There are no serum biomarkers for the condition at present, he noted.
In addition to older age and these findings on imaging, other risk factors and correlates for facet joint OA include sex (women are 1.5-1.9 times more likely than men to have facet joint OA), race (African Americans are about 60% less likely than white Americans to have facet joint OA), and high body mass index (those with BMI of 25-30 and 30-35 have a three- and fivefold increased risk of lumbar pain associated with facet joint OA, respectively, compared with those with BMI below 25).
Abdominal aortic calcifications and more sagittal orientation of the joints (vs. coronal orientation), also are associated with facet joint OA, Dr. Gellhorn said.
With additional research, these factors could be useful for "disambiguating nonspecific low back pain," he said.
"I think we’re getting closer. We’re not there yet, but we’re getting closer," he said.
Clinically, facet joint OA often presents as localized back or neck pain at C5-C6 with some radiation into the scapular region.
"It’s less clear in the lumbar spine, but almost always people will have pain in the lumbar region, and almost always they will have pain that radiates into the buttocks," he said, noting that pain radiating into the anterior or lateral thighs can be associated with facet joint OA, but pain that extends below the knees is more likely to be radicular.
There are no specific examination maneuvers that are pathognomonic – or even particularly helpful – for the condition, he added.
It is important to keep in mind that many patients will have associated conditions, including spondylolisthesis, disc degeneration, scoliosis, muscle atrophy, and spinal stenosis.
"It’s easy to get overwhelmed in the face of this, but I would urge you not to, and to still try to disentangle some of these concepts of low back pain without throwing up your hands," he said.
Although anesthetic blockade of the medial branches of the dorsal primary ramus (or "medial branch blocks,") are considered the gold standard for diagnosis, they are controversial, have an unacceptably high rate of false-positive results with a single block, and thus may require comparative blocks, which can result in numerous spinal injections.
This is problematic; there is no good way to make the diagnosis before doing more rational, conservative treatment, he said.
"I think that there are probably better things than doing 30 injections into someone’s spine to establish a diagnosis," he said.
In fact, treatment for facet joint OA generally involves physical activity.
"You don’t want to push these people to their limits, but certainly it is important to have them move and to have them keep the strength in their spine," he said.
In the absence of good studies evaluating noninterventional therapy for confirmed facet joint pain, treatment is generally based on findings in patients with chronic nonspecific low back pain and knee OA, and there is evidence in both of those settings that suggest exercise is helpful for increasing strength and decreasing pain and disability.
A Cochrane review showed that exercise therapy provides mild to moderate benefit. Additional studies have suggested that early referral to physical therapy results in modest improvement in function at 12 months in older adults, suggesting physical therapy provides longer-term results than many other interventions for low back pain, which tend to provide only short-term relief, he noted.
Furthermore, patients who have physical therapy tend to require fewer interventions. Dr. Gellhorn found in a recent study that physical therapy in a Medicare population with low back pain was associated with fewer lumbar injections, physician office visits, and lumbar surgeries.
"So it’s very reasonable to send your patients with facet joint OA to PT," he said.
Other treatments that may have some benefit if physical activity is inadequate include intra-articular steroid injections and radiofrequency denervation.
In studies that used SPECT for inclusion criteria, intra-articular injections were better than medial branch blocks at 3 months, and were more effective at 1 month and 3 months than were injections used in studies that did not use SPECT for inclusion, he said.
Injections were not useful in studies that used physical examination or diagnostic block for inclusion.
"So if you’re basing it on metabolic activity, you’re likely to have a good outcome from your injection," he said.
Radiofrequency denervation tends to work better in the cervical spine than in the lumbar spine, but it is difficult to justify in practice because it requires medial branch block, or double or even triple block to optimize success, and because it is associated with a number of potential complications, such as loss of innervation to the multifidus muscles.