AN EXAMINATION OF CYRIAX PASSIVE MOTION TESTS WITH PATIENTS HAVING OSTEOARTHRITIS OF THE KNEE

Background and Purpose. We explored the construct validity and test-re test reliability of the passive motion component of the Cyriax soft ti ssue diagnosis system. We compared the hypothesized and actual pattern s of restriction, end-feel, and pain/resistance sequence (P/RS) of 79 subjects with osteoarthritis (OA) of the knee and examined association s among these indicators of dysfunction and related constructs of join t motion, pain intensity, and chronicity. Subjects. Subjects had a mea n age of 68.5 years (SD=13.3, range=28-95), knee stiffness for an aver age of 83.6 months (SD=122.4, range=1-612), knee pain averaging 5.6 cm (SD=3.1, range=0-10) on a 10-cm visual analogue scale, and at least a 10-degree limitation in passive range of motion (ROM) of the knee. Me thods. Passive ROM (goniometry, n=79), end-feel (n=79), and P/RS durin g end-feel testing (n=62) were assessed for extension and flexion on t hree occasions by one of four experienced physical therapists. Test-re test reliability was estimated for the 2-month period between the last two occasions. Results. Consistent with hypotheses based on Cyriax's assertions about patients with OA, most subjects had capsular end-feel s for extension; subjects with tissue approximation end-feels for flex ion had more flexion ROM than did subjects with capsular end-feels, an d the P/RS was significantly correlated with pain intensity (rho=.35, extension; rho=.30, flexion). Contrary to hypotheses based on Cyriax's assertions, most subjects had noncapsular patterns, tissue approximat ion end-feels for flexion, and what Cyriax called pain synchronous wit h resistance for both motions. Pain intensity did not differ depending on end-feel. The P/RS was not correlated with chronicity (rho=.30, ex tension; rho=-.01, flexion). Reliability, as analyzed by intraclass co rrelation coefficients (ICC[3,1]) and Cohen's kappa coefficients, was acceptable (greater-than-or-equal-to.80) or nearly acceptable for ROM (ICC=.71-.86, extension; ICC=.95-.99, flexion) but not for end-feel (k appa=.17, extension; kappa=.48, flexion) and P/RS (kappa=.36, extensio n; kappa=.34, flexion). Conclusion and Discussion. The use of a quanti tative definition of the capsular pattern, end-feels, and P/RS as indi cators of knee OA should be reexamined. The validity of the P/RS as re presenting chronicity and the reliability of end-feel and the P/RS are questionable. More study of the soft tissue diagnosis system is indic ated. [Hayes KW, Petersen C, Falconer J. An examination of Cyriax's pa ssive motion tests with patients having osteoarthritis of the knee. Ph ys Ther. 1994; 74:697-709.]