Human joints

In the electronics industry. Pis find wide appHcations as a dielectric material for semiconductors due to thermal stabiHty (up to 400°C) and low dielectric constant. Pis are being considered for use in bearings, gears, seals, and prosthetic human joints. The intended part can be machined or molded from the PI, or a film of PI can be appHed to a metallic part. Because of their superior adhesion, dielectric integrity, processing compatibUity, and lack of biological system impact. Pis have been used in many biological appHcations with particular success as body implants. 

A few elements, among them fluorine and phosphoras, occur naturally with just one isotope, but most elements are isotopic mixtures. For example, element number 22 is titanium (Ti), a light and strong metal used in Jet engines and in artificial human Joints. There are five naturally occurring isotopes of Ti. Each one has 22 protons in its nuclei, but the number of neutrons varies from 24 to 28. In a chemical reaction, all isotopes of an element behave nearly identically. This means that the isotopic composition of an element remains essentially constant. The isotopic composition of Ti (number percentages) is... 

Merry, P., Grootveld, M., Lunec, J. and Blake, D.R (1991). Oxidative damage to lipids within the inflamed human joint provides evidence of radical-mediated hypoxic-reperfusion injury. Am. J. Clin. Nutr. 53, 362S-369S. 

AGAINST FREE-RADICAL DAMAGE IN THE Human joint... 

Hypoxic-reperfusion injury in the inflamed human joint. Lancet i, 289-293. 

When a human joint has been destroyed or damaged by disease or injury, surgical replacement, also addressed to as arthroplasty, is normally required. A total joint replacement includes components that simulate a natural human joint (16) ... 

Evans, C.H., Robbins, P.D., Ghivizzani, S.C., Herdon, J.H., Kang, R., Bahnson, A.B. et al. (1996) Clinical trial to assess the safety, feasibility, and efficacy of transferring a potentially anti-arthritic cytokine gene to human joints with rheumatoid arthritis. Hum. Gene Ther., 7, 1261-1280. 

Recently, we have provided evidence that hypoxic reperfusion injury occurs in the inflamed human joint [2,12,13]. Joint movement in patients with RA produces intra-articular pressures in excess of the synovial capillary perfusion pressure. This phenomenon does not occur in normal joints, where the pressure remains subatmospheric throughout a movement cycle. During exercise of the inflamed joint, the intra-articular pressure is transmitted directly to the synovial membrane vasculature, producing occlusion of the superficial synovial capillary bed and ischaemia. Reperfusion of the synovial membrane occurs when exercise is stopped. Recently, electron spin resonance spectroscopy with spin trapping was employed to demonstrate that synovial tissue from a patient with RA generated ROI following a transient hypoxic... 

After my return to Boston, I extended my work on hyaluronan from the vitreus and the rooster comb to the synovial fluid. The physical properties, such as viscosity and elasticity, of synovial fluid were poorly understood, especially in human joints. I started to investigate the physical properties of cattle synovial fluid. As I had done 20 years earlier in Budapest, I went to the slaughterhouses of the Boston area and collected joint fluids. This time I was interested in how aging affects the physical properties and hyaluronan content of the joint fluid. The physical properties or, in more scientific terms, the rheology of the fluid is important because its role is to protect and lubricate the tissues of the joint. I traveled to Iowa to collect synovial fluids from cattle herds fed various diets that contained hormones. I hoped to discover a hormonal control of hyaluronan synthesis, similar to the one Szirmai and I had found that controlled hyaluronan synthesis in the rooster comb. 

Human joint (synovial) fluid 1400-3600 The volume of the synovial fluid increases under inflammatory conditions. This leads to a decreased HA concentration. 

Dowson D, Unsworth A, Wright V (1970) Analysis of Booted lubrication in human joints. J Meeh Eng Sci 12 364-369... 

Dowson, D, Modes of Lubrication in Human Joints, Proc. Inst. Mech. Engrs., 1966, 181, 3J, 45. 

W30. Wood, D. D., Ihrie, E. J., Dinarello, C. A., and Cohen, P. L. Isolation of an interleukin-1-like factor from human joint effusions. Arthritis Rheum. 26, 975-983 (1983). 

Bayliss MT, Davidson C, Woodhouse SM, Osborne DJ. Chondroitin sulpha-tion in human joint tissues varies with age, zone and topography. Acta Orthop Scand Suppl 1995 266 22-25. 

Xu, Y. and HoUerbach, J.M., Identification of human joint mechanical properties from single trial data, IEEE Trans. Biomed. Eng. BME-45 1051-1060,1998. 

FIGURE 49.1 Three types of articulating surface motion in human joints. 

Woltring H.J., Huiskes R., deLange A., and Veldpaus F.E. 1985. Finite centroid and helical axis estimation from noisy landmark measurements in the study of human joint kinematics. ]. Biomech. 18 379. 

R. Huiskes, Some fundamental aspects of human joint replacement. Analyses of stresses and heat conduction in bone-prosthesis structures, Acta Orthop. Scand. Suppl. 185 (1980) 1-208. 

Grabowski PS, Macpherson H, Ralston SH. Nitric oxide production in cells derived from the human joint. Br J Rheumatol 1996 35 207-12. 

Deamley PA. 1999. A review of metallic, ceramic and surface-treated metals used for bearing surfaces in human joint replacements. Proc Inst Mech Eng [H] 213 107-135. 

Examples of knee arthroplasty during the 1960s. (A) Walldius hinged knee replacement (B) the Shiers, Walldius, and Guepar hinged knee replacements, superimposed over the anatomy of the knee (reprinted with permission from Walker RS. 1977. Human joints and their artificial replacements. Springfield, IL CC Thomas Publisher) (C) Macintosh tibial plateau and (D) McKeever tibial plateau. 

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