Cervical Facet Arthropathy

Definition: Pain arising from the cervical zygapophysial (facet) joints, typically axial and non-radicular. Diagnosis is made by response to controlled medial branch blocks, not by imaging.

Epidemiology

• Most common identifiable source of chronic neck pain after whiplash (around 60% of cases; Lord 1996).
• C2/3 and C5/6 are the most frequently involved levels.
• Female predominance; onset often delayed 24-48 hours after a motor-vehicle deceleration injury.
• Neck pain overall is a leading global cause of years lived with disability.

Why it matters: Degenerative facet change on imaging is near-universal with age and correlates poorly with pain, so a structured block-based pathway is essential before committing to ablation.

Facet Joint Structure

• Synovial joint.
• Oriented at 45 degrees in the coronal plane.
• Resists anterior translation and rotation.

Innervation (Crucial for RFA)

• Each joint is innervated by the Medial Branch of the dorsal ramus.
• Dual Innervation: Each joint receives branches from the level above and the same level.
  • Example: C4/5 joint is supplied by C4 and C5 medial branches.
  • Exception: C2/3 joint is supplied by the Third Occipital Nerve (TON) and C2 medial branch.

Pain Referral Patterns (Bogduk Maps)

• C2/3: Occiput, Mastoid (Headache).
• C3/4: Upper neck.
• C5/6: Lower neck, Trapezius ridge, Acromion.
• C6/7: Scapula border.

Facet pain is repeatedly framed here as the commonest source of chronic pain after whiplash, and the WAD mnemonic appears above — but the grading examiners expect, the Quebec Task Force classification of Whiplash-Associated Disorders (Spitzer et al, 1995), is worth stating explicitly because it drives triage and prognosis.

• Symptoms such as headache, dizziness, tinnitus, dysphagia, temporomandibular pain and memory disturbance may accompany any grade and are not themselves graded.
• The vast majority of presentations are Grade I to II; Grade IV (fracture/dislocation) mandates immobilisation and the cervical-fracture pathway, not a pain-block pathway.
• The classification matters for selection: facet-mediated pain and the medial-branch-block pathway are relevant to persistent Grade I-II pain, whereas Grade III (true neurological signs) should redirect you to radiculopathy/myelopathy work-up rather than facet blocks.

History

• "Deep, aching, dull" pain.
• Worsened by looking up (hanging washing) or turning head (reverse parking).
• Morning stiffness common.
• History of MVA (Whiplash).

Examination

• Inspection: Normal alignment or mild torticollis.
• ROM: Restricted Extension and Rotation.
• Palpation: Paraspinal Tenderness over the facet line (2cm from midline). Deep pressure reproducing "the pain".
• Neurology: Must be NORMAL.
• Provocative Test: Extension + Rotation to the affected side ("Closing the door" on the facet).

Physical Therapy

• Multimodal: Isometric strengthening, ROM, Scapular stabilization.
• Ergonomics: Workstation setup (monitor height).
• Psychology: CBT for chronic pain.

Medications

• NSAIDs.
• Neuropathic agents (Gabapentin/Pregabalin) - questionable efficacy for pure facet pain.

The viva section above offers "pulsed or thermal RFA of the TON," but only conventional thermal RF is described elsewhere. These are two distinct modalities and the distinction is examinable.

• Conventional thermal RF destroys the medial branch by heat coagulation; it is the modality validated by the Lord NEJM trial and the basis of the durable relief quoted above.
• Pulsed RF exposes the nerve to a rapidly fluctuating electric field while keeping the tissue cool, so it does not coagulate the nerve. It is proposed where a destructive lesion is undesirable, but its evidence for facet-mediated neck pain is weaker than thermal RF.
• Third occipital nerve (TON): TON neurotomy is technically harder (larger, more variable nerve over the C2/3 joint) and thermal lesioning predictably causes temporary cutaneous numbness and transient unsteadiness/ataxia in the treated territory; this side-effect profile is part of why pulsed RF is sometimes considered there, though thermal neurotomy remains the better-evidenced option.

• Post-RFA:
  • Ice packs for sore neck.
  • Resume normal activity immediately.
  • Physio to capitalize on the "Pain-free window".

• Natural History: Recurrent/Relapsing course.
• RFA Efficacy: The Lord 1996 NEJM RCT showed median relief of 263 days (vs 8 days for sham).
• Whiplash: Poorer prognosis if litigation ongoing, high baseline pain, or Catastrophizing.

Global Epidemiology

• Neck pain is among the leading global causes of years lived with disability (Global Burden of Disease).
• After whiplash, cervical facet joints are the most common identifiable pain source (around 60% of chronic cases; C2/3 and C5/6 most frequent).
• Female predominance; recovery is strongly modulated by psychosocial factors and the local compensation environment.

Practice Variation (high- vs limited-resource)

• High-resource settings: fluoroscopy- or CT-guided diagnostic blocks and RFA are routine in pain/spine services.
• Limited-resource settings: image-guided blocks and RFA equipment may be unavailable; care relies on physiotherapy, analgesia and activity modification, with surgical fusion reserved for instability or deformity.
• The major payer/policy divergence is whether controlled blocks are mandated before RFA (SIS/ASRA, NASS) or whether the whole pathway is restricted (NICE).

• Placebo vs comparative blocks: Comparative blocks (two anaesthetics) still carry residual false positives; only placebo-controlled triple blocks fully exclude placebo, but these are impractical in routine care.
• NICE vs interventionalist societies: NICE restricts diagnostic blocks and RFA for non-specific neck pain, citing weak trial evidence, whereas SIS/ASRA/NASS support RFA when strict block-based selection is applied. The conflict largely reflects how patients are selected.
• Imaging-pain mismatch: Degenerative facet changes on CT/MRI correlate poorly with the pain source, so imaging cannot confirm or exclude the diagnosis.
• Durability and repetition: Relief is finite because the medial branch regenerates; the optimal re-treatment interval and long-term effect on adjacent-segment health remain undefined.
• Whiplash chronicity: Cross-jurisdiction differences in chronicity highlight the contribution of psychosocial and compensation factors rather than a purely structural cause.