Morphologie scapulo-humérale et luxation antérieure d'épaule (étude rétrospective mono centrique anatomo-radiologique chez 61 patients)

Résumé françaisDIJON-BU Médecine Pharmacie (212312103) / SudocSudocFranceF

Do trapeziometacarpal prosthesis provide better metacarpophalangeal stability than trapeziectomy and ligamentoplasty?

International audienceBACKGROUND:No surgical management is better than another regarding functional recovery for trapeziometacarpal joint osteoarthritis. Metacarpophalangeal (MCP) hyperextension, directly due to the shortening of thumb height, appears to be a factor of poor prognosis.HYPOTHESIS:MCP hyperextension can be corrected by implantation of a trapeziometacarpal prosthesis (TMP), as opposed to trapeziectomy and ligamentoplasty (TL), and pinch strength is greater with TMP in this indication.MATERIAL AND METHODS:Sixty-nine patients (41 TMP and 28 TL) were retrospectively evaluated. The following were evaluated: pain, mobility of the metacarpophalangeal joints, palmar grip and pinch strength. Thumb height was measured on radiographs as a post/preoperative ratio.RESULTS:The mean follow-up was 20 months (6-38). The TMP group showed greater reduction of the metacarpophalangeal hyperextension in all hyperextension groups, especially hypertension >30°, compared with TL. The TMP group provided significant greater pinch strength in all the subgroups with preoperative MCP hyperextension. Patient with postoperative MCP hyperextension had a significant lower grip and pinch strength compared with patient without MCP hyperextension. Radiographic analysis showed that thumb height changes were related to the degree of preoperative hyperextension. Postoperatively, patients with postoperative MCP hyperextension had a significant lower thumb height than patient without MCP hyperextension.DISCUSSION:Metacarpophalangeal hyperextension appears to be a factor of poor prognosis for surgical treatment of trapeziometacarpal osteoarthritis when it is not managed. TMP provides better metacarpophalangeal stabilization by restoring thumb length and would avoid surgery on the metacarpophalangeal joint. TMP may be recommended in patients having symptomatic trapeziometacarpal joint osteoarthritis and MCP joint hyperextension.LEVEL OF EVIDENCE:III, retrospective observational case control study

Linear relationship between lateralization of the bicipital groove and humeral retroversion and its link with the biepicondylar humeral line. Anatomical study of seventy cadaveric humerus scans

International audienceIntroduction Morphological studies of the humerus have shown that the position of the bicipital groove varies with the individual and the retroversion of the humeral head. Depending on the authors, these two parameters are independent or associated. This study evaluated the relationship between the humeral head axis and its retroversion and the bicipital groove relative to the humeral biepicondylar line.Materials and methods Seventy cadaveric humeri were scanned to obtain 3D reconstructions. Views of the 3D reconstruction from above showed the bicondylar line, the bicipital groove and the humeral head on a single image. After measuring the humeral retroversion angle and the bicipital groove angle relative to the bicondylar line, we assessed the relationship between these two angles with Pearson's correlation coefficient.Results Pearson's correlation coefficient indicated a significant linear correlation between the angle of the groove and the angle of humeral retroversion based on the 70 cadaveric humeral bones (the p-value was 7.5(10) (7), the correlation coefficient was -0.5515, and the 95% confidence interval was (-0.6962; -0.3636)). Our study thus demonstrates that the less lateralized the bicipital groove is, the greater the humeral retroversion will be.Conclusion We demonstrated a linear relationship between humeral head retroversion and bicipital groove lateralization. Within our reliability interval, this relationship can be used in clinical practice to evaluate retroversion without resorting to CT of the entire humerus

Determination of a new computed tomography method for measuring the glenoid version and comparing with a reference method. Radio-anatomical and retrospective study

International audiencePurpose In the literature, there are several techniques for measuring the glenoidal version of the scapula. The superiority of the scannographic measurement over the standard radiologic measures seems evident. The main problems are the evaluation and the reproducibility of these methods, which are dependent on the quality of the CT scan and the orientation of its sections. We pinpoint a simple method of the "scapular triangle", the reliability of which deserves special consideration. The aim of this study is to report a simple and reproducible computed tomography method to measure the glenoidal version.Methods Thrity-one shoulder CT scans, performed on patients attending the emergency department of the University Hospital of Dijon between January 2012 and April 2013 for shoulder trauma, were evaluated retrospectively. The CT scan must include the entire body of scapula to allow measurements to be made with both methods: the conventional method of Friedman and our new method of the "scapular triangle". Two independent operators performed inter-observer and intra-observer reproducibility. We compared both techniques with Pearson's test.Result Pearson's test showed a trend line according to a linear correlation between the two methods with a p value of 7.791(-10) and a correlation coefficient of 0.85 with the 95 % confidence interval (0.7213; 0.929).Conclusion The method of the "scapular triangle" is easily applicable on most sections of the CT scan of scapula whether or not it takes the whole body. It is more reliable and reproducible and could be used by any radiologist

Multiple Giant-Magnetoresistance Sensors Controlled by Additive Dipolar Coupling

Vertical packaging of multiple giant magnetoresistance (multi-GMR) stacks is a very interesting noise reduction strategy for local magnetic sensor measurements, which has not been reported experimentally so far. Here, we fabricate multi-GMR sensors (up to 12 repetitions) that maintain a good GMR ratio, linearity, and low roughness. From magnetotransport measurements, two different resistance responses are observed with a crossover at around five GMR repetitions: steplike (N < 5) and linear (N ≥ 5) behavior, respectively. With the help of micromagnetic simulations, we analyze, in detail, the two main magnetic mechanisms: the Néel coupling distribution induced by the roughness propagation and the additive dipolar coupling between the N free layers. Furthermore, we correlate the dipolar coupling mechanism, which is controlled by the number of GMRs (N) and lateral dimensions (width), to the sensor performance (sensitivity, noise, and detectivity); this is in good agreement with analytical theory. The noise roughly decreases in multi-GMRs as 1/√N in both regimes (low-frequency 1/f and thermal noise). The sensitivity is even more strongly reduced, scaling as N^−1, in the strong dipolar regime (narrow devices), while converging to a constant value in the weak dipolar regime (wide devices). Interestingly, they are more robust against undesirable random telegraphic noise than single GMRs at high voltages, and the linearity can be extended towards a much larger magnetic field range, without dealing with the size and reduction of the GMR ratio. Finally, we identify the optimal conditions for which multi-GMRs exhibit lower magnetic field detectivity than that of single GMRs: wide devices operating in the thermal regime, where much higher voltage can be applied without generating remarkable magnetic noise. These results open the path towards spintronics sensors connected and coupled in three dimensions with reduced noise, compact footprint, and mainly tuned by the dipolar coupling

Highly energetic rockfalls: back analysis of the 2015 event from the Mel de la Niva, Switzerland

International audienceProcess-based rockfall simulation models attempt to better emulate rockfall dynamics to different degrees. As no model is perfect, their development is often accompanied and validated by the valuable collection of rockfall databases covering a range of site geometries, rock masses, velocities, and related energies that the models are designed for. Additionally, such rockfall data can serve as a base for assessing the model's sensitivity to different parameters, evaluating their predictability and helping calibrate the model's parameters from back calculation and analyses. As the involved rock volumes/masses increase, the complexity of conducting field-test experiments to build up rockfall databases increases to a point where such experiments become impracticable. To the author's knowledge, none have reconstructed rockfall data in 3D from real events involving block fragments of approximately 500 metric tons. A back analysis of the 2015 Mel de la Niva rockfall event is performed in this paper, contributing to a novel documentation in terms of kinetic energy values, bounce heights, velocities, and 3D lateral deviations of these rare events involving block fragments of approximately 200 m 3. Rockfall simulations are then performed on a "per-impact" basis to illustrate how the reconstructed data from the site can be used to validate results from simulation models