1. Not all arthritis is created equalIn my years in practice as a rheumatologist, I have noted that among patients and the medical community alike, there are some major misconceptions about arthritis.
The most common misconception may have come from the slogan “Arthritis: there is no cure.” Many equate the slogan to “Arthritis: there is no treatment.” Time and again, I have seen patients who have been told, “It’s arthritis and nothing can be done, so go home and live with it.”
The most dangerous misconception is that arthritis is not a serious disease. In fact, arthritis is the number one cause of disability in North America and affects people of all ages: it is not only a disease of the old.
It is also not true that all arthritis is the same: there are approximately 100 forms of arthritis. The most common form is osteoarthritis, which affects approximately 55 percent of us by age 65. Rheumatoid arthritis is less common, but does affect approximately 1 percent of the population; most of these people begin to be affected between the ages of 30 and 50.
What Is Arthritis?
Arthritis is derived from the Greek arthron (joint) and itis (inflammation). Therefore, arthritis by this definition would mean inflammation within a joint.
A joint is the structure that connects two bones. The joint is held together by ligaments and tendons and a capsule. The ends of the bones are covered with cartilage and the capsule is lined by a synovial membrane (see illustration below).
Cartilage is the white glistening stuff you have probably seen at the end of a chicken bone. It allows bones to glide smoothly over each other, with synovial fluid acting as a lubricant, and also absorbs the forces that impact on the joints. Cartilage is made up of collagen (protein fibres), water, chondrocyctes (the cartilage cells), and proteoglycans. Normal cartilage is essential to a well-functioning joint.
In arthritis, the cartilage may have become damaged. It may have thinned and eventually disappeared, leading to bone rubbing on bone. The damage to cartilage can occur in different ways, and this is why we have different forms of arthritis. The two major types of arthritis are degenerative (wear and tear) and inflammatory.
Degenerative arthritis is known as osteoarthritis. In this form of arthritis, the primary problem occurs in the cartilage. The cartilage may be damaged by a previous injury to the joint, or by a chronic stress on the joint (as in osteoarthritis in the knees of obese females). The cartilage itself may be abnormal because of a genetic defect that can lead to premature osteoarthritis in whole families. Degenerative arthritis used to be referred to as “non-inflammatory arthritis,” however, researchers have become increasingly aware that inflammation is an important factor in the progression of osteoarthritis.
In inflammatory arthritis, the inflammation in the joint causes the damage. The signs of inflammation are redness, heat, swelling, and pain. In the joint, this leads to loss of function. An example of an inflammatory arthritis is rheumatoid arthritis, in which the immune system is overactive, leading to inflammation mainly (but not always) in the synovium and the joint fluid. The inflammation itself causes pain and a poorly functioning joint, but ultimately, the cartilage is damaged and the joint is finished. Rheumatologists want to treat the inflammation before this happens.
Other conditions such as bursitis or tendonitis are not arthritis. They do not occur in the joint. They are referred to as soft tissue rheumatism, and are discussed in Chapter 2, “Not All Musculoskeletal Pain Is Arthritis.”
Osteoarthritis
Osteoarthritis is a common disease characterized by pain in the joint, stiffness, and loss of movement. It is also referred to as degenerative joint disease and osteoarthrosis. It is a slowly evolving disease that is part of the aging process. Autopsy studies have shown that by age 40, 90 percent of all persons have changes in the weight bearing joints (knees, hips) although, of course, all of these people did not have symptoms. By age 65, approximately 60 percent of us will have symptoms of osteoarthritis.
Not only is osteoarthritis common, but it has been around for a long time: dinosaur bones and Egyptian mummies all show evidence of osteoarthritis. Yet we still understand very little about this disease and specific treatment has eluded us.
Osteoarthritis is classified as a non-inflammatory arthritis. This implies that there is no inflammation, but recent research shows that this is not true. The factors that cause the disease (which starts in the cartilage) are not completely known. It is known that early on, although there is no inflammation yet, the cartilage starts to wear away and fragment, and the bone under the cartilage thickens. Loose pieces of cartilage cause an immune response and inflammation, which is known to be responsible for some of the progression of the disease. As the disease evolves, the cartilage thins and disappears. As well, new bone is formed at the joint edges (this is referred to as an osteophyte) and the bone under the cartilage continues to thicken.
Dr. Stein discusses in detail some of the causes of osteoarthritis in Appendix I, “Heredity and Environment,” but we will summarize some of the causes here:
· Trauma may lead to osteoarthritis (whether this is sudden, severe trauma, or a repetitive strain such as seen in obese females and osteoarthritis of the knees).
· The tendency to develop osteoarthritis can also be passed from parent to child in the genes, as we see with congenital hip dysplasia or erosive osteoarthritis of the hands (which seems to be passed from mother to daughter most commonly).
Classification of Osteoarthritis
Generally, osteoarthritis is divided into primary and secondary forms: primary osteoarthritis has no underlying cause; secondary osteoarthritis may be a result of trauma, previous inflammatory diseases such as rheumatoid arthritis, or crystal induced diseases.
Primary osteoarthritis is further broken down into the subsets of generalized osteoarthritis, erosive osteoarthritis, diffuse idiopathic skeletal hyperostosis, and chondromalacia patellae. These are discussed below.
Generalized osteoarthritis
Generalized osteoarthritis refers to osteoarthritis that affects the DIP (distal interphalangeal), PIP (proximal interphalangeal), and CMC (carpometacarpal) joints of the hands, but may also involve the neck, low back, hips, knees, and big toes (see illustration on page 5). There is usually a period where the joints are inflamed. Generalized osteoarthritis occurs primarily in middle-aged women.
Erosive osteoarthritis
This particular variant, which is usually inherited, involves the DIP and PIP joints and is associated with swollen, painful finger joints. The X-rays show erosions in the bone.
Diffuse idiopathic skeletal hyperostosis (DISH, or Forestier’s disease)
This is arthritis in the spine, in which huge flowing bone spurs (osteophytes) can be seen on X-ray between the vertebrae of the thoracic spine. Large bony spurs can also occur elsewhere, such as on the heels. Stiffness of the spine is the predominant symptom and pain may be surprisingly minimal.
Chondromalacia patellae
This is a condition seen in teenage girls, and more commonly in those who have had repeated trauma to the knee. They have knee pain that is made worse with squatting, kneeling, and going down stairs. What has happened is that the cartilage behind the kneecap has softened and split into fibres, and the kneecap has been allowed too much sideways movement because of looseness in its supporting muscles and tendons. What is needed is an exercise program to strengthen the muscles, after which the cartilage can go back to normal.
Symptoms
The joints that are commonly affected by osteoarthritis include the DIP, PIP, and CMC joints of the hands, the neck, lower back, hips, knees, and the big toes (or first metatarsal phalangeal joint). (See again the illustration on page 5.) If other joints are involved, it is usually as a result of trauma to that joint or an inflammatory arthritis (which will be discussed on page 15 of this chapter).
Pain
Pain is a predominant feature of osteoarthritis. Early in the disease, the pain accompanies movement, is aggravated by prolonged activity, and is made better with rest. When the condition is more severe, there is pain at rest and it will also awaken you at night.
The pain in osteoarthritis is not coming from the cartilage, which does not have nerve endings. The pain may be from the joint capsule, or from tendons around the joint that are being stretched because of the swelling or deformity of the joint. The pain may also be caused by stretching of the lining of the bone (periosteum) at the sites of new bone growth. If the bone spurs protrude into the space where the nerves travel (as in the neck or back) then the pain is from the nerve irritation or compression. Such a pain would travel down your arm or leg and would be a burning type of pain; there may be weakness or loss of feeling in the affected limb.
Stiffness
People with osteoarthritis often experience morning stiffness that usually lasts for less than 30 minutes.
Swelling
Once the cartilage has been damaged, bits of it actually cause an immune response and associated swelling, heat, redness, and pain (inflammation). Another cause of an acutely inflamed joint in osteoarthritis is the presence of calcium crystals in the joint space. Sometimes, the joint may appear to be swollen but it is actually enlarged as a result of the new bone growth. This is referred to as bony enlargement.
Crepitus
Crepitus is the grinding and creaking of the joint as it is being moved. This is common in osteoarthritis.
Deformity
The bony enlargement of the DIP joint of the finger is called a Heberden’s node. The enlargement of the PIP joint is called a Bouchard’s node. These can begin as a swelling like a cyst filled with jelly-like material. At times they become inflamed and painful. Once the inflammation has settled, they stop hurting and become hard and bony.
At the base of the thumb is the CMC joint, which can be involved with osteoarthritis. The joint can be very painful, like a boil, and becomes enlarged and bony. Often physicians refer to this as squaring of the joint.
There are two common deformities of the knees. The first, genu valgus or knock knees, occurs with loss of the lateral joint space of the knee and is more common in women. The second, genu varus or bow legs, is due to loss of the medial joint space of the knee and is more common in men.
The other common deformity of osteoarthritis is a hallux valgus deformity of the big toe: this is your common bunion.
Investigations
There are no specific laboratory tests for osteoarthritis: the diagnosis is based on the clinical findings and X-rays. This disease stays in the joints and the tests for inflammation (such as the ESR or the CRP) are usually normal.
The typical changes we see on X-ray include loss of cartilage, thickening of the bone under the cartilage, and bony spurs. You do not usually need more sophisticated X-rays, such as a CAT scan (computerized axial tomography) or MRI (magnetic resonance imaging). The MRI does show the cartilage changes better, however, and so would probably be used in clinical studies where it would be important to determine whether new therapies have an effect on the cartilage.
Management
The management of osteoarthritis includes treating the pain, maintaining the range of motion of the joints, and preventing disability. To do this, patients use medications, exercise, supportive devices, modification of daily activities, and surgery. To date, the most significant improvement in the management of osteoarthritis has been the replacement surgery for the knee and hip.
Medications
Medications are discussed much more fully and in more detail in Chapter 7, “Medications.” This section is intended to be an overview of medications available for treating osteoarthritis in particular.
No medication is currently available that repairs the cartilage, although considerable research is being done into the development of what are termed the “disease modifying osteoarthritic drugs.”
There is no harm in trying acetaminophen first. It should be taken on a regular basis, up to 650 mg (or two regular-strength pills) four times a day. If this is not working, then an NSAID (non-steroidal anti-inflammatory drug) can be tried, provided there is not a contraindication to its use. If you have had a previous bleed from a stomach ulcer, then you should be on something to protect your stomach (such as misoprostil or a proton pump inhibitor) or you could take a COX-2 selective drug, which is easier on the stomach. If you have high blood pressure, kidney problems, or congestive heart failure, then check with your physician before using an NSAID.
There are several topical agents used in osteoarthritis for pain control. Most of these contain capsaicin, which is derived from cayenne pepper. These products are rubbed over the skin three to four times a day, and may provide moderate relief of pain. There are also topical non-steroidal preparations, but the difficulty with these is that we don’t know how much is absorbed, and they have the potential for the same side effects as NSAIDs that you take by mouth.
There are several products that are labelled as viscosupplements (including Synvisc and Orthovisc). These are derivatives of hyaluronic acid, which is a naturally occurring part of the joint fluid, and they are given to supplement or add to what the body already makes. These drugs are given as a weekly joint injection (usually into the knee) for three weeks. They help with pain and improve mobility in 50–60 percent of cases. This effect lasts approximately six months to one year. Viscosupplementation works best in patients who have mild to moderate osteoarthritis of the knee.
Low doses of amitriptyline or other tricyclic antidepressant medications are very useful for pain control. They are used at night in small doses and they help you with sleep, have a direct effect on pain, and help relax your muscles.
Narcotics are occasionally recommended for the control of chronic pain and are sometimes necessary to control the pain of osteoarthritis.
As mentioned, disease modifying osteoarthritis drugs are not available yet, but glucosamine and chondroitin sulfate have been used to treat osteoarthritis. These are available in pharmacies and natural food and supplement stores. These products have been studied in Europe more than in North America, but the results to date suggest that both have an effect on pain, although the better designed studies showed them to have less of a benefit than placebo. Both are well tolerated; some people reported stomach upset, but this was mild. There may be an increase in b...
