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Defining the Minimal Clinically Important Difference and Patient Acceptable Symptom State for Isolated Microfracture
Rodrigo Saad Berreta1, Zeeshan A Khan2, Sachin Allahabadi3
1Department of Orthopedics, Rush University Medical Center, Chicago, Illinois, USA.
Background:
There is a paucity of literature regarding the long-term clinical significance and patient-reported outcome measures (PROMs) after isolated microfracture of the knee for cartilage defects.
Purposes:
To (1) define the minimally clinically important difference (MCID) and patient acceptable symptom state (PASS) thresholds for knee microfracture at a minimum 5-year follow-up, and (2) investigate predictive factors-including preoperative, demographic, and intraoperative variables-to achieve MCID and PASS.
Study Design:
Case-control study; Level of evidence, 3.
Methods:
All patients who underwent isolated microfracture for knee chondral defects from 2013 to 2018 were retrospectively identified through a prospectively-maintained institutional database. MCID thresholds were determined by a distribution-based method, while PASS thresholds were established using an anchor-based method. The PROMs analyzed included the International Knee Documentation Committee (IKDC) score and the Knee injury and Osteoarthritis Outcome Score (KOOS). Multivariate logistic regression was performed to identify factors associated with achieving the MCID and PASS thresholds.
Results:
A total of 70 patients were included in the study. The thresholds for MCID achievement and achievement rates were as follows: IKDC, 11.13 (68.57%); KOOS activities of daily living (ADL), 10.56 (65.71%); KOOS Pain, 9.83 (72.86%); KOOS quality of life (QoL), 14.47 (67.14%); KOOS Sport, 14.65 (68.57%); and KOOS Symptoms, 9.95 (58.57%). The thresholds for PASS achievement and achievement rates were as follows: IKDC, 67.24 (58.57%); KOOS ADL, 96.31 (44.29%); KOOS Pain, 85.54 (51.43%); KOOS QoL, 56.38 (55.71%); KOOS Sport, 57.41 (55.71%); and KOOS Symptoms, 76.74 (54.29%). A lower preoperative score was predictive of achieving the MCID for the IKDC and each KOOS subscale. A Kellgren-Lawrence (K-L) grade of 0 or 1 was predictive of achieving the PASS for the IKDC, KOOS Pain, and KOOS Symptoms. A lower body mass index (BMI) was predictive of achieving the PASS for the KOOS ADL and the KOOS Pain, in addition to attaining the MCID for the KOOS ADL, KOOS Pain, and KOOS Sport. A lesion size of <2 cm2 was predictive of achieving the MCID for the IKDC and the KOOS Sport.
Conclusion:
This study defines the thresholds for MCID and PASS achievement at a minimum 5-year follow-up for patients undergoing isolated microfracture of the knee. Patient-specific and defect-specific factors associated with MCID and PASS achievement included lower BMI, younger age, male sex, lower K-L grade, and smaller lesion sizes.
Insights
This study established long-term outcome thresholds for knee microfracture, finding that lower BMI, younger age, and smaller lesion sizes predict better patient-reported outcomes. These factors are crucial for achieving minimally clinically important difference (MCID) and patient acceptable symptom state (PASS).
Area of Science:
- Orthopedic surgery
- Regenerative medicine
- Sports medicine
Background:
- Limited data exists on long-term clinical significance and patient-reported outcome measures (PROMs) following isolated knee microfracture for cartilage defects.
- Understanding these outcomes is crucial for managing patient expectations and guiding treatment decisions.
Purpose of the Study:
- To define the minimally clinically important difference (MCID) and patient acceptable symptom state (PASS) thresholds for knee microfracture at a minimum 5-year follow-up.
- To identify preoperative, demographic, and intraoperative factors that predict achieving MCID and PASS.
Main Methods:
- A retrospective case-control study (Level of evidence, 3) identified 70 patients who underwent isolated knee microfracture.
- MCID and PASS thresholds were determined using distribution-based and anchor-based methods, respectively.
- International Knee Documentation Committee (IKDC) and Knee injury and Osteoarthritis Outcome Score (KOOS) PROMs were analyzed; multivariate logistic regression identified predictive factors.
Main Results:
- Established MCID thresholds for IKDC (11.13) and KOOS subscales (e.g., ADL 10.56, Pain 9.83).
- Established PASS thresholds for IKDC (67.24) and KOOS subscales (e.g., ADL 96.31, Pain 85.54).
- Lower preoperative scores, lower body mass index (BMI), lower Kellgren-Lawrence (K-L) grade (0 or 1), and smaller lesion size (<2 cm²) were predictive of achieving MCID and/or PASS.
Conclusions:
- This study provides crucial MCID and PASS thresholds for isolated knee microfracture at a minimum 5-year follow-up.
- Predictive factors for successful outcomes include patient-specific (lower BMI, younger age, male sex) and defect-specific (lower K-L grade, smaller lesion size) variables.