technology can be useful in order to predict bone remodeling and quality of implant fixation using prostheses with different design and/or biomaterials. In future, this tool could be used for preclinical validation of new implants before their introduction in the marketplace.