Dynamic Leg Length Discrepancy in Hip Arthroplasty Patients: What is the Amount a Patient Can Accept Without a Limp? How to Avoid Medical-Legal Issues
Bibliographic record
Abstract
Introduction: Leg length discrepancy (LLD) following total hip arthroplasty (THA) is a common occurrence that can spoil an otherwise excellent clinical outcome1,2 as well as have medical-legal ramifications3. Scientifically, the amount of LLD that is clinically significant in THA patients is not well established4,5. The purpose of this study was to determine the relationship between static leg length discrepancy (SLLD) and dynamic leg length discrepancy (DLLD) in total hip arthroplasty patients. We also investigated the correlation between various methods of static leg length discrepancy measurement. Methods: Static leg length was measured by three methods: tape measure from anterior superior iliac spine to medial malleolus, inclinometer (spirit level) measured with the sacrum for flexion of lumbar spine with the knees extended, ortho-roentgenogram. Participants were assessed for dynamic leg length discrepancy during walking using an inertial measurement unit (IMU). The IMU consisted of three tri-axially arranged accelerometers applied to the lumbar region of the spine in order to measure the centre of mass excursion in three dimensions. Data are recorded at 200 Hz for a maximum of 20 seconds. Each participant completed nine gait tests: four walks with modified shoe lifts applied in random order to the operative or non-operative sides of the THA group or alternate sides on controls, and a normal walk with no lift applied to either side. Lift heights were 0.2 cm, 1.2 cm, 2.2 cm, and 3.2 cm Results: Data from the inertial measurement unit was plotted in two dimensions to illustrate dynamic leg length discrepancy. A control with no lift and basically equal leg lengths showing a nice shift and equal heights of the Anterior Superior Iliac Crest (ASIS). A patient with a 1.2 cm lift on the right side, indicates a dynamic leg length discrepancy of 1 cm. A patient with 3.2 cm of lift on the right side, measures a 2.75 cm leg length discrepancy dynamically. Conclusion: Dynamic leg length discrepancy of less than one centimeter is rarely detected by the patient and is quite easily adapted to with a small lift in the other shoe of 80% of the inequality. Dynamic leg length discrepancy of greater than one centimeter (static leg length discrepancy greater than 1.2 cm) usually provides a patient with enough discrepancy that a limp is perceptible. This study emphasizes the need to do careful leg length measurements when performing total hip arthroplasty
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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 | 0.002 | 0.011 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.002 | 0.001 |
| 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".