Quantitative Assessment of Polyethylene Component Position in a Mobile-Bearing Prosthetic Knee,Using a Single Radiograph |
| |
Authors: | ADRIAN B. LIGGINS PhD PEng W. ROBERT HARDIE MD CAND-ING FRANK WEBER EUR ING J. BRYAN FINLAY PhD PEng |
| |
Affiliation: | 1. Gait Analysis Laboratory, Shriners Hospital for Children , 3551 North Broad Street, Philadelphia, Pennsylvania, 19140, USA;2. Department of Urology , London Health Sciences Centre , Victoria Campus, London, Ontario, Canada;3. Department of Orthopaedics , Division of Surgery, London Health Sciences Centre , University Campus, London, Ontario, Canada;4. Department of Medical Biophysics , University of Western Ontario , London, Ontario, Canada |
| |
Abstract: | Rationale and Objectives. To reduce tibio-femoral misalignment, the polyethylene bearing-component of a new knee prosthesis was allowed limited motion on the underlying metallic component. The object of the work presented here was to develop a suitable radiographic technique for quantifying the in-vivo position of the bearing. By collecting these data at discrete flexion angles, the functional operation of the prosthesis could be determined Methods. The known geometries between landmarks on the two components were used to produce algorithms for reconstructing their spatial positions from a single radiograph. A custom-designed computer program utilized these algorithms to determine the relative translation and rotation of the polyethylene component Results. This technique produced typical errors of 0.54 mm translation and 0.56° rotation between the polyethylene component and the underlying metallic component Conclusions. A practical method has been developed for assessing mobile-bearing motion, in vivo. This method can be applied to other prosthetic devices, or combinations of components, once the requirement for identifiable landmarks has been addressedClinical Relevance. Skeletal and soft-tissue changes in the pathological knee may produce abnormal rotations and translations in the transverse tibial plane. This technique is intended both to validate the design philosophy of a mobile-bearing prosthesis and to provide additional data on any pathological motions, which will have implications for future prosthetic designs. |
| |
Keywords: | Knee prosthesis three-dimensional measurement single X-ray |
|
|