Trunk Angle Research Articles

Feasibility of Wearable Haptic Biofeedback Training for Reducing the Knee Abduction Moment During Overground Walking.

Gait modifications are effective in reducing the first peak knee abduction moment (PKAM), a surrogate for knee loading. Reliance on 3D motion capture currently restricts these modifications to the laboratory. Therefore, our purpose was to test the feasibility of a novel wearable biofeedback system to train (1) toe-in and trunk lean modifications and (2) combined toe-in and trunk lean modifications to reduce PKAM during overground walking outside of the laboratory. Twelve healthy participants practiced modifications in a university hallway directly after performing five normal walking trials. The wearable feedback system provided real-time haptic biofeedback during training trials to inform participants if they were within the prescribed modification range (7-12 deg greater than baseline). Participants were instructed to move to the next modification only once they felt comfortable and could perform it with minimal errors. Following training, five trials of each modification were immediately performed in the gait laboratory without feedback. All participants successfully modified their foot progression and trunk angle using the wearable system. At post-test, PKAM decreased from baseline by 62%, 55%, and 28% during combined, trunk leanand toe-in gait, respectively. The wearable feedback system was effective to modify participants' foot and trunk angle by the prescribed amount, resulting in reduced PKAM during all modifications at post-test. Participants were also able to perform a combined modification, although it took longer to report feeling comfortable doing so. This study demonstrates that a wearable feedback system is feasible to modify kinematic parameters and train gait modifications outside the laboratory.

3D trunk orientation measured using inertial measurement units during anatomical and dynamic sports motions.

Trunk motion is related to the performance and risk of injuries during dynamic sports motions. Optical motion capture is traditionally used to measure trunk motion during dynamic sports motions, but these systems are typically constrained to a laboratory environment. Inertial measurement units (IMUs) might provide a suitable alternative for measuring the trunk orientation during dynamic sports motions. The objective of the present study was to assess the accuracy of the three‐dimensional trunk orientation measured using IMUs during dynamic sports motions and isolated anatomical trunk motions. The motions were recorded with two IMUs and an optical motion capture system (gold standard). Ten participants performed a total of 71 sports motions (19 golf swings, 15 one‐handed ball throws, 19 tennis serves, and 18 baseball swings) and 125 anatomical trunk motions (42, 41, and 42 trials of lateral flexion, axial rotation, and flexion/extension, respectively). The root‐mean‐square differences between the IMU‐ and optical motion capture‐based trunk angles were less than 5 degrees, and the similarity between the methods was on average across all trials “very good” to “excellent” (R ≥ 0.85; R 2 ≥ 0.80). Across the dynamic sports motions, even higher measures of similarity were found (R ≥ 0.90; R 2 ≥ 0.82). When aligned to the relevant segment, the current IMUs are a promising alternative to optical motion capture and previous presented IMU‐based systems for the field‐based measurement of the three‐dimensional trunk orientation during dynamic sports motions and the anatomical trunk motions.

Does Strategy of Downward Stepping Stair Due to Load of Additional Weight Affect Lower Limb's Kinetic Mechanism?

This study measured the downward stepping movement relative to weight change (no load, and 10%, 20%, 30% of body weight respectively of adult male (n=10) from standardized stair (rise of 0.3 m, tread of 0.29 m, width of 1 m). The 3-dimensional cinematography and ground reaction force were also utilized for analysis of leg stiffness: Peak vertical force, change in stance phase leg length, Torque of whole body, kinematic variables. The strategy heightened the leg stiffness and standardized vertical ground reaction force relative to the added weights (p<.01). Torque showed rather larger rotational force in case of no load, but less in 10% of body weight (p<.05). Similarly angle of hip joint showed most extended in no-load, but most flexed in 10% of body weight (p<.05). Inclined angle of body trunk showed largest range in posterior direction in no-load, but in vertical line nearly relative to added weights (p<.001). Thus the result of the study proved that downward stepping strategy altered from height of 30 cm, regardless of added weight, did not affect velocity and length of lower leg. But added weight contributed to more vertical impulse force and increase of rigidity of whole body than forward rotational torque under condition of altered stepping strategy. In future study, the experimental on effect of weight change and alteration of downward stepping strategy using ankle joint may provide helpful information for development of enhanced program of prevention and rehabilitation on motor performance and injury.

Linear and Non-linear Dynamic Methods Toward Investigating Proprioception Impairment in Non-specific Low Back Pain Patients.

Central nervous system (CNS) uses vision, vestibular, and somatosensory information to maintain body stability. Research has shown that there is more lumbar proprioception error among low back pain (LBP) individuals as compared to healthy people. In this study, two groups of 20 healthy people and 20 non-specific low back pain (NSLBP) participants took part in this investigation. This investigation focused on somatosensory sensors and in order to alter proprioception, a vibrator (frequency of 70 Hz, amplitude of 0.5 mm) was placed on the soleus muscle area of each leg and two vibrators were placed bilaterally across the lower back muscles. Individuals, whose vision was occluded, were placed on two surfaces (foam and rigid) on force plate, and trunk angles were recorded simultaneously. Tests were performed in eight separate trials; the independent variables were vibration (four levels) and surface (two levels) for within subjects and two groups (healthy and LBP) for between subjects (4 × 2 × 2). MANOVA and multi-factor ANOVA tests were done. Linear parameters for center of pressure (COP) [deviation of amplitude, deviation of velocity, phase plane portrait (PPP), and overall mean velocity] and non-linear parameters for COP and trunk angle [recurrence quantification analysis (RQA) and Lyapunov exponents] were chosen as dependent variables. Results indicated that NSLBP individuals relied more on ankle proprioception for postural stability. Similarly, RQA parameters for the COP on both sides and for the trunk sagittal angle indicated more repeated patterns of movement among the LBP cohort. Analysis of short and long Lyapunov exponents showed that people with LBP caused no use of all joints in their bodies (non-flexible), are less stable than healthy subjects.

Clinical analysis of reconstruction of lateral wall and femoral moment in the treatment of Evans Jensen type V intertrochanteric fracture

To investigate the clinical effect of proximal femoral nail anti rotation (PFNA) and titanium plate in the treatment of Evans Jensen type V intertrochanteric fractures. From October 2013 to March 2016, 30 patients with Evans Jensen type V intertrochanteric fractures were analyzed. According to the operation methods, they were divided into two groups:16 cases of closed reduction and PFNA internal fixation;14 cases of small incision incision reconstruction of titanium plate reconstruction of femoral moment and lateral wall PFNA internal fixation. The operation (blood loss, operation duration), postoperative rehabilitation (postoperative ambulation time, bone healing time), operation related complications (internal fixation fracture, withdrawal, spiral blade cutting out) were observed and compared between the two groups. Harris score of hip joint function was performed 12 months after operation, and the loss degree of cervical trunk angle was observed and compared. All the 30 patients were followed up for 12 to 18 months. The blood loss and operation duration of open reduction group were significantly greater than those of closed reduction group (P<0.05). The postoperative ambulation time, bone healing time, operation related complications, Harris score of hip joint function and loss of cervical trunk angle in the open reduction group were better than those in the closed reduction group(P<0.05). Evans Jensen was treated with PFNA intramedullary fixation through reduction and fixation of femoral moment and lateral wall with reconstruction titanium plate Vtype intertrochanteric fracture can restore the support of femoral moment and lateral wall to femoral head and neck, improve the stability of fracture end and internal fixation after operation, and reduce the risk of fracture end displacement, internal fixation loosening, cutting out and even fracture after treatment with PFNA alone. To shorten the bed time of elderly patients and reduce the operation related complications, it provides a new idea and method for the treatment of Evans Jensen type V intertrochanteric fracture.

Improvement in trunk kinematics after treadmill-based reactive balance training among older adults is strongly associated with trunk kinematics before training

Reactive balance training (RBT) is an emerging fall prevention exercise intervention for older adults. To better understand factors that influence improvements after RBT, the goal of this study was to identify key factors that strongly associate with training-induced improvements in reactive balance. This study is a secondary analysis of data from a prior study. Twenty-eight residents of senior housing facilities participated, including 14 RBT participants and 14 Tai Chi participants (controls). Before and one week after training, participants completed balance and mobility tests and a reactive balance test. Reactive balance was operationalized as the maximum trunk angle in response to standardized trip-like perturbations on a treadmill. Bivariate (Pearson) correlation was used to identify participant characteristics before RBT and measures of performance during RBT that associated with training-induced changes in maximum trunk angle. Maximum trunk angle before reactive balance training exhibited the strongest association with training-induced changes in maximum trunk angle among RBT participants (r2 = 0.84; p < .001), but not among Tai Chi participants (r2 = 0.17; p = .138). Measures of performance during RBT, based upon perturbation speed, also associated with RBT-induced improvements in maximum trunk angle. These results help clarify the characteristics of individuals who can benefit from RBT, and support the use of treadmill perturbation speed as a surrogate measure of training-induced improvements in trunk kinematics.

Biomechanical comparisons of back and front squats with a straight bar and four squats with a transformer bar

ABSTRACT The purpose was to quantify trunk and lower extremity biomechanics among back and front squats with a straight bar and four squats with different anterior-posterior load placements imposed by a transformer bar. Ten males and eight females performed six squat conditions: back and front squats with a straight bar, back and front squats with a transformer bar, and squats with more posteriorly or anteriorly placed loads with a transformer bar. A constant load of 70% of the participant’s one-repetition maximum in the straight-bar front squat was used. Kinematic and kinetic data were collected to quantify joint biomechanics at an estimated parallel squat position in the descending and ascending phases. Squats with more anteriorly placed load significantly decreased trunk flexion and pelvis anterior tilt angles with large effect sizes but increased low-back extension moments with medium to large effect sizes. Hip, knee, and ankle extension moments were generally similar among most conditions. Participants adjusted their trunk and pelvis to mediate the effects of load placements on low-back and lower extremity moments. While lower extremity loading was similar among different squats, the different trunk and pelvis angles and low-back moments should be taken into consideration for people with low-back impairment.

Photographic sagittal plane analysis and its clinical correlation after surgery for adult spinal deformity: a preliminary study.

The aim of this study is to determine the correlation between photographic sagittal parameters and patient-reported outcome measures (PROM) results in adult patients operated on spinal deformity. Non-concurrent prospective study. age at surgery older than 25, minimum 2-year follow-up after a 5 or more level fusion for adult spinal deformity (ASD). Full body lateral standing photographs were taken with adhesive markers placed on ten bony landmarks. SRS-22 and SF-36 questionnaires were completed for every patient. The following photographic parameters were measured: lumbar angle, lumbar curve, thoracic inclination (TI), trunk angle, pelvic tilt, head angle, neck angle, cervicothoracic angle, lumbar vector angle (LVA), dorsal vector angle (DVA), cervical vector angle (CVA), cranial pelvic angle (CrPA), cranial sacral angle (CrSA), fibular inclination angle (FIA) and cranial sagittal vertical axis measured to sacrum (Cr-S), greater trochanter (Cr-GT), knee (Cr-K) and ankle (Cr-A). 65 patients (58 female) operated on ASD in a single institution were included. Age at surgery was 61years (26-67). Postoperative follow-up was 53months (24-120). Spearman rank order test showed several significant (p ≤ 0.01) correlations. After multivariate linear regression analysis age, LVA and TI remained as predictors for SRS image scores (corrected r2 0.41), LVA for SRS satisfaction (corrected r2 0.27), CrPA and age for SRS total scores (corrected r2 0.33), FIA and age for SF36 physical functioning (corrected r2 0.36) and CrSA for SF36 role physical (corrected r2 0.14). Some sagittal photographic parameters may predict mid-term clinical results after ASD surgery.

Classification of Whole-Body Postural Discomfort Using Cluster Analysis.

The objectives of this study were to evaluate the effect of gender and postures of the neck, trunk, and knee on overall postural discomfort, and to classify combined postures into different postural discomfort groups. A total of 95 participants (42 males and 53 females) performed 45 different static postures, which were a combination of 3 neck angles, 5 trunk angles, and 3 knee angles, and rated the perceived postural discomfort. Non-hierarchical K-means cluster analysis was employed to classify the 45 different combined postures into several postural discomfort groups. Postural discomfort was significantly affected by gender and postures of the neck, trunk, and knee (p < 0.001). Three clusters (high, medium, and low discomfort) were identified and the postural discomfort was significantly different between clusters (p < 0.001). The high discomfort group consisted of mostly males with high knee and trunk flexion angles and a moderate neck flexion angle. The low discomfort group was female-dominant with low neck and trunk flexion angles and a moderate knee flexion angle. The different flexibility (stiffness) of the joint motions between genders may affect the gender difference in postural discomfort. The knee and trunk postures were critical to the postural balance, which may affect the perception of whole-body discomfort. This result will be useful for developing and improving postural observation tools.

Inter-rater reliability of an inertial measurement unit sensor-based posture-matching method: A pilot study

Posture quantification is important for analyzing trunk and upper extremity loading and estimating the risk of work-related musculoskeletal disorders. This study introduced an inertial measurement unit sensor-based posture-matching (ISPM) method. The ISPM method is the concept that involves observers wearing sensors and simulating postures in photos or videos obtained at job sites to assess the postural risks for the trunk and upper extremity. We tested the inter-rater reliability of the method in 4 novice observers. For the trunk, shoulder/elbow, and wrist joint angle category, weighted kappa scores were 0.89, 0.52, and 0.26, respectively. The results of the ISPM method indicated moderate or high inter-rater reliability for trunk flexion, shoulder flexion/extension, shoulder abduction/adduction, and elbow flexion. The ISPM method was more reliable than conventional observation-based posture assessment tools used for trunk posture analyses. However, the assessment of upper extremity angles indicated that the reliability of ISPM was lower than that of conventional observation-based posture assessment tools. This was a proof-of-concept study conducted using a few samples. Therefore, further testing is necessary to support the findings. Relevance to industryThe ISPM method requires a minimal level of training. It uses conventional video recording and imposes almost no interruptions to the workers’ performance. The ISPM method showed moderate inter-rater reliability for the trunk, shoulder flexion/extension, shoulder abduction/adduction, and elbow flexion during the joint angle analysis.

Biomechanical assessment while using production tables on mast climbing work platforms

The objective of this study was to assess the impact of using alternative mast climbing work platform (MCWP) designs on trunk motion and postural stability with masonry workers while performing bricklaying and stepping down tasks using a conventional MCWP setting (i.e. with a step deck) as well as two types of production tables (straight- and L-shaped). The trunk angles and postural sway parameters of twenty-five masonry workers were recorded for the following tasks: (1) standing on a simulated MCWP and laying bricks on an adjacent wall, and (2) stepping down onto the step deck to get into position for doing the bricklaying task. Results indicated that the use of the L-shaped production table resulted in the lowest trunk ranges of motion and significantly reduced the workers' trunk angles in all three planes when compared to both the straight-shaped production table and the conventional approach of not using a production table. Data showed that both body sway velocity and area were significantly reduced when using either one of the production tables. The use of production tables significantly reduced impact sway forces when workers stepped from the main platform to the step deck. The use of production tables on MCWPs improved workers’ postures and overall stability, which could reduce the risk of injury.

Estimating Trunk Angle Kinematics During Lifting Using a Computationally Efficient Computer Vision Method.

A computer vision method was developed for estimating the trunk flexion angle, angular speed, and angular acceleration by extracting simple features from the moving image during lifting. Trunk kinematics is an important risk factor for lower back pain, but is often difficult to measure by practitioners for lifting risk assessments. Mannequins representing a wide range of hand locations for different lifting postures were systematically generated using the University of Michigan 3DSSPP software. A bounding box was drawn tightly around each mannequin and regression models estimated trunk angles. The estimates were validated against human posture data for 216 lifts collected using a laboratory-grade motion capture system and synchronized video recordings. Trunk kinematics, based on bounding box dimensions drawn around the subjects in the video recordings of the lifts, were modeled for consecutive video frames. The mean absolute difference between predicted and motion capture measured trunk angles was 14.7°, and there was a significant linear relationship between predicted and measured trunk angles (R2 = .80, p < .001). The training error for the kinematics model was 2.3°. Using simple computer vision-extracted features, the bounding box method indirectly estimated trunk angle and associated kinematics, albeit with limited precision. This computer vision method may be implemented on handheld devices such as smartphones to facilitate automatic lifting risk assessments in the workplace.

Comprehensive description of sit-to-stand motions using force and angle data

A normative description of a motion details the necessary and sufficient criteria to identify that motion. It equips researchers with a shared lexicon for describing their research and, in this way, adoption of a normative description facilitates communication within the research community. Although there is an abundance of descriptions of sit-to-stand movement, there is not a commonly accepted normative description of sit-to-stand; study-specific descriptions are commonplace. This work evaluates the breadth of existing sit-to-stand descriptions using new experimental data from 15 healthy young adults standing from a 46 cm chair. Our goal is to develop a normative description of the sit-to-stand motion that is in harmony with the literature. After aligning experimental data to seat-off (the one sit-to-stand event with a clear definition), events defining the start of sit-to-stand, seat-off, and the end of sit-to-stand are identified using a density-based clustering method. Then, the intermediary events of start of seat unloading, end of momentum transfer, and beginning of stabilization are determined while maintaining consistent sequencing and biomechanical meaning. These six events of sit-to-stand are determined from trunk, hip, knee, and ankle angle data and vertical ground reaction forces. The events are in greatest accordance with the descriptions of sit-to-stand introduced by Schenkman et al. (1990) and Kralj et al. (1990), and the event timings are in alignment with the findings of other researchers. The proposed description of healthy sit-to-stand promotes consistency in the description of this motion and adoption of this description will promote effective communication in sit-to-stand research.

Assessment of Joint Angle and Reach Envelope Demands Using a Video-Based Physical Demands Description Tool.

Current methods for describing physical work demands often lack detail and format standardization, require technical training and expertise, and are time-consuming to complete. A video-based physical demands description (PDD) tool may improve time and accuracy concerns associated with current methods. Ten simulated occupational tasks were synchronously recorded using a motion capture system and digital video. The tasks included a variety of industrial tasks from lifting to drilling to overhead upper extremity tasks of different cycle times. The digital video was processed with a novel video-based assessment tool to produce 3D joint trajectories (PDAi), and joint angle and reach envelope measures were calculated and compared between both data sources. Root mean squared error between video-based and motion capture posture estimated ranged from 89.0 mm to 118.6 mm for hand height and reach distance measures, and from 13.5° to 21.6° for trunk, shoulder, and elbow angle metrics. Continuous data were reduced to time-weighted bins, and video-based posture estimates showed 75% overall agreement and quadratic-weight Cohen's kappa scores ranging from 0.29 to 1.0 compared to motion capture data across all posture metrics. The substantial level of agreement between time-weighted bins for video-based and motion capture measures suggest that video-based job task assessment may be a viable approach to improve accuracy and standardization of field physical demands descriptions and minimize error in joint posture and reach envelope estimates compared to traditional pen-and-paper methods.

스마트폰 사용 시 체간의 각도가 폐활량에 미치는 영향

스마트폰 사용 시 체간의 각도가 폐활량에 미치는 영향

Flexibility Measurement Affecting the Reduction Pattern of Back Muscle Activation during Trunk Flexion

Numerous studies have been conducted on lower back injury caused by deeper stooped posture, which is associated with the back muscle flexion–relaxation phenomenon (FRP). Individual flexibility also affects FRP; individuals with high flexibility have the benefit of delayed FRP occurrence. This study attempted to determine the most efficient measurement of flexibility for evaluating the occurrence and degree of FRP when participants flexed their trunk forward. We recruited 40 male university students who were grouped on the basis of three flexibility measurements (toe-touch test, TTT; sit-and-reach test, SRT; modified Schober’s test, MST) into three levels (high, middle and low). Muscle activation (thoracic and lumbar erector spinae, TES and LES, respectively; hamstring, HMS) and lumbosacral angle (LSA) were recorded when the trunk flexed forward from 0° (upright) to 15°, 30°, 45°, 60°, 75° and 90°. The results indicated that trunk angle had a significant effect on three muscle activation levels and LSA. The effects of muscles and LSA varied depending on flexibility measurement. TTT significantly discriminated LES electromyography findings between high and low flexibility groups, whereas MST and SRT distinguished between high and non-high flexibility groups. The TTT values positively correlated with the time of LES FRP occurrence, showing that the higher the TTT, the slower the occurrence of FRP. This is beneficial in delaying or avoiding excessive loading on the passive tissue of the lumbar spine when performing a deeper trunk flexion.

Biomechanical analysis of upper trapezius, erector spinae and brachioradialis fatigue in repetitive manual packaging tasks: Evidence from Chinese express industry workers

This study aims to assess the effects of repetitive motion-induced fatigue during manual packaging on kinematics and muscle activity of the arm, back and shoulder. Eighteen participants performed a 60-min manual packaging task. Electromyography median frequency of RUT, RES, LES and RB decreased by 13.2% (p < 0.05), 12.8% (p < 0.05), 11.3% (p < 0.05) and 21% (p < 0.001), respectively over time. The head flexion and the right upper arm flexion angles significantly (p < 0.001) differed among different packaging sizes, and similar results were observed for left upper arm flexion and rotation. The trunk and pelvis angles significantly (p < 0.05) differed over time under three kinds of packaging. The results showed there was an increase in the rating of perceived exertion from 8.56 to 16.94 (p<0.01) during the task. The outcomes of this study indicate repetitive movements in the manual packaging task resulted in elevated prevalence of muscle discomfort in packaging workers, especially the right brachioradialis. Interventions such as specific work: rest ratios, workplace redesign should be explored to relieve muscle fatigue and discomfort. Relevance to industryFor workers performing repetitive manual packaging tasks, biomechanical analysis of different muscles groups can help in developing appropriate ergonomic interventions.

On the effect of changing handgrip position on joint specific power and cycling kinematics in recreational and professional cyclists.

IntroductionIn cycling, the utilization of the drops position (i.e. the lowest handlebar position relative to the ground) allows for reduced frontal area, likely improved aerodynamics and thus performance compared to the tops (i.e. the position producing the most upright trunk). The reduced trunk angle during seated submaximal cycling has been shown to influence cardiorespiratory factors but the effects on pedalling forces and joint specific power are unclear. The purpose of this study was to investigate the effect of changing handgrip position on joint specific power and cycling kinematics at different external work rates in recreational and professional cyclists.MethodNine professional and nine recreational cyclists performed cycling bouts using three different handgrip positions and three external work rates (i.e. 100W, 200W and external work rate corresponding to the lactate threshold (WRlt)). Joint specific power was calculated from kinematic measurements and pedal forces using 2D inverse dynamics.ResultsWe found increased hip joint power, decreased knee joint power and increased peak crank torque for the professional cyclist compared to the recreational cyclists, but only at WRlt where the professional cyclists were working at a higher external work rate. There was no main effect of changing handgrip position on any joint, but there was a small interaction effect of external work rate and handgrip position on hip joint power contribution (Generalized eta squared (ηg2) = 0.012). At 100W, changing handgrip position from the tops to the drops decreased the hip joint contribution (-2.0 ± 3.9 percentage points (pct)) and at the WRlt, changing handgrip position increased the hip joint power (1.6 ± 3.1 pct). There was a small effect of handgrip position with the drops leading to increased peak crank torque (ηg2 = 0.02), increased mean dorsiflexion (ηg2 = 0.05) and increased hip flexion (ηg2 = 0.31) compared to the tops.DiscussionThe present study demonstrates that there is no main effect of changing handgrip position on joint power. Although there seems to be a small effect on hip joint power when comparing across large ranges in external work rate, any potential negative performance effect would be outweighed by the aerodynamic benefit of the drops position.

Effect of Carrying Two Types of Packs in Two Heights of Placement (Lumbar and Thoracic) on some Kinematics Variables of Primary Schoolboys

Introduction: The present study is conducted with the aim to investigating the effect of carrying backpacks and modified packs (with three bags that distribute the load equally in front and back of trunk) in two heights of placement including lumbar and thoracic, on craniovertebral angle, trunk angle, and the angle of hip and knee joints among the 8-11-year-old schoolboys during walking. Materials and Methods: Considering the inclusion and exclusion criteria, 27 schoolboys participated in the study and fulfilled five tasks including walking without a pack, carrying backpack on lumbar area, backpack on thoracic area, modified packs on lumbar area, and modified packs on thoracic area. Then, the photogrammetry of the right side was performed by a camera (Panasonic, Japan). The target angles were measured as single-blind with Kinovea motion analysis software. Repeated measure analysis of variance (ANOVA) was used to compare tasks. Results: The results showed significant decrease in craniovertebral angle (increased forward head posture) in the task of carrying backpacks on thoracic area in contrast with the lumbar area, as well as increase in trunk forward lean while carrying packs (P 0.05). Conclusion: Carrying packs on lumbar area caused less postural variations, thus seeming better. Changing the position of the load concentrated on the back can more affect the kinematic parameters of schoolboys. The modified pack carriage only caused a little trunk forward lean which was lesser than that of backpack carriage, so it can be a good alternative for students’ backpack.

Limited Support for Trunk and Hip Deficits as Risk Factors for Athletic Knee Injuries: A Systematic Review With Meta-analysis and Best-Evidence Synthesis.

To determine whether neuromuscular deficits in trunk and hip-related function are risk factors for athletic knee injuries. Etiology systematic review with meta-analysis. Six online databases (MEDLINE, Web of Science, Embase, CINAHL, Scopus, and SPORTDiscus) were searched up to April 2019. Studies assessing trunk and hip neuromuscular function as risk factors for knee injuries in healthy athletic populations were included. Outcomes were synthesized quantitatively using meta-analysis of odds ratios, and qualitatively using best-evidence synthesis. Twenty-one studies met the inclusion criteria. There was very low-certainty evidence that greater hip external rotation strength protected against knee injuries (odds ratio = 0.78; 95% confidence interval: 0.70, 0.87; P<.05). There was limited evidence that deficits in trunk proprioception and neuromuscular control, and the combination of excessive knee valgus and ipsilateral trunk angle when landing unilaterally from a jump, may be risk factors for knee injuries. Most variables of trunk and hip function were not risk factors for injuries. Further research is required to confirm whether hip external rotation strength, trunk proprioception and neuromuscular control, and the combination of knee valgus angle and ipsilateral trunk control are risk factors for future knee injuries. J Orthop Sports Phys Ther 2020;50(9):476-489. Epub 1 Aug 2020. doi:10.2519/jospt.2020.9705.