Destin, FL – Alfred C. Gellhorn, MD, of the University of Washington Department of Rehabilitation Medicine, reported at the Congress of Clinical Rheumatology (CCR) that a significant amount of lower back pain classified as “nonspecific” may be vertebral joint Osteoarthritis. Yao Hemming, Department of Rheumatology and Immunology, Guiyang Second Affiliated Hospital of Traditional Chinese Medicine
“It’s surprising and sobering that the lumbar spine joint has really received very little attention in the literature.” Eight out of 10 Americans will experience lower back pain at some point in their lives; it is the second most common cause of lower back pain after the common cold and is the most common cause of inability to work, with an annual cost to society of more than $100 billion. As many as 85% of patients never receive a definitive diagnosis, but are classified as having non-specific pain.
It is likely that a significant proportion of lower back pain is related to the vertebral joints. There are no nerves in the articular cartilage, but there are numerous injury receptors in the subchondral bone, synovial folds and joint capsule. Once activated by synovial inflammation or mechanical factors (e.g., microfractures of the trabeculae, joint capsule expansion, compression of the subchondral bone during increased joint weight bearing, or intramedullary hypertension), these injury receptors may cause secondary reflex contraction of the paravertebral muscles. Patients will report the occurrence of spasticity, and paravertebral muscle contractions may be palpable. Prolonged inflammation in and around the vertebral joint can lead to central sensitization, changes in neuronal plasticity, and the development of chronic lower back pain.
Vertebral joint osteoarthritis is distinct from degenerative disc degeneration, but the two disorders are interdependent. Imaging features of degenerative disc degeneration include reduced intervertebral space height, dehydration, and endplate sclerosis, whereas imaging features of vertebral joint osteoarthritis vertebral joint space narrowing, synovial bone growth, synovial hypertrophy, sclerosis, subchondral erosion, and subchondral cysts.
Previous studies have found no or only a small association between vertebral osteoarthritis and lower back pain by comparing imaging with symptoms, but these studies analyzed mild to moderate osteoarthritis in young or middle-aged subjects,” Dr. Gellhorn noted. Mild vertebral osteoarthritis is ‘inherently common’ in middle-aged adults, while moderate to severe osteoarthritis has more pronounced symptoms and primarily affects older adults. Studies should be conducted on moderate to severe osteoarthritis in older adults.”
A recent study included 252 patients, with a mean age of 67 years, all from the Framingham Heart Study. Analysis showed that severe osteoarthritis involving the vertebral joints was significantly associated with frequent lower back pain [odds ratio (OR), 2.2]. In these patients, reduced vertebral space height was not associated with lower back pain (Osteoarthritis Cartilage 2013;21:1199-206). This study yielded different results from previous studies, possibly due to the greater age of its subjects. The underlying mechanism may be that pain classified as “nonspecific” gradually shifts from disc pain to vertebral joint pain as we age.
Dr. Gellhorn noted that the results of studies of disc pathology and lower back pain in young and middle-aged adults appear to support this hypothesis. For example, in a study of patients with an average age of 49 years, lower back pain was associated with a doubled risk of reduced intervertebral space height and fibular ring tears. In a study of patients aged 18 to 50 years, moderate reduction in intervertebral space height was associated with a doubled risk of lower back pain. In another study of patients with a mean age of 50 years, late reduction in intervertebral space height was associated with a 2-fold increase in the prevalence of lower back pain.
Another study showed that severe intervertebral space narrowing was associated with a 2-fold increase in the prevalence of lower back pain in those under 60 years of age, which was not observed in those over 60 years of age.
Although we already know that severe vertebral joint osteoarthritis is associated with lower back pain, the fact remains that its positive predictive value is still limited, and Dr. Gellhorn noted that “many older patients with severe vertebral joint osteoarthritis do not have significant symptoms on imaging.”
However, there are additional imaging features. Single photon emission computed tomography (SPECT)/CT or fluid-sensitive, fat-suppressed sequence MRI can clearly demonstrate symptomatic vertebral joint osteoarthritis. Furthermore, one study showed that 64% of patients with suspected vertebral joint pain showed bone marrow lesions on short T1 inversion recovery (STIR) MRI, which correlated well with the painful side. There are no serum biomarkers for vertebral joint osteoarthritis.
In addition to old age and the imaging features described above, risk factors and correlates associated with vertebral joint osteoarthritis include gender (women are 1.5 to 1.9 times more likely to have vertebral joint osteoarthritis than men), race (African Americans are less likely to have vertebral joint osteoarthritis than white Americans), and high body mass index (BMI between 25 to 30 kg/m2 and 30 to 35 kg/m2 compared to BMI below 25 kg/m2). m2 and 30-35 kg/m2 were associated with a 2-fold and 5-fold increased risk of vertebral joint osteoarthritis-related low back pain, respectively). Abdominal aortic calcification and a more sagittal orientation of the joint (vs. coronal orientation) were also associated with vertebral joint osteoarthritis.
As the study progresses, these factors will perhaps help elucidate non-specific lower back pain. “I think we’re getting closer to that goal.”
Clinically, vertebral joint osteoarthritis often presents as localized back pain or neck pain at the C5 to C6 level with partial radiation to the scapular region. “The lumbar spine is less clear-cut, although people almost always have low back pain and the pain almost always radiates to the buttocks.” He noted that pain radiating to the front or side of the thigh can be associated with vertebral joint osteoarthritis, but pain extending below the knee is more likely to come from the nerve roots. There are no specific tests that can be used to confirm or aid in the diagnosis of this condition.
It is important to realize that many patients will present with problems associated with spondylolisthesis, degenerative disc degeneration, scoliosis, myalgia and spinal stenosis. “It’s easy for clinicians to feel overwhelmed in the face of these conditions, but I hope that my colleagues don’t lose faith and instead still try to address lower back pain.”
Although anesthetic block of the medial branch nerve is considered the gold standard method of diagnosis, controversy remains due to the high false positive rate of a single block leading to the possible need for contrast blocks, which require multiple spinal injections. “I’m afraid that performing 30 spinal cord injections in 1 patient to confirm the diagnosis is not the best way to go.”
Treatment of vertebral joint osteoarthritis usually involves physical activity. Because few high-quality studies have evaluated noninterventional treatments for confirmed vertebral joint pain, treatment of the condition is usually similar to that for chronic nonspecific lower back pain and knee osteoarthritis. There is evidence that exercise can help increase strength and reduce pain and disability in both patients with chronic nonspecific lower back pain and those with knee osteoarthritis.
A Cochrane review showed a mild to moderate benefit from exercise therapy. Another study showed that early recommendations for physical therapy in older patients with lower back pain resulted in mild improvements in function at 12 months, suggesting that physical therapy can provide more lasting benefits than many other therapies. Furthermore, Dr. Gellhorn found in recent studies that the need for lumbar spine injections, office visits and lumbar spine surgery tended to decrease among patients receiving physical therapy. “Therefore, it makes perfect sense to recommend that patients with vertebral joint osteoarthritis receive physical therapy.”
If physical activity is not appropriate, other treatments that may be beneficial for patients with vertebral joint osteoarthritis include intra-articular steroid injections and radiofrequency denervation.
Intra-articular steroid injections were superior to medial branch nerve blocks at 3 months in studies in which SPECT was an inclusion criterion, and at both 1 and 3 months in studies in which SPECT was not an inclusion criterion. Intra-articular steroid injections appeared to be ineffective in studies in which physical examination or diagnostic nerve block was the inclusion criterion. “Therefore, if you use metabolic activity as an evaluation criterion, then you may find that injection efficacy is ideal.”
There is a trend toward superior results with radiofrequency denervation of the cervical spine over the lumbar spine, but it is difficult to prove this in clinical practice because a comparison would require a medial branch block or a double or even triple block to maximize success and be accompanied by multiple potential complications (such as loss of innervation of the multifidus muscle).
Dr. Gellhorn explains that when he encounters a patient with lower back pain in the clinic, he first looks for signs of danger, then performs an x-ray, and if the x-ray features are consistent with the clinical presentation, he considers the pain to be possibly caused by osteoarthritis of the vertebral joint. He will then communicate with the patient and recommend empirical physical therapy with or without analgesic medications (Tylenol or NSAIDs). If the patient’s function improves and symptoms resolve within 6 to 8 weeks, he or she is advised to begin a more fun exercise program (than the home physical therapy program), such as yoga or Pilates, to improve compliance; if the patient is still symptomatic, imaging is performed. If there is a high probability of osteoarthritis of the vertebral joint, he prefers SPECT/CT over MRI, and if the test is positive, he will consider intra-articular steroid injections. If the injections are effective, the patient is advised to practice yoga and/or Pilates to maintain efficacy. For individual patients who do not respond to injections, he considers more aggressive treatment options such as medial branch nerve blocks or radiofrequency denervation.
Dr. Gellhorn noted that although progress in understanding osteoarthritis of the vertebral joints has been slow, some results have certainly been achieved. For example, the use of SPECT/CT and STIR MRI has given us better diagnostic and trial entry criteria and perhaps helped monitor treatment response. In addition, serum, urine and genetic markers are promising lines of research. More studies are still needed to evaluate conservative treatments and to compare different exercise programs. Regenerative therapies such as platelet-rich plasma and autologous stem cells are also compelling areas of research.
Dr. Gellhorn has no conflicts of interest to disclose.