Facet Joint Diagnosis and Treatment
The Facet joints are a common cause of dominant back pain (backache, lumbago etc). Pain is usually localize to the level of the facet but may radiate into the leg and facet problems can contribute to nerve entrapment and sciatica. The joints are quie small and are meant to stabilize the spine in rotation and extension but not to be weight bearing. Therefore, facet problems often follow longstanding disc problems where the disc no longer functions and the facet gets stressed, or in more generalised cases of osteoarthritis where the facet becomes “arthriticy”, these joints can be a significant contributor to pain. It is estimated to be a significant pain source in 40% of older spines
Facet injections are given by many clinicians and can give temporary relief from this pain. However, as with injections in most sites, such relief doesn’t usually prove permanent. I therefore tend to try to use medial branch block and denervations which are aimed at achieving permanent relief.
Facet Medial Branch Block:
The nerves which supply sensation to the lumbar facet joint (the medial branches) have been clearly defined by Prof Bogduk and colleagues in both the cervical (neck) and lumbar (lower back) spine. These lie in a reproducible position on the neck of the SAP (it’s technical) and can be targetted there under fluoroscopy. These nerves supply no other structure which would credibly be a cause of chronic spinal pain, so the logic is that if a targeted injection of a small volume of local anaesthetic (0.3-0.5ml) deposited exactly onto this tiny nerve branch completely (or almost completely) relieves back pain, the pain can be presumed to be coming from the facet joint. Therefore patients can be selected for treatment by a positive response to facet block. Technically, for best treatment results 2 blocks should be performed to reduce false positive responses which can occur. In practice, if I have a good clear response to a single block I feel that is sufficient and will go ahead with treatment as below.
Facet Radiofrequency Lesioning:
The patient who has responded to a diagnostic medial branch block in a way that suggests that most or all of their pain is coming from the facet can be treated by placing an electrode, usually with a 1cm long heating tip onto the medial branch (the same nerve that was blocked with local anaesthetic) and heating the nerve branch to 80’C for 1 minute. This heat is sufficient to disrupt nerve tissue but is not hot enough to burn or char the adjacent tissues and so selectively removes the nerve leaving the facet joint without sensation (effectively anaesthetized) over the long term. IN most cases, using the ISIS technique for denervation a result once obtained last for the foreseeable future. Some require to be redone at an ntevsl and of course not all treatments work, even after apparently successful diagnostic block. Note: the effect of this heating is usually painful and this is a treatment where I routinely warn patients to expect that back will be as spiteful as it ever is for anything up to 2-4 weeks afterwards, so this should not be done the day before your daughter’s wedding!
Cervical Facet Treatment:
The work of Prof Bogduk and Dr Lord from Perth western Australia showed that in as many as 50% of cases of post whiplash cervical pain the source was the cervical facet joints. These are also a fairly common cause of neck pain in the older/middle-aged group. Treatment is the same as in the lumbar spine with diagnostic block and RF lesioning.