Joints are composed of several parts and different structures. When the joint is affected by osteoarthritis, all of these parts and structures may be affected in varying degrees. This accounts for the many changes that occur in osteoarthritic joints. By knowing these changes, you can better understand the measures taken by your doctor.

Joints Have Many Functions

  • Our joints enable us to move. We carry out  many thousands of movements every day,  usually without consciously being aware of  them. The joints are naturally lubricated to improve and facilitate these movements. The lubricant consists of a fluid film that is secreted by the mucous membranes lining the interior of the joints.

  • Joints have a shock absorber to cushion sudden, hard movements: the joint cartilage. This smooth, resilient coating protects the joints during movements and allows movements to progress in a normal pattern.

  • Joints provide stability. Joints have important structures that guide certain movements and prohibit others. For example, the joint in the fingertip can move only like a hinge. It does not permit side-to-side movements. The joint is protected against “wrong” movements. This protection is provided by portions of the joint capsule (called the“fibrouscapsule”) and the ligaments that “bind” the joint together.
  • Early Stage

Osteoarthritis always starts with damage to the cartilage that covers the joint surfaces. At first, this cartilage damage is often limited to a small area of perhaps half a square inch. Also, the damage is still superficial.

Within a short time, x-rays of the joint show an increase in the density of the bone. This always occurs in bone areas that are located directly beneath the diseased cartilage. These additional changes in the bone area are critical signs that early osteoarthritis has developed. Without the changes to the bone, there is only “cartilage damage”, but no “osteoarthritis”. Therefore, osteoarthritis always means cartilage damage in addition with changes to the bone.

  • Late Stage

Many years may lie between the “early stage” and the “late stage”. Therefore, many osteoarthritis patients find themselves in an intermediate stage that lies somewhere in between. Their changes are more pronounced than in the early stage, but still less than in the late stage.

In the late stage, the joint cartilage in the diseased area is not only diseased and damaged, but completely eroded and worn away. This causes the now unprotected bone to rub directly on the opposing bone. This is also called “bone-to-bone contact”. On the x-ray you can see that the bones directly touch each other. The so-called joint space has therefore disappeared in this area.

The bone itself has also changed in relation to the  early stage:

  • It is substantially denser and harder and is prominently recognizable on x-rays.
  • The joints have developed large bony jagged edges. These bony outgrowths (“osteophytes”) cause the joint to broaden. The patient notices that the affected joints are larger and expanded. These bony spurs can also touch each other during certain movements and cause additional pain.

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