Several types of injections are used to relieve knee pain symptoms, such as steroid injections, hyaluronic acid (HA), platelet-rich plasma (PRP), and regenerative therapies.
Knee injections for pain can be a practical option for people who do not respond to pain management drugs and for people who want to treat knee pain without surgery. The injections can temporarily relieve symptoms and improve pain and joint function. A healthcare provider will give these injections directly into the affected joint.
1. Steroid Injections
Steroid injections, also known as corticosteroid injections, are anti-inflammatory drugs used to treat various conditions. They are often prescribed for people withrheumatoid arthritis and other types of inflammatory arthritis causing joint pain, warmth, tenderness, and swelling. They are also used inosteoarthritis (joint pain and stiffness that comes on with age and wear and tear) for extra pain relief.
The steroid injections work similarly to the natural steroid hormones released by adrenal glands (small glands located above the kidneys) in the body.
Wheninjected locally into a joint or muscle, steroids relieve pain, stiffness, and swelling (inflammation) in the nearby area.
Common examples include:
- Aristospan (triamcinolone)
- Hydrocortisone
- Medrol (methylprednisolone)
While useful for short-term pain relief, studies have not shown corticosteroid injections to be beneficial for long-term management. One study indicated that repeated injections may have destructive effects on cartilage, with no long-term benefit for knee pain.
What to Expect
Steroid injections areonly given by healthcare providers in a healthcare setting (hospital or clinic).
Your provider inserts a small needle to inject medicine into the specified area. Depending on the injection site, the healthcare provider may use an X-ray or ultrasound to see the inflamed area.
A steroid injection mayalso containa local anesthetic (a numbing drug) to reduce the discomfort while injecting the drug.
You can go home the day of the procedure. If you have swelling after the injection, apply an ice pack over the site for 15 to 20 minutes a few times a day. Get plenty of rest for a few days after getting a shot.
Steroidinjectionstypically take five to seven daysto start working to reduce pain and inflammation. The effects usually last a few weeks or up to three months.
Some common risks associated with steroid injections include:
- Allergic reaction to the medicine
- Damage to nerves near the joint or soft tissue
- Increased blood sugar levels for several days after the injection (for people with diabetes)
- Infection
- Injection site reaction (pain, swelling and bruising, or discoloration of skin at the site of the injection)
It is important to note that steroid drugs are not artificial steroids used to develop muscle mass.
How Long Do Cortisone Shots Last?
Corticosteroid injections can help reduce pain for up to three months after the injection. However, results may vary among people.
2. Knee-Gel Injections (Hyaluronic Acid)
Knee-gel injections are hyaluronic acid injections. They can be used to treat arthritis if other treatments haven’t worked first. However, they are not a first-line treatment for arthritis and are not recommended by the American Academy of Orthopaedic Surgeons and other organizations.
In arthritis, synovial fluid is increased and cartilage (connective tissue in joints) is reduced, causing inflammation and pain. Hyaluronic acid is a natural substance present in the synovial fluid of your knee joints. It works to lubricate the joint and absorb shocks during movements. It also increases synovial fluid viscosity and decreases the degradation of cartilage.
Your healthcare provider may inject hyaluronic acid into the joint to help increase lubrication and reduce pain. Hyaluronic acid is also called artificial joint fluid or viscosupplementation.
What to Expect
When administering hyaluronic acid, the healthcare provider will do the following:
- Inject local anesthesia into the space around the joint to numb it.
- If required, drain excessive fluid that is causing swelling of the joint.
- Inject hyaluronic acid into the joint.
Some common side effects associated with hyaluronic acid injections are pain and swelling in the joint. Some people may have a more severe reaction called an injection flare. It causes fluid accumulation with pain and swelling in the joint.
You may need an injection every week for three to five weeks to start feeling the improvement in symptoms. The pain relief can last a few months, but this may vary. In some people, the benefits of knee-gel injections last for six months.
Knee-gel injections are a low-risk treatment option. It can help manage your symptoms for longer without needing surgery.
Why Is My Knee Pain Worse After a Gel Injection?
It's normal to feel a bit of soreness or stiffness for a few days following the injection. However, in some cases, a severe localized reaction can occur. This can cause severe pain and swelling in the injected joint. It can happen anywhere from a few hours after the injection to five or six days later.
Contact your provider if you have severe pain or swelling after receiving an injection.
3. Prolotherapy Injections
Prolotherapy is a regenerative medicine treatment used to relieve pain. It is an injection of an irritant solution (usually a dextrose sugar or saline) given in joints, ligaments, or tendons.
Experts suggest that prolotherapy may relieve pain by increasing the body's natural healing abilities. A local inflammatory response is initiated to trigger the release of growth factors and collagen.
Prolotherapy is an alternative treatment not regulated by the Food and Drug Administration (FDA). The American College of Rheumatology also does not recommend this treatment for knee or hip osteoarthritis.
However, some research supports its effectiveness in reducing stiffness and pain in various musculoskeletal conditions. The effectiveness of prolotherapy is not universally accepted because of incomplete research.
Prolotherapy does not cure any condition and is used as an elective (nonurgent) treatment.
What to Expect
Prolotherapy treatment generally involves three to four injections or more given over several months. The healthcare provider injects an irritant solution into a joint or ligament. You can go home immediately after the procedure.
Prolotherapy is a relatively low-risk treatment that usually doesn't have any severe side effects. The most common side effect is soreness and swelling at the injection site. Other risks may include:
- Allergic reactions
- Bruising
- Headaches
- Nerve irritation
- Temporary numbness
What Is the Success Rate of Prolotherapy Injections?
Prolotherapy is not recommended as a first-line treatment due to the lack of evidence. Since most studies evaluating prolotherapy have only tracked its effects over several months, it's difficult to say how beneficial it may be in the long term. Larger and longer clinical trials are necessary to determine the extent of its success in people with osteoarthritis.
4. Platelet-Rich Plasma Injections
The platelet-rich plasma (PRP) technique uses a person's own blood cells to accelerate healing in a specific area. PRP injections can treat a range of musculoskeletal conditions. They are also used in cosmetic procedures. These injections can help reduce pain and inflammation, particularly in people in the early stages of arthritis.
PRP injection consists of plasma (the liquid portion of blood) and platelets (a type of blood cell).
The mechanism behind PRP injections is not completely understood. However, studies show that the increased concentration of growth factors (natural proteins or hormones) in platelet-rich plasma may stimulate or speed up the healing process.
What to Expect
A healthcare provider injects the PRP solution into a knee or a tendon. Sometimes, the provider uses an ultrasound to guide the injection.
The results of PRP treatment are noticeable after several weeks and up to 12 to 24 months after the injection. Some people may need additional injections as recommended. PRP injections do not usually cause any severe side effects.
5. Stem Cell Injections
Stem cells are regenerative medicine obtained from the following:
- Amniotic fluid
- Blood
- Bone marrow
- Muscle
- Umbilical cord
Stem cells are undifferentiated cells that can increase in number or turn into almost any other type of human cell.
Mesenchymal stem cells (MSCs) are emerging as a potential treatment option for osteoarthritis. Stem cell treatments help regrow cartilage, which is lost in osteoarthritis. The cells travel to injury sites or inflamed body parts to release several natural regenerative and growth factors.
Stem cells can enhance the growth of cartilage and supporting tissue, thus improving tissue repair. They can also decrease the intensity of inflammation and prevent a hyperactive immune response.
The FDA does not approve stem cell therapy to treat arthritis. More research and trials are needed to prove the efficacy of this procedure.
Does Insurance Cover Stem Cell Injections for Knee Pain?
The FDA has not approved stem cell therapy for osteoarthritis. It is considered an investigational therapy. The treatment still needs to be standardized, and most insurance companies do not cover the cost of the therapy.
Injections for Pain: When Should You Use Them?
The first line of treatment to manage the symptoms of osteoarthritis is a combination of medications with nondrug methods. Nondrug methods may include:
- Healthy weight maintenance
- Low-impact exercise, such as walking, water exercise, or yoga
- Physical therapy
- Supportive pain management, such as using heat and ice
OTC painkillers and anti-inflammatory drugs such as topical gels, nonsteroidal anti-inflammatory drugs (NSAIDs) such as OTC Advil or Motrin (ibuprofen), or prescription drugs such as opioids and steroids relieve pain and reduce disability.
People with hip and knee osteoarthritis who do not respond to these drugs are prescribed knee injections. When all other oral medications do not give the required results, knee injections are usually a treatment of choice before resorting to surgery.
Summary
Different types of injections are available to help reduce arthritis symptoms, such as pain and inflammation, and slow the progression of joint destruction.
While OTC and prescription pain relievers are considered first-line therapy, several novel therapeutic strategies are being investigated and developed for knee pain. These injectables can improve the lubrication between the joints to ease the symptoms.
Steroids, hyaluronic acid injections, and regenerative therapies, such as PRP and stem cell injections, are among the available options. Based on the current evidence, steroid injections are the most widely accepted of the injection therapies for short-term pain relief.