Hand/wrist disorders among sign language communicators.

The study assessed the frequency of self-reported hand/wrist problems among sign language communicators, including interpreters, deaf or hard-of-hearing individuals, and educators. Comparisons were also made between sign language communicators and the general population regarding the frequency of medically diagnosed carpal tunnel syndrome. A survey was mailed to attendees of a national conference that focused on the quality of postsecondary educational opportunities for students with hearing deficits. Fifty-nine percent of 184 respondents reported experiencing hand/wrist problems. Twenty-six percent reported experiencing hand/wrist problems severe enough to limit the ability to work, and 18% reported a medical diagnosis of wrist tendinitis, carpal tunnel syndrome, or both. The frequency of self-reported, medically diagnosed carpal tunnel syndrome for the surveyed sign language communicators was five times the rate experienced by working Americans between ages 18 and 60 years (Tanaka, Wild, Seigman, Halperin, Behrens, & Putz-Anderson, 1995). The study supports increased emphasis on and availability of hand/wrist disorder risk reduction programs for sign language users.

An experimental study of airbag impact to the orbit using an instrumented Hybrid III headform.

This paper provides the results from an experimental study intended to assess airbag impact to the orbit. Twenty-seven airbags were deployed onto an instrumented Hybrid III headform. Seven different types of airbags were used that included tethered and nontethered, light to heavy nylon weaves, and different coating types. The airbags were deployed via a pneumatic deployment system. Seven individual force transducers, each having a 2.25 cm2 contact area, were placed on the right orbital region to evaluate the force patterns. The midpoint of the two ocular regions of the headform was positioned 12.5 cm above and 15.0 cm away from the center of the airbag, a position determined from previous airbag deployments to yield the highest leading edge velocity. The average maximum force per sensor ranged from 15.4 N to 63.6 N, and peak pressure ranged from 68 kPa to 282 kPa. The upper center of the orbit presented the highest values while the center of the orbit recorded the lowest values, a comparison that was proven to be statistically significant. For this configuration, the maximum force on the ocular region was found to be independent of the presence of a tether or the maximum internal airbag pressure.

Airbag-induced eye injuries: experiments with in situ cadaver eyes.

In an attempt to investigate eye injuries from airbags, a set of experiments was performed that involved the deployment of several types of airbags onto thirteen unembalmed, previously frozen cadaver heads. The airbags differed in the material, coating, presence of a tether, and folding pattern, and were deployed via a pneumatic deployment system. The eyes were impacted in situ after being repressureized with saline injected through a 30-gauge needle. Injury determination was achieved by ophthalmic ultrasound imaging, staining with fluorescein dye, and dissection. All twenty-six eyes revealed detached retinas, as shown by the ultrasound, before impact as a result of decaying tissue and the freezing process. High speed video and film were used to capture the events. The impact velocities of the airbags were recorded from the digitized film at the first contact location with the eye and ranged from 30 m/s to 66 m/s. Eyeglasses were placed on four of the specimens, and the presence of eyeglasses seemed to provide protection to the eye because of the lack of contact between the airbag and ocular region. Minimal ocular damage was recorded for all experiments.

Production of spiral fractures in human cadaver long bones by use of a simple torsion machine.

A simple machine was developed so that long bones could be torqued to failure in order to estimate applied moment and study the resulting spiral fracture pattern. Detailed study of the fragments enabled the postulation of an orderly manner of fracture propagation. Twenty-seven embalmed human cadaver femurs were studied. The machine held one end of the bone in a fixed vise and the other in a rotating vise. Spring scales were used to apply force to a bar connected to the rotating vise which allowed for a crude estimation of torsional moment. Male femurs (72.8 yrs old sigma = 11.4) fractured at a mean torque of 106.7 N-m (sigma = 23.8), while female femurs (78.0 yrs old sigma = 6.7) failed at a mean torque of 96.7 N-m (sigma = 39.4). There were no statistically significant differences between the ages (p = 0.20) or the torsional moments at fracture (p = 0.41) for the male and female femurs. Given the similarities in this study population, an eye was turned towards anthropomorphic measurements in order to determine factors that might be indicative of bone strength. Several measurements were made on the fragments especially in the midshaft region. These included six cortex thicknesses, bone depth, width and circumference. Simple statistical analyses were performed.

Fractures of experimentally traumatized embalmed versus unembalmed cadaver legs.

Intact legs from six geriatric cadavers were fractured in a self-controlled study aimed at documenting the effects of embalming on both the soft and hard tissues of cadaver specimens subjected to biomechanical impact research. Upon bequeathal, one leg was removed and frozen while the other remained with the cadaver for embalming. The embalmed legs were amputated later and pre-test radiographs were made. For testing, a rod was inserted in the upright leg such that simulated upper body mass could be applied. A 50 kg cart propelled by a pneumatic accelerator to 7.5 m/s struck the anterior leg midway between the knee and ankle. The cart was headed by an instrumented steel pipe (4.75 cm dia.) coupled to a transducer which relayed impact force data to a Hewlett Packard 3562 A signal analyzer. Testing was captured on standard VHS video (30 frames/s) and 16 mm Color High Speed Film (1,000 frames/s). Post-test analyses included radiographs and thorough dissection. Peak forces were comparable for matched pairs. The unembalmed legs showed greater soft tissue damage (muscle and skin) but generally less bone fragmentation than their embalmed counterparts. Neurovascular components were virtually unharmed in most legs.

Airbag-induced eye injuries: a report of 25 cases.

OBJECTIVE: To acquire a better understanding of airbag-induced eye injuries, 25 cases are reviewed and an attempt is made to identify the causal mechanisms associated with each injury. DESIGN AND METHODS: The National Highway Traffic Safety Administration's National Accident Sampling System for the years 1984-1994 was accessed to identify automobile accidents that included airbag deployment and injury to the ocular region. The search provided 25 such cases with detailed studies of the accident scene and medical records of the injuries. The cases were comprehensively reviewed to determine the casual mechanisms associated with each group of injuries. RESULTS: The study determined that the injuries range from mild corneal abrasions to retinal detachment. Causation for each injury was determined and is detailed. The injuries were grouped according to location within the ocular region, and the distribution is shown. CONCLUSIONS: Most of the injuries were induced by impact with the fully deployed airbag, but the more severe ocular trauma resulted from the actively deploying airbag striking the occupant. Thus, ocular trauma from airbags can occur in very minor impacts. Additionally, the left eye seemed more vulnerable to injury than the right. Nontethered airbags have greater inflation distances that tend to increase the probability of injury. External parameters that may also increase the severity of eye injury include an unfastened seat belt, sitting too close to the steering wheel, or wearing glasses.