The course of an arthrosis usually extends over many years. The patient is usually not aware of the beginning of the disease. Only when the arthrosis has progressed do symptoms appear.
The starting point of any arthrosis is damage to the cartilage coating, the so-called “cartilage damage“. This damage is often initially limited to a small area. It is also still superficial.
Shortly afterwards, the first densifications of the bone appear in the X-ray image. These are always bone areas that lie directly under the diseased cartilage. These additional changes in the bone are a decisive sign for the early stage of arthrosis.
Without these bone changes, there is only “cartilage damage”, but not “arthrosis”. Arthrosis therefore always means cartilage damage with bone changes. There can be many years between the course of the arthrosis from the “early stage” to the “late stage”.
Many arthrosis patients are therefore in a so-called intermediate stage. Their changes are therefore more pronounced than in the early stage, but even less than in the late stage. In this stage, activated arthrosis can also occur, which can accelerate the wear and tear of the joint.
In the late stage, the articular cartilage in the diseased area is not only diseased and damaged, but even completely abraded and disappeared. As a result, the now exposed bone rubs directly against the bone on the opposite side of the joint. The X-ray image shows that the bones of the joint partners are in direct contact with each other. The so-called joint gap has therefore disappeared. The bone has also changed compared to the early stage.
Typical changes in the X-ray image in osteoarthritis
The soft tissues (muscles, tendons, ligaments, etc.) in the vicinity of the joint are also affected by the consequences of arthrosis. By sparing the painful joint, the muscles become weaker and less flexible.
Depending on the change in the shape of the joint, certain ligament structures shorten, while others are overstretched. This results in instability of the joint. The general risk of accidents increases.
The arthrosis continues to increase. The joint capsule becomes rigid and the range of motion for the joint decreases. Synovial hernias or cysts (e.g. Baker’s cyst of the knee joint) can form as a result of fluid formation in the joint mucosa (synovia).
By sparing the affected joint, incorrect posture and incorrect loading of other joints can occur. This makes it clear that osteoarthritis is not a disease that is restricted to the affected joint alone. – Narrowing of the joint space as an indication of a reduction in cartilage thickness
- Change in the bone beneath the cartilage damage; it becomes denser and therefore more visible on X-ray (sclerosis (white)).
- Bone attachments; the joint reacts to the damage with an increase in surface area, so-called osteophytes. The affected person notices that his or her joints are larger and distended. These bone spikes can also touch each other during certain movements and cause further pain. – Formation of cysts; cysts (fluid-filled cavities) often form near the arthrosis
- Change in shape; the joint loses its original shape, the joint loses its congruence, it becomes “crooked”.
