Common Knee Injuries
There are many diseases and injuries that can occur at the knee. Below are a summary of the most common ones.
Arthritis
There are some 100 different forms of arthritis, rheumatic diseases, and related conditions. Virtually all of them have the potential to affect the knees in some way; however, the following are the most common.
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Osteoarthritis. Some people with knee problems have a form of arthritis called osteoarthritis. In this disease, the cartilage gradually wears away and changes occur in the adjacent bone. Osteoarthritis may be caused by joint injury or being overweight. It is associated with aging and most typically begins in people age 50 or older. A young person who develops osteoarthritis typically has had an injury to the knee or may have an inherited form of the disease.
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Rheumatoid arthritis. Rheumatoid arthritis, which generally affects people at a younger age than does osteoarthritis, is an autoimmune disease. This means it occurs as a result of the immune system attacking components of the body. In rheumatoid arthritis, the primary site of the immune system’s attack is the synovium, the membrane that lines the joint. This attack causes inflammation of the joint. It can lead to destruction of the cartilage and bone and, in some cases, muscles, tendons, and ligaments as well.
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Other rheumatic diseases. These include:
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Gout. An acute and intensely painful form of arthritis that occurs when crystals of the bodily waste product uric acid are deposited in the joints.
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Systemic lupus erythematosus (lupus). An autoimmune disease characterized by destructive inflammation of the skin, internal organs, and other body systems, as well as the joints.
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Ankylosing spondylitis. An inflammatory form of arthritis that primarily affects the spine, leading to stiffening and in some cases fusing into a stooped position.
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Psoriatic arthritis. A condition in which inflamed joints produce symptoms of arthritis for patients who have or will develop psoriasis.
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Reactive arthritis. A term describing forms of arthritis that are caused by infectious agents, such as bacteria or viruses. Prompt medical attention is essential to treat the infection and minimize damage to joints, particularly if fever is present.
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SYMPTOMS
Symptoms vary for each form of arthritis. For example, people with rheumatoid arthritis, gout, or other inflammatory conditions may find the knee swollen, red, and even hot to the touch.
Any form of arthritis can cause the knee to be painful and stiff.
DIAGNOSIS
The doctor may confirm the diagnosis by conducting a careful history and physical examination. Blood tests may be helpful for diagnosing rheumatoid arthritis, but other tests may also be needed. Analyzing fluid from the knee joint, for instance, may help diagnose gout. X rays may be taken to determine loss or damage to cartilage or bone.
TREATMENT
Treatment is dependent on the type of knee arthritis.
For osteoarthritis, care focuses on symptom relief with pain reducers (aspirin, acetaminophen), NSAIDs (like ibuprofen), or occasionally corticosteroid injections.
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Inflammatory conditions such as rheumatoid, ankylosing spondylitis, or psoriatic arthritis often require DMARDs or biologics when NSAIDs or injections are insufficient.
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For all types of arthritis, strengthening exercises and weight loss can help reduce joint stress.
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When arthritis causes severe damage or persistent, disabling pain, surgery—typically total knee replacement or, more recently, arthroscopic procedures—may be considered.
Meniscal Injury
The menisci can be easily injured by the force of rotating the knee while bearing weight. A partial or total tear may occur when a person quickly twists or rotates the upper leg while the foot stays still (for example, when dribbling a basketball around an opponent or turning to hit a tennis ball). If the tear is tiny, the meniscus stays connected to the front and back of the knee; if the tear is large, the meniscus may be left hanging by a thread of cartilage. The seriousness of a tear depends on its location and extent.
SYMPTOMS
Generally, when people injure a meniscus, they feel some pain, particularly when the knee is straightened. If the pain is mild, the person may continue moving. Severe pain may occur if a fragment of the meniscus catches between the femur and the tibia. Swelling may occur soon after injury if there is damage to blood vessels. Swelling may also occur several hours later if there is inflammation of the joint lining (synovium). Sometimes, an injury that occurred in the past but was not treated becomes painful months or years later, particularly if the knee is injured a second time. After any injury, the knee may click, lock, feel weak, or give way. Although symptoms of meniscal injury may disappear on their own, they frequently persist or return and require treatment.
DIAGNOSIS
In addition to listening to your description of the onset of pain and swelling, the doctor may perform a physical examination and request x rays or an ultrasound of the knee. An MRI may be recommended to confirm the diagnosis.
Occasionally, the doctor may use arthroscopy to help diagnose a meniscal tear.
TREATMENT
If the tear is minor and the pain and other symptoms go away, the doctor may recommend a muscle-strengthening program. The following exercises are designed to build up the quadriceps and hamstring muscles and increase flexibility and strength after injury to the meniscus:
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Warming up the joint by riding a stationary bicycle, then straightening and raising the leg (but not straightening it too much).
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Extending the leg while sitting (a weight may be worn on the ankle for this exercise).
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Raising the leg while lying on the stomach.
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Exercising in a pool (walking as fast as possible in chest-deep water, performing small flutter kicks while holding onto the side of the pool, and raising each leg to 90 degrees in chest-deep water while pressing the back against the side of the pool).
Before beginning any type of exercise program, consult your doctor or physical therapist to learn which exercises are appropriate for you and how to do them correctly, because doing the wrong exercise or exercising improperly can cause problems. A health care professional can also advise you on how to warm up safely and when to avoid exercising a joint affected by arthritis. If your lifestyle is limited by the symptoms or the problem, surgery may be indicated.
Chondromalacia
Chondromalacia (KON-dro-mah-LAY-she-ah), also called chondromalacia patellae, refers to softening and breakdown of the articular cartilage of the kneecap. This disorder occurs most often in young adults and can be caused by injury, overuse, misalignment of the patella, or muscle weakness. Instead of gliding smoothly across the lower end of the thigh bone, the kneecap rubs against it, thereby roughening the cartilage underneath the kneecap. The damage may range from a slightly abnormal surface of the cartilage to a surface that has been worn away to the bone. Chondromalacia related to injury occurs when a blow to the kneecap tears off either a small piece of cartilage or a large fragment containing a piece of bone (osteochondral fracture).
SYMPTOMS
The most frequent symptom of chondromalacia is a dull pain around or under the kneecap that worsens when walking down stairs or hills. A person may also feel pain when climbing stairs or when the knee bears weight as it straightens. The disorder is common in runners and is also seen in skiers, cyclists, and soccer players.
DIAGNOSIS
Your description of symptoms and an x-ray or MRI usually help the doctor make a diagnosis. Although arthroscopy can confirm the diagnosis, it’s not performed unless conservative treatment has failed.
TREATMENT
Many doctors recommend that people with chondromalacia perform low-impact exercises that strengthen muscles, particularly muscles of the inner part of the quadriceps, without injuring joints. Swimming, riding a stationary bicycle, and using a cross-country ski machine are examples of good exercises for this condition. If these treatments don’t improve the condition, surgery may be indicated.