Low correlation between functional performance and patient reported outcome measures in individuals with non-surgically treated ACL injury

OBJECTIVE: Describe a consecutive cohort of people with a non-surgically treated ACL injury and evaluate correlations between functional performance and patient reported outcome measures (PROMs). DESIGN: Cross-sectional. PARTICIPANTS: Sixty-eight individuals (38 males, 18-45 years old) 2-5 years after ACL injury. MAIN OUTCOME MEASURES: Tegner Activity Scale, International Knee Documentation Committee Subjective Knee Form (IKDC-SKF), Anterior Cruciate Ligament Return to Sport after Injury scale (ACL-RSI) and ACL-Quality of Life (ACL-QoL) were completed. Functional performance was assessed using 4 hop tests and a squat test. RESULTS: Mean IKDC-SKF score was 72 ± 17 and mean LSI on performance tests were above 90%. Tegner Activity Scale was reduced from median 8 pre-injury to 5 at follow up. Satisfaction with activity level was median 7 on a 10-point ordinal scale. Correlations were moderate to strong (r = 0.552-0.856) between PROMs, negligible to weak (r = 0.003-0.403) between performance tests and PROMs and negligible to moderate (r = 0.142-0.683) between performance tests. CONCLUSION: Functional performance had negligible or weak correlation to PROMs, which indicates the need for multi-modal assessment strategies. Activity level was reduced 2-5 years after a non-surgically treated ACL injury, but most patients were able to resume physical activity at a sufficient level to maintain health and displayed symmetrical functional performance. LEVEL OF EVIDENCE: Retrospective cohort study, Level III.