The cause or causes of lower back pain can be identified only, with certainty and based on clinical examination alone, in about 15 percent of patients. Back pain caused by facet (zygapophyseal) joints can occur in between 15 percent to 45 percent of patients who experience back pain. In this prospective, nonrandomized, consecutive study, researchers evaluated how common facet joint pain was among patients with chronic lower back pain that occurred after surgery of the lumbar spine.
One hundred seventeen patients took part in this study. They had to have had their surgery at least one year before surgery and had to have experienced pain for at least six months after the procedure. Almost half of the patients (45 percent) had undergone more than one surgery. All of the patients had tried other treatments to relieve the pain, including medications, physical therapy, and bedrest, but hadn’t been successful.
The researchers tested for facet joint pain by injecting an anesthetic block (lidocaine) into to each facet joint nerve of each patient. If the patient showed an 80 percent or more improvement in pain after the injection, this was a positive result. All of the patients were given the lidocaine block and if their results were positive after the lidocaine, the patients were given a second block of bupivacaine three or four weeks later. Sixty-seven patients had positive results from the lidocaine block and of those 67, 19 had positive results from the bupivacaine block.
From the study findings, the researchers reported that 16 percent of the patients with lower back pain and suspected facet joint pain did, indeed, have facet joint pain, and that the prevalence was 8 percent in the overall population. The researchers noted that although more studies are needed in order to better understand patient response and to improve clinical practice guidelines, using diagnostic facet joint nerve blocks to diagnose facet joint pain was relevant and useful.