Mediolateral Research Articles

Do timed up and go and five times sit to stand test outcomes correlate with trunk stability? A pilot-study

BACKGROUND: Five Times Sit to Stand (FTSS) and Timed Up and Go (TUG) are clinical tests in which performance is evaluated through completion time, which can be thought to reflect dynamic balance. Completion time in these tests, however, can be affected not only by balance stability but also by other important components, such as legs’ muscular strength and velocity. AIM: This investigation aimed to evaluate the correlation of completion times in these clinical tests and mediolateral (ML) balance stability measured through lower trunk accelerometry in older individuals. METHOD: Fifteen volunteers were evaluated, aged 60-86 years (M = 69.56±5.89 years). For TUG, we evaluated the conventional version of the test (TUGC), in addition to a dual task (TUGDT) and a new overline (TUGOL) version featured by increased balance demand. Balance stability during test performance was measured through ML accelerations of the lower trunk. RESULTS: The results indicated negative time-acceleration correlations for TUGC (rp = -.71, rp2 =.50, p <.01) and TUGDT (rp = -.77, rp2 =.59, p <.01) and a positive correlation for FTSS (rp =.73, rp2 =.53, p <.01). The TUGOL test failed to show significant time-acceleration correlations. CONCLUSION: Our results suggest that completion time in the FTSS test importantly reflects dynamic balance stability in older individuals. On the other hand, ML trunk acceleration when performing TUG seems to be more related to movement speed than body balance. Our results suggest that completion time can be considered a predictor of dynamic balance in the FTSS test.

The impact of coracoid morphometry on internal rotation outcome in patients with cuff tear arthropathy treated with reverse shoulder arthroplasty

BackgroundFunctional internal rotation (fIR) motion remains a concern after reverse shoulder arthroplasty (RSA). The extreme variability of the coracoid morphometry together with the gain in tension of the conjoint tendon could impact internal rotation (IR) after RSA. Our aim was to evaluate the relationship between postoperative IR outcome and coracoid morphometry, evaluated as anteroposterior (AP) and mediolateral (ML) glenocoracoid distances in a 3-dimensional preoperative computed tomography scans, in a consecutive series of patients undergoing the same RSA implant. Materials and methodsA retrospective analysis of a prospectively collected series of 40 patients (18 male, 22 female; mean age (standard deviation [SD]), 73.4 years [4.1]) submitted to RSA for cuff tear arthropathy was performed. fIR function was measured as the highest midline segment of the back that can be reached and converted into 5 range segments of motion. Participants were divided into 2 groups according to the fIR (group A, ≤6; group B, >6). Passive IR was also measured. The AP and ML glenocoracoid distances were measured, in millimeters, on the preoperative 3-dimensional computed tomography scans. Statistics were performed. ResultsThe mean follow-up was 29 months (range, 24-39). The mean score for fIR was 6.45 (SD: 1.81) while the mean score for passive IR was 6.84 (SD: 1.75). No difference was found between fIR and passive IR (P = .328). No statistical difference was found between fIR and glenosphere size (P = .562) and fIR and size of the liner (P = .429). Significant statistical correlations have been found between AP and ML coracoid distances and the two groups (AP in group A: 28.50 and B: 31.265, P = .034; ML in group A: 23.053 and B: 14.27, P < .001). ConclusionsOur study demonstrated that coracoid morphometry, evaluated as glenocoracoid distance, significantly impact IR outcomes in a 145° neck shaft angle RSA; in particular, a high ML glenocoracoid distance (>23 mm) was found to be determinant. This anatomical parameter should be considered in the preoperative planning of RSA and additional surgical strategies addressed in order to gain satisfactory fIR.

Investigation of Static Balance Differences between Adolescents with Idiopathic Scoliosis and Healthy Age-matched Adolescents: A Cross-sectional Study

Background: The aim of this study was to compare postural control between Adolescents with Idiopathic Scoliosis (AIS) and healthy adolescents. Methods: In this cross-sectional study, 20 AIS adolescents with a right thoracic curvature between 10 and 45 degrees and 20 healthy adolescents were matched to compare postural control. Postural control assessments included Center of Pressure (COP) range and COP velocity in the Anteroposterior (AP) and Mediolateral (ML) directions, and the COP sway area in the standing position with opened eyes and closed eyes by the force plate. Results: This study showed that the postural control variables in AIS adolescents and healthy adolescents in terms of COP range, COP velocity, and COP sway area in standing positions with open and closed eyes were significantly different with those of AIS adolescents being worse than those of healthy adolescents (all p&lt;0.001). The interaction between Group and Condition (eyes open and eyes closed) was not significant for all variables (all p&gt;0.05). Conclusion: Differences in the postural control measures indicate postural instability in adolescents with AIS compared to healthy adolescents.

Subjective Vs Objective Clinical Tools for Balance Assessment in Healthy Population

Background: The clinicians prefer subjective tools for balance assessment that are easily available and multiple researches have proved them reliable and valid for balance assessment. The force plate measures do the same postural analysis as we expect the other subjective tools to perform. Objectives: To determine the correlation between subjective and objective standard tools of balance assessment in healthy population Material and method: It was cross sectional observational study carried out at National institute of rehabilitation medicine (NIRM) Islamabad and Riphah international university Islamabad from January 2019 to June 2019.The sample size was calculated by using G power analysis graph, came out to be 64 for every age group. In this study non-probability purposive sampling technique was used. The inclusion criterion includes healthy individuals with 18-70 years of age (young (18-25 years), adult (25 -50 years), elderly (50-70 years) and both genders. Tools used in this research were BBS (Berg Balance Scale), POMA (The Performance-Oriented Mobility), TUG (Time Up and Go test), FRT (Functional Reach Test), Romberg test, SLS (Single Leg Stance), YBT (Y Balance Test) and Force plate. Results: 192 total respondents were divided in equal distribution of 64 in three age groups of elderly, adults and young. In elderly group males were 49and females were 15. In adult group males were 27 while females were 37.In young category total number of males were 27while females were 37. Mean age and SD for elderly, adults and young were 57.3±5.51, 35.4±6.97 and 22.6±1.62 respectively. This study results were affirming the fact that force plate variables has significant correlations with subjective tools of balance. (YBT, r=0.3 and SLS, r=0.8). Conclusion: This study concludes that force plate can replace or validate the subjective tools of balance that we use for different age groups. SLS (Single Leg Stance) is strongly and positively correlates with total AP sway on force plate, and shows strong negative correlation with AP standard deviation. YBT (Y-balance test) can also be validated or replaced for Total ML sway of force plate as it shows moderate correlation. On the other hand POMA, TUG, FRT shows weak and negative correlations with most of the force plate variables. Keywords: BBS (berg balance scale), ML (mediolateral), SD (standard deviation), YBT (Y-balance test)

Evaluation of Static and Dynamic Stability and Its Relationship With Fear of Falling in Patients With Mild to Moderate Knee Osteoarthritis

Objective Knee osteoarthritis is one of the most common musculoskeletal disorders affecting balance. It is also a risk factor for falling in older people. People with a history of falling, whether being injured or not, acquire a fear of potential falling, so they limit their functional activities, leading to decreased mobility, muscle weakness, and increased risk of falling in the future. Evaluating the relationship between balance and fear of falling in these patients can detect the disability mechanisms and falling and also help find more effective therapeutic methods for these patients. Some previous studies evaluated the stability of patients by clinical methods in static situations and related it to fear of falling. However, the walking stability of patients was not assessed by laboratory-based systems in previous studies. Therefore, we aimed to evaluate dynamic (during walking and based on the center of mass sways) and static stability (based on the center of pressure sways) and their relationship with falling risk in patients with knee osteoarthritis. Materials &amp; Methods This is a descriptive cross-sectional study. A group of 15 subjects with mild to moderate knee osteoarthritis with a Mean±SD age of 50±3.22 years and 15 normal subjects with comparable age, height, and weight participated in this study. The subjects’ standing stability was evaluated using a Kistler force plate based on mediolateral (ML) and anteroposterior (AP) displacements of the center of pressure. Also, the dynamic stability of the subjects was evaluated during walking and based on the center of mass-base of support relationship in AP and ML directions. Kinematic data were collected using a motion analysis system with 7 high-speed cameras and a Kistler force plate. To model the body segments, the output of Qualisys track manager software was exported to Visual 3D software. Fear of falling was assessed by the native version of the fall efficacy scale (FES-I). The normal distribution of data was checked by the Shapiro-Wilk test. The independent samples t-test was used to compare the stability of patients and normal subjects. The Pearson correlation coefficient was used to evaluate the relationships between static and dynamic stability parameters and fear of falling in patients with knee osteoarthritis. Results Patients with knee osteoarthritis had less stability during standing and walking than healthy subjects (P&lt;0.05). Moreover, based on the results of this study, there was a linear relationship between the center of body pressure (COP) excursions in the AP direction and the fear of falling scale. Still, it was not significant (r=0.416, P=0.123), and there was no correlation between the other COP parameters with FES (r=0, P&gt;0.05). The correlations between mean center of mass (COM) excursion in AP and ML directions and FES were 0.309 and -0.123, respectively; however, these correlations were also not statistically significant (P&gt;0.05). Conclusion Based on the results of this study, there is no significant relationship between static and dynamic stability of the patients with mild to moderate knee osteoarthritis (based on COP-COM variables) and the fall efficiency scale. So, it seems that to improve these patients’ functional abilities, and the therapists must focus on the other parameters that affect the falling, such as reducing pain, improving proprioception, and enhancing muscle strength. It is suggested that future studies include a more varied age range of elderly people and evaluate all contributing factors in falling of patients with knee osteoarthritis (such as pain, proprioception, vision, and muscle strength) and also evaluate the stability of patients with both laboratory-based and clinical tests.

The effects of proprioceptive weighting changes on posture control in patients with chronic low back pain: a cross-sectional study.

Patients with chronic low back pain (CLBP) exhibit changes in proprioceptive weighting and impaired postural control. This study aimed to investigate proprioceptive weighting changes in patients with CLBP and their influence on posture control. Sixteen patients with CLBP and 16 healthy controls were recruited. All participants completed the joint reposition test sense (JRS) and threshold to detect passive motion test (TTDPM). The absolute errors (AE) of the reposition and perception angles were recorded. Proprioceptive postural control was tested by applying vibrations to the triceps surae or lumbar paravertebral muscles while standing on a stable or unstable force plate. Sway length and sway velocity along the anteroposterior (AP) and mediolateral (ML) directions were assessed. Relative proprioceptive weighting (RPW) was used to evaluate the proprioception reweighting ability. Higher values indicated increased reliance on calf proprioception. There was no significant difference in age, gender, and BMI between subjects with and without CLBP. The AE and motion perception angle in the CLBP group were significantly higher than those in the control group (JRS of 15°: 2.50 (2.50) vs. 1.50 (1.42), JRS of 35°: 3.83 (3.75) vs. 1.67 (2.00), pJRS < 0.01; 1.92 (1.18) vs. 0.68 (0.52), pTTDPM < 0.001). The CLBP group demonstrated a significantly higher RPW value than the healthy controls on an unstable surface (0.58 ± 0.21 vs. 0.41 ± 0.26, p < 0.05). Under the condition of triceps surae vibration, the sway length (pstable < 0.05; punstable < 0.001), AP velocity (pstable < 0.01; punstable < 0.001) and ML velocity (punstable < 0.05) had significant group main effects. Moreover, when the triceps surae vibrated under the unstable surface, the differences during vibration and post vibration in sway length and AP velocity between the groups were significantly higher in the CLBP group than in the healthy group (p < 0.05). However, under the condition of lumbar paravertebral muscle vibration, no significant group main effect was observed. The patients with CLBP exhibited impaired dynamic postural control in response to disturbances, potentially linked to changes in proprioceptive weighting.

Correlation between the Insertion Side of a Transcondylar Screw for the Surgical Management of Humeral Intracondylar Fissures in Dogs and the Incidence of Postoperative Surgical Site Infection.

An increased rate of surgical site infection (SSI) following treatment of canine humeral intracondylar fissure (HIF) with a lateromedially (LM) placed transcondylar screw (TCS) compared with a mediolateral (ML) TCS has been previously postulated. We hypothesized that the direction of insertion of the TCS would not affect the incidence of postoperative SSI. It was single-centre retrospective study. Dogs with HIF confirmed by computerized tomography, treated by TCS placement (between 2008 and 2019) and with a minimum follow-up of 12 weeks, were included. The following data were recorded: signalment, presenting clinical signs, direction of placement and size of the utilized TCS, surgical and anaesthetic times, concurrent surgical procedures, presence of concomitant elbow pathology, perioperative and postoperative antibiotic usage and postoperative complications. Recorded data were analysed with a multinomial logistic regression model with a p-value less than or equal to 0.05. Thirty-five dogs (46 elbows) met the inclusion criteria. Median clinical follow-up interval was 52 weeks. Seven of thirty-one elbows with a ML TCS, and 4/15 elbows with a LM TCS developed SSI. Four of nine dogs that underwent bilateral single-surgery TCS placement developed SSI unilaterally. No significant difference was shown in short-term SSI occurrence between the ML and the LM direction of placement of the TCS.

Balance Assessment Using a Smartwatch Inertial Measurement Unit with Principal Component Analysis for Anatomical Calibration

Balance assessment, or posturography, tracks and prevents health complications for a variety of groups with balance impairment, including the elderly population and patients with traumatic brain injury. Wearables can revolutionize state-of-the-art posturography methods, which have recently shifted focus to clinical validation of strictly positioned inertial measurement units (IMUs) as replacements for force-plate systems. Yet, modern anatomical calibration (i.e., sensor-to-segment alignment) methods have not been utilized in inertial-based posturography studies. Functional calibration methods can replace the need for strict placement of inertial measurement units, which may be tedious or confusing for certain users. In this study, balance-related metrics from a smartwatch IMU were tested against a strictly placed IMU after using a functional calibration method. The smartwatch and strictly placed IMUs were strongly correlated in clinically relevant posturography scores (r = 0.861–0.970, p &lt; 0.001). Additionally, the smartwatch was able to detect significant variance (p &lt; 0.001) between pose-type scores from the mediolateral (ML) acceleration data and anterior-posterior (AP) rotation data. With this calibration method, a large problem with inertial-based posturography has been addressed, and wearable, “at-home” balance-assessment technology is within possibility.

Utilizing the ISway to Identify and Compare Balance Domain Deficits in People with Multiple Sclerosis

Background and Purpose Balance impairments are a common symptom in people with Multiple Sclerosis (PwMS). The instrumented sway (ISway) is a reliable clinical balance assessment; however, this approach yields a vast range of outcomes that may hinder interpretation and delivery of evidence-based care. Identifying balance domains that are both altered in PwMS and clinically relevant would help isolate treatment targets. Therefore, we sought to develop a multiple sclerosis (MS)-specific model of balance and examine differences between 1) PwMS and neurotypical controls and 2) PwMS with (MS-F) and without a fall history (MS-NF). Methods 118 people with relapsing-remitting MS (MS-F = 39; MS-NF = 79) and 46 age-matched neurotypical controls completed the ISway balance assessment. 22 sway measures obtained from the ISway were entered into an exploratory factor analysis (EFA) to identify underlying balance domains. The model-derived balance domains were compared between 1) PwMS and age-matched, neurotypical controls and 2) MS-F and MS-NF. Results 3 distinct balance domains were identified: 1) sway amplitude and velocity, 2) sway frequency and jerk mediolateral (ML), and 3) sway frequency and jerk anteroposterior (AP), explaining 81.66% of balance variance. PwMS exhibited worse performance (i.e., greater amplitude and velocity of sway) in the sway velocity and amplitude domain compared to age-matched neurotypical controls (p = .003). MS-F exhibited worse performance in the sway velocity and amplitude domain compared to MS-NF (p = 0.046). The AP and ML sway frequency and jerk domains were not different between PwMS and neurotypical controls nor between MS-F and MS-NF. Discussion PwMS exhibited deficits within the sway amplitude and velocity domain compared to neurotypical controls, with a similar effect observed between MS-F and MS-NF. Recognizing balance domains altered in PwMS and related to falls may be useful for efficient and strategic balance assessment and rehabilitation. Balance impairments are a common symptom in people with Multiple Sclerosis (PwMS). The instrumented sway (ISway) is a reliable clinical balance assessment; however, this approach yields a vast range of outcomes that may hinder interpretation and delivery of evidence-based care. Identifying balance domains that are both altered in PwMS and clinically relevant would help isolate treatment targets. Therefore, we sought to develop a multiple sclerosis (MS)-specific model of balance and examine differences between 1) PwMS and neurotypical controls and 2) PwMS with (MS-F) and without a fall history (MS-NF). 118 people with relapsing-remitting MS (MS-F = 39; MS-NF = 79) and 46 age-matched neurotypical controls completed the ISway balance assessment. 22 sway measures obtained from the ISway were entered into an exploratory factor analysis (EFA) to identify underlying balance domains. The model-derived balance domains were compared between 1) PwMS and age-matched, neurotypical controls and 2) MS-F and MS-NF. 3 distinct balance domains were identified: 1) sway amplitude and velocity, 2) sway frequency and jerk mediolateral (ML), and 3) sway frequency and jerk anteroposterior (AP), explaining 81.66% of balance variance. PwMS exhibited worse performance (i.e., greater amplitude and velocity of sway) in the sway velocity and amplitude domain compared to age-matched neurotypical controls (p = .003). MS-F exhibited worse performance in the sway velocity and amplitude domain compared to MS-NF (p = 0.046). The AP and ML sway frequency and jerk domains were not different between PwMS and neurotypical controls nor between MS-F and MS-NF. PwMS exhibited deficits within the sway amplitude and velocity domain compared to neurotypical controls, with a similar effect observed between MS-F and MS-NF. Recognizing balance domains altered in PwMS and related to falls may be useful for efficient and strategic balance assessment and rehabilitation.

Determining an optimal posturography dataset to identify standing behaviors in the post-stroke subacute phase. Cross-sectional study.

A key issue for posturography is the expression of robust results, in a simplified way. Most studies of individuals post-stroke concern the chronic phase, with small sample sizes. By reducing the number of posturographic indices, we aimed to determine an optimal dataset and understand typical postural behaviors in the subacute post-stroke phase. In this cross-sectional study ancillary to the DOBRAS cohort, individuals were assessed as soon they could complete a full posturography session (with and without vision) after a first hemispheric stroke. Body-weight distribution on the mediolateral (ML) axis, position of the center of pressure on the antero-posterior (AP) axis, and postural sway on both axes were computed. Balance ability in daily life was quantified with the Postural Assessment Scale for Stroke. Data were analyzed by principal component and hierarchical clustering analyses as well as multiple linear regression. We enrolled 95 individuals (median age: 67.0 years [Q1; Q3 56.0; 72.0]; 68% males). Vision suppression had a marginal effect, only increasing postural sway. Regardless of the visual condition, posturographic behavior was captured by a set of 3 indices that explained almost all the information. One postural sway index (ML or AP) gave more information (48%) than both position indices (ML 26% and AP 15%). These 3 indices identified 3 standing behaviors: 1) stable and symmetric, 2) asymmetric, unstable, and positioned backward, and 3) very unstable and positioned forward. Balance ability in daily life was explained (49% of the information, 95%CI [35; 63]) by weight-bearing asymmetry and postural sway on the ML axis, which played an independent role (both p<10-5), with similar impact. Three typical behaviors allow standing after stroke: described by only 3 posturographic indices. Weight-bearing asymmetry is not the primary parameter and should not be considered in isolation as an outcome. To increase the feasibility of posturography in the early subacute phase and to simplify evaluation sessions, trials could be limited to eyes open. NCT03203109.

Hearing Status and Static Postural Control of Collegiate Athletes.

Because of the close proximity of the cochlea, vestibular apparatus, and shared neurovascular structures, the static postural control of athletes who are deaf or hard of hearing (D/HoH) may be different from that of athletes who are hearing. Limited research is available to quantify differences between these athletes. To determine the effect of hearing status and stance condition on the static postural control of athletes. Cross-sectional study. Athletic training facilities. Fifty-five collegiate varsity athletes who were D/HoH (age = 20.62 ± 1.80 years, height = 1.73 ± 0.08 m, mass = 80.34 ± 18.92 kg) and 100 university club athletes who were hearing (age = 20.11 ± 1.59 years, height = 1.76 ± 0.09 m, mass = 77.66 ± 14.37 kg). Participants completed the Modified Clinical Test of Sensory Interaction and Balance on a triaxial force plate. Anteroposterior and mediolateral (ML) center-of-pressure (CoP) velocity, anteroposterior and ML CoP amplitude root mean square, and 95% ellipse sway area were calculated. Athletes who were D/HoH had a larger CoP velocity, larger ML root mean square, and larger sway area than those who were hearing (P values < .01). A significant main effect of stance condition was observed for all postural control variables (P values < .01). During the Modified Clinical Test of Sensory Interaction and Balance, athletes who were D/HoH demonstrated a larger sway area compared with athletes who were hearing. Therefore, individualized baseline assessments of static postural control may be warranted for athletes who are D/HoH as opposed to comparisons with existing normative data.

Relationship between Stress Shielding and Optimal Femoral Canal Contact Regions for Short, Tapered-Wedge Stem Analyzed by 2D and 3D Systems in Total Hip Arthroplasty.

Although tapered-wedge short stem has been widely employed with its availability for minimally invasive surgeries in total hip arthroplasty (THA), post-operative stress shielding matter remains unresolved in cementless procedures. This study aimed to clarify the most optimal femoral canal contact regions of the stem design taking stress shielding incidence into consideration. This investigation included 60 joints from 60 patients (mean age at operation: 65.9 years), of which follow-up duration after primary THA had been more than 2 years. Frequencies of spot welds, subsidence, and stress shielding were examined 2 years after surgery. The most suitable femoral canal contact regions were evaluated by plain radiograph (2D) and 3D-computed tomography analyses according to Nakata's division for fitting manners. Spot welds were observed in 38 cases (63.3%), and no subsidence case was seen. Respective number of stress shielding cases, based on Engh's classification, categorized as degree 0, 1, and 2, were 2 (3.3%), 31 (51.7%), and 27 (45.0%), while no cases for degree 3 or 4 were found. When assessed by 3D fitting analysis, 27 cases of stress shielding degree 2 were constituted by 13/42 cases of mediolateral (ML) fit, 2/4 cases of flare fit, and 12/14 cases of multi point fit. In 42 cases of ML fitting, stem contact rate of the most proximedial region in stress shielding degree 0 and 1 was significantly higher compared to stress shielding degree 2 cases. Meanwhile, the rates of distal regions were significantly lower or absent in stress shielding degree 0 and 1 cases. The initial fixation of this stem design was very good in our cohort regardless of fitting manners. This study successfully revealed that ML fitting with femoral component, especially the most proximedial calcar site restricted fitting, would be optimal for reducing stress shielding occurrence in cementless short, tapered-wedge stem THA. Thus, the ideal stem contact region should be considered during THA procedures in light of the reduction of stress shielding development.

Can a rigid antipronation foot orthosis change the effects of prolonged standing on postural control in men with patellofemoral pain?

Pronated foot posture is known as a contributing factor for patellofemoral pain (PFP) development. Patients with patellofemoral pain often experience poor postural control. Implementation of optimal management strategies for enhancing their postural performance is important. The aim of this study was to determine whether a rigid antipronation foot orthosis changes prolonged standing effects on postural control in men with PFP. Case-control study. Twenty-eight men with PFP and pronated foot and 28 healthy men were enrolled in this study. Center-of-pressure parameters were measured during short trials (60 seconds) of single-leg standing before and immediately after prolonged standing (20 minutes) using force platform. In patients with PFP, postural control was examined on 2 separate days with and without rigid antipronation foot orthosis. Findings showed that the pre-post differences of sway area (t(48) = -2.22, p = 0.03), mediolateral (ML) displacement (t (48) = -2.51, p = 0.01), and mean velocity (t(48) = -2.01, p = 0.04) were significantly greater in patients with PFP without foot orthosis compared with those in the healthy group. Significant intervention main effect ( p = 0.04) and time-by-intervention interaction ( p = 0.006) for sway area were shown. Significant intervention main effects were noted for ML displacement ( p = 0.007) and mean velocity ( p = 0.003). For these variables, significant time-by-intervention interactions were found. Further analysis showed greater values of ML displacement and mean velocity parameters before the prolonged standing in patients with PFP without foot orthosis compared with patients with PFP with orthosis. Rigid antipronation foot orthosis can improve the postural performance after prolonged standing in young adult men with PFP.

Oxygen consumption and gait dynamics in transfemoral bone-anchored prosthesis users compared to socket-prosthesis users: A cross-sectional study

BackgroundA transfemoral bone-anchored prosthesis (BAP) is an alternative for the conventional socket-suspended prosthesis (SSP) in persons suffering from socket-related problems. In these persons, it has been demonstrated to reduce oxygen consumption during walking, which could be related to centre of mass (CoM) and trunk dynamics. However, it remains uncertain whether the same comparative findings are found in SSP-users without any socket-related problems. Research questionDo oxygen consumption, CoM and trunk dynamics during walking differ between satisfied transfemoral SSP- and BAP-users and able-bodied individuals (AB); and are CoM and trunk dynamics and pistoning potential determinants of oxygen consumption? MethodsOxygen consumption was measured while participants walked on a treadmill at preferred speed, 30 % slower, and 30 % faster. At preferred speed, we also evaluated CoM deviation, root-mean-square values (RMS) of mediolateral (ML) CoM and trunk excursions, and pistoning. In the prosthetic users, we evaluated whether oxygen consumption, CoM and trunk dynamics, and pistoning were associated. ResultsWe included BAP-users (n = 10), SSP-users (n = 10), and AB (n = 10). SSP-users demonstrated higher oxygen consumption, CoM and trunk RMS ML in comparison to AB during walking. BAP-users showed intermediate results between SSP-users and AB, yet not significantly different from either group. Greater CoM and trunk excursions were associated with higher oxygen consumption; in the SSP-users a greater degree of pistoning, in turn, was found to associate with larger trunk RMS ML. SignificanceOur results indicate that satisfied SSP-users have increased oxygen consumption compared to AB subjects and use compensatory movements during walking. An assessment of CoM and trunk dynamics, and pistoning during walking may be considered for evaluating whether an individual SSP-user could possibly benefit from a BAP, in addition to the currently used functional tests for evaluating eligibility. This might lead to a larger group of persons with a transfemoral SSP benefiting from this technology.

Pelvis perturbations in various directions while standing in staggered stance elicit concurrent responses in both the sagittal and frontal plane.

Increasing knowledge on human balance recovery strategies is important for the development of balance assistance strategies using assistive devices like a powered lower-limb exoskeleton. One of the postures which is relevant for this scenario, but underexposed in research, is staggered stance, a posture with one foot in front. We therefore aimed to gain a better understanding of balance recovery in staggered stance. We studied balance responses at joint- and muscle levels to pelvis perturbations in various directions while standing in this posture. Ten healthy individuals participated in this study. We used one actuator beside and one behind the participant to apply 150 ms perturbations in mediolateral (ML), anteroposterior (AP) and diagonal directions, with a magnitude of 3, 6, 9 and 12% of the participant's body weight (BW). Meanwhile, motion capture, ground reaction forces and moments, and electromyography of the muscles around the ankles and hips were recorded. The perturbations caused movements of the centre of mass (CoM) and centre of pressure (CoP) in the direction of the perturbation. These were often accompanied by motions in a direction different from the perturbation direction. After perturbations perpendicular to the line between both feet, large and significant AP deviations were present of the CoM (-0.27 till 0.40 cm/%BW, p < 0.029) and CoP (-0.99 till 0.80 cm/%BW, p < 0.001). Also, stronger responses on joint and muscle level were present after these perturbations, compared to AP and diagonal perturbations collinear with the line between both feet. The hip, knee and ankle joints contributed differently to the balance responses after the different perturbation directions. To conclude, standing in a staggered stance posture makes individuals more vulnerable to perturbations perpendicular to the line between both feet, requiring larger responses on joint level as well as contributions in the sagittal plane.

Mountain Hiking: Prolonged Eccentric Muscle Contraction during Simulated Downhill Walking Perturbs Sensorimotor Control Loops Needed for Safe Dynamic Foot–Ground Interactions

Safe mountain hiking requires precise control of dynamic foot-ground interactions. In addition to vision and vestibular afferents, limb proprioception, sensorimotor control loops, and reflex responses are used to adapt to the specific nature of the ground contact. Diminished leg dexterity and balance during downhill walking is usually attributed to fatigue. We investigated the supplementary hypothesis that the eccentric contractions inherent to downhill walking can also disrupt muscle proprioception, as well as the sensorimotor control loops and reflex responses that depend on it. In this study, we measured leg dexterity (LD), anterior-posterior (AP) and medio-lateral (ML) bipedal balance, and maximal voluntary leg extension strength in young and healthy participants before and after 30 min of simulated downhill walking at a natural pace on a treadmill at a 20° decline. Post-pre comparisons of LD (p < 0.001) and AP balance (p = 0.001) revealed significant reductions in dynamic foot-ground interactions after eccentric exercise without an accompanying reduction in leg extension strength. We conclude that eccentric contractions during downhill walking can disrupt the control of dynamic foot-ground interactions independently of fatigue. We speculate that mountaineering safety could be improved by increasing conscious attention to compensate for unadjusted proprioception weighting, especially in the descent.

The effects of optic flow on postural stability: Influence of age and fall risk

BackgroundOptic flow provides dynamic information relating to body position and motion with respect to visual frames of reference. This study investigated the effects of optic flow stimuli presented in four directions on postural stability in young and older adults. MethodsTwenty-five young (20–40 years) and 51 older (≥65 years) people participated in this study, with the older group classified into low fall risk (n = 27), and high fall risk (n = 24) sub-groups. While standing in a dark room, participants viewed static scattered white dots for 30 s, followed by 30 s periods of optic flow consisting of white dots “moving” in one of four flow directions, randomised: radial expansion and contraction, circular anti-clockwise and clockwise. Centre of pressure (CoP) position, postural sway in anteroposterior (AP) and mediolateral (ML) axes, and muscle activity of tibialis anterior (TA), gastrocnemius medialis (GM) and tensor fascia latae (TFL) were recorded. ResultsAcross groups, the four optic flow stimuli induced increased AP sway and three of the four optic flow stimuli induced increased ML sway, with concomitant increases in muscle activity, indicating optic flow stimuli induced a generalised destabilising, rather than a direction-specific, effect. Only one optic flow condition (radial contraction) induced a change in average CoP position, and this may reflect the adoption of a protective stance position to avoid a backward fall. Optic flow destabilised postural control more in older people compared with younger people, and radial expansion stimuli destabilised ML postural control more in the older high fall risk group compared with the older low fall risk group. ConclusionOptic flow stimuli have a generalised destabilising effect on postural control across groups as shown by non-directional specific increases in postural sway and muscular activity. Optic flow stimuli have a greater impact on postural stability in older compared with younger adults and this is more pronounced in the ML plane for older people at increased risk of falls.

Whole body MRI with DWI in people with NF1 and Schwannomatosis: Are qualitative and quantitative imaging features of peripheral lesions comparable to localized MRI?

PurposeTo compare the qualitative and quantitative features of peripheral lesions on localized (L) and whole-body (WB) magnetic resonance imaging (MRI) in people with neurofibromatosis type 1 (NF1) and schwannomatosis. Materials and methodsThis is a retrospective, HIPAA compliant study with twenty-seven patients (14 women, 13 men; mean age (years): 38 (3–67)) who underwent both L-MRI and WB-MRI without interval treatment. WB-MRI and L-MRI were comprised of T1-weighted, fat suppressed (FS) T2-weighted or short tau inversion recovery (STIR), diffusion-weighted imaging (DWI) using b-values of 50, 400, and 800 s/mm2, apparent diffusion coefficient (ADC) mapping and pre- and post-contrast FST1 sequences. Two readers recorded qualitative (T1 and T2/STIR signal intensity and heterogeneity, contrast enhancement and heterogeneity, perilesional enhancement, presence of a target sign and perilesional edema) and quantitative (size, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), ADC) features of peripheral lesions on L-MRI and WB-MRI.Descriptive statistics, Wilcoxon signed-rank test and McNemar’s test were used. ResultsThere were 31 peripheral lesions identified in 27 subjects, (mean size: 3.1 cm (range: 1–8.1 cm) on both L-MRI and WB-MRI).There were no differences in T1 signal and heterogeneity and T2/STIR signal and heterogeneity between WB-MRI and L-MRI ((p = 0.180, 0.083, 0.317 and 0.157 respectively). There were also no differences in contrast enhancement, heterogeneity and perilesional enhancement between WB-MRI and L-MRI (p = 1.000, 0.380 and 1.000 respectively). Presence of a target sign and perilesional edema did not differ between WB-MRI and L-MRI (p = 1.000 and 0.500 respectively). Craniocaudal (CC), mediolateral (ML) and anteroposterior (AP) size measurements on WB-MRI did not differ from CC, ML and AP size measurements on L-MRI (p = 0.597, 0.128 and 0.783 respectively). SNR on WB-DWI did not differ from SNR on L-DWI for b50, b400 and b800 images (p = 0.285, 0.166, and 0.974 respectively), and CNR on WB-DWI did not differ from CNR on L-DWI for b50, b400 and b800 images (p = 0.600, 0.124, and 0.787 respectively). There was no significant difference in minimum, mean and maximum ADC values between WB-DWI and L-DWI (p = 0.234, 0.481, and 0.441 respectively). Median minimum, mean and maximum ADC (×10(-3)mm(2)/s) differences between WB-DWI and L-DWI were 0.0 (range −1 to 0.7), 0.0 (range −0.5 to 0.6), and 0.1 (range −1.2 to 0.8) respectively. Relative ADC difference averages were 29.1% for minimum values, 10.1% for mean values, and 14.8% for maximum values. ConclusionWB-MRI yields qualitative and quantitative features for peripheral lesions, including DWI and ADC measurements, that are comparable to L-MRI scans. WB-DWI can be reliably used for the assessment of peripheral nerve sheath tumors, obviating the need for a repeat follow-up L-DWI acquisition.

Investigation of gait and balance function in cervical spondylotic myelopathy patients using wearable sensors

Background ContextCervical spondylotic myelopathy (CSM) is a degenerative disease caused by cervical cord compression and can lead to the significant impairment of motor function including gait and balance disturbances and changes in lower extremity muscle activity. PurposeThis study aimed to characterize gait, balance and lower extremity muscle activity in patients with CSM compared to age-matched healthy controls (HCs) using wearable sensors in the clinical setting. Study DesignNonrandomized, prospective cohort study. Patient SampleTen CSM patients and 10 age-matched HCs were recruited for this study. Outcome MeasuresGait and balance function parameters contained spatial temporal parameters, step regularity (SR1), stride regularity (SR2) and harmonic ratio (HR). EMG muscle activity parameters included time to peak and peak value during loading, stance, and swing phase. MethodsIn this study, parameters of gait and balance function were extracted using triaxial accelerometer attached to the spinous processes of Lumbar 5 while participants performed an overground walking at a self-preferred speed. Moreover, muscular activity was simultaneously recorded via sEMG sensors attached to tibialis anterior (TA), rectus femoris (RF), bicep femoris (BF), and gastrocnemius lateral (GL). Independent sample t test was used to find the differences between CSM patients and HCs. ResultsGait analysis showed cadence, step length and walking speed were statistically significantly lower in CSM patients than HCs. Stride time was significantly higher for CSM patients in comparison to HCs. Lower root mean square ratio (RMSR) of acceleration in the mediolateral (ML) direction, HR in the anteroposterior (AP) direction, SR1 in the AP direction and SR2 in all three directions were observed in CSM patients. For muscle activity analysis, EMG RMS for TA and RF during loading phase and RMS for GL during midstance phase was significantly lower for CSM patients, while significantly higher value was observed for RF RMS during midstance phase and GL RMS during swing phase in CSM patients. ConclusionOur pilot study shows that wearable sensors are able to detect the changes of gait, balance and lower extremity muscle activities of CSM patients in the clinical setting. This pilot study sets the stage for future researches on the diagnosis and monitor progression of CSM disease using wearable technology.

Gap Balancing Throughout the Arc of Motion With Navigated TKA and a Novel Force-Controlled Distractor: A Review of the First 273 Cases

BackgroundThis study evaluated the ability to achieve the targeted soft-tissue balance in terms of medio-lateral (ML) laxity and gap values when using a computer-assisted orthopedic surgery (CAOS) system featuring an intra-articular force-controlled distractor and assessed learning curves associated with the adoption of this technology. MethodsThe first 273 cases using this technology were reported without exclusions comparing 1) final ML laxity and 2) final average gap to their predefined targets. For both parameters, the signed and unsigned differentials were reported. The linear mixed model was used to evaluate laxity curve differences between surgeons. A cumulative sum control chart (CUSUM) was applied to assess surgeon learning curves regarding surgical time. ResultsBoth the average signed ML laxity and gap differentials were neutral throughout the full arc of motion. Both the average unsigned ML laxity and gap differentials were linear. Signature of ML laxity and gap differential curves tended to be surgeon-specific. The CUSUM analyses of surgical times demonstrated either a short learning curve or the absence of a discernible learning pattern for surgeons. ConclusionData from all users involved with the pilot release of the balancing device were considered to capture variability in familiarity with the technique and learning curve cases were included. A high ability to achieve targeted gap balance throughout the arc of motion using the proposed method was observed.