Excessive impact, joint injuries and age are all factors that contribute to osteoarthritis of the knee.
While there is not much one can do about some of those things, the most important thing that can be done to improve this degenerative condition of the joint is to shed excess body weight, said DrCindy Lin, a staff-attending physician at the Changi Sports Medicine Centre at Changi General Hospital.
For each excess kilogram of body weight, three times that amount of pressure is exerted on the knee joints.
That means someone who is overweight by 10kg is putting 30kg of stress on his knees, said DrLin.
Losing weight through diet or exercise is one of the best things one can do either to prevent knee osteoarthritis completely or from getting worse.
Knee osteoarthritis can also be caused by malalignment of the knee joint, heavy manual labour with repetitive squatting, kneeling, or carrying heavy loads, or a previous traumatic injury to the knees such as meniscal tears or injury that required surgery, said Dr Lin.
In osteoarthritis, the cartilage between the two bones that meet at the knee gets worn down. As the condition progresses, the underlying bone may also degenerate.
People who do sports such as weight lifting and soccer have been found to be associated with a higher likelihood of developing knee osteoarthritis later in life.
Contrary to popular belief, however, running does not cause or exacerbate osteoarthritis of the knee. And runners who do develop osteoarthritis due to other causes can probably continue running if they take care of the symptoms, which include pain, stiffness, swelling and progressive deformity.
Studies do not point to an increased rate of osteoarthritis for the distances that most recreational runners train at, said Dr Jason Chia, head of Sports Medicine & Surgery Clinic at Tan Tock Seng Hospital.
Some studies have put recreational running distances at between 12 and 42km a week.
Studies of veteran runners also do not show that they get osteoarthritis in the knee that is more severe than for the general population, said Dr Chia.
Unfortunately, knee osteoarthritis can be so painful that some people stop running or doing any exercise altogether.
But stopping all exercise may actually do more harm than good to one's overall health.
The lack of exercise and, hence, use of the joints will lead to loss of strength and joint stability, and result in even more pain and disability.
Doctors and physiotherapists here say exercise can help to improve joint strength and flexibility.
So staying active, even with knee osteoarthritis, should result in less knee pain and disability over time, even though the person may feel some temporary discomfort when starting a new exercise programme.
It is especially beneficial to engage in regular exercise that strengthens the hip and thigh muscles above the knees so they help take the load off the knee. If runners are careful to lay off training when symptoms are acute, then running is possible when there is no pain, swelling, inflammation or deformity.
Every person will have to judge how much he can do given the severity of his condition.
"Ultimately, as the degeneration progresses, it is probably prudent to switch to lower impact activities," said Dr Chia.
After an episode of acute symptoms, it is important to rehabilitate the knee to restore flexibility and strength. One should not just depend on the absence of pain as an indication that it is all right to return to running, said Dr Chia.
Mr Ray Loh, an exercise physiologist at the Sports Medicine & Surgery Clinic at Tan Tock Seng Hospital, said research shows that muscle weakness and atrophy are commonly associated with osteoarthritis of the knee.
"Nowadays, strengthening exercises have become one of the components of the management guidelines," he said.
Here, he shows five strengthening exercises that concentrate on the lower part of the body, which are suitable for preventing knee osteoarthritis as well as to rehabilitate the knee.
Add the following exercises to your general strengthening routine two or three times a week.