Biomechanik von unikondylären und bikondylären Knieendoprothesen bei alltagsrelevanten Lokomotionsformen

Publication: Book/ReportDissertations

Abstract

Knee arthroplasty is a successful and effective treatment for patients with degenerative end-stage knee osteoarthritis. The primarily aim of knee replacement is to relief pain and restore joint function. Generally, there is a distinction between unicondylar and bicondylar knee arthroplasty. In unicondylar knee arthroplasty only the joint compartment affected by osteoarthritis is replaced. Both cruciate and collateral ligaments are retained. Conversely, in bicondylar knee arthroplasty both the medial and lateral compartments of the tibia and femur are replaced. The anterior cruciate ligament is usually resected, whereas there are posterior cruciate ligament-retaining or substituting prosthetic designs. To date, unicondylar knee arthroplasty still represents a relatively small proportion of all knee arthroplasty surgeries. However, it is often hypothesised that unicondylar knee arthroplasty restores n o r m a l knee joint kinematics, in contrast to bicondylar or total knee arthroplasty respectively. This potential benefit of unicondylar knee arthroplasty has not been investigated under the consideration of activities of daily living. The aim of the current dissertation was a biomechanical examination of patients after a unilateral knee arthroplasty surgery compared to a healthy control group with regard to potential differences in terms of selected parameters during activities of daily living. There was a special focus on kinematics and kinetics in subjects with unicondylar knee arthroplasty compared to subjects with bicondylar knee arthroplasty.Gait analysis was performed by means of a 3D, 10-camera motion analysis system (VICON MX40, Vicon Motion Systems Ltd, Oxford, UK). Simultaneously, ground reaction forces were collected using force plates (Kistler Instrumente AG, Winterthur, CH). Electromyo-graphic raw signals were recorded at 1500 Hz from 8-channel telemetric electromyographic system (TeleMyo, Noraxon USA Inc., Scottdale, USA). The AnybodyTM Modeling System(AnyBody Technology, Aalborg, DK) was used to perform lower-limb inverse dynamics according to the anatomical landmark scaled model. The subjects performed level walking, stair climbing and negotiated a ramp.Patients with bicondylar arthroplasty exhibited considerable impaired knee internal rotation in their replaced knee joint particularly during decline walking and stair climbing compared to the control group. Patients with unicondylar knee arthroplasty revealed impaired knee internal rotation only in comparison to their non-affected knee. No difference was found between subjects with unicondylar and bicondylar knee arthroplasty, regardless of the locomotion task.In the first place, congruency between the femoral component and tibial inlay serves as an explanation for the restricted tibial rotation around the longitudinal axis of the knee joint in subjects after total knee arthroplasty. Due to the congruency, rotational resistance is induced between the two joint components that constraints tibial transverse plane motion. Additionally, high friction between the artificial joint components and simultaneously relatively low internal rotation moment magnitudes during stair climbing and decline walking may exert a mechanical resistance that reduces axial rotation in both knee arthroplasty designs. Apart from the implant shape, high friction enhances torsional shear, acting on the bone-implant interface. This mechanism may lead to migration around the longitudinal axis and potentially to loosening of the tibial component. Co-contraction between the medial and lateral hamstrings, as an explanatory approach, appears not to restrict knee internal rotation in patients after knee arthroplasty surgery. Based on the results of the current dissertation, clear advantages of unicondylar knee arthroplasty compared to bicondylar or total knee arthroplasty in terms of normal joint kinematics and kinetics can not be confirmed.
Original languageGerman
Place of PublicationKöln
PublisherDeutsche Sporthochschule Köln
Number of pages145
Publication statusPublished - 2018

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