Knee Pain in the Elderly: Common symptoms, varied causes

Knee pain in the elderly is a very common occurrence. The knee is the largest and most complex joint in the body. Injuries and diseases of the knee are frequent sources of disability, pain, and lost days from work.  Discomfort may be associated with many different diseases. The pain can affect the ability to ambulate, participate in daily activities and sleep comfortably.    The causes of pain usually originate in the knee joint.  Occasionally, a problem elsewhere can trigger pain that is referred to the vicinity of the knee.  Problems that originate in the knee joint itself are generally easy to diagnose and can be treated by your primary care physician, rheumatologist, or orthopedic surgeon.  Referred pain to the knee usually comes from either the hip or the spine and can be more difficult to diagnose.

Statistically, Americans are nearly 100% likely to have an episode of knee pain at least once in their lifetime. The incidence of knee pain is higher with increasing age and therefore is very common in the elderly. Initial attacks of knee pain, may respond to home remedies such as the use of rest, ice or heat, anti-inflammatory medications, weight loss, and a low impact exercise program.  Knee pain that lasts more than 10 days and is associated with swelling in the joint or inability to weight bear generally requires a visit to your physician.  Physical exam x-rays and occasionally blood testing are included in the diagnostic evaluation. 

Common causes of knee pain

            Inside the knee joint

a.       Osteoarthritis

b.      A torn meniscus

c.       Rheumatoid or Inflammatory Arthritis

d.      Gout

e.       Knee joint infection

f.        Tendonitis or Bursitis

Outside of the knee joint

a.       Hip arthritis

b.      Sciatica

                       

Osteoarthritis (OA) is the most common cause of knee pain in the elderly.  OA is the wear and tear type of arthritis that we are all subject to.  The incidence is slightly higher in women than men.  Increasing rates of obesity and decreased rates of exercise have resulted in an epidemic of OA in our society.  Most patients experience a slow gradual increase in pain and swelling.  Physically, there is often a bow legged appearance especially with weight bearing.  Inside the knee, a patch like loss of covering cartilage on the end of the bones allows the bones to rub together. Commonly the arthritis is also associated with a longstanding meniscus tear.   Initial treatment consists of rest, ice, anti-inflammatory medicines, weight loss and a low impact exercise program.  Injectable lubricates are available for arthritic knees and can temporarily diminish symptoms in moderate cases.  Dietary supplements are commonly advocated (glucosamine and chondroitin) but have never been shown effective in scientific studies. For severe arthritis, knee replacement surgery has extremely high success and patient satisfaction rates.

The meniscus is a structure in the knee shaped much like a washer. It is rubbery in nature and acts to help increase the contact area between the thigh and shinbone as they meet in the joint. Twisting and squatting activities are known to facilitate tears of the meniscus and can be the inciting event to bring on pain. A torn meniscus or cartilage can occur at any age.  Although this condition is common in young athletes, it can occur in the elderly as well.  In the elderly, the tear usually occurs incrementally and gradually over a period of months or years.  As a result, the appearance of a problem can be sudden or insidious.  Most torn menisci are on the medial or inside joint line of the knee and are associated with swelling, intermittent locking, difficulty with squatting or rising from a chair. When the tear catches, the patient will have a snapping or a grinding sensation. This problem can turn on and off like a light switch. With large tears the ability to ambulate is limited. A physical exam can establish the diagnosis.  Initial treatment includes rest, ice, and anti-inflammatory medications.  A steroid injection into the joint may help dramatically. Occasionally arthroscopic surgery is necessary to resolve the symptoms.

Rheumatoid arthritis is less common overall than osteoarthritis and presents more in women by a ratio of 8 to 1. Rheumatoid arthritis is an autoimmune disease in which the immune system of the patient begins attacking the synovial lining and covering cartilage within the joint.  Hallmarks of the disease include: at least an hour of morning stiffness, rashes, symmetrical involvement, and joint deformity especially in the hands. The disease process eventually destroys the joint surface. Laboratory data frequently can confirm the presence of rheumatoid arthritis. Over the last decade the use of disease-modifying medications have become prevalent and for the first time in modern history, the disease can actually be slowed dramatically by the appropriate use of these medications. Generally after the diagnosis of rheumatoid arthritis is made the patient should come under the care of a family doctor or rheumatologist who can administer and monitor the use of these medications appropriately. If and when rheumatoid arthritis causes significant destruction of the cartilage covering the end of the bone, knee replacement surgery is an appropriate next step.

Gout is more common in elderly men.  It occurs in genetically sensitive patients when uric acid levels in their blood exceed the saturation point and they crystallize in synovial joints.  The crystals cause sudden intense pain, swelling and redness. The big toe knuckle is most commonly involved, followed by the ankle and the knee joint.  Attacks can be triggered by diet (foods high in urates), alcohol and aggravation.  Some diuretics are known to trigger an attack.  The diagnosis requires a reasonable suspicion and can be confirmed by the finding the presence of gout crystals in fluid from the knee joint.  An attack will subside rapidly after the administration of the right medications.  Prevention of further attacks is accomplished by diet, and prophylactic medicine.  Although infection of the knee joint is unusual, it closely mimics gout with the main difference being the presence of fever and malaise. Infection can occur after a penetrating injury, or in immuno-compromised patients. 

Tendonitis and bursitis of the knee are common in patients of all ages. They can occur as a result of injury, repetitive activities, arthritic conditions or even gout. Generally the location of the pain is specific to the presence of a tendon or a bursal sack and treatment is supportive with anti-inflammatory medications and rest. The conditions usually resolve promptly.

Osteoarthritis(OA) of the hip joint can cause pain radiating to the knee. Patients sometimes arrive convinced that the knee is the source of the problem, only to find out that x-rays of the knee are normal and x-rays of the hip on the same side show severe arthritis. Generally the type of limp caused by a bad hip has a characteristic John Wayne waddle while the knee limp is more stiff-legged.

Sciatic pain emanating from the low back commonly results in pain radiating across the knee. Nerves exit the spine and coalesce into the sciatic nerve. Pressure on these nerves from arthritis or disk problems can produce pain down the back of the leg and the posterior aspect of the knee.  Cramping, spasms, and numbness often accompany pain from sciatica. 

Summary

There are many causes of knee pain in the elderly; most conditions are not serious and can be treated using anti-inflammatory medications, rest, ice, and activity modification. If the symptoms don’t resolve over 10 days to 2 weeks a visit to your doctor is advised.  A diagnosis will likely be made quickly and appropriate treatment begun.  Longstanding and increasing knee pain in the elderly is most likely arthritis related.  Arthritis is the loss of the cartilage covering on the end of the bones that meet in the knee joint.  If this becomes severe, and medication, physical therapy, exercise and weight loss do not resolve the problem, knee replacement surgery results in extremely high success and satisfaction rates in appropriately selected patients.