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Purpose: To evaluate the diagnostic effectiveness of magnetic resonance (MR) in knee cartilage pathologies of different regions and grades with the aim of establishing the role of MR in treatment choice., Materials and Methods: We enrolled 90 patients who underwent MR and arthroscopy of the knee. To classify cartilage lesions we used a simplified grading system that correlates MR to arthroscopic reports and divides lesions into low and high grades. The MR examinations were performed with a 1.5 T superconducting magnet with a standard protocol to obtain quality images in a short time, using T1-weighted spin-echo sequences, T2* weighted gradient-echo sequences and inversion recovery sequences. The MR diagnostic specificity, sensitivity and accuracy and MR positive predictive value and negative predictive value in identifying and grading the chondral lesions of the femorotibial and patellofemoral compartments were calculated and compared to arthroscopy parameters., Results: The analysis of each grade of chondral lesions reveals an MR accuracy of 94% in high-grade lesions of the femorotibial and patellofemoral compartments and an MR accuracy of 78% in low-grade lesions of patellofemoral compartment and of 70% in low-grade lesions of femorotibial compartment. This result suggests MR is useful for the grading of chondral lesions in clinical practice., Conclusions: MR diagnostic effectiveness substantially changes according to the different location and grade of chondral lesions. While MR seems to be nearly equivalent to arthroscopy for high-grade lesions subject to surgery, it appears to be less accurate in diagnosing low-grade lesions, in particular femorotibial lesions.

Purpose: Juvenile patellar chondromalacia is a common orthopedic disorder which can mimic other conditions; early diagnosis is mandatory to prevent its evolution into osteoarthrosis. In the early stages of patellar chondromalacia (I and II), the lesions originate in the deep cartilage layer and the joint surface is not affected. Arthroscopy can demonstrate joint surface changes only and give indirect information about deeper lesions. We investigated the yield of 2D FLASH MRI with 30 degrees flip angle and a dedicated coil in the diagnosis of patellar chondromalacia, especially in its early stages., Material and Methods: Eighteen patients (mean age: 21 years) with clinically suspected patellar chondromalacia were examined with MRI; 13 of them were also submitted to arthroscopy. A 1.5 T unit with a transmit-and-receive extremity coil was used. We acquired T1 SE sequences (TR/TE: 500-700/15/20) and 2D T2* FLASH sequence (TR/TE/FA: 500-800/18/30 degrees). The field of view was 160-180 mm and the matrix 192 x 256, with 2-3 NEX. The images were obtained on the axial plane. The lesions were classified in 4 stages according to Shahriaree classification., Results: Agreement between MR and arthroscopic findings was good in both early and advanced lesions in 12/13 cases. Early lesions appeared as hyperintense focal thickening of the hyaline cartilage (stage I) or as small cystic lesions within the cartilage and no articular surface involvement (stage II). The medial patellar facet was the most frequent site. Advanced lesions appeared as articular surface ulcerations, thinning and cartilage hypointensity (stage III); stage IV lesions presented as complete erosions of the hyaline cartilage and hypointense underlying bone., Conclusions: 2D FLASH MRI with 30 degrees flip angle can show the differences in water content in the cartilage and thus permit to detect early chondromalacia lesions in the deep cartilage.

Magnetic Resonance Imaging (MRI) shows, in the post-traumatic knee, a fairly high number of bone and cartilage injuries missed by conventional radiography and therefore called occult. Our aim is to classify these injuries, to correlate their site and distribution with associated menisco-ligamentous injuries and with trauma mechanisms. Thirty-eight patients with a history of acute knee trauma and negative X-ray findings were examined with MRI within 15 days of trauma. 1.5- and 0.5-T units and SE T1-weighted GE T2*-weighted and SE T2-weighted sequences were used. The injuries were classified as intraosseous and osteochondral bruises or fractures. Twenty-three patients with menisco-ligamentous injuries were submitted to therapeutic arthroscopy; the sites of bone and cartilage injuries depicted with MRI were studied with arthroscopy. Seven patients were followed-up with MRI at 6-12 months to investigate subchondral injury evolution: 5 of 7 patients were also submitted to arthroscopy. MRI showed a statistically significant correlation between site and distribution of bone and cartilage injuries and between internal derangement and trauma mechanisms, i.e., contusion, distortion, stress. In our experience, MRI could identify and characterize occult subchondral injuries, thus allowing appropriate treatment.