Causes

The ankle joint is a commonly injured joint in the body. While ankle fractures and ankle sprains heal pretty well, they can lead to problems much later in life. This is due to the wear and tear that occurs for years after the injury. This condition is called osteoarthritis, or post-traumatic arthritis. The term trauma means injury, and the term post-traumatic arthritis is used to describe the condition of the arthritis after injury.

Degeneration is a term that describes a condition where something wears out over time. The term degenerative arthritis is used by doctors to describe a condition where a joint wears out, usually slowly over a period of many years. The term arthritis means inflammation of a joint, so the term degenerative arthritis means inflammation of a joint due to wear and tear. You may also hear the term degenerative arthrosis used. Some doctors believe that degenerative arthritis isn't a true arthritis and confuses people. The term arthrosis is used to describe the condition of a worn out joint. The term arthritis is used to describe the true inflammatory conditions such as gout, infection and rheumatoid arthritis.

Osteoarthritis is usually considered a type of degenerative arthritis, or wear and tear arthritis. Doctors usually consider osteoarthritis pretty much the same whether it appears years after an injury to the joint or whether it simply appears without any history of injury. Over the past several years, there has been increasing evidence that osteoarthritis is genetic, meaning that it runs in families. Research suggests that osteoarthritis that occurs without any injury may be related to differences in the chemical makeup of the articular cartilage with which people are born.

Injury to a joint, such as a bad sprain or fracture, can cause actual damage to the articular cartilage. The cartilage can be damaged by bruising when too much pressure is exerted on the cartilage surface of a joint. This damages the cartilage, although if you look at the surface it may not appear to be any different. The injury to the material doesn't show up until months later. Sometimes the cartilage surface is damaged even more severely and pieces of the cartilage are ripped from the bone.

These pieces do not heal back and usually must be removed from the joint surgically. If not, they may float around in the joint causing the joint to catch and be painful. These fragments of cartilage may also do more damage to the joint surface. The areas where these pieces of cartilage are ripped from do not normally grow back. Unlike bone, the holes in the surface are not simply replaced by the cartilage tissue around the hole. Instead the defects are filled with scar tissue. The scar tissue that forms is not nearly as good a material for covering joint surfaces as the cartilage it replaces. It just can't support weight bearing like true articular cartilage.

An injury to a joint, even if it does not injure the articular cartilage directly, can alter how the joint works. This is true for a fracture where the bone fragments heal slightly different from the way they were before the break occured. It is also true that when ligaments are damaged it leads to instability in the joint. When an injury results in a change in the way the joint moves, the injury may increase the forces on the articular cartilage. This is very similar to any mechanical device or machinery. If the mechanism is out of balance, it wears out faster.

Over many years this imbalance in the joint mechanics can lead to damage to the articular surface. Since articular cartilage cannot heal itself very well, the damage adds up. Finally, the joint is no longer able to compensate for the increasing damage and it begins to hurt. The damage is occurring well before the pain begins.

Degenerative arthritis may come from differences in how each of us is put together based on our genes; a condition best described as osteoarthritis. Or degenerative arthritis may come years after an injury has occured that leads to slow damage to the joint surfaces; a condition probably best described as post- traumatic arthritis. Either way the joint is worn out - and it hurts.

Symptoms

Pain is the main problem with osteoarthritis of any joint. At first, the ankle joint pain occurs only related to activity. Once the activity gets underway there is not usually much pain, but after resting for several minutes the ankle pain and stiffness increase. Later, when the condition worsens, pain may be present even at rest. The pain may interfere with sleep. There may be a swelling around the ankle joint and it may fill with fluid and feel tight, especially following increased activity. When all the articular cartilage is worn off the joint surface there may be a squeaking sound when the ankle joint moves. Doctors refer to this sound as crepitance. Osteoarthritis will eventually affect the motion of the ankle joint and it will become stiff and lose the ability to move.

Certain motions can become painful, and it may become difficult to trust the ankle joint to hold your weight in certain positions. The body has a pain reflex to ensure that, when a joint is put into a position that causes pain, the muscles around the joint may stop working without warning. This reflex can lead to falls when arthritis affects the leg joints. When osteoarthritis has reached a very severe stage, the bone under the articular cartilage may become worn away. This can lead to increasing deformities around the ankle joint. In the final stages, the alignment of the joints can begin to form odd angles where they meet to form the joint.