Knee wear simulators

Burgess IC, Kolar M, Cunningham JL, Unsworth A (1997), Development of a six station knee wear simulator and preliminary wear results , Proc Inst Mech Eng H, 211, 37-47. 

Ezzet KA, Hermida JC, Colwell Jr. CW, D Lima DD. Oxidized zirconium femoral components reduce polyethylene wear in a knee wear simulator. Clin Orthop Relat Res 2004 November(428) 120-4. 

Both the Leeds and the New Jersey knee machines must have been pioneers of their time in wear simulators because, even as late as 1992, knee wear simulator designs were being published, which provided for only axial force varying with flexion [46]. Such simulators had IE free to rotate, and ML and VV were locked but adjustable during setup for alignment. AP displacement was coupled mechanically with flexion to provide partial constraint of the centroid path [46]. 

FIGURE 26.5 Hydraulic six-station displacement-control Knee Wear Simulator by AMTI, Watertown, Massachusetts, USA. 

Contemporary Knee Wear Simulators and the Much-Debated Force- versus Displacement-Control Paradigms... 

FIGURE 26.16 Six-station displacement-controlled Knee Wear Simulator by ProSim, United Kingdom. This machine has force-control capability for AP and IE torque but no soft tissue simulation. 

Laz P, Pal S, Halloran J, Petrella J, Rullkoetter PJ. Probabilistic finite element prediction of knee wear simulator mechanics. J Biomech 2006 39(12) 2303-10. 

A knee joint simulator designed to evaluate the mechanical and tribological characteristics of total replacement knee joints will be described. Measurements of penetrations of metallic femoral components into the polymeric tibial components by means of dual index holographic contouring will be presented and the findings compared with observations from detailed studies of wear in well-controlled laboratory machines and the limited evidence of in-vivo performance of replacement knee joints. 

A knee joint simulator was designed and built in the bioengineering laboratory at Leeds in the late 1970 s to enable the mechanical and tribological characteristics of current and projected knee joint replacements tp.he assessed. The simulator has been described by Dowson et al and it is shown in Figure 1. Realistic load and motion cycles are applied to the knee joints to simulate any desired activity, but usually walking, and the penetration of the metallic femoral components into the polymeric tibial components after a large number of cycles can then be used to assess the life of the joints. Furthermore, the penetrations recorded, which include both wear and creep, can be related to results of laboratory wear studies of the behaviour of UHMWPE and to the in-vivo performance of total replacement knee joints. The simulator is therefore an Important machine in both the pragmatic and fundamental aspects of total replacement knee join development. 

Representation of Wear Scar in Leeds Knee Joint. (Simulator Test). 

Ash HE, Burgess IC, Unsworth A (2000), Long-term results for Kinemax and Kinematic knee bearings on a six-station wear simulator , Proc Inst Mech Eng, 214, 437 47. 

Flannery M, McGloughlin T, Jones E, Birkinshaw C (2008), Analysis of wear and friction of total knee replacements. Part I. Wear assessment on a three station wear simulator , Wear, 265, 999-1008, DOI 10.1016/j.wear.2008.02.024. 

Scholes SC, Unsworth A, Jones E (2007), Polyurethane unicondylar knee prostheses simulator wear tests and lubrication studies , Phys Med Biol, 52, 197—212, DOl 10.1088/0031-9155/52/1/013. 

White SE, Whiteside LA, McCarthy DS, Anthony M, Poggie RA. Simulated knee wear with cobalt chromium and oxidized zirconium knee femoral components. CUn Orthop Relat Res 1994 December (309) 176-84. 

Affatato S, Leardini A, Leardini W, Giannini S, Viceconti M. Meniscal wear at a three-component total anMe prosthesis by a knee joint simulator. J Biomech 2007 40(8) 1871-6. 

Tipper J, Galvin A, Williams S, McEwen H, Stone M, Ingham E, et al. Isolation and characterization of UHMWPE wear particles down to ten nanometers in size from in vitro hip and knee joint simulators. J Biomed Mater Res 2006 78A 473-80. 

Dowson D, Gillis BJ, Atkinson JR. Penetration of metallic femoral components into polymeric tibial components observed in a knee joint simulator. American Chemical Society Symposium Series No. 287, Polymer Wear Contr 1985 p. 215-28. 

Haider H, Sekundiak TD, Garvin KL. Simulation of the spring-based soft tissue restraint in testing knee wear under force control. Proceedings of the First International Conference on Mechanics of Biomaterials Tissues. Hawaii, USA 2005 December. 

Fisher J, McEwen HMJ, Tipper JL, Jennings LM, Farrar R, Stone MH, Ingham E. Wear-simulation analysis of rotating-platform mobile bearing knees. Orthop 2006 29 36-41. 

Experiments were carried out in the simulator on an early form of Freeman-Swanson Knee Joint and on a Leeds Knee Joint. Distilled water was allowed to drip onto the prosthesis to wet the interface, the flow rate being adjusted to maintain temperature of the tlbial component at 37 C. Contour diagrams based upon holography are recorded for the initial and worn tlbial components of each joint in Figures 3 and 4 and schematic representations of the wear scars are shown in Figures 5 and 6. 

The derived wear factor (k) for the Freeman-Swansog and Leeds knee joints tested in the simulator for about 10 cycles are both interesting and similar. The ln-vlvo Freeman-Swanson joint was kindly made available by Professor S.A.V. Swanson and the conditions of service were not known with any certainty. The joint had functioned in an elderly patient for some four years, with a light to medium level of walking activity. It was therefore assumed that /PdX remained constant at 47.7 Nm/cycle and that the patient achieved 6000 strides or 3000 loading cycles per day. These assumptions are consistent with a subsequent study of the walking activity of patients fitted with total replacement joints reported by Wallbrldge and Dowson, but considerable scope for errors... 

In the case of human hip and knee prostheses, some data is available (9) which compares wear test results from joint simulators, and other laboratory tests with "in-vivo" wear rates. In joint simulators the amplitude and frequency of motion and the cyclic loads related to walking are simulated as closely as possible. The... 

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