轻便低成本型人体平衡功能测量系统研究与开发进展

人体平衡的控制与保持机制十分复杂,老龄化、中风、肢体残障等因素都会导致人体运动平衡功能的障碍,因此平衡功能的测试与评价在该类相关疾病的诊断与评判中起着至关重要的作用。本文总结了目前人体平衡功能研究的常用设备与方法及其局限,提出了基于微电子传感器系统的穿戴式人体运动捕捉系统、基于体感游戏设计的平衡检测与康复训练系统等几种轻便低价的新型人体平衡测量与训练设备的设计思路与方法。     

Reliability of forearm medial-anterior surface dimensional changes at different isometric hand grip forces

Indirect techniques of predicting hand grip force are fundamental to develop hand control systems for assistive devices. The purpose of this study was to determine the reliability of 3D position of forearm surface at different isometric hand grip forces. Three-dimensional motion analysis was used to measure displacement of 24 discrete and standardized surface markers placed on forearm in 20 healthy participants. The relative displacements were measured for isometric grip forces at 0%, 5%, 20% 50% and 80% of maximum voluntary contraction (MVC). Intraclass correlation coefficient (ICC) for relative radial displacement (RRD) of each marker was calculated. Averaged single measure ICC of 24 markers at five grip forces was 0.61; while the highest averaged single measure ICC (0.80) for all markers was achieved at 80% of MVC and the lowest (0.47) at 0% of MVC. The average measure ICC for each grip force across the 24 markers also increased with grip force from 0.80 at 0% of MVC to the maximum of 0.95 at 80% of MVC. In conclusion, RRD showed moderate and high ICCs for single and average measures respectively. Overall, this study suggests that the reliable dimensional changes of 3D positions of forearm surface might be considered as an indirect and non-invasive method to predict hand grip force in future.     

Effects of a rebound shoe to reduce impact forces in jump-landing tasks

ObjectivesImpact forces are risk factors for injuries during jump-landing tasks. Rebound shoes could reduce impact forces and show potential applications in training and rehabilitation programs. Here, we determine the capacity of a rebound shoe in attenuating impact forces during different motor tasks involving foot landing.DesignCrossover laboratory research design.SettingsWomen not trained for jump-landing tasks performed different exercises while the vertical ground reaction force impact peak, time to peak, and asymmetries were determined. They were wearing a commercial rebound shoe and a control running shoe. Paired t-tests were used to compare the shoes and asymmetries.ParticipantsFifteen physically active women (average age of 23 years old, height of 1.64 m, and body mass of 63 kg).Main outcome measuresGround reaction forces.ResultsThe rebound shoe reduced the impact peak force and elicited slight asymmetries between the legs. The rebound shoe also showed a longer time to peak.ConclusionsThe rebound shoe tested reduced impact forces during jump-landing tasks, which is a potential application in training sessions and rehabilitation programs, requiring lower impact forces to the lower extremity. The effects of long-term use of these shoes still need to be investigated.     

Real-time modulation of visual feedback on human full-body movements in a virtual mirror: development and proof-of-concept

Background

Virtual reality (VR) provides interactive multimodal sensory stimuli and biofeedback, and can be a powerful tool for physical and cognitive rehabilitation. However, existing systems have generally not implemented realistic full-body avatars and/or a scaling of visual movement feedback. We developed a “virtual mirror” that displays a realistic full-body avatar that responds to full-body movements in all movement planes in real-time, and that allows for the scaling of visual feedback on movements in real-time. The primary objective of this proof-of-concept study was to assess the ability of healthy subjects to detect scaled feedback on trunk flexion movements.

Methods

The “virtual mirror” was developed by integrating motion capture, virtual reality and projection systems. A protocol was developed to provide both augmented and reduced feedback on trunk flexion movements while sitting and standing. The task required reliance on both visual and proprioceptive feedback. The ability to detect scaled feedback was assessed in healthy subjects (n = 10) using a two-alternative forced choice paradigm. Additionally, immersion in the VR environment and task adherence (flexion angles, velocity, and fluency) were assessed.

Results

The ability to detect scaled feedback could be modelled using a sigmoid curve with a high goodness of fit (R² range 89-98%). The point of subjective equivalence was not significantly different from 0 (i.e. not shifted), indicating an unbiased perception. The just noticeable difference was 0.035 ± 0.007, indicating that subjects were able to discriminate different scaling levels consistently. VR immersion was reported to be good, despite some perceived delays between movements and VR projections. Movement kinematic analysis confirmed task adherence.

Conclusions

The new “virtual mirror” extends existing VR systems for motor and pain rehabilitation by enabling the use of realistic full-body avatars and scaled feedback. Proof-of-concept was demonstrated for the assessment of body perception during active movement in healthy controls. The next step will be to apply this system to assessment of body perception disturbances in patients with chronic pain.     

A computer vision framework for finger-tapping evaluation in Parkinson's disease

ObjectivesThe rapid finger-tapping test (RFT) is an important method for clinical evaluation of movement disorders, including Parkinson's disease (PD). In clinical practice, the naked-eye evaluation of RFT results in a coarse judgment of symptom scores. We introduce a novel computer-vision (CV) method for quantification of tapping symptoms through motion analysis of index-fingers. The method is unique as it utilizes facial features to calibrate tapping amplitude for normalization of distance variation between the camera and subject.MethodsThe study involved 387 video footages of RFT recorded from 13 patients diagnosed with advanced PD. Tapping performance in these videos was rated by two clinicians between the symptom severity levels (‘0: normal’ to ‘3: severe’) using the unified Parkinson's disease rating scale motor examination of finger-tapping (UPDRS-FT). Another set of recordings in this study consisted of 84 videos of RFT recorded from 6 healthy controls. These videos were processed by a CV algorithm that tracks the index-finger motion between the video-frames to produce a tapping time-series. Different features were computed from this time series to estimate speed, amplitude, rhythm and fatigue in tapping. The features were trained in a support vector machine (1) to categorize the patient group between UPDRS-FT symptom severity levels, and (2) to discriminate between PD patients and healthy controls.ResultsA new representative feature of tapping rhythm, ‘cross-correlation between the normalized peaks’ showed strong Guttman correlation (μ₂ = −0.80) with the clinical ratings. The classification of tapping features using the support vector machine classifier and 10-fold cross validation categorized the patient samples between UPDRS-FT levels with an accuracy of 88%. The same classification scheme discriminated between RFT samples of healthy controls and PD patients with an accuracy of 95%.ConclusionThe work supports the feasibility of the approach, which is presumed suitable for PD monitoring in the home environment. The system offers advantages over other technologies (e.g. magnetic sensors, accelerometers, etc.) previously developed for objective assessment of tapping symptoms.     

“Artifactual fracture-subluxation” of cervical spine in computed tomography screening sans plain radiographs

Background contextComputed tomography (CT) has become the sole modality of screening for cervical injury in polytrauma because of the high sensitivity, speed, and convenience, thereby eliminating the need for plain radiographs.PurposeWe report two cases of misleading artifactual fracture-subluxation of cervical spine in CT, which could have resulted in needless treatment, and describe its characteristics.Study designCase report and review.MethodsTwo patients who were initially diagnosed with fracture-subluxation on screening CT cervical spine were later noted to have motion artifacts and were reviewed.ResultsThe artifactual nature of the supposed fracture-subluxation was unmasked by the soft-tissue findings of obscuration in sagittal reconstruction and duplication in axial images, along with the presence of double bony margins.ConclusionsMotion artifact in cervical CT screening can lead to a misdiagnosis of fracture subluxation. Duplication of soft tissue is highly suggestive of this motion artifact, and an additional single lateral plain radiograph may avert this pitfall.     

The use of polyurethane materials in the surgery of the spine: a review

Background contextThe spine contains intervertebral discs and the interspinous and longitudinal ligaments. These structures are elastomeric or viscoelastic in their mechanical properties and serve to allow and control the movement of the bony elements of the spine. The use of metallic or hard polymeric devices to replace the intervertebral discs and the creation of fusion masses to replace discs and/or vertebral bodies changes the load transfer characteristics of the spine and the range of motion of segments of the spine.PurposeThe purpose of the study was to survey the literature, regulatory information available on the Web, and industry-reported device development found on the Web to ascertain the usage and outcomes of the use of polyurethane polymers in the design and clinical use of devices for spine surgery.Study design/settingA systematic review of the available information from all sources concerning the subject materials' usage in spinal devices was conducted.MethodsA search of the peer-reviewed literature combining spinal surgery with polyurethane or specific types and trade names of medical polyurethanes was performed. Additionally, information available on the Food and Drug Administration Web site and for corporate Web sites was reviewed in an attempt to identify pertinent information.ResultsThe review captured devices that are in testing or have entered clinical practice that use elastomeric polyurethane polymers as disc replacements, dynamic stabilization of spinal movement, or motion limitation to relieve nerve root compression and pain and as complete a listing as possible of such devices that have been designed or tested but appear to no longer be pursued. This review summarizes the available information about the uses to which polyurethanes have been tested or are being used in spinal surgery.ConclusionsThe use of polyurethanes in medicine has expanded as modifications to the stability of the polymers in the physiological environment have been improved. The potential for the use of elastomeric materials to more closely match the mechanical properties of the structures being replaced and to maintain motion between spinal segments appears to hold promise. The published results from the use of the devices that are discussed show early success with these applications of elastomeric materials.     

Motion analysis in the pediatric laparoscopic surgery (PLS) simulator: validation and potential use in teaching and assessing surgical skills

Background

Construct validity for the pediatric laparoscopic surgery (PLS) simulator has been established through a scoring system based on time and precision. We describe the development and initial validation of motion analysis to teach and assess skills related to pediatric minimal access surgery (MAS).

Methods

Participants were asked to perform a standardized intracorporeal suturing task. They were classified as novices, intermediates, and experts. Motion in the four degrees of freedom available during traditional MAS (PITCH, YAW, ROLL and SURGE) was assessed using range, velocity, and acceleration.

Results

Analysis of motion allowed discrimination between the 75 participants according to level of expertise. The most discriminating motion parameter was the acceleration in performing the ROLL (pronation/supination) with values of 30 ± 27 for novices, 15 ± 5 for intermediates, and 3.7 ± 3 for experts (p < 0.001).

Conclusions

Tracking and analyzing the motion of instruments within the PLS simulator allow discrimination between novices, intermediates, and experts, thus establishing construct validity. Further development may establish motion analysis as a useful “real time” modality to teach and assess MAS skills.     

The association of equinus and primary genu recurvatum gait in cerebral palsy

Primary genu recurvatum (GR) is less investigated and data presenting the prevalence among patients with bilateral spastic cerebral palsy (BSCP) is lacking in the literature. Equinus is mentioned as one of the main underlying factors in GR, but its influence on the severity and onset type of GR is mainly unanswered, yet. Hence, the purpose of this retrospective study was to assess the prevalence of GR in a large sample size in children with BSCP and to investigate sagittal plane kinematics to evaluate the influence of equinus on different GR types using data of three-dimensional gait analysis. GR was defined as a knee hyperextension of more than one standard deviation of an age matched control group during stance phase in either one or both of the limbs. Primary GR was defined as a GR without having previous surgery regarding the lower extremity, no selective dorsal rhizotomy and/or interventions like botulinum toxin injection, shock wave therapy or serial casting during the last 6 months in the patient history. In a retrospective study 463 patients with BSCP (GMFCS Level I–III) received three-dimensional gait analysis and were scanned for the presence of primary GR. Finally, 37 patients (23 males, 14 females) matched the determined inclusion criteria and were therefore included for further analysis in this study. Out of those patients seven walked with orthoses or a walker and were excluded from further statistical comparison: Kinematics of the lower limbs were compared between patients having severe (knee hyperextension > 15°) and moderate (knee hyperextension 5–15°) GR and between patients showing an early (first half of stance phase) and a late (second half of stance phase) GR. Primary GR was present in 37 patients/52 limbs (prevalence 8.0/5.6%). Severe GR was associated with a decreased ankle dorsiflexion compared with moderate GR. Early GR showed an increased knee hyperextension compared to late GR. In conclusion GR is less frequent compared with crouch or stiff gait. Our findings support the importance of equinus as a major underlying factor in primary GR. In this context the influence of equinus seems to be more important in early GR.