Bones, joints, and muscles

What is osteoarthritis?

Also known as degenerative joint disease, osteoarthritis is the most common form of arthritis. It occurs in adults over the age of 60 and is generally caused by wear and tear of joints over time. It's believed that chemical and genetic factors also play a role in the development of osteoarthritis. Although osteoarthritis is more common in older adults, it can develop in people under the age of 60. Risk factors such as poor posture, overweight or obesity, congenital bone or joint deformities, and injury can also contribute to the onset of osteoarthritis in people under the age of 60. Severe osteoarthritis is three times more common in women than in men.¹

Those joints most likely to be affected by osteoarthritis are the weight-bearing joints. Symptoms of osteoarthritis include pain, stiffness, and swelling of the affected joints. In some instances, movement of the joints is accompanied by creaking or cracking sounds.²

Anatomy of a joint

Consider the anatomy of a joint. Joints consist of several bony surfaces shaped to fit together in order to move freely and bear weight. The weight-bearing joints of the body include the neck, hips, knees, and lower back. The main parts of a joint include cartilage, the synovial membrane, the bursa, tendons, and ligaments.

Cartilage

Cartilage is a strong smooth material that provides cushioning at the end of each bone in the joint. Cartilage acts as a shock absorber and prevents bones from rubbing against each other. The main feature of osteoarthritis is irritation and inflammation of the cartilage that covers the ends of bones. Osteoarthritis occurs when the protective cushioning of cartilage covering the end of the bones becomes soft and begins to wear unevenly. Eventually, pieces of roughened cartilage break off and move freely within the joint. If the layer of cartilage suffers sufficient damage, the bone underneath will be left unprotected, leading to the development of osteophytes. These osteophytes—outgrowths of new bone—often cause pain and reduced movement of the joint. In some cases, thickening of the ends of the bone may occur.³

Synovial membrane

Joints are enclosed by a tough fibrous capsule which is lined with a tissue known as the synovial membrane. The synovial membrane encloses the synovial sac, a sac filled with synovial fluid that nourishes the cartilage and helps protect and lubricate the joint. It's important to remember that cartilage has no blood supply and relies on the movement of synovial fluid to bring in nutrients and to flush out waste. This is why exercise is particularly important in the treatment of osteoarthritis. Encouraging movement through exercise helps improve the health and nutrition of the cartilage.⁴

Bursa

Although not actually part of the joint, the bursa, like the synovial sac, provides lubrication. The bursa lubricates the movement of muscle over muscle and of muscle over bone. Inflammation of the bursa is known as bursitis.⁵

Muscles

The contraction and expansion of muscles is what allows joints and bones to move.

Tendons

Tendons are the fibrous cords that attach muscles to bones. Inflammation of tendons results in the condition known as tendinitis.

Ligaments

Ligaments are similar to tendons in that they are also fibrous cords. Unlike tendons which attach musucles to bones, however, ligaments attach bones to bones, making up the joint capsule.

How does osteoarthritis affect joints?

It's thought that osteoarthritis is caused by cellular changes within cartilage—changes that lead to a loss of elasticity. Such cellular changes lead to a breakdown of the cartilage and inflammation of the synovial membrane. As the cartilage breaks down, small particles may break off into the synovial membrane, moving freely within the joint space and causing further irritation and inflammation. As the condition progresses, the cartilage continues to break down, possibly to the point of leaving bones unprotected. Consequently, the joint loses its smooth functioning. Over time, bones within the joint may lose shape and thicken at the ends, producing bone spurs or outgrowths called osteophytes.⁶

Although osteoarthritis can affect any synovial joint in the body, it occurs most commonly in the following:⁷

• the hands—osteoarthritis of the hands occurs commonly in women, affecting the end finger joints and producing bony growths known as Heberden's Nodes
• the base of the thumb
• the spine—osteoarthritis of the spine affects the neck and lower back, as well as the discs between vertebrae.
• the major weight-bearing joints such as the knees and hips; osteoarthritis of the hip is more common in middle-aged and older adults and can be quite severe
• the knee—osteoarthritis of the knee is often linked to a previous injury, such as a sports or repetitive injury. Being overweight exacerbates this condition.
• the shoulder, ankles, feet, and toes

What are the symptoms of osteoarthritis?

Most people suffering from osteoarthritis experience severe pain and stiffness around the joint, regardless of whether the joint is at rest or in movement. In other people, symptoms may be mild and exacerbated by periods of increased use or minor injury. Symptoms will vary depending on the joints affected and their use. Redness around the joint and weakness of the joint, as though it is about to give way, is another common complaint.

Diagnosing osteoarthritis

If you have any symptoms of arthritis and you suspect you may have the disease, consult your physician or other health care provider. Early diagnosis and treatment may mean less disability in the long run. Your doctor can diagnose arthritis through physical examination, x-rays, and bloodwork. He or she may also draw fluid from the joint(s) for analysis. Once a firm diagnosis of osteoarthritis has been made, your doctor can then set up a treatment program to reduce the pain and disability associated with osteoarthritis.

Treating osteoarthritis

Although at present there is no cure for osteoarthritis, a number of known treatments and management techniques are available, allowing patients to control and reduce the effects of the condition. Studies have shown that those who exercise regularly and who practice meditation and relaxation have less pain and are more active. As explained, exercise brings many benefits to those living with osteoarthritis. Encouraging movement through exercise helps improve the health and nutrition of the cartilage. Exercise also helps to:

• decrease pain
• increase the mobility of joints
• increase muscle strength
• strengthen bones and ligaments
• prevent joint deformities
• nourish joints
• increase overall fitness and well-being

Activities such as walking, swimming, low-impact exercise classes, tennis, lawn bowling, and Tai Chi are just some of the types of gentle exercise recommended by health practitioners in the treatment of osteoarthritis. Many recommend aquacise classes because the buoyancy and warmth provided facilitates joint movement.⁸

Symptomatic treatment of arthritis may include heat, physical therapy, and aspirin, corticosteroids, or nonsteroidal anti-inflammatory medications such as acetominophen, ibuprofen, or naproxen. Remission can sometimes be achieved through penicillamine, gold salts or steroids, but these medications can often have undesirable side effects including gastrointestinal bleeding, hypertension, cataracts, thinning of bones, upset stomach, and increased infections. In severe cases of arthritis, orthopedic surgery, including artificial joint implants, may be necessary.⁹

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