Correlations Between Individuals’ Characteristics and Spinal Stiffness in Individuals With and Without Back Pain: A Combined Analysis of Multiple Data Sets

Posterior to anterior spinal stiffness measured in a sample of 127 secondary care low back pain patients

BACKGROUND

The sensation of spinal stiffness is a commonly reported symptom among back pain patients, with the clinical assessment of spinal stiffness usually being part of the decision-making process when deciding on providing manual treatment of low back pain. While any relationship between spinal stiffness and low back pain is likely to be multifactorial, prior exploration of this relationship has been overly simplistic (e.g., univariate regression analyses). The purpose of this study was to address this gap by taking a broader approach to compare instrumented measures of spinal stiffness to demographic characteristics, pain phenotypes, psychometrics, and spine-related disability in a sample of secondary care low back pain patients using multivariate regression analysis.

METHODS

Instrumented spinal stiffness measures from 127 patients in secondary care were used to calculate terminal and global spinal stiffness scores. A best subset analysis was used to find the subsets of 14 independent variables that most accurately predicted stiffness based on the evaluation of the adjusted R-square, Akaike Information Criteria, and the Bayesian Information Criteria.

FINDINGS

In the resulting multivariate models, sex (p < 0.001) and age (p < 0.001) were the primary determinants of terminal stiffness, while global stiffness was primarily determined by age (p = 0.003) and disability (p = 0.024).

INTERPRETATION

Instrumented measures of spinal stiffness are multifactorial in nature, and future research into this area should make use of multivariate analyses.

A Comparison of Clinical Spinal Mobility Measures to Experimentally Derived Lumbar Spine Passive Stiffness

Spinal stiffness and mobility assessments vary between clinical and research settings, potentially hindering the understanding and treatment of low back pain. A total of 71 healthy participants were evaluated using 2 clinical assessments (posteroanterior spring and passive intervertebral motion) and 2 quantitative measures: lumped mechanical stiffness of the lumbar spine and local tissue stiffness (lumbar erector spinae and supraspinous ligament) measured via myotonometry. The authors hypothesized that clinical, mechanical, and local tissue measures would be correlated, that clinical tests would not alter mechanical stiffness, and that males would demonstrate greater lumbar stiffness than females. Clinical, lumped mechanical, and tissue stiffness were not correlated; however, gradings from the posteroanterior spring and passive intervertebral motion tests were positively correlated with each other. Clinical assessments had no effect on lumped mechanical stiffness. The males had greater lumped mechanical and lumbar erector spinae stiffness compared with the females. The lack of correlation between clinical, tissue, and lumped mechanical measures of spinal stiffness indicates that the use of the term "stiffness" by clinicians may require reevaluation; clinicians should be confident that they are not altering mechanical stiffness of the spine through segmental mobility assessments; and greater resting lumbar erector stiffness in males suggests that sex should be considered in the assessment and treatment of the low back.

The effect on clinical outcomes when targeting spinal manipulation at stiffness or pain sensitivity: a randomized trial

The mechanisms underlying pain relief following spinal manipulative therapy (SMT) are not understood fully although biomechanical and neurophysiological processes have been proposed. As such, we designed this randomized trial to elucidate the contributions of biomechanical and neurophysiological processes. A total of 132 participants with low back pain were randomly assigned to receive SMT at either the lumbar segment measured as the stiffest or the segment measured as having the lowest pain threshold. The primary outcome was patient reported low back pain intensity following treatment. Secondary outcomes were biomechanical stiffness and neurophysiological pressure pain threshold. All outcomes were measured at baseline, after the fourth and final session and at 2-weeks follow-up. Data were analyzed using linear mixed models, and demonstrated that the SMT application site did not influence patient reported low back pain intensity or stiffness. However, a large and significant difference in pressure pain threshold was observed between groups. This study provides support that SMT impacts neurophysiological parameters through a segment-dependent neurological reflex pathway, although this do not seem to be a proxy for improvement. This study was limited by the assumption that the applied treatment was sufficient to impact the primary outcome.

Comparison of Long Segmental Dorsal Stabilization with Complete Versus Restricted Pedicle Screw Cement Augmentation in Unstable Osteoporotic Midthoracic Vertebral Body Fractures: A Biomechanical Study

OBJECTIVE

To compare the construct stability of long-segmental dorsal stabilization in unstable midthoracic osteoporotic fracture situation with complete pedicle screw cement augmentation (ComPSCA) versus restricted pedicle screw cement augmentation (ResPSCA) of the most cranial and caudal pedicle screws.

METHODS

Twelve fresh frozen human cadaveric specimens (Th 4-Th 10) aged 65 years and older were tested in a biomechanical cadaver study. All specimens received a dual-energy X-ray absorption scan and computed tomography scan before testing. Standardized long segmental stabilization was performed. All specimens were matched into pairs. These pairs were randomized into the groups with ComPSCA and ResPSCA. An unstable Th7 fracture was simulated. The maximum load was tested with 6 mm/min until failure or 20 mm had been reached. After testing, a computed tomography scan was performed.

RESULTS

The mean age of the specimens was 87.8 years (range 74-101 years). The mean t score was -3.6 (range -1.2 to -5.3). The mean maximum force in the ResPSCA group was 1600 N (range 1119-1880 N) and 1941 N (1183-3761 N) in the ComPSCA group. No statistically significant differences between both study groups (P = 1.0) could be seen. No signs of screw loosening were visible.

CONCLUSIONS

No statistically significant differences in the maximum loads could be seen. No screw loosening of the non-cemented screws was visible. Thus, the construct stability of long segmental posterior stabilization of an unstable midthoracic fracture using ResPSCA seems to be comparable with ComPSCA under axial compression.

Risk Factors Associated with the Prevalence of Upper and Lower Back Pain in Male Underground Coal Miners in Punjab, Pakistan

There is not enough data available on occupational health and safety issues of underground coal miners in Pakistan. This study focuses on spinal disorders in association with personal and occupational factors. The Nordic Musculoskeletal Questionnaire was used for a cross-sectional study of 260 workers of 20 mines located in four districts of Punjab, Pakistan. Regression models were created for upper back pain and lower back pain of workers whose mean age is 19.8 years (±SD 1.47). Results identify the coal cutting as the most harmful work with odds ratios (ORs) 13.06 (95% confidence interval (CI) 13.7-21.5) for lower back pain and 11.2 (95% CI 3.5-19.4) for upper back pain in participants. Those with greater years of work experience had higher odds of upper back pain (2.4, 95% CI 1.4-3.5) and lower back pain (3.3, 95% CI 1.1-4.4). Number of repetitions (mean value 25.85/minute with ±SD 9.48) are also significant for spinal disorder with ORs of 4.3 (95% CI 3.2-7.4) for lower back and 1.3 (95% CI 1.0-2.4) for upper back. Many other occupational and personal factors are positively associated with the back pain in underground coal mines workers, requiring immediate ergonomic intervention.