Knee Osteoarthritis: Causes, Symptoms, Stages, Risk Factors and Treatment

Also called osteoarthritis, it is a degenerative disease that affects the joints.

It is known as a ” wear and tear ” disease . Although it is not caused by ages, the number of Canadians affected by it is increasing by 5% each year due to the aging of the population.

The symptoms that people experience are caused by the loss or breakdown of the cartilage in the knee, which leads to a narrowing of the space in the joint.

This loss of joint space progresses as time passes, giving rise to bone spurs and decreased movement.

Causes and risk factors

Osteoarthritis of the knee can develop as a result of a number of factors. Age is the most common risk factor associated.

It is important to remember that although age does not cause osteoarthritis of the knee, older adults (especially women) are still the most affected due to the degenerative nature of the disease.

It is estimated that 85% of Canadians older than 70 years will have Osteoarthritis. Other risk factors include:

  • Genetics.
  • Gender.
  • Obesity.
  • Biomechanics of altered knee.
  • Injury or previous trauma.
  • Repetitive stress injuries.

Treatment for knee arthritis

Several types of treatment can help arthritis of the knee. Taking nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen or aspirin, can temporarily relieve arthritis pain and decrease inflammation in the knee joint.

Other medications for arthritis include:

  • Analgesics, which help with pain and can be recommended as an alternative to NSAIDs.
  • Corticosteroids, which help with inflammation.
  • Biological response modifiers, which can help prevent your immune system from causing joint inflammation.
  • Disease-modifying antirheumatic drugs (DMARD), which can help specifically with RA.

Injections that can help with knee arthritis include:

  • Hyaluronic acid supplements, which relieve the inflammation and pain of arthritis by lubricating the joints of the knee to allow a smoother movement.
  • Corticosteroid injections, which are injected into the knee to calm inflammation and pain.
  • Arthrocentesis, in which fluid is removed from the joint with a needle to perform the test (it can also relieve pain).

You may need surgery for your arthritis, even if other treatments help with your pain. Three types of surgeries are more common to treat knee arthritis:

  • Total joint replacement: the most common type, in which your doctor replaces your knee with a prosthesis made of plastic, ceramic or metal.
  • Osteotomy: in which your doctor modifies the bones of your knee to control the damage and pressure in your knee.
  • Arthroscopy: in which your doctor makes an incision in your knee to remove or repair damaged parts.

Talk to your doctor about what treatment or procedure is best for you, based on your level of pain, how much your arthritis affects your daily life and the damage it causes to your knee.

Home remedies and lifestyle changes

Certain types of exercise can help preserve knee function and pain relief, including water aerobics, strength training and tai chi .

Losing weight, especially if you are overweight, can help relieve osteoarthritis of the knee by decreasing the pressure on your knees.

Some studies have suggested that the following supplements may help relieve the inflammation and pain caused by knee arthritis:

  • Capsaicin
  • Turmeric.
  • Chondroitin sulfate.
  • Glucosamine
  • Soy avocado.


There are many symptoms of osteoarthritis of the knee, and its severity depends on how advanced your condition is. Although, you may not have all the symptoms associated with osteoarthritis of the knee, you can have it if you have any of these symptoms:

Swelling or sensitivity:

Arthritis of the knee can cause periodic inflammation. This may be due to the formation of bone spurs (osteophytes) or extra fluid in the knee.

Inflammation may be more pronounced after a long period of inactivity, such as when you wake up in the morning.

The skin of the knee may look red or feel warm to the touch. Over time, you may experience a chronic inflammation of the knee that does not improve with over-the-counter or anti-inflammatory medications.


Over time, the muscles in your knee may weaken and the entire structure of the joint may become unstable. The general weakness of the knee can cause it to buckle or bend.

The joint can also stick or lock so you can not bend or straighten it. You may find that these symptoms appear and disappear.

Poor range of movement:

Arthritis can make it harder and harder for the knee joints to slip as they should, making it difficult or impossible for previously simple movements to be a common symptom of arthritis. You are more likely to notice a restricted range of motion when climbing stairs or participating in sports activities.

Arthritis of the knee progressively wears out the cartilage. And, as the arthritis worsens, it becomes more difficult for the joints to function normally and it can be increasingly difficult to perform everyday tasks. Over time, you may have trouble walking without a cane or walker.

Loss of joint space:

X-rays of the knee are an excellent diagnostic tool because they clearly show the loss of joint space that causes sounds and a poor range of motion.

The space that normally occupies the cartilage wears out and the exposed bone is present. Bone spurs develop along the edges of the joint and reflect the body’s attempt to repair itself.

Deformities of the knee:

As arthritis progresses, you may notice changes in the appearance of your knee. Arthritis can create a sunken appearance because the muscles around the knees weaken.

Your knees may begin to point toward each other or bend outward. The deformities of the knee range from barely noticeable to quite severe and debilitating.


Crepitose is the medical term for the crunching sensation you may feel or hear when you move or bend your knee. Depending on how advanced your knee osteoarthritis is, you may feel or hear (or sometimes both) sounds when moving the knee joint like:

  • Crisp sounds
  • Sounds like cracklings.
  • Sounds as if something was grinding.


Pain, sensitivity or discomfort are often felt on the inside of the knee with osteoarthritis. This is because your body distributes its weight directly down, exerting additional pressure on the inside of the knee joint.

However, some people experience symptoms of osteoarthritis of the knee on both sides of the knee or only on the outside of the knee joint.

The pain of osteoarthritis of the knee usually worsens at the end of the day and improves with rest. With this condition, you may feel pain or sensitivity when:

  • Kneels.
  • Walk uphill or downhill.
  • Go up stairs or down stairs.
  • Bend the knee.


While osteoarthritis associated with pain may improve with rest, excessive rest will result in stiffness in the knee joint.

The rigidity usually lasts a few minutes and decreases with movement and gentle stretching.

If you have noticed that your knee becomes stiff after sitting for a while, or is stiffer on getting up in the morning, you may have osteoarthritis of the knee. With osteoarthritis your knee may feel stiff:

  • For short periods in the morning.
  • After a prolonged rest.
  • After sitting for a long time.

Loss of mobility:

Osteoarthritis of the knee can cause loss of daily functioning, since the knee does not move as freely as it should.

Pain, sensitivity and stiffness cause many people with osteoarthritis to see a decrease in their mobility, this can make it difficult:

  • Sit or get up from the chairs.
  • Enter or exit cars.
  • Climb or descend stairs.

Stages of osteoarthritis of the knee

Osteoarthritis is divided into five stages. Stage 0 is assigned to a normal and healthy knee. The highest stage, 4, is assigned to a serious condition.

Osteoarthritis of the knee that has evolved to this advanced process is likely to cause significant pain and alter joint movement.

Stage zero: Normal.

The knee joint shows no signs of osteoarthritis and joint functions without any deterioration or pain.

  • Treatment: No treatment is needed for stage zero osteoarthritis of the knee.

Stage one: Minor – Little or no pain or discomfort.

A person with stage 1 knee osteoarthritis shows very mild bone spur growth. Bone spurs are bone tumors that often develop when the bones are in the joint.

In stage one, there is already a small loss of cartilage (around 10%). The osteophytes, small bony outgrowths, also may begin to grow in the knee joint.

While there is some loss of cartilage, there is little or no narrowing of the joint space between the bones.

  • Treatments: Without external symptoms of osteoarthritis to treat, many doctors will not require you to undergo any treatment for Stage 1.

However, if you have a predisposition to osteoarthritis or are at higher risk, your doctor may recommend taking supplements, such as glucosamine and chondroitin, or start an exercise routine to relieve any minor symptoms of osteoarthritis and slow the progression of arthritis.

Stage two: Mild – some joint pain and stiffness.

The damage to the knee joint at this stage is even less; the bones do not rub or scrape each other.

There is a continuous loss of cartilage and a remarkable growth of osteophytes.

While the space between the joints (joint space) remains healthy, the places where the bones make contact begin to harden, along with the surrounding tissues.

X-rays of the knee joints at this stage will reveal increased growth of the bone spur, but the cartilage generally remains healthy, ie the space between the bones is normal and the bones are not rubbed or scraped together .

In this stage, synovial fluid is also typically present at levels sufficient for normal movement of the joint.

However, this is the stage where people may begin to experience symptoms such as pain after a long day of walking or running, increased stiffness in the joint when not used for several hours, or sensitivity when kneeling or bending.

Treatments:  Talk to your doctor about possible signs of osteoarthritis. Your doctor may be able to detect and diagnose the condition at this early stage. If so, then you can develop a plan to prevent the condition from progressing.

Several therapies can help relieve the pain and discomfort caused by this mild stage of osteoarthritis. These therapies are mainly non-pharmacological, which means you do not need to take medications to relieve the symptoms.

If you are overweight, losing weight through diet and exercise can alleviate minor symptoms and improve your quality of life. Even people who are not overweight will benefit from the exercise.

Low-impact aerobics and strength training can help strengthen the muscles around the joint, which increases stability and decreases the likelihood of additional joint damage.

Protect your joint from effort by avoiding kneeling, squatting or jumping. Clamps and bandages can help stabilize your knee. Shoe inserts can help realign the leg and relieve some of the pressure it exerts on the joint.

Some people may require medications to relieve mild pain. These are generally used together with non-pharmacological therapies. For example, if you need to take Acetaminophen to relieve pain, you should also try to exercise, lose weight and protect your knee from unnecessary stress.

Long-term therapy with these medications can cause other problems. Anti-inflammatories can cause stomach ulcers, cardiovascular problems and kidney and liver damage. Taking larger doses of paracetamol can cause liver damage.

Stage 3: Moderate – Pain, discomfort and swelling.

In stage three, there is a marked loss of cartilage and the joint space has been markedly reduced. At this stage the swollen and inflamed joint is also seen.

People with osteoarthritis of stage 3 of the knee are likely to experience frequent pain when walking, running, bending, or kneeling.

They may also experience joint stiffness after sitting for long periods of time or waking up in the morning.

Joint inflammation may also be present after long periods of movement.

Treatment:  If the non-pharmacological therapies do not work or no longer provide the pain relief they once had, your doctor may recommend cortisone injections .

Cortisone, a steroid produced naturally by your body, has been shown to relieve pain caused by osteoarthritis when injected near the affected joint.

The effects of a shot of cortisone disappear in about two months. However, you and your doctor should carefully consider the use of cortisone injections. Research shows that prolonged use of the steroid can actually worsen joint damage.

If over-the-counter anti-inflammatories or paracetamol are no longer effective, prescription pain medications, such as codeine and oxycodone, may help relieve the increased pain that is common in stage 3 of osteoarthritis. In the short term, these medications can be used to treat moderate to severe pain.

However, narcotic medications are not recommended for long-term use due to the risk of increased tolerance and possible dependence. Side effects of these medications include nausea, drowsiness and fatigue.

People who do not respond to conservative treatments for physical therapy with osteoarthritis, weight loss, use of anti-inflammatories and analgesics, may be good candidates for visco-supplementation.

Viscosuplementos are intra-articular injections of hyaluronic acid. A typical treatment with a viscosuplemento requires one to five injections of hyaluronic acid, one week apart.

There are some injections that are available as a single dose injection. The results of a viscosupplementation injection are not immediate.

In fact, it may take several weeks for the full effect of the treatment to be felt, but relief of symptoms usually lasts a few months. Not everyone responds to these injections.

Stage 4: Severe – Intense pain, discomfort, loss of mobility.

The fourth stage is the most advanced with 60% of the cartilage of the worn knee. The space of the joint narrows significantly when the bones touch each other.

The friction caused by the bones rubbing each other causes significant inflammation. Patients in this stage of osteoarthritis of the knee usually observe the growth of more osteophytes, experience intense pain and, in very severe cases, the bones can be deformed.

It is possible to have osteoarthritis in stage four with minimal or no pain at all. Therefore, if you think you may have osteoarthritis of the knee, it is best to make an appointment with a qualified physiotherapist to obtain a complete evaluation.

People in stage 4 of osteoarthritis of the knee experience great pain and discomfort when they walk or move the joint.

This is because the joint space between the bones is drastically reduced: the cartilage is almost completely gone, leaving the joint rigid and possibly immobile.

Synovial fluid is drastically reduced and no longer helps reduce friction between the moving parts of a joint.

Treatments:  Bone realignment surgery, or osteotomy, is an option for people with severe osteoarthritis of the knee. During this surgery, a surgeon cuts the bone above or below the knee to shorten, lengthen or change its alignment.

This surgery shifts the weight of your body away from the tips of the bone where the greatest growth of bone spines and bone damage occurred. This surgery is often done in younger patients.

Total knee replacement, or arthroplasty, is a last resort for most patients with severe osteoarthritis of the knee. During this procedure, a surgeon removes the damaged joint and replaces it with a plastic and metal device.

Side effects of this surgery include infections at the site of the incision and blood clots. The recovery of this procedure takes several weeks or months and requires extensive physical and occupational therapy.

It is possible that the replacement of your arthritic knee is not the end of your knee osteoarthritis problems. You may need additional surgeries or even another knee replacement during your life, but with newer knees, it can last for decades.

When to see the doctor?

Consult your doctor if your pain or inflammation does not respond to any type of treatment. Also consult your doctor if the pain interferes with your daily life, especially if you can not sleep or if the pain affects your walking or movement.

To diagnose your knee arthritis, your doctor will first assess your general physical health. You may be asked to stop while taking x-rays to see if you have arthritis.

They can also order a bone scan or MRI to examine their knees for arthritis.

Knee pain may indicate that you have osteoporosis, in which your bones lose their density and become more fragile. This condition can cause pain and discomfort similar to that caused by arthritis.

Your doctor may order a bone mineral density test to rule out osteoporosis as the cause of your pain.

Your doctor may also test you for lupus , a chronic disease in which your immune system attacks your body. Lupus can cause joint pain and other symptoms that can affect the functioning of your body.

Early diagnosis of knee arthritis can help you find treatments and therapies that relieve pain and preserve your ability to move without pain or difficulty.

If knee pain is interfering with daily activities, consult your doctor as soon as possible.