Comparisons of Vastus Lateralis Architecture and Biomechanical Characteristics during Drop Landing in Young Football Players

PURPOSE: The purpose of this study was to compare the vastus lateralis (VL) architecture and exercise biomechanics indices during drop landing in young football players.METHODS: Fifteen young football players were divided into a long vastus lateralis muscle fascicle length group (LFG, n=8) and short vastus lateralis muscle fascicle length group (SFG, n=7). All of the participants performed drop landing onto the ground reaction force plate from a platform 30 cm high. The muscle activities of the VL, tibialis anterior (TA), and gastrocnemius (GCM), angular velocity, and ground reaction force in the ankle, knee, and hip joints were measured during drop landing.RESULTS: The VL muscle activity (<i>p</i>=.032), ankle ground contact angle (<i>p</i>=.027), ankle maximum flexion angle (<i>p</i>=.014), knee maximum flexion angle (<i>p</i>=.007), and ground reaction force per body weight (<i>p</i>=.032) were significantly higher in the LFG than in the SFG. Muscle activity of the TA (<i>p</i>=.017), ankle (<i>p</i>=.033), and hip (<i>p</i>=.045) time to stability and the ground reaction force time to stability (<i>p</i>=.043) were significantly lower in the LFG than in the SFG. Muscle activity of the GCM (<i>p</i>=.053) and knee time to stability (<i>p</i>=.057) tended to be lower in the LFG than in the SFG.CONCLUSIONS: These results confirmed that muscle activity, angular velocity, and ground reaction force variables during drop landing are affected by the VL muscle fascicle length in young football players.

Single-Leg Squat Performance and Its Relationship to Extensor Mechanism Strength After Anterior Cruciate Ligament Reconstruction

Background: Performance in strength and functional testing is important when considering return to sport after anterior cruciate ligament (ACL) reconstruction. Both knee extensor strength and the single-leg squat (SLS) have been used in this context. Purpose: To evaluate the relationship between knee extensor strength and SLS performance after primary ACL reconstruction. Study Design: Cohort study (Diagnosis); Level of evidence, 3. Methods: A prospective cohort of 100 patients was assessed 6 and 12 months after primary ACL reconstruction with a hamstring tendon autograft. Knee extensor peak torque was measured. Three sequential SLSs were performed, and the maximum flexion angle identified from frame-by-frame video analysis was used as the measure of squat performance. A limb symmetry index (LSI) was calculated and satisfactory performance defined as ≥90%. Results: Extensor mechanism strength deficits were seen in 75% of patients at 6 months and 57% at 12 months postoperatively. Mean extensor mechanism strength showed a large improvement between 6 and 12 months (123.6 vs 147.8 N·m, respectively; P < .001; Cohen d = 1.10), and while there was also a statistically significant improvement in the mean maximum flexion angle, the change was small (66.1° vs 68.1°, respectively; P = .011; Cohen d = 0.26). There was a weak positive correlation between knee extensor strength and the SLS maximum flexion angle at 6 months ( r = 0.342; P < .001) and 12 months ( r = 0.245; P = .014). An SLS LSI <90% was 80% specific and 35% sensitive for extensor mechanism weakness at 6 months and 79% specific and 18% sensitive at 12 months. Conclusion: Extensor mechanism strength deficits are common after ACL reconstruction but reduce between 6 and 12 months. The SLS maximum flexion angle has a weak linear relationship to knee extensor strength. SLS performance has high specificity but low sensitivity in identifying extensor mechanism strength deficits. The SLS maximum flexion angle is therefore a suboptimal surrogate test to identify extensor mechanism strength deficits as diagnosed by isokinetic dynamometric testing. However, unsatisfactory SLS performance indicates a very high chance of underlying extensor mechanism weakness.

Periarticular injection of tranexamic acid promotes early recovery of the range of knee motion after total knee arthroplasty

Purpose: Tranexamic acid (TXA) is a commonly used compound that reduces postoperative blood loss. Periarticular injection of TXA is a recently reported procedure with some advantages such as cost-effectiveness and the ease of performance over an intravenous or topical administration. However, its association with functional recovery remains unclear. This study aimed to examine the effect of periarticular injection of TXA on early postoperative recovery of knee functionality after total knee arthroplasty (TKA). Methods: Eighty-four patients who underwent primary unilateral TKA from February 2013 to August 2016 were classified into two groups based on whether they received TXA injection (44 cases each in the TXA and control groups). Patients in the TXA group received periarticular injection of TXA (1000 mg) just prior to incision closure. Ten-meter walk test (s), pain visual analog scale, knee extension muscle force (N), range of motion (ROM) (maximum flexion angle, maximum extension angle, and motion arc), and blood loss (mL) were assessed. Results: The maximum flexion angle and maximal extension angle on postoperative day (POD) 4, POD7, POD10, and POD14 in the TXA group were significantly larger than those in the control group. The postoperative drained blood in the TXA group was significantly less than that of the control group (543.9 ± 464.3 mL and 814.9 ± 481.4 mL, respectively, p < 0.05). No significant difference was observed in the other parameters at any time point. Conclusion: Periarticular injection of TXA significantly promotes early recovery of knee ROM after TKA. Level of Evidence: Level IV, therapeutic case series.

The level of intelligence relationship kinetic response in obese children, ages (7-9 years)

The skill of beating overwhelming is the most important of those attacking skills that must be accessed by a very advanced stage of the stages of learning, manifested us the importance of research in the study and assess the level of motion mechanism with national team players Iraqi volleyball using science biomchanic as a way to evaluate so that we can determine the level of similarity locomotor performance of members of the sample and thus giving the perception of what the nature of motor performance , as is the research in this area of service for each players and coaches alike. As the research aims to assess the level of performance of the mechanism beating overwhelming higher skill through some of the variables biomchanic with national team players Iraqi volleyball . The researchers ended up to a total of the most important conclusions : 1. achieved the members of the research sample similar values for each of the variables of the maximum flexion angle of the knee joint of the man left during the jump, as well as in variable distance jump, which means that there are stable in the quality of the performance stage Althmadah beaten overwhelming higher for per player , and the mechanism of learning . 2. achieved the members of the research sample similar values for each of the variable maximum flexion angle of the right leg for a moment of payment as well as in variable maximum flexion angle of the hip moment of payment , which means that there are stable in the quality of the performance stage Alnhi beaten overwhelming higher for per player , and the mechanism of learning

Prediction of thigh-calf contact parameters from anthropometric regression

High knee flexion postures are common in industry and cultural practices, but the mechanical effect of intersegmental force, particularly thigh-calf contact force, on knee joint compressive force is poorly understood. Although some studies have measured thigh-calf contact parameters occurring in a number of high flexion postures, joint contact modeling would benefit from efforts to predict thigh-calf contact force for use in computational models. Therefore, this study assessed the strength of correlations and linear multiple regression models on the following five high flexion thigh-calf contact parameters in a young, healthy population: the onset angle of thigh-calf contact, maximum flexion angle, total thigh-calf contact force, center of force, and contact area at maximum flexion. Regressions used anthropometric values (and in some cases, maximum flexion angle). Overall, maximum flexion angle and center of force location had the most significant correlates and strong linear fits with regressive models. Thigh-calf contact onset, total force magnitude, and contact area had only moderate to weak relationships. An exploratory attempt at regression using grouped movements into gross patterns (e.g. two types of squatting were grouped into a general squatting category) using maximum flexion angle and center of force location as dependent variables resulted in similar model fitting. These findings suggest that a causal relationship between select anthropometrics and lower limb range of motion may exist, but further exploration is necessary to determine clinically reliable predictive models.

Necessary Factors to Achieve Deep Flexion for Asian Populations after Oxford Unicompartmental Knee Arthroplasty

There have been many reports on the clinical outcomes of Oxford unicompartmental knee arthroplasty (UKA); however, none have investigated the influence of flexion angle after UKA on clinical outcomes. The objective of this study was to clarify the relationship between outcomes and the postoperative maximum flexion angle and reveal the necessary factors for maximum flexion angle ≥ 140 degrees which is considered necessary for Asian populations. We categorized 212 UKA patients into the following three groups based on the postoperative maximum flexion angle: group 1 had flexion angle ≥ 140 degrees in 80 patients (38%), group 2 had 130 degrees ≤ flexion angle < 140 degrees in 80 patients (38%), and group 3 had flexion angle < 130 degrees in 52 patients (24%). Furthermore, we compared the postoperative clinical outcomes between the three groups and conducted multivariable regression analyses to assess parameters affecting the flexion angle. Postoperative Knee Society function scores for group 1 was significantly higher than for group 3. Group 1 had higher mean knee injury and osteoarthritis outcome scores (KOOS) in all subscales and significantly higher KOOS scores in the sports and quality of life subscales compared with group 2 and in all subscales compared with group 3. Multivariable logistic regression showed that preoperative flexion angle and tibial component posterior slope were associated with maximum flexion angle ≥ 140 degrees. Maximum flexion angle ≥ 140 degrees after Oxford UKA improved the clinical results, particularly for patient-reported outcomes. Furthermore, the tibial posterior slope was an important factor in achieving maximum flexion angle ≥ 140 degrees in UKA patients.

Relationship Between Bilateral Differences in Single-Leg Jumps and Asymmetry in Isokinetic Knee Strength

The aims of the study were to investigate the differences in kinematics and kinetics between the dominant and nondominant leg during single-leg jumps without arm swing, and to determine the relationship between bilateral asymmetry in isokinetic knee strength and the single-leg jump. Isokinetic knee strength and single-leg jump kinematics and kinetics were measured in 11 male participants. The bilateral asymmetry index was calculated for each parameter. For isokinetic knee strength, there were no significant differences between the dominant and nondominant legs. Significant correlations were observed for the bilateral asymmetry index for isokinetic knee strength at 180 degrees per second and the bilateral asymmetry indexes for maximum flexion angle and the mean knee joint torque during the single-leg jumps. In conclusion, the findings of the current study suggest an association between knee strength imbalances and the joint angle, as well as the torque produced in single-leg jumps, although no relationship between knee strength and jump height was observed.

Tendon adhesion measured by a video-assisted gliding test in a chicken model

We developed a video-assisted gliding test to evaluate the gliding force and the flexion angle with unrestricted joint motion. Tendon adhesion was induced in a chicken model of flexor digitorum profundus (FDP) injury at the annular pulley region of the long toe. The chicken feet were harvested immediately after injury, and 2 weeks and 6 weeks after injury. During the gliding test, the injured FDP was pulled for 15 mm then returned to its initial position. The test was recorded using a video camera and registered to the gliding test mechanical data. The maximum flexion angle and gliding resistance were calculated. The maximum flexion angle was significantly decreased from 78 (SD 10) in controls to 42 (SD 22) in tendons with injury, while gliding resistance was significantly increased in week 2 (0.06, SD 0.05) and week 6 (0.07, SD 0.01) after injury.