The Experts below are selected from a list of 28170 Experts worldwide ranked by ideXlab platform
Jorg Dickschas - One of the best experts on this subject based on the ideXlab platform.
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correlation of the tibial tuberosity trochlear groove distance with the Q Angle
Knee Surgery Sports Traumatology Arthroscopy, 2016Co-Authors: Jorg Dickschas, Jorg Harre, Thomas Aye, Judith Schwitulla, W StreckeAbstract:Purpose The Q-Angle has been used for years to Quantify lateralization of the patella. The tibial tuberosity–trochlea groove distance (TT–TG distance) was introduced to analyse patellar tracking. Does a significant correlation exist between these two parameters? Do other significant interrelations exist between the Q-Angle/TT–TG distance, torsion of the femur and tibia, the frontal axis, overall leg length, gender, former patellar dislocation, BMI?
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correlation of the tibial tuberosity trochlear groove distance with the Q Angle
Knee Surgery Sports Traumatology Arthroscopy, 2016Co-Authors: Jorg Dickschas, Judith Schwitulla, Jorg Harrer, Thomas Bayer, W StreckerAbstract:The Q-Angle has been used for years to Quantify lateralization of the patella. The tibial tuberosity–trochlea groove distance (TT–TG distance) was introduced to analyse patellar tracking. Does a significant correlation exist between these two parameters? Do other significant interrelations exist between the Q-Angle/TT–TG distance, torsion of the femur and tibia, the frontal axis, overall leg length, gender, former patellar dislocation, BMI? One hundred knees in 55 patients with patellofemoral symptoms were included in a prospective study. All patients underwent clinical examination, including measurement of the Q-Angle. A torsional CT was obtained from all patients. The correlation coefficient was 0.33/0.34 (left/right leg), showing that the TT–TG distance tends to rise in direct ratio to a rising Q-Angle. Thus, a significant correlation was found (p = 0.017). Femoral and tibial torsion had a positive effect on the TT–TG distance, but showed no significant correlation. Leg length had a significant effect on the TT–TG distance (p = 0.04). The frontal axis had a nonsignificant influence on the Q-Angle or TT–TG distance. On average, the Q-Angle in women was 2.38° greater than it was in men, but the difference was not significant. A significant correlation was noted between the Q-Angle and the TT–TG distance. Both depend on various parameters and must be assessed for the analysis of patellofemoral maltracking. The Q-Angle did not differ significantly between men and women; thus, the conclusion is that no different ranges need not be used. Diagnostic study, Level III.
Andrew J. Cosgarea - One of the best experts on this subject based on the ideXlab platform.
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evaluation of a computational model used to predict the patellofemoral contact pressure distribution
Journal of Biomechanics, 2004Co-Authors: John Joseph Elias, Robert Adamson, David R. Wilson, Andrew J. CosgareaAbstract:Abstract One possible cause of patellofemoral pain syndrome is excessive lateral force acting on the patella. Although several treatment methods focus on decreasing the lateral force acting on the patella, the relationship between the lateral force and the patellofemoral contact pressure distribution is unclear. A computational model has been developed to determine how loading variations alter the patellofemoral force and pressure distributions for individual knees. The model allows variation in the Quadriceps and patella tendon forces, and calculates the predicted contact pressure distribution using the discrete element analysis techniQue. To characterize the accuracy of the model, four cadaver knees were flexed on a knee simulator with three initial Q-Angles, while recording the force and pressure distributions with a pressure sensor. A model of each knee was created from CT data. Using the external force applied to the knee, the geometry of the knee, and the Quadriceps origin as input, the pressure distribution was calculated during flexion. Similar trends were noted for the computational and experimental results. The percentage of the total force applied to the lateral cartilage increased with the Q-Angle. The maximum contact pressure increased during flexion. The maximum lateral contact pressure increased with the Q-Angle for three knees. For the other knee, increasing the Q-Angle decreased the maximum lateral pressure. The maximum medial contact pressure decreased as the Q-Angle increased. By characterizing the influence of patellofemoral loading on the force and pressure distributions, the computational model could be used to evaluate treatment methods prescribed for patellofemoral pain.
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in vitro characterization of the relationship between the Q Angle and the lateral component of the Quadriceps force
Proceedings of the Institution of Mechanical Engineers Part H: Journal of Engineering in Medicine, 2004Co-Authors: John J Elias, Andrew J. Cosgarea, Yasayuki Mizuno, Masaru Kumagai, Stephen M Mattessich, Edmund Y S ChaoAbstract:Although the Q-Angle is routinely measured, the relationship between the Q-Angle and the lateral component of the Quadriceps force acting on the patella is unknown. Five cadaver knees were flexed on a knee simulator with a normal Q-Angle, and flexed after increasing and decreasing the Q-Angle by shifting the Quadriceps origin laterally and medially, respectively. The motion of the femur, tibia and patella was tracked from 20 to 90 degrees of flexion using electromagnetic sensors. The motion of landmarks used to Quantify the Q-Angle was tracked to determine the 'dynamic Q-Angle' during flexion. The lateral component of the force applied by the actuator secured to the Quadriceps tendon was also Quantified throughout flexion. Increasing the initial Q-Angle significantly (p < 0.05) increased the dynamic Q-Angle and the lateral force exerted through the Quadriceps tendon throughout flexion. Decreasing the initial Q-Angle significantly decreased the dynamic Q-Angle at 90 degrees of flexion and significantly decreased the lateral force exerted through the Quadriceps tendon from 20 to 40 degrees of flexion. Even though the dynamic Q-Angle changes during flexion, an abnormally large initial Q-Angle can be an indicator of an abnormally large lateral force acting on the patella during flexion.
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Q Angle influences tibiofemoral and patellofemoral kinematics
Journal of Orthopaedic Research, 2001Co-Authors: Yasayuki Mizuno, Andrew J. Cosgarea, Masaru Kumagai, Stephen M Mattessich, John J Elias, Navin Ramrattan, Edmund Y S ChaoAbstract:Numerous surgical procedures have been developed to correct patellar tracking and improve patellofemoral symptoms by altering the Q-Angle (the Angle between the Quadriceps load vector and the patellar tendon load vector). The influence of the Q-Angle on knee kinematics has yet to be specifically Quantified, however. In vitro knee simulation was performed to relate the Q-Angle to tibiofemoral and patellofemoral kinematics. Six cadaver knees were tested by applying simulated hamstrings, Quadriceps and hip loads to induce knee flexion. The knees were tested with a normal alignment, after increasing the Q-Angle and after decreasing the Q-Angle. Increasing the Q-Angle significantly shifted the patella laterally from 20 degrees to 60 degrees of knee flexion, tilted the patella medially from 20 degrees to 80 degrees of flexion, and rotated the patella medially from 20 degrees to 50 degrees of flexion. Decreasing the Q-Angle significantly tilted the patella laterally at 20 degrees and from 50 degrees to 80 degrees of flexion, rotated the tibia externally from 30 degrees to 60 degrees of flexion, and increased the tibiofemoral varus orientation from 40 degrees to 90 degrees of flexion. The results show that an increase in the Q-Angle could lead to lateral patellar dislocation or increased lateral patellofemoral contact pressures. A Q-Angle decrease may not shift the patella medially, but could increase the medial tibiofemoral contact pressure by increasing the varus orientation.
Deiary F Kade - One of the best experts on this subject based on the ideXlab platform.
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the relationship between Quadriceps Angle and tibial tuberosity trochlear groove distance in patients with patellar instability
Knee Surgery Sports Traumatology Arthroscopy, 2012Co-Authors: A D Cooney, Nick Capla, M Newby, A St Clair Gibso, Z Kazi, Deiary F KadeAbstract:Purpose The Quadriceps Angle (Q-Angle) represents the Angle between the vector of action of the Quadriceps and the patellar tendon. An increased Q-Angle has been associated with an increased risk of patellar instability, although there is disagreement on its reliability and validity as it is affected by the position of the limb and contraction of the Quadriceps. Tibial tuberosity–trochlear groove distance (TT–TG) is ascertained by axial CT scanning, with an increased value associated with patellar instability. This study aimed to determine whether the Q-Angle correlates with the TT–TG distance in patients with patellar instability.
David R. Wilson - One of the best experts on this subject based on the ideXlab platform.
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the effects of medialization and anteromedialization of the tibial tubercle on patellofemoral mechanics and kinematics
American Journal of Sports Medicine, 2006Co-Authors: Arun J Ramappa, David R. Wilson, Maria Apreleva, Fraser R Harrold, Peter G Fitzgibbons, Thomas J GillAbstract:BackgroundMedialization and anteromedialization of the tibial tubercle are used to correct patellar subluxation in adults.PurposeTo compare the effects of the 2 osteotomies on patellofemoral joint contact pressures and kinematics.Study DesignControlled laboratory study.MethodsTibial tubercle osteotomies were performed on 10 cadaveric human knees. The knees were tested between 0° and 90° of flexion while dynamic patellofemoral joint contact pressure and kinematic data were simultaneously obtained. Four conditions were tested: normal knee alignment, simulated increased Q Angle, postmedialization of the tibial tubercle, and postanteromedialization of the tubercle.ResultsAn increased Q Angle laterally translated the patella, shifted force to the lateral facet, and increased patella contact pressures. Both medialization and anteromedialization partially corrected the abnormal contact pressures. Medialization partially corrected the shift of force to the lateral facet induced by an increased Q Angle, whereas th...
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evaluation of a computational model used to predict the patellofemoral contact pressure distribution
Journal of Biomechanics, 2004Co-Authors: John Joseph Elias, Robert Adamson, David R. Wilson, Andrew J. CosgareaAbstract:Abstract One possible cause of patellofemoral pain syndrome is excessive lateral force acting on the patella. Although several treatment methods focus on decreasing the lateral force acting on the patella, the relationship between the lateral force and the patellofemoral contact pressure distribution is unclear. A computational model has been developed to determine how loading variations alter the patellofemoral force and pressure distributions for individual knees. The model allows variation in the Quadriceps and patella tendon forces, and calculates the predicted contact pressure distribution using the discrete element analysis techniQue. To characterize the accuracy of the model, four cadaver knees were flexed on a knee simulator with three initial Q-Angles, while recording the force and pressure distributions with a pressure sensor. A model of each knee was created from CT data. Using the external force applied to the knee, the geometry of the knee, and the Quadriceps origin as input, the pressure distribution was calculated during flexion. Similar trends were noted for the computational and experimental results. The percentage of the total force applied to the lateral cartilage increased with the Q-Angle. The maximum contact pressure increased during flexion. The maximum lateral contact pressure increased with the Q-Angle for three knees. For the other knee, increasing the Q-Angle decreased the maximum lateral pressure. The maximum medial contact pressure decreased as the Q-Angle increased. By characterizing the influence of patellofemoral loading on the force and pressure distributions, the computational model could be used to evaluate treatment methods prescribed for patellofemoral pain.
Hyunju Lee - One of the best experts on this subject based on the ideXlab platform.
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effects of medial lateral wedge and difference of Quadriceps Angle on vastus medialis obliQue vastus lateralis muscle activity ratios
Physical Therapy Korea, 2005Co-Authors: Won Gyu Yoo, Hyunju LeeAbstract:Patellofemoral pain syndrome (PFPS) is often attributed to malalignment and maltracking of patella within the patellofemoral joint. Most exercise for PFPS has focused on selectively strengthening the vastus medialis obliQue muscle (VMO). This study was designed to identify the effect of medial, lateral wedge and difference of Quadriceps Angle (Q-Angle) on vastus medialis obliQue/vastus lateralis muscle (VL) activity ratios. The subjects were twenty young adult males who had not experienced any knee injury. They were asked to perform isometric contraction exercises in three postures using medial and lateral wedge. The EMG activity of the VL and VMO were recorded in three postures by surface electrodes and normalized by %MVC values derived from seated, isometric knee extensions. The normalized EMG activity levels (%MVC) of the VL and VMO for the three postures of the lower extremities were compared using 2-way repeated measures ANOVA with 1 between-subject factor (group), and 1 within-subject factor (wedge). Results of repeated measures of ANOVA's revealed that the medial wedge isometric contraction exercise produced significantly greater EMG activity of VMO/VL ratios in Group I (Q-Angle or less) (p or more) (p>.05). These results have important implications for selective VMO muscle strengthening exercises in PFPS patients.
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effects of a combined posture of the lower extremity on activity of the vastus medialis obliQue muscle and vastus lateralis muscle during static sQuat exercise
Physical Therapy Korea, 2004Co-Authors: Won Gyu Yoo, Hyunju LeeAbstract:Most exercise for Patellofemoral pain syndrome (PFPS) has focused on selectively strengthening the vastus medialis obliQue muscle (VMO). Although open chain knee extension exercises are effective for increasing overall Quadriceps strength, they are not always indicated for PFPS rehabilitation. This study was designed to identify the effect of combined posture of lower extremity on Electromyographic (EMG) activity of the vastus lateralis muscle (VL) and VMO during static sQuat exercises. The subjects were twenty young adult males who had not experienced any knee injury and their Q-Angle was within a normal range. They were asked to perform static sQuat exercises in five various postures using their lower extremities. The EMG activity of the VL and VMO were recorded in five exercises by surface electrodes and normalized by %MVC values derived from seated, isometric knee extensions. The normalized EMG activity levels (%MVC) of the VL and VMO for the five postures of the lower extremities were compared using one way ANOVA with repeated measures. Results of repeated measures of ANOVA's revealed that exercise 3 and exercise 5 produced significantly greater EMG activity of VMO/VL ratios than exercise 1 (p
