Knee evaluation observation

Taylor PC, Steuer A, Gruber J et al (2004) Comparison of ultrasonographic assessment of synovitis and joint vascularity with radiographic evaluation in a randomized, placebo-controlled study of infliximab therapy in early rheumatoid arthritis. Arthitis Rheum 50 1107-1116 Terslev L, Qvistgaard E, Torp-Pedersen S et al (2001) Ultrasound and power Doppler findings in jumper s knee preliminary observations. Eur J Ultrasound 13 183-189 Torreggiani WC, Al-Ismail K, Munk PL et al (2002) The imaging spectrum of Baker s (Popliteal) cysts. Clin Radiol 57 681-691... 

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. 

One of the most frequently used tests for fatigue-resistance evaluation is the well-known plotting of stress versus the number of cycles, usually referred to as the S-N (curve) relation . Various wave forms of cyclic stresses may be applied to a specimen to test its suitability to withstand prolonged strain. Machine elements are assessed to determine their practical endurance of industrial applications to which they may be exposed. Such tests focus on the nominal stress required to cause fatigue failure at some number of cycles. A logarithmic scale is almost always used for N, the number of cycles to failure. A schematic S-N plot is shown in Fig. 7.1. Note the horizontal line in plot (a), known as a knee , which represents the endurance limit . As implied by its name, at this level of stress, the specimen is characterized by its ability to endure a large number of stress-cycles at the stress level of the horizontal line and below it without failure. In plot (b), no such horizontal line is observed and the curve continues to decrease, indicating that the stress must be reduced for the test specimen to be able to withstand a certain number of cycles. 

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