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Item type:Publication, Access status: with files , Influence of flexural rigidity on micromotion at the head-stem taper interface of modular hip prostheses(2019-06); ; ; Fretting corrosion as one reason for failure of modular hip prostheses has been associated with micromotion at the head taper junction. Historically the taper diameter was reduced to improve the range of motion of the hip joint. In combination with other developments, this was accompanied by increased observations of taper fretting, possibly due to the reduced flexural rigidity of smaller tapers. The aim of the study was to investigate how the flexural rigidity of tapers influences the amount of micromotion at the head taper junction. Three different stem and two different taper designs were manufactured. Experimental testing was performed using three different activity levels with peak loads representing walking, stair climbing and stumbling. The relative motion at the head-stem taper was measured in six degrees of freedom. Micromotion was obtained by subtraction of the elastic deformation derived from monoblock and finite element analysis. Less rigid tapers lead to increased micromotion between the head and stem, enlarging the risk of fretting corrosion. The influence of the stem design on micromotion is secondary to taper design. Manufacturers should consider stiffer taper designs to reduce micromotion within the head taper junction.Publicationtype: Journal ArticleScopus© Citations 20 325 685 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Analysis of surface-to-surface distance mapping during three-dimensional motion at the ankle and subtalar joints(2018-07-25); ; ; ; Joint surface interaction and ligament constraints determine the kinematic characteristics of the ankle and subtalar joints. Joint surface interaction is characterized by joint contact mechanics and by relative joint surface position potentially characterized by distance mapping. While ankle contact mechanics was investigated, limited information is available on joint distance mapping and its changes during motion. The purpose of this study was to use image-based distance mapping to quantify this interaction at the ankle and subtalar joints during tri-planar rotations of the ankle complex. Five cadaveric legs were scanned using Computed Tomography and the images were processed to produce 3D bone models of the tibia, fibula, talus and calcaneus. Each leg was tested on a special linkage through which the ankle complex was loaded in dorsiflexion/plantarflexion, inversion/eversion, and internal/external rotation and the resulting bone movements were recorded. Fiduciary bone markers data and 3D bone models were combined to generate color-coded distance maps for the ankle and subtalar joints. The results were processed focusing on the changes in surface-to-surface distance maps between the extremes of the range of motion and neutral. The results provided detailed insight into the three-dimensional highly coupled nature of these joints showing significant and unique changes in distance mapping from neutral to extremes of the range of motion. The non-invasive nature of the image-based distance mapping technique could result, after proper modifications, in an effective diagnostic and clinical evaluation technique for application such as ligament injuries and quantifying the effect of arthrodesis or total ankle replacement surgery.Publicationtype: Journal Article124