A follow-up MRI study 1 of how non-specific lower back pain (LBP) patients responded to spinal manipulative therapy (SMT) showed that, while there were no significant differences in spinal degenerative features across responding and non-responding groups studied, the non-responding patient group appeared to have more severe degenerative features and lower baseline ADC values in their MRI scans than those who responded well to SMT. The study indicates that patients who respond well to SMT have fewer degenerative changes in posterior joints and disc diffusion than those who do not respond positively to SMT. The study suggests that treatment for patients with extreme degenerative changes should be tailored to address their LBP, as SMT may not provide a desired outcome for their condition.
What’s at Stake?
LBP –in particular, non-specific LBP—is one of the leading causes of disability and lost income potential across the world. Though SMT has been proven an effective form of treatment for many patients with non-specific forms of LBP, not all patients respond favorably to spinal adjustments or report satisfaction with their levels of pain relief and physical comfort, post-SMT. While many patients demonstrate measurable clinical improvements after 1 -3 SMT treatments, a subset of non-specific LBP patients do not respond to SMT. A previous study demonstrated a reduction in spinal stiffness, improvements in modality and an increase in lumbar multifidus contraction, and water diffusion at the L4-L5 disc level in a group of SMT responders after one week of treatment, while these benefits did not manifest in a group of non-responders or a control group. The current study was conducted to use MRI to look for significant differences between responders and non-responders that might account for the discrepancy in SMT outcomes.
A secondary analysis of the original non-randomized clinical trial involving subjects between 18 and 60 years of age who experienced non-specific LBP with an intensity of at least 2 on an 11-point scale and at least 20 percent on the modified Oswestry Disability Index (mODI) was conducted. Exclusion criteria included prior lumbar surgery, scoliosis, pregnancy, SMT within the past four weeks, and spinal tumors, fractures, or any issues that might exclude the subject from MRI scanning.
The 32 subjects attended three sessions—the first, with an MRI scan and standardized SMT, the second, with SMT only, and the third, where an evaluation of their mODI score, spinal stiffness, and multifidus function was analyzed. No SMT was performed at the last session. Subjects with greater than 30 percent improvement at the third session within one week were deemed “responders.” Those with less than 30 percent improvement were considered “non-responders.”
MRI findings were graded on a 4-point scale of joint degeneration and clinical value. Considerations included space between joints, osteophyte presence, hypertrophy of the articular process, subchondral cysts, and subarticular erosion. Other spinal irregularities were also analyzed and graded on subsequent rating scales.
Baseline spinal structure demographics were similar across the board for all subject groups. A total of 15 subjects were labeled as “responders” based on the mODI scores, and 17 were considered to be “non-responders” to the SMT. The non-responders had more disc degeneration in their facet joints, as seen in the MRI scans. IVD and MC grading was similar in both groups. There was a higher prevalence of degeneration in the L4-L5 and L5-S1 levels in those with disc degeneration. Modic endplate changes were more prevalent in the non-responder group, at 58 percent (46.7 percent in the responder group).
Baseline ADC mean measurements and post-SMT disc diffusion responses varied between the two groups, with the lower scores of non-responders suggestive of higher rates of L4-L5 disc degeneration—a potential source of pre-and-post-treatment pain. The limited mobility of the degenerated discs could also be a factor in the non-responder group’s outcomes. The authors of the review suggest further studies with a larger sample size be conducted in the future to investigate the relationship between spinal degeneration, SMT response, and lower back pain.
The review did find beneficial post-SMT ADC level increases in the group of responders with LBP that suggests the therapeutic value of spinal manipulation in improving disc diffusion in and around painful spinal segments. However, 26 percent of the responders with LBP had no significant change in the ADC levels, so the beneficial effects of SMT may have more to do with mechanical or neurophysiological alterations, rather than diffusion.
Pathologies that are not biomechanical in nature, including bone inflammation, are unlikely to respond to SMT, according to the study. The findings highlight that non-specific LBP is treatment-specific, since its origin may be caused by a number of different conditions. Therefore, the review’s authors caution against using a single SMT approach in treating all non-specific LBP.