BACK PAIN – INJECTIONS
The lumbar facet joints are easily accessible for both techniques and are served by a specific nerve supply that has little in the way of cutaneous representation. Although the injections may be considered by the casual observer, and the patient, to be similar procedures, they are in fact different in respect of the target for injection and the rationale for the procedure. The former is an attempt to treat the joint itself, the latter is an attempt to interrupt the pain pathways from the joint. Such diversity of rationale has hampered the quest for evidence for efficacy for these injections, as experts have their own techniques. The actual technique of injection may vary between clinicians and may be accomplished with varying degrees of difficulty depending upon the radiological appearance. Whereas the ‘gold standard’ for injection is the accurate placement of a low volume of anaesthetic within the joint or on the medial branch of the segmental posterior primary ramus, it may be difficult or impossible to achieve, and anaesthetic may, instead, be deposited on adjacent paravertebral tissues and somatic nerve roots, leading to a clinical effect that may be falsely attributed to facet joint involvement.