Osteoarthritis
Topic Highlights
● Cartilage is connective tissue which cushions the ends of bones and allows the smooth movement of joints.
● The breakdown of cartilage causes the bones to rub against each other and leads to pain, discomfort, stiffness and loss of joint movement.
● The breakdown of cartilage is medically termed as osteoarthritis.
● This visual presentation describes the anatomy of joints, the pathophysiology of osteoarthritis, symptoms of osteoarthritis, the causes of osteoarthritis & risk factors, diagnosis of the disease, and treatment (non-pharmacologic, medications and surgical methods.)
Transcript
Osteoarthritis is the most common form of joint disease in humans. It varies tremendously in severity: while many people with osteoarthritis may not even know they have it, in others it can become serious enough to warrant surgical replacement of the affected joint.
This presentation is about joint health and what happens to the joints when they are affected by osteoarthritis. Various treatment options and ways to cope with the disease are also dealt with.
The word arthritis literally means inflammation of the joints, but it has come to be used for more than 100 different forms of joint disease. Osteoarthritis, the most common form of arthritis, is strongly associated with aging, although it is not a normal part of aging. It is so common in older people that it is becoming one of the most disabling diseases in the world. It is estimated that over 10% of men and 18% of women over 60 years of age have some form of osteoarthritis worldwide. Nearly 80% of those with symptomatic osteoarthritis have limited movements, and over 25% cannot perform simple daily activities.
Normal joints are made of two bones held together by ligaments and tendons, which are thick bands of elastic, connective tissue. The surfaces of the bones are covered with a semi-transparent layer of connective tissue called cartilage, which is elastic and flexible. Cartilage layers contain no nerves or blood vessels. Thus injury to the cartilage does not heal quickly. The main function of the cartilage is to cover the surface of joint bones, allowing smooth movement of joints and preventing the bones from wear and tear. It also acts as a shock absorber, preventing the bones from injury during movement or impact. The muscles attached to the joints also act as shock absorbers and help in keeping the bones together, as well as generating the force needed to move the joints.
The space between the bones in a joint is called the articular cavity. The capsule, which encloses this cavity, has an inner membrane called the synovium which secretes a clear, sticky fluid known as the synovial fluid into the space. The synovial fluid along with the cartilage assists in smooth, frictionless movement of joints, as well as nutrition of the cartilage.
Osteoarthritis is a disease that is characterized by focal, discrete areas of degradation of the cartilage surfaces of the joints. The cells of the cartilage, the chondrocytes, secrete the proteins, principally collagen, and proteoglycans that make up the structure of the cartilage. Like all other tissues in the body, these substances are undergoing constant turnover, and the cells can secrete enzymes that break down old areas of cartilage as well as secrete the chemicals that form the new structure or matrix. In normal, functional joints, these degenerative and regenerative enzymes are well balanced, allowing the cartilage to maintain its structure and function efficiently.
In osteoarthritis the normal balance of slow degradation and regeneration of the cartilage is disrupted, in favor of tissue breakdown. Over time this can lead to fissures or cracks appearing in the cartilage and so much loss of substance that the bone underneath is exposed. In addition there is a mild, variable degree of inflammation in the synovial lining of the joint, and a thickening of the capsule. But the slow process of developing osteoarthritis, which centers on those parts of the joint under most mechanical stress, is not confined to the cartilage. From the beginning the bone and other tissues are also affected. The ability of cartilage to repair is small. But bone is a very active, reparative tissue. The activity of the bone below areas of damaged cartilage increases greatly, the shape of the joint changes, and bone outgrowths appear at the margins of the joint– these are called osteophytes or bone spurs.
These reactions of the bone and soft tissues can be seen as an attempt by the joint to repair itself. The joint tries to repair itself and contain any abnormal mechanical stresses by splinting itself and changing its shape. At this stage, in some people, the disease may stabilize and although one may be left with a damaged joint, the disease stops progressing and the symptoms can improve.
Symptoms vary from person to person. Many people with X-ray evidence of osteoarthritis never experience any symptoms. The symptoms, if they do occur, include pain (particularly on use of the affected joint), discomfort, stiffness or swelling of the joint. One characteristic feature is the short-lasting but severe gelling of joints that occurs after resting them in one position; people with osteoarthritis find it difficult to get moving after inactivity and have to work their joints in as they start a new activity. Bony lumps in the edges of the joint may be tender and loss of flexibility can also occur. The joint may become larger and deformed. Back pain or neck pain can accompany osteoarthritis of the neck and spine joints. In people with osteoarthritis of the knee and hip joints pain while standing, walking and climbing stairs may occur.
The exact cause of osteoarthritis is unknown, but researchers believe it could be a combination of several factors like being overweight, aging, joint injury, having over used or deformed joints or heredity. Previously damaged joints are most likely to be affected, such as from an injury or from repetitive mechanical stress to the knees, hips, fingers, thumb base and lower spine. Diseases such as rheumatoid arthritis, or gout, that affect the structure and function of cartilage, can increase the risk of developing osteoarthritis later.
Osteoarthritis is diagnosed by examing a patient’s clinical history and by the completion of a physical examination at a doctor’s office. There is no definitive test for osteoarthritis. However, there are a variety of ways of imaging joints to assess the extent of damage to the cartilage surfaces, the bones and the soft tissues. Simple radiographs or X-rays are the most commonly used, but other options include bone scans, CT scans, MRI or direct visualization of the inside of the joint through an arthroscope. However, the severity of the damage shown on these images may not correlate with the likelihood of developing symptoms, the severity of symptoms or the long-term outcome of the disease. If there is doubt about the diagnosis, doctors sometimes recommend blood tests to help exclude other forms of arthritis. It may be helpful to perform an arthrocentesis where some of the synovial fluid is aspirated from the joint cavity using a needle and syringe for laboratory analysis.
Nonpharmacologic methods can be an effective adjunct to drug therapy in the treatment of osteoarthritis.
People with osteoarthritis would be advised to avoid any mechanical stress that could aggravate the condition. Mechanical devices like leg braces to help relieve the weight on damaged joints may be beneficial. A walking stick or cane can also help. Appropriate footwear that is comfortable and supports and distributes the body weight evenly is usually recommended. Poor posture causes uneven weight distribution and worsens strain on the muscles and ligaments, further weakening the joints. Hence maintaining a correct posture can help relieve pain.
In the case of osteoarthritis of the knee atrophy of the quadriceps muscles may occur due to disuse. The muscles in the quadriceps support the knee joint and, in addition to aiding in the movement of the limb, have the important function of protecting the articular cartilage from further wear and tear. Muscle-strengthening exercises, aerobic exercises and hydrotherapy are advised to prevent muscle atrophy and improve joint flexibility. Many people experience pain relief when heat and capsaicin cream are applied locally on the affected joint; while others find respite with ice fomentation.
Currently, there is no specific pharmacologic treatment for osteoarthritis that could interfere with the disease progression or modify the disease process or structure of the affected joint. Hence the treatment can only aim at alleviating the symptoms, particularly pain, and improving the flexibility and functionability of the affected joint.
Simple pain relievers like acetaminophen can help with mild to moderate pain without obvious inflammation. Non-steroidal anti-inflammatory drugs or NSAIDs may be prescribed if inflammation is also present and if acetaminophen does not help. Due to the risk of gastrointestinal toxicity of NSAIDs the doctor may add proton-pump inhibitors or misoprostol to the prescription. If the pain is severe and resistant to use of NSAIDs, the doctor may prescribe an analgesic like tramadol. Muscle relaxants may be prescribed for some people with osteoarthritis accompanied by muscle spasms. Narcotics like codeine may be added to an acetaminophen prescription in certain cases. However, they need to be used judiciously.
Some people may benefit from intraarticular joint injections of glucocorticoids. However, it is advisable to limit these injections to four a year per joint because of the risk of long term cartilage damage. Intraarticular injections of hyaluronic acid in the knee can provide symptomatic relief. These are given in a series of three to five injections, at intervals of one week each.
Surgical interventions are often the only recourse in severe cases of osteoarthritis where bone surfaces are exposed and eroding and when medical treatment alone is no longer effective. Although arthroscopic debridement and lavage are generally not recommended for cleaning the knee in osteoarthritis, a small number of people, particularly those with structural damage to the joint (as seen on imaging), may benefit from this procedure. A local anesthetic is administered through a small incision and a thin tube, that has a light and a camera and other devices attached to its end. The joint is then seen on a TV screen. During lavage, saline is flushed into the joint and the collected blood, fluid or pieces of tissue are flushed out. In debridement however, loose fragments of bone or cartilage that are still adhering to the bone surface are scraped out. These procedures can provide temporary relief from pain and inflammation.
Osteotomy, a procedure where the damaged bone may be shortened, lengthened or realigned, is an option for misaligned knee and hip joints, particularly in younger patients. Joint replacement surgery is the alternate procedure considered in older patients.
Arthroplasty, which literally means formation of joint, is absolutely the last line of treatment reserved for older patients in whom all forms of nonpharmacologic and drug treatments have failed and for those whose restricted mobility is severely affecting their everyday life. There are several forms of arthroplasty. The most commonly performed arthroplasty involves removal of damaged portions of bone, cartilage and soft tissue surrounding the joint and replacing it with prosthesis.
Research has shown that osteoarthritis can be prevented. Precautions taken early in life can help avoid the excessive wear and tear of weight-bearing joints. Some of the preventitive measures include losing excess weight, wearing comfortable and supportive footwear, maintaining correct posture and regular exercise.