Facet joint injections (facet blocks) and medial branch blocks are often recommended for individuals who have back pain associated with arthritic changes in their spinal facet joints. There is one key difference between these two outpatient procedures. A facet block is an injection of a local anesthetic and a steroid medication directly into a spinal facet joint. A medial branch block is a similar injection that is placed outside the joint space near the nerve (medial branch) that serves the joint.

What can be achieved with an injection?

Facet joint injections and medial branch blocks can be performed for both diagnostic and therapeutic reasons. In either case, there are three possible outcomes:

1. The pain persists. This means that the targeted facet joint is unlikely to be the cause of the symptoms.
2. The pain temporarily resolves but then returns. This means that the targeted facet joint is likely the pain generator, but the inflammation did not respond to the steroid medication.
3. The pain goes away for a few hours and then returns, but improves significantly over the next few days. This means that the inflammation responded to the steroid medication.

Some physicians encourage their patients to keep a journal to track the levels and duration of the pain relief they experience following an injection. This information can be helpful when evaluating the success of the treatment. Sometimes, if a significant and lasting improvement is achieved, a block may be repeated if and when the symptoms return. On the other hand, if the result is good but short-lived, a physician may recommend another procedure, such as facet thermal ablation, that more effectively targets the treated joint.

When to consider injections

If you’ve tried to manage your back pain with conservative treatments, such as medications, exercise and hot/cold therapy, but have not found sufficient relief, your physician may recommend one or more facet joint injections or medial branch blocks. This type of procedure can confirm that a specific facet joint is the source of your pain, and also potentially reduce your symptoms to the point that you can resume your daily activities.