Osteoarthritis (OA) is the most common joint condition in the world and affects hundreds of millions of people. It causes the largest amount of disability of any medical condition. Physiotherapy is extremely helpful in managing the long-term effects of OA.
A Normal Joint
Where two or more bones meet together is a joint. Our bodies have large numbers of different kinds of joints but the most common are called synovial joints. These include all our major mobility joints such as hip, knee, shoulder and ankle.
The surfaces of these joints are covered by articular cartilage, a firm, slippery material about 3mm or 1/8th of an inch thick. This allows painless and effortless movement of the joint even under load. A small amount of fluid is present and aids movement.
What is Osteoarthritis?
OA is a joint condition that changes the way the joint works and feels so it no longer moves smoothly. OA is also called degenerative joint disease, wear and tear, arthrosis and ostoearthrosis. They all refer to the same process now called OA. Modern thinking is that many of the joint tissues are involved in the process and not just the cartilage.
When Osteoarthritis develops these changes occur:
- The smooth articular cartilage thins out and roughens as it develops small cracks and flakes.
- The bone underneath the cartilage becomes denser.
- The lining of the joint produces more synovial fluid than normal and causes swelling in the joint.
- The joint tissues become more active to try and repair the ongoing damage so the joint may feel warmer than normal
In more severe cases:
- Severe loss of the cartilage layer may allow the bones to rub and grate together. This can be heard and felt as a crunching known as crepitus.
- Lumps can form as the bone around the joint grows outwards, making bony spurs known as osteophytes.
- The surrounding ligaments and joint capsule, designed to keep the joint stable, may thicken up and shorten. This limits the movement of the joint and may be the body’s reaction to a potentially unstable joint.
- Knock-knee or bow-leg may develop as the areas suffering the greatest loads also incur the worst arthritis changes.
These changes may result in pain, loss of movement and loss of muscle power.
The most common symptoms of osteoarthritis are:
- Pain. This is the main reason people go to the doctor. Mild stiffness and aching after heavy use will occur first in most people. This can then progress to a deep ache on activity. This may worsen until the joint is painful at rest or at night and troublesome on movement or weight bearing.
- Stiffness. The joint feels stiff on getting going so it will be very stiff in the morning but will ease within 30 minutes. The joint may stiffen or “gel” after resting for a period following exercise or activity.
- Grinding or grating feelings or noises, known as crepitus, are very common. Crunching and creaking can both be felt and heard in severe cases.
- Swelling. There are two types. One is the hard bony swelling of the joint caused by extra bone formation and the second is the extra fluid inside the joint.
- Wasting of the main quadriceps muscles may be evident.
- Loss of joint function. The joint may have restricted movement, loss of power and feel unstable. Hip and knee joint OA may limit getting up from chairs, climbing stairs and walking.
An osteoarthritic joint can vary from day to day and be worse or better for no obvious reason, perhaps in response to changes in the weather.
What Causes Osteoarthritis?
It is not clear what the cause of OA is but it is likely to be a mixture of genetic and life factors such as:
- Age. The incidence of OA increases for every decade of life and is estimated to occur on x-rays of 80-90% of people over 65. By 80 years of age everyone has some affected joints. Many people have no symptoms from their OA joints. Most people are over 50 before they have any symptoms, perhaps due to the chemical changes in cartilage and a reduced supply of nutrients.
- Gender. OA is more severe and more common in women, especially OA of the hand joints and the knees.
- Injury. An injury to a joint which changes the smooth surface or the angle of the joint can result in abnormal loads speeding up the degenerative process. Some demanding jobs, such as farming, increase the chances of getting OA.
- Repeated small joint insults may add up over time to damage a joint. This can occur in activities or jobs where frequent kneeling, stair climbing or squatting is involved.
- Obesity.Being overweight is related to developing osteoarthritis. Extra weight may contribute to worsening of the joint changes over time. This is particularly relevant to knees and may also be important in hips.
- Abnormalities of joints. Any joint abnormality may increase the likelihood of developing OA. Examples are DDH or development dysplasia of the hip, where the hip ball and socket fail to form normally and become arthritic in adulthood. There is a suspicion that most OA in hips or knees may be due to unrecognised defects in or damage to the joint.
- Surgery and trauma. Repair of the cartilage, ligaments and menisci (the small spacers in the knee) can restore normal function to a joint, but around 50-60% of patients develop osteoarthritis to some degree from five to fifteen years later.
- Genetics and Heredity. The only clear genetic link is for nodal osteoarthritis that affects the small hand joints in older women and runs in families. Some people have a defect in a gene that controls the manufacture of cartilage. This makes poor quality cartilage that may worsen more quickly than normal.
- Inflammatory arthritis. OA may develop due to joint damage from rheumatoid arthritis, gout or other arthritic conditions.
Which Joints Get Osteoarthritis?
While osteoarthritis can occur in any joint due to injury or abnormality it is much more common in certain joints, particularly weight bearing ones. It is often symmetrical, occurring to some degree in joints on both sides.
- Knees. Common in older people, especially women. If severe may lead to total knee replacement.
- Hips. Again common in older people and may require total hip replacement.
- Spinal. The small joints in the back and neck (not the major disc joints) can become arthritic and give stiffness, pain and limited movement.
- Hands. The small hand joints may develop bony swelling, become stiff and go off at angles to straight. The most common and troublesome is the joint at the base of the thumb.
- Big Toe. This joint is susceptible to changes in the same way as the base of the thumb.
Complications of Osteoarthritis
There are two joint conditions which are more likely to occur in people with Osteoarthritis:
- Gout. This is an inflammatory arthritis and is more common than realised. Higher levels of the chemical urate in the blood can lead to crystals being formed in and around a joint. This is more likely if the person already has OA. The big toe joint is the most common site for this disease and also a common place for OA to occur.
- Chondrocalcinosis. Crystals of a material called calcium pyrophosphate may form in a joint. This can occur without OA but is more common in older people with OA of the knee. This may speed up the worsening of OA and in some cases the crystals can bring on an acute arthritis. This causes a severely painful, hot and swollen joint. This is acute CPP or acute calcium pyrophosphate crystal arthritis.
There are over 100 different types of arthritis so it’s important to see a doctor for the correct diagnosis before planning the management. Treatments for different types of arthritis vary greatly so the appropriate treatment must be chosen.
Diagnosis of Osteoarthritis is done by noting the signs and symptoms:
- Pain on movement, either at the time or afterwards. This varies from a mild ache to severe pain.
- Morning stiffness, usually lasting for 30 minutes or so.
- Tenderness on handling of the joint, such as by a physiotherapist.
- Crunching and creaking on movement. This is called crepitus and can be felt and heard quite clearly in severe cases.
- Hard swelling around the joint. This is due to bony enlargement around the edges of the joint.
- Fluid swelling in the joint. Synovial fluid is secreted in larger amounts in an unhappy joint. After over activity or injury the swelling may be very tight and painful and need aspirating with a needle.
- Limited range of movement. The joint loses some of its movement and when pushed to the end of a movement it is usually painful.
- Abnormal movement and joint laxity. OA may lead to a joint becoming loose and moving abnormally which can worsen the joint’s condition over time.
- Loss of muscle size and strength. A painful joint inhibits the muscles around the joint so they work less and less well. This causes them to weaken and become smaller, reducing the stability and power of the joint further.
A doctor may ask for tests:
- X-rays. With most osteoarthritis joints this is not necessary as the diagnosis will be clear. However it can show the state of the joint to compare against future x-rays to monitor the progress of the condition. The amount of joint damage on x-rays is not well linked to how much pain or problems people have.
- MRI scanning. This is more suitable for looking at soft tissues such as the menisci, cartilage, ligaments, muscles and tendons. It can indicate problems with these which may need intervention. Since many changes on MRI are present in pain-free people, it is difficult to judge how important any particular change is.
- Blood tests. These are not useful in osteoarthritis but if the diagnosis is uncertain they may point to a different kind of arthritis.
The Prognosis For Osteoarthritis – How It’s Going To Go
We can't tell how osteoarthritis will progress in any one individual. It may come on quickly and become severe within only a few years as joint changes develop. This may progress to deformity such as knock-knee or bow-leg and become disabling.
More common is a slow process over years without sudden worsening or changes in the function of the joint. This type of OA is less likely to end up with a severely damaged joint.
The symptoms may wax and wane, or develop up to a worst point and then improve or change very little. OA is limited to the joints so there are no effects on other parts of the body as in inflammatory conditions such as rheumatoid arthritis.
Faster worsening of knee osteoarthritis is related to being older, being overweight, having knock-knee and many joints involved.
The aim of treatment for osteoarthritis is to reduce the pain and encourage normal joint movement and function. Osteoarthritis cannot be cured except by joint replacement. Non-surgical management of OA consists of:
Patient education. Patients need to understand what OA is and how it may change with time. And how it differs from inflammatory diseases such as rheumatoid arthritis. Weight loss and exercise can have significant benefits. Patients can learn good ways to control pain and improve the function of their joint.
Heat and cold. Ice or heat may be used, with care for the health of the skin an important issue. Individuals usually find out which one suits them.
Weight loss. The less weight the body has to bear the less stress on the joints and the easier it is to move about.Exercise. Bicycling and swimming can maintain overall fitness without excessive weight-bearing stress. Specific exercises to maintain muscle strength of particular joints are also useful.
- Physiotherapy. A physiotherapist can help with many of the treatments and management strategies mentioned here.
- Occupational therapy. An OT takes a functional approach to managing activities of daily living by changing behaviours and suggesting aids and appliances.
- Joint unloading. Using a stick or crutches can reduce the load on a hip or a knee and allow good mobility without so much pain.
- Drug treatments. Doctors prescribe a number of pain relieving drugs for OA. They start with paracetamol and anti-inflammatory drugs if medically appropriate. This may progress to codeine-based drugs. Topical anti-inflammatories, creams that are applied to the skin, may be useful. Always take a doctor's advice before starting any drug treatment.
- Overall, drug treatment has not been shown to be very effective in OA. And there can be significant side effects.
- Joint injections. Corticosteroid is injected into the joint but the scientific evidence of its usefulness is not clear. Visco-supplementation is the injection of a material similar to natural synovial fluid. This attempts to improve a joint's function.
- Surgery. If conservative treatment is not successful then a consultation with an orthopaedic surgeon may be useful. Arthroscopy may be used to trim worn structures within the joint but this has been shown not to be a useful treatment in the knee. Osteotomy can re-align the leg if there is significant bow-leg or knock-knee.
- Fusion, which is now less common, can stiffen a joint and allow a stable, painless joint. This is performed in joints which cannot easily be replaced, such as the big toe joint.
- In knee arthritis and meniscal problems, arthroscopy has been shown to have no positive effect in many cases. This treatment may be unnecessary.
- Joint Replacement. Knee replacement and hip replacement are successful procedures and both have a success rate of over 90%. On average they have to be re-done after ten to fifteen years which is usually a much more complex process. Younger people having joint replacements will have their new joints re-done more often.
Physiotherapy and Osteoarthritis
Physiotherapy is the main management for osteoarthritis once it is diagnosed and a joint replacement is not planned. A physiotherapist can help with:
Increasing muscle strength. This is vitally important for balance and normal activities. Regular exercise improves the use of a joint and weight-bearing exercise does not wear it out more.
Correct use of sticks or crutches. The correct pattern of use of walking aids is important to maintain normal walking and support the painful joint.
Improving walking ability and technique. Physiotherapists aim to keep walking patterns to as close to normal as possible as this maintains normal muscle activity and strength.
Reducing pain with paced activity and the use of hot or cold. Overdoing activity or doing too little can both increase joint pain and weakness.
Maintaining and increasing joint ranges of movement. Our joints move less far as we get older and keeping the movement can help a painful joint regain its normal use.
Unloading a joint with braces or splints. The idea is to reduce the stress on part of the joint to reduce pain.
Managing stairs and general mobility. Teaching people simple and safe ways of doing their activities of daily living (ADL) can improve quality of life.
Physiotherapists can perform a comprehensive assessment of a person's abilities when they are osteoarthritic. This allows a detailed treatment plan for the long-term management of the condition.
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- Osteoarthritis. Medscape – Author: Carlos J Lozada, MD; Chief Editor: Herbert S Diamond, MD | Mar 27, 2015
- Osteoarthritis – NHS – Introduction | 27/04/2015