Overweight and obese people must be most concerned with osteoarthritis, or degenerative joint disease, of the knee. It is described as a wearing away of the cartilage that cushions and protects bone surfaces in a joint. In the obese person, the wearing down of the cartilage in the knee is hastened by the sheer bulk the knees must support.
There are several Predisposing factors, or those factors which increase your chances of developing osteoarthritis in the knee. However, one of the most commonly seen predisposing factors is obesity. Obesity affects the knee in the following manner: the knee is the largest joint in the body. It not only bends and straightens, but it also has some rotational motion. While walking at a normal pace, the knee must bear three to five times our body weight. When we climb stairs or run, the force it must bear increases to seven or eight times our body weight. Normally, all of the components of the knee work in harmony, and we are pain free. However, when the knee is overstressed due to the excessive weight which is placed upon it by the obese person, the soft tissue structures around and within the knee joint become over-stressed. This will result in:
• the soft tissue structures, especially the ligaments which support the knee and keep it straight will begin to stretch and tear. This causes the knee to become unstable, weak, and painful.
• the cartilage which protects the ends of the bones within the knee joint will wear down pre-maturely and unevenly. When this occurs two things happen:
- bone will rub against bone, causing stiffness, immobility, and intense pain.
- the cartilage within the knee is our body's main shock absorber. As this cartilage wears down pre-maturely and unevenly, it cannot protect the body from the shock that occurs with each step we take. The results are: pain, stiffness, and osteoarthritis of the knee, hip and lower back. If these problems are not immediately addressed, and the knee protected, the affected structures will gradually break down, causing complete immobility of the knee.
The other predisposing factors which will increase a person's chances of developing osteoarthritis of the knee include the following conditions. If these conditions exist in an obese person, then the chances of knee pain and arthritis occurring is truly great:
• Pronation is a turning out of the foot at the ankle, so that one has a tendency to walk on the inner border of the foot. When the foot turns out, the lower leg and knee are forced to turn inward (internal rotation). This causes extra pressure to be exerted on the inner knee cartilage, which in turn produces a pre-mature and uneven wearing down of this portion of the knee's cartilage. The result is inflammation, stiffness, pain, and eventually osteoarthritis. Custom-made foot orthotics are needed to control pronation in order to straighten out the lower leg, and to insure an even pressure across the knee's cartilage. Custom-made orthotics will help to prevent: uneven wear and tear on the knee's cartilage, and osteoarthritis. Custom-made orthotics, along with preventive bracing, is discussed in a following section, Self-Treatment.
• Heredity: bow legs, one leg shorter than the other, and flat arches are other commonly seen biomechanical disorders that can cause pre-mature and uneven wearing down of the knee cartilage. These biomechanical disorders prevent the lower leg from being straight, so that the lower leg applies uneven pressure across the knee joint (cartilage). This uneven pressure causes pre-mature and uneven wearing down of the knee cartilage.
• Aging: the normal wear and tear that our joints undergo during our lifetime. The saying is true: "If you live long enough, you will develop osteoarthritis."
• Trauma: it may be due to an injury of a joint. This injury can be due to over-utilization of the joint, a fracture, or surgery on a joint.
The most common symptoms that one may experience are:
1. Brief period of morning stiffness that lessens after moving around.
2. Aching pain in the knee which increases with use, and is relieved by rest.
3. The affected joint usually appears swollen, and this swelling feels "hard." However, there is no redness, nor increased warmth around the joint.
4. The affected joint is tender when you apply pressure to it.
5. The range of motion of the joint is usually limited.
6. In the later stages of osteoarthritis of the knee, a grinding or "clicking" sound or feeling may occur when the joint is moved.
Self-Treatment of the Knee Joint in the Obese Individual:
The most successful treatment is to protect the knee joint, especially when we are weight-bearing. This is the "Gold-Standard" of medical treatment, the treatment most recognized by all of medicine to be effective. Protecting the joint will ensure:
a. a reduction in joint pain
b. significant slow down in the progress of the disease
c. a reduction in the chances of our injuring other joints when we walk. If we have a painful knee, we sub-consciously force ourselves to walk in an abnormal way, so as to try and minimize the pressure we exert on the knee joint. When we do this, we apply abnormal and excessive pressure on other parts of our body (such as the hip, back, etc.). This is called compensation. Compensation leads to over-utilization of these areas, and new sites of pain, swelling, and eventually osteoarthritis.
The two most effective treatments used by doctors and therapists to protect the arthritic knee joint are:
1. Knee braces that provide pain relief by:
• Stabilizing the knee.
• Exerting mild and soothing compression to reduce swelling of the knee.
• Providing support for the knee ligaments and tendons that have been affected by arthritis. When the knee joint wears down unevenly, some of the ligaments and tendons around the knee are stretched. Unless supported by a knee brace, these stretched ligaments and tendons will cause pain.
2. Custom-made orthotics that help protect the knee from the ill effects of obesity and arthritis: Our custom-made orthotics stabilize the knee by overcoming the abnormal forces that are exerted on the knee by bow-legs, a short leg, pronation, and flat arches. When stabilized, the lower leg sits straight within the knee joint, and this prevents an uneven and painful wearing down of the knee cartilage.
Our custom-made orthotics are made with space-age shock absorbent materials that absorb the shock of each step, rather than passing the shock on to the knees. This will give general shock absorbing protection to the hip and lower back, making each step a joy! For more information about our custom-made orthotics for arthritis of the knee, click here.