Problem facts
-Diagnosing facet joint arthropathy as pain generator
-Traumatic/degenerative/inflammatory
-36% in young adults, >89% in >70yo (have changes)
-Indication – axial spine pain poorly controlled or unexplained
-Physical and neurological findings are not conclusive
-Imaging findings are not conclusive (inc SPECT)
-Facet takes 25% of axial and 40-65% of rotational forces
-RFs – Age, obesity, body mechanics, overuse, microtrauma
-Often associated with disc degeneration
-C2-3 if associated with headache
-L4-5, L5/S1 most common
Palpation shows tender transverse and paravertebral
Diagnosis
-Pain localised over back in non-dermatomal radiation pattern
-Back of buttock and thighs (rare below the knee)
-Neurology is unlikely as primary generator
-Though can have associated osteophytes/cysts
-Palpation shows tender transverse and paravertebral
-Pain exacerbated by extension and rotation
-Kemp test (Sens <50% and Spec <66%)
Imaging
-Plain film sensitivity and specificity is poor (even oblique views)
-MRI can show degen changes (>90% Sens/spec)
-CT better for bony margins though
Evidence
-Diagnostic block of facet joint has level 1 or level 2 on USPTF criteria
-Successful diagnostic block if >80% of pain relief post injection
-Can have false positive rate (due to local other structures)
-Though double diagnostic rarely performed
Complications
-Rare
-Case reports of infection
-Dural puncture
-Spinal anaesthesia
-Neuritis (5%)
-Transient numbness or dysaesthesias
Key anatomy to know:
-Superior articular process
-Transverse process
-Inferior articular process
-Spinous process
-Dorsal root ganglion
-Medial and lateral branch of
Procedural equipment
- Local anaesthetic
- Needles
- C-Arm
Procedural steps:
-Confirm the target level (AP view)
-Line up vertebral superior end plate of target
-Oblique the C-arm ipsilateral for Scotty Dog appearance ?Angle
-L1-L4 target is junction of SAP and TP – where nerve is midway between superior border of TP and the MAL notch (just superior to the eye of the Scotty dog)
-L5 target is dorsal ramus not MB. Goes over Ala of sacrum
-Iliac crest may block trajectory – 10deg less oblique required
-Target middle of base of SAP
Procedural steps tips:
-Caudally positioned bevel may reduce epidural spread
-0.3 ml of contrast
-0.5 ml of local anaesthetic
Outcomes
Follow up
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