Repeatability and reproducibility of the Tekscan HR-Walkway system in healthy children

This study investigated the repeatability and reproducibility of the HR Walkway system with regards to peak pressure values (PP) and pressure time integral (PTI) in healthy children, ranging between 5 and 18 years of age. Subjects recruited took part in two non-invasive clinical assessments, at baseline and 1 week later. Gait analysis was carried out using the PP box approach, and plantar foot recording was divided into 10 anatomical areas. The PP and PTI was investigated for the left, right and both feet accounted together. Interclass Correlation Coefficient (ICC) test was adopted for statistical analysis. Overall, 30 healthy patients were recruited and 60 appointments were completed, 53.3% (n = 16) were female and 46.7% (n = 14) were male. Mean age was 13.3 years (SD = 4.5), with an age-range of 5–18.6 years old. Results indicated that for all variables tested the repeatability data were ‘good’ ICC for 73.8% (n = 121) and ‘moderate’ ICC for 26.2% (n = 43). For all variables tested, the reproducibility data showed that ‘good’ ICC for 70.7% (n = 58) and ‘moderate’ ICC for 29.3% (n = 24). In conclusion, the HR Walkway system is able to provide repeatable and reproducible data.     

Markerless motion capture can provide reliable 3D gait kinematics in the sagittal and frontal plane

Estimating 3D joint rotations in the lower extremities accurately and reliably remains unresolved in markerless motion capture, despite extensive studies in the past decades. The main problems have been ascribed to the limited accuracy of the 3D reconstructions. Accordingly, the purpose of the present study was to develop a new approach based on highly detailed 3D reconstructions in combination with a translational and rotational unconstrained articulated model. The highly detailed 3D reconstructions were synthesized from an eight camera setup using a stereo vision approach. The subject specific articulated model was generated with three rotational and three translational degrees of freedom for each limb segment and without any constraints to the range of motion. This approach was tested on 3D gait analysis and compared to a marker based method. The experiment included ten healthy subjects in whom hip, knee and ankle joint were analysed. Flexion/extension angles as well as hip abduction/adduction closely resembled those obtained from the marker based system. However, the internal/external rotations, knee abduction/adduction and ankle inversion/eversion were less reliable.     

Selective dorsal rhizotomy: long-term experience from Cape Town

Introduction Given the large number of cerebral palsy patients who have undergone selective dorsal rhizotomy in the past two decades, it is clearly imperative that the clinical community be provided with objective and compelling evidence of the long-term sequelae of the procedure. Materials and methods In the early 1980s, Peacock in Cape Town shifted the site of the rhizotomy from the conus medullaris to the cauda equina, and in the past 25 years, more than 200 children have been operated on. We have studied the incidence of spinal deformities after multiple-level laminectomy and recorded a 20% incidence of isthmic spondylolysis or grade-I spondylolisthesis. We have also conducted a long-term prospective gait analysis study on a cohort of 14 ambulatory patients who were operated on in 1985. Results Ten years after surgery, our patients had increased ranges of motion that were within normal limits. Step length was significantly improved, although cadence was unchanged postoperatively and was significantly less than normal age-matched control subjects. Discussion We have recently tracked down all 14 patients from the original cohort and are currently completing a 20-year prospective follow-up analysis of their neuromuscular function and gait. Our preliminary data suggest that selective dorsal rhizotomy is not only an effective method for alleviating spasticity but it also leads to long-term functional benefits.     

减重平板训练对瘫痪后步行障碍患者的影响

目的：观察减重平板训练对脊髓损伤和脑损伤造成的长期下肢瘫痪步行功能的作用。方法：10名男性患者，年龄25－64岁，其中4例脊髓损伤，6例脑血管意外，病程平均1．4年，减重平板训练前均接受不同程度的传统康复训练，功能步行评定为0－1分，接受减重平板训练每天1次，开始减重重量在50％－70％之间，平板速度为0．27m/s，平均20次，所有虱训练前后接受功能步行和一般平衡功能测定，其中7例患者在Kistler压电晶体式三维测力台上进行步态分析。结果：患者经过阶段性减重平板训练，功能性步行评定及站立平衡功能比传统康复治疗前后有十分明显的改善（P＜0．0001，P＝0．0003），其中7例患者的平均步速达0．36m/s，左右足对台压力峰值和支撑时间无明显差异（P＞0．05），结论：减重平板训练对长期瘫痪患者改善步行能力有帮助。     

Robotic gait trainer in water: Development of an underwater gait-training orthosis

Purpose.?To develop a robotic gait trainer that can be used in water (RGTW) and achieve repetitive physiological gait patterns to improve the movement dysfunctions.

Method.?The RGTW is a hip-knee-ankle-foot orthosis with pneumatic actuators; the control software was developed on the basis of the angular motions of the hip and knee joint of a healthy subject as he walked in water. Three-dimensional motions and electromyographic (EMG) activities were recorded in nine healthy subjects to evaluate the efficacy of using the RGTW while walking on a treadmill in water.

Results.?The device could preserve the angular displacement patterns of the hip and knee and foot trajectories under all experimental conditions. The tibialis anterior EMG activities in the late swing phase and the biceps femoris throughout the stance phase were reduced whose joint torques were assisted by the RGTW while walking on a treadmill in water.

Conclusion.?Using the RGTW could expect not only the effect of the hydrotherapy but also the standard treadmill gait training, in particular, and may be particularly effective for treating individuals with hip joint movement dysfunction.     

Functional balance assessment in recreational college-aged individuals with a concussion history

Objectives

Despite evidence for increased musculoskeletal injury after concussion recovery, there is a lack of dynamic balance assessments that could inform management and research into this increased injury risk post-concussion. Our purpose was to identify tandem gait dynamic balance deficits in recreational athletes with a concussion history within the past 18-months compared to matched controls.

人体下肢外骨骼机器人的步态研究现状

外骨骼机器人是将人的智慧与机器的机械动力装置相结合的一种机器人,不仅可以为操作者提供保护、身体支撑等功能,还可以在操作者的控制下完成一定的功能和任务,应用前景巨大.文中阐述人体下肢外骨骼机器人下肢外骨骼实现行走应具备的关节及其活动度,介绍下肢外骨骼机器人步态控制的基础--正常步态分析,详细论述了目前控制下肢外骨骼机器人行走及步态稳定性的主要方法.     

The effect of military load carriage on ground reaction forces

Load carriage is an inevitable part of military life both during training and operations. Loads carried are frequently as high as 60% bodyweight, and this increases injury risk. In the military, load is carried in a backpack (also referred to as a Bergen) and webbing, these combined form a load carriage system (LCS). A substantial body of literature exists recording the physiological effects of load carriage; less is available regarding the biomechanics. Previous biomechanical studies have generally been restricted to loads of 20% and 40% of bodyweight, usually carried in the backpack alone. The effect of rifle carriage on gait has also received little or no attention in the published literature. This is despite military personnel almost always carrying a rifle during load carriage. In this study, 15 male participants completed 8 conditions: military boot, rifle, webbing 8 and 16 kg, backpack 16 kg and LCS 24, 32 and 40 kg. Results showed that load added in 8 kg increments elicited a proportional increase in vertical and anteroposterior ground reaction force (GRF) parameters. Rifle carriage significantly increased the impact peak and mediolateral impulse compared to the boot condition. These effects may be the result of changes to the vertical and horizontal position of the body's centre of mass, caused by the restriction of natural arm swing patterns. Increased GRFs, particularly in the vertical axis, have been positively linked to overuse injuries. Therefore, the biomechanical analysis of load carriage is important in aiding our understanding of injuries associated with military load carriage.     

Balance disorder and increased risk of falls in osteoporosis and kyphosis: significance of kyphotic posture and muscle strength

This controlled trial was designed to investigate the influence of osteoporosis-related kyphosis (O-K) on falls. Twelve community-dwelling women with O-K (Cobb angle, 50–65° measured from spine radiographs) and 13 healthy women serving as controls were enrolled. Mean age of the O-K group was 76 years (±5.1), height 158 cm (±5), and weight 61 kg (±7.9), and mean age of the control group was 71 years (±4.6), height 161 cm (±3.8), and weight 66 kg (±11.7). Quantitative isometric strength data were collected. Gait was monitored during unobstructed level walking and during stepping over an obstacle of four different heights randomly assigned (2.5%, 5%, 10%, and 15% of the subjects height). Balance was objectively assessed with computerized dynamic posturography consisting of the sensory organization test. Back extensor strength, grip strength, and all lower extremity muscle groups were significantly weaker in the O-K group than the control group ( P <0.05), except right ankle plantar flexors ( P =0.09). There was a significant difference in the anteroposterior and mediolateral displacements and velocities. The O-K subjects had less anteroposterior displacement, greater mediolateral displacement, reduced anteroposterior velocity, and increased mediolateral velocity compared with controls for all conditions of unobstructed and obstructed level walking. Obstacle height had a significant effect on all center-of-mass variables. The O-K subjects had significantly greater balance abnormalities on computerized dynamic posturography than the control group ( P =0.002). Data show that thoracic hyperkyphosis on a background of reduced muscle strength plays an important role in increasing body sway, gait unsteadiness, and risk of falls in osteoporosis.     

Electronic measurement of plantar contact area during walking using an adaptive thresholding method for Medilogic® pressure-measuring insoles

BackgroundPressure-measuring insoles have the potential to measure plantar contact area (PA) during walking. However, they are not widely used for this purpose because of the need for a reliable process that can convert the insole output into PA. The purposes of this study were to: (1) develop an adaptive-threshold method for pressure-measuring insoles that can improve the accuracy of the PA measurements during walking, and (2) experimentally assess the accuracy and generalizability of this method.MethodsA sample of 42 healthy, ambulatory, young adults (age = 24.3 ± 3.2 years, mass = 67.2 ± 16.9 kg, height = 1.63 ± 0.08 m) completed 10 trials walking on an elevated walkway while wearing Medilogic^® pressure-measuring insoles (sizes 35–45). A total of six insole sizes were considered. Insole data were converted to PA using three unique adaptive-thresholds that were based on percentages of the maximum sum of digital values (MSDV) during an analyzed step. Three values were considered: 0.1%, 0.2%, and 0.3% of the MSDV. Additionally, a fixed-threshold, which is typically used to estimate PA, was assessed. These two techniques, applied to the insole worn on the left foot, were compared with PA obtained from high-resolution reference footprints obtained from optical pedography of the right foot and processed using digital image processing algorithms. An assumption of PA symmetry between the left (insole) and right (barefoot) feet was made and comparisons were conducted over the entire stance phase of walking. The generalizability of the algorithm was assessed by comparing PA errors from insoles with respect to the optical pedography results based on insole size criteria.ResultsThe adaptive-thresholds of 0.1%, 0.2%, and 0.3% of MSDV produced mean errors of 7.31 ± 17.44%, −8.62 ± 15.01%, and −20.45 ± 14.18%, respectively. Using the 2-digital value fixed-threshold produced a mean error of 20.88 ± 22.44%. The best performing adaptive-threshold varied among insole sizes.ConclusionIt was observed that the fixed-threshold technique produced large magnitudes of errors. The proposed adaptive-thresholds of 0.1% and 0.2% of the MSDV reduced PA error to ±10% during walking. The adaptive-threshold method consistently reduced PA error vs. the fixed-threshold for each insole size.