Stance Width Research Articles

Lower limb joint loading in patients with unilateral hip osteoarthritis during bipedal stance and the effect of total hip replacement.

Osteoarthritis of the hip is a common condition that affects older adults. Total hip replacement is the end-stage treatment to relief pain and improve joint function. Little is known about the mechanical load distribution during the activity of bipedal stance, which is an important daily activity for older adults who need to rest more frequently. This study investigated the distribution of the hip and knee joint moments during bipedal stance in patients with unilateral hip osteoarthritis and how the distribution changed 1year after total hip replacement. Kinematic and kinetic data from bipedal stance were recorded. External hip and knee adduction moments were calculated and load distribution over both limbs was calculated using the symmetry angle. Preoperatively, the non-affected limb carried 10% more body weight than the affected limb when standing on two legs. Moreover, the mean external hip and knee adduction moments of the non-affected limb were increased compared to the affected limb. At follow-up no significant differences were observed between the patients' limbs. Preoperative and postoperative changes in hip adduction moment were mainly explained by the combination of the vertical ground reaction force and the hip adduction angle. Stance width also explained changes in the hip and knee adduction moments of the affected leg. Furthermore, as with walking, bipedal standing also showed an asymmetric mechanical load distribution in patients with unilateral hip osteoarthritis. Overall, the findings suggest the need for preventive therapy concepts that focus not only on walking but also on optimizing stance towards a balanced load distribution of both legs.

EFFECT OF HIGH TIBIAL OSTEOTOMY ON ANKLE AND SUBTALAR JOINT ALIGNMENT

This study aimed to examine the effect of high tibial osteotomy (HTO) on the ankle and subtalar joints via analysis of static radiographic alignment. We hypothesised that surgical alteration of the alignment of the proximal tibia would result in compensatory distal changes.35 patients recruited as part of the wider Biomechanics and Bioengineering Centre Versus Arthritis HTO study between 2011 and 2018 had pre- and postoperative full-length weightbearing radiographs taken of their lower limbs. In addition to standard alignment measures of the limb and knee (mechanical tibiofemoral angle, Mikulicz point, medial proximal tibial angle), additional measures were taken of the ankle/subtalar joints (lateral distal tibial angle, ground-talus angle, joint line convergence angle of the ankle) as well as a novel measure of stance width. Results were compared using a paired T-test and Pearson's correlation coefficient.Following HTO, there was a significant (5.4°) change in subtalar alignment. Ground-talus angle appeared related both to the level of malalignment preoperatively and the magnitude of the alignment change caused by the HTO surgery; suggesting subtalar positioning as a key adaptive mechanism. In addition to compensatory changes within the subtalar joints, the patients on average had a 31% wider stance following HTO. These two mechanisms do not appear to be correlated but the morphology of the tibial plafond may influence which compensatory mechanisms are employed by different subgroups of HTO patients.These findings are of vital importance in clinical practice both to anticipate potential changes to the ankle and subtalar joints following HTO but it could also open up wider indications for HTO in the treatment of ankle malalignment and osteoarthritis.

Glb1 knockout mouse model shares natural history with type II GM1 gangliosidosis patients.

GM1 gangliosidosis is a rare lysosomal storage disorder affecting multiple organ systems, primarily the central nervous system, and is caused by functional deficiency of β-galactosidase (GLB1). Using CRISPR/Cas9 genome editing, we generated a mouse model to evaluate characteristics of the disease in comparison to GM1 gangliosidosis patients. Our Glb1-/- mice contain small deletions in exons 2 and 6, producing a null allele. Longevity is approximately 50 weeks and studies demonstrated that female Glb1-/- mice die six weeks earlier than male Glb1-/- mice. Gait analyses showed progressive abnormalities including abnormal foot placement, decreased stride length and increased stance width, comparable with what is observed in type II GM1 gangliosidosis patients. Furthermore, Glb1-/- mice show loss of motor skills by 20 weeks assessed by adhesive dot, hanging wire, and inverted grid tests, and deterioration of motor coordination by 32 weeks of age when evaluated by rotarod testing. Brain MRI showed progressive cerebellar atrophy in Glb1-/- mice as seen in some patients. In addition, Glb1-/- mice also show significantly increased levels of a novel pentasaccharide biomarker in urine and plasma which we also observed in GM1 gangliosidosis patients. Glb1-/- mice also exhibit accumulation of glycosphingolipids in the brain with increases in GM1 and GA1 beginning by 8 weeks. Surprisingly, despite being a null variant, this Glb1-/- mouse most closely models the less severe type II disease and will guide the development of new therapies for patients with the disorder.

Evaluation of Gait Development Trajectory in Mice

Background/Objective: Movement and walking are huge facets in how we go about our lives and experience the world. Gait is compromised in numerous conditions, from injury and chronic pain to neurological conditions and arthritis. Movement biomechanics have therefore been studied extensively in humans for decades. Although animal models are often used to examine the progression of various health conditions, translational gait research in animal models are less complete, and there is limited information on gait changes as mice grow.
 Methods: We recorded video segments of wild-type C57Bl/6J mice during skeletal growth (5 weeks to 16 weeks) walking (n = 4 Female, n = 2 Male) at 20 cm/s on the DigiGait system, a transparent treadmill equipped with a high-speed camera. Videos captured a ventral view of the mouse and were processed using DigiGait Analysis software, which uses local thresholding and position-finding algorithms to examine paw placement on the treadmill belt. Manual adjustments were made to eliminate artifacts and confirm heel-strike and toe-off times. After these corrections, the software returns stride parameters that were compared between sexes.
 Results: Over 30 gait metrics, including stride length, frequency, stance/swing times, and stance width, were calculated for all four limbs per animal for several time points. Stride length increased from 4.5 ± .5 cm at week 5 to 5.0 ± .8 cm at week 16, and frequency decreased from 4.6 ± .6 to 4.2 ± .6 steps per second. No notable changes in stance width, symmetry, or stance/swing ratio were identified.
 Conclusion and Potential Impact: Future directions for this research include conducting a principal component analysis to investigate the variability within the gait data. Identifying trends in gait parameters will help create a more complete picture of gait maturation. Establishing this baseline data allows for its comparison against treatment groups and the potentially meaningful investigation of translatable therapeutics and interventions.

Staff Low Back Injury Risk During Assisted Falls Virtual Reality Simulations.

Assisted falls occur when staff try to minimize the impact of falls by slowing a patient's descent. Assisting a patient fall may decrease patient injury risk, but biomechanical risk of injury to staff has not been evaluated. Assisted falls virtual reality (VR) simulations were conducted to examine staff low back injury risk during common assisted falls scenarios. VR simulations of a toilet to wheelchair transfer were developed with a male patient avatar for three assisted falls scenarios: standing up from toilet, sitting down on wheelchair, and ambulation. Patient avatar weight was modified to reflect normal, underweight, and overweight adult patients. The average spinal compression force at L5/S1 was calculated for each participant with five trials per three scenarios while utilizing physical ergonomic techniques and compared to the safe spinal compression limit of 3,400 Newtons (N). Six staff participants completed 90 VR simulations in total. The average calculated spinal compression force ranged from 7,132 N to 27,901 N. All participant trials exceeded the safe spinal compression limit of 3,400 N for every assisted falls scenario and avatar weight despite application of ergonomic techniques including wide stance, knees bent, and backs straight. Staff are at risk for low back injury if they assist falls regardless of the adult patient weight and application of ergonomic techniques. Safer alternatives like the implementation of mobility screening tools and safe patient handling and mobility technology are needed to help prevent assisted falls to decrease injury risk to both patients and staff.

Gait analysis using physical examination and digital techniques

Gait examination is an important component of the patient assessment prior to movement therapy. With the advancement of video technology and computer science, digital analysis of gait has become possible. This research aims to physically examine gait and analyze video recordings using dedicated software. A voluntary group of 10 individuals diagnosed with coxarthrosis or gonarthrosis constituted the study group, while the control group comprised 10 individuals without lower limb musculoskeletal disorders. The mean age of the study group was 57 ±4.03 years, and the mean age of the control group was 54.2 ±3.16 years. The research involved conducting physical examinations of gait and recording walking sessions with body markers. The software facilitated the presentation of marker displacements on diagrams in both vertical and horizontal planes. Visual analysis and a two-sample t-test were employed. The physical musculoskeletal examination successfully identified causes of claudication. Significant differences were observed between the two groups across all kinematic gait indicators. The mean stance width in the test group was 17.65 ±3.09 cm, while the control group averaged 8.75 ±1.23 cm (p < 0.001). The walking speed, assessed using a two-sample t-test, also yielded a significant difference (p < 0.001). Key diagrams representing the groups during functional analysis were presented. Visual analysis revealed distinct variations in marker frequency and vertical and horizontal displacements between the groups. The study group exhibited notable deviations in the displacement diagrams on the affected side of the body. The average of the maximum and minimum points on the charts demonstrated a significant difference between the groups in terms of body displacement. The identified differences in gait between the two groups align with the results of the physical examination. The graphical representation of disparities in body displacement between the two halves of the body in the study group indicates the future potential of digital gait analysis for practical applications and monitoring the effectiveness of physiotherapy.

Potential biomechanical risk factors on developing lead knee osteoarthritis in the golf swing

The load on the lead knee joint during a golf swing is greater than that observed during gait. However, current evidence regarding golf swing biomechanics for risks associated with knee osteoarthritis (OA) is limited. Therefore, this study investigated golf swing styles associated with knee adduction and abduction moments, which are considered to be crucial loading regions of the medial and lateral compartments of knee OA, respectively. Thirteen professional male golfers performed five shots using a 5-iron club, and their swings were recorded using a motion capture system with two force platforms for the feet. A regression analysis was performed to calculate the correlation coefficients between the peak knee adduction and abduction moments of the lead leg and varus/valgus angle, toe-out angle, stance width, weight transfer, and shoulder sway. Swinging with a narrower stance width at address (r = − 0.62, p = 0.02) with more weight shift (r = 0.66, p = 0.014) and shoulder sway (r = 0.79, p = 0.001) towards the target during the downswing were associated with a higher peak knee adduction of the lead leg, whereas a greater valgus angle at address (r = 0.60, p = 0.03) was associated with a higher peak knee abduction of the lead leg. Based on these findings, we anticipate future research to support postural changes, particularly a wider stance width and restricted shoulder sway for golfers who are classified to be at high risk of developing medial compartment knee OA, as well as a lower valgus (tibial medial tilt) angle at address for those classified to be at high risk of developing lateral compartment knee OA.

The relationship between the squat technique, anthropometric characteristics and the level of flexibility development in high-class powerlifters

The problem of improving the technical training of powerlifters has been considered in a large number of scientific studies, and in general, technical training as a significantly significant factor is one of the most studied aspects of the training of athletes in the general theory of training. At the same time, most works devoted to various aspects of technical training of powerlifters relate to the equipment division. The study of technical training of athletes in the classic division, which is a relatively young type of powerlifting, remains outside the attention of researchers. The problem of compliance of the technique of competitive exercises with anthropometric features and the level of flexibility development of powerlifters is an important task of modern sports practice. The goal is to identify the relationship between flexibility indicators, anthropometric features and the technique of squats in high- class powerlifters. To solve the set goal, we used the following research methods: analogy, analysis, synthesis, abstraction, induction, extrapolation, generalization of practical experience, pedagogical methods (observation). On the basis of pedagogical observation, it was established that the choice of the style of placement of the barbell on the shoulders and the width of the leg rack during the first competitive exercise is influenced by the anthropometric features of powerlifters and the level of flexibility development. Most elite athletes use a low barbell position on the shoulders when performing barbell squats, indicating that a low barbell position on the shoulders is more effective than a high barbell position. Analysis of the results of the study confirms that the majority of high-end powerlifters use more of the average width of the leg rack when performing squats on the shoulders. The number of athletes who perform squats on their shoulders in a wide stance increases as the nominal weight category increases.

Deep Learning: Predicting Environments From Short-Time Observations of Postural Balance.

This study introduces a deep learning approach to accurately predict challenging mechanical environments that possibly cause decreasing postural stability. Dual-axis robotic platforms were utilized to simulate various environments and collect center-of-pressure data during narrow and wide stance. A convolutional neural network (CNN) was developed to predict environmental conditions given segmented time-series balance data. Different window sizes were examined to investigate its minimal length for reliable prediction. Effectiveness of the presented CNN was additionally compared with that of conventional machine learning models. Its applicability with low sampled data or more natural stance data was then evaluated. The CNN achieved above 94.5% in the overall prediction accuracy even with 2.5-second length postural sway data, which cannot be achieved by traditional machine learning (ps < 0.05). Increasing data length beyond 2.5 seconds slightly improved the accuracy of CNN but substantially increased training time (60% longer). Importantly, results from averaged normalized confusion matrices revealed that CNN is much more capable of differentiating the mid-level environmental condition. Deep learning could also produce comparable performance in predicting environments even with much lower sampled data or with standing posture changed. CNN removed the burden of feature preparation and accurately predicted environments when dealing with short-length data. It also indicated potentials to real life applications. This study contributes to the advancement of wearable devices and human interactive robots (e.g., exoskeletons and prostheses) by predicting environmental contexts and preventing potential falls.

The Effects of Functional Ankle Taping on Postural Stability in Elite Judo Players

The purpose of this study was to investigate the effect of ankle taping intervention on postural stability in elite Judo players. A total of twenty-two elite Judo players participated in this study. For biomechanical evaluation of postural stability, all participants performed postural standing tasks including narrow, normal, and wide stance conditions with both taping and non-taping conditions, respectively. Ground reaction forces and the center of pressure (COP) were obtained from the force plate. COP data for 30-s duration were analyzed to assess postural stability by measuring 95% confidence ellipse sway area (COPSWAY), COP velocity (COPVEL), and approximate entropy (ApEn). Significant differences were found in COPSWAY (p = 0.025) and COPVEL (p = 0.041) in the narrow stance, but no differences in normal and wide stances were observed between taping and non-taping conditions. For ApEn in the anteroposterior (AP) direction, significant differences were identified in normal (p = 0.026) and wide (p = 0.014) stances, but in the mediolateral direction there were no significant differences in all stances between taping and non-taping conditions. This study suggests that ankle taping that is purported to increase ankle stability may ironically negatively affect posture maintenance in Judo players. Our study suggests that the purpose of ankle taping should be reconsidered and associated individual objective data should be first analyzed before tape application.

Kinematic adaptations to restricting spine motion during symmetrical lifting

When lifting an object from the ground a person has many possible whole-body movement solutions to accomplish the task. It is unclear why lifters use most of their available lumbar spine flexion range-of-motion despite many ergonomic guidelines advising against doing so. Experimentally restricting spine motion and observing compensatory movement strategies is one approach to address this knowledge gap. A kinematic analysis was performed on 16 participants who completed symmetrical lifting tasks with and without wearing a spine motion-restricting device. Sagittal trunk, lumbar spine, and lower extremity kinematics, along with stance width and foot orientation in the transverse plane were evaluated between restricted and unrestricted lifting conditions. Restricting spine motion required greater ankle dorsiflexion (p < 0.001), knee flexion (p < 0.001), and hip flexion (p < 0.001) motion in comparison to unrestricted lifting. Motion was reallocated such that hip flexion showed the largest increase in restricted lifting, followed by ankle dorsiflexion, then knee flexion compared to unrestricted lifting. Trunk inclination decreased (i.e., more upright) in restricted compared to unrestricted lifting (p < 0.001). Neither stance width (p = 0.163) nor foot orientation (p = 0.228) were affected by restricting spine motion. These adaptive movements observed indicate lower extremity joint motion must be available and controlled to minimize lumbar spine flexion during lifting.

Design and Motion Planning for a Reconfigurable Robotic Base

A robotic platform for mobile manipulation needs to satisfy two contradicting requirements for many real-world applications: A compact base is required to navigate through cluttered indoor environments, while the support needs to be large enough to prevent tumbling or tip over, especially during fast manipulation operations with heavy payloads or forceful interaction with the environment. This paper proposes a novel robot design that fulfills both requirements through a versatile footprint. It can reconfigure its footprint to a narrow configuration when navigating through tight spaces and to a wide stance when manipulating heavy objects. Furthermore, its triangular configuration allows for high-precision tasks on uneven ground by preventing support switches. A model predictive control strategy is presented that unifies planning and control for simultaneous navigation, reconfiguration, and manipulation. It converts task-space goals into whole-body motion plans for the new robot. The proposed design has been tested extensively with a hardware prototype. The footprint reconfiguration allows to almost completely remove manipulation-induced vibrations. The control strategy proves effective in both lab experiment and during a real-world construction task.

Computational evaluation of psoas muscle influence on walking function following internal hemipelvectomy with reconstruction.

An emerging option for internal hemipelvectomy surgery is custom prosthesis reconstruction. This option typically recapitulates the resected pelvic bony anatomy with the goal of maximizing post-surgery walking function while minimizing recovery time. However, the current custom prosthesis design process does not account for the patient’s post-surgery prosthesis and bone loading patterns, nor can it predict how different surgical or rehabilitation decisions (e.g., retention or removal of the psoas muscle, strengthening the psoas) will affect prosthesis durability and post-surgery walking function. These factors may contribute to the high observed failure rate for custom pelvic prostheses, discouraging orthopedic oncologists from pursuing this valuable treatment option. One possibility for addressing this problem is to simulate the complex interaction between surgical and rehabilitation decisions, post-surgery walking function, and custom pelvic prosthesis design using patient-specific neuromusculoskeletal models. As a first step toward developing this capability, this study used a personalized neuromusculoskeletal model and direct collocation optimal control to predict the impact of ipsilateral psoas muscle strength on walking function following internal hemipelvectomy with custom prosthesis reconstruction. The influence of the psoas muscle was targeted since retention of this important muscle can be surgically demanding for certain tumors, requiring additional time in the operating room. The post-surgery walking predictions emulated the most common surgical scenario encountered at MD Anderson Cancer Center in Houston. Simulated post-surgery psoas strengths included 0% (removed), 50% (weakened), 100% (maintained), and 150% (strengthened) of the pre-surgery value. However, only the 100% and 150% cases successfully converged to a complete gait cycle. When post-surgery psoas strength was maintained, clinical gait features were predicted, including increased stance width, decreased stride length, and increased lumbar bending towards the operated side. Furthermore, when post-surgery psoas strength was increased, stance width and stride length returned to pre-surgery values. These results suggest that retention and strengthening of the psoas muscle on the operated side may be important for maximizing post-surgery walking function. If future studies can validate this computational approach using post-surgery experimental walking data, the approach may eventually influence surgical, rehabilitation, and custom prosthesis design decisions to meet the unique clinical needs of pelvic sarcoma patients.

Functional Gait Assessment Using Manual, Semi-Automated and Deep Learning Approaches Following Standardized Models of Peripheral Nerve Injury in Mice.

Objective: To develop a standardized model of stretch–crush sciatic nerve injury in mice, and to compare outcomes of crush and novel stretch–crush injuries using standard manual gait and sensory assays, and compare them to both semi-automated as well as deep-learning gait analysis methods. Methods: Initial studies in C57/Bl6 mice were used to develop crush and stretch–crush injury models followed by histologic analysis. In total, 12 eight-week-old 129S6/SvEvTac mice were used in a six-week behavioural study. Behavioral assessments using the von Frey monofilament test and gait analysis recorded on a DigiGait platform and analyzed through both Visual Gait Lab (VGL) deep learning and standardized sciatic functional index (SFI) measurements were evaluated weekly. At the termination of the study, neurophysiological nerve conduction velocities were recorded, calf muscle weight ratios measured and histological analyses performed. Results: Histological evidence confirmed more severe histomorphological injury in the stretch–crush injured group compared to the crush-only injured group at one week post-injury. Von Frey monofilament paw withdrawal was significant for both groups at week one compared to baseline (p < 0.05), but not between groups with return to baseline at week five. SFI showed hindered gait at week one and two for both groups, compared to baseline (p < 0.0001), with return to baseline at week five. Hind stance width (HSW) showed similar trends as von Frey monofilament test as well as SFI measurements, yet hind paw angle (HPA) peaked at week two. Nerve conduction velocity (NCV), measured six weeks post-injury, at the termination of the study, did not show any significant difference between the two groups; yet, calf muscle weight measurements were significantly different between the two, with the stretch–crush group demonstrating a lower (poorer) weight ratio relative to uninjured contralateral legs (p < 0.05). Conclusion: Stretch–crush injury achieved a more reproducible and constant injury compared to crush-only injuries, with at least a Sunderland grade 3 injury (perineurial interruption) in histological samples one week post-injury in the former. However, serial behavioral outcomes were comparable between the two crush groups, with similar kinetics of recovery by von Frey testing, SFI and certain VGL parameters, the latter reported for the first time in rodent peripheral nerve injury. Semi-automated and deep learning-based approaches for gait analysis are promising, but require further validation for evaluation in murine hind-limb nerve injuries.

A Multi-Experiment Investigation of the Effects Stance Width on the Biomechanics of the Barbell Squat.

This two-experiment study aimed to explore habitual and manipulated stance widths on squat biomechanics. In experiment one, 70 lifters completed back squats at 70%, 1 repetition maximum (1RM), and were split into groups (NARROW < 1.06 * greater trochanter width (GTW), MID 1.06–1.18 * GTW and WIDE > 1.37 * GTW) according to their self-selected stance width. In experiment two, 20 lifters performed squats at 70%, 1RM, in three conditions (NARROW, MID and WIDE, 1.0, 1.25 and 1.5 * GTW). The three-dimensional kinematics were measured using a motion capture system, ground reaction forces (GRF) using a force platform, and the muscle forces using musculoskeletal modelling. In experiment two, the peak power was significantly greater in the NARROW condition, whereas both experiments showed the medial GRF impulse was significantly greater in the WIDE stance. Experiment two showed the NARROW condition significantly increased the quadriceps forces, whereas both experiments showed that the WIDE stance width significantly enhanced the posterior-chain muscle forces. The NARROW condition may improve the high mechanical power movement performance and promote the quadriceps muscle development. Greater stance widths may improve sprint and rapid change-of-direction performance and promote posterior-chain muscle hypertrophy. Whilst it appears that there is not an optimal stance width, these observations can be utilized by strength and conditioning practitioners seeking to maximize training adaptations.

Behavioral Study of Parkinson's Disease Rats Model with DigiGait&amp;lt;sup&amp;gt;TM&amp;lt;/sup&amp;gt; Imaging System

<bold>Objective</bold> To detect the feasibility of DigiGait^TM Imaging System in evaluating gait changes in rats model with Parkinson's disease (PD). <bold>Methods</bold> A total of 24 clean male SD rats were randomly divided into normal group, sham operation group and model group, with eight rats in each group. In the model group, 6-Hydroxydopamine (6-OHDA) was injected into the brain with unilateral 2-point method to establish PD rats model. The sham operation group was injected with 0.2% ascorbic acid solution with the same method, and the normal group did not receive any surgical treatment. After successful preparation of the model, DigiGait^TM Imaging System was used to analyze temporal subcomponent (swing duration, braking duration, stance duration, stance factor), spatial subcomponent (stride frequency, stride length, stance width, gait symmetry, paw overlap distance, paw placement positioning) and postural subcomponent (paw angle, step angle, paw area). <bold>Results</bold> 1) Temporal subcomponent: compared with the normal group, the swing duration, braking duration and stance duration of left front paw, left hind paw and right front paw in the model group were significantly prolonged (<italic>P</italic>&lt;0.05), and the braking duration and swing duration of right hind paw in the model group were significantly prolonged (<italic>P</italic>&lt;0.05). Compared with the sham operation group, the swing duration, braking duration and stance duration of left front paw, left hind paw and right front paw in the model group were significantly prolonged (<italic>P</italic>&lt;0.05), and the braking duration of right hind paw in the model group was significantly prolonged (<italic>P</italic>&lt;0.05). 2) Spatial subcomponent: compared with the normal group and the sham operation group, the front and hind limb stance width of the model group significantly increased (<italic>P</italic>&lt;0.05), step frequency of four paws, stride length of left paws and paw placement positioning and gait symmetry in the model group significantly decreased (<italic>P</italic>&lt;0.05). But stride length of right paws and overlap distance of left and right paws in the model group had no significant changes (<italic>P</italic>&gt;0.05). 3) Postural subcomponent: compared with the normal group and the sham operation group, the contact area of left front paw, left hind paw and right hind paw with running belt in the model group significantly decreased (<italic>P</italic>&lt;0.05), there was no significant difference in paw area, paw angle and gait angle between the right front paw and the running belt (<italic>P</italic>&gt;0.05). <bold>Conclusion</bold> DigiGait^TM Imaging System can objectively evaluate walking, balance and coordination functions of PD rats, which has the potential to be widely applied in PD related basic research.

Peripheral Nerve Regeneration with Acellular Nerve Allografts Seeded with Amniotic Fluid-Derived Stem Cells.

Introduction Tissue engineering strategies have attempted to mimic regenerating axons' environment by adding supportive types of cells other than Schwann cell to the nerve allograft. We hypothesized that allografts can be seeded with amniotic fluid-derived stem cells (AFS) to promote nerve regeneration. Methods ANAs with AFS cells for long-gap nerve repairs were studied using a rat model. A sciatic nerve injury was created and repaired immediately with a rat acellular nerve allograft (ANA) construct alone, an ANA construct seeded with AFS cells, or with an autograft. Walking track analysis and electrophysiology were performed to document the return of motor control at 4 months post injury. Axon morphology on the nerve segments was assessed. Results In vivo gait analysis showed that the ANA plus AFS cell group had significantly advanced recoveries in overlap distance, paw angle degree, paw drag, stance width, axis distance, and sciatic function index (SFI) compared with ANA alone. The ANA plus AFS cell group also demonstrated greater gastrocnemius compound muscle action potential (CMAP) ratio, sciatic axon diameter, fiber diameter, myelin thickness, G ratio (average axonal diameter (AD)/fiber diameter (FD)), and neuromuscular junction (NMJ) numbers compared to ANA. Discussion. The allograft plus AFS cell group demonstrated significantly improved functional and histological outcomes compared to allograft group alone, showing no significant difference of the nerve regeneration from the autograft group. Thus, AFS cells may be a suitable cell source to replace Schwann cells to support and accelerate peripheral nerve regeneration following large-gap nerve injury.

Relationship Between the Kinematical Factors and The Ball Velocity of the Penalty Corner Drag-Flick in Field Hockey

The aim of the study was to analyze the relationship of the kinematical factors with the ball velocity of the drag flick performance of the national elite players in field hockey. To attain this purpose, 64 drag flicks of sixteen players were recorded and analyzed through the VICON motion capture system and MATLAB software. The descriptive statistics and Spear man correlation were computed for statistical analysis. The mean ball velocity of the drag-flicks of the female and male players were 21.31±3.53 m/sand 15.10±4.02 m/s, respectively. The ball dragging length, ball dragging velocity, stance width, left-knee angle and left elbow angle had a significant correlation with the ball velocity. The subjects maximize dragging length,dragging velocity and stance width while minimizing their left-right knee angles for high velocity. Players and coaches should emphasize ball dragging length, dragging velocity and stance width to improve the drag flick performance.

Association Between Landing Error Scoring System (LESS) Items and the Incidence Rate of Lower Extremity Stress Fracture.

Background:Lower extremity stress fracture injuries are a major cause of morbidity in physically active populations. The ability to screen for modifiable risk factors associated with injury is critical in developing injury-prevention programs.Purpose:To determine if baseline Landing Error Scoring System (LESS) scores are associated with the incidence rate of lower extremity stress fracture.Study Design:Cohort study; Level of evidence, 2.Methods:A total of 1772 participants with no history of lower extremity stress fracture were included. At preinjury baseline, the authors conducted a lower extremity movement assessment during a jump-landing task using the LESS. Incident lower extremity stress fractures were identified during a 4-year follow-up period. Potential incident cases were reviewed by 2 sports medicine fellowship–trained orthopaedic surgeons blinded to baseline LESS data. Univariate and multivariable Poisson regression models were used to estimate the association between baseline total LESS scores, individual LESS items, and the incidence rate ratio (IRR) of lower extremity stress fracture.Results:A total of 94 incident lower extremity stress fractures were documented, for a 5.3% (95% CI, 4.3%-6.5%) cumulative incidence. The overall LESS score was associated with the incidence rate of lower extremity stress fracture. For every additional movement error documented at baseline, there was a 15% increase in the incidence rate of lower extremity stress fracture (IRR, 1.15 [95% CI, 1.02-1.31]; P = .025). In univariate analyses, ankle flexion, stance width, asymmetrical landing, and trunk flexion at initial contact, in addition to overall impression, were associated with the incidence rate of stress fracture. After controlling for sex and year of entry into the study cohort, participants who consistently landed flat-footed or heel-to-toe were 2.33 times (95% CI, 1.36-3.97; P = .002) more likely to sustain a lower extremity stress fracture. Similarly, participants who consistently demonstrated asymmetric landing at initial contact were 2.53 times (95% CI, 1.34-4.74; P = .004) more likely to sustain a stress fracture.Conclusion:Components of the LESS may be associated with increased lower extremity stress fracture risk and may be helpful in efficiently assessing high-risk lower extremity biomechanics in large groups.

Kinetic Gait Parameters in Unilateral Lower Limb Amputations and Normal Gait in Able-Bodied: Reference Values for Clinical Application.

Unilateral lower limb amputations usually present with asymmetric interlimb gait patterns, in the long term leading to secondary physical conditions and carrying the risk of low physical activity and impairment of general health. To assess prosthetic fittings and rehabilitation measures, reference values for asymmetries as well as the most significant gait parameters are required. Kinetic gait data of 865 patients with unilateral lower limb amputations (hip and knee disarticulations, transfemoral, transtibial and foot amputations) and 216 able-bodied participants were quantitatively assessed by instrumented gait analyses. Characteristic spatiotemporal (stance time, walking speed, step length and width) and ground reaction force parameters (weight-acceptance and push-off peak) were contrasted to normal gait. All spatiotemporal and ground reaction force parameters differed significantly from normal gait with the largest differences in transfemoral amputations. These also differed between amputation levels and showed age-dependencies. The stance time and push-off peak difference were identified as the most discriminative parameters with the highest diagnostic specificity and sensitivity. The present results mark the first step to establishing universal reference values for gait parameters by means of which the quality and suitability of a prosthetic fitting and the rehabilitation progress can be assessed, and are generalizable for all adults with unilateral lower limb amputations in terms of level walking.