THE CRITICAL BEHAVIOR OF THE M. BICEPS FEMORIS FOR THE RISK OF INJURY — A SIMULATION STUDY

2020 ◽  
Vol 20 (01) ◽  
pp. 1950069
Author(s):  
THOMAS ERTELT ◽  
THOMAS GRONWALD
Keyword(s):  
Knee Joint ◽  
Critical Behavior ◽  
Muscle Function ◽  
Injury Risk ◽  
Decisive Role ◽  
Biceps Femoris ◽  
Knee Extension ◽  
Muscle Insertion ◽  
Hamstring Muscles ◽  
And Function

The behavior of the M. biceps femoris with regard to its enormous vulnerability to injuries in sport remains unclear. Despite prevention programs, the rate of injuries of the hamstring muscles has risen by more than 4% in recent years. To get more insights into its function, the aim of this study was to examine the effect of different muscle insertion characteristics and activation levels using a simulation. We created a multi-segmented muscle model for evaluating the critical behavior of M. biceps femoris during a one-legged stopping maneuver. We analyzed muscle function, movement of the knee angle after initial ground contact, the simulated muscle force and the stop torques in the knee joint. The insertion geometry has an elementary effect on knee joint function and contributes to knee extension. The muscle activity plays a decisive role in elementary muscle function regarding the knee joint and in this regard the internal load of the M. biceps femoris increased without showing any visible effects on the kinematics. The anthropometry and function of this muscle needs to be taken into account to assess its effects on injury risk.

scholarly journals Last Resort Salvage of Failed Below Knee Amputations

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0046
Author(s):  
Michael Strauss
Keyword(s):  
Knee Joint ◽  
Knee Extension ◽  
Knee Joints ◽  
Knee Amputation ◽  
Pin Fixation ◽  
Management Protocol ◽  
Innovative Management ◽  
Muscle Fascia ◽  
End Stage ◽  
And Function

Category: Other Introduction/Purpose: The consequences of failed transtibial amputations especially if the remaining tibia is less than 5 cm is revision to an above knee amputation (AKA). This has important ramifications regarding mobility, energy requirements for ambulation and function. An innovative management protocol has been employed to maximize the likelihood of healing and maintaining a functional knee joint. Methods: Five severely vasculopathic patients with failed short transtibial (TT) amputations and greater than 60 degree knee flexion contractures were followed progressively using the protocol of resecting the remaining fibula, releasing the hamstring insertions, debridement of bursa & cicatrix, osteotomy & beveling of the distal end of the tibia, creative flap closures, and maintenance of knee extension with pins or external fixation across the knee joint. The patient’s courses were followed prospectively. All patients were referred for more proximal amputations, but wanted everything possible be done to salvage their knee joints and avoid AKAs. Four of the five patients were diabetic; one was a smoker with osteomyelitis at the end of the tibia. Results: Salvage of the knee joint occurred in 4 of 5 patients (80%) even though the remaining tibia lengths were 5 cm or less. Threaded 3/16th inch Steinmann pins placed cross-wise through the knee joints were used in 4 patients and an external fixator in a 5th patient. The pins remained for 3 to 6 weeks. Four of the 5 patients achieved healing with 2 of the 4 having initial minor wound dehiscences. The failed case occurred in a diabetic patient with renal failure and only collateral circulation below the groin. There was insufficient viable muscle/fascia in this patient to cover the tibia. The 4 patients who avoided an AKA were able to be fitted with TT prostheses and use them in a functional capacity. Conclusion: The use of temporary pin fixation across the knee joint and removal of the remaining fibula to salvage “end stage” failed TT amputations served the purposes of maintaining knee extension during the healing period, allowing closure & healing of threatened and/or dehisced flaps and maintaining knee function. Motivated, compliant patients with failed, otherwise considered non salvageable TT amputations should be considered for using our protocol in deference to proceeding to an AKA.

A New Concept For Isokinetic Hamstring: Quadriceps Muscle Strength Ratio

1998 ◽  
Vol 26 (2) ◽  
pp. 231-237 ◽  
Author(s):  
Per Aagaard ◽  
Erik B. Simonsen ◽  
S. Peter Magnusson ◽  
Benny Larsson ◽  
Poul Dyhre-Poulsen
Keyword(s):  
Muscle Strength ◽  
Angular Velocity ◽  
Knee Joint ◽  
Knee Extensor ◽  
Quadriceps Muscle ◽  
Knee Extension ◽  
Quadriceps Strength ◽  
Strength Ratio ◽  
Joint Stability ◽  
Hamstring Muscles

Conventionally, the hamstring:quadriceps strength ratio is calculated by dividing the maximal knee flexor (hamstring) moment by the maximal knee extensor (quadriceps) moment measured at identical angular velocity and contraction mode. The agonist-antagonist strength relationship for knee extension and flexion may, however, be better described by the more functional ratios of eccentric hamstring to concentric quadriceps moments (extension), and concentric hamstring to eccentric quadriceps moments (flexion). We compared functional and conventional isokinetic hamstring: quadriceps strength ratios and examined their relation to knee joint angle and joint angular velocity. Peak and angle-specific (50°, 40°, and 30° of knee flexion) moments were determined during maximal concentric and eccentric muscle contractions (10° to 90° of motion; 30 and 240 deg/sec). Across movement speeds and contraction modes the functional ratios for different moments varied between 0.3 and 1.0 (peak and 50°), 0.4 and 1.1 (40°), and 0.4 and 1.4 (30°). In contrast, conventional hamstring:quadriceps ratios were 0.5 to 0.6 based on peak and 50° moments, 0.6 to 0.7 based on 40° moment, and 0.6 to 0.8 based on 30° moment. The functional hamstring:quadriceps ratio for fast knee extension yielded a 1:1 relationship, which increased with extended knee joint position, indicating a significant capacity of the hamstring muscles to provide dynamic knee joint stability in these conditions. The evaluation of knee joint function by use of isokinetic dynamometry should comprise data on functional and conventional hamstring:quadriceps ratios as well as data on absolute muscle strength.

scholarly journals A prototype for dynamic knee extension: construction, force characterization and electromiographic responses

2020 ◽  
Vol 14 (3) ◽  
pp. 97-109
Author(s):  
Carlos Augusto Kalva-Filho ◽  
Ricardo Augusto Barbieri ◽  
Vitor Luiz De Andrade ◽  
Ronaldo Bucken Gobbi ◽  
Gabriel Luches Pereira ◽  
...  
Keyword(s):  
Knee Joint ◽  
Motor Behavior ◽  
Vastus Lateralis ◽  
Biceps Femoris ◽  
Knee Extension ◽  
Cycle Ergometer ◽  
Initial Position ◽  
Bicycle Frame ◽  
Force Signal

Background: In the dynamic knee extension (DKE), a metal bar is positioned parallel to bicycle frame, replacing the pedal of a cycle ergometer, which allow consecutives extensions instead of pedaling movement. Considering the fixed ratchet of cycle ergometer, the knee joint returns to its initial position passively, isolating the quadriceps group during the exercise. Thus, DKE can be used to investigate the role of the anterior thigh muscles for the locomotion or balance, for example. However, the DKE ergometer is not commercially available. Aim: to describe the construction of a prototype ergometer for DKE and characterize the force signal and electromyography responses. Methods: Six participants underwent a progressive effort to exhaustion. The electromyography signal of Vastus Lateralis and Biceps Femoris were monitored. The last 10 extensions of each stage were used for analyzes. Results: the force signal has three phases: I: knee extension moment; II: crank draws the metal rod back; III: rapid compression of the load cell by the leg. In addition, Vastus Lateralis activation was higher than Biceps Femoris in all stages (p<0.02). Interpretation: These results demonstrated that is possible to construct an ergometer for DKE, which increase the possibilities of research in motor behavior.

Reciprocal Coactivation Patterns of the Lateral and Medial Quadriceps and Hamstrings during Low- and Moderate-Speed Isokinetic Movement

1998 ◽  
Vol 7 (3) ◽  
pp. 182-196 ◽  
Author(s):  
Ronald V. Croce ◽  
John P. Miller ◽  
Robert Confessore ◽  
James C. Vailas
Keyword(s):  
Knee Joint ◽  
Female Athletes ◽  
Vastus Lateralis ◽  
Biceps Femoris ◽  
Median Frequency ◽  
Vastus Medialis ◽  
Mean Square ◽  
Joint Movement ◽  
Surface Electrodes ◽  
Emg Patterns

The purpose of this study was to examine coactivation patterns of the lateral and medial quadriceps and the lateral and medial hamstrings during low- and moderate-speed isokinetic movements. Twelve female athletes performed isokinetic knee assessments at 60 and 180°/s. Root mean square electromyographic (rmsEMG) activity and the median frequency of the EMG (mfEMG) were determined by placing bipolar surface electrodes on the vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), and medial hamstrings (MH). Results of rmsEMG indicated that the VM showed almost twice the coactivation of the VL (p< .05), and that the BF showed almost four times the coactivation of the MH (p <.05). Finally, differences were noted in the mfEMG (p< .05), with the VM displaying different recruitment patterns at 180°/s as an agonist compared to that as an antagonist. Results indicated that when acting as antagonists, the VM and BE display the greatest EMG patterns during isokinetic knee joint movement.

HISTORIAN ON SOCIAL NETWORKS: SOME METHODOLOGICAL CONSIDERATIONS

2020 ◽  
pp. 223-227
Author(s):  
Vasily Syrov
Keyword(s):  
Social Networks ◽  
Decisive Role ◽  
Professional Community ◽  
Historical Knowledge ◽  
Main Attention ◽  
Web Technologies ◽  
Research Findings ◽  
Methodological Considerations ◽  
And Function

The article discusses some of the research findings related to the topic of the place and function of histori-ans on social networks. The main attention is paid to identifying the role of web technologies in the con-ventional practices of creating historical knowledge creation of historical knowledge. It is emphasized that the thesis about blurring the boundaries between the professional community and users in general does not mean rejection of the recognition of the decisive role of the professional community in the production of knowledge. The ways and methods of historians' actions in social networks and their advantages over traditional methods of knowledge production are revealed.

Vascularized Materials: Grids of Channels and Trees Matched Canopy to Canopy

2006 ◽  
Author(s):  
Sunwoo Kim ◽  
Kuan-Min Wang ◽  
Sylvie Lorente ◽  
Adrian Bejan
Keyword(s):  
Fluid Flows ◽  
Decisive Role ◽  
Network Configuration ◽  
Fundamental Study ◽  
Pressure Drops ◽  
Stream Flows ◽  
Fluid Delivery ◽  
Optimal Flow ◽  
Global Performance ◽  
And Function

This is a fundamental study of how to discover the optimal flow architecture to vascularize a volume so that fluid flow and function (e.g. cooling, sensing, maintenance, repair, healing) reaches every point of the material. The presentation is made by discussing flow architectures that deliver healing fluid to all the crack sites that may occur randomly through the material. Two concepts are explored. In the first, a grid of interconnected channels is built into the material, and is filled with pressurized healing fluid. When a crack forms, the pressure drops at the crack site and fluid flows from the grid into the crack. The objective is to discover the network configuration that is capable of delivering fluid to all the cracks the fastest. It is shown that the optimization of the ratio of channel diameters cuts in half the time of fluid delivery to the crack. In the second concept, one stream flows steadily through the material and bathes it volumetrically. The stream enters through one port, and distributes itself as a river delta through the volume. Later the stream reconstitutes itself as a river basin before exiting the volume through one point. This second concept is equivalent to matching two trees canopy to canopy. It is shown that the choice of tree-tree configuration has a decisive role on the global performance of the vascularized composite.

scholarly journals ROLE OF HAMSTRING MUSCLES IN KNEE JOINT STABILITY PROVIDING AND INJURY PREVENTION

2016 ◽  
Vol 3 ◽  
pp. 522
Author(s):  
Inese Pontaga
Keyword(s):  
Stance Phase ◽  
Knee Extension ◽  
Swing Phase ◽  
Joint Stability ◽  
Distance Runners ◽  
Leg Extension ◽  
Hamstring Muscles ◽  
Extreme Extension ◽  
Torque Values

The aim of our investigation was to determine the ratio of maximal torque values and the torques in the certain positions of range of movements (ROM) between hamstring (H) and quadriceps femoris (Q) muscles at medium and high velocity of movement in concentric (CC) and eccentric (ECC) action of hamstring muscles. The knee muscles of 15 amateur female short and middle distance runners were tested by the dynamometer system in the isokinetic movements with the angular velocity of 90º/s and 240º/s in CC and at the velocity of 90º/s in ECC H/ CC Q muscles contractions. The torque values produced by the muscles are detected at the different angular positions of the ROM with the step of 10º. The ratios of H/ Q muscles torques are calculated. The H/Q muscles maximal torques ratio is 0.51 ± 0.13 at the velocity of 90º/s in CC and 0.60 ± 0.09 in ECC H/ CC Q muscles contractions, and 0.59 ± 0.09 CC at the velocity of 240º/s. The H/Q maximal torques ratio and this ratio in the knee extreme extension and flexion at the ECC contraction of H is higher due to greater torques produced by the H in comparison with Q muscle. The H must be stronger to decelerate the thigh and lower leg extension in the late swing phase of running and to extend the hip in early stance phase to provide powerful sprint running and prevent the knee and H injury. The H/Q muscles torques ratio in extended knee positions are similar in medium (90º/s) and fast (240º/s) velocity of motions because CC action of H muscles cannot prevent extreme knee extension.

scholarly journals Neuromuscular Control of the Knee during a Resisted Single-Limb Squat Exercise

2005 ◽  
Vol 33 (10) ◽  
pp. 1520-1526 ◽  
Author(s):  
Richard K. Shields ◽  
Sangeetha Madhavan ◽  
Emy Gregg ◽  
Jennifer Leitch ◽  
Ben Petersen ◽  
...  
Keyword(s):  
Body Weight ◽  
Knee Joint ◽  
Knee Flexion ◽  
Neuromuscular Control ◽  
Biceps Femoris ◽  
Medial Gastrocnemius ◽  
Isometric Contractions ◽  
Low Resistance ◽  
Squat Exercise ◽  
Flexion And Extension

Background Closed kinetic chain exercises such as single-limb squats are preferred for knee rehabilitation. A complete understanding of the neuromuscular control of the knee during the single-limb squat is essential to increase the efficiency of rehabilitation programs. Hypothesis Performing a controlled single-limb squat with resistance to knee flexion and extension will increase the coactivation of the hamstring muscle group, thus reducing the quadriceps/hamstrings ratio. Study Design Descriptive laboratory study. Methods A total of 15 healthy human subjects (7 women, 8 men) performed controlled single-limb squats in a custom mechanical device that provided resistance to both flexion and extension. Subjects performed the task at 3 levels of resistance, set as a percentage of body weight. Surface electromyographic recordings from 7 muscles (gluteus medius, rectus femoris, vastus medialis oblique, vastus lateralis, biceps femoris, semitendinosus, and medial gastrocnemius) were collected during the task. Results Biceps femoris activity during knee flexion increased from approximately 12% maximum voluntary isometric contractions during low resistance (0% body weight) to approximately 27% maximum voluntary isometric contractions during high resistance (8% body weight). Although the quadriceps had greater activity than the hamstrings at all levels of resistance, the quadriceps/hamstrings ratio declined significantly with resistance (F2,27 = 29.05; P=. 012) from 3.0 at low resistance to 2.32 at the highest resistance. Conclusions Performing controlled resisted single-limb squats may help to simultaneously strengthen the quadriceps and facilitate coactivation of the hamstrings, thus reducing anterior tibial shear forces. The coactivation may also increase the dynamic control of the knee joint. Clinical Relevance The typical single-limb squat exercise performed in the clinic does not usually control for bidirectional resistance and knee joint excursion. As seen in this study, controlled single-limb squats at increased levels of resistance help to increase the coactivation of the hamstring muscles, which is essential to optimize neuromuscular control of the knee.

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