Force plates may be used for dynamic analyses of endoprostheses explantation procedures.

The number of hip and knee arthroplasty replacement surgeries is increasing steadily. In combination with demographic aging and the number of periprosthetic complications, this development has lead to the phenomenon where the need for revision surgery is rising. The problem is, that, while implantation procedures of hip arthroplasties are more or less standardized, explantation is a non-standardized task for experienced specialists, due to the unpredictability of the adequate loosening method. The surgeon often only gets to decide on which tools and methods may be applied to detach the prosthesis, only after getting access to the operation site. The time taken to detach the prosthesis is hardly predictable and mainly depends on the surgeons' skills. To gain objective data on the mechanics of explantation, new measurement methods are required. One technical base for studies on revision procedures are standard force plates, available in biomechanics laboratories.

Three-dimensional imaging of the fibrous microstructure of Achilles tendon entheses in Mus musculus.

The whole-organ, three-dimensional microstructure of murine Achilles tendon entheses was visualized with micro-computed tomography (microCT). Contrast-enhancement was achieved either by staining with phosphotungstic acid (PTA) or by a combination of cell-maceration, demineralization and critical-point drying with low tube voltages and propagation-based phase-contrast (fibrous structure scan). By PTA-staining, X-ray absorption of the enthesial soft tissues became sufficiently high to segment the tendon and measure cross-sectional areas along its course. With the fibrous structure scans, three-dimensional visualizations of the collagen fiber networks of complete entheses were obtained. The characteristic tissues of entheses were identified in the volume data. The tendon proper was marked as a segment manually. The fibers within the tendon were marked by thresholding. Tendon and fiber cross-sectional areas were measured. The measurements were compared between individuals and protocols for contrast-enhancement, using a spatial reference system within the three-dimensional enthesis. The usefulness of the method for investigations of the fibrous structure of collagenous tissues is demonstrated.