Browsing by Author "Roby, Matias"

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    Effects of Elbow Crutch Locomotion on Gluteus Medius Activation During Stair Ascending
    (2022) De La Fuente Cancino, Carlos Ignacio; Neira, Alejandro; Torres, Gustavo; Silvestre, Rony; Roby, Matias; Yañez, Roberto; Herrera, Sofia; Martabit, Virgina; McKay, Isabel; Carpes, Felipe P.
    Crutches can help with the locomotion of people with walking disorders or functional limitations. However, little is known about hip muscle activation during stair ascending using different crutch locomotion patterns in people without disorders and limitations. Thus, we determined the acute effects of elbow crutch locomotion on gluteus medius (GM) activity during stair ascending. This comparative analytic cross-sectional study enrolled ten healthy men (22.0 ± 0.47 years). Participants climbed up the stairs with elbow crutches using one or two crutches, with ipsilateral or contralateral use, and after loading or unloading a limb. EMG signals were recorded from anterior, middle, and posterior portions of the GM and compared between the crutch conditions. The Kruskal–Wallis test and Dunn’s multiple comparison test were performed (α= 5%). The activation of the GM increased with the ipsilateral use of crutches, with two crutches and three points, and when all the load depended only on one limb. GM activation decreased with contralateral use and in the unload limb. In conclusion, ascending stairs with elbow crutches alters the GM activation. The more critical factors were choosing the crutches’ lateral use, the number of crutches, and if the limb is loaded or unloaded while ascending the stairs. Our findings can be helpful to increase or decrease the GM activation for those who use or will use crutches.
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    Exploratory Anterior Cruciate Ligament Graft Stress during Medial Knee Rotation with and without Iliotibial Band-Intermuscular Septum Lateral Extra-Articular Tenodesis for Transtibial and Anteromedial Femoral Tunnels
    (2024) Yanez, Roberto; Silvestre, Rony; Roby, Matias; Neira, Alejandro; Madera, Samuel; de la Fuente, Carlos
    Traditional lateral extra-articular tenodesis (LET) using fixation elements constrains medial knee rotation laxity after anterior cruciate ligament reconstruction (ACLr). However, the mechanical behavior of an LET made with an iliotibial band-intermuscular septum is unknown using different anterior cruciate ligament (ACL) reconstruction drillings and would be crucial for constraining the rotatory components of direction change movements. Thus, this study aimed to explore the maximum principal stresses and their distribution in grafts during medial knee rotation with and without iliotibial band-intermuscular septum lateral extra-articular tenodesis for the transtibial technique (TT), hybrid transtibial technique (HTT), and anteromedial portal technique (AM) in single-bundle ACLr. The maximum von Mises principal stresses and their distribution under medial knee rotation were described using a finite element model generated from a healthy knee. LET with HTT, TT, and AM decreases stress by 97%, 93%, and 86% during medial rotation compared to each technique without LET, respectively. The stress concentration for the AM portal and TT techniques was located at the femoral tunnel, and for HTT with LET, it was located across the distal thirds of the anterior aspect of the graft. In conclusion, the HTT with LET diminishes graft stress more than the HTT, TT, and AM without LET, and the TT and AM with LET during medial knee rotation. The AM portal, HTT, and TT techniques without LET show higher stress concentration patterns at the femoral tunnel, establishing a biomechanical risk of femoral tunnel enlargement when LET is not performed.
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    Multiclass Support Vector Machine improves the Pivot-shift grading from Gerdy's acceleration resultant prior to the acute Anterior Cruciate Ligament surgery
    (2023) Yanez-Diaz, Roberto; Roby, Matias; Silvestre, Rony; Zamorano, Hector; Vergara, Francisco; Sandoval, Carlos; Neira, Alejandro; Yanez-Rojo, Cristobal; De la Fuente, Carlos
    Introduction: Rotatory laxity acceleration still lacks objective classification due to interval grading superposition, resulting in a biased pivot shift grading prior to the Anterior Cruciate Ligament (ACL) reconstruction. However, data analysis might help improve data grading in the operative room. Therefore, we described the improvement of the pivot-shift categorization in Gerdy's acceleration under anesthesia prior to ACL surgery using a support vector machine (SVM) classification, surgeon, and literature reference. Methods: Seventy-five patients (aged 30.3 +/- 10.2 years, and IKDC 52.0 +/- 16.5 points) with acute ACL rupture under anesthesia prior to ACL surgery were analyzed. Patients were graded with pivot-shift sign glide ( + ), clunk ( ++ ), and ( +++ ) gross by senior orthopedic surgeons. At the same time, the tri-axial tibial plateau acceleration was measured. Categorical data were statistically described, and the accelerometry and categorical data were associated ( alpha = 5%). A multiclass SVM kernel with the best accuracy trained by orthopedic surgeons and assisted from literature for missing data was compared with experienced surgeons and literature interval grading. The cubic SVM classifier achieved the best grading.Results: The intra-group proportions were different for each grading in the three compared strategies ( p < 0.001). The inter-group proportions were different for all comparisons ( p < 0.001). There were significant ( p < 0.001) associations (Tau: 0.69, -0.28, and -0.50) between the surgeon and SVM, the surgeon and interval grading, and the interval and SVM, respectively.Conclusion: The multiclass SVM classifier improves the acceleration categorization of the ( + ), ( ++ ), and ( +++ ) pivot shift sign prior to the ACL surgery in agreement with surgeon criteria.(c) 2023 Elsevier Ltd. All rights reserved.
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    Preseason multiple biomechanics testing and dimension reduction for injury risk surveillance in elite female soccer athletes: short-communication
    (2023) De la Fuente, Carlos; Silvestre, Rony; Yanez, Roberto; Roby, Matias; Soldan, Macarena; Ferrada, Wilson; Carpes, Felipe P.
    Background Injury risk is regularly assessed during the preseason in susceptible populations like female soccer players. However, multiple outcomes (high-dimensional dataset) derived from multiple testing may make pattern recognition difficult. Thus, dimension reduction and clustering may be useful for improving injury surveillance when results of multiple assessment tools are available. Aim To determine the influence of dimension reduction for pattern recognition followed by clustering on multiple biomechanical injury markers in elite female soccer players during preseason. Methdology We introduced the use of dimension reduction through linear principal component analysis (PCA), non-linear kernel principal component analysis (k-PCA), t-distributed stochastic neighbor embedding (t-sne), and uniform manifold approximation and projection (umap) for injury markers via grid search. Muscle strength, muscle function, jump technique and power, balance, muscle stiffness, exercise tolerance, and running performance were assessed in an elite female soccer team (n = 21) prior to the competitive season. Results As a result, umap facilitated the injury pattern recognition compared to PCA, k-PCA, and t-sne. One of the three patterns was related to a team subgroup with acceptable muscle conditions. In contrast, the other two patterns showed higher injury risk profiles. For our dataset, umap improved injury surveillance through multiple testing characteristics. Conclusion Dimension reduction and clustering techniques present as useful strategies to analyze subgroups of female soccer players who have different risk profiles for injury.