Increased Knee Flexion Angle Research Articles

Mechanisms underpinning the peak knee flexion moment increase over 2-years following arthroscopic partial meniscectomy

BackgroundKnee osteoarthritis is common in people who have undergone partial meniscectomy, and a higher external knee flexion moment during gait may be a potential contributor. Although the peak external knee flexion moment has been shown to increase from 3months to 2years following partial meniscectomy, mechanisms underpinning the increase in the peak knee flexion moment are unknown. MethodsSixty-six participants with partial meniscectomy completed three-dimensional gait (normal and fast pace) and quadriceps strength assessment at baseline (3months following partial meniscectomy) and again 2years later. Variables included external knee flexion moment, vertical ground reaction force, knee flexion kinematics, and quadriceps peak torque. FindingsFor normal pace walking, the main significant predictors of change in peak knee flexion moment were an increase in peak vertical ground reaction force (R2=0.55), mostly due to an increase in walking speed, and increase in peak knee flexion angle (R2=0.19). For fast pace walking, the main significant predictors of change in peak knee flexion moment were an in increase in peak vertical ground reaction force (R2=0.51) and increase in knee flexion angle at initial contact (R2=0.17). Change in peak vertical force was mostly due to an increase in walking speed. InterpretationFindings suggest that increases in vertical ground reaction force and peak knee flexion angle during stance are predominant contributors to the 2-year change in peak knee flexion moment. Future studies are necessary to refine our understanding of joint loading and its determinants following meniscectomy.

Biomechanical Effects of Neuromuscular Training in Anterior Cruciate Ligament-Reconstructed Subjects

Objectives:Second anterior cruciate ligament (ACL) injuries occur at a 10-20-fold higher rate than primary injury, and result in significantly poorer outcomes. Targeted neuromuscular training (NMT) alters biomechanics and reduces rates of primary ACL injury, but its effects in an ACL-injured population have not been elucidated. The purpose of this study was to determine the effects of NMT on high-risk biomechanics at the hip and knee in ACL-reconstructed (ACLR) subjects. We hypothesized that trained subjects would demonstrate reduced peak hip rotation and knee abduction motion and moments compared to controls.Methods:13 ACLR subjects (7 males and 6 females, 20.15±7.97 years old) were enrolled and evaluated during drop vertical jump (DVJ), single leg drop (SLD), and crossover drop (COD) tasks using 3D motion analysis prior to and after participation in a 12 session NMT program (Pre: 36.0±18.3 weeks post-operative, Post: 46.6±17.4 weeks post-operative). 13 untrained, ACLR controls (9 males and 4 females, 20.77±6.55 years old) were tested 52.4±2.7 weeks post-operative. Trained subjects participated in a 12 session training program, modified to be safe for patients in the late recovery phase after ACL-injury. The protocol centered around seven separate progressions, each consisting of four phases of increasing difficulty. Each phase consists of a cognitive session, associative session, and autonomous session.1 Discrete variables for hip and knee kinematics and kinetics, and vertical ground reaction force were compared within and between groups. Limb-by-session repeated measures analysis of variance (ANOVA) was used to assess within-subject effects of training. A separate limb-by-group ANOVA was used to compare trained and untrained groups.Results:Frontal plane hip excursion during the COD decreased after training. Trained subjects demonstrated increased knee flexion at initial contact during the DVJ task after training (NMT_Pre: -17.1±6.7 degrees , NMT_Post: -22.5±10.2 degrees; p=0.02). Changes in knee kinematics from pre-to post-NMT are shown in Figure 1. Peak knee flexion within the first 20% of landing increased significantly after NMT (NMT_Pre: -69.2±8.8 degrees, NMT_Post: -74.8±9.2 degrees; p=0.0067) as well as throughout the task (NMT_Pre: -88.2±12.1 degrees, NMT_Post: -95.0±12.5 degrees; p=0.0095). Trained subjects demonstrated significantly greater knee flexion range of motion within the first 20% of the landing phase of DVJ compared to controls (NMT_Post: 52.3±12.8 degrees, CTRL: 45.6±7.7 degrees; p=0.0214). Trained groups demonstrated greater peak knee flexion and flexion ROM compared to controls (p<0.05). Peak hip flexion during the first 20% of DVJ increased from pre- to post-training, but only trended toward differing from controls (p=0.0879).Conclusion:Increased knee flexion angles for both unilateral and bilateral tasks were consistently observed from pre- to post-training. Furthermore, the trained group exhibited significantly greater peak flexion compared to controls during the initial landing phase for most tasks, when ACL injury is most likely to occur. NMT in ACL-reconstructed subjects appeared to primarily affect sagittal plane hip and knee biomechanics.

The Shank-to-Vertical-Angle as a parameter to evaluate tuning of Ankle-Foot Orthoses

The effectiveness of an Ankle-Foot Orthosis footwear combination (AFO-FC) may be partly dependent on the alignment of the ground reaction force with respect to lower limb joint rotation centers, reflected by joint angles and moments. Adjusting (i.e. tuning) the AFO-FC's properties could affect this alignment, which may be guided by monitoring the Shank-to-Vertical-Angle. This study aimed to investigate whether the Shank-to-Vertical-Angle during walking responds to variations in heel height and footplate stiffness, and if this would reflect changes in joint angles and net moments in healthy adults. Ten subjects walked on an instrumented treadmill and performed six trials while walking with bilateral rigid Ankle-Foot Orthoses. The AFO-FC heel height was increased, aiming to impose a Shank-to-Vertical-Angle of 5°, 11° and 20°, and combined with a flexible or stiff footplate. For each trial, the Shank-to-Vertical-Angle, joint flexion–extension angles and net joint moments of the right leg at midstance were averaged over 25 gait cycles. The Shank-to-Vertical-Angle significantly increased with increasing heel height (p<0.001), resulting in an increase in knee flexion angle and internal knee extensor moment (p<0.001). The stiff footplate reduced the effect of heel height on the internal knee extensor moment (p=0.030), while the internal ankle plantar flexion moment increased (p=0.035). Effects of heel height and footplate stiffness on the hip joint were limited. Our results support the potential to use the Shank-to-Vertical-Angle as a parameter to evaluate AFO-FC tuning, as it is responsive to changes in heel height and reflects concomitant changes in the lower limb angles and moments.

In‐vivo three‐dimensional knee kinematics during daily activities in dogs

The canine knee is morphologically similar to the human knee and thus dogs have been used in experimental models to study human knee pathology. To date, there is limited data of normal canine 3D knee kinematics during daily activities. The objective of this study was to characterize 3D in-vivo femorotibial kinematics in normal dogs during commonly performed daily activities. Using single-plane fluoroscopy, six normal dogs were imaged performing walk, trot, sit, and stair ascent activities. CT-generated bone models were used for kinematic measurement using a 3D-to-2D model registration technique. Increasing knee flexion angle was typically associated with increasing tibial internal rotation, abduction and anterior translation during all four activities. The precise relationship between flexion angle and these movements varied both within and between activities. Significant differences in axial rotation and coronal angulation were found at the same flexion angle during different phases of the walk and trot. This was also found with anterior tibial translation during the trot only. Normal canine knees accommodate motion in all planes; precise kinematics within this envelope of motion are activity dependent. This data establishes the characteristics of normal 3D femorotibial joint kinematics in dogs that can be used as a comparison for future studies.

Fatigue Reduces the Ability of Shock Attenuation during Landings of Drop Vertical Jump

PURPOSE: There are some researches focused on lower extremity kinematics during drop vertical jumps. It has been considered and recently attracted attention that fatigue decreases the ability to attenuate shock for lower extremity during landings. Fatigue on lower extremity kinematics is considered to reveal risks regarding non-contact anterior cruciate ligament injury. However, the effect of lower extremity kinematics on shock attenuation during drop vertical jump has not been clarified. The purpose of this study is to reveal characteristic of lower extremity kinematics on shock attenuation during drop vertical jump in fatigue condition. METHODS: Nine healthy college female (age = 21.1±2.5 years old, height = 161.1±3.6 cm, weight = 53.4±8.9 kg) volunteered to participate in this experiment. All of them gave written informed consent before this experiment. They performed drop vertical jumps before and after completing the fatigue protocol. The fatigue protocol was performed by using a bike ergometer. Lower kinematics and kinetics data were obtained from the three-dimensional motion analysis system with eight cameras (Vicon MX, Vicon Motion Systems, Oxford, UK) and three force plates (MSA-6, AMTI, Mass., USA). Maximum knee flexion angle, angular velocity and minimum angular acceleration were analyzed from initial contact to toe off during the first landing of drop vertical jump. Times from initial contact to peak knee flexion angle normalized to 100% of the first landing phase. Paired T test was used to identify differences of lower extremity kinematics between before and after completing fatigue protocol. RESULTS: Maximum knee flexion angle, angular velocity had no differences between before and after completing the fatigue protocol. Minimum knee flexion acceleration decreased significantly (-160.0 vs. -171.8 rad/s2, P<0.05) and times from initial contact to peak knee flexion angle shortened significantly after completing the fatigue protocol (47.4 vs. 45.5 %, P<0.05). CONCLUSIONS: Landings in fatigue condition decelerated by increasing knee flexion angle in a short time. Times from initial contact to peak knee flexion angle shortened, however, peak knee flexion angle were not altered in fatigue condition. Our study indicates that fatigue induced decreased the ability to attenuate shock by shortened times to peak knee flexion angle and decreased knee flexion acceleration during drop vertical jump.

Fatigue Alters Shock Attenuation during Landings of Sidestep Cutting

PURPOSE: Landings in fatigue condition are considered to be one of the factors to cause non-contact anterior cruciate ligament injury. It is known that fatigue alters lower extremity landing strategies and decreases the ability to attenuate shock during landing. However, lower extremity kinematics and shock attenuation during landings of sidestep cutting movement in fatigue condition has not been clarified. The purpose of this study is to reveal characteristic of lower extremity kinematics and shock attenuation during landings of sidestep cutting in fatigue condition. METHODS: Ten healthy female (age = 21.2±2.3 years old, height = 161.5±3.5 cm, weight = 53.9±8.5 kg) volunteered to participate in this experiment. All of them gave written informed consent before this experiment. They performed sidestep cutting movement before and after completing the fatigue protocol. The fatigue protocol was performed by using a bike ergometer. Lower kinematics and kinetics data were obtained from the three-dimensional motion analysis system with eight cameras (Vicon MX, Vicon Motion Systems, Oxford, UK) and three force plates (MSA-6, AMTI, Mass., USA). Maximum knee flexion angle, angular velocity and minimum angular acceleration were analyzed from initial contact to toe off during landings of sidestep cutting movement. Paired T test was used to identify differences of lower extremity kinematics between before and after completing fatigue protocol. RESULTS: Maximum knee flexion angle, angular velocity and times from initial contact to peak knee flexion angle had no differences between before and after completing the fatigue protocol. Minimum knee flexion acceleration increased significantly after completing the fatigue protocol (-146.9 vs. -165.7 rad/s2, P<0.05). CONCLUSIONS: Sidestep cutting movement in fatigue condition decelerated by increasing knee flexion angle in a short time. Maximum knee flexion angle and times from initial contact to peak knee flexion angle during landings of sidestep cutting movement were not altered. Our study indicates that fatigue decreased the ability to attenuate shock by decreasing minimum angular acceleration of knee flexion during landings of sidestep cutting movement.

The Effects of 2 Landing Techniques on Knee Kinematics, Kinetics, and Performance During Stop-Jump and Side-Cutting Tasks

Background: Anterior cruciate ligament injuries (ACL) commonly occur during jump landing and cutting tasks. Attempts to land softly and land with greater knee flexion are associated with decreased ACL loading. However, their effects on performance are unclear. Hypothesis: Attempts to land softly will decrease peak posterior ground-reaction force (PPGRF) and knee extension moment at PPGRF compared with a natural landing during stop-jump and side-cutting tasks. Attempts to land with greater knee flexion at initial ground contact will increase knee flexion at PPGRF compared with a natural landing during both tasks. In addition, both landing techniques will increase stance time and lower extremity mechanical work as well as decrease jump height and movement speed compared with a natural landing during both tasks. Study Design: Controlled laboratory study. Methods: A total of 18 male and 18 female recreational athletes participated in the study. Three-dimensional kinematic and kinetic data were collected during stop-jump and side-cutting tasks under 3 conditions: natural landing, soft landing, and landing with greater knee flexion at initial ground contact. Results: Attempts to land softly decreased PPGRF and knee extension moment at PPGRF compared with a natural landing during stop-jump tasks. Attempts to land softly decreased PPGRF compared with a natural landing during side-cutting tasks. Attempts to land with greater knee flexion at initial ground contact increased knee flexion angle at PPGRF compared with a natural landing during both stop-jump and side-cutting tasks. Attempts to land softly and land with greater knee flexion at initial ground contact increased stance time and lower extremity mechanical work, as well as decreased jump height and movement speed during both stop-jump and side-cutting tasks. Conclusion: Although landing softly and landing with greater knee flexion at initial ground contact may reduce ACL loading during stop-jump and side-cutting tasks, the performance of these tasks decreased, as indicated by increased stance time and mechanical work as well as decreased jump height and movement speed. Clinical Relevance: Training effects tested in laboratory environments with the focus on reducing ACL loading may be reduced in actual competition environments when the focus is on athlete performance. The effects of training programs for ACL injury prevention on lower extremity biomechanics in athletic tasks may need to be evaluated in laboratories as well as in actual competitions.

The effect of AFO stiffness on the knee joint during the heel strike phase of gait in stroke patients (919.12)

Stroke patients suffering from foot drop are often prescribed ankle‐foot orthoses (AFOs) to improve foot clearance during gait. However, excessive restriction of plantarflexion (PF) during the heel strike phase of gait has been shown to cause biomechanical changes at the knee joint. This pilot study aimed to determine how increasing the PF stiffness of an AFO affects knee joint kinematics and kinetics during heel strike in hemiplegic stroke patients with varying levels of active ankle range of motion. We hypothesized that increased PF resistance would cause an increase in anterior tibial rotation at heel strike with resulting increases in knee flexion angle and knee extension moment. To test this hypothesis, 5 stroke patients with foot drop were clinically evaluated, instrumented with reflective markers, and fitted with a spring modified AFO (Orthocare Innovations). A compression spring in the posterior aspect of the AFO was changed to increase the external dorsiflexion torque from 0.3 Nm/deg (Spring 1) to 2.0 Nm/deg (Spring 2). Kinematic and kinetic data were collected during walking on an instrumented treadmill (Bertec) in a motion analysis lab. Five steps with each spring were examined. Two patients exhibited an increase in knee flexion angle and knee extension moment with the stiffer spring. Clinical findings revealed that these 2 patients had minimal active PF while the other 3 patients had full active PF. From these initial results, we cautiously conclude that stroke patients with decreased active PF cannot overcome excessive PF resistance during the heel strike phase of gait, and as a result exhibit compensation strategies at the knee joint. These results will be used to create a more objective method for the prescription of AFOs in hopes to improve the long‐term quality of life for stroke patients.Grant Funding Source: Supported by National Institutes of Health (2R44HD069095‐02)

Effect of axial loading during knee flexion on ACL end-to-end distance in healthy and ACL-deficient knees

The purpose of this study was to determine the effect of physiological axial loading during knee flexion on changes in anterior cruciate ligament (ACL) end-to-end distance for normal and ACL-deficient knees. Biomechanical tests were conducted on ten cadaveric knees using an Instron machine. We gathered positional data of the tibia and femur at low to middle flexion angles (0°, 15°, 30°, 45° and 60°) with/without axial loading. First, no external load was applied to the specimens at each angle, and then, a 1000-N axial load was applied to the knees. The same test protocols were repeated after transection of the ACL. Using computer software (Geomagic Studio 10), we regenerated positional data and calculated the end-to-end distances of the anteromedial, posterolateral and the entire ACL bundle at each angle. Compared with ACL-intact knees without axial loading, knees under axial loading did not show significant increases in end-to-end distance. Under axial loading, we found no significant differences in end-to-end distances between bundles in ACL-intact knees according to the increase in knee flexion angle. After ACL transection, axial loading significantly increased end-to-end distances of all three bundles (P<0.001), and the distances increased significantly with flexion angle (P<0.05 at all angles in all bundles). The changing patterns of the ACL end-to-end distance in ACL-deficient knees were different from those in healthy knees after applying physiological axial loading, and the ACL end-to-end distances in ACL-deficient knees increased remarkably as knee flexion angles increased.

Effect of a Novel Movement Strategy in Decreasing ACL Risk Factors in Female Adolescent Soccer Players

To determine the effect of a novel movement strategy incorporated within a soccer warm-up on biomechanical risk factors for anterior cruciate ligament injury during 3 sport-specific movement tasks. Single-blind, randomized controlled clinical trial. Laboratory setting. Twenty top-tier female teenage soccer players. Subjects were randomized to the Core Position and Control movement strategy (Core-PAC) warm-up or standard warm-up, which took place before their regular soccer practice over a 6-week period. The Core-PAC focuses on getting the centre of mass closer to the plant foot or base of support. Peak knee flexion angle and abduction moments during a side-hop (SH), side-cut, and unanticipated side-cut task after the 6 weeks with (intervention group only) and without a reminder to use the Core-PAC strategy. The Core-PAC group increased peak flexion angles during the SH task [mean difference = 6.2 degrees; 95% confidence interval (CI), 1.9-10.5 degrees; effect size = 1.01; P = 0.034] after the 6-week warm-up program without a reminder. In addition, the Core-PAC group demonstrated increased knee flexion angles for the side-cut (mean difference = 8.5 degrees; 95% CI, 4.8-12.2 degrees; ES = 2.02; P = 0.001) and SH (mean difference = 10.0 degrees; 95% CI, 5.7-14.3 degrees; ES = 1.66; P = 0.001) task after a reminder. No changes in abduction moments were found. The results of this study suggest that the Core-PAC may be one method of modifying high-risk soccer-specific movements and can be implemented within a practical, team-based soccer warm-up. The results should be interpreted with caution because of the small sample size.

Effects of Knee Extension Constraint Training on Knee Flexion Angle and Peak Impact Ground-Reaction Force

Background: Low compliance with training programs is likely to be one of the major reasons for inconsistency of the data regarding the effectiveness of current anterior cruciate ligament (ACL) injury prevention programs. Training methods that reduce training time and cost could favorably influence the effectiveness of ACL injury prevention programs. A newly designed knee extension constraint training device may serve this purpose. Hypothesis: (1) Knee extension constraint training for 4 weeks would significantly increase the knee flexion angle at the time of peak impact posterior ground-reaction force and decrease peak impact ground-reaction forces during landing of a stop-jump task and a side-cutting task, and (2) the training effects would be retained 4 weeks after completion of the training program. Study Design: Controlled laboratory study. Methods: Twenty-four recreational athletes were randomly assigned to group A or B. Participants in group A played sports without wearing a knee extension constraint device for 4 weeks and then played sports while wearing the device for 4 weeks, while participants in group B underwent a reversed protocol. Both groups were tested at the beginning of week 1 and at the ends of weeks 4 and 8 without wearing the device. Knee joint angles were obtained from 3-dimensional videographic data, while ground-reaction forces were measured simultaneously using force plates. Analyses of variance were performed to determine the training effects and the retention of training effects. Results: Participants in group A significantly increased knee flexion angles and decreased ground-reaction forces at the end of week 8 (P ≤ .012). Participants in group B significantly increased knee flexion angles and decreased ground-reaction forces at the ends of weeks 4 and 8 (P ≤ .007). However, participants in group B decreased knee flexion angles and increased ground-reaction forces at the end of week 8 in comparison with the end of week 4 (P ≤ .009). Conclusion: Knee extension constraint training for 4 weeks significantly altered lower extremity movement patterns and transferred these changes in lower extremity movement patterns to stop-jump and side-cutting tasks in which ACL injuries frequently occur. Training effects were retained 4 weeks after the training was completed but were diminished in magnitude. Clinical Relevance: A knee extension constraint device may be a useful training tool in future ACL injury prevention programs to alter movement patterns without extra training time.

Control of postural alignment in patients with Parkinsons disease: analysis through postural software (SAPO)

This study assesses the alignment of posture and postural control in patients with Parkinson’s disease (PD). Fifty individuals, aged 60–80 years, were viewed in the anterior, posterior, right lateral, and left positions by software for postural assessment (SAPO). The individuals were grouped according to the disease stage and the stage of medication (i.e. “on” or “off” levodopa). In the intermediate to advanced stages, there was a significant standard deviation in the horizontal alignment acromions, in the horizontal alignment of the anterior superior iliac spines, and in the angle between the acromia and the two anterior superior iliac spines. The side view of the left and right relationships was statistically significant for all variables. The “on” stage and the “off” stage groups showed no significant deviation. There was no statistically significant correlation between the center of gravity in the frontal and sagittal planes of the dominant hand and the side of symptom onset. In PD, individuals have increased cervical lordosis and thoracic kyphosis; an anteriorized head; reduced lumbar curvature; increased valgus, increased knee flexion angle; a decline in the support base; zero step; reduced postural stability; anteriorized center of gravity; and changes in the base of support.

Effects of Stability by Using Different Types of Taping on Knee Joint during a Jump-stop Task

The purpose of this study was to investigate the effects of stability by using different types of taping on knee joint during a jump-stop task. Eight healthy males (aged=19.5±1.2 year, height=174.3±5.9 cm, weight=65.9±4.2 kg) were participated in this study. All the participants performed a jump-stop task under three knee taping conditions (traditional taping, Kinesio taping and non-taping). A high speed camera (Mega Speed 30 Ks), two AMTI force plates and four Biovision electromyography (EMG) systems were used synchronously to collect kinematic, kinetic and EMG data during the landing phase. The Kwon3D and DASYLab 6.0 software were used for further analyses of the data. The results indicated that smaller maximal anteroposterior force and fewer displacement of anteroposterior center of pressure were observed under the traditional and Kinesio taping conditions than the non-taping condition. A smaller average loading rate was reported with the Kinesio taping compared to the non-taping. Regarding kinematic parameters, an increased knee flexion angle at peak impact was observed under the traditional and Kinesio taping conditions than the non-taping condition. A larger maximum knee flexion angle was reported under the Kinesio taping compared to the non-taping. Furthermore, smaller mean EMG amplitudes were found in the rectus femoris and gastrocnemius muscles under the traditional and Kinesio taping conditions. The study concluded that the traditional and Kinesio taping techniques effectively increases the stability by giving a strong support and limiting the forward displacement of the anterior cruciate ligament at a jump-stop task. The Kinesio taping is also beneficial to increase the range of motion of knee joint.

A Kinetic and Kinematic Analysis of the Effect of Stochastic Resonance Electrical Stimulation and Knee Sleeve During Gait in Osteoarthritis of the Knee

Extended use of knee sleeves in populations at risk for knee osteoarthritis progression has shown functional and quality of life benefits; however, additional comprehensive kinematic and kinetic analyses are needed to determine possible physical mechanisms of these benefits which may be due to the sleeve's ability to enhance knee proprioception. A novel means of extending these enhancements may be through stochastic resonance stimulation. Our goal was to determine whether the use of a knee sleeve alone or combined with stochastic resonance electrical stimulation improves knee mechanics in knee osteoarthritis. Gait kinetics and kinematics were assessed in subjects with medial knee osteoarthritis when presented with four conditions: control1, no electrical stimulation/sleeve, 75% threshold stimulation/sleeve, and control2. An increase in knee flexion angle throughout stance and a decrease in flexion moment occurring immediately after initial contact were seen in the stimulation/sleeve and sleeve alone conditions; however, these treatment conditions did not affect the knee adduction angle and internal knee abduction moment during weight acceptance. No differences were found between the sleeve alone and the stochastic resonance with sleeve conditions. A knee sleeve can improve sagittal-plane knee kinematics and kinetics, although adding the current configuration of stochastic resonance did not enhance these effects.

The effect of patellofemoral bracing on walking in individuals with patellofemoral pain syndrome

Although knee braces are used by individuals with patellofemoral pain syndrome, the effect of patellofemoral bracing on knee flexion during walking has not been elucidated. The purpose of this study was to evaluate the effect of patellofemoral bracing on sagittal plane knee joint kinematics and temporal spatial parameters during walking in individuals with patellofemoral pain syndrome. Quasi-experimental. Ten subjects with a diagnosis of patellofemoral pain syndrome were fitted with a knee brace incorporating an infrapatellar strap. Testing was performed at baseline and after 6 weeks of use. Gait analysis and a visual analog scale were used to assess outcomes in this study. A 59.6% decrease in pain was reported by using bracing. Bracing significantly improved speed of walking (p ≤ 0.001) and step length (p ≤ 0.001). The mean cadence was also increased following 6 weeks of patellofemoral brace use, but this was not significant (p = 0.077). Knee flexion angles improved during initial contact, loading response, and mid-swing (p ≤ 0.001) after 6 weeks of patellofemoral brace use. Knee orthoses resulted in decreased pain, improved temporal spatial parameters (speed of walking and step length), and increased knee flexion angles during ambulation in patients with patellofemoral pain syndrome.

The Effect of a Knee-ankle Restraint on ACL Injury Risk Reduction during Jump-landing

Anterior cruciate ligament (ACL) is the most commonly injured ligament. It has a great impact on athletes causing long absence from play and is linked with increased risks of osteoarthritis. Today, literature suggests that the knee braces may not completely reduce ACL injury mechanism risks. Ankle braces, on the other hand, have shown promising results in some of these aspects. Thus, the purpose of this research is to study the effectiveness of a knee- ankle brace restraint in reducing ACL injury risks by increasing knee flexion and reducing knee valgus angles. Eighteen healthy Asian male subjects performed a drop vertical jump maneuver from a 31cm platform. A motion analysis capture was carried out to measure the knee flexion and knee valgus angles. Results show that the effect of a knee-ankle brace restraint was insignificant in increasing knee flexion and in reducing knee valgus angles at initial contact and at peak vertical ground reaction force (VGRF). While the ankle brace showed some trends of increasing knee flexion angles at initial contact, the effect was insignificant. Similarly, the ankle brace did not show significant effects on knee flexion angles at peak VGRF and on knee valgus angles at both instances. The knee brace had little effect on knee flexion angles but showed significant effects on valgus angle increase. In conclusion, a knee-ankle brace restraint was not found to have an effect on reducing ACL injury risks during jump-landing. Ankle brace use did not adversely increase ACL injury risks but has shown weak effects in reducing the risks. The knee brace used in this study was not found to be suitable for reducing valgus angles.

The Effect of Foot Progression Angle on Knee Joint Compression Force During Walking

It is unclear how rotations of the lower limb affect the knee joint compression forces during walking. Increases in the frontal plane knee moment have been reported when walking with internally rotated feet and a decrease when walking with externally rotated feet. The aim of this study was to investigate the knee joint compressive forces during walking with internal, external and normal foot rotation and to determine if the frontal plane knee joint moment is an adequate surrogate for the compression forces in the medial and lateral knee joint compartments under such gait modifications. Ten healthy males walked at a fixed speed of 4.5 km/h under three conditions: Normal walking, internally rotated and externally rotated. All gait trials were recorded by six infrared cameras. Net joint moments were calculated by 3D inverse dynamics. The results revealed that the medial knee joint compartment compression force increased during external foot rotation and the lateral knee joint compartment compression force increased during internal foot rotation. The increases in joint loads may be a result of increased knee flexion angles. Further, these data suggest that the frontal plane knee joint moment is not a valid surrogate measure for knee joint compression forces but rather indicates the medial- to-lateral load distribution.

Evaluation of gait and slip parameters for adults with intellectual disability

Adults with intellectual disability (ID) experience more falls than their non-disabled peers. A gait analysis was conducted to quantify normal walking, and an additional slip trial was performed to measure slip response characteristics for adults with ID as well as a group of age- and gender-matched controls. Variables relating to gait pattern, slip propensity, and slip severity were assessed to compare the differences between groups. The ID group was found to have significantly slower walking speed, shorter step lengths, and increased knee flexion angles at heel contact. These gait characteristics are known to reduce the likelihood of slip initiation in adults without ID. Despite a more cautious gait pattern, however, the ID group exhibited greater slip distances indicating greater slip severity. This study suggests that falls in this population may be due to deficient slip detection or insufficient recovery response.

The Effect of Short-Term Resistance Training on Hip and Knee Kinematics During Vertical Drop Jumps

The purpose of this study was to determine the effect of a weight-bearing free weight resistance training program alone on knee flexion, hip flexion, and knee valgus during unilateral and bilateral drop jump tasks. Twenty-nine young adult females with previous athletic experience were randomly divided into a control (n = 16) and a resistance training (n = 13) groups. The resistance training group completed 8 weeks of lower extremity, weight-bearing exercises using free weights, whereas the control group did not train. A pre- and posttest was conducted to measure knee valgus, knee flexion, and hip flexion during unilateral (30 cm) and bilateral (60 cm) vertical drop jumps for maximum height. Joint angles were determined using 3-dimensional electromagnetic tracking sensors (MotionMonitor; Innovative Sports Training, Inc., Chicago, IL, USA). Initial training intensity for the bilateral squat was 50% of the subject's 1 repetition maximum (RM), which increased 5% each week to 85% during the final week. Sets and repetitions ranged from 2 to 4 and from 4 to 12, respectively. The training loads for all other exercises (lunge, step-up, unilateral squat, and Romanian deadlift) increased from 15RM to 6RM from the initial to the final week. A repeated measures analysis of variance was used to determine differences in the hip and knee joint angles. No significant differences for knee valgus and hip flexion measures were found between the groups after training; however, knee flexion angle significantly increased in the training group from the pretest (77.2 ± 4.1°) to posttest (83.2 ± 3.7°) during the bilateral drop jump. No significant changes occurred during the unilateral drop jump. Bilateral measures for knee flexion, hip flexion, and knee valgus were significantly (p < 0.05) greater than the unilateral measures during the drop jump task, which indicate an increased risk for anterior cruciate ligament (ACL) injury during unilateral drop jumps. The data support that the strength and conditioning specialist can implement resistance training alone during a short-term training period to reduce the risk of ACL injury by increasing knee flexion during a bilateral drop jump task. Increased knee flexion angles after resistance training may indicate a reduced risk for knee injury from improved neuromuscular control, resulting in a softer landing.

Relationship between three-dimensional kinematics of knee and trunk motion during shuttle run cutting

Female athletes are considered to exhibit knee and trunk motion that is characteristic of anterior cruciate ligament (ACL) injury. The aim of this study was to examine the in vivo motion of the trunk and knee during a cutting manoeuvre and determine the relationship between them. All participants (10 male and 10 female college athletes) performed a shuttle run cutting task with the left limb. Trunk inclination (forward and lateral) and knee joint angles (flexion/extension, abduction/adduction, and internal/external tibial rotation) were calculated. Differences between the sexes and associations between knee motion and trunk inclination were examined. An increase in trunk forward inclination was strongly correlated with an increase in knee flexion angle and moderately correlated with a decrease in the excursion of internal tibial rotation. An increase in right trunk lateral inclination was moderately correlated with an increase in excursion of internal tibial rotation. The results also showed differences between the sexes in trunk forward inclination, lateral inclination, and knee flexion angle, but no such differences in knee abduction or internal tibial rotation. Trunk inclination is related to knee flexion and excursion of internal tibial rotation. Female athletes demonstrate a low trunk forward inclination and knee flexion angle, a posture that resembles that of ACL injury.