Knee Injections: Types, Procedure, Risks, and Recovery

How to Give an Injection in the Knee?

Giving an injection in the knee is a precise medical procedure performed exclusively by qualified healthcare professionals, such as orthopedic surgeons, rheumatologists, or sports medicine physicians. It is never to be attempted by individuals without proper medical training and licensure due to the significant risks involved.

The Role of Knee Injections in Orthopedic Care

What are Knee Injections? Knee injections involve the administration of various therapeutic substances directly into the knee joint (intra-articular) or surrounding soft tissues. The primary goal is to deliver medication to the site of inflammation, pain, or degeneration, providing targeted relief and often facilitating rehabilitation.

Common Indications: Knee injections are frequently utilized to manage conditions such as:

• Osteoarthritis (OA): To reduce pain and inflammation, or improve joint lubrication.
• Rheumatoid Arthritis (RA) and other inflammatory arthropathies: To control inflammation within the joint.
• Bursitis: Inflammation of the bursae around the knee.
• Tendinitis: Inflammation of tendons, such as patellar tendinitis or quadriceps tendinitis.
• Post-traumatic inflammation: Following injuries that cause significant joint swelling.

Who Administers Knee Injections?

Qualified Healthcare Professionals: Knee injections are complex medical procedures requiring a deep understanding of anatomy, sterile technique, and potential complications. They are performed by:

• Orthopedic Surgeons: Specialists in musculoskeletal conditions.
• Rheumatologists: Specialists in inflammatory joint diseases.
• Sports Medicine Physicians: Specialists in injuries and conditions related to physical activity.
• Physiatrists (Physical Medicine and Rehabilitation Physicians): Specialists in restoring function.
• Physician Assistants (PAs) and Nurse Practitioners (NPs): Under the supervision of a physician and within their scope of practice.

Why Professional Administration is Crucial: Attempting a knee injection without proper training carries severe risks, including:

• Infection: Introducing bacteria into the joint can lead to septic arthritis, a medical emergency that can cause permanent joint damage.
• Nerve Damage: Accidental injection into or near nerves can cause pain, numbness, or weakness.
• Tendon/Ligament Damage: Direct trauma from the needle or certain medications (like corticosteroids) can weaken or rupture tendons/ligaments.
• Improper Placement: Injecting outside the joint space renders the medication ineffective and can cause local tissue damage.
• Bleeding/Hematoma: Puncturing blood vessels can lead to significant bruising and swelling.

Types of Substances Injected into the Knee

Healthcare professionals select the appropriate substance based on the patient's diagnosis and overall treatment plan.

• Corticosteroids (e.g., Cortisone):

  • Mechanism: Potent anti-inflammatory agents that reduce pain and swelling.
  • Uses: Primarily for acute inflammatory conditions like osteoarthritis flares, rheumatoid arthritis, bursitis, or tendinitis.
  • Considerations: Effects are typically temporary (weeks to months). Repeated injections are generally limited due to potential side effects like cartilage damage or tendon weakening.

• Hyaluronic Acid (HA) / Viscosupplementation:

  • Mechanism: Hyaluronic acid is a natural component of synovial fluid, acting as a lubricant and shock absorber in the joint. Injections aim to supplement the joint's natural fluid.
  • Uses: Primarily for osteoarthritis, especially when other treatments haven't provided sufficient relief.
  • Considerations: Usually administered as a series of 1-5 injections over several weeks. Effects may take longer to manifest but can last for several months.

• Platelet-Rich Plasma (PRP):

  • Mechanism: Derived from the patient's own blood, PRP contains concentrated growth factors that are believed to promote healing and reduce inflammation.
  • Uses: Emerging treatment for osteoarthritis, tendinopathies, and ligament injuries.
  • Considerations: Still considered experimental for some indications, and efficacy varies. Requires a blood draw and specialized processing.

• Prolotherapy / Dextrose Injections:

  • Mechanism: Involves injecting a mild irritant (often dextrose solution) into ligaments or tendons to stimulate a healing response and strengthen weakened tissues.
  • Uses: For chronic pain due to ligamentous laxity or tendinopathy.
  • Considerations: Often involves multiple injections over time.

The Procedure: What to Expect During a Knee Injection

While you won't be performing the injection, understanding the steps involved can help you prepare as a patient.

• Patient Preparation: You will typically lie down on an examination table with your knee exposed and positioned to allow optimal access to the joint.
• Skin Sterilization: The healthcare professional will thoroughly clean the skin around the injection site with an antiseptic solution (e.g., iodine or chlorhexidine) to minimize the risk of infection. This is a critical step.
• Local Anesthesia (Optional but Common): A local anesthetic (e.g., lidocaine) may be injected into the skin and underlying tissues to numb the area, making the procedure more comfortable.
• Anatomical Landmarks and Precision: The professional uses anatomical landmarks to guide the needle. In many cases, especially for intra-articular injections, imaging guidance (ultrasound or fluoroscopy/X-ray) is used to ensure precise needle placement within the joint space and avoid vital structures. This significantly increases safety and efficacy.
• Needle Insertion and Aspiration: A thin needle is carefully inserted into the target area (e.g., joint space, bursa, or tendon sheath). Before injecting the medication, the professional may aspirate (pull back on the syringe plunger) to ensure no blood vessels have been entered. If blood is aspirated, the needle position is adjusted.
• Medication Delivery: Once proper placement is confirmed, the medication is slowly injected. You might feel a sensation of pressure or fullness in the joint.
• Needle Withdrawal and Post-Injection Care: The needle is quickly withdrawn, and pressure is applied to the injection site with a sterile dressing or cotton ball to prevent bleeding. A small bandage is then applied.

Potential Risks and Complications

While generally safe when performed by a professional, knee injections carry potential risks:

• Common Side Effects:
  • Temporary pain or soreness at the injection site.
  • Swelling or bruising.
  • A temporary "flare" of pain after corticosteroid injections (post-injection flare), which usually subsides within 24-48 hours.
• Less Common but More Serious Complications:
  • Infection: The most serious complication, requiring immediate medical attention. Signs include increasing pain, redness, swelling, warmth, and fever.
  • Allergic Reaction: To the medication or local anesthetic.
  • Nerve Damage: Leading to numbness, tingling, or weakness.
  • Tendon or Ligament Weakening/Rupture: Primarily a risk with repeated corticosteroid injections into or around tendons.
  • Skin Discoloration or Fat Atrophy: Localized changes at the injection site, particularly with corticosteroids.
  • Elevated Blood Sugar: Especially in diabetic patients receiving corticosteroids.

Importance of Discussing Risks with Your Doctor: Before any injection, your healthcare provider will discuss the potential benefits, risks, and alternative treatments, ensuring you provide informed consent.

After the Injection: Recovery and Follow-Up

• Activity Restrictions: You may be advised to limit strenuous activity for 24-48 hours after the injection, depending on the substance injected and your specific condition.
• Monitoring for Side Effects: Keep the injection site clean and dry. Monitor for any signs of infection or other unusual symptoms.
• Pain Management: Over-the-counter pain relievers (e.g., acetaminophen or NSAIDs like ibuprofen, if not contraindicated) and ice packs can help manage any post-injection discomfort.
• Rehabilitation and Physical Therapy: Injections are often part of a broader treatment plan. Your doctor may recommend physical therapy, exercise, or lifestyle modifications to maximize the long-term benefits and address the underlying cause of your knee pain.

Conclusion and Important Disclaimer

Knee injections are valuable tools in the management of various knee conditions, offering targeted relief from pain and inflammation. However, they are complex medical procedures that demand the expertise of qualified healthcare professionals. This information is intended for educational purposes only to help you understand the process and risks involved when a medical professional performs the procedure.

Always consult a licensed healthcare professional for any medical advice, diagnosis, or treatment. Do not attempt to self-administer knee injections.