Browsing by Author "Wium, Daniel Jacobus"

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    Development of a dynamic tensioner device for joint gap stiffness during knee arthroplasty.
    (Stellenbosch : Stellenbosch University, 2018-03) Wium, Daniel Jacobus; Muller, Jacobus Hendrik; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    ENGLISH ABSTRACT: Correct knee alignment and soft tissue tensions can relieve pain, improve knee function and increase the durability of the prosthesis after knee arthroplasty. Knee alignment and soft tissue tensions relate to the joint gap stiffness. The joint gap stiffness is a measure of the tension in the ligaments and the distance between the femur and the tibia. The joint gap stiffness of the knee is typically assessed with the knee in 0° and 90° knee flexion. Guidelines for the tension of the ligaments and the distance between the femur and the tibia have not yet been defined for knee flexion between these angles. The aim of this study is to provide a proof of concept for a dynamic knee tensioning device capable of measuring the joint gap stiffness at all angles between 0° and 90° knee flexion during unicompartmental knee arthroplasty. In this study, two prototypes were developed which quantify the joint gap stiffness in terms of the tibiofemoral force and the gap distance. The prototypes are capable of either measuring the tibiofemoral force at a constant gap distance or measuring the gap distance at a constant distraction force. Three in-vitro tests were conducted in which the prototypes were used to measure the joint gap stiffness of cadaver knees. The joint gap stiffness was measured in the native knee (intact femur) as well as in the resurfaced knee. The results have proven that the knee tensioners developed in this study can provide insight into certain characteristics of the knee, which include knee stiffness, spatial geometry, and articulating surface geometry of either the medial or the lateral compartments. The knee tensioners assess the outcome of soft tissue balancing on a quantitative level which can be correlated to postoperative results. This may lead to the standardisation of soft tissue balancing. The knee tensioners developed in this study provide a concept for the design of a dynamic knee tensioner to be used during clinical unicompartmental knee arthroplasty as well as in clinical total knee arthroplasty.