FAQs on Knee Injections in Colorado

 

Knee injections are used to treat a variety of types of arthritis, including osteoarthritis, gout, and rheumatoid arthritis. The knee joint can be injected in the doctor’s office.

How common is arthritis?

More than 50 million adults in the United States have doctor-diagnosed arthritis. That’s one in five people over the age of 18 years. Osteoarthritis is the most common type of arthritis, and it affects around 30 million Americans.

What are the types of knee injections?

Medications, substances, and solutions injected into the knee include:

  • Hyaluronic acid (HA) supplements – These substances injected into the knee joint are used to replace lost synovial fluid. The HA works much like the synovial fluid, and acts as a shock absorber and lubricant. By replenishing the fluid, the bones move smoothly over each other, and pain resolves. In addition, HA injections help the knee with inflammation. Injecting HA in the joint restores normal viscoelastic properties of the synovial fluid and studies show it has disease-modifying effects. Examples of the product include Orthovisc, Synvisc, and Hyalgan.
  • Corticosteroid – Triamcinolone, dexamethasone, betamethasone acetate, betamethasone sodium phosphate, and methyl-prednisolone are examples of corticosteroid agents used for knee joint inflammation. The injection lasts for up to six months, offering pain relief from cartilage breakdown in the joint. Corticosteroid injections work through an immunosuppressive and anti-inflammatory effect. In addition, they reduce vascular permeability and inhibit the accumulation of inflammatory substances.
  • Platelet-rich plasma (PRP) – This involves drawing the patient’s own blood, processing it by centrifugation in the laboratory, and injecting the concentrated platelets back in the knee joint. PRP contains growth factors that stimulate the body.
  • Arthrocentesis – Joint fluid aspiration is called arthrocentesis. This involves removal of joint fluid that has accumulated inside the joint space of the knee. The doctor often removes excessive fluid before injecting the knee with a corticosteroid, HA, or PRP. Withdrawing fluid will ease swelling and pain.

How is the knee injected?

The pain management specialist can inject the knee in his office. After cleaning the skin with an antiseptic, the doctor uses a fine needle to numb the skin. Once numb, the doctor inserts the procedure needle. Real-time x-ray or ultrasound technology is often used to assure correct needle placement. Once the solution is instilled into the joint space, the needle is removed, and the doctor applies a Band-aid to the injection site.

Do knee injections work?

There is much evidence from randomized controlled clinical trials that support knee injections. In a recent study, corticosteroid injections were found to be superior to placebo for pain control, with results and benefits lasting around 26 weeks. Clinical studies show that HA injections are safe and offer pain reduction for up to 24 weeks. PRP injections work by using insulin-like growth factor, transforming growth factor b-I, cytokines, and chemokines to repair the injured and damaged tissues. In a recent clinical study, PRP injections were used for 115 arthritic knees, with patients having significant improvement at the 6-month and 12-month follow-up visits.

What can I expect after the knee injection?

Your knee will be a little tender after the injection. The full effects are usually not felt right away. Results depend on the type of injection given. This includes:

  • Corticosteroid – Pain relief may be immediate when an anesthetic is added, and the steroid begins to work after 3-5 days.
  • Hyaluronic acid – Most patients notice ease of movement and decreased stiffness immediately. Pain relief is effective after 1-2 days.
  • PRP – Immediately after the injection, the knee joint goes through the inflammatory phase, so expect some tenderness and warmth. Results are noticed after 2-3 weeks.

Resources

Chao J, Wu C, Sun B, Hose MK, Quan A, Hughes TH, Boyle D, Kalunian KC. Inflammatory characteristics on ultrasound predict poorer longterm response to intraarticular corticosteroid injections in knee osteoarthritis. J Rheumatol. 2010;37:650–655.

National Collaborating Centre for Chronic Conditions (UK) Osteoarthritis: National clinical guideline for care and management in adults. London: Royal College of Physicians (UK); 2008

Sánchez M, Anitua E, Azofra J, Aguirre JJ, Andia I. Intra-articular injection of an autologous preparation rich in growth factors for the treatment of knee OA: a retrospective cohort study. Clin Exp Rheumatol. 2008;26:910–913.