Motion investigation of a tendon graft's limbs using video tracing measurement

The biomechanical data derived from the standard tensile testing machines may not be able to show the relative motion of the graft limbs. This paper uses a digital video recording system to determine the relative motion of a looped tendon graft. Bovine common digital extensor tendon was used to create the looped graft and then the graft was passed through a tunnel in a foam block and fixed with an interference screw. The structure then was mounted in a testing machine and the tendon limbs were speckled just moments before test. The specimen was then loaded to failure at a rate of 20 mm/min. The load-displacement data of the graft structure was evaluated using the tensile test machine while the relative motion of the individual graft limbs was measured by capturing the movements of the tendon speckles by the camera. A relative motion was monitored between the two limbs of the loop tendon graft. The relative motion between the loop limbs up to the point of the graft failure was 0.412 mm.