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Indications / Contraindications
Indications
- Axial spinal pain (cervical, thoracic, lumbar) attributed to facet arthropathy — characteristically worse with extension and rotation; without significant radicular component
- Diagnostic medial branch block (MBB) to confirm facet origin before radiofrequency ablation (RFA)
- Therapeutic intra-articular injection — short-to-medium term pain relief
- Failed conservative management ≥ 6 weeks
- Clinical criteria favoring facet origin: age >50, no radiation below the knee, pain not worsened with walking, relieved with sitting
Contraindications
- Absolute: Active spinal infection · Uncorrectable coagulopathy · Allergy to contrast or corticosteroids
- Relative: Anticoagulation (hold per SIR Cat 1 guidelines before proceeding) · Uncontrolled diabetes (steroid-related glucose spike) · Prior RFA at same level without adequate washout
- Note: SIR Category 1 — routine coagulation correction not required; targeted hold for therapeutic anticoagulation
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Pre-Procedure Checklist
Review MRI. Look for facet hypertrophy, joint space narrowing, subarticular bone marrow edema on STIR sequences. Identify target level(s). Most common lumbar levels: L3-4, L4-5, L5-S1. Most common cervical: C3-4 through C6-7.
Fluoroscopy planning. Confirm C-arm availability. Identify approach: oblique view for intra-articular vs. AP for medial branch block.
Goal clarification. Diagnostic MBB (short-acting agent only, 0.5 mL per nerve) vs. therapeutic intra-articular injection (steroid + longer-acting anesthetic). This determines needle, agent, and outcome interpretation.
Anticoagulation (SIR Cat 1 — low risk). No routine holds required. Warfarin: continue if INR ≤3.0. DOACs: optional 12–24h hold for therapeutic dosing at operator discretion. Aspirin/NSAIDs: continue. Therapeutic anticoagulation: brief hold (IV heparin 2–4h; LMWH 1 dose) if clinically feasible.
Consent. Discuss: post-injection pain flare (10–20%, resolves 1–3 days), infection (<1%), intravascular injection (rare but catastrophic with particulate steroid), nerve root injury, epidural spread, limited steroid injections (3 per year per anatomic region).
Diabetic patients. Warn about transient glucose elevation post-steroid. Check recent HbA1c if possible. Arrange blood glucose monitoring for 24–48h after injection.
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Relevant Anatomy
Facet Joint
- Zygapophyseal joint — articulation between the superior articular process of the vertebra below and the inferior articular process of the vertebra above
- True synovial joint with joint capsule; capacity 1–2 mL — overfilling causes capsular rupture and epidural spread
- Lumbar facets oriented sagittally (resist rotation); cervical facets oriented obliquely
- On oblique fluoroscopy: "Scottie dog" — ear = superior articular process (SAP), eye = pedicle, nose = transverse process, front leg = inferior articular process
Medial Branch Nerve Targets
- Each facet joint is innervated by the medial branch of the dorsal ramus from TWO levels — the level above and the level of the joint itself
- Lumbar L1–L4 medial branch: crosses at junction of transverse process and superior articular process — target is the "waist" or "neck" of the Scottie dog
- L5 dorsal ramus: courses in groove between sacral ala and S1 SAP — slightly different target than L1–L4
- Cervical medial branch: targeted at midpoint of articular pillar (C3–C7)
- Rule: To block a facet at level X, block the medial branches at level X and X-1
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Technique
Default RadCall approach · share your own below
Supplies
22G or 25G spinal needle
C-arm fluoroscopy
Omnipaque 180 (contrast)
1 mL + 3 mL syringes
Extension tubing (primed)
1% lidocaine or 0.25% bupivacaine
Methylprednisolone 40 mg or Triamcinolone 40 mg
ChloraPrep
Sterile drape
Sterile dressing
Approach A — Intra-Articular Injection
Steps
1
Position + fluoroscopy setup
Patient prone. Rotate C-arm to ipsilateral oblique 30–45° to open the joint — the targeted facet joint space should appear as a clear lucent line on the image.
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Skin entry + needle advance
Local anesthesia at skin. Advance 22G spinal needle toward inferior recess of the joint under continuous fluoroscopy. Needle tip should track along the joint line.
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Confirm position AP + lateral
Obtain AP and lateral fluoroscopic views. On AP: needle tip overlies joint space. On lateral: tip projects within the posterior joint at the level of the interlaminar space.
▶ Facet joint — fluoroscopic needle placement
AP fluoroscopic view: needle tip overlying facet joint — oblique view opens the joint space; confirm intra-articular position with small contrast arthrogram before injection.
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Contrast arthrogram
Gentle injection of 0.3–0.5 mL contrast under live fluoroscopy. Confirm intra-articular position — contrast should outline the joint capsule (ovoid or crescent shape). STOP if contrast flows linearly into a vessel or spreads widely epidurally.
▶ Contrast arthrogram — intra-articular confirmation
Facet arthrogram: contrast within the joint capsule — classic “bowtie” appearance confirms intra-articular placement; extravasation suggests capsular rupture.
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Inject medication
Once intra-articular confirmed: inject 1 mL corticosteroid (methylprednisolone 40 mg or triamcinolone 40 mg) + 0.5 mL local anesthetic (0.25% bupivacaine). Total volume ≤1.5 mL to avoid capsule rupture.
Approach B — Medial Branch Block (MBB)
Steps
1
Identify target levels
To block a facet at level X, you must block medial branches at X-1 AND X. For L4-5 facet: block L3 and L4 medial branches. For L5-S1: block L4 medial branch and L5 dorsal ramus (at sacral ala).
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AP fluoroscopy — needle to target
AP view. For L1–L4 medial branches: advance 25G needle to the junction of the superior articular process and transverse process ("waist of the Scottie dog"). For L5 dorsal ramus: target the groove between sacral ala and S1 SAP.
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Lateral view depth confirmation
Obtain lateral view. Needle tip should project at the posterior cortex of the junction, approximately halfway between the spinous process and the posterior vertebral body line. Do not advance anterior to this.
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Contrast check
Inject 0.2–0.3 mL contrast under live fluoroscopy. Confirm no intravascular uptake (no linear flow in vessels). Small local spread is acceptable.
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Inject local anesthetic ± steroid
Diagnostic MBB: 0.5 mL 1% lidocaine per nerve (short-acting — 2–4h; ideal for diagnostic confirmation before RFA). Therapeutic MBB: 0.5–1 mL local anesthetic + 0.5 mL corticosteroid. Repeat at each level required. Document volumes precisely.
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Troubleshooting
Problem
Intravascular contrast uptake on test injection
Likely cause: Needle tip in epidural venous plexus or periforaminal vessel — more common at cervical and thoracic levels.
Next step: Withdraw needle 1–2 mm and re-aspirate. Redirect slightly. Repeat contrast injection under live fluoroscopy before any medication. If vascular uptake persists, abort and reposition needle. Never inject particulate steroid with active vascular uptake.
Problem
Cannot access joint — too narrow or degenerated
Likely cause: Advanced facet arthropathy with complete joint space obliteration; osteophytes blocking entry.
Next step: Increase oblique angle. Try inferior recess first (often most patent). If still inaccessible, target medial branch block instead — equally effective for diagnostic purposes. Consider CT guidance for C7-T1 or severely degenerated joints.
Problem
Contrast spreads widely / epidural pattern instead of intra-articular
Likely cause: Needle tip through posterior joint capsule into epidural or paraspinal space; or existing capsular defect from prior injections.
Next step: Withdraw needle to re-enter joint proper. If a capsular defect allows medication to track epidurally, reduce volume to 1 mL total. Document the finding — epidural spread may still be therapeutic but the procedure is technically a pericapsular injection.
Problem
Difficult C7-T1 access
Likely cause: Shoulder overlap blocks oblique fluoroscopic view at the cervicothoracic junction.
Next step: Use CT guidance for C7-T1 and T1-2. Alternatively, use a "swimmer's" lateral fluoroscopic view. Pull shoulders caudally with traction during AP/oblique views. Consider prone lateral approach under CT.
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Complications
Immediate / Periprocedural
- Post-injection flare (10–20%) — transient pain increase 1–3 days post; resolves spontaneously; ice/NSAIDs helpful; warn patient before discharge
- Intravascular steroid injection — particulate steroid into radicular artery → spinal cord infarct (catastrophic but rare); use live fluoroscopy + contrast mandatory before every injection
- Epidural spread (inadvertent) — from capsular defect or excessive volume; monitor for lower extremity weakness or sensory changes before discharge
- Vasovagal reaction — common; supine positioning, fluids, atropine if needed
- Nerve root injury — rare; usually transient paresthesias from needle contact; reposition immediately
Delayed
- Infection / Septic arthritis (<0.1%) — fever, worsening pain, elevated WBC; spine MRI with contrast; broad-spectrum antibiotics; IR or surgical drainage if abscess forms
- Corticosteroid side effects — hyperglycemia (warn diabetics, 24-48h monitoring), adrenal suppression (limit to 3 injections per region per year), Cushing features with repeated use
- Skin/subcutaneous atrophy — from superficial steroid deposition; use deep, confirmed intra-articular injection
- Hematoma — rare (Cat 1 procedure); usually self-limited
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Post-Procedure Care
Same Day
- Observe 20–30 min — check for inadvertent epidural spread (leg weakness) and vasovagal recovery
- Pain diary: instruct patient to document degree and duration of relief starting immediately post-procedure using the online pain diary tool
- Patient must have a driver if local anesthetic was used near neural structures
- Ice application to injection site for discomfort
- Resume normal activity as tolerated — light activity day of, no strenuous exercise for 24h
- Diabetic patients: check blood glucose at home for 24–48h
Follow-up + Decision Points
- Pain diary review at 2 weeks. Document: degree of relief (%), duration of relief (hours/days)
- Positive diagnostic MBB: ≥50–80% pain relief for ≥6 hours with short-acting agent → proceed to RFA workup
- Dual diagnostic blocks: Two positive MBBs (lidocaine then bupivacaine, separate visits) before RFA improves specificity and reduces RFA failure rates
- Therapeutic injection assessment at 4–6 weeks. If >50% relief — document and consider repeat if relapse. If inadequate — reassess diagnosis; consider alternative source (SI joint, disc, myofascial)
- Steroid limit: Maximum 3 injections per anatomic region per year
💡
Provide patient with a pain diary to track daily pain scores before their follow-up visit — helps calibrate treatment response and guides repeat intervention decisions.
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Critical Pearls
✶
Live fluoroscopy + contrast before EVERY steroid injection. Intravascular injection of particulate steroid (methylprednisolone, triamcinolone) into a radicular artery causes spinal cord infarction. Never skip this step. Use real-time fluoroscopy — not just a static spot film — to confirm no vascular uptake before injecting.
✶
Diagnostic MBB is the gatekeeper to RFA. Use short-acting lidocaine for initial diagnostic block. Confirm ≥50–80% relief for ≥6 hours. Use dual sequential blocks (lidocaine then bupivacaine) to increase specificity. RFA without adequate diagnostic confirmation has high failure rates.
✶
Small volumes for diagnostic MBB. Use 0.5 mL per nerve only. Larger volumes spread to adjacent structures (epidural space, adjacent medial branches), producing false-positive diagnostic blocks and contaminating data for RFA planning.
✶
Block BOTH medial branches supplying the joint. Each facet joint is innervated from two levels. To block the L4-5 facet: block the L3 medial branch AND the L4 medial branch. Missing one branch produces incomplete analgesia and an equivocal diagnostic result.
✶
L5 dorsal ramus target is unique. Unlike L1–L4 medial branches, the L5 dorsal ramus is targeted in the groove at the sacral ala / S1 SAP junction — not at the transverse process. Confusing this target is a common error that leads to failed diagnostic blocks at L5-S1.
✶
Post-injection flare is common and expected. Warn the patient before they leave: 10–20% experience a temporary pain increase for 1–3 days due to the needle itself and crystalline steroid. This does not mean the injection failed. The therapeutic benefit from the steroid begins 2–5 days later and peaks at 1–2 weeks.
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References & Medial Branch Level Guide
Medial Branch Nerve Supply by Facet Level
| Facet Joint | Medial Branch Block Targets | Special Notes |
|---|---|---|
| C3-4 | C3 medial branch (deep) + C4 medial branch — articular pillar midpoint | Third occipital nerve for C2-3; 3rd occipital headache pattern |
| C4-5 | C4 + C5 medial branches | Articular pillar midpoint; lateral approach preferred |
| C5-6 | C5 + C6 medial branches | Most common cervical level treated |
| C6-7 | C6 + C7 medial branches | C7-T1 access often requires CT guidance |
| L1-2 to L3-4 | Level above + same level medial branches (e.g., L3-4: block L2 + L3 MB) | Junction of TP and SAP ("waist of Scottie dog") |
| L4-5 | L3 medial branch + L4 medial branch | Most commonly treated lumbar level |
| L5-S1 | L4 medial branch + L5 dorsal ramus | L5 DR target: sacral ala / S1 SAP groove — different from other levels |
Citations
- Prologo JD, Ray CE Jr., eds. Advanced Pain Management in Interventional Radiology: A Case-Based Approach. Thieme; 2024. DOI: 10.1055/b000000387
- Filippiadis DK, Kelekis A. A review of current trends in spinal interventional procedures for the management of chronic spinal pain. Quant Imaging Med Surg. 2017;7(6):651–659.
- Manchikanti L, et al. Comprehensive evidence-based guidelines for facet joint interventions in the management of chronic spinal pain. Pain Physician. 2020;23(3):S1–S127.
- Bogduk N. International Spine Intervention Society. Practice Guidelines for Spinal Diagnostic and Treatment Procedures. 2nd ed. ISIS; 2013.
- SIR Standards of Practice Committee. Consensus Guidelines for Periprocedural Management of Coagulation Status. J Vasc Interv Radiol. 2012;23(6):727–736.
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References & Resources
Primary sources · Key data · Related procedures
Key Guidelines
- ISIS Practice Guidelines for Facet Injection
- ASIPP Evidence-Based Guidelines for Diagnostic and Therapeutic Facet Joint Interventions
- ACR Appropriateness Criteria for Low Back Pain
Primary References
- Bogduk N. International Spinal Injection Society guidelines for the performance of spinal injection procedures. Part 1: Zygapophysial joint blocks. Clin J Pain. 1997;13(4):285-302.
- Manchikanti L et al. A systematic review of the effectiveness of lumbar facet joint nerve blocks. Pain Physician. 2007;10(3):425-460.
- Schwarzer AC et al. The prevalence and clinical features of internal disc disruption in patients with chronic low back pain. Spine. 1995;20(17):1878-1883.