DIFFERENCE IN MICROMOTION PREDICTED BY STATIC AND DYNAMIC LOAD CASES
Bibliographic record
Abstract
Introduction Typical failure of cementless total hip arthroplasty is the lack of initial stability. Indeed, presence of motion at the bone implant-interface leads to formation of fibrous tissue that prevents bone ingrowth, which in turn may lead to loosening of the implant. It has been shown that interfacial micromotion around 40 produces partial ingrowth, while micromotion exceeding 150 completely inhibits bone ingrowth. Finite element analyses (FEA) are widely used to evaluate the initial stability of cementless THA in pre-clinical validation. Untill now, most FE models developed to predict initial stability of cementless implants were performed based on static load, by selecting the greatest load at a particular time of the cycle activity, but in fact the hip is exposed to varied load during the activity. The aim of this study is to investigate the difference in the predicted micromotion induced by static, quasi-static and dynamic loading conditions. Materials & Methods Finite element analysis (FEA) was performed on a Profemur®TL implanted into a composite bone. The implant orientation was validated in a previous study [3]. All materials were defined as linear isotropic homogeneous. Static and dynamic FEA was performed for the loading conditions defined by simulating stair-climbing. In the static analysis, the applied resultant force (calculated with a body weight of 836N) were 951N and 2107N to simulate the abductor muscle and the hip joint contact forces, respectively [4]. In the dynamic analysis, the applied resultant force can be seen on Fig. 1. The initial stability was extracted on 54 points (Fig. 2) located on the plasma spray surface by calculating the difference between the final displacement of the prosthesis and the final displacement of the composite bone. Results The mean micromotion predicted with the static loading conditions is 32μm with a maximum of 76μm whereas the maximum micromotion predicted with dynamic loading conditions is 36μm with a maximum of 86μm. Micromotion predicted with dynamic load greater than the micromotion predicted with static load on 35 out of 54 points. In the superior portion of the prosthesis, micromotion predicted with static loading condition is greater on medial posterior and in lateral anterior faces. In the inferior portion, the micromotion Discussion Micromotion predicted by the dynamic loading condition is greater than that predicted with static loading condition. Moreover, 22 points are in the range of 50–150μm (range for partial osseointegration) with dynamic condition, whereas only 16 points are in this range with static condition. On the posterior inferior face, all points are in this range with the dynamic condition, whereas only 2 with static condition. However micromotion predicted at all points either by static or dynamic conditions are lower than 150μm, the threshold value with regard to osseointegration.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 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 | 0.000 |
| 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".