Facet joint injection

Facet (zygapophyseal) joint injections are performed primarily for the diagnosis and differentiation of facet syndrome and radicular pain syndrome, and are one of the spinal interventional procedures. They can be performed under fluoroscopic, or CT image guidance, and cervical, thoracic or most commonly lumbosacral facet joints can be injected, and one or multiple joints can be injected during one procedure. 

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

• young age

• steroid injection in same/other joint

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

Cervical posterior/ thoracic/ lumbosacral

• prone position

Cervical lateral

• lateral, targetted side facing up 

Equipment

• sterile dressing pack; sterile gown and gloves

• skin marker

• metal rod (fluoroscopy), biopsy grid (CT)

• 10 mL syringe, hypodermic needle (25G) and local anaesthetic (e.g. lignocaine) for subcutaneous infiltration

• spinal/ quincke needle (i.e. 25G 51mm cervical, 22 G 90mm lumbosacral) 

• 3 mL syringe, steroid (e.g. betamethasone, triamcinolone ), long-acting local anaesthetic (e.g. ropivacaine, bupivacaine) for intra-articular injection

• 5 mL syringe, iodinated contrast (debated as periarticular injections seem to have the same result as intra-articular injections)

• connecting tubing

• 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: cervical lateral

• consent, check for allergies

• patient lateral, with target side up, a pillow under their head, and to consider a pillow between knees for comfort

• optimise fluoroscopy images, using all planes, until the targeted facet is perpendicular to the x-ray beam (will often see a crisp air gap)

• the target point is the central point of the facet joint and once identified, mark the skin entry point(s) using fluoroscopy and a metal rod ⁴

• clean skin and draw up medications

• local anaesthesia to skin

• use a Quincke needle (i.e. 25G 50mm needle depending on neck size) and fluoroscopic guidance to cannulate facet joint, using an eye of the needle approach

• confirm an intra-articular needle position with a small amount of iodinated contrast through the connecting tubing

• save images with needles in situ

• give the steroid and local anaesthetic injectate

• remove needle and repeat if other facets on the ipsilateral side are to be injected

• turn patient over and repeat if contralateral (bilateral) injections are being performed

Fluoroscopic-guided: cervical posterior

• consent, check for allergies

• patient lying prone with either a pillow under their forehead or leaning on forearms, and consider a pillow under ankles for comfort

• optimise fluoroscopy images, including the collimation and magnification

• the target point is the most inferior portion the facet joint, usually at the same level as the disc, projected over the lateral 1/4 of the vertebral body ⁴

• mark the skin entry point(s) using fluoroscopy and a metal rod

• clean skin and draw up medications

• local anaesthesia to skin

• use a Quincke needle (i.e. 25G 40mm needle depending on neck size) and fluoroscopic guidance to cannulate facet joint, using an eye of the needle approach

• confirm an intra-articular position needle position with a small amount of contrast through connecting tubing

• save images with needles in situ

• give steroid and local anaesthetic injectate

• remove needle and repeat if bilateral/other level facet joint injections are being performed

Fluoroscopic-guided: lumbar posterior

• consent, check for allergies

• time out

• patient prone, and consider pillow under ankles for comfort

• optimise fluoroscopy images, including collimation and magnification

• the target is inferior recess of the facet joint, projected over the lateral 1/3 of the vertebral body ⁴

• mark the skin entry point(s) with fluoroscopy and a metal rod

• clean skin and draw up medications

• local anaesthesia to skin

• using a Quincke needle (i.e. 22G 90mm needle) under fluoroscopic guidance target the facet, using an eye of the needle approach, the needle parallel to the x-ray beam

• consider confirming an intra-articular position with a small amount of contrast through connecting tubing

• save images with needle in situ 

• give steroid and local anaesthetic injectate

• repeat for other facet joints as indicated

CT-guided

• time out

• patient prone, targeted planning scan with overlying biopsy grid 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

• repeat for other facet joints as indicated

Post-procedure care

• pain score assessed immediately and 15-20 minutes post-procedure

• observe for 20 minutes for any immediate complications

• advise to complete pain diary for the next two weeks

Complications

Complications are rare ^{2, 3}:

• infection, including septic arthritis and discitis-osteomyelitis

• allergic/anaphylactic reaction

• local reaction to steroid injection (usually >48 hours)

• bleeding 

Outcomes

Although early studies reported reasonable long term relief of symptoms (20-54%), 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.

Practical points

• even with the use of local anaesthetic, facet joint injections can be sore and the patient should be advised this before starting the procedure

• many institutions now only will perform diagnostic facet joint injections, with the view to perform further treatment with a medial branch block(s)