shapecoder: a new method for visual quantification of body mass index in young children.

BACKGROUND: Few tools exist to quantify body mass index visually. OBJECTIVE: To examine the inter-rater reliability and validity (sensitivity and specificity for overweight/obesity and obesity) of a three-dimensional visual rating system to quantify body mass index (BMI) in young children. METHODS: Children (n = 242, mean age 5.9 years, 50.0% male; 40.5% overweight/ obese) participated in a videotaped protocol and weight and height were measured. Research staff applied a novel three-dimensional computer-based figure rating system (shapecoder) to the child's videotaped image. Inter-rater reliability was calculated, as well as correlation with measured body mass index (BMI) and sensitivity, specificity, positive predictive value and negative predictive value for overweight/obesity and obesity. RESULTS: Inter-rater reliability was excellent (intraclass correlation coefficient = 0.98). The correlation of shapecoder-generated BMI with measured BMI was 0.89. For overweight/obesity, the sensitivity, specificity, positive predictive value and negative predictive value were 62%, 97%, 94% and 79% respectively. For obesity, these values were 65%, 99%, 97% and 92% respectively. CONCLUSION: shapecoder provides a method to quantify child BMI from video images with high inter-rater reliability, fair sensitivity and good specificity for overweight/obesity and obesity. The approach offers an improvement over existing two-dimensional rating scales for BMI.

A method for developing biomechanical response corridors based on principal component analysis.

The standard method for specifying target responses for human surrogates, such as crash test dummies and human computational models, involves developing a corridor based on the distribution of a set of empirical mechanical responses. These responses are commonly normalized to account for the effects of subject body shape, size, and mass on impact response. Limitations of this method arise from the normalization techniques, which are based on the assumptions that human geometry linearly scales with size and in some cases, on simple mechanical models. To address these limitations, a new method was developed for corridor generation that applies principal component (PC) analysis to align response histories. Rather than use normalization techniques to account for the effects of subject size on impact response, linear regression models are used to model the relationship between PC features and subject characteristics. Corridors are generated using Monte Carlo simulation based on estimated distributions of PC features for each PC. This method is applied to pelvis impact force data from a recent series of lateral impact tests to develop corridor bounds for a group of signals associated with a particular subject size. Comparing to the two most common methods for response normalization, the corridors generated by the new method are narrower and better retain the features in signals that are related to subject size and body shape.

Center of pressure excursion capability in performance of seated lateral-reaching tasks.

BACKGROUND: Seated center of pressure excursion capability can be used for patient evaluation in a clinical setting and in universal design. A quantification of excursion capability across age and anthropometry has not been previously reported, although some research suggests that the ischial tuberosities are the support structure limiting the excursion. METHODS: Thirty-eight neurologically healthy adults ranging in age from 21 to 74 years and including 12 obese persons performed a series of 6 lateral-reaching tasks. Participants sat on a platform such that their feet did not touch the ground, leaving their legs free to provide counterbalancing support. Data recorded from a force plate under the platform allowed calculation of the center of pressure throughout the trial and the maximum excursion for each condition was recorded. FINDINGS: The average excursion capability for the healthy, experimental population was 148 mm or 37% of seated hip breadth. Taller participants had larger maximum excursions, on average, than shorter participants, and older participants had smaller excursions than younger participants. INTERPRETATION: The greater trochanter of the femur-rather than the ischial tuberosities-appears to be the primary support structure limiting center of pressure excursion in lateral, balance-limited reaches without contralateral support. These measures and concepts can be used for design, accommodation, and clinically for patient assessment.

Effects of vehicle interior geometry and anthropometric variables on automobile driving posture.

The effects of vehicle package, seat, and anthropometric variables on posture were studied in a laboratory vehicle mockup. Participants (68 men and women) selected their preferred driving postures in 18 combinations of seat height, fore-aft steering wheel position, and seat cushion angle. Two seats differing in stiffness and seat back contour were used in testing. Driving postures were recorded using a sonic digitizer to measure the 3D locations of body landmarks. All test variables had significant independent effects on driving posture. Drivers were found to adapt to changes in the vehicle geometry primarily by changes in limb posture, whereas torso posture remained relatively constant. Stature accounts for most of the anthropometrically related variability in driving posture, and gender differences appear to be explained by body size variation. Large intersubject differences in torso posture, which are fairly stable across different seat and package conditions, are not closely related to standard anthropometric measures. The findings can be used to predict the effects of changes in vehicle and seat design on driving postures for populations with a wide range of anthropometric characteristics.

Airbag-induced fracture in a patient with osteoporosis.

Since the introduction of automotive airbag technology, patterns of airbag-induced injuries have emerged. Various types of upper-extremity trauma including fractures have been described. Previous reports have focused on the location of the forearm before deployment as the major determinant of fracture. We describe a case of forearm fracture resulting from an airbag deployment in a lupus patient with documented osteoporosis. Bone strength has recently been determined in laboratory testing to be an important factor determining airbag-induced fracture risk. An airbag-induced forearm fracture in an otherwise healthy individual may be an indicator of reduced bone strength.

The relationship between hospice length of stay and caregiver adjustment.

This study investigated the hypothesis that the greater the predeath length of stay in hospice the better would be the primary caregivers' bereavement adjustment 6 months post death. One hundred sixty caregivers from a 30% pool of hospice survivors who voluntarily returned 6-month, follow-up questionnaires were studied. Five length of stay groups were compared. There were no statistically significant differences in bereavement adjustment between caregivers with varying predeath lengths of stay. It was concluded that bereavement resolution is a complex process, and that cumulative medical illness burden, impairment of ADLs, and caregiver burden need to be considered.