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Ultrasound signs of joint pathology
Last reviewed: 19.10.2021
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Exudation in the joint cavity (synovitis). It is characterized by thickening and edema of the synovial membrane. The first sign of inflammation of the synovial membrane is an increase in the production of synovial fluid - joint effusion. Exudation in the joint cavity can be observed with various diseases of the musculoskeletal system: degenerative, traumatic, inflammatory, tumor. The nature of the contents can be established only after aspiration of the liquid. With ultrasound, fluid in the joint cavity is different in echogenicity. So, with usual synovitis, the fluid is anechogenous, with hemarthrosis and lipohemarthrosis - non-uniform, hypoechoic, with echogenic inclusions (blood clots, lobules of fat).
MRI is a method for detecting synovitis. Inflammatory changes are characterized by thickening of the membrane and increased water content. Therefore, the synovial membrane looks like a thick hyperintense tissue on T2 weighted images or on images obtained with the STIR sequence.
Septic arthritis. It is characterized by the presence in the joint cavity of an inhomogeneous fluid, which is sometimes divided into separate levels. There is also hypertrophy of the synovial membrane. This sign arises with rheumatoid arthritis, inflammatory arthritis, synovial chondromatosis and other diseases. Invaluable help ultrasound examines when monitoring the treatment of septic arthritis.
Traumatic injuries of meniscuses. Most often you have to deal with knee joint meniscus lesions. In ultrasound examination, the line of the meniscus rupture looks like a hypoechoic band in the background of a hyperechoic meniscus). The mode of tissue harmonics improves the visualization of meniscus ruptures due to better processing of echostructures. With three-dimensional volumetric reconstruction, it is possible to obtain meniscus lesions comparable to arthroscopic images.
Changes in hyaline cartilage can be manifested in three forms: thinning, thickening and calcification.
Degenerative changes of the meniscus. It is often observed in elderly patients. The meniscus can have a non-uniform structure, a decreased echogenicity, and bulge above the joint surface. On arthroscopy, these changes are manifested by a non-uniform swelling of the meniscus surface with mucoid degeneration.
Thickening of hyaline cartilage due to edema is the earliest sign of pathological changes in the joint. Later, the surface of the cartilage becomes uneven and thinning of the cartilage appears. Comparing the thickness of the cartilage with the contralateral side helps in identifying these early changes.
Thinning of hyaline cartilage. Normally, the hyaline cartilage is thinner in the elderly. 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.
Articular mouse. Quite often there are various inclusions in the joint cavity or in the synovial membrane. Dimensions can vary from small inclusions to large ones.
Meniscus cysts. They arise as a result of permanent traumatization of menisci. They look like anechogenous rounded formation in the thickness of the meniscus. Cysts of the outer meniscus are often observed. Behind the cyst there is the effect of distal echo enhancement, which helps to better visualize the tip of the meniscus.
Osteophytes. Osteophytes initially appear along the edges of the joint at the border of the hyaline cartilage and cortical bone. They are cartilaginous growths (chondrophytes), which eventually undergo endochondral ossification and are detected on x-rays as osteophytes. Small marginal osteophytes are a common finding in the elderly, as they are the mechanism of joint stabilization. Large osteophytes are considered as part of the process of osteoarthritis.
Deforming arthrosis. This degenerative-dystrophic joint injury with the violation of the shape of the articulating ends of bones, articulating surfaces, a violation of the height and shape of the radiographic joint gap. Hypodinamy, obesity, hypoxia lead to the emergence of increased stress on the joint and, as a consequence, contribute to the development of deforming arthrosis. Initially, due to dynamic stress and irritation, joint cartilage is affected: it thickens. Next comes the disorganization and thinning of the hyaline cartilage, compensatory around the edges there are bone-cartilaginous growths. Parallel changes occur in the bone tissue of the epiphysis, the shape of the articular ends of the articulating bones changes. Significant changes undergo joint capsule, ligament, synovial membrane. The joint capsule thickens to stabilize the joint. In the synovial membrane, synovial outgrowths are formed, sometimes of cartilaginous density, which, when unscrewed, form intraarticular bodies. The intra-articular ligaments thicken, loosen, can necrotize, fuse with the capsule. The amount of synovial fluid in the early stages increases to increase the slip in the joint, and then decreases, exacerbating the dystrophic process. Gradually develops fibrosis in the form of intraarticular fusion, consolidation of pararticular tissue, which severely limits mobility in the joint.
Gout. The disease, caused by violations of purine metabolism, leading to an increase in the level of uric acid in the blood and the deposition of urate in the tissues. The most vivid manifestations of gout are acute arthritis, which is characterized by sudden appearance, localization in the area of metatarsophalangeal joints of the first fingers, pronounced clinic and rapid onset of remission. Exacerbation of acute arthritis provokes: trauma, alcohol, fatty food, psychoemotional load, use of diuretics, etc. The prolonged course of gout is characterized by the development of granulation tissue in the form of pannus, which causes the destruction of articular cartilage, subchondral bone and, in rare cases, ankylosis of the joint. With ultrasound examination around the joint, the appearance of a hypoechoic zone surrounded by a fibrous capsule is noted. With ultrasound angiography in the stage of exacerbation, pronounced vascularization of the tissues is noted.
In the subchondral bone, where urates are deposited, secondary changes take place according to the type of micro fractures with the formation of fibrous and bone calluses, the development of cysts and osteosclerosis. Significantly, extra-articular localization is observed: dermatitis, tenosynovitis, bursitis, myositis. When the transition to a chronic stage in patients constantly occur inflammation of one or more joints. In the area of the affected joint, tofuks are deposited, as a result of the periarticular tissues thicken, the mobility in the joint is impaired. Tofuses 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. With ultrasound examination, they look like rounded or oval hypoechoic formations of various sizes in the thickness of the skin and subcutaneous tissue. In connection with osteolysis, a rough deformation of the joints is observed. Lesion of joints is asymmetric.