title: Biomechanical evaluation of an adjustable patellar tendon bearing prosthesis.
abstract: The purpose of this study was to determine the relation between geometry of the patellar tendon (PT) insertion in the socket and the dynamic load transmitted through the PT, in a patellar tendon bearing (PTB) prosthesis. The dynamic load was measured by a specially constructed two-component load cell, which was mounted on the experimental prosthesis. Geometry of the PT insertion relative to the socket was altered by adjusting the location of the mounting frame-load cell assembly. Evaluation of performance of the prosthesis in the range of geometries investigated was made objectively by gait analysis of the patients. The latter was performed on a 10 m walkpath, including at halfway two forceplates, from which the foot-ground forces were recorded. Simultaneously, the PT forces on the prosthesis, as sensed by the load cell were monitored. Computer processing of the data included full analysis of the force-trace and the determination of criteria for optimization of the PT insertion. The resulting criteria were those which expressed minimization of abnormalities in the foot-ground forces of each patient, such as vertical and braking forces and their timings. The complete optimization procedure, which was undertaken for two below-knee male amputees, indicated the correct positioning of the PT insertion, actually taken in the final fitting procedure of the socket of the prosthesis.
mesh_terms: D000293:Adolescent; D000328:Adult; D000674:Amputees; D001696:Biomechanical Phenomena; D005684:Gait; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D010329:Patella / Q000503:physiopathology*; D013710:Tendons / Q000503:physiopathology*