A Biomechanical Comparison of Two Triple-Screw Methods for Femoral Neck Fracture Fixation in a Synthetic Bone Model
Bibliographic record
Abstract
BACKGROUND: Fixation of femoral neck fractures is often accomplished by several screws inserted along the neck axis. Alignment and number of screws remain at the discretion of the surgeon. Two fracture repair methods were compared. METHODS: Sixteen large, left, adult, synthetic femurs, known as Third Generation Composite Femurs (Pacific Research Laboratories, Vashon, WA), were osteotomized with a transverse cut perpendicular to the neck axis. Fractures were reduced and repaired using method 1 (n = 8) or method 2 (n = 8) cannulated cancellous screw methods. Method 1 screws were inserted parallel in an upside-down triangle configuration and abutted against the cortical walls inferiorly, anteriorly, and posteriorly. Method 2 screws were placed adjacent to one another as often done clinically. Femoral shafts were positioned in a nonclinical vertical orientation to obtain conservative "lower bound" measurements. Specimens were tested for torsional and axial stiffness using subclinical loads followed by axial failure tests. RESULTS: Method 1 showed statistically higher values compared with method 2 for torsional stiffness (9.9 vs. 7.9 Nm/deg, method 1/method 2 ratio = 1.25, p = 0.018), axial stiffness (1469.0 vs. 1278.1 N/mm, method 1/method 2 ratio = 1.15, p = 0.023), and axial failure load (3493.5 vs. 2863.5 N, method 1/method 2 ratio = 1.22, p = 0.000). However, there were no statistical differences in axial failure displacement (10.9 vs. 16.9 mm, method 1/method 2 ratio = 0.64, p = 0.101) or axial failure energy (29.9 vs. 35.9 J, method 1/method 2 ratio = 0.83, p = 0.453). For both methods, femoral heads move distally while screw shafts cut through the spongy cancellous matrix of the femoral neck in knife-like fashion. CONCLUSIONS: Method 1 was more mechanically stable than method 2 in femoral neck fracture fixation as detected by three of five biomechanical measurements and equivalent to method 2 for two of five biomechanical measurements.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| 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 | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".