Knee Function Assessment in Patients With Meniscus Injury: A Preliminary Study of Reproducibility, Response to Treatment, and Correlation With Patient-Reported Questionnaire Outcomes

BACKGROUND: Outcomes of meniscus surgery are typically assessed with patient questionnaires that help capture symptoms and functional limitations but may not provide an accurate representation of underlying joint health. There are currently no performance-based measures of knee function in patients with symptomatic meniscus injury. PURPOSE: To assess the reproducibility, response to partial meniscectomy, and correlation with patient-reported questionnaire outcomes of novel performance-based knee function tests. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: A battery of 9 tests for activities that require knee movements essential for everyday living was developed. Intra- and interrater reproducibility was assessed in 50 meniscus tear patients completing the battery at 2 preoperative assessments with either the same or different examiners. Response to arthroscopic partial meniscectomy was evaluated in 35 of these patients 6 weeks after surgery. Subjects also completed the Knee Injury and Osteoarthritis Outcome Score (KOOS) and International Knee Documentation Committee (IKDC) questionnaires pre- and postoperatively. RESULTS: The intrarater intraclass correlation coefficients (ICCs) were excellent for all tests (ICC > 0.8). Interrater ICC > 0.8 was observed for step-down, stair descent, star lunges, and timed treadmill travel. Performance on all tests improved significantly with surgery (P < .05), with the greatest improvement in sit-to-stand and stair ascent and descent. A greater percentage response to surgery was seen on questionnaire outcomes (20%-65%) than on performance-based tests (3%-15%). Moderate to poor correlations existed between the KOOS activities of daily living subscale and the performance-based tests (all ICCs ≤ 0.4). CONCLUSION: Performance-based knee function tests demonstrated good reproducibility and responsiveness in patients undergoing partial meniscectomy. CLINICAL RELEVANCE: As both patient perception and functional performance are determinants of patient outcomes, questionnaires and performance-based tests could be used simultaneously to provide complementary data to monitor short- and long-term outcomes after meniscus surgery.