You wake up in the morning and your knees ache before you ever get out of bed. You open a can of soup and a shaft of pain shoots through your elbow. You pick up a half-gallon of milk and suddenly realize you're not sure you can hang on to it. Welcome to old age?

No, say the experts. All that aching, stiffness, swelling and weakness is disease, not aging. It is not normal and it shouldn't be written off as something you have to live with.

"Pain is never normal; it's real important to understand that," according to Dr. Rose Maly, an assistant professor of family medicine at UCLA who specializes in geriatrics. "If pain persists, if it's severe, if it localizes in one specific area or is combined with a rash, fatigue or prolonged morning stiffness, it needs to be looked at."

The most common cause of joint pain in older people is osteoarthritis, a degenerative joint disease in which the cartilage deteriorates, leaving bone rubbing on bone. If you live long enough, chances are you'll get a chance to experience it firsthand.

"Most osteoarthritis is caused by a previous injury to the joints, although there is a certain amount of heredity," said Dr. Thomas LaGrelius, a geriatrics specialist with a private practice in Torrance. "The cartilage surface of a joint is very delicate and once there's a nick in it, that spot is eventually going to fray and wear through.

"Since most of us end up getting nicks — we don't want to live in a box; we want to get out and ski or rollerblade or play tennis — 20 or 30 years down the road we're going to have problems," explained the Southern California physician.

Those problems can range from mild discomfort, to joints that become painfully enlarged and knobby. It's osteoarthritis — or its companion, rheumatoid arthritis — that most people mean when they talk about arthritis and rheumatism, neither of which is an actual medical condition, according to the American Medical Association's Family Medical Guide.

Rheumatoid arthritis is a chronic disease in which the immune system attacks the synovium, a thin membrane surrounding joints, causing them to become swollen, inflamed and stiff. It generally affects the small bones of the hands and feet and frequently is accompanied or preceded by feelings of listlessness, weight loss, muscular pain and a low-grade fever.

Rheumatoid arthritis is primarily a disease of the young, with only 10 percent of those over 60 developing it. Gout, bursitis, tendinitis, polymalgia rheumatica and low thyroid levels are other diseases and conditions that can cause what most people frequently think of as "growing old" pains. Knowing when to go to get those pains checked out, especially when they come and go, can be difficult.

"If there's a reasonable explanation for the joint pain — you just twisted your ankle going down the street — then you can ignore it for a while," LaGrelius said. "But any joint pain that involves multiple joint or muscle pain that persists for more than a few weeks or is accompanied by general illness should be looked into."

That's important because joint pain can mask more serious diseases such as malignancies, an aneurysm of the aorta, infection in the bone, or inflammatory bowel disease.

"There are a number of possibilities besides joint problems," said Maly, "but it's not just a matter of ruling out tumors and dire possibilities. There's a lot we can do to help people with joint-related diseases to function better and to improve their quality of life, even if the condition itself is not curable.

"Non-steroidal anti-inflammatory drugs like aspirin, acetomenophen and ibuprofen can help, so can injecting the joints with cortisone." Rehabilitation, physical therapy, occupational therapy and even surgery can also help, she said.

Joint replacement surgery shouldn't be regarded as a last resort, Maly stressed.

"You don't have to hobble around in terrible pain. Some joint replacement surgeries, especially hip replacements, are extremely successful and can completely eliminate pain."

Theoretically, almost any joint can be replaced — fingers, wrists, ankles, shoulders, elbows — although the neck, axial spine and very tiny joints are hard to do. Most prosthetic joints are made of metal or a combination of metal and plastic or porcelain. Replacement surgery can run from $20,000 and up.

"Patients are usually in the hospital a week or so and then a rehabilitation facility for a week or two for physical therapy," LaGrelius said. "Then they require a couple of months using a walker to protect the joint while the cement cures."

By far the vast majority of joint-related conditions can be managed with medication, using anti-inflammatory drugs and pain relievers.

"If you're only talking about pain, most of the over-the-counter drugs are equally good," says LaGrelius. "A couple Tylenol, aspirin or Advil every four hours should do the trick."

One major exception is gout: Aspirin can slow the excretion of excessive uric acid, which causes the disease in the first place.

"If you're trying to stop an inflammatory reaction, then Tylenol won't work at all, nor will low doses of aspirin or Advil," LaGrelius said. "In the case of aspirin, it would take 16 to 18 tablets a day and that wouldn't be safe without close medical supervision.

"These drugs are potentially toxic and can cause ulcers, kidney failure and liver toxicity," he continued. "Even moderate doses of Tylenol taken over years and years can cause kidney damage."

Two developments may offer new hope to osteoarthritis sufferers, although both are in the preliminary stages.

"There's some early evidence that vitamin D intake…may actually slow down or prevent future cartilage deterioration," said Maly. She cautioned, however, that the findings are "very preliminary."

The other new kid on the block is cartilage implants. "They're playing around with replacing cartilage inside joints," LaGrelius said. "The idea is if you have a chunk out of the cartilage you could pack it with cells and have it regrow. Whether that's going to become practical and feasible is somewhat debatable."

When the aches and pains begin, how do you know just what's ailing you and whether to tough it out or seek medical help? Here's a rundown of some of the more common joint-related conditions and diseases, many of which show up as people enter their 50s and 60s.

*Osteoarthritis is a degenerative joint condition in which the cartilage surface of the joint wears thin, allowing bone to rub against bone, causing pain. It is most apparent in the larger, weight-bearing joints — including the hips, knees and spine of older people.

*Rheumatoid arthritis is a chronic inflammatory joint disease in which the immune system identifies joint-lining as foreign tissue and attacks it. The disease is most common in 20- to 40-year-olds and occurs most often in the small joints of the hands and feet.

*Bursitis involves an irritation of the bursa, the soft sac that minimizes friction between moving body parts such as tendons and bones. Bursa are almost always located over some bony point like the tip of an elbow, knee or shoulder. When irritated by pressure or injury to the nearby joint, the sac can become inflamed and distended with fluid.

*Tendinitis — a tearing and inflammation of the tendon (the tissue that connects muscles to bones) — results in swelling, tenderness and pain. The pain generally disappears after a few weeks or months, but can become worse, especially in older people. Tendinitis can occur anywhere, but is most common at the shoulders or heels, on the outside of the elbow (tennis elbow) or the inside (golfer's elbow).

*Gout is a disease in which excess uric acid accumulates, forming crystals that can become lodged within the joint. The crystal inflame the surrounding tissue and irritate the nerve endings, causing extreme pain.

*Polymalgia rheumatica, a disease common among older people, results in acute illness, as well as soreness and weakness of the muscles of the shoulders and hips. People with polymalgia rheumatic typically have trouble getting in and out of chairs.

*Low thyroid levels is a condition common to the elderly. It results in stiffness and sore joints. The condition is frequently overlooked and should be screened for by blood work. It can be easily alleviated by increasing the patient's thyroid level.