Magnetic Resonance Imaging in the Diagnosis of Osteoarthritis of the Knee

Background:

To define changes of a knee joint of patients with osteoarthritis on the basis of MRI data.

Patients and Methods:

The study included 40 patients (28 women, 12 men, aged between 40-80 years, 20 persons in the control group). The MRI study of the knee joint comprised coronary, axial and sagittal projections, in T1 and T2 modes. Evaluating the quality and quantity indicators of cartilage: clearness and sharpness of edges of a cartilage, its thickness on medial and lateral condyles and the intercondylar fossa. We studied the contours of the bony structures of the femur and tibia, the condition of the joint space, and the presence of effusion as well. The shape, integrity, contour, and position of the menisci were also evaluated. The type of injury inflicted on the menisci, frequency of internal and external meniscus injury and the location of the tear were also assessed. X-ray of the knee was performed in two standard projections the Kellgren-Lawrence criteria were applied for staging of the osteoarthritis.

Results:

In 23% of patients, imaging revealed an uneven thinning of the articular cartilage of less than 2 mm. Radiologically degenerative and proliferative changes of bone structures were not found in this group of patients. In 38% of patients, thickness of the hyaline cartilage was observed to have declined to 1 mm. Single sites of destruction of an articular cartilage, synovitis, a meniscus prolapse on 1/3 of its width and injury of a meniscus in 50% of cases were found. In these patients, radiological findings showed unexpressed osteophytes and line osteosclerosis. In 27% of patients with hyaline cartilage thickness of less than 1 mm, expressed destruction of articular cartilage, synovitis, a full prolapse of a meniscus with deformation of its internal part and injury of a meniscus in 70% of cases was observed. The frontal and posterior horns of the menisci were damaged in 40% and 33%, of patients correspondingly. The body of meniscus was damaged in 18.4% of patients. Complex tear with extension to the body or to the other horn was noted in 1.6% of patients. In 76.5% of patients, horizontal tear in menisci was found. Complex and radial fractures occurred in 16.2% of cases and paracapsular rupture was found in 7% of them. In degenerative changes of menisci heterogeneity, fragmentation and cysts were noted. The intra-articular effusion led to the emergence of Baker's cysts in 53% of patients. Expressed osteophytes, joint space narrowing and expressed osteosclerosis were revealed. In 12% of patients, on MRI, image of the articular cartilage was absent. Radiological findings in these patients included large marginal osteophytes, significant narrowing of joint space and expressed subchondral osteosclerosis.

Conclusions:

Magnetic resonance imaging may reveal specific changes of arthritis in articular cartilage at an early stage and more precisely characterize the features and extent of changes in joint structures in the process of disease development.