Osteoarthritis (OA) is a degenerative joint disease that can affect the knees. Treatments include knee injections and a partial or complete knee replacement.

This article outlines two main therapies for OA of the knee: knee injection therapy and knee replacement surgery.

It also outlines the side effects and risks that are associated with these treatment approaches and offers some tips on easing knee pain at home.

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OA is a chronic condition that causes the breakdown of cartilage between the joints.

Cartilage provides a smooth, slippery surface, allowing the bones to glide against each other. Without this surface, bones can rub or grind against each other, causing pain, stiffness, and swelling.

Knee injection therapy or knee replacement surgery can provide relief from the symptoms of knee OA.

There are also other ways a person can relieve the symptoms, including:

  • prescribed or over-the-counter (OTC) pain medication
  • physical therapy
  • losing weight

Arthritis is a spectrum, and different treatments are appropriate for different stages.

In the early stages, knee injections or lifestyle changes may be appropriate. Severe OA may need a partial or total knee replacement.

Learn more about osteoarthritis of the knee.

In the early stages, a doctor will use nonsurgical methods to treat OA of the knee.

Knee injection therapy is one of these methods. It involves injecting medications directly into the knee joint to help alleviate localized inflammation and pain.

Below are some of the different knee injection therapies that are available to a person with OA of the knee.

Corticosteroid injections

Corticosteroids are a class of medications that help to suppress the immune system and reduce inflammation.

A doctor can inject corticosteroids directly into a joint, such as the knee. These injections can provide relief from pain and inflammation.

Doctors can administer the injection in a hospital, clinic, or another medical facility. They may numb the knee area before injecting the corticosteroid drug directly into the joint.

Some people get increased swelling and pain in the joint immediately after the injection, but after a few days, this should go away.

Corticosteroid injections provide temporary relief from knee pain and inflammation. Depending on the condition of the knee, the benefits can last from a few days to several months.

Side effects

Most people do not experience any adverse effects after a steroid injection besides a little pain or tingling at the injection site.

However, corticosteroid injections can cause dangerous side effects for some people, especially those who receive repeated injections.

Side effects may include:

  • osteoporosis of nearby bone tissue
  • osteonecrosis, which is the death of bone tissue
  • a temporary flare of pain and inflammation in the joint
  • joint infection
  • nerve damage
  • thinning or lightening of the skin and soft tissue around the injection site
  • allergic reaction
  • elevated blood sugar levels in some people with diabetes

Viscosupplementation

These types of injections are sometimes called hyaluronic acid (HA) injections.

Hyaluronic acid is a substance that exists naturally in joint fluid. It acts as a shock absorber between bone surfaces and helps the bones to glide smoothly over one another.

In knee OA, there is a reduction in the quality and quantity of hyaluronic acid in the joint fluid.

A doctor may recommend an injection of hyaluronic acid directly into the knee joint to supplement the naturally occurring HA. The theory is that this may reduce pain and improve mobility.

However, according to OrthoInfo, the most recent research has not found this method to be effective at reducing pain or improving function.

Doctors may recommend this procedure to people who have already tried all other nonsurgical treatment methods.

People who do experience pain relief usually report this after several weeks. Some people report that the pain-relieving effects last for several months after the injections.

If the injections are successful, a doctor may repeat the procedure after about 6 months.

Side effects

According to the American College of Rheumatology (ACR), the most common side effects of HA injections into the knee are localized pain, warmth, swelling, and difficulty moving the knee. These side effects are usually temporary.

Other common side effects, according to the ACR, include:

Plasma-rich platelet injections

Plasma-rich platelet (PRP) therapy is a process that involves injecting the person’s own blood platelets into the knee joint. This releases growth factors that may stimulate cells involved in tissue repair.

Some people have tried platelet-rich plasma injections for OA. However, both the ACR and the Arthritis Foundation advise against using these treatments.

There is no standard procedure for either approach, and a person will not know what exactly is in their injection. Also, there is not enough evidence to show that these options are safe or effective.

Knee injections can provide fast and effective relief from knee pain and inflammation, but the effects are only temporary.

As OA progresses, a person may experience a decline in mobility and quality of life. At this point, a doctor may recommend knee replacement surgery, or “knee arthroplasty.”

There are two main types of knee replacement surgery — total knee replacement and partial knee resurfacing.

Total knee replacement

A total knee replacement involves removing the worn-out cartilage of the knee and capping it with metal and high-grade plastic.

The prosthesis allows the individual bones of the knee joint to slide over each other smoothly, reducing pain and improving the range of motion in the joint.

The surgery typically takes 1–2 hours. A person may then need to stay in hospital for 1–3 days while they recover from the surgery.

Partial knee resurfacing

Partial knee resurfacing involves removing and replacing only the damaged surface of the knee joint and leaving any healthy cartilage intact.

Doctors may recommend this procedure for people who have disease or damage to only one area of the knee.

Because a partial knee replacement preserves healthy bone, cartilage, and ligaments, it may feel more natural than a total knee replacement.

Compared with a total knee replacement, a partial knee replacement involves a smaller surgical incision. As such, OrthoInfo associates it with the following benefits:

  • faster recovery time
  • less pain following surgery
  • reduced risk of infection and blood clots

When faced with the option of surgery, some people may wonder which is the most effective method — total knee replacement or partial knee resurfacing.

The below table compares the pros and cons of both procedures.

Partial knee resurfacing Total knee replacement
Doctors may recommend if OA is in just one of three knee compartments.Doctors may recommend if OA has progressed and affects mobility and quality of life.
May last up to 10 years, after which a person may need revision surgery.May last up to 20 years.
Faster recovery time, lower risk of infection, and less pain following surgery. Surgery typically lasts 1–2 hours and may require a stay in hospital for 1–3 days.
May feel more natural than a total knee replacement. Involves inserting a prosthesis made of metal and plastic.
A person may feel more residual anterior knee pain, or frontal knee pain, after the procedure.May allow someone to resume normal activities if other nonsurgical options are no longer helpful.

A 2020 randomized controlled trial analyzed findings from 528 patients who either had total knee replacement or partial knee resurfacing. Researchers collected follow-up data for 5 years after the surgery.

They found that both surgery methods were effective, and both had similar clinical outcomes. They also found that both methods had similar reoperation and complication rates.

However, the study found that partial knee resurfacing had significantly higher rates of patient approval than total knee replacement in some cases. This may mean that patients were generally more satisfied with the results of partial knee resurfacing.

Researchers also found that partial knee resurfacing was more cost-effective than total knee replacement after 5 years.

As with other types of surgery, knee replacement surgery is associated with the following risks:

However, people should be aware that delaying knee replacement surgery may lead to further deterioration of the knee joint. This presents other risks, such as:

  • an increased risk of abnormalities developing inside and outside the joint
  • an increased risk of muscles, ligaments, and other structures becoming weak and losing function
  • increased pain or an inability to manage pain
  • increased disability or lack of mobility
  • difficulty with normal daily activities

Before electing to have knee replacement surgery, a person should speak with a doctor about the potential risks and benefits of the procedure.

The following home remedies may help to alleviate knee pain in some cases:

  • Avoid putting weight on the knee: A person should rest the knee as much as possible and avoid standing for long periods of time.
  • Apply a cold compress: A person can try applying an ice pack to their knee to help relieve the pain. It is important to wrap the ice in a cloth or towel first. Applying ice directly to the skin can result in permanent injury.
  • Take over-the-counter pain relief: Acetaminophen can help to alleviate knee pain, while nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen can help to reduce both pain and inflammation.
  • Exercise: Light, low-impact exercise, such as exercising on a stationary bike, may be beneficial for the knees.
  • Avoid stairs: Using stairs may worsen pain in the knee.

There are several different treatment options for a person living with OA of the knee. Nonsurgical methods include knee injections. There are several different options for knee injections, including corticosteroid injections and viscosupplementation.

These options have side effects and complications, such as swelling and possible joint infections. However, they may help relieve pain and improve mobility.

If these options do not work, a doctor may recommend surgery. The two types of surgery for knee OA are partial knee resurfacing or total knee replacement. Surgery can also pose risks and complications, such as infection or nerve damage.

A 2020 study found that partial knee resurfacing had higher rates of patient approval than total knee replacement and that partial knee replacement was more cost-effective after 5 years.