The meniscal and bone evaluation was performed using the same sequences as for the cartilage assessment, as previously discussed [14 (link)]. Regardless, the FISP sequence enabled us to visualize the meniscal tissue and bone lesions with enough clarity to adequately and reliably perform the semi-quantitative scoring system [14 (link)]. A semi-quantitative lesion assessment of meniscal damage and bone edema was performed. Knee menisci and bone lesions were evaluated by an experienced radiologist (MJB) who was blinded to the time sequences and cartilage volumes, while the cartilage volume assessment was performed separately by two different readers who were blinded to the radiologist's grading.
Our scoring system for meniscal damage referred to the accepted MRI nomenclature for meniscal anatomy, which is in accordance with arthroscopic literature [25 ,26 ]. The proportion of the menisci affected by degeneration, tear, or extrusion was scored separately using the following semi-quantitative scale [14 (link)]: 0 = no damage; 1 = 1 out of 3 meniscal areas involved (anterior, middle, posterior horns); 2 = 2 out of 3 involved; 3 = all 3 areas involved. The extent of meniscal extrusion on the medial or lateral edges of the femoral tibial joint space, not including the osteophytes, was evaluated for the anterior, middle, and posterior horns of the menisci in which 0 = no extrusion, 1 = partial meniscal extrusion, and 2 = complete meniscal extrusion with no contact with the joint space.
For bone edema, the intensity and extent of the lesion was assessed in the medial and lateral tibio-femoral compartments with the following semi-quantitative scale: 0 = absence of edema; 1 = mild to moderate edema, meaning a small or medium-sized lesion; and 2 = severe edema, meaning a large one. The results are presented by either presence or absence of any edema (grade 1 or 2) and presence or absence of one severe edema lesion (grade 2 only), regardless of the presence of additional smaller lesions.
Reliability of our scoring system for meniscal and bone changes was excellent. The intra- and inter-reader correlation coefficient ranged from 0.86 to 0.96 for the meniscal tear, 0.85 to 0.92 for the meniscal extrusion and 0.88 to 0.93 for the bone marrow edema. Kappa statistics ranged from 0.79 to 0.89 for the meniscal changes and 0.78 to 0.87 for the bone marrow edema (data not shown).
Our scoring system for meniscal damage referred to the accepted MRI nomenclature for meniscal anatomy, which is in accordance with arthroscopic literature [25 ,26 ]. The proportion of the menisci affected by degeneration, tear, or extrusion was scored separately using the following semi-quantitative scale [14 (link)]: 0 = no damage; 1 = 1 out of 3 meniscal areas involved (anterior, middle, posterior horns); 2 = 2 out of 3 involved; 3 = all 3 areas involved. The extent of meniscal extrusion on the medial or lateral edges of the femoral tibial joint space, not including the osteophytes, was evaluated for the anterior, middle, and posterior horns of the menisci in which 0 = no extrusion, 1 = partial meniscal extrusion, and 2 = complete meniscal extrusion with no contact with the joint space.
For bone edema, the intensity and extent of the lesion was assessed in the medial and lateral tibio-femoral compartments with the following semi-quantitative scale: 0 = absence of edema; 1 = mild to moderate edema, meaning a small or medium-sized lesion; and 2 = severe edema, meaning a large one. The results are presented by either presence or absence of any edema (grade 1 or 2) and presence or absence of one severe edema lesion (grade 2 only), regardless of the presence of additional smaller lesions.
Reliability of our scoring system for meniscal and bone changes was excellent. The intra- and inter-reader correlation coefficient ranged from 0.86 to 0.96 for the meniscal tear, 0.85 to 0.92 for the meniscal extrusion and 0.88 to 0.93 for the bone marrow edema. Kappa statistics ranged from 0.79 to 0.89 for the meniscal changes and 0.78 to 0.87 for the bone marrow edema (data not shown).
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