Large variability in minimal clinically important difference, substantial clinical benefit and patient acceptable symptom state values among literature investigating patellar stabilization surgery: A systematic review.

purposeTo investigate minimal clinically important difference (MCID), substantial clinical benefit (SCB), patient acceptable symptom state (PASS) values for patient-reported outcome measures (PROMs) after patellar stabilization surgery for patellar instability. Secondary outcomes included to describe methods to calculate clinically significant outcomes (CSOs), and to report on the achievement of these metrics.

methodsOn 31 July 2024, three databases were searched. Information on whether studies calculated MCID, SCB or PASS values or used previously established values was recorded. Data on study characteristics, CSO values, and the method of MCID quantification (e.g., distribution vs. anchor) were extracted.

resultsA total of 17 articles with 1447 patients (1462 knees) were included. A total of 18 unique outcome measures were reported. Six out of 15 (40%), 2 out of 5 (40%), and zero studies used prior established values for MCID, SCB and PASS, respectively. MCID ranged widely (e.g., International Knee Documentation Committee [IKDC]: 5.6-20.5; Kujala Anterior Knee Pain Scale: 5.38-11.9 and Lysholm: 5.6-11.1). Fourteen out of 15 utilized a distribution-based method to calculate MCID, with only one study using an anchor-based method. SCB values ranged widely as well (e.g. , IKDC: 14.5-23.6; Knee Osteoarthritis and Outcome Score [KOOS] symptoms: 4.2-14.2 and KOOS activities of daily living [ADLs]: 6.5-25.7). Large variability was found among percentages of patients that achieved MCID values (e.g. , IKDC: 28%-98.6%, Kujala: 38%-100%, Lysholm: 44%-98.4% and Tegner: 84%-95%).

conclusionThe significant heterogeneity in reported thresholds for MCID, SCB and PASS across studies highlights critical challenges in interpreting results after patellar stabilization surgery, specifically regarding what constitutes a clinically relevant outcome. MCID was the most commonly reported metric and calculated predominantly with distribution-based methods, with over half of the studies using previously established thresholds. PASS and SCB were widely underreported as well, suggesting a need for studies investigating patellar stabilization to prioritize the calculation of all three metrics, using anchor-based techniques. LEVEL OF EVIDENCE: Level IV.