No abstract

(1976). Annals of the Rheumatic Diseases, 35, 56-59. Lubrication of synovial membrane. (1) An apparatus has been constructed to measure the coefficient of friction of synovial membrane against a glass slider. (2) Provision was made to vary the load on the specimens. (3) The coefficient offriction varied from 0-006 to 0 07. (4) A presentation similar to that used in the Sommerfeld analysis of journal bearings indicated that in these experiments synovial membrane was lubricated in the hydrodynamic regimen.The stiffness of normal joints measured in the midrange of motion appears to be due to various tissuesskin 2 %, tendons 10%, muscle 41 %, and capsule 47% (Wright, Longfield, and Dowson, 1969). Similarly, the increased stiffness of joints with osteoarthrosis seems to be due mainly to changes in the capsule (Goddard and others, 1969). Some of these tissues ride over the joint on the synovial membrane and consequently lubrication of the membrane is important when considering joint function.The only available data on the lubrication of the synovial membrane are those of Radin and others (1971), who loaded specimens of bovine synovial membrane against a moving glass slider. The coefficient of friction between the membrane and glass was independent of the speed of movement and viscosity of the lubricant. From these results the authors concluded that the synovial membrane was operating in the boundary lubrication regimenthe boundary lubricant being the hyaluronic acid present in the synovial fluid. However, the variation of friction with load was not investigated and the non-newtonian properties of synovial fluid were not taken into account.To study this problem further a special softtissue friction testing machine was designed and constructed, and the results from this apparatus are presented in this paper.Materials and methods Specimens of synovial membrane were dissected from human cadaveric knees. From the geometry of the knee joint it is apparent that different sections of the membrane will operate under different conditions. Calculations based on the data of Smith (1972) and Morrison (1967) showed a speed range for the synovial membrane between 0 and 450 mm/s during a normal walking cycle (Cooke, 1974). On the basis of these data, apparatus ( Fig. 1) was designed with a range of operation similar to that under normal physiological conditions. Specimens of synovial membrane were loaded against the moving glass slider (Fig. 2) in the presence of bovine synovial fluid. The early experiments indicated that the variation of frictional force with time was insignificant. The majority of experiments, therefore, were conducted with specimens under load for a short period, normally 1 minute; then the load was released for approximately 10 seconds, during which time the load was changed and the specimens were reloaded against the sliding surface. The frictional torque was measured during the motion of the slider.Theoretical considerations A general guide to the mode of lubrication, which is frequently used in engineering ...

No abstract

No abstract

No abstract