Arthritis For Dummies. Barry Fox

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Chapter 2

      Osteoarthritis: The Most Common Form

      IN THIS CHAPTER

      Whether you call it osteoarthritis, degenerative arthritis, or degenerative joint disease, osteoarthritis (OA) is the painful result of cartilage breakdown. When the tough, rubbery substance that cushions bone ends no longer does its job, the bone ends can’t slide easily across each other within the joint. That’s when pain and stiffness can settle into a joint. Suddenly, your knee or lower back aches, your hip burns, a finger joint swells and throbs, or your shoulder stiffens up. You can’t bend and flex the painful joint like you used to; its range of movement is limited. Most of all, it just plain hurts!

      But what happened to mess up your cartilage in the first place? To understand what went wrong, here’s a look at how things work in healthy cartilage.

Considering Cartilage

      Healthy cartilage is absolutely essential for joints to function properly and painlessly. Slick as polished marble and tough as galvanized rubber, cartilage protects the ends of your bones from wearing each other away where they meet inside a joint. It also provides a smooth, slick surface so bone ends can glide easily across each other. And cartilage is an excellent shock absorber, cushioning the bones and soaking up the impact created by movement and physical stresses. Without intact cartilage, bones grind away at each other and bear the brunt of the impact of movement. Eventually, the joint itself can be damaged or even destroyed.

      Four elements help cartilage do its all-important job:

      Water, collagen, proteoglycans, and chondrocytes all work together to keep your joints moving like well-oiled machinery. When the pressure is released from a joint, say your knee when you lift your leg to take a step, water rushes into the cartilage, nourishing, bathing, and plumping it up. The water-loving proteoglycans, woven securely into the collagen web, soak up water and hold on to it until pressure is applied to the joint (that is, you take another step). Then the water and wastes rush out of the cartilage. But as soon as the pressure is off, the proteoglycans thirstily soak up the water again. The resilient collagen stretches and shrinks to accommodate joint pressure and water content, so your cartilage can bounce back after being flattened out.

But if your cartilage loses its ability to attract and hold water, it becomes thin, dry, cracked, and unable to provide a slippery surface (see Figure 2-1). No longer plump and resilient, it makes a poor shock absorber and cushion for the bones, particularly affecting the weight-bearing joints.

      © John Wiley & Sons, Inc.

      FIGURE 2-1: Osteoarthritic joints have narrowed joint space, and thin, rough, broken-down, or completely missing cartilage.

You can visualize the action of the cartilage by thinking of two cans of soup facing each other end-to-end with an almost-filled water balloon in between them. As you press the soup cans together, the water balloon changes shape to accommodate the pressure, but never lets the cans actually touch. When you release the pressure, the water balloon (like your cartilage) resumes its old shape.

Identifying the Signs and Symptoms of Osteoarthritis

Don’t assume that you have osteoarthritis just because you have one or more of the following symptoms. Get a thorough examination and diagnosis from a qualified physician. Figure 2-2 shows you the most common sites affected by osteoarthritis.

      How do you know if the joint pain you’re suffering from is due to osteoarthritis? Most of those with the disease have at least one of the following symptoms:

       Joint pain: Most people experience joint pain as a deep-seated ache radiating from the inner core of the joint. The feeling is distinctly different from a muscular ache and may come СКАЧАТЬ