Intra-articular pressure in rheumatoid arthritis of the knee. 3. Pressure changes during joint use.

Abstract

Royal Infirmary1Studies of pressure/volume relationships in control and diseased knees have demonstrated significant alterations in joint elastance (Jayson and Dixon, 1970). However, these studies were performed at rest and did not give information about changes in intra-articular pressure during joint use. One would never consider measurements in the stopped heart as adequate for study of its physiology, and similarly measurements in the resting joint present an incomplete picture. A further study was, therefore, conducted of the changes in intra-articular pressure occurring during both a standard series of exercises and walking. Subjects studiedMeasurements during formal knee exercises were performed on nine knees from eight control subjects and on sixteen knees from sixteen patients with definite or classical rheumatoid arthritis (Ropes, Bennett, Cobb, Jacox, and Jessar, 1959). They weie repeated on one control and one rheumatoid knee after intervals of 4 and 3 months. The repeated studies demonstrated that the results were reproducible but were not used for the statistical analysis. In nine rheumatoid knees, these investigations were performed immediately after initial joint aspiration, but in the others and in all the control knees they immediately followed measurement of the pressure/volume relationships described by Jayson and Dixon (1970).Measurements of pressures during walking were made in six control and four rheumatoid knees. Both knees from one control subject were used and showed similar results. In four of the control knees and in one rheumatoid knee measurements had also been made during formal exercises. MethodIn all studies the techniques for cannulating the joint, recording the intra articular pressure, and adding and withdrawing effusion, were as described by Jayson and Dixon (1970). Measurement of the pressures produced with each movement were made, when possible, with volumes of simulated effusion of 0, 20, 40, 60, 80, and 100 ml. On some occasions additional readings were taken at narrower intervals. Some subjects were unable to tolerate large volumes of simulated effusion and in others joint rupture occurred so that useful readings were obtained only at lower volumes.During the formal exercises four manoeuvres were performed in a regular sequence at each volume: elevation of the extended leg, isometric elevation, quadriceps setting, and passive knee flexion. In these and other studies this last movement appeared particularly likely to cause joint rupture and was therefore discontinued after nine experiments.Elevation of the leg The subject was encouraged to relax completely with the knee extended. He was then instructed to elevate the extended lovwer limb if possible so that the hip was flexed to 900, and to hold this position for 5 seconds before slowly lowering the leg back onto the couch and relaxing. With larger volumes of simulated effusion, some subjects developed increasing difficulty and were unable to maintain the knee in the fully extended position (00) during elevation. There w...

Reciprocal relationship of synovial fluid volume and Oxygen tension

“…Therefore, the rate limiting factor on the effective blood flow to the joint (that portion of the synovial circulation involved in the transport of solutes) is dependent on the volume of the joint effusion and the intraarticular pressure generated by it. Synovial effusions exceeding 50 ml in volume can lead to extraordinarily high pressures (14,15). In our patients with knee effusions exceeding 50 ml, the synovial fluid PO, values were invariably less than 50 mm Hg (Figure 2).…”

Factors determining the level and changes in intra‐articular pressure in the knee joint of the dog.

“…Changes in synovial fluid volume are reflected by changes in intra-articular hydrostatic pressure. It has been demonstrated in normal joints of humans and animals (Levick, 1979a;Jayson & Dixon, 1970c), that movement of the joint also causes changes in intra-articular pressure resulting in movement of fluid in and out of the joint, in addition to that which occurs as a result of the hydrostatic and osmotic pressure gradients in an immobilized joint (Levick, 1979b(Levick, , 1980. Intra-articular pressure and volume relationships in abnormal joints have also been investigated in man (Jayson & Dixon, 1970a, b, c) and animals (McCarty, Phelps & Pyenson, 1966), along with studies on joint effusions (Caughey & Bywaters, 1963;Eyring & Murray, 1964;Palmer & Myers, 1968), and capsular compliance (Myers & Palmer, 1972).…”

Pressure erosions: A pattern of bone resorption in rheumatoid arthritis

“…Involved joints in patients with rheumatoid arthritis have higher than normal resting intraarticular pressures, which are further increased with joint motion and joint effusion, resulting in strain on the articular surfaces, the synovia1 lining, and the joint restraints (5). In addition to stretclhing and weakening the capsule and ligamentous fibers., increased intraarticular pressure may cause synovial cyst formation.…”