Development of a Comprehensive Osteochondral Allograft MRI Scoring System (OCAMRISS) With Histopathologic, Micro–Computed Tomography, and Biomechanical Validation

Abstract

Objective:To describe and apply a semiquantitative MRI scoring system for multifeature analysis of cartilage defect repair in the knee by osteochondral allografts and to correlate this scoring system with histopathologic, micro–computed tomography (µCT), and biomechanical reference standards using a goat repair model.Design:Fourteen adult goats had 2 osteochondral allografts implanted into each knee: one in the medial femoral condyle and one in the lateral trochlea. At 12 months, goats were euthanized and MRI was performed. Two blinded radiologists independently rated 9 primary features for each graft, including cartilage signal, fill, edge integration, surface congruity, calcified cartilage integrity, subchondral bone plate congruity, subchondral bone marrow signal, osseous integration, and presence of cystic changes. Four ancillary features of the joint were also evaluated, including opposing cartilage, meniscal tears, synovitis, and fat-pad scarring. Comparison was made with histologic and µCT reference standards as well as biomechanical measures. Interobserver agreement and agreement with reference standards was assessed. Cohen’s κ, Spearman’s correlation, and Kruskal-Wallis tests were used as appropriate.Results:There was substantial agreement (κ > 0.6, P < 0.001) for each MRI feature and with comparison against reference standards, except for cartilage edge integration (κ = 0.6). There was a strong positive correlation between MRI and reference standard scores (ρ = 0.86, P < 0.01). Osteochondral allograft MRI scoring system was sensitive to differences in outcomes between the types of allografts.Conclusions:We have described a comprehensive MRI scoring system for osteochondral allografts and have validated this scoring system with histopathologic and µCT reference standards as well as biomechanical indentation testing.

Macroscopic cartilage repair scoring of defect fill, integration and total points correlate with corresponding items in histological scoring systems – a study in adult sheep

“…Future studies may also focus on different anatomical defect locations as e.g., the femoral trochlea 32 , and animal models 33 . Moreover, indentation testing offers complementary functional information, allowing also to evaluate the quality of the repair tissue or its integration strength 34 . Correlating this specific analytical method with macroscopic assessment and histological grading of cartilage repair will further validate these scoring systems and lead to an improved understanding of cartilage repair.…”

Osteochondral allograft transplantation in cartilage repair: Graft storage paradigm, translational models, and clinical applications

“…Thus, we were motivated by the need for non‐invasive characterization of OCA and the ability to refine MRI technology to predict clinical outcomes. We introduced a comprehensive MRI scoring system for OCA and validated such scoring system with histopathologic, μCT, and biomechanical reference standards in an adult goat model of in vivo OCA repair with variable treatment options, ranging from outstanding to poor repair . Nine primary features for each graft (including, cartilage signal, fill, lateral integration, surface congruity, calcified cartilage integrity, subchondral bone plate congruity, subchondral bone signal, osseous integration, and presence of cystic changes) and four ancillary features of the joint (including, opposing cartilage, meniscal tears, synovitis, and fat‐pad scarring) were defined for an accurate description of in vivo repair, which may help standardize reporting of MR findings after OCA repair.…”

Cartilage restoration of the hip using fresh osteochondral allograft

“…For those patients with post-operative MRI, the Osteochondral Allograft MRI Scoring System (OCAMRISS) 19 was used to assess the allograft using coronal T1-weighted FSE images. The OCAMRISS is a comprehensive MRI score that incorporates analysis of five cartilage features including cartilage signal, fill, cartilage edge integration with host, and calcified cartilage integrity, four bone features including subchondral bone plate congruity, subchondral bone marrow signal, osseous integration at the host-graft junction, and presence of cystic changes at the host-graft junction, and four ancillary features.…”