Total knee replacement wear simulators

Knight LA, Pal S, Coleman JC, Bronson F, Haider H, Levine DL, Taylor M, Rullkoetter PJ. Comparison of long-term numerical and experimental total knee replacement wear during simulated gait loading. J Biomech 2007 40(7) 1550-8. 

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. 

Utzschneider S, Harrasser N, Schroeder C, Mazoochian F, Jansson V (2009), Wear of contemporary total knee replacements - a knee simulator study of six current designs , Clin Biomech, 24, 583-588, DOI 10.1016/j.clinbiomech.2009.04.007. 

Blunn GW, Bell CJ, Walker PS, Chaterjee S, Perry J, Cambell P, Haider H, Paul JP. Simulator testing of total knee replacements, chapter 9. In Hutchings IM, editor. Friction, lubrication and wear of artificial joints. Professional Engineering Publishing 2003. p. 113-25. ISBN 1 86058 363 6. 

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. 

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. 

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... 

---