The measurement of stiffness in human joints

Abstract

Goddard, Dowson, Longfield and Wright, The measurement o/sti~ness in human joints 229 ConclusionsThe small scale capillary viscometer has proved to be a versatile and convenient instrument to use for the determination of the flow curves of small quantities of polymer melts. The piston speed can be rapidly and accurately set over a speed range of I000:1. The melt pressure is measued directly above the capillary, which has the advantage over measuring the pressure in the piston face, or the thrust on the piston, m that the frictional forces in the piston, and the pressure drop in a long barrel do not have to be allowed for. Rapid pressure changes such as those that oeeur in oscillatory flow, can be detected (the transducer response time is 3 #s). Temperature control of the melt is within 0.5 deg. C., and temperature changes can be rapid because of the low thermal capacity of the barrel, The total cost of the instrument was about s 1,500. ~u,mTa~a~'yA small scale capillary viscometer that is capable of measuring the flow curves of 2 3 gins of molten polymer over the shear rate range 0.4 sec 1 to 20,000 see -I is described. A piezo electric crystal pressure transducer is used to measure the pressure directly above the capillary. Flow curves are given for anionic polystyrenes and polyethylene fractions, and it is shown that the viscosities measured agree with determinations in a cone and plate viscometer. Zusammen/assungEs wird ein maBstgblich kleines Kapillarviskosimeter ffir 2-3 g gesehmolzener Polymere besehrieben, das die DurchfluBkurve in Abhhmgigkeit vom Scherkoeffizienten im Bereich yon 0,4 sec -~ bis 20000 sec -x bestimmt. Verwendet wird ein piezoelektrischer KristallDruckaufnehmer, der den Druek genau fiber der Kapillare miBt. Angeffihrt werden DurchfluBkurven ffir anionische Polystyrole und Poly~thylenanteile. Es wird gezeigt, dab die gemessenen Zs mit denen yon Kegel-und Plattendichtemessern fihereinstimmen. Re/erences

Measurement of Outcome in Rheumatic Diseases

“…Goddard et al (1969), in our Unit, employed a sinosoidal motion to investigate the knee, and measured the resistive torque, plotting it in relation to angular displacement. To overcome inertial effects, Thompson et al (1978) produced an alternative knee arthograph in which the patient's knee was flexed horizontally with the patient lying on his side.…”

A robot‐assisted study of intrinsic muscle regulation on proximal interphalangeal joint stiffness by varying metacarpophalangeal joint position

“…The hysteresis was likely due to the plastic properties of the joint, with viscous effects negligible at low joint speed. 11,28 Future studies can be designed to study the viscoelastic properties of finger joints, for example, by collecting and analyzing torque-angle data over a wide range of joint speeds. The robot system developed in this study could be conveniently configured to perform such well-controlled experimental studies.…”

“…Electromyographic and anesthesia studies have shown that that finger joint movement with a low passive speed did not produce muscle contraction. 11,17,31,32 In addition, any voluntary muscle contraction was easily detectable with the continuous monitoring of the torque-angle data on the computer screen, because slight muscle activity would cause a large deviation from the highly reproducible passive torque-angle loops (Fig. 4).…”

“…In a passive state, joint stiffness is an integration of elasticity, plasticity, and viscosity, which may be best characterized by the torque-angle relationship. 11,23,25,30 Previous studies have shown that the elastic component is a major contributor to the stiffness of human MCP joint 11,13 and cat wrist joint. 28 The effects of inertia, friction, and viscosity on finger joint stiffness were found to be <10% in normal hands.…”

“…Attempts have been made to develop quantitative methods to study finger joint stiffness of normal hands 8,9 and hands affected by arthritis, 10-12 edema, 13 burns, 14 aging, 11,15 -17 gender, 11 temperature, 11,13 and therapy. 18 Ingpen and Kendall 16 constructed a device to indirectly quantify the stiffness of the MCP joint by timing the free fall of a standard lever extended from the MCP joint through an arc of 10 degrees.…”