Development of a patient-specific unicompartmental knee replacement

Van der Merwe, Johan (2018-03)

Thesis (PhD)--Stellenbosch University, 2018.

Thesis

ENGLISH ABSTRACT: Patient-specific Unicompartmental Knee Replacements (UKRs) could potentially restore an Osteoarthritic (OA) knee closer to its pre-pathological state than off-the-shelf products. Nevertheless, the current state-of-the-art is still heavily reliant on a technician's interpretation and skill in order to reproduce healthy geometries. This dissertation therefore focused on developing a reliable, semi-automated approach to implant design. Inter-patient variability and inter- and intra-observer agreement and reliability was studied for a set of landmarks defined on the distal femur and proximal tibia. This provided necessary input to downstream processes. The variation in a populations' knees was captured by Statistical Shape Models (SSMs), and the subsequent use of a Graphical User Interface (GUI) was investigated to incorporate local constraints as part of sparse SSM estimation. These estimates formed the base of the implants' femoral components, and together with matching metal-backed, motion-guided tibial components were created using automated B-spline parametrisations. Sixteen unseen knees were used as test candidates and it was found that the resulting condyle estimations were sufficiently accurate, while the generated implant components matched normal knee anatomy. Both the GUI-based estimation and the automated design process showed good repeatability. The implant design presented here is ready for pre-clinical testing and evaluation.

AFRIKAANSE OPSOMMING: Pasiëntspesifieke Unikomaptementele Knie Vervangings (UKVs) kan moontlik 'n Osteoartritiese (OA) knie nader aan sy voorpatologiese toestand herstel as van-die-rak produkte. Nietemin, die huidige stand-van-die-kuns is steeds sterk afhanklik van die tegnikus se interpretasie en vaardigheid om gesonde geometrieë na te maak. Hierdie proefskrif het dus gefokus op die ontwikkeling van 'n betroubare, semi-automoatiese benadering tot implantaat ontwerp. Inter-pasiënt veranderlikheid en inter- en intra-waarnemer ooreenkoms en betroubaarheid is bestudeer vir 'n stel landmerke wat op die distale femur en proximale tibia gedefinieer is. Dit het die nodige insette vir afstroomprosesse verskaf. Die variasie in 'n populasie se knieë is gevang deur Statistiese Vormmodelle (SVs), en die daaropvolgende gebruik van 'n Grafiese Gebruikerskoppelvlak (GGK) is ondersoek om lokale beperkinge in te sluit as deel van 'n yl SV-skatting. Hierdie skattings het die basis van die implantate se femorale komponente gevorm, en is geskep met behulp van geoutomatiseerde B-spline parametrisasies tesaam met die ooreenstemmende metaalgesteunde, bewegingsgeleide tibiale komponente. Sestien versteekte knieë is as toetskandidate gebruik en daar is bevind dat die resulterende kondiele-skattings akkuraat genoeg was terwyl die gegenereerde implantaat-komponente ooreenstem met normale knie anatomie. Beide die GGK-gebaseerde skattings en die outomatiese ontwerpproses het goeie herhaalbaarheid getoon. Die implantaat ontwerp wat ons hier aanbied is gereed vir voor-kliniese toetsing en evaluering.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/103819
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