Background: A torn meniscus is one of the most common indications for knee surgery. The purpose of this study was to determine the psychometric properties of the Lysholm knee score and the Tegner activity scale when used for patients with a meniscal injury of the knee.

Methods: Test-retest reliability, content validity, criterion validity, construct validity, and responsiveness to change were determined for the Lysholm score and the Tegner activity scale. Test-retest reliability was measured in a group of 122 patients at least two years after they had undergone surgery for a meniscal lesion. This group completed a follow-up form and then completed it again within four weeks. The other tests were performed in a group of 191 patients who had only a meniscal lesion at the time of the surgery and a group of 477 patients who had a meniscal lesion and other intra-articular lesions.

Results: The overall Lysholm score showed acceptable test-retest reliability, floor and ceiling effects, criterion validity, construct validity, and responsiveness to change. There were unacceptable ceiling effects (>30%) for the Lysholm domains of limp, instability, support, and locking. The Tegner activity scale showed acceptable test-retest reliability, floor and ceiling effects, criterion validity, construct validity, and responsiveness to change.

Conclusions: Overall, the Lysholm knee score and the Tegner activity scale demonstrated acceptable psychometric performances as outcome measures for patients with a meniscal injury of the knee. Some domains of the Lysholm score showed suboptimal performance, and the Tegner scale had only a moderate effect size. Psychometric testing of other condition-specific knee instruments for patients with a meniscal lesion of the knee would be helpful to allow comparison of the properties of the various knee instruments.