SUNConferences, 17th Annual Conference of the Rapid Product Development Association of South Africa

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Patient specific knee joint - where are we today?
Kyung Jin Cho, Pieter Erasmus, Jacobus Muller

Last modified: 2016-10-04

Abstract


The knee is the largest and most complex joint in human body consisting of three independent compartments with a wide individual variation in surface geometry. Damage to the joint surface can occur in a single, in two or in all three compartments. When there is severe damage the best solution is to resurface the damaged compartments to have metal on polyethylene contact instead of bone on bone contact. Prosthesis design and fit play a major role on the functional outcomes of the replacement as it has to fit in the individual soft tissue sleeve of the patient, consisting of the joint capsule and the knee ligaments. Considering the wide individual difference in the morphology of the joint it is technically not possible to do it perfectly with an “off the shelve” prosthesis. The best way to solve this problem is to develop and use patient specific prostheses as well as patient specific instruments. The patient specific instruments are designed on a 3D reconstruction of the limb based on the patient’s CT or MR scans and are typically 3D printed in Nylon. The prosthesis is designed in a similar way and can be manufactured by additive manufacturing using chrome – cobalt alloys and polyethylene. The patient specific instrumentation is already an economically viable option while prosthetic manufacturing, although possible, is at present too expensive for general use. We will discuss the basic biomechanics of the knee, the principles and current technologies for patient specific instrumentation and knee prostheses.