Facet joint injection

Facet (zygapophyseal) joint injections are one of the most frequently performed spinal interventional procedures, as both treatment for and diagnosis of radicular pain syndrome and facet syndrome. It can be performed under fluoroscopic, or CT image guidance and cervical, thoracic or most commonly lumbar facet joints can be an injectioninjected. Often the procedure is performed at multiple levels or bilaterally. 

Indications

• facet syndrome: both diagnostic (i.e. relief of pain after injection of local anaesthetic) and therapeutic
• chronic low back or neck pain
• low back pain (+/- sciatica) with normal imaging findings
• post-laminectomy syndrome

Contraindications

There are no specific absolute contraindications, but relative contraindications include ²:

• systemic infection or cutaneous infection over the injection site
• coagulopathy
• contrast reaction or other medication allergies
• pregnancy

Procedure

Preprocedural evaluation

• history of presenting complaint: type, nature, severity, duration and location of back pain
• relevant medical and surgical history
• review relevant laboratory results
• review prior imaging
• counselling patient about onset, length and likelihood of pain relief
• gaining informed consent

Positioning/room set up

• patient is typically in a prone position

Equipment

• sterile dressing pack; sterile gown and gloves
• 10 mL syringe, hypodermic needle and local anaesthetic (e.g. lignocaine) for subcutaneous infiltration
• long spinal needle (typically 22 G), 3 mL syringe, steroid (e.g. betamethasone), long-acting local anaesthetic (e.g. ropivacaine, bupivacaine) for intra-articular injection
• contrast (not always necessary as periarticular injections seem to have the same result as intra-articular injections)
• dressing

Technique

The typical capacity of a facet joint is approximately 2 mL. Injection of large volumes can cause capsular disruption, and discharge of the anaesthetic and steroid mixture into adjacent soft tissues, including the epidural space.

Fluoroscopic-guided

• content required

CT-guided

• time out
• targeted planning scan and skin marking
• sterile preparation and drape
• subcutaneous infiltration of local anaesthetic
• advancement of the spinal needle under CT guidance to the targeted facet joint
• optional intra-articular injection of a small amount of contrast to assess intra-articular position
• injection of 1 mL steroid and 1 mL long-acting local anaesthetic

Post-procedure care

• pain score assessed immediately and 15-20 minutes post procedure
• observe for 20-30 minutes for any immediate complications

Complications

Complications are rare ^{2, 3}:

• infection, including septic arthritis and discitis-osteomyelitis
• allergic/anaphylactic reaction
• local reaction to steroid injection (usually >48 hours)
• transient numbness/paralysis (should resolve in minutes)
• bleeding (e.g. from vertebral artery puncture)

Outcomes

Although early studies reported reasonable long term relief of symptoms (20-54%), more recent studies have suggested that steroid injection "is of little value". However, short term relief is common (59-94%) and therefore it remains a useful procedure, especially to confirm the diagnosis.