Determination of 3D lumbar spine kinematics by musculoskeletal ultrasound: a preliminary study of validation
Bibliographic record
Abstract
Lumbar spine 3D kinematics determination is currently based on the bone reconstructions from CT-scan and MRI, which are harmful or expensive.Meanwhile, ultrasound is an alternative with less disadvantages, and has been recently used in lumbar spine 3D modelling.This study intends to apply ultrasound-based models to determine the lumbar spine kinematics and compare it with the CT-scan-based result.In this regard, a human lumbar spine was dissected, and technical markers (TM) (Metallic spheres, ⌀ =4.6mm) were glued to the costiforms and spinous processes from L1 to L5, and median and lateral crests of the S1.Then, after fixing the specimen in a neutral position, musculoskeletal ultrasound (MSU) and CT-scan images were collected.Several image processing techniques were applied, and the ultrasound and CT-scan images were separately reconstructed in 3D.In the next step, to visualize the lumbar spine movement, first, different positions including neutral, full and mid positions in flexion-extension, side bending and axial rotation were applied on the specimen and discrete kinematics were defined by collecting the centroid of the TMs, using a 3D digitizer (Hexagon Absolute Arm, error of measurement (mm): 0.008).Afterwards, the locations of the TMsdigitizer were registered to the TMs on the 3D reconstructions using lhpFusionBox software.After having the motion, to determine the intervertebral kinematics, the top of the costiform processes and the most distal points of the spinous processes where virtually palpated on each level to build local anatomical reference system on CT-Scan and MSU 3D models.Z-axis was defined by the costiform processes landmarks, the X-axis was defined as the orthogonal axis to the Z-axis through the spinous process landmarks, and the Y-axis was perpendicular to X and Z axes.Finally, using Euler angles, the intervertebral kinematics were measured and compared for both, the ultrasound and CT-scan based models.The anatomical motion components, including the flexion-extension, side bending and axial rotation, were defined around the Z, X and Y-axes, respectively.
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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 | 0.003 | 0.005 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".