What is the cause of suprapatellar bursa swelling?

In the early stage, rheumatoid arthritis lacks specific X-ray diagnostic features. However, if we combine various symptoms and signs, common parts, laboratory examination and X-ray examination results, we can make a quite reliable diagnosis. If we can see the joint destruction and typical deformities with the characteristics of this disease in the later stage, such as some typical deformities of fingers and wrists, we can make a reliable diagnosis. X-ray examination of the affected joints of this disease is not only for the diagnosis, but also for providing objective and reliable indicators for staging, selecting treatment methods and continuing to observe the progress of the disease.

(1) General X-ray examination results:

① Soft tissue swelling: Soft tissue swelling of the affected joint is often caused by synovial hyperplasia and joint cavity effusion, so it is more common in the early and middle stages of arthritis. This soft tissue swelling centers on the joint and spreads around the joint, pushing the fat layer, muscle or subcutaneous tissue with more X-rays outward. The swelling of soft tissue confined to one side of the joint may be an image of subcutaneous nodules. Of course, the quality of X-ray photos is very important for carefully observing the swelling of soft tissues. In this disease, soft tissue calcification is generally invisible.

② Osteoporosis: Osteoporosis caused by the disease is universal, because the disease has a long course and involves many joints. If the patient stays in bed, sees little or no sunlight, and has poor nutrition, the whole body osteoporosis may reach a very serious degree, so that the loose bones are charcoal-shaped (only the outline of the bone cortex can not be seen). Osteoporosis is often more serious in patients who use adrenocortical hormone for a long time, which not only causes carbon-like phalanges and metacarpals, but also causes pathological compression fractures of most vertebral bodies.

③ Changes of joint space: Joint space stenosis is very common. In osteoarthrosis, it may only cause partial stenosis of joint space, while rheumatoid disease often causes all stenosis of joint space. The reason of joint space stenosis is the atrophy, thinning or destruction of articular cartilage surface, which is often caused by the direct corrosion of pannus of cartilage surface and the release of various proteases by neutrophils, which can dissolve collagen fibers and hyaluronic acid in cartilage matrix, make cartilage lose its supporting substances in the matrix, and lead to cartilage atrophy, thinning and finally disappear. Enlargement of joint space in rheumatoid arthritis is not common, but occasionally seen in the early stage of the disease.

④ Bone changes: In addition to the aforementioned osteoporosis, other bone changes can also be seen. Bone erosion at the edge of cartilage surface and cystic degeneration of subchondral bone are quite common in middle and late stage lesions, which is the result of erosion of rheumatoid granuloma (pannus). The formation of periosteal new bones is more common in the small bones of hands and feet of young patients, such as metacarpal bones, phalanges, phalanges and FDA3? Bone, phalanx and distal radioulna are common; Bone resorption at the bone end after joint destruction can be seen in the facet joints of hands and feet and acromioclavicular joints. It is worth noting that phalangeal resorption is a characteristic of psoriatic arthritis and systemic sclerosis, and it does not exist in this disease. Bone compression deformation can be seen in pelvis and vertebral body with high osteoporosis. The former can be triangular and acetabular invagination, while the latter can form most pathological compression fractures.

⑤ Joint dislocation and deformity: Severe joint injury and muscle spasm are the causes of joint dislocation and subluxation, such as wrist joint drooping deformity, knee flexion contracture deformity, metacarpophalangeal joint ulnar deviation deformity, finger gooseneck deformity, buttonhole deformity and forefoot deformity. FDA5？ Eversion and claw toe deformity, etc.

⑥ Stiffness of joint: After the articular cartilage surface is completely destroyed and disappeared, fibrous and bony fusion occurs in the joint, which makes the joint stiff. Some irregular joint spaces can still be seen in the former, while the latter disappears completely and trabecular bone passes through. Stiffness rarely occurs in functional positions, but often occurs in various abnormal positions.

(2) X-ray staging of rheumatoid arthritis:

According to the staging standard of American Rheumatology Association, the X-ray manifestations of rheumatoid arthritis in China are divided into four stages.

Early stage (osteoporosis): extensive osteoporosis and swelling of soft tissue.

Mid-stage (destruction stage): In addition to early detection, there are bone end edge corrosion, subchondral cystic degeneration and joint space stenosis.

Advanced stage (severe destruction stage): In addition to the above findings, there are serious joint destruction, bone resorption, dislocation and deformity.

End stage (ankylosing stage): the joints have been fibrous or bony ankylosing.

This stage mainly depends on the degree of joint damage shown on the X-ray film, rather than the length of the disease. In addition, the disease stages of each affected joint in the same patient are different, some may still be in the middle stage, and some may have reached the late stage or terminal stage.

(3) X-ray manifestations of different joints:

① Finger arthritis: Osteoporosis and spindle swelling of joint soft tissue can be seen in the early stage. Swelling is often symmetrical, mostly in the proximal interphalangeal joint, and less in the distal interphalangeal joint. Occasionally, reactive new bone formation of phalangeal periosteum can be seen. Later, the joint space narrowed, the bone edge was corroded or subchondral bone cystic degeneration was seen. Serious joint injury, metacarpophalangeal joint dislocation, flexion deformity, ulnar deviation deformity, finger buttonhole deformity, gooseneck deformity and so on may occur in the later stage. On the other hand, sometimes we can see different degrees and types of malformations. Later, you can see joint stiffness, but this is rare.

② Wrist arthritis: Osteoporosis and carpal soft tissue swelling can be seen in the early stage, and the swelling is more common on the back of wrist joint and near ulna. Later, the carpus appeared moth-eaten corrosion, the joint space between the carpus was narrow, the joint space between the lower ulna and the radius was widened, and occasionally reactive new bone was formed in the periosteum of the lower ulna. Later, it can be seen that the destruction of the wrist joint is further aggravated, the ulna is dislocated backward, the wrist joint is deformed due to palm flexion and ulnar deviation, and finally the bone of the wrist joint is ossified.

③ Elbow joint: X-ray features of elbow joint are few. Early decalcification, osteoporosis and soft tissue swelling can be seen. In the later stage, the joint space is narrow and the edge of the bone is corroded. In the late stage, due to bone destruction and absorption, the olecranon notch of ulna is enlarged, and bone hyperplasia can be seen in the medial humerus-ulnar joint and coronal process. Later, the common joint osteoporosis, elbow flexion stiffness.

④ Shoulder arthritis: Extensive osteoporosis and joint effusion can be seen in the early stage, and soft tissue swelling can be seen. Bone erosion at the edge of humeral head can be seen in the back. It is rare that the shoulder joint is severely damaged and leads to dislocation or stiffness.

⑤ Hip arthritis: Hip involvement is often bilateral. In the early stage, osteoporosis and soft tissue swelling were the main causes. The pelvis, acetabulum and greater trochanter are all osteoporosis. The obturator foramen of the affected side becomes smaller. Due to the swelling of synovium in the joint, the fat layer outside the joint capsule is pushed outward and swollen. In the later stage, bone erosion at the edge of femoral head, subchondral bone cystic degeneration and joint space stenosis can be seen. Osteoproliferative changes can be seen in the late stage, mainly at the outer edge of acetabulum and the lateral edge of femoral head. Patients with long course of disease or long-term use of adrenocortical hormone have acetabular invagination because the pelvis is too soft. Femoral head resorption or joint stiffness and dislocation are rare.

⑥ Knee arthritis: Osteoporosis and soft tissue swelling can be seen in the early stage. On the lateral X-ray film, the suprapatellar bursa is located behind the quadriceps femoris tendon and above the patella (the normal suprapatellar bursa cannot be seen on the X-ray film, and the rectangular soft tissue shadow can only be seen when the suprapatellar bursa is swollen or hydrops). The swelling of the infrapatellar fat pad can also be clearly seen on the lateral radiograph. In the later stage, erosion of bone end edge, subchondral cystic change and narrowing of joint space can be seen. The joint injury in the late stage is serious, which can produce genu varum, genu valgus and flexion contracture deformity. Severe flexion deformity often leads to posterior subluxation of the upper tibia. Osteoankylosis is rare.

⑦ Ankylosing arthritis: Osteoporosis and soft tissue swelling are the main symptoms in the early stage. On the positive X-ray film, soft tissue swelling around the medial malleolus and lateral malleolus can be seen. On the lateral X-ray film, the fat layer outside the anterior ankle joint capsule swelled outward, and the swelling ankle joint capsule squeezed behind narrowed the shadow of the triangular transparent area in front of the achilles tendon. Severe joint injury and foot drop deformity can be seen in the late stage. Stiff joints are rare.

⑧ Foot arthritis: Osteoporosis and swelling of soft tissue on the dorsum of the foot can be seen in the early stage of arthritis in the posterior part of the foot, and the gap between talocalcaneal joint, talocalcaneal joint and cuboid joint becomes narrower, the edge is corroded and talocalcaneal window disappears in the later stage. Osteoankylosis is rare. In the early stage of forefoot arthritis, toe thickening and osteoporosis can be seen, and occasionally new bone formation of toe periosteum can be seen. Later, it can be seen that the joint space is narrowed and the edge is corroded. See you later. FDA5？ Hallux valgus, flatfoot and claw toe deformity, and skeletal rigidity are rare.

These are the most common X-ray manifestations of rheumatoid diseases involving joints. In fact, rheumatoid arthritis can involve all synovial joints, which is not discussed here.