Development of a dynamic tensioner device for joint gap stiffness during knee arthroplasty.

Wium, Daniel Jacobus (2018-03)

Thesis (MEng)--Stellenbosch University, 2018.

Thesis

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.

AFRIKAANSE OPSOMMING: Korrekte knie-belyning en sagteweefsel-spanning kan die funksie van ‘n knie verbeter en die duursaamheid van ‘n prostese verleng na afloop van ‘n knievervangingsoperasie. Knie-belyning en sagteweefsel-spanning hou verband met die kniegewrig-gaping-styfheid. Die kniegewrig-gaping-styfheid is ‘n funksie van die spanning in die knieligamente en ‘n funksie van die afstand tussen die femur en die tibia. Die kniegewrig-gaping-styfheid word tipies geassesseer met die knie in 0° en 90° fleksie. Daar bestaan nog nie riglyne om die spanning in die knieligamente óf die afstand tussen die femur en die tibia tussen hierdie hoeke van knie-fleksie te bepaal nie. Die doel van hierdie studie is om ‘n konsepbewys te lewer vir ‘n nuwe dinamiese knietoestel wat die gewrig-gaping-styfheid kan meet by alle hoeke van knie-fleksie tussen 0° en 90° tydens ‘n halwe knievervangingsoperasie. In hierdie studie is twee prototipes ontwikkel wat die kniegewrig-gaping-styfheid kwantifiseer in terme van die spanning in die knieligamente en die afstand tussen die femur en die tibia. Die prototipes kan óf die tibiofemorale krag meet met ‘n konstante gaping-afstand óf die gaping-afstand meet met ‘n konstante tibiofemorale krag. Drie in-vitro toetse, waartydens die gewrig-gaping-styfheid van kadawer knieë gemeet is, is uitgevoer. Die gewrig-gaping-styfheid is gemeet in die oorspronklik knie met die ongeskonde femur en ook in die knie waarby prostetiese femurs ingevoeg is. Die in-vitro toetse het insiggewende resultate rakende die styfheid van die knie, die geometrie van die knie ruimte, en die geometrie van die kontakoppervlakte van die bene in óf die laterale óf mediale kompartemente gelewer. Die knietoestelle assesseer die uitkoms van sagteweefsel-balansering tydens ‘n knievervangingsoperasie op ‘n kwantitatiewe vlak wat met resultate verkry na ‘n operasie gekorreleer kan word. Dit mag lei tot die standaardisering van sagteweefsel-balansering. Die knietoestelle in hierdie studie lewer ‘n konsep vir die ontwerp van ‘n dinamiese knietoestel wat in ‘n kliniese halwe knievervangingsoperasie en in ‘n kliniese totale knievervangingsoperasie gebruik kan word.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/103784
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