What is arthrosis?
Joints consist of several parts with various structures. If a patient suffers from arthrosis, all parts and structures of the joint can be affected to varying degrees. This is the reason for the numerous changes that can be observed in an arthrotic joint. Being familiar with them helps to understand the medical measures.
Our joints perform numerous tasks:
Our joints allow us to move. Every day, we perform thousands of movements, most of them without being aware of them. These movements are enhanced and facilitated by the synovial fluid which is produced by the inner synovial membrane.
Joints have shock absorbers to absorb sudden and hard movements, i.e. the joint cartilage. This smooth and elastic coating protects the joint during movement and allows for a proper motion sequence.
Joints provide support and have important structures that guide certain movements while preventing others. For example, a finger end joint can only be moved like a hinge, but does not be open laterally. The joint is protected against wrong movements. This protection is provided by parts of the joint capsule (so-called fibrous capsule) and the ligaments.
What are the various stages of arthrosis and how can this joint disease be defined?
The early stage of arthrosis is a damage of the cartilage coating, i.e. a cartilage defect. Often this defect is limited to a small area of e.g. two square centimetres. At this stage, the defect is only superficial.
Shortly afterwards, initial bone density changes can be observed on radiographs. Only areas directly underneath the diseased cartilage are affected. These bone changes are a clear indicator for the early stage of arthrosis. Without them the patient only suffers from a cartilage defect, but not from arthrosis. Thus, arthrosis is always defined as a cartilage defect with bone changes.
Between the early and late stage of arthrosis many years can pass. Many patients are at an intermediate stage between the early and late stage. Thus, bony changes are more severe than in the early stage, but less severe than in the late stage.
During the late stage, the joint cartilage in the affected area is not only damaged, but completely torn and missing. The exposed bone directly rubs on the bone on the other side which can be seen on the radiograph. Both bones are in contact. The so-called joint space is no longer visible and bone changes have occurred as compared to the early stage:
It is much denser and harder and more visible on the radiograph.
At the joint margins large bony edges have developed. These bony prominences (osteophytes) lead to a widening of the joint. The patients notices a clear enlargement and swelling of his joints. These osteophytes can even touch during certain movements and cause further pain.
Causes and consequences of arthrosis
As mentioned above, the causes of arthrosis first lead to a cartilage defect. Hundreds or even thousands of different factors can lead to a cartilage defect. Accidents, overloading, congenital joint deformities, metabolic disorders and probably even poor nutrition are the major causes.
Patients are all too familiar with the consequences of arthrosis:
Thickening and deformation
Every joint and stage has various degrees of severity.