Factors related to the inability of individuals with low back pain to improve with a spinal manipulation

BACKGROUND AND PURPOSE: Although spinal manipulation is one of the few interventions for low back pain supported by evidence, it appears to be underutilized by physical therapists, possibly due to therapists' concerns that a patient may not benefit from the intervention. The purpose of this study was to identify factors that are associated with an inability to benefit from manipulation. SUBJECTS: Seventy-five people with nonradicular low back pain (mean age=37.6 years, SD=10.6, range=19-59; mean duration of symptoms=41.7 days, SD=54.7, range=1-252) participated. METHODS: Subjects underwent a standardized examination that included history-taking; self-reports of pain, disability, and fear-avoidance beliefs; measurement of lumbar and hip range of motion; and use of various tests. All subjects received a spinal manipulation intervention for a maximum of 2 sessions. Subjects who did not show greater than 5 points of improvement on the modified Oswestry Low Back Pain Disability Questionnaire were considered to have shown no improvement with the manipulation. Baseline variables were tested for univariate relationship with the outcome of the manipulation. Variables showing a univariate relationship were entered into a logistic regression equation, and adjusted odds ratios were calculated. RESULTS: Twenty subjects (28%) did not improve with manipulation. Six variables were identified as being related to inability to improve with manipulation: longer symptom duration, having symptoms in the buttock or leg, absence of lumbar hypomobility, less hip rotation range of motion, less discrepancy in left-to-right hip medial rotation range of motion, and a negative Gaenslen sign. The resulting logistic regression model explained 63% of the variance in manipulation outcome. DISCUSSION AND CONCLUSION: The majority of subjects improved with manipulation. Baseline variables could be identified that were predictive of which subjects would not improve.