Biomechanical properties of paraspinal muscles and their influence on spinal loading : an experimental and computational investigation
Bibliographic record
Abstract
Adult spinal deformity (ASD) is prevalent among ~30% of the population above 65 years old. While decreased back extensor strength in the form of muscle weakness/dysfunction is well-documented for these patients, it is unclear what muscle properties lead to such decreased strength. The overall goal of this research project was to investigate if biomechanical properties of the paraspinal muscles are different in ASD patients; and whether those differences could influence spinal loading and be associated with the initiation/progression of ASD. To achieve this goal, four studies were conducted. The first study examined the effect of spinal level on elastic modulus, slack sarcomere length, and collagen deposition in paraspinal muscles of 13 rats revealing independence of those properties on the spinal level. In the second study, the influence of the size of single muscle fibers and fiber bundles on elastic modulus was investigated for both rodents and humans. Smaller fibers and fiber bundles manifested larger elastic moduli, highlighting the necessity of aiming for consistent bundle sizes for passive property measurement. For the third study, ethical and technical requirements for intraoperative human muscle biopsy acquisition were addressed and paraspinal muscle biopsies were collected from nine ASD patients. Although patient-recruitment halted because of COVID-19 and thus the small number of patients did not allow performing a statistical comparison between the patients, thought-provoking observations were made. In situ- and slack sarcomere lengths had large variations; several fiber bundles exhibited substantially high stiffnesses, and histopathological analysis unveiled a variety of extracellular and intracellular case-specific abnormalities. The variations observed for the biomechanical properties were input to an enhanced musculoskeletal model of the thoracolumbar spine, which predicted increases in the intradiscal pressures by several orders of magnitudes in some cases. This fourth study highlighted the importance of biomechanical properties along with the muscle force-length curve to the spinal forces. The entire thesis demonstrated that biomechanical properties of paraspinal muscles do vary among ASD patients and this can dramatically influence the spinal loads. Therefore, future experimental and computational studies should be conducted to provide further insight on the potential role of these properties in the initiation/progression of ASD.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".