Defining the Minimal Clinically Important Difference and Patient Acceptable Symptom State for Microfracture of the Knee: A Psychometric Analysis at Short-term Follow-up

Abstract

Background: Several studies have investigated failure rates and magnitude of improvement in patient-reported outcome measures after microfracture surgery for focal chondral defects of the knee; however; what constitutes clinically significant improvement in this patient population is poorly understood. Purpose: To (1) establish the minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) thresholds for microfracture surgery including the time-dependent nature of these thresholds and (2) identify predictors of achieving the MCID and PASS in patients specifically undergoing microfracture of the knee. Study Design: Case series; Level of evidence, 4. Methods: A secure institutional cartilage preservation repository was queried for all patients who underwent microfracture between 2004 and 2017. The distribution method was used to calculate MCID thresholds for the International Knee Documentation Committee (IKDC) score and the Knee injury and Osteoarthritis Outcome Score (KOOS), whereas an anchor-based method was used for the PASS. Multivariate logistic regressions were constructed to determine predictors of achieving the MCID and PASS. Results: A total of 206 patients with a mean ± SD age of 33.7 ± 13.2 years and body mass index of 26.9 ± 5.3 kg/m2 were included. All thresholds for the MCID and PASS increased over time except for the MCID thresholds for the KOOS Sports and Symptoms subscales. The proportion of patients who achieved the MCID (6 months, 78.4%; 12 months, 83.9%; 24 months, 88.6%) and PASS (6 months, 67.7%; 12 months, 79.2%; 24 months, 76.1%) generally increased over time. Older age and larger lesion size were negative independent predictors of MCID achievement. Older age was also a negative predictor of the PASS, whereas male sex and higher preoperative KOOS Symptoms and Pain scores were positive independent predictors of the PASS. Conclusion: The MCID and PASS thresholds for the IKDC and KOOS in patients undergoing microfracture of the knee are dynamic, with an increasing number of patients achieving the MCID over time. The percentage achieving the PASS increased between 6 and 12 months and then declined slightly at 24 months. Independent predictors of achieving the MCID were lesion size and age at surgery, whereas predictors of achieving the PASS included lesion size, male sex, and greater preoperative KOOS Symptoms and Pain scores.

Minimal Clinically Important Difference and Patient Acceptable Symptom State in Patients With Knee Osteoarthritis Treated With PRP Injection

“…The MCID was calculated using the distribution method derived from the value equal to half of the standard deviation of the overall cohort improvement at 6 and 12 months. 7 , 21 , 25 , 28 Patients were classified as achieving the MCID if it was achieved in ≥1 of the included outcome measures, as previously described. 7 The PASS was calculated through use of an anchor-based method by asking the patients whether their current state was satisfactory or not through the following question: “Taking into account all the activities of daily life, the level of pain and the functional impairment, are you satisfied with your knee health status?” as previously described.…”

“… 7 , 21 , 25 , 28 Patients were classified as achieving the MCID if it was achieved in ≥1 of the included outcome measures, as previously described. 7 The PASS was calculated through use of an anchor-based method by asking the patients whether their current state was satisfactory or not through the following question: “Taking into account all the activities of daily life, the level of pain and the functional impairment, are you satisfied with your knee health status?” as previously described. 7 , 12 , 21 , 22 , 25 The PASS was assessed using a 2-point scale ( satisfied or not satisfied ), and threshold values were detected through a receiver operating characteristic (ROC) curve analysis and the Youden index in such a way as to maximize the sensitivity and the specificity of the threshold values.…”

“… 7 The PASS was calculated through use of an anchor-based method by asking the patients whether their current state was satisfactory or not through the following question: “Taking into account all the activities of daily life, the level of pain and the functional impairment, are you satisfied with your knee health status?” as previously described. 7 , 12 , 21 , 22 , 25 The PASS was assessed using a 2-point scale ( satisfied or not satisfied ), and threshold values were detected through a receiver operating characteristic (ROC) curve analysis and the Youden index in such a way as to maximize the sensitivity and the specificity of the threshold values. The area under the curve (AUC) of the ROC analysis was used to evaluate the ability of the identified PASS threshold values to differentiate between satisfied and unsatisfied patients.…”

“…The MCID is defined as the smallest difference in a specific PROM score that patients perceive as beneficial, referring to the amount of absolute change in a PROM score that relates to a clinical improvement, while the PASS defines a level of symptoms that discriminate between feeling well and feeling unwell. 21 , 23 These 2 psychometric measures for the IKDC and the KOOS have been reported in patients undergoing orthopaedic surgical procedures (eg, microfracture or meniscal allograft transplantation 6 , 7 , 25 ); however, their threshold when assessing the clinical relevance of injection-based treatments for knee OA is yet to be defined.…”

Studies of Articular Cartilage Repair from 2009 to 2018: A Bibliometric Analysis of Articles

“…Rapid advances in tissue regeneration technologies, such as stem cell-based technologies 3,4 , tissue-engineered scaffolds 5,6 , and three-dimensional (3D) bioprinting 7,8 , others, have been made in the past decade, owing to their potential to heal damaged articular cartilage. Traditional treatment methods, including microfracture 9,10,11 , osteochondral transplantation 12,13,14 , and chondrocyte implantation 15,16,17 , can relieve pain and improve joint function. However, these methods are unable to fully prevent cartilage degeneration and restore the desired biomechanical properties of tissues 18,19 .…”