Facet Joint Arthropathy

**Lumbar facet arthropathy** typically presents as:

• Axial low back pain — aching, deep, difficult to localize precisely
• Extension-loaded pain: Worse with standing, walking, arching backward (lumbar extension), and twisting
• Pain that radiates into the buttocks and proximal posterior thighs — but characteristically not below the knee in a dermatomal pattern
• Morning stiffness that improves with movement
• Paraspinal tenderness on palpation lateral to the spinous processes
• Axial neck pain and shoulder girdle pain
• Pain worsened by cervical extension and rotation
• Referral into the occiput (C2–C3, C3–C4) or shoulder/upper arm (C5–C6, C6–C7)
• Post-whiplash chronic neck pain is commonly maintained by cervical facet joint inflammation

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Clinical examination: Assessment of lumbar and cervical range of motion, palpation for paraspinal tenderness, pain reproduction with extension and rotation, and a complete neurological evaluation to exclude radiculopathy or myelopathy. Imaging features of facet arthropathy on MRI (joint effusion, capsular hypertrophy, articular surface irregularity) support the diagnosis but do not confirm it as the pain source.

Medial branch block (MBB), the diagnostic standard: The only reliable way to confirm a facet joint as a significant pain generator is to anesthetize its nerve supply. A medial branch block involves fluoroscopically guided injection of a small volume of local anesthetic onto the medial branch(es) of the dorsal ramus that innervates the suspected joint(s). Because each joint is innervated by two medial branches, MBBs are typically placed at two levels per target joint.

• Positive response: ≥50–80% reduction in concordant pain (the threshold varies by institutional protocol and insurance requirement) during the anesthetic window
• Controlled blocks: To reduce the false-positive rate (estimated at 25–40% for single diagnostic blocks), many pain management protocols require two comparative MBBs using different duration anesthetics (short-acting vs. long-acting). A positive result requires concordant relief with each

Imaging:

• MRI assesses overall spinal degeneration, disc pathology, and facet joint changes
• CT scan provides the most detailed view of facet joint anatomy, osteophyte formation, and joint space narrowing
• Plain radiographs are used for alignment assessment and initial evaluation

Patients who respond to medial branch blocks and undergo RFA typically experience progressive pain relief over 2–6 weeks post-procedure as the ablated nerves complete degeneration. Return to full activity is usually possible within 2–4 weeks. Maintenance PT is recommended to prevent deconditioning and reduce the rate of symptom recurrence. When symptoms return (usually correlated with nerve regeneration), repeat diagnostic block followed by repeat RFA is a safe and effective strategy.