Injection therapy involves using a needle and syringe to relieve pain by injecting medication into a patient's joints, soft tissues or other areas. It typically is used only when less invasive forms of treatment fail to relieve symptoms.

Types of injection therapy include:

• Facet joint injections. Anesthetics or corticosteroids are injected into the facet joints, which are located between the vertebrae.
  
  
• Nerve root blocks. Anesthetics or corticosteroids are injected into a portion of a nerve that is inflamed or compressed.
  
  
• Viscosupplementation. A lubricant called hyaluronate is injected into a joint afflicted by osteoarthritis.
  
  
• Prolotherapy. A sugar solution or other irritating substance is injected into trigger points (areas where pain is felt) in the fibrous tissue that covers bones. This is believed to trigger inflammation, which causes fibrous tissue growth that can strengthen the area.
  
  
• Trigger point injections. Anesthetic is injected directly into areas of the body where pain is present.

Examples of conditions that may be treated with injection therapy include carpal tunnel syndrome, sciatica, arthritis, bursitis, tendinitis and tennis elbow.

In most cases, injection therapy is an outpatient procedure using a local anesthetic. A fluoroscopic x-ray may be performed to help the physician guide the needle to the right spot. Patients often are able to resume their daily activities within a brief period of time following the procedure.

Injection therapy is usually a safe procedure. However, side effects sometimes occur, such pain, bleeding, infection or nerve damage.

Controversy remains over the effectiveness of injection therapy. Though some experts recommend them, studies have not conclusively shown injection therapy to be effective in treating certain types of pain.