When do you perform a facet joint injection versus a medial branch block for facetogenic lumbar pain?

Medial Branch Blocks vs. Facet Joint Injections for Facetogenic Lumbar Pain

Medial branch blocks should be performed rather than intra-articular facet joint injections for diagnosing and treating facetogenic lumbar pain, as they demonstrate better prognostic value for subsequent interventions and superior therapeutic outcomes. 1, 2

Diagnostic Approach

• The double-injection technique with an improvement threshold of 80% or greater is recommended to establish the diagnosis of lumbar facet-mediated pain (Grade B recommendation) 3
• Medial branch blocks are superior to intra-articular facet joint injections as a prognostic tool before radiofrequency denervation, with 70.3% of MBB patients experiencing ≥50% pain relief at 3 months versus 60.8% in those who underwent intra-articular injections 1
• Diagnostic facet blocks are considered the most reliable means of identifying facet-mediated pain, as no physical or radiographic findings consistently correlate with facet pain 2

When to Choose Medial Branch Blocks

• Use medial branch blocks when:
  • Planning for potential radiofrequency ablation, as MBBs better predict treatment success (OR 1.57; 95% CI 1.0-2.39) 1
  • Seeking short-term pain relief for facet-mediated chronic low back pain, as they show better evidence for therapeutic efficacy compared to intra-articular injections 2
  • Each medial branch block injection provides on average 15 weeks of pain relief for low back pain and improved function 2
• The American Society of Interventional Pain Physicians recommends facet medial nerve blocks for short-term pain relief rather than intra-articular injections, with moderate evidence supporting this use 3

When to Consider Facet Joint Injections

• Intra-articular facet joint injections may be considered when:
  • The patient is not a candidate for radiofrequency denervation 2
  • The goal is purely diagnostic without therapeutic intent 4
• However, multiple studies have failed to demonstrate the effectiveness of facet joint injections as a therapeutic intervention for chronic low back pain, with only 7.7% of patients achieving complete relief of symptoms 2
• The American College of Neurosurgery explicitly recommends against intra-articular facet injections for chronic low back pain from degenerative lumbar disease 4

Treatment Algorithm

1. First establish diagnosis of facetogenic pain through clinical assessment:

   • Pain patterns: lower facet joints refer to groin and posterior thigh; upper joints to flank, hip, and lateral thigh 2
   • Absence of radiculopathy 2
   • Pain persistence for more than 3 months 2
   • Failed conservative treatment for at least 6 weeks 3, 4

2. Perform diagnostic medial branch block:

   • One block of the ramus medialis of the ramus dorsalis is sufficient before considering radiofrequency treatment 5
   • Double-block technique is more reliable but rarely performed in routine clinical practice 2

3. If positive response to diagnostic block (≥50% pain relief):

   • Proceed with radiofrequency ablation of the medial branch nerves, which is considered the "gold standard" for treating facetogenic pain (1 B+) 6, 7
   • Conventional (80°C) or thermal (67°C) radiofrequency ablation of the medial branch nerves should be performed when previous diagnostic blocks have provided temporary relief 7

4. If radiofrequency treatment fails:

   • Consider intra-articular corticosteroids as a second-line option (2 B±) 6

Common Pitfalls to Avoid

• Proceeding with interventional procedures before completing an adequate trial of conservative management (at least 6 weeks) 3, 4
• Relying solely on imaging findings of facet arthropathy to justify interventional treatment 3, 4
• Using facet joint interventions for patients with untreated radiculopathy 2
• Confusing the diagnostic utility of facet blocks with their therapeutic value 4
• Failing to recognize that opioid use (OR 0.52) and previous back surgery (OR 0.60) are associated with treatment failure following radiofrequency denervation 1