The Arthritis Handbook
Improve Your Health and Manage the Pain of Osteoarthritis
By Grant Cooper DiaMedica PUBLISHING Copyright © 2008 Diamed, LLC
All right reserved. ISBN: 978-0-9793564-1-4
Understanding Your Joints
The joints of the human body truly are remarkable. Without them, we could not sit, stand, run or jump, play Chopin's "Minute Waltz," throw or catch a winning touchdown pass, shake hands, dance the tango, type on a keyboard, or raft down the Colorado River. Each joint in the body delicately balances stability and flexibility, depending on its function. This same delicate balance is also why we suffer when our joints develop a disease such as arthritis and become painful or stiff.
A joint is a location at which two bones make contact and move in relationship to each other; this is called an articulation. Most people have 206 bones and 143 joints. Having so many joints provides a lot of flexibility, but each joint is also a potential site of problems such as pain, stiffness, and inflammation. Depending on the joint, it may be fixed, slightly flexible, or more flexible. The skull, for example, is made up of several bones that are joined together by fixed joints. The sacroiliac joints that connect our spine to our hips are slightly flexible. Other slightly flexible joints include the joints between the vertebrae in our spine. By contrast, our hips, shoulders, knees, and finger joints are examples of flexible joints. As a general rule, the more flexible a joint is, and the more weight-bearing responsibility that it has (think of the hip or knee), the more likely that particular joint is to develop arthritis.
There are many different types of flexible joints. For example, the shoulder and hip joints are examples of ball-and-socket joints, the most flexible type of joint in the body. If your shoulder weren't so flexible, you would find it very hard to position your hand where you wanted to in space. The price for this flexibility is that these joints are more likely to dislocate than those that are less flexible.
The knee and elbow are examples of hinge joints, which function in a way similar to the opening and closing of a car door. The thumbs have saddle joints that allow you to pick things up. Your ankles and wrists have gliding joints that allow the bones to glide smoothly over each other. The pivot joints in your neck allow for side-to-side movement-you can thank your pivot joints for your ability to give a disapproving headshake whenever you want to!
Each mobile joint in your body has the same basic structure (Figure 1.1). The joint capsule is on the outside; it is made of tough fibrous tissue that adds strength and stability to the joint and connects the articulating bones. A sheet of synovium lines the capsule; its cells secrete synovial fluid. This fluid, along with water, is the chief constituent of the fluid within the joint. Synovial fluid is thick, straw-colored, and found in small amounts in the joint. The thickness is due in large part to an important component called hyaluronic acid. Keep these two words in mind, because injecting hyaluronic acid into the knees and other joints (such as the hips and shoulders) can alleviate symptoms in some people with arthritis. Another important substance inside the joint is called cartilage.
Joints need cartilage to function properly. Up to eight times more slippery than ice, and with the ability to soak up and push out water as easily as a sponge, cartilage is perfectly designed to permit seamless motion between bones, while at the same time providing ideal shock-absorbing capacity. In the world of joints, cartilage is a true superhero. Scientists have put men on the moon, eradicated polio, made flying an everyday event, and decoded DNA, but they haven't yet been able to create a substance that is better suited for joints than the body's own healthy cartilage.
Cartilage is made of collagen, proteoglycans (core proteins that are attached to carbohydrate chains), chondrocytes (cells that make cartilage), and up to 80 percent water. When you are at rest and your joints are not bearing weight, cartilage stores synovial fluid and water within it. When a joint is loaded with a force, the fluid stored in the cartilage is redistributed to the joint. In other words, when you stand from a seated position, the weight you put on your knee pushes the synovial fluid and water out of the cartilage in your knee, much as it would push the water out of a wet sponge inside your knee. The fluid pushed into the joint space helps to cushion your weight and also nourishes the joint. It moves back into the cartilage when you sit down.
In addition to this sponge-like property, cartilage has another cushioning advantage-it is filled with negatively charged chondroitin molecules. Negative particles resist touching each other with astounding atomic force. When the joint is made to bear weight, these chondroitin molecules are pushed together, but their negative charges resist. Pushing two negatively charged chondroitin molecules together is like trying to force two negatively charged magnets together. The closer they come to touching, the stronger they repel each other.
In osteoarthritis, cartilage degenerates, losing its cushioning and smooth, lubricating effects. As the amount of cartilage decreases, increasing stress is placed on other structures within the joint, such as the bones, joint capsule, ligaments, and tendons.
Mobile Joint Anatomy-A Brief Review
* A tough, fibrous joint capsule on the outside of the joint connects the bones.
* Synovium lines the joint capsule and secretes synovial fluid.
* Synovial fluid lubricates the joint and nourishes the cartilage.
* Cartilage allows for seamless motion between bones and provides shock-absorption.
The Supporting Structures of Bone
Joints don't work in a vacuum. In order to function properly, they require muscles, tendons, ligaments, and bursae. Let's explore the different parts of the body that interact intimately with the joints:
* Muscles provide the force needed to torque, flex, and extend joints.
* Tendons are tough bands of tissue that attach muscles to bones.
* Ligaments are tough, fibrous bands of tissue that attach bone to bone. In addition to tendons, ligaments cross the joints and help provide stability.
* Bursae are small, fluid-filled sacs that are strategically scattered throughout the body-there are about 160 of them. They contain the same synovial fluid as in joints; they provide cushioning over the bones, ligaments, and muscles. The bursae provide this cushioning in much the same way as bubble wrap provides protection for packages.
When joints are working well, they are one of life's many marvels. All the components of the joint and its supporting structures-bones, ligaments, muscles, tendons, cartilage, bursae, and synovial fluid-work in unison to bring about the intricate movements of a ballerina performing a pirouette as well as the more mundane yet critical functions we all do, including brushing our teeth. However, like many brilliant facts of life, we often take the proper functioning of our joints for granted. We use and abuse them, and only seem to notice them at all when they hurt or become stiff.
Our joints are so important that, when they become diseased and start to lose their normal function, they affect our lives in a profoundly negative way. Any component in a joint can malfunction and cause pain and stiffness. The real problem is that once one part of the joint starts to break down, others tend to follow until a vicious cycle develops. For example, if a ligament is injured, the surrounding muscles have to compensate for the injury. The muscle opposite the injured ligament may have to contract more strongly to take pressure off of the injured side. This increased exertion by the muscle may pull one of the bones slightly to the side, forcing the edges of the two bones to scrape together. This scraping causes inflammation that spreads to the synovium, and so forth. This cycle of destruction leads us to the first two rules of arthritis management:
Rule #1: The sooner arthritis is diagnosed and treatment is started, the better.
Rule #2: Once symptoms begin, the entire joint, including the surrounding structures, must be treated, including but not limited to the underlying injury.
Consider Rule #1
Arthritis is a progressive condition when left untreated. If treatment is begun early in the process, you can avoid further degeneration and the need for more aggressive treatments such as drugs and surgery.
Consider Rule #2
You've had arthritis in your knee for years, but only recently did it start giving you real trouble. During the past few weeks, your knee hurt whenever you climbed even a few stairs or sat for too long. You went to your doctor, who told you what you already knew: your arthritis is acting up. The treatment consists of a steroid injection into your knee.
A steroid is a potent anti-inflammatory medication, and a steroid injection is similar to turning a fire hose on full blast to put out a small fire. The fire goes out, and you feel much better over the next few days and weeks. However, if you don't also address the underlying cause of your arthritis, the symptoms will return. In addition, when the symptoms recur, the underlying damage to the joint will have progressed, and the pain may be worse than before. Because the arthritis has progressed, a steroid injection may not work as well the second or third time. Thus, the entire joint and its surrounding structures must be treated so the symptoms will go away and stay away.
The Synovial Fluid
Synovial fluid is necessary for normal joint function. As discussed previously, synovial fluid moves into the cartilage when a joint is resting, and moves out into the joint space when the joint is active, particularly when the joint is engaged in a weight-bearing activity such as exercise. Synovial fluid lubricates the joints and permits smooth movement. It also provides important nutrients to them.
Joints are not vascularized, meaning that they have no direct blood supply. They get banged around a lot; bleeding could occur inside a joint every time it was injured if blood flowed through it. Even if blood had a quick escape route from the joints (which it does not), tough, fibrous scar tissue would develop and impair future functioning. Instead, the joint capsule receives limited blood by diffusion, which allows nutrients and waste products to be exchanged within the synovial fluid inside the joint.
If we don't use our joints, however, the synovial fluid remains within the cartilage and cannot interact with the joint capsule. Until the joints are stressed with movement and weight, their needs will be not be met. This brings us to the third rule of arthritis management:
Rule #3: Joints require movement to maintain optimal health and function.
The Benefits of the Third Rule
Following the third rule of arthritis management will help ensure that the joint receives adequate nutrients and that waste products will be removed. It will also help ensure that the muscles and other supporting structures around the joint are exercised and strengthened. When muscles around a joint are strong, they take some of the pressure off the joint. When muscles are weak, the static joint must bear the increased pressure.
Having agreed that arthritis is a joint problem that may include pain, stiffness, and inflammation, having discussed what a joint is, and having introduced the first three rules of arthritis management, we are now ready to discuss how arthritis develops.
Chapter Two How Joints Develop Arthritis
Cartilage degeneration is the primary underlying problem in arthritis. As discussed in Chapter 1, the smoothness of the cartilage allows for easy gliding between joints. Its sponginess allows synovial fluid and water to enter it during times of rest and rapidly exit when the joint is stressed by walking or other activity. The movement of these fluids provides the shock-absorbing capacity of the joint as well as the nourishment it needs.
There are two basic types of osteoarthritis: primary and secondary.
In secondary arthritis, something identifiable triggers the degradation of the cartilage. In other words, the arthritis follows the injury. This type of arthritis is seen in people who have suffered a severe trauma or repetitive microtrauma to a joint. They may be obese or overexert themselves (such as running a marathon without proper training). They may have abnormal body biomechanics, a term that refers to how the skeletal structures, including the bones, muscles, tendons, ligaments, and joints, function together-meaning how they move through space under the influence of gravity.
People with a history of severe joint trauma, such as a broken bone or a torn knee ligament, may have suffered cartilage damage at the time of injury. This damage initiates a process of degeneration that can cause further cartilage damage and erosion. People who suffer repetitive microtrauma, such as a runner who wears improper footwear, may experience continual microtrauma to the joint cartilage.
Once cartilage in the joint has been damaged, the cells that make the cartilage (chondrocytes) fill the small or large cracks created by trauma with new cartilage. Unfortunately, this new tissue is inferior to normal cartilage, and it is more likely to crack and overgrow into places where it's not needed, interfering with normal functioning. This sets the stage for further abnormal joint biomechanics.
Whenever the biomechanics of a joint are abnormal, increased stress is placed on parts of the joint that are not designed to deal with it, including bones, ligaments, and the joint capsule. More bone is added in response to these stresses for protection and cushioning. Bone is far from inanimate or static; quite the contrary, it is very much alive and dynamic. Bones are constantly breaking down and being rebuilt. When they are forced to take on the shock-absorbing role of cartilage, they create new bone in an effort to strengthen the joint. These extra pieces of bone are called bone spurs. They can rub against the surrounding muscles, tendons, ligaments, and synovium, causing irritation and inflammation. As the joint becomes inflamed and painful, you are more likely to avoid using it, leading to greater stiffness, a loss of critical nutrients, and atrophy of the surrounding muscles.
The muscles that surround joints are responsible for taking some of the load off them, particularly the weight-bearing joints. Atrophy and weakness of these muscles means they can no longer buffer the joint, which then has to carry an increased load. This leads to further breakdown, which leads to further pain, which leads to further disuse and more atrophy. Thankfully, strengthening the surrounding muscles can have a profound impact in taking the extra load off the joints, thereby reducing the downward spiral.
Obesity and overexertion can cause repetitive trauma to the cartilage. In overexertion, the surrounding muscles become fatigued, and the joints are forced to face increased loads. Joints are designed to accommodate temporary increases in load but-despite their elegant design, they do have limits. Lifting too much weight while squatting, jumping onto a very hard surface, or other sudden increases in load on a joint can lead to cartilage injury. As with other injuries, once the cartilage is damaged, it is more likely to suffer subsequent damage.
When the body functions optimally, weight is distributed so that weak structures bear less weight and stronger structures bear more. The biomechanics of the body are incredibly complex and, at the same time, sublimely simple. They are complex because of all the factors involved: the movement of the joints-the muscles pushing and pulling, the ligaments stretching and straining, and all the different angles and forces. They are simple because the body is designed to function logically and smoothly.
Understanding the core concept of body biomechanics is to understand that all the parts of the body are connected, and that a force directed at one part affects the rest. When you take a step, the impact of the force on your heel as it strikes the ground is transmitted up your leg to your knee. If your knee does not cushion and absorb the force, it will be redistributed to your hip. If your hip does not cushion and absorb the force, it will travel across your pelvis, and so forth.
Excerpted from The Arthritis Handbook by Grant Cooper Copyright © 2008 by Diamed, LLC. Excerpted by permission.
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