Ultrasound signs of joint pathology

Joint effusion (synovitis). Characterized by thickening and swelling of the synovial membrane. The first sign of synovial membrane inflammation is increased production of synovial fluid - joint effusion. Joint effusion can be observed in various diseases of the musculoskeletal system: degenerative, traumatic, inflammatory, tumor. The nature of the contents can only be determined after aspiration of the fluid. During ultrasound examination, the fluid in the joint cavity varies in echogenicity. Thus, with ordinary synovitis, the fluid is anechoic, with hemarthrosis and lipohemarthrosis - heterogeneous, hypoechoic, with echogenic inclusions (blood clots, fat lobules).

MRI is a method for detecting synovitis. Inflammatory changes are characterized by thickening of the membrane and increased water content. Therefore, the synovial membrane appears as thickened hyperintense tissue on T2-weighted images or on images obtained with a STIR sequence.

Septic arthritis. Characterized by the presence of heterogeneous fluid in the joint cavity, which is sometimes divided into separate levels. Hypertrophy of the synovial membrane is also noted. This symptom occurs in rheumatoid arthritis, inflammatory arthritis, synovial chondromatosis and other diseases. Ultrasound examination is invaluable in monitoring the treatment of septic arthritis.

Traumatic meniscus injuries. Most often, we encounter meniscus injuries of the knee joint. During ultrasound examination, the meniscus tear line looks like a hypoechoic strip against the background of a hyperechoic meniscus). The tissue harmonic mode improves the visualization of meniscus tears due to better elaboration of echo structures. With three-dimensional volumetric reconstruction, it is possible to obtain images of meniscus injuries comparable to arthroscopic ones.

Changes in hyaline cartilage can manifest themselves in three forms: thinning, thickening and calcification.

Degenerative changes of the meniscus. Often observed in elderly patients. The meniscus may have a non-uniform structure, decreased echogenicity, and bulge above the articular surface. On arthroscopy, these changes are manifested by a non-uniform bulging of the meniscus surface with mucoid degeneration.

Thickening of the hyaline cartilage due to edema is the earliest sign of pathological changes in the joint. Later, the cartilage surface becomes uneven and cartilage thinning occurs. Comparison of cartilage thickness with the contralateral side helps in identifying these early changes.

Thinning of hyaline cartilage. Normally, in elderly people, hyaline cartilage becomes thinner. A similar process occurs with inflammatory synovitis, septic arthritis. Degenerative changes in hyaline cartilage can be detected by ultrasound examination in the form of its local thinning or ulceration. Changes in hyaline cartilage are also accompanied by changes in bone tissue, the articular surface of which becomes uneven.

Joint mouse. Quite often encountered various inclusions in the joint cavity or in the synovial membrane. The sizes can vary from small inclusions to large ones.

Meniscus cysts. Occur as a result of constant trauma to the meniscus. They appear as an anechoic rounded formation in the thickness of the meniscus. Cysts of the outer meniscus are observed more often. Behind the cyst, there is an effect of distal amplification of the echo signal, which contributes to better visualization of the apex of the meniscus.

Osteophytes. Osteophytes initially appear at the joint margins at the junction of the hyaline cartilage and cortical bone. They are cartilaginous growths (chondrophytes) that eventually undergo enchondral ossification and are seen on radiographs as osteophytes. Small marginal osteophytes are a common finding in older people as they are a mechanism for stabilizing the joint. Large osteophytes are considered part of the osteoarthritic process.

Deforming arthrosis. This is a degenerative-dystrophic lesion of the joint with a violation of the shape of the articulating ends of the bones, articulating surfaces, violation of the height and shape of the radiographic joint space. Hypodynamia, obesity, hypoxia lead to the occurrence of increased load on the joint and, as a consequence, contribute to the development of deforming arthrosis. Initially, due to dynamic load and irritation, the articular cartilage is affected: it thickens. Then there is disorganization and thinning of the hyaline cartilage, compensatory bone-cartilaginous growths appear along the edges. In parallel, changes occur in the bone tissue of the epiphysis, the shape of the articular ends of the articulating bones changes. Significant changes are undergone by the joint capsule, ligaments, synovial membrane. The joint capsule thickens to stabilize the joint. Synovial outgrowths, sometimes of cartilaginous density, are formed in the synovial membrane, which, pinching off, form intra-articular bodies. Intra-articular ligaments thicken, loosen, can become necrotic, and fuse with the capsule. The amount of synovial fluid increases in the early stages to improve sliding in the joint, and then decreases, aggravating the dystrophic process. Fibrosis gradually develops in the form of intra-articular adhesions, compaction of para-articular tissues, which sharply limits mobility in the joint.

Gout. A disease caused by purine metabolism disorders, leading to increased uric acid levels in the blood and urate deposition in tissues. The most striking manifestations of gout are acute arthritis, which is characterized by sudden onset, localization in the area of the metatarsophalangeal joints of the first toes, pronounced clinical symptoms and rapid onset of remission. Exacerbation of acute arthritis is provoked by: trauma, alcohol, fatty foods, psychoemotional stress, use of diuretics, etc. Long-term gout is characterized by the development of granulation tissue in the form of pannus, causing destruction of articular cartilage, subchondral bone and, in rare cases, ankylosis of the joint. Ultrasound examination reveals the appearance of a hypoechoic zone surrounded by a fibrous capsule around the joint. Ultrasound angiography in the acute stage reveals pronounced tissue vascularization.

In the subchondral bone, where urates are deposited, secondary changes occur such as microfractures with the formation of fibrous and bone calluses, the development of cysts and osteosclerosis. Extra-articular localization is much less common: dermatitis, tenosynovitis, bursitis, myositis. With the transition to the chronic stage, patients constantly experience inflammation of one or more joints. Tophi are deposited in the area of the affected joint, as a result of which the periarticular tissues thicken, and mobility in the joint is impaired. Tophi can be from 2-3 mm to 2-3 cm in size, in the form of nodular formations located close to the surface of the skin. During ultrasound examination, they look like round or oval hypoechoic formations of various sizes in the thickness of the skin and subcutaneous tissue. Due to osteolysis, gross deformation of the joints is observed. The joint damage is asymmetric.