Reliability of a criterion-based test of athletes with knee injuries; where the physiotherapist and the patient independently and simultaneously assess the patient’s performance

A new criterion-based evaluation test method, has been developed in order to assess the functional ability of athletes with knee injuries, ‘Tests for Athletes with Knee-injuries’ (TAK). The physiotherapist and the patient assess independently and simultaneously the patient’s performance. The TAK comprises eight demanding functional activities with emphasis on strength, stability, springiness and endurance. Objectives: To evaluate the inter-rater and intra-rater reliability of TAK between the physiotherapist’s and the patient’s assessments. Further, to evaluate the relation between the functional tests in TAK and the isokinetic quadriceps muscle strength. Materials and methods: Fifty-nine subjects were included in the study. Thirty-one were anterior cruciate ligament (ACL) reconstructed, fourteen were ACL-injured not reconstructed and fourteen were healthy athletes. The inter-rater-reliability was evaluated by assessments of 59 subjects carried out by two independent physiotherapists using visual observation. The assessment was rated on a 0–10-point scale according to five elaborate criteria drawn up for each test. Simultaneously, the subjects were asked to rate their own performance on each test using a 0–10-point scale. The intra-rater-reliability of TAK was evaluated by a test–retest of 31 patients. The relation between the physiotherapist’s and the patients’ ratings as well as of the patients’ ratings at two different occasions were evaluated. Isokinetic quadriceps muscle strength was measured in a Biodex dynamometer on all 59 subjects in order to study the relation between quadriceps muscle strength and the results of the functional tests in TAK. Results: Inter-rater-reliability showed good consistency between the assessments of the two physiotherapists in seven of eight tests (κ = 0.62–0.78). The intra-rater-reliability was moderate to good (κ = 0.43–0.65) in the test–retest study. The consistency of the physiotherapist and the patients’ assessments differed, but showed good correlation. The consistency of the test–retest study of the patients’ assessment was low. The correlation between the isokinetic quadriceps muscle strength measured in a Biodex dynamometer and the results of the functional tests was moderate in this study. Conclusions: This criterion-based test method for athletes with knee injuries showed good inter-rater reliability and acceptable intra-rater reliability for the physiotherapists’ assessment. The consistency of the patients’ ratings was low. The correlation between isokinetic quadriceps muscle strength and functional tests in TAK was moderate. The validity has not been evaluated in this study but will be done in the future.