Clinically Meaningful Improvement After Treatment of Cartilage Defects of the Knee With Osteochondral Grafts

BACKGROUND: Mosaicplasty and fresh osteochondral allograft transplantation (OCA) are popular cartilage restoration techniques that involve the single-stage implantation of viable, mature hyaline cartilage-bone dowels into chondral lesions of the knee. Recently, there has been greater focus on what represents a clinically relevant change in outcomes reporting, and commonly applied metrics for measuring clinical significance include the minimal clinically important difference (MCID) and substantial clinical benefit (SCB). PURPOSE: To define the MCID and SCB after mosaicplasty or OCA for the International Knee Documentation Committee (IKDC) subjective form and Knee Outcome Survey-Activities of Daily Living (KOS-ADL) and to determine patient factors that are predictive of achieving the MCID and SCB after mosaicplasty or OCA. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 3. METHODS: An institutional cartilage registry was reviewed to identify patients who underwent mosaicplasty or OCA. The decision to perform either mosaicplasty or OCA was generally based on chondral defect size. The IKDC and KOS-ADL were administered preoperatively and at a minimum of 2 years postoperatively. Patient responses to the outcome measures were aggregated, and the MCID and SCB of these outcome scores were calculated with anchor-based methods. Multivariate analysis adjusted for age and sex was performed to identify patient factors predictive of achieving the MCID and SCB. RESULTS: Of the 372 eligible patients, 151 (41%) were lost to follow-up, 46 (12%) had incomplete preoperative outcome scores and 2 were treated with OCA of the tibia and therefore excluded. In total, 173 knees were analyzed (n = 173 patients; mean age, 33.0 years; 37% female). Seventy-five (43%) and 98 (57%) knees were treated with mosaicplasty and OCA, respectively. The mean ± SD MCIDs for the IKDC and KOS-ADL were 17 ± 3.9 and 10 ± 3.7, respectively. The SCBs for the IKDC and KOS-ADL were 30 ± 6.9 and 17 ± 3.9, respectively. Univariate analysis demonstrated no association between procedure (mosaicplasty or OCA) and likelihood of achieving the MCID or SCB. In the multivariate analysis, lower preoperative IKDC and KOS-ADL scores, higher preoperative Marx Activity Rating Scale scores, lower preoperative 36-Item Short Form Health Survey pain scores, and a history of ≤1 prior ipsilateral knee surgical procedure were predictive of achieving the MCID and/or SCB. CONCLUSION: These values can be used to define a clinically meaningful improvement for future outcome studies. For surgeons considering mosaicplasty or OCA for their patients, these results can help guide clinical decision making and manage patient expectations before surgery.