Minimal Clinically Important Difference and Patient Acceptable Symptom State Thresholds After Anterior Cruciate Ligament Reconstruction Vary Considerably Across Published Studies: A Systematic Review

Purpose To identify and summarize reported clinically significant outcome threshold values across commonly used patient‐reported outcome measures in patients undergoing anterior cruciate ligament reconstruction. Methods A systematic literature search was conducted to identify studies published up to July 2025 that reported clinically significant outcome threshold values after anterior cruciate ligament reconstruction using validated patient‐reported outcome measures. Methodological quality was assessed using the Methodological Index for Non‐Randomized Studies. Results A total of 9 studies were included. Reported threshold values varied substantially across patient‐reported outcome measures and studies. For the International Knee Documentation Committee‐Subjective Knee Form, minimal clinically important difference (MCID) thresholds ranged from 9.0 to 10.4, whereas patient acceptable symptom state (PASS) thresholds ranged from 74.2 to 86.8. Across the Knee Injury and Osteoarthritis Outcome Score subdomains, MCID thresholds ranged from 2.5 to 21.9, including 13.9 for pain, 5.4 for symptoms, 5.1 for activities of daily living, 2.5 for sport/recreation, and 21.9 for quality of life. PASS thresholds for Knee Injury and Osteoarthritis Outcome Score subdomains ranged from 57.1 to 100.0, including 88.9 to 95.8 for pain, 57.1 to 94.6 for symptoms, 99.3 to 100.0 for activities of daily living, 75.0 to 82.5 for sport/recreation, and 62.5 to 71.9 for quality of life. Conclusions This systematic review of reported MCID and PASS thresholds after anterior cruciate ligament reconstruction shows considerable variability depending on patient population, method of calculation, and the nature of questions asked. This shows that previously published MCID and PASS values are not necessarily applicable in subsequent studies, and the calculation of cohort‐specific thresholds is important. Level of Evidence Level IV, systematic review of Level II to IV studies.