The causes of knee pain vary depending on the patient’s age and whether the knee is damaged or not. The symptoms also vary greatly as to the location of the pain and the physical posture that induces the pain depending on the specific cause. Knee pain often results from damage to the ligament, meniscus or cartilage, or due to degenerative arthritis, which is closely related to aging. Some patients complain of knee pain which has nothing to do with the knee structure as it can be caused by a herniated lumbar disc. In any case, it is very important to find the exact cause.
The location and characteristics of the pain and the postures that result in pain may vary depending on the cause. When there is a problem in the quadriceps femoris muscles or kneecap, the patient usually complains of pain in the anterior part of the knee, and when the pain is caused by degenerative arthritis or pes anserine bursitis, the patient often complains of pain on the medial side of the knee. Those who suffer from degenerative arthritis often comment “my knee aches when walking.” And in the case of meniscus damage, one usually feels pain when bending the knee or when.
Causes and symptoms of knee pain
For treatment of knee pain, there are a wide range of choices, from a simple change in everyday habits to a surgical operation. Therefore, the proper method of treatment should be decided in consideration of various factors such as the cause of the pain, its severity and the age of the patient. In the case of a simple fracture, the pain can be completely cured without any sequelae. But in the case of degenerative arthritis, a complete cure is difficult, so continuous management is more necessary.
Regarding pain control, people often wonder whether it is better to walk a lot or to move as little as possible. The answer naturally depends on the cause of the knee pain. In the case of degenerative arthritis, it is better to refrain from actions that can burden the cartilage of the knee, like walking up a steep incline or running. In contrast, walking on flat ground or in the water applies an appropriate amount of stimulation to the cartilage of the knee, and is thus strongly recommended.
As a knee joint supports one’s weight, weight control plays an important role in managing knee pain. There are many studies which indicate that when an overweight person (BMI 25 or above) complains of pain caused by degenerative arthritis, it helps a lot in reducing pain and recovering bodily functions if one can reduce one’s weight by 5 percent. On such occasions, reducing one’s weight is not usually sufficient since it is necessary at the same time to reinforce one’s muscular strength around the knee through adequate exercise.
To ameliorate knee pain, sometimes balneotherapy is recommended. According to certain studies, the warm water at hot springs helps relax stiff muscles and joints, thereby reducing pain and facilitating body movements through an increase in the range of joint movements. During the acute inflammatory phase of knee pain, it is necessary to reduce the load on the knee with the use of equipment such as a cane or walker, and during the chronic phase, this kind of equipment can enhance bodily functions when necessary. In the case of knee pads, they can be of help in protecting knee joint structures during the acute inflammatory phase, but wearing them for a long period can weaken the strength of muscles around the knee. Hence, it is better to ask for advice from a doctor who specializes in rehabilitation medicine or orthopedics.
Exercises for knee pain
One of the common questions that patients who suffer from chronic knee pain such as degenerative arthritis ask is what kind of exercise is most helpful for knee pain. There is no principle to determine what particular exercise is best, but a generally recommended one is low-impact aerobic exercise. Low-impact aerobic exercise, such as walking, swimming, bicycling or yoga, is a kind of rhythmic exercise that has a minor impact on the knee joints as one foot is always touching the ground. In contrast, the kind of high-impact exercises to be avoided include those in which both feet are off the ground at the same time, such as running and jumping, which have a more severe impact on knee joints.
There is no set principle as to how much exercise is most appropriate for knee pain as it all depends on the cause of the pain. However, in the case of degenerative arthritis and according to guidelines suggested by the U.S. National Academy of Sports Medicine in 2010, aerobic exercise is recommended for at least three days a week, muscle exercise for two or three days, and stretching for every day. When starting the exercise, it is better to begin with 5-10 minutes of aerobic exercise, which should be extended to 20-30 minutes per day or up to 150 minutes per week. All exercise programs should include at least one set of muscle-strengthening exercise, and when possible it would be better to repeat it 10-15 times.
As for aerobic exercise, such exercises as walking, bicycling and swimming are recommended, as mentioned above, and a certain amount of jogging is also beneficial. In a study that was carried out over 15 years, 866 patients with muscular-skeletal pain were divided into two groups, those who jogged every day and those who did not, for a comparative study. The results showed that jogging itself did not deteriorate the arthritic condition, and proper jogging significantly reduced the muscular-skeletal pain. However, it turned out that when knee pain had recently occurred or when the pain was relatively severe, jogging itself could be a burden for the knee joints, necessitating a consultation with a qualified doctor.
One effective exercise for knee pain patients is a muscle-strengthening exercise of the quadriceps femoris muscles. In this exercise, the patient lies down with a pillow under his or her knees and keeps the knee fully stretched for 10 seconds or leans on a wall with his or her knee bent 45 degrees for 10 seconds repeatedly, while taking care not to allow the knee to protrude ahead of his or her toes.
Quite a few patients are reluctant to do exercise because of the pain. In such cases, it is better to start exercising after the pain is relieved, usually by taking an anti-inflammatory painkiller for a week or starting it at a time during the day when pain is least troublesome. Exercising in water is another alternative, as pain is relieved due to the lessened load on knee joints.
But more than anything else, it is important to practice a warm-up exercise before starting the main program in order to avoid damaging the joints, or to practice a cool-down exercise for 5-10 minutes in order to prevent post-exercise pain. As shown through recent studies, groups that practiced a warm-up exercise using the quadriceps femoris muscles had a lower incidence of post-exercise pain compared to groups that did not.
As mentioned above, knee pain can be controlled to a satisfactory degree through careful management and steady exercise in everyday life. However, if the pain continues or gets more severe, it is important to consult a qualified doctor in a rehabilitation clinic or an orthopedic doctor in a nearby hospital as the causes of knee pain are quite diverse.
By Kim Sang-jun
The author is a doctor at Samsung Medical Center’s Department of Physical and Rehabilitation Medicine and a professor at the Sungkyunkwan University School of Medicine. ― Ed.