Background
The spine has a complex motor control. Its different stabilization mechanisms through passive, active, and neurological subsystems may result in spinal stiffness. To better understand lumbar spinal motor control, this study aimed to measure the effects of increasing the axial load on spinal stiffness.
Methods
A total of 19 healthy young participants (mean age, 24 ± 2.1 years; 8 males and 11 females) were assessed in an upright standing position. Under different axial loads, the posterior-to-anterior spinal stiffness of the thoracic and lumbar spine was measured. Loads were 0%, 10%, 45%, and 80% of the participant’s body weight.
Results
Data were normally distributed and showed excellent reliability. A repeated-measures analysis of variance with a Greenhouse–Geisser correction showed an effect of the loading condition on the mean spinal stiffness [F (2.6, 744) = 3.456, p < 0.001]. Vertebrae and loading had no interaction [F (2.6, 741) = 0.656, p = 0.559]. Post hoc tests using Bonferroni correction revealed no changes with 10% loading (p = 1.000), and with every additional step of loading, spinal stiffness decreased: 0% or 10–45% loading (p < 0.001), 0% or 10–80% loading (p < 0.001), and 45–80% (p < 0.001).
Conclusion
We conclude that a load of ≥ 45% of the participant’s body weight can lead to changes in the spinal motor control. An axial load of 10% showed no significant changes. Rehabilitation should include high-axial-load exercise if needed in everyday living.
Background: Pain chronicity is considered an important prognostic factor for outcome. Here, it was investigated whether pain duration influences outcome when only chronic patients (pain >3 months) are considered. Secondary aims were to determine, in patients of any pain duration, how much variance in outcome is explained by pain duration and whether pain duration truly predicts outcomes, that is out-of-sample prediction in independent data. Methods: Secondary analysis of a cohort study of neck pain patients. Patients were assessed before start of treatment and at 1-week, 1-, 3-, 6-and 12-month follow-up. Outcomes were patient global impression of change (PGIC) and percent change in patients' perceived pain intensity, rated on a numerical rating scale (NRS). Regression analyses (linear and logistic) and supervised machine learning were used to test the influence of pain duration on PGIC and percent NRS change at 1-week, 1-, 3-, 6-and 12-month follow-up within sample and out-of-sample.Separate analyses were performed for the full sample (n = 720) and for chronic patients (n = 238) only.
Results:No relationship between pain duration and outcome was found for chronic patients only. For the full sample, statistical relationships between pain duration and outcomes were observed at all tested follow-up time points. However, the amount of variance in outcome explained by pain duration was low and no out-of-sample prediction was possible.Conclusions: Pain duration did not emerge as an important predictor of outcome in this database of 720 neck pain patients receiving chiropractic treatment.
Significance statement:The relatively large dataset of neck pain patients challenges the widely accepted wisdom that pain duration is an important predictor of pain outcomes and that very chronic patients might only have a small likelihood of getting better. It is postulated that these results are important for the attitude of the first encounter between healthcare professionals and chronic patients.
Background: Cortical reorganization and its potential pathological significance is increasingly studied in chronic low back pain (CLBP) patients. Yet, detailed cortical maps of the healthy human back are lacking. To better understand cortical changes during the development and maintenance of CLBP, a detailed baseline characterization resulting from sensory thoracolumbar afferent input is needed. To this end, a novel
pneumatic vibrotactile stimulation method was used to stimulate paraspinal sensory afferents while studying their cortical representations in unprecedented detail. Methods: In 30 young healthy participants, vibrotactile stimulations at 20Hz and 80Hz were applied bilaterally at nine locations along the thoracolumbar axis while functional magnetic resonance imaging (fMRI) was performed. A whole-brain searchlight
representational similarity analysis (RSA) in combination with different experimental models of paraspinal afferent input was used to investigate the representational organization of the respective neuronal activation patterns. Results: For 80Hz, the organizational structure of the neuronal activation patterns yielded the best fit for a model based on segmental distances between the stimulated paraspinal locations, located bilaterally in the primary (S1) and secondary somatosensory (S2) cortices. For 20Hz, this observation was restricted to the right S1. Conclusions: fMRI during paraspinal vibrotactile stimulation in combination with RSA is a powerful tool that can be used to establish highly detailed cortical maps of the human back. The current findings constitute a promising basis to further explore cortical reorganization and its potential pathological meaning in CLBP patients.
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