The use of a force-controlled dynamic knee simulator to quantify the mechanical performance of total knee replacement designs during functional activity

DesJardins, John D.; Walker, Peter S.; Haider, Hani; Perry, Jacquelin

doi:10.1016/s0021-9290(00)00094-4

Cited by 109 publications

(93 citation statements)

References 54 publications

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“…Similarly, variability in loading and kinematics 9 and in resulting wear rates 10,11 is commonly observed in simulator testing. Force controlled wear simulators 9,12 aim to reproduce knee joint loading to evaluate kinematics and wear of implant designs.…”

Section: Introductionmentioning

confidence: 92%

“…9,12 The semi-constrained geometry had a single sagittal radius, while the unconstrained implant was flat centrally with a posterior lip. The meshes and boundary conditions of the FE model (Fig.…”

Section: Finite Element Modelmentioning

confidence: 99%

“…Variability in the loading profiles was quantified from published data 9 by determining a range for each of the loading profiles at 100 temporal locations throughout the gait cycle. While the variability was presented for 6 different designs, the same loading condition was desired for each implant and it was therefore assumed that a similar level of variability could be applied to a single implant design.…”

Section: Probabilistic Modelmentioning

confidence: 99%

“…This technique accounted for the different variability levels observed throughout the gait cycle in the AP force and IE torque. 9 The translational and rotational alignment parameters represented variability in component alignment in the experiment (Fig. 1, Table 1).…”

Section: Probabilistic Modelmentioning

confidence: 99%

“…Force controlled wear simulators 9,12 aim to reproduce knee joint loading to evaluate kinematics and wear of implant designs. Component wear is related to interface contact pressures and relative motions, [13][14][15] and changes in kinematics have been directly related to wear rate in in vitro studies.…”

Section: Introductionmentioning

confidence: 99%

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Effects of knee simulator loading and alignment variability on predicted implant mechanics: A probabilistic study

et al. 2006

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Inherent variability in total knee arthroplasty loading and alignment, present in vivo and in simulator testing, may ultimately influence polyethylene tibial insert wear and long-term performance. The effect of this variability was quantified on implant kinematics and contact mechanics during simulated gait loading conditions using semi-constrained and unconstrained fixed bearing, cruciate retaining implants. A probabilistic finite element model of the Stanmore knee wear simulator was utilized to estimate the envelope of anterior-posterior (AP) and internal-external (IE) position and contact pressure and to evaluate the variability in corresponding ranges of motion (ROM). Variability levels were represented by standard deviations of up to 10% of the maximum value for load inputs and 0.25 mm and 0.58 for component alignment inputs. Model predictions compared well with experimental simulator results for the semi-constrained implant, with predicted positional envelopes of up to 1.8 mm (AP) an 3.48 (IE) for the semi-constrained and upto 2.6 mm (AP) and 3.78 (IE) for the unconstrained implant at the variability levels evaluated. ROM varied by up to 22%, while peak contact pressure variations averaged less than 2 MPa for both designs. For each implant, loading variability was more influential during the swing phase of gait, while alignment variability affected kinematics more during stance. The relative rank of sensitivities showed differences between the two designs, providing insight into critical parameters affecting kinematics and contact characteristics. ß

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Section: Introductionmentioning

confidence: 92%

Section: Finite Element Modelmentioning

confidence: 99%

Section: Probabilistic Modelmentioning

confidence: 99%

Section: Probabilistic Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of knee simulator loading and alignment variability on predicted implant mechanics: A probabilistic study

et al. 2006

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The effect of contact area on wear in relation to fixed bearing and mobile bearing knee replacements

Sathasivam

Walker

Campbell

et al. 2001

J. Biomed. Mater. Res.

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It is generally assumed that the wear rates in knee replacements are reduced as the contact area is increased. Hence, fixed bearing or mobile bearing designs with large contact areas throughout the full range of flexion wear less than partially conforming fixed-bearing designs. This hypothesis was investigated in an experimental model, where flat-ended ultra high molecular weight polyethylene pins of varying diameters were reciprocated and rotated on polished metal plates under a constant load with serum lubrication. The pin diameters ranged from 8-23 mm, giving nominal contact pressures from 23.9-2.8 MPa, covering the range associated with a wide spectrum of total knees including mobile-bearings. For pin diameters of 8-12 mm, the mean wear rates were in the range of 5.0-16.0 E-10 g/cycle. For diameters of 17 and 23 mm, the mean wear rates were approximately 1.0 E-10 g/cycle. The latter wear rates were significantly less than the former. Scanning electron microscopy indicated milder wear processes with the larger diameters, while the smaller diameters exhibited transverse ripples and cracks and detachment of thin layers from the surface. The percentages of granules (mostly submicron), fibrils and flakes, and the sizes of these particle types were similar among all pin diameters, except that, for the 23 mm pin diameter, the percentage of fibrils increased and of flakes decreased. This work supports the hypothesis that larger contact areas, up to the maximum area tested in our study, produce lower wear rates, and suggests that there is no disadvantage regarding particle type or size associated with the larger areas of contact.

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Effects of in vitro wear of machined and molded UHMWPE tibial inserts on TKR kinematics

Benson

DesJardins

LaBerge

2001

J. Biomed. Mater. Res.

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The effect of manufacturing process on the wear and mechanical performance of a total knee replacement (TKR) design was investigated with the use of a force-controlled knee joint simulator. Ultra-high molecular weight polyethylene (UHMWPE) tibial inserts processed by direct compression molding from 1900H resin were compared to UHMWPE tibial inserts machined from a compression-molded sheet of GUR 1050. Both sets of components had the same posterior-cruciate-retaining geometry, and were identically aligned with cobalt-chromium-molybdenum alloy femoral components. Wear tests were conducted at a frequency of 1 Hz for 4 million cycles with the use of a standard walking cycle pattern. Implant kinematics, including anterior-posterior (AP) displacement and internal-external (IE) rotation in response to applied loads were monitored. Gravimetric wear, surface roughness, and surface morphology were used to characterize the wear process of the UHMWPE inserts. Results showed that the molded UHMWPE inserts exhibited less gravimetric wear over time than the machined inserts of the same design. Both the machined and molded components exhibited scratching, pitting, and burnishing over their wear areas. The AP displacement distance per cycle of the molded tibial inserts decreased over the course of testing, resulting in a shorter total testing displacement for this group compared to machined tibial inserts. Although AP displacement distance per cycle for machined tibial inserts did not change significantly over the course of testing, their position relative to the femoral components shifted posteriorly over time, resulting in an elongated wear track.

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The use of a force-controlled dynamic knee simulator to quantify the mechanical performance of total knee replacement designs during functional activity

Cited by 109 publications

References 54 publications

Effects of knee simulator loading and alignment variability on predicted implant mechanics: A probabilistic study

Effects of knee simulator loading and alignment variability on predicted implant mechanics: A probabilistic study

The effect of contact area on wear in relation to fixed bearing and mobile bearing knee replacements

Effects of in vitro wear of machined and molded UHMWPE tibial inserts on TKR kinematics

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