Measuring Abnormality in High Dimensional Spaces with Applications in Biomechanical Gait Analysis.

Accurately measuring a subject's abnormality using high dimensional data can empower better outcomes research. Utilizing applications in instrumented gait analysis, this article demonstrates how using data that is inherently non-independent to measure overall abnormality may bias results. A methodology is then introduced to address this bias and accurately measure abnormality in high dimensional spaces. While this methodology is in line with previous literature, it differs in two major ways. Advantageously, it can be applied to datasets in which the number of observations is less than the number of features/variables, and it can be abstracted to practically any number of domains or dimensions. Initial results of these methods show that they can detect known, real-world differences in abnormality between subject groups where established measures could not. This methodology is made freely available via the abnormality R package on CRAN.

Improvements in gait speed and weight shift of persons with traumatic brain injury and vestibular dysfunction using a virtual reality computer-assisted rehabilitation environment.

Many people sustaining a traumatic brain injury experience vestibular pathology requiring physical therapy for treatment. This study measured improvements in gait speed and weight shift for subjects receiving vestibular physical therapy using a Computer-Assisted Rehabilitation Environment (CAREN). A 6-session CAREN, 6-session traditional vestibular therapy group was compared with a 12-session CAREN only (0 traditional sessions) therapy group. These two groups were compared to each other and with data from healthy controls performing similar tasks on the CAREN. Those participating in 12 CAREN sessions had greater improvements in gait speed (p=0.014) and weight shift scores (p<0.001) and demonstrated similar values achieved by a healthy control population.

A systematic literature review of the use and effectiveness of the Computer Assisted Rehabilitation Environment for research and rehabilitation as it relates to the wounded warrior.

BACKGROUND: Several U.S. military treatment and research facilities employ a Computer Assisted Rehabilitation Environment (CAREN) [Motek Medical BV, Amsterdam, The Netherlands] for research and rehabilitation of complex injuries exhibited by Wounded Warriors. There has been little scientific evidence of the effectiveness of this type of system for rehabilitation. OBJECTIVE: A systematic review of the literature was completed to determine what type of work has been performed on the CAREN and report findings of clinical significance. METHODS: Specific terms were searched on electronic databases to include journal articles, abstracts, and peer-reviewed conference proceedings related to the CAREN. RESULTS: Twenty-six publications were elicited that met our criteria. These were divided by their primary focus: rehabilitation, clinical research, and technical reports. DISCUSSION: Results from published articles have determined that the system is a capable tool for both assessment and rehabilitation, but little has currently been published, particularly on patient populations. CONCLUSION: More research needs to be performed to evaluate its effectiveness as a rehabilitation tool compared to other rehabilitation methods. It is expected that a system, such as the CAREN, will challenge patients multifactorially (e.g. physically and cognitively) and provide biofeedback while decreasing rehabilitation time and increasing effectiveness of treatment.

Do patients with bone bridge amputations have improved gait compared with patients with traditional amputations?

BACKGROUND: Two surgical techniques for performing a transtibial amputation include a traditional approach and a bone bridge approach. To date, there is no conclusive evidence of superiority of either technique in terms of temporal-spatial, kinetic, and mechanical work parameters. QUESTIONS/PURPOSES: We sought to compare instrumented three-dimensional gait parameters and mechanical work measurements of patients who had undergone a traditional or bone bridge amputation at the transtibial level. Residual limb length and its effect on those functional outcomes was a secondary interest irrespective of amputation type. METHODS: This retrospective comparative study included 14 active-duty military men with a mean age of 25 years (range, 20-28 years). Comparisons were made between seven patients with traditional and seven patients with bone bridge amputations at the transtibial level. The patients walked at self-selected and fast paces while three-dimensional gait analysis data were collected and comparisons were made between patients with the two amputation types as well as by length of the residual limb. RESULTS: With the numbers available, we observed no differences between the two surgical groups at either speed for the temporal-spatial parameters or mechanical work metrics. However, the bone bridge group did demonstrate greater rolloff vertical ground reaction force during the fast walking condition with a median 1.02% of body weight compared with 0.94% (p = 0.046), which suggests a more stable platform in terminal stance. When the two groups were combined into one to test the effect of residual limb length, the linear regression resulted in an R(2) value of 0.419 (p = 0.012), in which patients with longer residual limbs had improved F3 force values during self-selected walking. CONCLUSIONS: Overall, limited functional differences were found between the two groups in this small pilot study, so a superior surgical technique could not be determined; whereas our limited sample size prevents a firm conclusion of no difference, our data can be considered hypothesis-generating for future, larger studies. Although some evidence indicated that patients with a bone bridge have improved loading at higher speeds, a regression of all patients walking at self-selected speed indicates that as residual limb length increases, loading increases regardless of amputation type. Thus, our data suggest it is important to preserve residual limb length to allow for improved loading in terminal stance.

Method for evoking a trip-like response using a treadmill-based perturbation during locomotion.

Because trip-related falls account for a significant proportion of falls by patients with amputations and older adults, the ability to repeatedly and reliably simulate a trip or evoke a trip-like response in a laboratory setting has potential utility as a tool to assess trip-related fall risk and as a training tool to reduce fall risk. This paper describes a treadmill-based method for delivering postural perturbations during locomotion to evoke a trip-like response and serve as a surrogate for an overground trip. Subjects walked at a normalized velocity in a Computer Assisted Rehabilitation Environment (CAREN). During single-limb stance, the treadmill belt speed was rapidly changed, thereby requiring the subject to perform a compensatory stepping response to avoid falling. Peak trunk flexion angle and peak trunk flexion velocity during the initial compensatory step following the perturbation were smaller for responses associated with recoveries compared to those associated with falls. These key fall prediction variables were consistent with the outcomes observed for laboratory-induced trips of older adults. This perturbation technique also demonstrated that this method of repeated but randomly delivered perturbations can evoke consistent, within-subject responses.