Knee Joint Injections
Because the knee joint supports our body weight through several types of movement (bending, flexing, and twisting), it is prone to traumatic injury. Knee joint injections are a minimally-invasive way to help ease your pain and restore the knee’s range of motion. They deliver relief from pain and inflammation directly into the affected area of your knee. Here’s what you should know.
What are knee joint injections?
Your knee is a complicated joint that is intricately designed to bear weight and enable movement. The knee’s anatomy makes it both strong and vulnerable to injury at the same time.
The knee is made up of bones, muscles, and connective tissues. The femur, fibula, tibia, and patella are the four bones of the knee. The quadriceps is the muscle that supports the front of the knee, while hamstrings provide support behind the knee.
The joint is further stabilized by ligaments and cartilage including:
- The anterior cruciate ligament (ACL) that keeps the femur from putting pressure on the tibia
- The posterior cruciate ligament (PCL) that inhibits the femur from sliding forward
- Collateral ligaments (medial and lateral) which support the knee joint
- The meniscus (lateral and medial) that provides a cushion between the tibia and the femur
- Articular cartilage that cushions the patella
Fluid in the knee joint provides lubrication and enables ease of movement. Bursae are fluid-filled sacs that cushion the spaces between structures in the joint.
Injury to any of these structures of the knee can be very disruptive, impairing the ability to perform daily activities. Knee injections are used to treat certain types of knee pain and inflammation involving ligaments, tendons, and cartilage. You can see an overview of this procedure in the following video.
Types of knee joint injections
The type of knee joint injection you receive depends upon the nature of your knee injury.
Common ones include:
- Corticosteroid injections
- Hyaluronic injections
- Nerve blocks
Corticosteroid injections help to reduce pain and inflammation due to injury or chronic disease. On the other hand, to lubricate the joint and control the pain of osteoarthritis, hyaluronic injections are a good choice.
Finally, nerve blocks, most commonly a saphenous block, can be especially helpful to patients who have been treated with a knee replacement and have lingering knee pain.
What conditions can a knee joint injection help with?
The most common conditions that knee joint injections help treat are chronic arthritis and acute injury in the joint. These injections are minimally-invasive and performed in an outpatient setting, providing an alternative to surgery. They can help:
- Decrease pain by inhibiting the transmission of pain messages
- Promote healing
- Improve quality of life in patients with limited mobility
- Treat inflammation
- Lubricate the joint
Overall, pain relief from knee injections can allow you to be more mobile and engage in an active, healthy lifestyle. They’re best done in concert with other treatments like physical therapy.
Knee pain occurs most often due to the simple wear and tear of this hardworking joint as we age. The Centers for Disease Control and Prevention reports 50% of adults over the age of 65 suffer from arthritis (and approximately 26% of the U.S. regardless of age).
Of the 100 forms of arthritis, osteoarthritis is the most common, causing inflammation and degradation of knee cartilage over a lifetime of use.
When it comes to injury, tendinitis (an acute or chronic inflammation of the knee joint) often causes knee pain due to a tendon injury that occurs after a twisting motion. The meniscus, a pad of cartilage cushioning the bones of your knee joint, is also susceptible to injury.
If you have damage to the musculoskeletal tissues of the knee and your pain has not responded to more conservative knee pain treatments such as physical therapy, over-the-counter pain relievers, hot and cold application, or rest, you may find relief of pain through knee injections (or a combination of approaches).
An overview of the knee joint injection procedure
Most often, knee injections are a minimally-invasive procedure performed in a doctor’s office or clinic as an outpatient procedure.
To begin, you take a comfortable position that gives your doctor easy access to the injection site. The injection site is cleaned with antiseptic. Your doctor will use a local anesthetic to numb the area.
If there is fluid present that may interfere with the injection, your doctor may remove that fluid first. Once the area is comfortably numb, they’ll insert a needle into the joint to drain excess fluid. This removal of fluid often results in immediate pain relief since it reduces pressure within the joint.
Next, your doctor will insert another needle into the knee joint. They’ll inject the medication, along with a local anesthetic to provide immediate pain relief. One medication works for immediate relief, while the other medication works on long-term pain relief. During the procedure, your doctor may opt to use digital imaging to guide the needle to the proper location.
From start to finish, the entire procedure usually takes less than an hour.
Although knee joint injections are generally safe, there are risks any time the skin is broken.
These side effects and risks can include:
- Damage to tissues or nerves
Additionally, each type of knee injection carries its own set of specific risks. Some osteoarthritis injections may include processed chicken or rooster combs, and patients with an allergy to eggs or poultry are at risk for an allergic reaction. Sometimes, hyaluronic injections may cause a pseudo-septic reaction in the knee joint that shows up as pain, swelling, and redness.
Corticosteroids are useful in treating pain but carry a serious risk for both local and systemic side effects. In particular, repeated, long-term use of steroid injections poses a risk of cartilage or ligament damage. There is also the possibility that the corticosteroid will crystallize in the joint and worsen inflammation.
Systemic side effects of steroids include:
- Osteoporosis (bone loss)
- Increased blood pressure
- Elevated blood sugar levels
- Degenerative eye disease, such as cataracts and glaucoma
- Weight gain
- Depressed immune function, which increases risk of infection
- Ulcers and bleeding in the gastrointestinal tract
It is important to discuss all of the risks and benefits of knee joint injections with your doctor. Because of risks with long-term use, most doctors will suggest a course of only a few injections per year, at most.
Knee joint injection recovery is usually simple and quick. You can go home after this outpatient procedure, and most people resume normal activity after just one day of rest. Pain relief may be gradual or it may be profound and nearly instant. This will depend on the condition being treated and the injection you receive.
For minor pain and swelling at the injection site, ice and over-the-counter medications can help. Call your doctor if:
- Pain and swelling increases
- You experience fever
- There is blood or other discharge at the injection site
These can be a sign of infection.
Could a knee joint injection help me?
Knee injection treatment success depends on the severity of damage. You may require only a one-time injections or a series of injections to find pain relief.
In cases of osteoarthritis, patients usually report decreased pain sensation after four to 12 weeks of treatment. Pain relief may last for months, and repeat treatments may be given as needed.
These injections are best combined with a treatment like physical therapy. During lower pain periods, you can undergo therapy to resolve the underlying cause of your pain. This may include muscle strengthening or working through tightness or imbalances in the body. Together, they can help you work towards a life with less pain.
- Arizona Pain. Expert Guest Dr. Anikar Chhabra. Retrieved from https://arizonapain.com/patient-information/arizona-pain-monthly/august/expert-guest/
- Lisa Pavese, FNP, Tory McJunkin, MD, and Paul Lynch, MD. Knee Pain Treatment. Retrieved from https://arizonapain.com/pain-center/#conditions/knee-pain/
- Melinda Ratini, Do, MS. (May 23, 2012). Hyaluronan Injections for Knee Osteoarthritis. Retrieved from http://www.webmd.com/osteoarthritis/guide/hyaluronan-injections-knee
- David Zelman, MD. (May 10, 2012). Corticosteroid Injections for Osteoarthritis. Retrieved from http://www.webmd.com/osteoarthritis/guide/corticosteroid-injections-for-osteoarthritis