High Yield Overview

Cervical Facet Arthropathy

Axial Neck Pain | Diagnosis by Blockade | Radiofrequency Ablation Treatment

55%Chronic Neck Pain Cause

60%Whiplash Prevalence

C2/3Most Common Level

80%Relief Required (MBB)

Diagnostic Criteria (Bogduk)

Pain Pattern

PatternAxial neck pain (No Radiculopathy). Referred patterns to head/shoulder.

TreatmentClinical Suspicion

Block 1

PatternPositive response (greater than 80% relief) to Medial Branch Block

TreatmentScreening

Block 2

PatternPositive response to Confirmatory Block (Different day/agent)

TreatmentConfirmation

Critical Must-Knows

Facet joints (Z-joints) are the most common source of chronic neck pain after whiplash.
Pain is typically AXIAL and NON-RADICULAR (Referral zones exist but do not follow dermatomes).
Degenerative changes on X-ray/CT do NOT correlate well with pain (False positives common).
Diagnosis CANNOT be made by history/exam alone - requires Diagnostic Blocks (MBB).
Treatment of choice for confirmed cases is Radiofrequency Neurotomy (RFA).

Examiner's Pearls

"
C2/3 Facet refers pain to the Occiput (Cervicogenic Headache).
"
C5/6 Facet refers pain to the shoulder/scapula.
"
Pain is worse with Extension and Rotation (Loading the facet).
"
Single block has a high false positive rate (30-40%) - hence double blocking is Gold Standard.

Clinical Imaging

Imaging Gallery

Lateral cervical spine radiograph in extension. Extension loading compresses the facet joints and typically reproduces axial neck pain in facet arthropathy patients - a key diagnostic feature.Credit: Stillwaterising via Wikimedia Commons

Diagnostic Pitfalls

Imaging Fallacy

Treat the patient, not the scan. Severe OA on X-ray does NOT mean the joint is painful. Normal joints CAN be painful (post-whiplash).

Radiculopathy Exclusion

Rule out radiculopathy. If arm pain > neck pain or neuro deficit present, the Nerve Root is the suspect, not the Facet.

False Positive Blocks

Placebo effect is high (30-40%). Sedation invalidates results. A Pain Diary is essential.

At a Glance

Facet Pain vs Discogenic Pain vs Radiculopathy

Feature	Facet Joint (Z-Joint)	Discogenic Pain	Radiculopathy
Primary Pain	Neck (Axial)	Neck (Axial)	Arm (Radicular)
Aggravation	Extension / Rotation	Flexion / Loading	Extension / Spurling's
Referral	Somatic (Head/Scapula)	Somatic (Interscapular)	Dermatomal (Hand)
Deficits	None	None	Motor/Sensory Loss

Mnemonics

Mnemonic

FACETFacet Features

False Positives

High rate on single block

Axial

Pain is axial, not radicular

Cervicogenic

C2/3 causes headache

Extension

Worsens pain

Two Blocks

Required for diagnosis

Memory Hook:Key clinical features.

Mnemonic

SAME + ABOVEInnervation Rule

Same

Medial branch of SAME level

Above

Medial branch of level ABOVE

Memory Hook:Each joint has dual innervation. (e.g. C5/6 joint is supplied by C5 and C6 medial branches).

Mnemonic

WADWhiplash Rule

Women

Higher risk

Axial

Pain pattern

Delayed

Onset can be 24-48hrs

Memory Hook:Epidemiology of facet trauma.

Pathophysiology and Mechanisms

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.

Classification Systems

IASP / Bogduk Diagnostic Criteria

Classification relies on response to diagnostic blocks, not imaging.

Possible Facet Pain: History and Exam suggestive. Imaging shows OA.
Probable Facet Pain: Greater than 80% relief from a SINGLE Medial Branch Block (MBB).
Definite Facet Pain: Greater than 80% relief from TWO comparative blocks (e.g. Lignocaine then Bupivacaine) on different occasions.

Clinical Assessment

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).

Imaging and Investigations

Workup Protocol

X-RayScreening

AP/Lat/Oblique.
Look for: Joint space narrowing, sclerosis, osteophytes.
"Shingle Sign": Visualizes facet alignment on lateral view.

CT ScanBone Detail

More sensitive for OA.
Rule out fracture or lysis.
Note: OA presence does NOT confirm pain source.

Diagnostic BlockGold Standard

Medial Branch Block (MBB).
Injection of local anesthetic (Lignocaine/Bupivacaine) onto the nerve supply.
Diagnostic Criteria: Greater than 80% pain relief for the duration of the anesthetic.

Management Algorithm

Clinical Algorithm— Facet Pain Management

Loading flowchart...

Surgical Technique

Radiofrequency Neurotomy (RFA)

Indication: Positive response to TWO diagnostic blocks.
Goal: Thermal coagulation of the medial branch nerve to interrupt pain signals.
Mechanism: Heat (80-90°C) creates a lesion.

Technique:

Placement: Electrode placed Parallel to the nerve (along the waist of the articular pillar).
Why Parallel?: Electricity flows sideways. Placing the needle perpendicular ("Gun barrel") creates a smaller lesion and might miss the nerve.
Testing:
- Sensory: 50Hz (Patient feels buzzing in neck).
- Motor: 2Hz (Look for multifidus twitch). Absence of arm twitch is critical (Rule out root stimulation).
Lesioning: 90 seconds @ 80°C. Multiple lesions per nerve.

Outcomes:

60-80% of patients get relief.
Duration: 9-12 months (nerve regenerates).
Can be repeated.

Complications

Complication	Risk	Note
Neuritis	Common (5%)	Burning pain (Sunburn feeling). Self-limiting (2-4 weeks).
Motor Nerve Injury	Rare	Drift of needle anteriorly hitting the Nerve Root. Avoid by Motor Testing.
Infection	Very Rare	Epidural abscess.
No Relief	20-30%	Technical failure or Incorrect diagnosis (False pos block).

Non-Operative Management

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.

Postoperative Care

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

Outcomes and Prognosis

Natural History: Recurrent/Relapsing course.
RFA Efficacy: Lord et al showed median relief of 260 days.
Whiplash: Poorer prognosis if litigation ongoing, high baseline pain, or Catastrophizing.

Evidence Base

Prevalence of Facet Pain

Lord et al • Spine (1996)

Key Findings:

Double-blind controlled blocks in chronic whiplash patients.
Identified facet joints as source in 60% of cases.
Most common level: C2/3.
Established the double-block paradigm.

Clinical Implication: Facet pain is the #1 cause of chronic whiplash pain.

Efficacy of RFA

MacVicar et al • Pain Med (2012)

Key Findings:

Review of RFA outcomes enforcing strict selection criteria.
Success rate greater than 60% relief.
Durability 10-12 months.
Critical factor: Proper patient selection (double blocks).

Clinical Implication: Diagnosis is key. If you block correctly, RFA works.

Third Occipital Nerve Headache

Bogduk et al • Cephalalgia (2000)

Key Findings:

C2/3 facet joint pain refers to the head.
Mediated by TON (Third Occipital Nerve).
Distinct entity from Tension HA or Migraine.
Responsive to RFA of TON.

Clinical Implication: Consider C2/3 blocks for 'Cervicogenic Headache'.

Needle Placement Physics

Cosman et al • Pain Physician (2005)

Key Findings:

Parallel placement creates a larger lesion along the nerve.
Perpendicular placement creates a donut lesion that the nerve might slip through.
Use large gauge electrodes (16G-18G).

Clinical Implication: Technique matters. Lie parallel to the pillar.

False Positive Rates

Barnsley et al • Pain (1993)

Key Findings:

Compared single block to double controlled blocks.
False positive rate of single block was 27-40%.
Explanation: Placebo, systemic absorption, spread to muscle.

Clinical Implication: Never trust a single block.

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

Chronic Neck Pain

EXAMINER

"45F, MVA 6 months ago. Chronic neck pain, worse looking up. MRI shows some degeneration C5/6. Physio failed. What is your approach?"

EXCEPTIONAL ANSWER

The history is suggestive of **Cervical Facet Arthropathy** (Axial pain + Extension + Trauma). **Plan**: 1. **Explain**: MRI degeneration is common and may not be the cause. The diagnosis is clinical + interventional. 2. **Diagnosis**: Arrange **diagnostic Medial Branch Blocks**. - Must be done under fluoroscopy. - Need greater than 80% relief to call it positive. - Ideally repeat (double block) to confirm. 3. **Treatment**: If blocks positive → **Radiofrequency Ablation**. If negative → reconsider Disc, Muscle, or central sensitization.

KEY POINTS TO SCORE

Clinical triad (Axial, Extension, Trauma)

Role of MBB

Don't operate (Fusion) for axial pain alone

COMMON TRAPS

✗Offering fusion based on MRI

✗Skipping the diagnostic blocks

VIVA SCENARIOStandard

Cervicogenic Headache

EXAMINER

"A patient complains of unilateral occipital headaches radiating from the neck. Worse with neck rotation. Which joint is culpable?"

EXCEPTIONAL ANSWER

This is classic for **C2/3 Facet Joint** pathology. **Innervation**: - Supplied by the **Third Occipital Nerve (TON)** (dorsal ramus C3). - And the C2 medial branch. **Testing**: - TON block. **Treatment**: - Pulsed or Thermal RFA of the TON. **Differential**: Tension headache, Migraine, Occipital Neuralgia.

KEY POINTS TO SCORE

C2/3 referral pattern

Third Occipital Nerve

Headache differential

COMMON TRAPS

✗Confusing with C1/2 (Atlantoaxial) - which causes rotation loss but different pain

✗Missing Temporal Arteritis in elderly

MCQ Practice Points

Diagnosis

Q: What is the false positive rate of a single uncontrolled medial branch block? A: 30-40%. This is why dual blocks are required for definitive diagnosis.

Anatomy

Q: The C5/6 facet joint is innervated by which nerves? A: C5 and C6 medial branches. (Same level and level above).

Technique

Q: For maximum efficacy, how should the RFA electrode be placed relative to the nerve? A: Parallel. This maximizes the length of nerve captured in the thermal lesion.

History

Q: Which movement typically aggravates facet joint pain? A: Extension and Rotation. This mechanially loads the joint.

Complication

Q: What is the most common side effect of RFA? A: Post-neurotomy Neuritis (Sunburn sensation). Occurs in 5% of patients.

Australian Context

Whiplash

Major burden on TAC (Victoria) and CTP schemes.
"Common Law" claims often hinge on the diagnosis of a permanent injury. RFA is considered a treatment for a "permanent" condition (nerve damage/pain).

Public System Coverage

Medial branch blocks and radiofrequency ablation procedures covered under public hospital system.

Epidemic

Australia has high rates of whiplash chronicity compared to countries with 'no-fault' insurance, suggesting a pyschosocial element to recovery.

Exam Day Cheat Sheet

Facet Summary

High-Yield Exam Summary

Key Concepts

•Axial Pain (No Radiculopathy)
•Extension Loading pattern
•MBB is gold standard diagnosis
•Double block required

Anatomy

•Dual Innervation (Same + Above)
•C2/3 = Headache (TON)
•C5/6 = Shoulder
•Facet angles 45 deg

Treatment

•Conservative first
•RFA (Parallel placement)
•Success = 9-12 months relief
•No Fusion
•Sensory + Motor Testing

Stats

•60% of WAD patients
•30% False Positive Rate (Single Block)
•55% Chronic Neck Pain
•F>M Prevalence

Image Manifest

[1-preoperative-image-a-plain-radiograph-lateral-imag.png]: Lateral X-ray showing facet sclerosis
- [5-plain-radiographs-of-a-57-year-old-man-a-lateral-i.png]: Lateral spondylosis

Feature

Facet Joint (Z-Joint)

Discogenic Pain

Radiculopathy

Primary Pain

Neck (Axial)

Arm (Radicular)

Aggravation

Extension / Rotation

Flexion / Loading

Extension / Spurling's

Referral

Somatic (Head/Scapula)

Somatic (Interscapular)

Dermatomal (Hand)

Deficits

None

Motor/Sensory Loss

Complication

Risk

Note

Neuritis

Common (5%)

Burning pain (Sunburn feeling). Self-limiting (2-4 weeks).

Motor Nerve Injury

Rare

Drift of needle anteriorly hitting the Nerve Root. Avoid by Motor Testing.

Infection

Very Rare

Epidural abscess.

No Relief

20-30%

Technical failure or Incorrect diagnosis (False pos block).

Prevalence of Facet Pain

Lord et al • Spine (1996)

Key Findings:

Double-blind controlled blocks in chronic whiplash patients.
Identified facet joints as source in 60% of cases.
Most common level: C2/3.
Established the double-block paradigm.

Clinical Implication: Facet pain is the #1 cause of chronic whiplash pain.

Efficacy of RFA

MacVicar et al • Pain Med (2012)

Key Findings:

Review of RFA outcomes enforcing strict selection criteria.
Success rate greater than 60% relief.
Durability 10-12 months.
Critical factor: Proper patient selection (double blocks).

Clinical Implication: Diagnosis is key. If you block correctly, RFA works.

Third Occipital Nerve Headache

Bogduk et al • Cephalalgia (2000)

Key Findings:

C2/3 facet joint pain refers to the head.
Mediated by TON (Third Occipital Nerve).
Distinct entity from Tension HA or Migraine.
Responsive to RFA of TON.

Clinical Implication: Consider C2/3 blocks for 'Cervicogenic Headache'.

Needle Placement Physics

Cosman et al • Pain Physician (2005)

Key Findings:

Parallel placement creates a larger lesion along the nerve.
Perpendicular placement creates a donut lesion that the nerve might slip through.
Use large gauge electrodes (16G-18G).

Clinical Implication: Technique matters. Lie parallel to the pillar.

False Positive Rates

Barnsley et al • Pain (1993)

Key Findings:

Compared single block to double controlled blocks.
False positive rate of single block was 27-40%.
Explanation: Placebo, systemic absorption, spread to muscle.

Clinical Implication: Never trust a single block.