Joint diseases in cats will slowly break out as they age. The causes of joint diseases are divided into congenital and acquired causes. Specific diagnosis requires some auxiliary means such as X-ray examination to confirm the diagnosis. In the case of joint diseases, In radiographic examination, different symptoms have different appearances, which require us to identify them.

1. Changes in joint surfaces

The articular surface is not smooth. The articular cartilage and the underlying bony articular surface bone are eroded and replaced by pathological tissue, causing the joint to be destroyed and the articular surface to be uneven. In the early stage of the disease, when only articular cartilage is destroyed, the joint space becomes narrowed, and the bony articular surface is damaged and appears nibbled, rough, or with obvious defects. It is more common in the late stages of septic joint inflammation, degenerative joint disease, etc.

When the articular margin ossifies, new bone proliferates around the articular surface, forming an articular lip or articular osteophyte. It is more common in degenerative osteoarthropathy and ossification of tendons and ligaments. A round or round-like defect area shadow appears in the articular subchondral bone in the joint bone cyst cavity. The shadow has clear edges and may or may not communicate with the joint cavity. This is called a bone cyst.

The joint surface is broken, cracks appear on the joint surface or there is a large defect in the joint bone. Seen in intra-articular fractures or bone end fractures.

2. Changes in joint space

Joint space widening. Due to inflammation, a large amount of joint effusion is caused. The joint capsule can be bulged and the joint space is widened. Such lesions are more common in various effusion arthritis and arthropathy.

Joint space narrowing When joints undergo degenerative changes, articular cartilage degeneration, necrosis, and dissolution cause joint space narrowing, which is more common in the later stages of septic arthritis, degenerative joint disease, etc.

Uneven width of the joint space. When the supporting ligaments of the joint, such as the collateral ligaments, are broken, the joint loses stability. At this time, the joint will show an X-ray image with one side wide and one side narrow.

The disappearance of joint space is mostly an X-ray manifestation of bony connection of the joint, that is, bony ankylosis of the joint. When the joint is obviously destroyed, the bone ends of the joint are connected by bone tissue, resulting in bony healing. It is more common in post-healing acute septic arthritis and degenerative joint diseases.

The result of intra-articular fracture with foreign body in the joint space is that the fracture fragments are free in the joint cavity, and a high-density bone image appears; during joint penetration, foreign bodies can enter the joint cavity, and the shadow of the foreign body can be seen; after the joint is infected with gas-producing bacteria, the An air shadow appears in the joint space.

3. Changes in extra-articular soft tissue shadows

The main cause of swelling is inflammation of the joints. Due to joint effusion or congestion, hemorrhage, edema and inflammatory exudation of the joint capsule and its surrounding soft tissues, the soft tissues around the joints are swollen. X-ray films show increased shadows, increased density and unclear tissue structure of the extra-articular soft tissues.

Atrophy, jointsExternal soft tissue atrophy can cause the shadow and density of extra-articular soft tissue to shrink on X-ray films. Such lesions are common in joint disuse, such as long-term fracture fixation.

Open injury to a joint occurs when a foreign body in the soft tissue enters the soft tissue, and an air shadow or shadow of the foreign body appears in the shadow of the soft tissue outside the joint. Avulsion fractures of joint capsules or joint ligaments and ossification of muscles, tendons, ligaments or joint capsules at the joint bone insertion points will cause high-density bony shadows to appear in the extra-articular soft tissue shadows.