Reliability, validity, and responsiveness of four knee outcome scales for athletic patients

Background: Many patient-based knee-rating scales are available for the eva luation of athletic patients. However, there is little information on the m easurement properties of these instruments and therefore no evidence to sup port the use of one questionnaire rather than another. The goal of the pres ent study was to determine the reliability, validity, and responsiveness of four knee-rating scales commonly used for the evaluation of athletic patie nts: the Lysholm scale, the subjective components of the Cincinnati knee-ra ting system, the American Academy of Orthopaedic Surgeons sports knee-ratin g scale, and the Activities of Daily Living scale of the Knee Outcome Surve y. Methods: All patients in the study had a disorder of the knee and were acti ve in sports (a Tegner score of greater than or equal to4 points). Forty-on e patients who had a knee disorder that had stabilized and who were not rec eiving treatment were administered all four questionnaires at baseline and again at a mean of 5.2 days (range, two to fourteen days) later to test rel iability. Forty-two patients were administered the scales at baseline and a t a minimum of three months after treatment to test responsiveness. The res ponses of 133 patients at baseline were studied to test construct validity. Results: The reliability was high for all scales, with the intraclass corre lation coefficient ranging from 0.88 to 0.95. As for construct validity, th e correlations among the knee scales ranged from 0.70 to 0.85 and those bet ween the knee scales and the physical component scale of the Short Form-36 (SF-36) and the patient and clinician severity ratings ranged from 0.59 to 0.77. Responsiveness, measured with the standardized response mean, ranged from 0.8 for the Cincinnati knee-rating system to 1.1 for the Activities of Daily Living scale. Conclusions: All four scales satisfied our criteria for reliability, validi ty, and responsiveness, and all are acceptable for use in clinical research .