Significance of orientation and determination of cummulative damage measures during cyclic testing of human thoracolumbar spine.

Determining the mechanical properties of the spine is a significant step in understanding the behavior of the spine under normal conditions. Although a limited amount of data for cyclic loading is currently available, the tests are not completely documented and the loads, spine segment positioning, and frequency are not representative of those typically found during normal activities. The purpose of this study is to develop an understanding of the relationship between loads and the development of fatigue failure in thoracolumbar motion segments. Motion segments separated from human cadaveric spine were tested in two series. Compression series applied a pure compression load quasi-statically in the neutral position. The load was increased and the specimen was observed to determine failure. Motion segments were also tested without orientation (axially aligned). The results from the tests show that mechanical properties of the disc depend on the orientation of the motion segments at neutral angle. Results also suggest that energy dissipation could be potentially a good damage measure unlike creep

Monitoring Location-Specific Physical Activity via Integration of Accelerometry and Geotechnology Within Patients With or At Risk of Diabetic Foot Ulcers: A Technological Report

Objective: Physical activity variability is a risk factor for diabetic foot ulcers (DFU). Geographic context may influence variability. This study developed initial methods for monitoring location-specific physical activity in this population. Secondarily, preliminary comparisons in location-specific physical activity were made between patients at risk versus patients with active DFU.Methods: Five at-risk and 5 actively ulcerated patients were monitored continuously for 72 hours with physical activity and GPS monitors. A custom algorithm time synchronized the 2 devices’ data.Results: On average for all 10 subjects, 1.5 ± 2.1% of activity lacked a corresponding GPS location. 80 ± 11% of self-reported activity events per subject had a GPS identified location. The GPS identified locations were in agreement with the self-reported locations 98 ± 6% of the time. DFU participants’ weight-bearing activity was 188% higher at home than away from home. At-risk participants showed similar weight-bearing activity at home as active DFU participants, however, at-risk participants had 132% more weight-bearing activity away-from-home.Conclusions: Objectively monitoring location-specific physical activity proved feasible. Future studies using such methodology may enhance understanding of pathomechanics and treatment of DFU

Structural integrity of custom-designed additive manufactured prosthetic sockets compared to traditional sockets

Over the past decades, the number of patients with lower extremity amputation increased world-wide. The increasing rate of patients, particularly in developing countries, has led to limited access to clinics and services for prosthetic and orthotic care. Additive manufacturing has rapidly evolved over the last decade and is opening new possibilities for prosthetics and orthotics. 3D printed prosthetic sockets are a promising solution to reduce access- or cost-related barriers to prosthesis use since 3D printed prosthetic sockets can be manufactured at an affordable cost and quickly delivered to patients. We sought to compare the ultimate strength of 3D printed sockets made of different filaments (polyethylene terephthalate glycol, polycarbonate, and co-polymer polypropylene) with that of traditionally fabricated sockets (laminated composite sockets and thermoplastic sockets) and to examine whether the strength of 3D printed sockets could be improved through iterative design changes focused on reinforcing the distal end of the socket. All sockets were mechanically tested in accordance with ISO 10328 standards. Although the strength of all of the 3D printed sockets was weaker than that of laminated composite sockets, design modifications to reinforce the distal end improved the strength of 3D printed sockets made of polycarbonate and polypropylene (but not polyethylene terephthalate glycol), resulting in ultimate strengths and stiffnesses that were comparable to the traditionally fabricated thermoplastic socket. In addition, our results demonstrated that socket failure occurred mainly at the distal end regardless of material type. The strength of some 3D printed sockets under limited testing conditions showed promise to be used for clinical purpose, especially when the socket was reinforced with distal struts

Segmenting human trajectory data by movement states while addressing signal loss and signal noise

This paper considers the problem of partitioning an individual GPStrajectory data into homogeneous, meaningful segments such asstops and trips. Signal loss and signal noise are highly prevalent inhuman trajectory data, and it is challenging to deal with uncertaintiesin segmentation algorithms. We propose a new trajectorysegmentation algorithm that detects stop segments in a noiserobustmanner from GPS data with time gaps. The algorithm consistsof three steps that impute time gaps, split data into basesegments and estimate states over a base segment. The statedependentpath interpolation was proposed as a framework forgap imputation to deal with locational and temporal uncertaintiesassociated with signal loss. A spatiotemporal clustering-based trajectorysegmentation was proposed to detect spatiotemporal clustersof any shape regardless of density to cut a trajectory intointernally similar base segments. Fuzzy inference was employed todeal with borderline cases in determining states over base segmentsbased on input features. The proposed algorithm wasapplied to detect stop/move episodes from raw GPS trajectoriesthat were collected from 20 urban and 19 suburban participants.Sensitivity analysis was conducted to guide the choice of parameterssuch as the temporal and spatial definitions of a stop.Experimentation results show that the proposed method correctlyidentified 92% of stop/move episodes, and correctly estimated 98%of episode duration. This study indicates that a sequence of statedependentgap imputation, clustering-based data segmentationand fuzzy-set-based state estimation can satisfactorily deal withuncertainty in processing human GPS trajectory data

A Growing Troubling Triad: Diabetes, Aging, and Falls

There is a significant and troubling link between diabetes (DM) and falls in the elderly. Individuals with DM are prone to fall for reasons such as decreased sensorimotor function, musculoskeletal/neuromuscular deficits, foot and body pain, pharmacological complications, and specialty (offloading) footwear devices. Additionally, there is some concern that DM patients are prone to have more severe problems with falls than non-DM individuals. Fractures, poorer rehabilitation, and increased number of falls are all concerns. Fortunately, efforts to mitigate falls by DM patients show promise. A number of studies have shown that balance, strength, and gait training may be utilized to successfully reduce fall risk in this population. Furthermore, new technologies such as virtual reality proprioceptive training may be able to provide this reduced risk within a safe training environment

Effects of hallux valgus surgery on balance and gait in middle aged and older adults

Hallux valgus is associated with balance deficits, and has been implicated as an independent risk factor for falls in older adults. However, it is unknown what effect hallux valgus surgery has on static and dynamic (i.e., while walking) balance in older adults. We enrolled 13 middle-aged and older aged adults (mean age 54.3 ± 12.7 years, range 47 to 70) who underwent isolated hallux valgus surgery and followed them for 12 months. Preoperative and postoperative gait and balance performance was assessed using non-invasive body worn sensors with standardized and validated testing protocols. Visual analog scale (VAS) for pain and radiographic angles were also assessed. All subjects reported improvements in pain (VAS mean change -38.3 ± 10.3 mm), and all subjects demonstrated improvements in their hallux valgus angles and first/second intermetatarsal angles (mean change 16.3 ± 8.8°, and 5.5 ± 3.0°, respectively). While standing in full tandem, center of mass (COM) sway was improved upon by 59% at 1 year postoperative (p \u3c .05, paired t-test). While most gait parameters demonstrated little change postoperatively, patients tended to spend less time in double support (p = .08, paired t-test), while gait variability increased by 55% (p = .03, paired t-test) and medial-lateral sway while walking increased by 43% (p = .08, paired t-test) 12 months postoperatively. Balance improved after hallux valgus surgery in our population, particularly when subjects were forced to rely on their operative foot for support (e.g., full tandem). Patients also seemed to walk with greater variability in stride velocity and with greater medial-lateral sway postoperatively, suggesting perhaps increased ambulatory confidence after successful hallux valgus surgery

A Growing Troubling Triad: Diabetes, Aging, and Falls

There is a significant and troubling link between diabetes (DM) and falls in the elderly. Individuals with DM are prone to fall for reasons such as decreased sensorimotor function, musculoskeletal/neuromuscular deficits, foot and body pain, pharmacological complications, and specialty (offloading) footwear devices. Additionally, there is some concern that DM patients are prone to have more severe problems with falls than non-DM individuals. Fractures, poorer rehabilitation, and increased number of falls are all concerns. Fortunately, efforts to mitigate falls by DM patients show promise. A number of studies have shown that balance, strength, and gait training may be utilized to successfully reduce fall risk in this population. Furthermore, new technologies such as virtual reality proprioceptive training may be able to provide this reduced risk within a safe training environment

An immediate effect of custom-made ankle foot orthoses on postural stability in older adults

AbstractBackgroundFoot and ankle problems are highly prevalent fall risks in the elderly. Ankle foot orthoses designed to stabilize the foot and ankles have been studied within specific patient groups, but their efficacy with a less restrictive elderly population is unknown. This study investigated if custom-made ankle foot orthoses improve postural stability in older adults.MethodsThirty ambulatory older adults averaged 73 (standard deviation=6.5) years completed Romberg's balance (eyes-open/eyes-closed), functional reach, and Timed Up and Go tests while wearing validated kinematic sensors. Each test was completed in standardized shoes with and without bilateral orthoses. Additionally, barefoot trials were conducted for the Romberg's and functional reach tests.FindingsCompared to the barefoot and ‘shoes alone’ conditions, the orthoses reduced center of mass sway on average by 49.0% (P=0.087) and 40.7% (P=0.005) during eyes-open balance trials. The reduction was amplified during the eyes-closed trials with average reductions of 65.9% (P=0.000) and 47.8% (P=0.004), compared to barefoot and ‘shoes alone’ conditions. The orthoses did not limit functional reach distance nor timed-up and go completion times. However, the medial-lateral postural coordination while reaching was improved significantly with orthoses compared to barefoot (14.3%; P=0.030) and ‘shoes alone’ (13.5%; P=0.039) conditions.InterpretationAnkle foot orthoses reduced postural sway and improved lower extremity coordination in the elderly participants without limiting their ability to perform a standard activity of daily living. Additional studies are required to determine if these benefits are retained and subsequently translate into fewer falls