Brace Conditions Research Articles

Behavior of Extended Single-Plate Shear Connections Subjected to Combined Shear and Compression Forces Using Finite Element Analysis

Extended single-plate shear connections can be subjected to compression loads in addition to shear loads during extreme events like wind and earthquakes. However, the existing interaction equations found in the AISC Steel Construction Manual, in literature, and in design examples—which are being used in design for combined loading cases—have not been formally validated for use by experimental testing or finite element analysis. This research aims to study the behavior of these connections when subjected to combined loading of shear and compression force by performing a nonlinear finite element analysis in ABAQUS. The variables considered in the study are column web stiffness, connection configurations, and different bracing conditions of the beam. The results from these analyses were compared to the available interaction equations in the AISC Manual and in literature to assess their applicability under different conditions. Shear-compression interaction plots were generated from the results that show the shear strength decreases with an increase in compression force in the connection. The effect of the compression force on the shear strength depends on the column web’s rigidity and the bracing condition of the beam.

An evaluation of front seat distance from rear facing child restraint systems in prevention of injury in frontal crash tests

Objectives Elevated head injury incidence in infants compared to toddlers involved as occupants in motor vehicle crashes has been demonstrated in multiple population-representative crash databases. Further, experimental studies have revealed a potential injury mechanism via impact between a rear-facing, CRS-restrained child and the back of the vehicle seat or console on the row in front of the CRS. Subsequently, experimental studies have suggested that bracing the CRS against the seat immediately in front of the CRS could mitigate head injury, but also indicated that more research was necessary. Thus, we investigated the effect of bracing against the front seat, as well as distance from the front seat with rear-facing infant carriers and rear-facing convertibles, with a focus on changes to measured head, neck and chest injury metrics in rear facing CRSs. Further, we examined the effect of using the infant carrier with and without a base on these injury metrics. Methods 34 frontal sled tests at 30 or 35 mph were conducted using a simulated rear-row vehicle seat and structure representing the front seatback. A Q1.5 anthropomorphic test device (ATD) was placed in a single make/model LATCH-affixed rear-facing convertible or single make/model infant carrier; infant carrier without base was affixed with lap and shoulder belt. To evaluate the effect of bracing and distance, tests were conducted with a 300, 140, 70, or 15 mm gap between the CRS seatback and the front seatback, or a touching (0 mm) or braced (-20 mm) condition. Bayesian regression models quantified the effects of various predictors and model uncertainty. Results For tests with the convertible CRS, no head contact was observed between the head and the front vehicle seatback. For the infant carrier, head contact occurred at both 70 and 140 mm distances but not the other distances. On average, the −20, 0, or 15 mm distances yielded a 60% reduction in head injury criterion with 15 millisecond window (HIC15), and a 60% to 80% reduction in neck tension, compared to the 70 and 140 mm distances; chest acceleration also decreased for the convertible seat only. In the case of both carriers and convertibles, each mm of distance the CRS moves away from the front seatback up to 70 mm, adds 5.3 HIC15 points (95% Credible Interval (CrI):[4.6, 6.2]), and 3.5 Newtons (95% CrI: [2.2, 4.8]) of neck tension, on average. Conclusions Placing a rear facing CRS, both convertibles and infant carriers, against or close to the seatback of the seat immediately in front of the CRS reduces head and tensile neck injury criteria in ATDs. The amount of gap between the front seat and the rear facing CRS is strongly and positively correlated with HIC for both convertibles and infant carriers. RF infant carriers with and without a base yield comparable injury metrics and kinematics when touching or nearly touching the back of the front vehicle seatback.

Utilization of Short Span Web-Tapered Beams Using Flexible Nodal Bracing

For many years member with varying cross-sectional dimensions along the length have been widely used in steel structures. The use of nodal braces to enhance the load-carrying capacity and stability of these elements is prevalent. These supports ensure structural stability by regulating the distribution of loads within the structural system while also enhancing the structure's resistance to lateral loads. Presently, the design of these nodal braces are carried out according to requirements outlined in Design Guide 25 and AISC Specification (2022). However, these standards offer a general framework for elements with fixed brace conditions and prismatic cross-section. This study aims to be a pioneering investigation into the variation of brace force values in short-span and compact web-tapered beams under different loading conditions. The article seeks to comprehensively examine the requirements and limits of brace force in short-span web-tapered compact beams. To achieve this goal, parametric finite element analyses is utilized to explore how brace force changes concerning beam geometry, material properties, and loading conditions. The beam used was considered as doubly symmetric and divided into 100 nodes and supported by a nodal brace at the middle node. The beam is 50 inches long, tapering from 42 inches to 36.40 inches over its span of 100 nodes. In terms of finite element analysis, the software utilized significantly influences the accuracy and reliability of results, particularly in scenarios involving inelastic nonlinear analysis. In this study, the Abaqus program was employed specifically to conduct parametric finite element analyses, considering the complexities of inelastic material behavior. The findings of this research are intended to contribute to the development of a new design method for determining the requirements and limits of brace force in short-span and variable cross-sectional dimension compact beams. Consequently, the aim is to enable the safe and economical design of such beams, providing engineers with ideas to consider and data to utilize in their designs.

IMMEDIATE EFFECT OF CUSTOM-MADE BOSTON-TYPE THORACO-LUMBO-SACRAL ORTHOSIS ON BALANCE AND POSTURAL STABILITY IN ADOLESCENT IDIOPATHIC SCOLIOSIS

Adolescent idiopathic scoliosis (AIS) can impair postural stability and balance functions. Boston brace systems with varying external corrective force strategies are used as one of the common conservative treatments in AIS. Although multiple studies have found that various orthotic therapies enhance curve advancement, the effects of spinal bracing on postural equilibrium and stability remain unknown. The primary objective of this study was to examine the effect of the immediate use of custom-made Boston-type thoraco-lumbo-sacral orthosis (TLSO) on balance and postural stability in AIS. Postural balance using the center of pressure (CoP) measures was measured by the HUMACⓇ Balance & Tilt System (CSMi, Stoughton, MA). The line laser tool (Bosch, GLL 3 X P, Stuttgart, Germany) was used for measuring the decompensation distance for postural evaluation. The balance parameters such as stability score (%), path length (cm), average velocity (cm/s), and compensation–decompensation for posture were evaluated and compared between brace-on and brace-off conditions. Improvement of standing posture indicates spinal symmetry and cosmesis whereas enhancement of static balance was statistically nonsignificant ([Formula: see text] > 0.05). Although the mean stability score, path length and average velocity of CoP in braced condition (91.4 ± 4.57, 115.62 ± 22.34 cm and 1.05 ± 0.12 cm/s) was found to be improved than unbraced condition (90.5 ± 5.09, 121.46 ± 35.52 cm and 1.11 ± 0.24 cm/s), the results were nonsignificant ([Formula: see text] = 0.078, 0.425 and 0.263). The scoliotic compensation was improved in the braced condition (0.64 ± 0.60 cm) compared to brace-off condition (1.74 ± 0.61 cm) showing improved posture ([Formula: see text] = 0.00013). Wearing the custom-made Boston-type TLSO showed positive effects on static posture and mean balance parameters. In future studies, the long-term effectiveness of this brace should be examined in patients with different spinal curve patterns and degrees of scoliosis.

The effect of age and bracing on vehicle occupant responses during sled-simulated evasive swerving

Objective Bracing can reduce adult occupants’ out-of-position postures, but it is unclear if this finding can be extended to child occupants. We investigated the effect of bracing, and age on the motion of vehicle occupants of different ages during sled-simulated pre-crash maneuvers. Methods Forty seatbelt restrained subjects (9–40 y.o.) experienced sled simulated evasive swerving maneuvers during a brace condition, where subjects actively brace before the maneuver onset, and an unbraced condition. A 3D motion capture system, electromyography (EMG), and seatbelt load cells captured head and trunk kinematics, muscle activation, and seat belt reaction forces, respectively. The effects of age and bracing on peak lateral head and trunk displacement were examined with Mixed Effects Model (p ≤ 0.05). Results In the braced condition, all subjects had reduced normalized peak head (0.09 ± 0.05) and trunk (0.11 ± 0.05) displacements compared to the unbraced condition (Head: 0.14 ± 0.06, Trunk: 0.17 ± 0.07) (p < 0.05). For the into-the-belt direction in the unbraced condition, children showed the smallest peak head and trunk displacement of all age groups (p < 0.01) while teens had the greatest peak head and trunk displacement compared to all other age groups (p < 0.02). Similar trends were found in the out-of-the-belt direction in the unbraced condition (p < 0.01). In the unbraced condition, all occupants showed greater shoulder seat belt reaction loads than the braced condition (unbraced 1.6–2.7 N/kg, braced 1.0–1.4 N/kg). Children also showed greater neck muscle activation (50–64% MVIC) compared to other muscles and older occupants regardless of the bracing condition or direction of motion. Conclusion Bracing reduced out-of-position postures across all ages. In the unbraced condition, children move less than teens and adults due to greater activation in the neck muscles. In the unbraced condition, teens showed the greatest motion, potentially due to their developing neuromotor control transitioning to a more mature stage. Across all age groups in the unbraced condition, occupants relied more heavily on the seat belt to maintain their position rather than their muscles to brace, suggesting the importance of good seatbelt-torso interaction in unbraced occupants.

Comparative analysis of Boston and Cheneau braces in treating scoliosis: A 2-year follow-up study on curve reduction

BackgroundScoliosis, characterized by the lateral curvature of the spine, impacts the spine's alignment in three dimensions. Braces are commonly employed as a conservative treatment for individuals with scoliosis, particularly those with curves ranging from 20 to 40 degrees. This treatment approach's primary objectives include arresting the deformity's progression, enhancing clinical appearance, alleviating pain, improving overall quality of life, and circumventing the need for surgical intervention. The aim of this study was to compare the effectivences of Boston and Cheneau braces in individuals with scoliosis. MethodsIn this retrospective study, 51 subjects were included and monitored over two years. The primary parameters under evaluation encompassed the severity of both primary and secondary curves and compliance with the prescribed treatment. The subjects were classified into two groups: those utilizing the Cheneau brace and those employing the Boston brace. ResultsThe initial mean values of the primary and secondary curves during the first visit were 37.6 (±7.4) and 30.1 (±9.7) degrees, respectively. However, the in-brace curve measurements for the primary and secondary curves were 31.5 (±1.3) and 22.3 (±13.3) degrees, respectively (p-value = 0.0). The mean compliance values of subjects using Boston and Cheneau braces were 16.8 and 17.3 hours per day, respectively (p-value = 0.1). No significant difference was observed in the correction achieved with the Boston and Cheneau braces during the follow-up period. ConclusionsThe results of this study demonstrated a significant reduction in the scoliotic curve while under brace conditions. However, the degree of correction achieved did not significantly differ during the follow-up periods. Additionally, there was no notable variance in the correction obtained between the Boston and Cheneau braces. Short summaryBrace treatment can result in a significant reduction in the scoliotic curve. There was no noticeable difference in the correction achieved between the Boston and Cheneau braces. The degree of curve correction achieved by brace treatment did not vary significantly during the follow-up periods.

Effect of thoracolumbosacral braces on running ground reaction force components in male individuals with kyphosis

Background & aimsBraces are one of the methods for kyphosis treatment, but they can relocate the center of gravity of the trunk, affecting the ground reaction force (GRF) during running. Therefore, this study aimed to investigate the effects of two types of thoracolumbosacral braces on running GRF components in individuals with kyphosis. Materials & methodsParticipants were 15 males diagnosed with kyphosis who volunteered in this quasi-experimental study. Each subject performed the barefoot running trials on the force plate with one simple brace, with a sensor brace, and without the brace condition. The ground reaction forces components were calculated in the stance phase. Statistical analysis was done with repeated measures test with a significant level of 0.05. ResultsPeak medial ground reaction force when running with a sensor brace was lower than running with a simple brace (p = 0.017). Free moments were similar during three running conditions (p > 0.05). ConclusionLower maximum medial ground reaction force while using a sensor brace may possibly demonstrate the beneficial effects of a sensor brace in individuals with kyphosis.

Effects of Prophylactic Lace-Up Ankle Braces on Kinematics of the Lower Extremity During a State of Fatigue

Background: Prophylactic lace-up braces are commonly used in athletics regardless of ankle injury history to reduce lateral ankle sprains (LAS). Objectives: The purpose of the study was to assess ankle and knee kinematics associated with chronic knee pathologies during a 90° cutting maneuver before and after a state of fatigue. Methods: Using a randomized crossover design, thirteen, active adults (6 males and 7 females) engaged in a 15-m beep test fatigue protocol with a 90° cutting maneuver test before and after the fatigue protocol, both with and without brace. Results: Brace condition significantly reduced Ankle Sagittal Displacement (ASD; 52°) compared to no brace condition (62°) (p .05). Peak knee flexion was significantly greater in brace (56°) compared to no brace condition (47°) and, likewise, took longer to reach it (10 ms) (p .05). Conclusions: Prophylactic ankle braces limiting ASD can cause the foot to land in a more dorsiflexed position at initial ground contact causing more rearfoot strike, which may contribute to chronic knee pathologies.

Cold-formed steel strength predictions for torsion and bending–torsion interaction

Locally slender cross-section members, such as cold-formed steel open sections, are susceptible to significant twisting and high warping torsion stresses. Torsion considerations are complicated by whether it is derived as a first-order effect from loading or a second-order effect from instability. Previous direct torsion experiments on lipped Cee sections have shown significant inelastic reserve. Furthermore, the current design for combined bending–torsion interaction has limitations, including only considering the first yield and ignoring the cross-section slenderness in torsion. Two parametric studies were conducted to predict both the torsion capacity and the combined bending–torsion interaction in locally slender cross-sections. Shell finite element analysis of lipped Cee and Zee sections for both the torsion only and the combined bending–torsion cases were created using a validated model. For the torsion-only study, various cross-section geometries, steel grades, and member lengths covering the range of practically expected torsional slenderness were investigated. A set of bimoment parameters, including yield, buckling, and plastic bimoments, were calculated and the ultimate bimoment was determined by shell finite element collapse analyses. A simple uniform equation predicting the bimoment capacity was adopted and two bimoment strength curves are proposed for local and distortional buckling-controlled cases respectively. For the combined bending–torsion case, various practical cross-sections and bracing conditions were investigated with various ratios of applied torsion and bending. Shell finite element buckling and collapse analyses were performed to determine the critical and ultimate moments and bimoments. It was found that the current AISI standard is conservative under most scenarios. Updated torsion–bending interaction equations incorporating bimoment and bending moments are proposed. The interaction equations are dependent on the cross-section, the direction of the applied torsion, and the bracing condition.

Does in-brace correction affect coronal spinal and thoracic cage parameters in individuals with idiopathic scoliosis? A retrospective cohort study.

The aim of the study is to identify the effects of in-brace correction on coronal spinal and thoracic cage parameters in individuals with idiopathic scoliosis (IS). The coronal spinal parameters [Cobb angle, apical vertebral rotation (AVR), lateral trunk shift, coronal alignment, biacromial slope and pelvic asymmetry] and the thoracic cage parameters [T1- 12 height, T1-S1 height, thoracic transverse diameter, and apical vertebral body-rib ratio (AVB-R)] of 89 child and adolescent patients were measured on posterior-anterior full-spine radiographs at pre-brace and in-brace conditions using Surgimap software. The initial in-brace correction (IBC) was calculated as a percentage decrease in the Cobb angle on the in-brace radiographs. The mean IBC rate for the primary curve was 37% (range = 10-100%). In the in- brace condition, the Cobb angle (p<0.001), AVR (p<0.001) and lateral trunk shift (p<0.001) decreased significantly; no statistically significant difference was found in the biacromial slope (p=0.713) and the coronal alignment (p=0.074). The T1-12 height and the T1-S1 height increased significantly (p<0.001) whereas the thoracic transverse diameter and the AVB-R decreased significantly (p<0.001). Unlike IBC rate was below 30% as IBC rate was above 30%, the T1-12 height (p<0.001) increased and the AVB-R decreased (p<0.001). The bracing improved the lateral trunk shift, the AVB-R, the thoracic and spine heights, but decreased the thoracic transverse diameter. The thoracic cage parameters may be better when the IBC rate is above 30%.

Experimental Testing of Post‐installed Anchors for Use in Retrofitting of RC Frame with Steel Braces

AbstractThe retrofitting of deficient Reinforced Concrete (RC) frames, particularly those with strength and stiffness irregularities such as Open Ground Story, has been widely researched. Steel braces are a great option for retrofitting these buildings, but the narrow section sizes of existing beams and columns pose a challenge. However, post‐installed chemical anchors can provide an efficient, cost‐effective solution for connecting such structures with steel braces, provided that they are designed properly to account for all possible failure modes. This study investigates the use of post‐installed chemical anchors to connect steel braces with narrow‐beam column subassemblies in existing low‐ to mid‐rise Open Ground Story buildings. The three experiment are considered to test the bracing conditions with elastic and yielding brace. The gusset plate is designed as per Balanced Design Procedure to obtain an economical section with controlled yielding and failure sequence. The forces on gusset plate are computed using the Uniform Force Method, which helps in designing the post‐installed anchor dimension and spacing. A comparison is drawn between the three test from which it is seen that the chemical anchors perform well in all cases and conventional brace shows expected performance.

The Effects of Cervical Orthoses on Head and Intervertebral Range of Motion.

Prospective Cohort. Quantify and compare the effectiveness of cervical orthoses in restricting intervertebral kinematics during multiplanar motions. Previous studies evaluating the efficacy of cervical orthoses measured global head motion and did not evaluate individual cervical motion segment mobility. Prior studies focused only on the flexion/extension motion. Twenty adults without neck pain participated. Vertebral motion from the occiput through T1 was imaged using dynamic biplane radiography. Intervertebral motion was measured using an automated registration process with validated accuracy better than 1 degree. Participants performed independent trials of maximal flexion/extension, axial rotation, and lateral bending in a randomized order of unbraced, soft collar (foam), hard collar (Aspen), and cervical thoracic orthosis (CTO) (Aspen) conditions. Repeated-measures ANOVA was used to identify differences in the range of motion (ROM) among brace conditions for each motion. Compared with no collar, the soft collar reduced flexion/extension ROM from occiput/C1 through C4/C5, and reduced axial rotation ROM at C1/C2 and from C3/C4 through C5/C6. The soft collar did not reduce motion at any motion segment during lateral bending. Compared with the soft collar, the hard collar reduced intervertebral motion at every motion segment during all motions, except for occiput/C1 during axial rotation and C1/C2 during lateral bending. The CTO reduced motion compared with the hard collar only at C6/C7 during flexion/extension and lateral bending. The soft collar was ineffective as a restraint to intervertebral motion during lateral bending, but it did reduce intervertebral motion during flexion/extension and axial rotation. The hard collar reduced intervertebral motion compared with the soft collar across all motion directions. The CTO provided a minimal reduction in intervertebral motion compared with the hard collar. The utility in using a CTO rather than a hard collar is questionable, given the cost and little or no additional motion restriction.

A Dynamic Ankle Orthosis Reduces Tibial Compressive Force and Increases Ankle Motion Compared to a Walking Boot.

Tibial bone stress injuries are a common overuse injury among runners and military cadets. Current treatment involves wearing an orthopedic walking boot for three to twelve weeks, which limits ankle motion and leads to lower limb muscle atrophy. A Dynamic Ankle Orthosis (DAO) was designed that provides a distractive force that offloads in-shoe vertical force and retains sagittal ankle motion during walking. It remains unclear how tibial compressive force is altered by the DAO. This study compared tibial compressive force and ankle motion during walking between the DAO and an orthopedic walking boot. Twenty young adults walked on an instrumented treadmill at 1.0 m/s in two brace conditions: DAO and walking boot. 3D kinematic, ground reaction forces, and in-shoe vertical force data were collected to calculate peak tibial compressive force. Paired t-tests and Cohen's d effect sizes were used to assess mean differences between conditions. Peak tibial compressive force (p = 0.023; d = 0.5) and Achilles tendon force (p = 0.017; d = 0.5) were moderately lower in the DAO compared to the walking boot. Sagittal ankle excursion was 54.9% greater in the DAO compared to the walking boot (p = 0.05; d = 3.1). The findings from this study indicated that the DAO moderately reduced tibial compressive force and Achilles tendon force and allowed more sagittal ankle excursion during treadmill walking compared to an orthopedic walking boot.

Experimental and Analytical Studies of Continuous Steel-Stringer Lateral-Torsional Buckling Resistance

In the 1950s and 1960s, some Louisiana’s bridges were constructed using steel twin-girder or truss systems, in which floorbeams are carried by the main members and continuous (spliced) stringers are supported by the floorbeams. The main members are either two-edge (fascia) girders or trusses. One of the byproducts of this type of design is that stringer bottom flanges are in compression in the negative moment region over the floorbeams, which could result in lateral torsional buckling (LTB) should inadequate lateral bracing be provided. When the continuous stringers are load-rated using AASHTOWare Bridge Rating analysis software (BrR 7.1), their LTB resistance is calculated in accordance with American Association of State Highway Officials (AASHTO) LRFD Bridge Design Specifications, which do not account for potential bracing provided by a noncomposite deck and could underestimate flexural strength. As a result, the rating may be low enough to require restrictive load posting or even bridge closure. This paper summarizes extensive experimental and numerical studies investigating the behavior of this type of floor system by testing two-span, continuous, steel stringers in a grillage that included three stringer lines, an interior transverse support (floorbeam), and transverse diaphragms at the end supports. The tests and finite-element analysis studies encompassed a variety of unbraced lengths and support conditions with steel diaphragms or timber ties acting as bracing members. The findings demonstrated that, for the systems examined, minimal bracing could substantially enhance LTB resistance and supported the use of higher flexural strengths than those currently predicted using AASHTO Specifications. This paper illustrates the use, challenges, and successes in LTB modeling beams with various support and bracing conditions. The most flexible cases were the most difficult to achieve close agreement with experimental results.

Immediate Effects of Walking With a Knee Brace After Anterior Cruciate Ligament Reconstruction: A Biomechanical, Biochemical, and Structural Approach.

Individuals who undergo anterior cruciate ligament reconstruction (ACLR) are at higher risk of posttraumatic osteoarthritis. Altered joint tissue loading caused by aberrant gait biomechanics leads to deleterious changes in joint health linked to the onset of posttraumatic osteoarthritis. Knee braces have been used to modify joint tissue loading in individuals with joint injury, yet the effects of walking with a brace after ACLR on biomechanical, biochemical, and structural cartilage outcomes are unknown. To compare biomechanical, biochemical, and structural outcomes between braced and nonbraced walking in individuals with ACLR. Crossover study. Research laboratory. A total of 34 individuals with unilateral ACLR (18 females, 16 males; time since ACLR = 50.1 ± 36.8 months). Gait biomechanics were assessed during braced and unbraced conditions on separate days. Vertical ground reaction force, knee-flexion angle, and internal knee-extension moment waveforms were evaluated throughout the stance phase and compared between conditions. Percentage changes in serum cartilage oligomeric matrix protein (%ΔCOMP) and femoral cartilage cross-sectional area (%ΔCSA) measured via ultrasound were calculated after a 3000-step walking protocol. Braced walking increased the knee-flexion angle (largest difference = 3.56°; Cohen d effect size = 1.72) and knee-extension moment (largest difference = -0.48% body weight × height; Cohen d effect size = -1.14) compared with nonbraced walking but did not influence vertical ground reaction force. Whereas no difference (P = .20) in %ΔCOMP existed between the braced and nonbraced conditions in the entire cohort (n = 30 with complete blood data), a larger increase (P = .04) in %ΔCOMP was seen during nonbraced than braced walking in individuals who demonstrated increased COMP during nonbraced walking. No difference (P = .86) in %ΔCSA was present between the braced and nonbraced conditions. Braced walking may improve sagittal-plane gait biomechanics and %ΔCOMP in a subset of individuals who demonstrate a typical increased COMP response to load (ie, increase in COMP) after nonbraced walking.

Biomechanical Analysis of Hip Braces after Hip Arthroscopic Surgery for Femoroacetabular Impingement Syndrome: An Observational Study.

Currently, hip braces are recommended and typically worn by femoroacetabular impingement (FAI) patients after hip arthroscopic surgery. However, there is currently a lack of literature regarding the biomechanical effectiveness of hip braces. The purpose of this study was to investigate the biomechanical effect of hip braces after hip arthroscopic surgery for FAI. Overall, 11 patients who underwent arthroscopic FAI correction and labral preservation surgery were included in the study. Standing-up and walking tasks in unbraced and braced conditions were performed at 3 weeks postoperatively. For the standing-up task, videotaped images of the hip's sagittal plane were recorded while patients stood from a seated position. After each motion, the hip flexion-extension angle was calculated. For the walking task, acceleration of the greater trochanter was measured using a triaxial accelerometer. For the standing-up motion, the mean peak hip flexion angle was found to be significantly lower in the braced condition than in the unbraced condition. Furthermore, the mean peak acceleration of the greater trochanter was significantly lower in the braced condition than in the unbraced condition. Patients undergoing arthroscopic FAI correction surgery would benefit from usage of a hip brace in terms of protecting repaired tissues during early postoperative recovery.

Effects of Using a Shoulder/Scapular Brace on the Posture and Muscle Activity of Healthy University Students during Prolonged Typing-A Randomized Controlled Cross-Over Trial.

Laptop use appears to contribute to poor working postures and neck pain among university students. Postural braces have the potential to improve upper back/neck posture and therefore might have a role as an ergonomic aid for this population. Therefore, the purpose of this study was to assess the short-term effects of scapular bracing on pain, fatigue, cervicothoracic posture, and the activity of the neck and upper-back muscles in healthy college students. A randomized controlled crossover trial was conducted to evaluate the self-reported pain and fatigue, the amplitude and median frequency of surface electromyography in neck extensors, upper trapezius, and lower trapezius, as well as the neck and shoulder sagittal alignment (measured by inertial sensors and digital photographs) during a 30-min typing task in a sample of young, healthy university students with or without a scapular brace. The brace condition resulted in significantly smaller levels of bilateral trapezius muscle activity (p < 0.01). Rounded shoulder posture was slightly better in the brace condition, but these differences were not significant (p > 0.05). There were no significant immediate differences in pain or fatigue scores, neck alignment, or the electromyographic activity of the other muscles tested between brace and non-brace conditions (all p > 0.05). However, bracing appears to immediately reduce the electromyographic activity of the lower trapezius muscles (p < 0.05). These findings shed some light on the possible advantages of scapular bracing for enhancing laptop ergonomics in this group of individuals. Future studies are warranted to evaluate the effects of different types of braces, the importance of matching the brace to the user, and the short- and long-term effects of brace use on computer posture and muscle activity.

A Hybrid Anchoring Technology Composed of Reinforced Flexible Shells for a Knee Unloading Exosuit.

Soft robotic wearables have emerged as an ergonomic alternative to rigid robotic wearables, commonly utilizing tension-based actuation systems. However, their soft structure's natural tendency to buckle limits their use for compression bearing applications. This study presents reinforced flexible shell (RFS) anchoring, a compliant, low-profile, ergonomic wearable platform capable of high compression resistance. RFS anchors are fabricated with soft and semirigid materials that typically buckle under compressive loads. Buckling is overcome using the wearer's leg as a support structure, reinforcing the shells with straps, and minimizing the space between the shells and the wearer's skin-enabling force transmission orders of magnitude larger. RFS anchoring performance was evaluated comparatively by examining the shift-deformation profiles of three identically designed braces fabricated with different materials: rigid, strapped RFS, and unstrapped RFS. The unstrapped RFS severely deformed before 200 N of force could be applied. The strapped RFS successfully supported 200 N of force and exhibited a nearly identical transient shift-deformation profile with the rigid brace condition. RFS anchoring technology was applied to a compression-resistant hybrid exosuit, Exo-Unloader, for knee osteoarthritis. Exo-Unloader utilizes a tendon-driven linear sliding actuation system that unloads the medial and lateral compartments of the knee. Exo-Unloader can deliver 200 N of unloading force without deforming, as indicted by its similar transient shift-deformation profile with a rigid unloader baseline. Although rigid braces effectively withstand and transmit high compressive loads, they lack compliance; RFS anchoring technology expands the application of soft and flexible materials to compression-based wearable assistive systems.

Tricompartment offloader knee brace reduces sagittal plane knee moments, quadriceps muscle activity, and pain during chair rise and lower in individuals with knee osteoarthritis

The Levitation tricompartment offloader (TCO) knee brace provides an assistive knee extension moment with the goal of unloading all three compartments of the knee and reducing pain for individuals with multicompartment knee osteoarthritis (OA). This study aimed to determine the effect of the TCO brace on sagittal plane knee moments, quadriceps muscle activity, and pain in individuals with multicompartment knee OA. Lower limb kinematics, kinetics, and electromyography data were collected during a chair rise and lower to determine differences between bracing conditions. TCO brace use significantly decreased the peak net knee external flexion moment in high power mode, providing extension assistance during chair rise [p<0.001; mean difference (MD) (98.75% CI) -0.8 (-1.0, -0.6)%BWxH] and bodyweight support during chair lower [p<0.001; -1.1 (-1.6, -0.7)%BWxH]. Quadriceps activation intensity was significantly reduced with brace use by up to 67% for the vastus medialis [Z = -2.55, p = 0.008] and up to 39% for the vastus lateralis [Z = -2.67, p = 0.004]. Participants reported significantly reduced knee pain with the TCO brace worn in high power mode compared to the no brace condition [p = 0.014; MD (97.5% CI) -18.8 (-32.22, -2.34) mm]. These results support the intended mechanism of joint unloading via extension assistance with the TCO brace. The observed biomechanical changes were accompanied by immediate reductions in user reported pain levels, and support the use of the TCO for conservative management to reduce knee pain in patients with multicompartment knee OA.

Effect of base-plate types on system behaviour in down-aisle pallet rack systems

In rack systems, due to operational necessities, bracing of the system is limited in down-aisle direction. In addition, generally thin-walled components with single symmetry axis are used. Therefore, eccentric conditions may occur in the structure, which might affect system stability. There are studies in the literature about the stability aspect of these systems. In terms of stability, use of bracings and support conditions are prominent in rack systems. In this paper, effect of different base-plate types on system behaviour and energy dissipation capacity for low-rise rack systems with different bracing conditions was investigated. In this context, tests and numerical analyses were performed. Numerical models are validated with experimental test. In the test, static pushover has been performed for three two-storey full scaled models with different bracing conditions. For numerical analysis, the static pushover test is performed with the addition of base-plate type changes. In numerical analysis, three types of base-plates are employed with three bracing cases. In this context, it was detected that bracings in the system provide stiffness to the system, however in single-modular rack systems such as the subject of our study, the external bracings cause torsional effects. Therefore, beneficial effect of the bracings can not be utilised efficiently. However, it was also detected that as the rotational stiffness of the base supports increase, torsional effects are restricted. Therefore, it can be suggested that in low-rise, single modular rack systems, use of base-plates with higher stiffness value may provide better system stability as well as more economic solutions.