Defining clinically relevant outcome thresholds for pain and function after osteochondral autograft transplantation of the knee

Purpose: To define the minimal clinically important difference (MCID) for measures of pain and function at 2, 5 and 10 years after osteochondral autograft transplantations (OATs).

Methods: Patients undergoing OATs of the knee were identified from a prospectively maintained cartilage surgery registry. Baseline demographic, injury and surgical factors were collected. Patient-reported outcome scores (PROMs) were collected at baseline, 2-, 5- and 10-year follow-up, including the International Knee Documentation Committee (IKDC) score, Knee Outcome Survey Activities of Daily Living Scale (KOS-ADLS), Marx activity scale and Visual Analogue Scale (VAS) for pain. The MCIDs were quantified for each metric utilizing a distribution-based method equivalent to one-half the standard deviation of the mean change in outcome score. The percentage of patients achieving MCID as a function of time was assessed.

Results: Of 63 consecutive patients who underwent OATs, 47 (74.6%) patients were eligible for follow-up (surgical date before October 2021) and had fully completed preoperative PROMs. A total of 39 patients (83%) were available for a minimum 2-year follow-up, with a mean (±standard deviation) follow-up of 5.8 ± 3.4 years. The MCIDs were determined to be 9.3 for IKDC, 2.5 for Marx, 7.4 for KOS-ADLS and 12.9 for pain. At 2 years, 78.1% of patients achieved MCID for IKDC, 77.8% for Marx, 75% for KOS-ADLS and 57.9% for pain. These results were generally maintained through 10-year follow-ups, with 75% of patients achieving MCID for IKDC, 80% for Marx, 80% for KOS-ADLS and 69.8% for pain.

Conclusions: The majority of patients achieved a clinically relevant outcome improvement after OATs of the knee, with results sustained through 10-year follow-up. Patients who experience clinically relevant outcome improvement after OATs in the short term continue to experience sustained benefits at longer-term follow-up. These data provide valuable prognostic information when discussing patient candidacy and the expected trajectory of recovery.

Level of evidence: Level III.