it’s going to rain.”) The pain typically increases as the joint is used and eases off with joint rest. As the disease worsens, though, the pain can become fairly steady. If joint pain occurs during the night, poor sleep and next-day fatigue may be two unpleasant side effects.© John Wiley & Sons, Inc.FIGURE 2-2: The neck, lower back, knees, hips, ends of the fingers, and the base of the thumbs are the sites most commonly affected by osteoarthritis.Some people really can feel it in their joints when it’s going to rain, because as the barometric pressure falls, the lining of an arthritic joint can become inflamed, causing pain and the release of excess fluid (swelling).
Stiffness and loss of movement: Stiff joints, limited range of motion, and, in later stages, joints that freeze into a bent position are all signs of osteoarthritis.
Tenderness, warmth, and swelling around the joint: Although swelling is not usually a big problem with osteoarthritis, some joints do swell in response to cartilage damage and irritation, especially if they’ve been overused. The finger joints and the knees are most often affected.
“Cracking” joints: If you hear popping or crunching sounds when you move a joint, you may have osteoarthritis. These cracking sounds (doctors call them crepitus) can be created by roughened cartilage. (This isn’t the same thing as “cracking” your joints by applying pressure to them, which causes a harmless release of nitrogen bubbles and isn’t associated with OA.)
Bony growths on the fingers: Bony lumps, either at the ends of the fingers (called Heberden’s nodes) or on the middle joint of the fingers (called Bouchard’s nodes) are signs of osteoarthritis. These types of bony growths may be hereditary.
Discovering What Causes Cartilage Breakdown
Sometimes, we really don’t know why the cartilage disintegrates. In that case, we designate the problem as primary osteoarthritis, or osteoarthritis of unknown cause. Other times we know that the osteoarthritis has been triggered by another problem, in which case we call it secondary osteoarthritis.
Considering causes of primary osteoarthritis
The ultimate cause of primary osteoarthritis remains a mystery. Although scientists aren’t sure why, the collagen mesh of the cartilage becomes scrambled; it weakens and can’t hold its structure. The proteoglycans, once so cozily intertwined in the collagen mesh, suddenly find themselves evicted from their secure homes. As they float off into the joint fluid, they take their water-retaining abilities with them. The cartilage is left high and dry; it thins and may even crack. At the same time, the newly freed proteoglycans draw excess fluid into the joint capsule, causing swelling. (Unfortunately, this fluid can’t get back into the cartilage, where it’s desperately needed. It’s something like dying of thirst in the middle of the ocean.)
Although no one is absolutely certain what causes primary osteoarthritis, here are a few theories:
The chondrocytes become too efficient at breaking down the collagen and proteoglycan molecules. In healthy cartilage, the amount of breaking down enzymes is equal to the amount of building up enzymes. An overabundance of destructive enzymes leads to weakened collagen and a lack of proteoglycans.
The chondrocytes go wild and start making too many proteoglycan and collagen molecules. The opposite of the previous condition, these chondrocytes are too good at making new cartilage components. The excess proteoglycan and collagen molecules, in turn, pull extra fluid into the joint, flooding it and washing away most of the chondrocytes. The cartilage, then, is left bereft of cartilage-producing molecules.
Sorting out the sources of secondary osteoarthritis
Although the origins of primary osteoarthritis remain murky, experts are quite sure what causes secondary osteoarthritis: various types of trauma to the joints or an autoimmune arthritis (like RA or gout). That includes sudden, high-velocity trauma (the kind you’d experience in a car accident), as well as little insults to your joints that occur time and again, like repeated poor posture or running on a concrete surface every day for years. The causes of secondary osteoarthritis can be further broken down as follows:
Joint injury: Weekend warriors beware! Once a joint has been injured, be it through a sports mishap, car accident, household slippage, or anything else, it is much more likely to develop osteoarthritis.
Repetitive motion injury: Joints that are stressed over and over again in the same way (for example, a ballerina’s ankles, a football player’s knees, or a data processor’s wrists) are more likely to experience a cartilage breakdown than joints subjected to normal use.
Damage to the bone end: Usually due to trauma or continual stress, a bone may chip or sustain small fractures. In the body’s zeal to repair the damage, it may cause an overgrowth of bone in the injured area. The result is a bone end that’s bumpy, not smooth, and joint problems can ensue.
Bone disease: A bone disease, such as Paget’s disease, weakens the bone structure, making it more likely to fracture and develop bony overgrowth.
Carrying too much body weight: The heavier you are, the more stress your knees, hips, and ankles must bear. Osteoarthritis of the knee has been clearly linked to excess body weight. That’s not surprising considering that every time you take a step the stress on your knee is roughly equivalent to three times your body weight. Increase that figure to ten times your body weight when you run!
Regarding the repair problem
To make matters worse, once your cartilage is damaged, your body can compound the problem if it repairs itself in certain ways. Like injured bone, injured cartilage can overdo the repair process, piling too much new cartilage into a crack or tear. The result is a lumpy, bumpy surface that doesn’t glide smoothly against the cartilage on the opposing bone end. On the other hand, sometimes the cartilage doesn’t repair itself at all, and remains in its damaged state — cracked, pitted, frayed, and even worn-through. Pieces of loose cartilage and/or bone may break off and float freely through the joint fluid. The bone ends, no longer well cushioned, start to rub against each other and can develop bony spurs (osteophytes) that further interfere with smooth joint movement. The joint space narrows, and the entire shape of the joint can change. All this from a little damaged cartilage!
Recognizing Risk Factors for Osteoarthritis
Although osteoarthritis affects more than 30 million Americans, not everybody suffers from it. Some people actually sail into their golden years with joints unaffected by pain, stiffness, or other symptoms, while others are hobbling around by the time they’re 35. So how come one person gets osteoarthritis while another gets away scot-free? And how can you tell if you happen to be particularly susceptible to it?
Your chances of developing osteoarthritis are increased if:
You’re past
