Initial Validation of a Modified MRI Scoring System for Assessing Outcomes after Single-Surface Osteochondral Shell Allograft Transplantation in the Knee.

Abstract

The Osteochondral Allograft Magnetic Resonance Imaging Scoring System (OCAMRISS) provides a reproducible method for imaging-based grading for osteochondral allograft (OCA) transplants. However, the OCAMRISS does not account for larger whole-surface OCA shell grafts, and has not been validated for assessing outcomes after shell OCA transplantation. Therefore, the objective of this study was to evaluate a modified OCAMRISS for assessing single-surface shell OCAs in the knee based on strength of correlations for a modified OCAMRISS score with graft success and patient-reported outcomes for pain and function. With institutional review board approval and informed patient consent, patients who underwent large single-surface shell OCA transplantation and magnetic resonance imaging (MRI) exams at 1-year postsurgery were identified from a prospectively enrolled registry. All patients with a minimum of 2 years of clinical follow-up were included in the present study. A modified OCAMRISS, as well as assessment of the percentage of OCA bone incorporation, was used to score each knee. Two radiologists, blinded to patient demographics and outcomes, reviewed all MRIs together to determine a consensus score for each category and %-incorporation for each OCA. Thirteen patients (7 F, 6 M; mean age = 29.8 ± 9.4; mean body mass index = 27.1 ± 5.8); 8 medial femoral condyle, 4 patella, and 1 medial tibial plateau shell OCAs were evaluated. Mean modified OCAMRISS score was 5.2 ± 2.8, range (2-12) and %-integration was 72.7 ± 33.8, range (0-100). Moderate to strong correlations were noted for 1-year modified OCAMRISS total score with final follow-up (FFU) visual analog scale (VAS) pain (r = +0.58) and Single Assessment Numeric Evaluation (SANE) function (r = -0.7) scores, and for 1-year %-incorporation with FFU VAS pain (r = -0.76) and SANE function (r = +0.83) scores. The modified OCAMRISS total score and %-incorporation assessments determined at 1 year following single-surface shell OCA transplantation correlate well with initial patient outcomes and have clinical applicability for monitoring patients after large-shell OCA transplants in the knee.