Osteoarthritis of the knee

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Osteoarthritis, also known as degenerative joint disease, is the most common of the arthritides.

At least a quarter of persons over age 55 have had a significant problem with knee pain in the past year and severe cases can be disabling.

Osteoarthritis (OA) increases in prevalence with age and is more common in women than in men.

Osteoarthritis arises from wear of the articular cartilage, and may lead to secondary changes in the underlying bone.

It can be primary, or may occur secondarily to abnormal load to the joint or damage to the cartilage from inflammation or trauma.

With a large enough area of cartilage loss, or with bony remodeling, the joint becomes tilted and malaignment develops.

This creates a cycle of joint damage that can lead ultimately to joint failure.

Risk factors for OA include obesity, previous knee injury or surgery, and repeated strain through occupational bending and lifting.

In the Middle East, the prevalence of osteoarthritis may be linked to the prayer position, which can aggravate the knee joint.

OA is characterised by deep join pain that is relieved by rest.

In the knees, this pain is usually aggravated by activity, such as climbing stairs or walking long distances, because of the increased pressure on the patella.

Patients may have some morning stiffness lasting less than 30 minutes, exhibit crepitus on active motion and, in some cases, have bony enlargements.

The American College of Rheumatology’s criteria provides guidelines for diagnosis, with or without using radiographic or laboratory findings.

Blood tests are not routinely indicated in the work-up of patients with chronic knee pain, unless it is necessary to rule out rheumatoid arthritis or other forms of inflammatory arthritis.

Radiography may be required if knee pain is nocturnal or not activity-related.

 Pharmacologic treatmentMost current medical therapies primarily address the treatment of joint pain.

Acetaminophen, the active ingredient in Tylenol, is the first-line drug for knee pain because it’s considered safer than the nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen.


But acetaminophen certainly has dangers.

Patients shouldn’t take more than 4,000 milligrams a day because of the risk of liver problems.

However, acetaminophen appears to be less effective among patients who have already been treated with NSAIDs.

One crossover trial showed there was no improvement overall with acetaminophen in patients treated after a six-week course of NSAIDs.

Patients may benefit from a switch to an NSAID if acetaminophen isn’t working, and including a misoprostol or proton-pump inhibitor, such as esomeprazole (Nexium), with an NSAID can prevent some gastrointestinal side effects.

This technique has been shown in randomised trials to reduce the number of endoscopically confirmed ulcers associated with NSAIDs.

- Hyaluronic acid

Hyaluronic acid injections have been approved by the Food and Drug Administration (FDA) for the treatment of OA.

Hyaluronic acid is a component of the synovial fluid that lubricates the knee, as well as other joints.

Products on the market include Hyalgan, Orthovisc, Supartz, and Synvisc.

Patients are treated through a series of injections.

However, there is disagreement over the effectiveness of the treatment.

Boston University osteoarthritis expert Dr David T. Felson is a skeptic, and considers hyaluronic acid to be a “very expensive placebo”.

He argues that study findings haven’t been impressive, adding that injected hyaluronic acid doesn’t stay in the joint for much more than a day, and so it’s doubtful that it could act as a long-term lubricant.

Certainly, data on the efficacy of the treatment is inconsistent.

A meta-analysis, published in the Journal of the American Medical Association, reported statistically significant but limited efficacy.

A second meta-analysis also identified two large, unpublished trials whose data showed no efficacy and observed that the treatment seemed less effective in large than small trials.

- Corticosteroid injections

An editorial in the British Medical Journal several years ago claimed the pain relief from cortisone injections is almost immediate and the improvement in mobility “magical”.

Intraarticular cortisone injections have been shown in trials to relieve pain more effectively than placebo for one to three weeks on average.

However, after this period, their efficacy wanes.

Still, if a patient needs to be free of knee pain for a vacation or family event, or just has a bad flare-up, a cortisone shot is a reasonable choice.

- Capsaicin cream

Capsaicin is a substance derived from chili peppers.

The theory behind its use as a topical compound is that the strong, irritating sensations of capsaicin compete with pain signals from the arthritic knee so the pain signals can’t get through.

Studies have shown capsaicin to be moderately better than placebo in reducing OA pain of the knee.

- Glucosamine and chondroitin sulfate

There is no cure for OA, which leaves ample room for hope, hype and halfway measures.

Alternative therapies are widely used, such as the dietary supplements glucosamine and chondroitin sulfate.

These supplements have been advocated, especially in the lay media, as safe and effective options for the management of symptoms of osteoarthritis.

Glucosamine, made from shellfish, and chondroitin, which is made from cow cartilage reportedly work by rebuilding cartilage but the mechanisms of their action is unclear.

Every day millions of people take the supplements and most doctors have had a tolerant attitude about this.

Conventional medicine doesn’t have any sure thing.

Knee replacements are major surgery and a last resort.

If the supplements don’t do any harm, why not give them a try?

But doing no harm doesn’t mean doing any good, either.

There have been scores of studies of glucosamine and chondroitin, but many of them have been small, sponsored by groups with a vested interest, or both.

In response, the US-based National Institutes of Health (NIH) is running several of the popular ones through the gauntlet of large clinical trials.

The NIH-funded Glucosamine/chondroitin Arthritis Intervention Trial, or GAIT, included 1,583 people with symptomatic knee osteoarthritis.

The researchers randomised them to take the supplements in various combinations or placebo pills, and then asked the volunteers to grade their knee pain six months later.

The results, which were published in the February 2006 edition of the New England Journal of Medicine, showed no difference between the placebo pills and glucosamine and chondroitin.

Supporters have argued the door is still ajar, because a subgroup analysis showed some benefit from the supplements among people with more severe cases of osteoarthritis.

But subgroup analyses are inherently suspect because the number of subjects involved is generally small, and positive findings may occur just as a matter of chance.

There’s also some question about the glucosamine compound tested in the trial and whether it has the same effect as the glucosamine sulfate now being sold.

As with the results of every study, the average result may not apply to everybody.

Some patients are convinced by the relief they get from glucosamine and chondroitin and, while that could be just a placebo effect, it may be true for some.Nonpharmacologic treatmentThe role of exercise is crucial for patients with OA.

Aside from strengthening muscles, exercise can aid in weight loss, which can help relieve knee pain, and guard against obesity.

Obesity is a powerful risk factor for the development of knee OA, with one twin study finding a 9 to13% increased risk for the onset of the disease with every kilogram increase in body weight.

But exercise can make knee osteoarthritis worse if patients are not careful.

Pain and swelling can have an inhibitory effect on muscles, reducing their strength.

Exercise that is too stressful can make this worse, resulting in further weakening of the very muscles that need to be strengthened.

Following the “no pain, no gain” motto is counterproductive.

To be effective, strengthening exercises should be gradual and not provoke greater knee pain.

Prescribing a knee brace, orthotics, or both to correct malalignment before patients begin an exercise programme may make a difference.

In patients with OA, weakness of the quadriceps muscles occurs through disuse and arthrogenous muscle inhibition.

Muscle strengthening here is important because stronger muscles improve the stability of the joints, helping to lessen pain.

However straight-leg lifts, a popular way of strengthening the quadriceps, are not recommended.

Exercises are more likely to be effective if they train muscles for the activities a person performs daily.

Randomised trials have shown that isokinetic or isotonic strengthening (where a person flexes or extends the knee against resistance) and low-impact aerobic exercise are both effective in lessening pain.

Exercise shouldn’t put too much weight on the knee and or that reason, pool workouts are ideal.

Cycling may also help patients and has the added benefit of offering a cardiovascular workout.

However, depending on how hard a person cycles, it can load the patellofemoral joint, so it may not be suitable for patients with patellofemoral symptoms.

Ideally, exercise programmes should be custom-made for the patient and supervised by a physical therapist.Ongoing knee protectionAdvising patients to purchase a good pair of running shoes is a good place to start.

Running shoes are made to accommodate either pronation or supination.

Knee supports may also benefit patients.

They may help give added stability because the pressure on the skin provides a sensory cue to the muscles to contract when needed, even though sleeves do little to change biomechanics or alignment.

In a trial of patients with osteoarthritis of the medial side of the knee and varaus malaligment, wearing a sleeve decreased pain moderately when compared to no treatment.

In addition, there are over-the-counter (OTC) wedged insoles or orthotics that fit into the shoe.

They can help patients who have a mild case of osteoarthritis.

But the brands sold in pharmacies can pose problems.

Most are made so that they’re thicker on the inside edge, which may be more suitable for valgus malalignment and not helpful for patients who are varus.

Orthotics can also make foot and ankle problems worse.

In short, they may be worth a try, but patients should be monitored to ensure that they aren’t aggravating the problems.

Lastly, there are OTC knee braces, but these are only suitable once knee problems have been properly diagnosed and analysed.

A good knee brace needs to be custom-made.

Design has improved, but they’re still bulky, and may not fit under trousers.

You may find that getting patients to wear the knee brace is one of the biggest challenges, but if the osteoarthritis is really bad, patients are often than willing.

Some patients may benefit from a referral to a specialist, such as an orthopedist, for issues with biomechanics; a rheumatologist, for osteoarthritis and inflammatory problems; and a physical therapist for rehabilitation.

“Results from the NIH-funded Glucosamine/ chondroitin Arthritis Intervention Trial, or GAIT, showed no difference between the placebo pills and glucosamine and chondroitin.”


“Obesity is a powerful risk factor for the development of knee OA, with one twin study finding a 9 to 13% increased risk for the onset of the disease with every kilogram increase in body weight.”

At a glance: American College of Rheumatology clinical- Using history and physical examination Pain in the knee and any three of the following:

- Over 50 years of age

- Less than 30 minutes of morning stiffness

- Crepitus on active motion

- Bony tenderness

- Bony enlargement

- No palpable warmth of synovium

- Using history, physical examination and radiographic findings

- Pain in the knee and any one of the following:

- Over 50 years of age

- Less than 30 minutes of morning stiffness

- Crepitus on active motion and osteophytes

- Using history, physical examination and laboratory findings Pain in the knee and any five of the following:

- Over 50 years of age

- Less than 30 minutes of morning stiffness

- Crepitus on active motion

- Bony tenderness

- Bony enlargement

- No palpable warmth of synovium

- ESR <40mm/hour

- Rheumatoid Factor (RF) <1:40

- Synovial Fluid (SF) signs of osteoarthritis

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