Age-related differences in dynamic balance control during stair descent and effect of varying step geometry.

The incidence of stairway falls and related injuries remains persistently high; however, the risk of stair injuries could be reduced through improved stairway design. The current study investigated dynamic balance control during stair descent and the effects of varying the step geometry. Data were collected from 20 healthy young and 20 older adults as they descended three staircases (riser heights of 7, 7.5 and 8 inches (178, 190 and 203 mm, respectively)). At each riser height, the tread run length was varied between 8 and 14 inches (203 mm and 356 mm) in one-inch (25 mm) increments. Kinematic data provided measures of segmental and whole-body dynamic control. Results demonstrated that older adults had greater lateral tilt of the upper body than young adults, but actually had larger margins of stability than the young in the antero-posterior direction as a result of their slower cadence. Nonetheless, for both age groups, the longer run lengths were found to provide the largest margins of stability. In addition, increase in run length and decrease in riser height tended to reduce forward upper body tilt. These results help to explain the underlying biomechanical factors associated with increased risk of falls and the relationship with step geometry. Considering the importance of stair ambulation in maintaining independence and activity in the community, this study highlights the definite need for safer stair design standards to minimize the risk of falls and increase stair safety across the lifespan.

Acceptability of a wearable hand hygiene device with monitoring capabilities.

Transmisssion of infection within healthcare institutions is a significant threat to patients and staff. One of the most effective means of prevention is good hand hygiene. A research team at Toronto Rehabilitation Institute, Ontario, Canada, developed a wearable hand disinfection system with monitoring capabilities to enhance hand wash frequency. We present the findingsof the first phase of a larger study addressing the hypothesis that an electronic hand hygiene system with monitoring and reminding propertieswill increase hand hygiene compliance. This first phase focused on the acceptability and usability of the wearable electronic hand wash device ina clinical environment. The feedback from healthcare staff to the first prototype has provided evidence for the research team to continue with the development of this technology.

The use of artificial intelligence in the design of an intelligent cognitive orthosis for people with dementia.

Dementia often reduces a person's ability to perform activities of daily living because he or she becomes confused and cannot remember the sequence of steps to perform. The current solution is to have a caregiver continually supervise and assist the person using verbal reminders or cues. This loss of privacy and increased dependency may cause the affected person to become embarrassed and agitated. We propose that this situation might be improved by using a computerized device that monitors progress and provides the reminders needed. The COACH is a first prototype of such a device. It uses artificial intelligence to observe a user, learn from his or her actions, and issue prerecorded cues of varying detail. The device was developed using a personal computer and a video camera that unobtrusively tracked the user. Preliminary testing with subjects who simulated confused behavior as they washed their hands showed that the device was performing its functions with an efficacy of approximately 95%. More extensive clinical testing and evaluation has begun, and the results will be reported in future publications.

The efficacy of head immobilization techniques during simulated vehicle motion.

STUDY DESIGN: Laboratory experiment. OBJECTIVE: To compare the efficacy of different head immobilization techniques during motion simulating ambulance transport. BACKGROUND: A significant number of neurologic injuries associated with cervical spine fractures arise or are aggravated during emergency extrication or patient transport. Previous studies have not addressed the effect of head immobilization on the passive motion that could occur across the neck during transport. METHODS: Three different head-immobilization methods were compared in six healthy young adults by using a computer-controlled moving platform to simulate the swaying and jarring movements that can occur during ambulance transport. In all tests, the trunk was secured by means of a commonly used "criss-cross" strapping technique. Efficacy of head immobilization was evaluated using measures of head motion and neck rotation. RESULTS: None of the three immobilization techniques was successful in eliminating head motion or neck rotation. Movement of the trunk contributed substantially to the lateral bending that occurred across the neck. A new product involving the placement of wedges underneath the head provided some small, but statistically significant improvements in fixation of the head to the fracture board; however, there was no improvement in terms of the relative motion occurring across the neck. CONCLUSIONS: Somewhat improved fixation of the head to the fracture board can be achieved by placing wedges under the head; however, the benefits of any fixation method, in terms of cervical spine immobilization, are likely to be limited unless the motion of the trunk is also controlled effectively. Future research and development should address techniques to better control head and trunk motion.

Mechanical response of the lumbar spine to seated postural loads.

STUDY DESIGN: In vitro force and deformation measurements formed the basis for determinate, quasistatic analysis of principal forces in the seated lumbar spine. OBJECTIVES: To explore the relationship between seated postures and the mechanical response in component tissues of lumbar intervertebral joints. SUMMARY OF BACKGROUND DATA: Despite the high prevalence of low back pain syndrome, the precise mechanisms relating specific mechanical loads to spinal degeneration are not well understood. Simultaneous, time-dependent measurement of anterior column forces and articular facet forces has not been presented previously. consequently, a determinate analysis of principal component forces has not been possible. METHODS: Twelve lumbar spines (L1-S1) were subjected to constant loading conditions while in flexed and extended seated postures. Time-dependent forces were measured in the anterior column at the L4 and L5 superior endplates and in the four facets of the L3-L4 and L4-L5 motion segments. A quasi-static analysis of sagittal plane forces was used to compute the remaining principal joint forces, including ligament, disc shear, and facet impingement forces. RESULTS: Component forces changed under static loading in both postures. There were significant differences between the mechanical responses of the two postures. Although the vertical creep displacement was greater in the extended seated posture (3.22 mm versus 2.11 mm), the escalation of forces was more severe in the flexed posture. CONCLUSIONS: The results suggest a mechanism of force balancing in lordotic postures under static loads, whereas flexed postures produce large increases to the tensile forces in the region of the posterior anulus.

An interface to enhance mobility for people with hemispatial neglect.

The objective was to develop and test a control interface to enable people with hemispatial neglect to maneuver a powered wheelchair with increased attention to their environment. A single case study was conducted using a female (aged 72 years) who had a right cerebro vascular accident five years earlier. She drove a powered wheelchair through 20 different test courses (mazes) while a computer recorded frequency of looking to the left (left checks) and an observer recorded visual targets missed and wheelchair collisions with walls and obstacles. The Mann-Whitney test was used to determine significant differences in left checks, left collisions, right collisions, and percent left checks targets missed between baseline and strategy phases. With the interface strategy, the subject significantly increased the number of left checks and missed fewer left targets in the test course. These results indicate that a powered-wheelchair control interface shows promise in enabling people with mild hemispatial neglect to maneuver a powered chair with greater environmental awareness and ease.

In vivo measurement of lumbar spinal creep in two seated postures using magnetic resonance imaging.

STUDY DESIGN: A magnetic resonance imaging technique was developed to measure creep in the lumbar spine in different seated postures. Owing to the fixed size and horizontal orientation constraints of the magnetic resonance imaging system bore, gravitational force was simulated in the horizontal plane while the subject assumed each of two near-seated postures: 1) flexed lumbar, and 2) extended lumbar. OBJECTIVES: One experimental subject was used to determine the feasibility of this technique designed to correlate spinal creep with different seated postures. SUMMARY OF BACKGROUND DATA: Although epidemiologic and pathologic studies have linked the seated posture with low back pain and disc degeneration, few in vivo studies have explored the mechanical response of the lumbar spine to seated postures. METHODS: Creep displacement of four lumbar discs (L3-S1) was measured from unloaded and loaded scans separated by 30 minutes of constant loading. Forty-eight images were measured from three trials in each posture, four sagittal slices per trial. RESULTS: Creep while in an extended posture (3.58 mm) was greater than creep while in a flexed posture (2.92 mm). System resolution was 0.78 mm. CONCLUSION: This technique can be used to discern between creep displacements in different postures.

The impact of new lifting technology in long term care: a pilot study.

1. The researchers conducted a pilot study to test a new lifting system developed with the assistance of nurses. 2. The lift system consists of a portable battery operated power unit that the nurse carries to the bedside and attaches to an overhead track; the ability to share the portable power unit among several track locations is economical. 3. The new lifting system was found to reduce the number of staff necessary to execute patient lifts. This staff saving amounted to 50% of one full time equivalent person per nursing unit. 4. Nurses perceived that less effort was required using the new lifting system compared to a conventional floor model wheeled lifting device.

Bladder volume estimation in the elderly using a portable ultrasound-based measurement device.

We assessed the accuracy and ease of use of the BladderScan (BVI 2000) portable ultrasound-based bladder volume measurement device in a geriatric outpatient population. The Geriatric Continence Clinic nurse and physician each made 73 measurements on 36 subjects. Although the correlation coefficients between the true and ultrasound measurements were highly significant the mean differences were significantly different from zero. We suggest that, rather than considering the correlation coefficient, the accuracy required of the device should be described by a function of estimated versus true bladder volume. This function should vary depending on each particular decision-making process in which the estimate of volume is to be used. This instrument automatically estimates bladder volume once the user has completed the image creation and selection part of the process. The users in this study had difficulties with this imaging process. Possible ways in which the device's automated signal processing and volume calculation algorithms could be improved became evident during this study and are discussed.

Functional biomechanics of the spine.

The exact nature of the mechanisms at work during movement of the human spine are not well understood, nor well defined. The spine supports the torso against loads and allows freedom of motion, within physiologic limits, at the same time. A great deal of information characterizing various attributes of the spine is available. Research has provided values for flexural stiffness, axial compliance, range of motion under various loading modalities, and considerably more. This study will focus not on isolated topics, but rather serve as a broad introduction to the behavior of the spine as a whole.

Design of an intervertebral disc prosthesis.

This article presents criteria for the design of a lumbar intervertebral disc prosthesis that take into consideration issues of endurance, materials behavior, geometry, kinetics, motion constraints, fixation to bone, and safety. The criteria and design philosophies discussed are generally applicable in the synthesis of any new implant system. Specifications of the design of a disc prosthesis are presented along with an evaluation of the design based on some of the preliminary test data.

An evaluation of computer aided design of below-knee prosthetic sockets.

Forty-eight below-knee amputees compared sockets designed using CANFIT computer aided design (CAD) software with sockets designed using conventional methods. Each subject was fitted by one prosthetist who used conventional techniques and one who used the CANFIT system to design the socket. Prosthetists alternated design methods for each new subject. The prosthetist using the conventional techniques was allowed up to 2 design attempts and the prosthetist using the CANFIT system was allowed up to 5 design attempts. After 2 design attempts with each method 21% of the subjects preferred the CANFIT design socket. Following up to 5 attempts 54% preferred the CANFIT designed socket. A jury of experts made an assessment of the CANFIT system and of CAD in prosthetics. The jury did not think that the version of the system tested was cost effective but that at the rate that it was improving it would become such within 3 to 5 years. The jury noted that, as well as monetary benefits, CAD presents the possibility of benefits in other areas such as research and teaching. A number of specific suggestions regarding the use and development of CAD in prosthetics were also made.

Computer-aided design and computer-aided manufacturing (CAD/CAM) in prosthetics.

Computer-aided design and computer-aided manufacturing (CAD/CAM) systems for the design and manufacture of limb prostheses have recently become commercially available. However, rigorous evaluations of these systems have not been performed to determine whether they produce sockets that fit as well as or better than sockets made using conventional design methods. A controlled evaluation protocol, in which computer-designed sockets are compared with conventionally designed sockets, has been developed and pilot tested at the authors' facility. A full trial of one of the commercially available systems for transtibial sockets is currently in progress. In preliminary findings, the CAD/CAM socket was preferred by one-half of the first 20 subjects. During the course of this trial, it was noted that the CAD/CAM technique seems to be better suited to some prosthetists than others.

Impact attenuation of floor coverings in simulated falling accidents.

An experimental study was performed to assess to what extent the magnitudes of the impact forces generated in human falling accidents are affected by the nature of the floor covering. Peak decelerations were measured for impacts at the hip and at the hand, using a simple inverted-pendulum anthropomorphic fall simulator. Thirteen different floor coverings were tested, including five hard surfaces and four types of carpet, with and without underpad. It was found that floor coverings can differ significantly in terms of the peak impact force occurring during a fall. For hip impacts, the mean differences between the different floorings ranged up to 23%, with the padded carpets providing the best impact attenuation. In hand impacts, the impact forces were found to be relatively independent of the type of floor covering.

Aging and postural control. A comparison of spontaneous- and induced-sway balance tests.

Two different balance testing methods were compared: (1) measurement of spontaneous postural sway during quiet standing, and (2) measurement of induced postural sway in response to an applied postural perturbation. Eyes-open tests were performed in 64 healthy young and elderly adults and in five elderly subjects with a history of falling. In both balance tests, the sway was defined in terms of the displacement of the center of pressure on the feet. Spontaneous sway was quantified using a number of different amplitude- and frequency-based parameters. Induced sway was measured in response to anterior-posterior acceleration of a platform on which the subject stood. The induced-sway test was specially designed to be safe and nonthreatening for elderly subjects; thus, the platform perturbation was confined to small accelerations and a gentle pseudorandom motion was used. To derive a measure of postural stability, the data from this test were fitted with a model that was then used to predict the response to sudden (transient) perturbations, thereby simulating the response in actual falls. Although both induced- and spontaneous-sway measures demonstrated significant aging-related decreases in stability, the differences were more pronounced for the induced-sway data. Conversely, some of the spontaneous-sway measures were much more successful in distinguishing the fallers from the nonfallers. There was a significant correlation between induced-sway and certain spontaneous-sway measures in the normal young adults; however, in the elderly normals and fallers, the data from the two types of balance tests either showed no correlation or, for certain spontaneous-sway measures, tended to show an inverse relationship.

Oxybutynin chloride for geriatric urinary dysfunction: a double-blind placebo-controlled study.

Twenty-four incontinent elderly institutionalized subjects with detrusor instability participated in a double-blind placebo-controlled trial of oxybutynin chloride. Patients were randomly assigned to oral oxybutynin 5 mg or placebo twice daily. Administration continued for 8 days; a 6-day washout period was followed by the alternative treatment. Incontinence was recorded using a bedside electronic monitor. Four subjects withdrew because of side-effects before completing the trial. There were no clinically significant differences between the oxybutynin and placebo treatments. Both groups experienced side-effects, of which dry mouth was the commonest. Thus, oxybutynin does not appear to be more effective than placebo for the treatment of incontinence in the presence of detrusor instability in elderly institutionalized people.

Migration, attachment, and orientation of human gingival fibroblasts to root slices, naked and porous-surfaced titanium alloy discs, and Zircalloy 2 discs in vitro.

Cell migration, attachment, and orientation of cultured human gingival fibroblasts (HGF) were measured in relation to four types of specimens: Ti-6Al-4V alloy discs with either ground surfaces or porous structured surfaces, and Zr alloy discs (Zircalloy 2) with either ground surfaces or surfaces modified by being heated to form a thicker oxide cover. Surface-demineralized and non-demineralized root slices were used as controls. Initial cell attachment was measured by means of a 51Cr assay, and cell attachment and orientation following migration by an assay that measures development of the resulting refractile material in relation to the specimen. No significant difference between initial cell attachment to Ti alloy and control demineralized root slices could be detected after one hr using the 51Cr assay. However, with the second assay, cell attachment and orientation at three, seven, 10, and 14 days were significantly higher in relation to surface-demineralized root slices than to all of the metal discs and the non-demineralized root slices. While cell attachment to the surface-ground Ti alloy discs appeared to be higher than that to the porous-surfaced Ti alloy discs at three days and seven days, cell orientation to the porous-surfaced Ti alloy discs and the non-demineralized root slices at days 7, 10, and 14 was greater than that to all of the other metal discs. These data suggest that surface geometry could affect attachment and orientation of cells in vitro.