Facet joint-mediated pain is a common consideration in patients with persistent axial spinal pain, particularly in the lumbar and cervical spine.

Yet the terminology surrounding facet interventions can be confusing. Patients may describe having had a “facet injection”, “nerve block” or “denervation” without being entirely sure what was performed, and these procedures are sometimes discussed as though they are alternative versions of the same treatment.

They are not.

Understanding the distinction between intra-articular facet joint injections, medial branch blocks and radiofrequency denervation is important when deciding what role, if any, an intervention might have in a patient's management.

What are the facet joints?

The facet—or zygapophyseal—joints are paired synovial joints at the back of the spine.

Like other synovial joints, they can undergo degenerative change and may contribute to pain. However, degenerative changes on imaging are common and do not establish that a facet joint is the source of a patient's symptoms.

This is particularly important because there is no single history, examination finding or MRI appearance that reliably confirms facet-mediated pain.

Diagnosis is therefore primarily clinical, sometimes supported by diagnostic blocks of the nerves supplying the joints.

Intra-articular facet joint steroid injections

A facet joint injection involves placing a needle directly into the joint, usually using fluoroscopic or other image guidance, and injecting local anaesthetic, often together with corticosteroid.

The rationale is similar to injecting other painful synovial joints: if inflammation within the joint is contributing to symptoms, corticosteroid may reduce that inflammatory component.

Some patients obtain useful relief.

However, the evidence for repeated therapeutic facet joint steroid injections in chronic axial spinal pain is limited, and any benefit may be relatively short-lived.

Importantly, injecting steroid into a facet joint is quite different from performing a medial branch block.

What is a medial branch block?

The facet joints receive their sensory innervation predominantly through small nerves called the medial branches of the dorsal rami.

Rather than injecting the joint itself, a medial branch block places a small volume of local anaesthetic around the nerves supplying the suspected painful joint or joints.

The principal purpose is usually diagnostic or prognostic.

If temporarily anaesthetising these nerves produces substantial relief of the patient's usual pain, this provides evidence that the facet joints they supply may be contributing meaningfully to the pain presentation.

That information can then help determine whether radiofrequency treatment is appropriate.

This distinction is important:

A medial branch block is not simply another type of steroid injection.

Indeed, steroid is not required for the diagnostic component of a medial branch block.

What is radiofrequency denervation?

Radiofrequency denervation—also called radiofrequency ablation or radiofrequency neurotomy—is intended to provide a longer period of relief.

Under image guidance, radiofrequency needles are positioned adjacent to the relevant medial branch nerves. Radiofrequency energy is then used to produce a controlled thermal lesion, interrupting transmission through those nerves.

The facet joint itself is not removed or destroyed.

And despite the term denervation, the effect is not necessarily permanent. Peripheral nerves can recover or regenerate, so pain may return over time.

For appropriately selected patients who respond convincingly to diagnostic medial branch blocks, radiofrequency treatment can provide a longer period of pain reduction than local anaesthetic or steroid injections alone.

So why not go directly to radiofrequency treatment?

Because the difficult part is not performing the radiofrequency procedure.

The difficult part is identifying the right patient.

Facet joint degeneration on an MRI does not tell us reliably whether those joints are responsible for the patient's pain.

Axial back pain may arise from several structures and mechanisms, and these frequently coexist. Treating an anatomical abnormality simply because it is visible on imaging risks performing an intervention that has little chance of changing the patient's symptoms.

Diagnostic medial branch blocks therefore provide useful additional information before considering a more prolonged intervention.

The precise diagnostic pathway—including the number of blocks and threshold regarded as a meaningful response—varies between guidelines, healthcare systems and clinical circumstances.

Where does steroid fit?

This is where patients can understandably become confused.

Steroid may be used therapeutically within a facet joint in selected circumstances.

A diagnostic medial branch block, by contrast, is primarily designed to establish whether temporarily blocking the nerve supply to a facet joint substantially alters the patient's usual pain.

Radiofrequency treatment then targets those nerves with the intention of producing a more sustained effect.

So although all three procedures may be described loosely as “facet treatments”, their purposes are different.

Individual responses vary considerably, and none of these procedures should be presented as a permanent cure.

Radiofrequency treatment is not a substitute for rehabilitation

Successful radiofrequency treatment should ideally create an opportunity, rather than an endpoint.

Someone who has spent months or years moving differently because of pain may have developed deconditioning, protective movement patterns, reduced confidence and understandable fear of provoking symptoms.

Reducing facet-mediated pain does not automatically reverse these consequences.

A period of improved pain control can therefore be particularly valuable when used to support progressive activity, physiotherapy and rehabilitation.

This is one reason communication between the pain clinician and the patient's physiotherapist can be so useful.

What if the diagnostic block doesn't work?

A negative block is useful information too.

It may suggest that the suspected facet joints are not a major contributor to the patient's pain, or that another mechanism deserves greater consideration.

That does not mean the pain is unexplained or that there are no further options.

It means that proceeding automatically to radiofrequency treatment is unlikely to be the most useful next step.

Good interventional pain medicine includes knowing when not to intervene.

Selecting patients carefully

Facet interventions work best when they form part of a wider clinical assessment.

The question is not simply:

“Does this patient have facet joint degeneration?”

It is:

“Is facet-mediated pain sufficiently likely and sufficiently important within this person's overall pain presentation that targeting it has a reasonable chance of helping?”

For some patients, the answer will be yes.

For others, addressing a different pain mechanism—or concentrating on rehabilitation, medication optimisation, psychological approaches, sleep, activity or wider health factors—may offer more value.

The procedure should follow the diagnosis, rather than the diagnosis following the scan.

For clinicians

Wye Sanctuary accepts referrals and self-referrals for assessment of persistent spinal pain, including patients where the contribution of facet-mediated pain is uncertain or where advice is required regarding interventional treatment.

Where an intervention is appropriate, we aim to integrate this with the patient's wider rehabilitation plan and are happy to liaise with their existing physiotherapist or other treating clinicians.

This article is intended for general professional education and does not replace individual clinical assessment or applicable local and national guidance.