Support for a reduction in the number of trials needed for the star excursion balance test

Robinson RH, Gribble PA. Support for a reduction in the number of trials needed for the Star Excursion Balance Test.

Objective

To determine the number of trials necessary to achieve stability in excursion distance and stance leg angular displacement for the 8 directions of the Star Excursion Balance Test (SEBT).

Design

One-way repeated-measures analysis of variance.

Setting

Athletic training laboratory.

Participants

Twenty participants (10 men, 10 women) without any known musculoskeletal injuries or neurologic deficits that could have negatively affected their dynamic balance volunteered for the study.

Intervention

Participants completed 6 practice and 3 test trials in each of the 8 reach directions of the SEBT.

Main Outcome Measures

Excursion distances of the reaching leg normalized to leg length and angular displacement at the hip and knee of the stance leg in all 3 planes of movement were determined.

Results

There were significant increases in excursion distance, hip flexion, and knee flexion for 7, 4, and 5 of the 8 reach directions, respectively.

Conclusions

For the majority of the reach directions, maximum excursion distances and stance leg angular displacement values achieved stability within the first 4 practice trials, thus justifying a reduction in the recommended number of practice trials from 6 to 4 and supporting the trend toward simplifying SEBT administration.     

Kinematic trajectories while walking within the Lokomat robotic gait-orthosis

Background One of the most popular robot assisted rehabilitation devices used is the Lokomat. Unfortunately, not much is known about the behaviors exhibited by subjects in this device. The goal of this study was to evaluate the kinematic patterns of individuals walking inside the Lokomat compared to those demonstrated on a treadmill.Methods Six healthy subjects walked on a treadmill and inside the Lokomat while the motions of the subject and Lokomat were tracked. Joint angles and linear motion were determined for Lokomat and treadmill walking. We also evaluated the variability of the patterns, and the repeatability of measuring techniques.Findings The overall kinematics in the Lokomat are similar to those on a treadmill, however there was significantly more hip and ankle extension, and greater hip and ankle range of motion in the Lokomat (P < 0.05). Additionally, the linear movement of joints was reduced in the Lokomat. Subjects tested on repeated sessions presented consistent kinematics, demonstrating the ability to consistently setup and test subjects.Interpretation The reduced degrees of freedom in the Lokomat are believed to be the reason for the specific kinematic differences. We found that despite being firmly attached to the device there was still subject movement relative to the Lokomat. This led to variability in the patterns, where subjects altered their gait pattern from step to step. These results are clinically important as a variable step pattern has been shown to be a more effective gait training strategy than one which forces the same kinematic pattern in successive steps.     

Validated robotic laparoscopic surgical training in a virtual-reality environment

Background  A robotic virtual-reality (VR) simulator has been developed to improve robot-assisted training for laparoscopic surgery and to enhance surgical performance in laparoscopic skills. The simulated VR training environment provides an effective approach to evaluate and improve surgical performance. This study presents our findings of the VR training environment for robotic laparoscopy. Methods  Eight volunteers performed two inanimate tasks in both the VR and the actual training environment. The tasks were bimanual carrying (BC) and needle passing (NP). For the BC task, the volunteers simultaneously transferred two plastic pieces in opposite directions five times consecutively. The same volunteers passed a surgical needle through six pairs of holes in the NP task. Both tasks require significant bimanual coordination that mimics actual laparoscopic skills. Data analysis included time to task completion, speed and distance traveled of the instrument tip, as well as range of motion of the subject’s wrist and elbow of the right arm. Electromyography of the right wrist flexor and extensor were also analyzed. Paired t-tests and Pearson’s r were used to explore the differences and correlations between the two environments. Results  There were no significant differences between the actual and the simulated VR environment with respect to the BC task, while there were significant differences in almost all dependent parameters for the NP task. Moderate to high correlations for most dependent parameters were revealed for both tasks. Conclusions  Our data shows that the VR environment adequately simulated the BC task. The significant differences found for the NP task may be attributed to an oversimplification in the VR environment. However, they do point to the need for improvements in the complexity of our VR simulation. Further research work is needed to develop effective and reliable VR environments for robotic laparoscopic training.     

Robotic movement elicits visuomotor priming in children with autism

The ability to understand another person's action and, if needed, to imitate that action, is a core component of human social behaviour. Imitation skills have attracted particular attention in the search for the underlying causes of the social difficulties that characterize autism. In recent years, it has been reported that people with autism can bypass some of their social deficits by interacting with robots. However, the robot preference in terms of imitation has yet to be proved. Here we provide empirical evidence that interaction with robots can trigger imitative behaviour in children with autism. We compared a group of high functioning children with autism with a group of typically developing children in a visuomotor priming experiment. Participants were requested to observe either a human or a robotic arm model performing a reach-to-grasp action towards a spherical object. Subsequently, the observers were asked to perform the same action towards the same object. Two 'control' conditions in which participants performed the movement in the presence of either the static human or robot model were also included. Kinematic analysis was conducted on the reach-to-grasp action performed by the observer. Our results show that children with autism were facilitated - as revealed by a faster movement duration and an anticipated peak velocity - when primed by a robotic but not by a human arm movement. The opposite pattern was found for normal children. The present results show that interaction with robots has an effect on visuomotor priming processes. These findings suggest that in children with autism the neural mechanism underlying the coding of observed actions might be tailored to process socially simpler stimuli.     

Impact of Morbid Obesity on Chewing Ability

Background  This study compared the chewing parameters in a group of obese adult patients scheduled for gastric bypass surgery with those of a control group. Methods  Chewing parameters were measured in two groups of subjects, one of 44 obese patients scheduled for gastric bypass surgery (body mass index [BMI] = 49.1 ± 7.2) and the other of 30 non-obese control subjects (BMI = 20.9 ± 2.1). In both groups, the subjects’ dental status was characterized by the number of functional dental units. Kinematic parameters, namely chewing time (CT), number of chewing cycles (CC), and chewing frequency (CF), were video recorded during the mastication of five natural standardized foods (banana, apple, sweet jelly, peanut, and carrot). The particle size distribution of the expectorated bolus from carrot and peanuts was characterized by the 50th percentile (D ₅₀). Analysis was carried out to detect any effect of the fixed factors “dental status,” “type of food,” and “subject group” on the variations of the dependent factors CT, CC, CF, and D ₅₀. Results  In obese subjects, CT, CC, and D ₅₀ were variables depending on both dental status and food. For fully dentate subjects, the group of patients with obesity showed higher values for CT and CC and lower values for D ₅₀ for both carrot and peanuts than the control group. Conclusion  The chewing parameters were affected in fully dentate patients with morbid obesity compared with controls, emphasizing the need for a systematic evaluation of both dental status and chewing ability in patients scheduled for bariatric surgery.     

Patellar resurfacing has minimal impact on in vitro tibiofemoral kinematics during deep knee flexion in total knee arthroplasty

BackgroundWhile patellar resurfacing can affect patellofemoral kinematics, the effect on tibiofemoral kinematics is unknown. We hypothesized that patellar resurfacing would affect tibiofemoral kinematics during deep knee flexion due to biomechanical alteration of the extensor mechanism.MethodsWe performed cruciate-retaining TKA in fresh-frozen human cadaveric knees (N = 5) and recorded fluoroscopic kinematics during deep knee flexion before and after the patellar resurfacing. To simulate deep knee flexion, cadaver knees were tested on a dynamic, quadriceps-driven, closed-kinetic chain simulator based on the Oxford knee rig design under loads equivalent to stair climbing. To measure knee kinematics, a 2-dimensional to 3-dimensional fluoroscopic registration technique was used. Component rotation, varus-valgus angle, and anteroposterior translation of medial and lateral contact points of the femoral component relative to the tibial component were calculated over the range of flexion.ResultsThere were no significant differences in femoral component external rotation (before patellar resurfacing: 6.6 ± 2.3°, after patellar resurfacing: 7.2 ± 1.8°, p = 0.36), and less than 1° difference in femorotibial varus-valgus angle between patellar resurfacing and non-resurfacing (p = 0.01). For both conditions, the medial and lateral femorotibial contact points moved posteriorly from 0° to 30° of flexion, but not beyond 30° of flexion. At 10° of flexion, after patellar resurfacing, the medial contact point was more anteriorly located than before patellar resurfacing.ConclusionDespite the potential for alteration of the knee extensor biomechanics, patellar resurfacing had minimal effect on tibiofemoral kinematics. Patellar resurfacing, if performed adequately, is unlikely to affect postoperative knee function.     

An index for the evaluation of 3D masticatory cycles stability

ObjectivesTo introduce an index (Masticatory Stability Index, MSI) to analyze the stability of chewing cycles in standardized conditions and test it in a group of patients with subclinical mild temporomandibular disorder (TMD).Design23 subjects with mild subacute TMD and 21 healthy subjects were involved; they all responded to a questionnaire about signs and symptoms of TMD (ProTMDmulti) and underwent a myofunctional orofacial evaluation with scores, using the protocol of orofacial myofunctional evaluation with scores (OMES). Their mandibular kinematics was assessed with a 3D motion capture system during deliberate unilateral gum chewing. The MSI was computed synthesizing the information contained in nine kinematics parameters into a single global figure. Patients’ and controls’ MSI were compared considering the preferred and non-preferred chewing side using a 2-way ANOVA (factors: group, side).ResultsTogether with a lower total score of myofunctional orofacial status, the TMD group showed a reduced stability based on MSI (p < 0.05).ConclusionsThe MSI is an efficient method to measure the stability of the masticatory cycles. These preliminary results encourage validating the index on a larger sample. The variability in the motor behavior of chewing can impair the objectivity of its evaluations in several types of patients, including those with TMD. The MSI could be useful to complement clinical assessments, providing data for planning the rehabilitation of masticatory function in these patients.     

Gait difference between children aged 9 to 12 with and without potential depressive mood

BackgroundIt has been reported that depression has an impact on both temporal spatial parameters and walking kinematics in adults. Given the difference in the walking biomechanics between adults and children, this study aimed to compare the gait difference in children aged 9–12 with and without potential depressive mood (PDM).Methods49 children were recruited from local primary schools. We measured participants’ depression level using Depression Anxiety Stress Scale (DASS) and classified them into control (i.e., DASS depression subscale score = 0.6 ± 1.4; n = 23) or PDM group (i.e., DASS depression subscale score = 21.3 ± 5.3; n = 26). Video gait analysis was employed to assess temporal spatial parameters and sagittal plane kinematics during self-paced overground walking. Independent t tests or Mann-Whitney tests were used to compare the gait parameters between the two groups.ResultsParticipants exhibited similar gait speed, vertical oscillation of the centre of mass, stance time, swing time, step length, upper and lower limb kinematics between the two groups (p > 0.05). However, children with PDM displayed a greater head flexion than controls (p = 0.026; Cohen’s d = 0.66; moderate effect).SignificanceChildren with PDM may present a more slumped posture during walking when compared with their counterparts. This kinematics difference can potentially be used as a biomechanical marker for detection of mood problems in this cohort.     

Patients with chronic non-specific low back pain have altered movement coordination during functional reaching tasks

BackgroundIdentifying altered motor control patterns during functional movements in patients with chronic non-specific low back pain (LBP) has important clinical implications for reducing the risk of recurrence. While prior research has shown that magnitudes of lumbar and hip motion are not altered in patients with chronic non-specific LBP, it is possible that outcomes which describe coordination could provide greater discriminatory information between pathological and healthy movement.Research questionDetermine the effect of biological sex and chronic non-specific LBP on coordination between hip and lumbar motion during cyclic and discrete reaching.MethodsTwenty participants with chronic non-specific LBP (11 male/9 female, 23.5 ± 4.9 years old) and 21 control participants (12 male/9 female, 22.9 ± 6.1 years old) completed discrete and cyclic reaching tasks to a target in the mid-sagittal plane, while whole-body kinematics were collected using a three-dimensional motion capture system. Movement time, lumbar motion, hip motion, and the ratio between lumbar and hip motion were compared between participants with and without chronic non-specific LBP and between men and women using two-way mixed ANOVAs.ResultsParticipants with chronic non-specific LBP had reduced lumbar-hip ratios relative to control participants during both the cyclic (F = 4.779, p = 0.035, η² = 0.114) and discrete tasks (F = 4.743, p = 0.036, η² = 0.119), however group differences were not observed for hip or lumbar excursion during either task (p > 0.05). Participants with chronic non-specific LBP had slower reaching times relative to controls during the discrete reaching task (F = 4.795, p = 0.035, η² = 0.115). No significant effects of sex, and no interactions between group and sex were observed for any outcome.SignificanceReduced lumbar-hip ratios during reaching likely reflect a compensatory movement strategy that could play an important role in the development and progression of LBP.