Real-world data capture of daily limb loading using force-sensing insoles: Feasibility and lessons learned

Force-sensing insoles are wearable technology that offer an innovative way to measure loading outside of laboratory settings. Few studies, however, have utilized insoles to measure daily loading in real-world settings. This is an ancillary study of a randomized controlled trial examining the effect of weight loss alone, weight loss plus weighted vest, or weight loss plus resistance training on bone health in older adults. The purpose of this ancillary study was to determine the feasibility of using force-sensing insoles to collect daily limb loading metrics, including peak force, impulse, and loading rate. Forty-four participants completed a baseline visit of three, 2-minute walking trials while wearing force-sensing insoles. During month two of the intervention, 37 participants wore insoles for 4 days for 8 waking hours each day. At 6-month follow-up, participants completed three, two-minute walking trials and a satisfaction questionnaire. Criteria for success in feasibility was defined as: a) > 60 % recruitment rate; b) > 80 % adherence rate; c) > 75 % of usable data, and d) > 75 % participant satisfaction. A 77.3 % recruitment rate was achieved, with 44 participants enrolled. Participants wore their insoles an average of 7.4 hours per day, and insoles recorded an average of 5.5 hours per day. Peak force, impulse, and loading rate collected at baseline and follow-up were 100 % usable. During the real-world settings, 87.8 % of data was deemed usable with an average of 1200 min/participant. Lastly, average satisfaction was 80.5 %. These results suggest that force-sensing insoles appears to be feasible to capture real-world limb loading in older adults.

Modular incorporation of deformable spine and 3D neck musculature into a simplified human body finite element model

Spinal injuries are a concern for automotive applications, requiring large parametric studies to understand spinal injury mechanisms under complex loading conditions. Finite element computational human body models (e.g. Global Human Body Models Consortium (GHBMC) models) can be used to identify spinal injury mechanisms. However, the existing GHBMC detailed models (with high computational time) or GHBMC simplified models (lacking vertebral fracture prediction capabilities) are not ideal for studying spinal injury mechanisms in large parametric studies. To overcome these limitations, a modular 50th percentile male simplified occupant model combining advantages of both the simplified and detailed models, M50-OS + DeformSpine, was developed by incorporating the deformable spine and 3D neck musculature from the detailed GHBMC model M50-O (v6.0) into the simplified GHBMC model M50-OS (v2.3). This new modular model was validated against post-mortem human subject test data in four rigid hub impactor tests and two frontal impact sled tests. The M50-OS + DeformSpine model showed good agreement with experimental test data with an average CORrelation and Analysis (CORA) score of 0.82 for the hub impact tests and 0.75 for the sled impact tests. CORA scores were statistically similar overall between the M50-OS + DeformSpine (0.79 ± 0.11), M50-OS (0.79 ± 0.11), and M50-O (0.82 ± 0.11) models (p > 0.05). This new model is computationally 6 times faster than the detailed M50-O model, with added spinal injury prediction capabilities over the simplified M50-OS model.

Computed tomography assessment of pelvic bone density: Associations with age and pelvic fracture in motor vehicle crashes

Motor vehicle crash (MVC) occupants routinely get a computed tomography (CT) scan to screen for internal injury, and this CT can be leveraged to opportunistically derive bone mineral density (BMD). This study aimed to develop and validate a method to measure pelvic BMD in CT scans without a phantom, and examine associations of pelvic BMD with age and pelvic fracture incidence in seriously injured MVC occupants from the Crash Injury Research and Engineering Network (CIREN) study. A phantom-less muscle-fat calibration technique to measure pelvic BMD was validated using 45 quantitative CT scans with a bone calibration phantom. The technique was then used to measure pelvic BMD from CT scans of 252 CIREN occupants (ages 16+) in frontal MVCs who had sustained either abdominal or pelvic injury. Pelvic BMD was analyzed in relation to age and pelvic fracture incidence. In the validation set, phantom-based calibration vs. phantom-less muscle-fat calibration yielded similar BMD values at the anterior superior iliac spine (ASIS; R2 = 0.95, p < 0.001) and iliac crest (R2 = 0.90, p < 0.001). Pelvic BMD was measured in 150 female and 102 male CIREN occupants aged 16-89, and 25% of these occupants sustained pelvic fracture. BMD at the ASIS and iliac crest declined with age (p < 0.001). For instance, iliac crest BMD decreased an average of 25 mg/cm3 per decade of age. The rate of iliac crest BMD decline was 7.6 mg/cm3 more per decade of age in occupants with pelvic fracture compared to those not sustaining pelvic fracture. Findings suggest pelvic BMD may be a contributing risk factor for pelvic fracture in MVCs.

Assessment of finite element human body and ATD models in estimating injury risk in far-side impacts using field-based injury risk

The objective of this study was to assess the ability of finite element human body models (FEHBMs) and Anthropometric Test Device (ATD) models to estimate occupant injury risk by comparing it with field-based injury risk in far-side impacts. The study used the Global Human Body Models Consortium midsize male (M50-OS+B) and small female (F05-OS+B) simplified occupant models with a modular detailed brain, and the ES-2Re and SID-IIs ATD models in the simulated far-side crashes. A design of experiments (DOE) with a total of 252 simulations was conducted by varying lateral ΔV (10-50kph; 5kph increments), the principal direction of force (PDOF 50°, 60°, 65°, 70°, 75°, 80°, 90°), and occupant models. Models were gravity-settled and belted into a simplified vehicle model (SVM) modified for far-side impact simulations. Acceleration pulses and vehicle intrusion profiles used for the DOE were generated by impacting a 2012 Camry vehicle model with a mobile deformable barrier model across the 7 PDOFs and 9 lateral ΔV's in the DOE for a total of 63 additional simulations. Injury risks were estimated for the head, chest, lower extremity, pelvis (AIS 2+; AIS 3+), and abdomen (AIS 3+) using logistic regression models. Combined AIS 3+ injury risk for each occupant was calculated using AIS 3+ injury risk estimations for the head, chest, abdomen, and lower extremities. The injury risk calculated using computational models was compared with field-based injury risk derived from NASS-CDS by calculating their correlation coefficient. The field-based injury risk was calculated using risk curves that were created based on real-world crash data in a previous study (Hostetler et al., 2020). Occupant age (40 years), seatbelt use (belted occupant), collision deformation classification, lateral ΔV, and PDOF of the crash event were used in these curves to estimate field injury risk. Large differences in the kinematics were observed between HBM and ATD models. ATD models tended to overestimate risk in almost every case whereas HBMs yielded better risk estimates overall. Chest and lower extremity risks were the least correlated with field injury risk estimates. The overall risk of AIS 3+ injury risk was the strongest comparison to the field data-based risk curves. The HBMs were still not able to capture all the variance but future studies can be carried out that are focused on investigating their shortfalls and improving them to estimate injury risk closer to field injury risk in far-side crashes.

Application of the D3 -creatine muscle mass assessment tool to a geriatric weight loss trial: A pilot study

BACKGROUND

Traditionally, weight loss (WL) trials utilize dual energy X-ray absorptiometry (DXA) to measure lean mass. This method assumes lean mass, as the sum of all non-bone and non-fat tissue, is a reasonable proxy for muscle mass. In contrast, the D3 -creatine (D3 Cr) dilution method directly measures whole body skeletal muscle mass, although this method has yet to be applied in the context of a geriatric WL trial. The purpose of this project was to (1) describe estimates of change and variability in D3 Cr muscle mass in older adults participating in an intentional WL intervention and (2) relate its change to other measures of body composition as well as muscle function and strength.

METHODS

The INVEST in Bone Health trial (NCT04076618), used as a scaffold for this ancillary pilot project, is a three-armed, 12-month randomized, controlled trial designed to determine the effects of resistance training or weighted vest use during intentional WL on a battery of musculoskeletal health outcomes among 150 older adults living with obesity. A convenience sample of 24 participants (n = 8/arm) are included in this analysis. At baseline and 6 months, participants were weighed, ingested a 30 mg D3 Cr tracer dose, provided a fasted urine sample 3-6 days post-dosage, underwent DXA (total body fat and lean masses, appendicular lean mass) and computed tomography (mid-thigh and trunk muscle/intermuscular fat areas) scans, and performed 400-m walk, stair climb, knee extensor strength, and grip strength tests.

RESULTS

Participants were older (68.0 ± 4.4 years), mostly White (75.0%), predominantly female (66.7%), and living with obesity (body mass index: 33.8 ± 2.7 kg/m2 ). Six month total body WL was -10.3 (95% confidence interval, CI: -12.7, -7.9) kg. All DXA and computed tomography-derived body composition measures were significantly decreased from baseline, yet D3 Cr muscle mass did not change [+0.5 (95% CI: -2.0, 3.0) kg]. Of muscle function and strength measures, only grip strength significantly changed [+2.5 (95% CI: 1.0, 4.0) kg] from baseline.

CONCLUSIONS

Among 24 older adults, significant WL with or without weighted vest use or resistance training over a 6-month period was associated with significant declines in all bioimaging metrics, while D3 Cr muscle mass and muscle function and strength were preserved. Treatment assignment for the trial remains blinded; therefore, full interpretation of these findings is limited. Future work in this area will assess change in D3 Cr muscle mass by parent trial treatment group assignment in all study participants.

Comparison of morphing techniques to develop subject-specific finite element models of vertebrae

This study compared two morphing techniques (and their serial combination) to create subject-specific finite element models of 15 astronaut vertebrae. Surface deviations of the morphed models were compared against subject geometries extracted from medical images. The optimal morphing process yielded models with minimal difference in root-mean-square (RMS) deviation (C3, 0.52 ± 0.14 mm; T3, 0.34 ± 0.04 mm; L1, 0.59 ± 0.16 mm) of the subject's vertebral geometry. <1% of model elements failed quality checks and compression simulations ran to completion. This research lays the foundation for the development of subject-specific finite element models to quantify musculoskeletal changes and injury risk from spaceflight.

Characterizing thoracic morphology variation to develop representative 3D models for applications in chest trauma

BACKGROUND

Rib fracture(s) occurs in 85% of blunt chest trauma cases. Increasing evidence supports that surgical intervention, particularly for multiple fractures, may improve outcomes. Thoracic morphology diversity across ages and sexes is important to consider in the design and use of surgical intervention devices in chest trauma. However, research on non-average thoracic morphology is lacking.

METHODS

The rib cage was segmented from patient computed tomography (CT) scans to create 3D point clouds. These point clouds were uniformly oriented and chest height, width, and depth were measured. Size categorization was determined by grouping each dimension into small, medium, and large tertiles. From small and large size combinations, subgroups were extracted to develop thoracic 3D models of the rib cage and surrounding soft tissue.

RESULTS

The study population included 141 subjects (48% male) ranging from age 10-80 with ∼20 subjects/age decade. Mean chest volume increased with age by 26% from the age groups 10-20 to 60-70, with 11% of this increase occurring between the youngest groups of 10-20 and 20-30. Across all ages, chest dimensions were ∼10% smaller in females and chest volume was highly variable (SD: ±3936.5 cm3). Representative thoracic models of four males (ages 16, 24, 44, 48) and three females (ages 19, 50, 53) were developed to characterize morphology associated with combinations of small and large chest dimensions.

CONCLUSIONS

The seven models developed cover a broad range of non-average thoracic morphologies and can serve as a basis for informing device design, surgical planning, and injury risk assessments.

Strategies to reduce the onset of sleeve gastrectomy associated bone loss (STRONG BONES): Trial design and methods

Background

Despite recognized improvements in obesity-related comorbidities, mounting evidence implicates surgical weight loss in the onset of skeletal fragility. Sleeve gastrectomy (SG) is the most commonly performed bariatric procedure and is associated with 3-7% axial bone loss in the year following surgery. Bisphosphonates are FDA-approved medications for the prevention and treatment of age-related bone loss and may represent a strategy to reduce bone loss following SG surgery.

Methods

The Strategies to Reduce the Onset of Sleeve Gastrectomy Associated Bone Loss (STRONG BONES) trial (NCT04922333) is designed to definitively test whether monthly administration of the bisphosphonate, risedronate, for six months can effectively counter SG-associated bone loss. Approximately 120 middle-aged and older (≥40 years) SG patients will be randomized to six months of risedronate or placebo treatment, with skeletal outcomes assessed at baseline, six, and 12-months post-surgery. The primary outcome of the trial is 12-month change in total hip areal bone mineral density (aBMD), measured by dual energy x-ray absorptiometry (DXA). This will be complemented by DXA-acquired aBMD assessment at other skeletal sites and quantitative computed tomography (QCT) derived changes in bone quality. Change in muscle mass and function will also be assessed, as well as biomarkers of bone health, turnover, and crosstalk, providing mechanistic insight into intervention-related changes to the bone-muscle unit.

Discussion

Results from the STRONG BONES trial have the potential to influence current clinical practice by determining the ability of bisphosphonate use to mitigate bone loss and concomitant fracture risk in middle-aged and older SG patients.

Associations between lower extremity muscle fat fraction and motor performance in myotonic dystrophy type 2: A pilot study

INTRODUCTION/AIMS

Although muscle structure measures from magnetic resonance imaging (MRI) have been used to assess disease severity in muscular dystrophies, little is known about how these measures are affected in myotonic dystrophy type 2 (DM2). We aim to characterize lower extremity muscle fat fraction (MFF) as a potential biomarker of disease severity, and evaluate its relationship with motor performance in DM2.

METHODS

3-Tesla MRIs were obtained from nine patients with DM2 and six controls using a T1W-Dixon protocol. To calculate MFF, muscle volumes were segmented from proximal, middle, and distal regions of the thigh and calf. Associations between MFF and motor performance were calculated using Spearman's correlations (ρ).

RESULTS

Mean age of DM2 participants was 62 ± 11 y (89% female), and mean symptom duration was 20 ± 12 y. Compared to controls, the DM2 group had significantly higher MFF in the thigh and the calf segments (p-value = .002). The highest MFF at the thigh in DM2 was located in the posterior compartment (39.7 ± 12.9%) and at the calf was the lateral compartment (31.5 ± 8.7%). In the DM2 group, we found a strong correlation between the posterior thigh MFF and the 6-min walk test (ρ = -.90, p-value = .001). The lateral calf MFF was also strongly correlated with the step test (ρ = -0.82, p-value = .006).

DISCUSSION

Our pilot data suggest a potential correlation between lower extremity MFF and some motor performance tests in DM2. Longitudinal studies with larger sample sizes are required to validate MFF as a marker of disease severity in DM2.

Effect of exercise modality and weight loss on changes in muscle and bone quality in older adults with obesity

BACKGROUND

Little is known about the effect of exercise modality during a dietary weight loss program on muscle size and quality, as measured by computed tomography (CT). Even less is known about how CT-derived changes in muscle track with changes in volumetric bone mineral density (vBMD) and bone strength.

METHODS

Older adults (66 ± 5 years, 64 % women) were randomized to 18-months of diet-induced weight loss (WL), WL with aerobic training (WL + AT), or WL with resistance training (WL + RT). CT-derived muscle area, radio-attenuation and intermuscular fat percentage at the trunk and mid-thigh were determined at baseline (n = 55) and 18-month follow-up (n = 22-34), and changes were adjusted for sex, baseline value, and weight lost. Lumbar spine and hip vBMD and finite element-derived bone strength were also measured.

RESULTS

After adjustment for the weight lost, muscle area losses at the trunk were -7.82 cm2 [-12.30, -3.35] for WL, -7.72 cm2 [-11.36, -4.07] for WL + AT, and -5.14 cm2 [-8.65, -1.63] for WL + RT (p < 0.001 for group differences). At the mid-thigh, decreases were -6.20 cm2 [-10.39, -2.02] for WL, -7.84 cm2 [-11.19, -4.48] for WL + AT, and -0.60 cm2 [-4.14, 2.94] for WL + RT; this difference between WL + AT and WL + RT was significant in post-hoc testing (p = 0.01). Change in trunk muscle radio-attenuation was positively associated with change in lumbar bone strength (r = 0.41, p = 0.04).

CONCLUSIONS

WL + RT better preserved muscle area and improved muscle quality more consistently than WL + AT or WL alone. More research is needed to characterize the associations between muscle and bone quality in older adults undertaking weight loss interventions.

Development and Validation of an Active Muscle Simplified Finite Element Human Body Model in a Standing Posture

Active muscles play an important role in postural stabilization, and muscle-induced joint stiffening can alter the kinematic response of the human body, particularly that of the lower extremities, under dynamic loading conditions. There are few full-body human body finite element models with active muscles in a standing posture. Thus, the objective of this study was to develop and validate the M50-PS+Active model, an average-male simplified human body model in a standing posture with active musculature. The M50-PS+Active model was developed by incorporating 116 skeletal muscles, as one-dimensional beam elements with a Hill-type material model and closed-loop Proportional Integral Derivative (PID) controller muscle activation strategy, into the Global Human Body Models Consortium (GHBMC) simplified pedestrian model M50-PS. The M50-PS+Active model was first validated in a gravity standing test, showing the effectiveness of the active muscles in maintaining a standing posture under gravitational loading. The knee kinematics of the model were compared against volunteer kinematics in unsuited and suited step-down tests from NASA's active response gravity offload system (ARGOS) laboratory. The M50-PS+Active model showed good biofidelity with volunteer kinematics with an overall CORA score of 0.80, as compared to 0.64 (fair) in the passive M50-PS model. The M50-PS+Active model will serve as a useful tool to study the biomechanics of the human body in vehicle-pedestrian accidents, public transportation braking, and space missions piloted in a standing posture.

Sensitivity Analysis for Multidirectional Spaceflight Loading and Muscle Deconditioning on Astronaut Response

A sensitivity analysis for loading conditions and muscle deconditioning on astronaut response for spaceflight transient accelerations was carried out using a mid-size male human body model with active musculature. The model was validated in spaceflight-relevant 2.5-15 g loading magnitudes in seven volunteer tests, showing good biofidelity (CORA: 0.69). Sensitivity analysis was carried out in simulations varying pulse magnitude (5, 10, and 15 g), rise time (32.5 and 120 ms), and direction (10 directions: frontal, rear, vertical, lateral, and their combination) along with muscle size change (± 15% change) and responsiveness (pre-braced, relaxed, vs. delayed response) changes across 600 simulations. Injury metrics were most sensitive to the loading direction (50%, partial-R²) and least sensitive to muscle size changes (0.2%). The pulse magnitude also had significant effect on the injury metrics (16%), whereas muscle responsiveness (3%) and pulse rise time (2%) had only slight effects. Frontal and upward loading directions were the worst for neck, spine, and lower extremity injury metrics, whereas rear and downward directions were the worst for head injury metrics. Higher magnitude pulses and pre-bracing also increased the injury risk.

Quantifying Cardiothoracic Variation with Posture and Respiration to Inform Cardiac Device Design

PURPOSE

With extravascular implantable cardioverter defibrillator leads placed beneath the sternum, it is important to quantify heart motion relative to the rib cage with postural changes and respiration.

METHODS

MRI scans from five males and five females were collected in upright and supine postures at end inspiration [n = 10 each]. Left and right decubitus [n = 8 each] and prone [n = 5] MRIs at end inspiration and supine MRIs at end expiration [n = 5] were collected on a subset. Four cardiothoracic measurements, six cardiac measurements, and six cardiac landmarks were collected to measure changes across different postures and stages of respiration.

RESULTS

The relative location of the LV apex to the nearest intercostal space was significantly different between the supine and decubitus postures (average ± SD difference: - 15.7 ± 11.4 mm; p < 0.05). The heart centroid to xipho-sternal junction distance was 9.7 ± 7.9 mm greater in the supine posture when compared to the upright posture (p < 0.05). Cardiac landmark motion in the lateral direction was largest due to postural movement (range 23-50 mm) from the left decubitus to the right decubitus posture, and less influenced by respiration (5-17 mm). Caudal-cranial displacement was generally larger due to upright posture (13-23 mm caudal) and inspiration (7-20 mm cranial).

CONCLUSIONS

This study demonstrates that the location of the heart with respect to the rib cage varies with posture and respiration. The gravitational effects of postural shifts on the heart position are roughly 2-3 times larger than the effects of normal respiration.

Effect of Active Muscles on Astronaut Kinematics and Injury Risk for Piloted Lunar Landing and Launch While Standing

While astronauts may pilot future lunar landers in a standing posture, the response of the human body under lunar launch and landing-related dynamic loading conditions is not well understood. It is important to consider the effects of active muscles under these loading conditions as muscles stabilize posture while standing. In the present study, astronaut response for a piloted lunar mission in a standing posture was simulated using an active human body model (HBM) with a closed-loop joint-angle based proportional integral derivative controller muscle activation strategy and compared with a passive HBM to understand the effects of active muscles on astronaut body kinematics and injury risk. While head, neck, and lumbar spine injury risk were relatively unaffected by active muscles, the lower extremity injury risk and the head and arm kinematics were significantly changed. Active muscle prevented knee-buckling and spinal slouching and lowered tibia injury risk in the active vs. passive model (revised tibia index: 0.02-0.40 vs. 0.01-0.58; acceptable tolerance: 0.43). Head displacement was higher in the active vs. passive model (11.6 vs. 9.0 cm forward, 6.3 vs. 7.0 cm backward, 7.9 vs. 7.3 cm downward, 3.7 vs. 2.4 cm lateral). Lower arm movement was seen with the active vs. passive model (23 vs. 35 cm backward, 12 vs. 20 cm downward). Overall simulations suggest that the passive model may overpredict injury risk in astronauts for spaceflight loading conditions, which can be improved using the model with active musculature.

Risedronate use may blunt appendicular lean mass loss secondary to sleeve gastrectomy: Results from a pilot randomized controlled trial

Background

Despite robust weight loss and cardiometabolic benefit, lean mass loss following sleeve gastrectomy (SG) confers health risk. Bisphosphonates are a potential therapeutic agent for lean mass maintenance. Thus, our objective was to explore the effect of six months of risedronate (vs placebo) on change in dual energy x-ray absorptiometry (DXA) and computed tomography (CT) derived lean mass metrics in the year following SG.

Methods

24 SG patients were randomized to six months of 150 mg oral risedronate or placebo capsules (NCT03411902). Body composition was assessed at baseline and six months with optional 12-month follow-up using whole-body DXA and CT at the lumbar spine and mid-thigh. Group treatment effects and 95% CIs were generated from a mixed model using contrast statements at six and 12 months, adjusted for baseline values.

Results

Of 24 participants enrolled [55.7±6.7 years (mean±SD), 79% Caucasian, 83% women, body mass index (BMI) 44.7±6.3kg/m2], 21 returned for six-month testing, and 14 returned for 12-month testing. Six-month weight loss was -16.3 kg (-20.0, -12.5) and -20.9 kg (-23.7, -18.1) in the risedronate and placebo groups, respectively (p=.057). Primary analysis at six-months revealed a non-significant sparing of appendicular lean mass in the risedronate group compared to placebo [-1.2 kg (-2.3, -0.1) vs -2.1 kg (-3.0, -1.2)]; p=.20. By 12-months, the risedronate group displayed no change in appendicular lean mass from baseline [-0.5 kg (-1.5, 0.6)]; however, the placebo group experienced significantly augmented loss [-2.9 kg (-3.6, -2.1)].

Conclusion

Pilot data indicate risedronate treatment may mitigate appendicular lean mass loss following SG. Further study is warranted.

Effects of Standing, Upright Seated, vs. Reclined Seated Postures on Astronaut Injury Biomechanics for Lunar Landings

Astronauts may pilot a future lunar lander in a standing or upright/reclined seated posture. This study compared kinematics and injury risk for the upright/reclined (30°; 60°) seated vs. standing postures for lunar launch/landing using human body modeling across 30 simulations. While head metrics for standing and upright seated postures were comparable to 30 cm height jumps, those of reclined postures were closer to 60 cm height jumps. Head linear acceleration for 60° reclined posture in the 5 g/10 ms pulse exceeded NASA's tolerance (10.1 g; tolerance: 10 g). Lower extremity metrics exceeding NASA's tolerance in the standing posture (revised tibia index: 0.36-0.53; tolerance: 0.43) were lowered in seated postures (0.00-0.04). Head displacement was higher in standing vs. seated (9.0 cm vs. 2.4 cm forward, 7.0 cm vs. 1.3 cm backward, 2.1 cm vs. 1.2 cm upward, 7.3 cm vs. 0.8 cm downward, 2.4 cm vs. 3.2 cm lateral). Higher arm movement was seen with seated vs. standing (40 cm vs. 25 cm forward, 60 cm vs. 15 cm upward, 30 cm vs. 20 cm downward). Pulse-nature contributed more than 40% to the injury metrics for seated postures compared to 80% in the standing posture. Seat recline angle contributed about 22% to the injury metrics in the seated posture. This study established a computational methodology to simulate the different postures of an astronaut for lunar landings and generated baseline injury risk and body kinematics data.

Effects of muscle quantity and bone mineral density on injury and outcomes in older adult motor vehicle crash occupants

Objectives: Quantify the independent and combined effects of abdominal muscle quantity and lumbar bone mineral density (BMD) on injury risk and in-hospital outcomes in severely injured motor vehicle crash (MVC) occupants ages 50 and older.Methods: Skeletal muscle area measurements of MVC occupants were obtained through semi-automated segmentation of an axial computed tomography (CT) slice at the L3 vertebra. An occupant height-normalized Skeletal Muscle Index (SMI) was calculated - a defining metric of sarcopenia and low muscle mass (sarcopenia thresholds: <38.5 cm2/m2 females; <52.4 cm2/m2 males). Lumbar BMD was obtained using a validated, phantomless CT calibration method (osteopenia threshold: <145 mg/cm3). SMI and BMD values were used to categorize occupants, and logistic regression was used to associate sarcopenia, osteopenia, and osteosarcopenia predictors to injury outcomes (e.g., Injury Severity Score (ISS), maximum Abbreviated Injury Scale (MAIS) score, fractures) and hospital outcomes (e.g., length of stay, ICU days).Results: Of the 336 occupants, 210 (63%) were female (mean ± SD: age 66.3 ± 10.6). SMI was 41.7 ± 8.0 cm2/m2 in females and 51.2 ± 10.8 cm2/m2 in males. Based on SMI, 40% of females and 55% of males were classified as sarcopenic. BMD was 163.2 ± 38.3 mg/cm3 in females and 164.1 ± 35.4 mg/cm3 in males, with 41% of females and 33% of males classified as osteopenic. Prevalence of both conditions (osteosarcopenia) was similar between females (21%) and males (22%). Incidence of low SMI and BMD increased with age. Sarcopenic individuals were less likely to sustain a MAIS 2+ thorax injury and had longer ICU stays. Osteopenic individuals were more likely to sustain upper extremity injuries and fractures, and were less likely to be discharged to a rehabilitation facility. Osteosarcopenic individuals were less likely to be ventilated or admitted to the ICU but tended to spend more time on the ventilator if placed on one.Conclusions: Osteosarcopenia was not associated with any injury outcomes, but sarcopenia was associated with thoracic injury and osteopenia was associated with upper extremity injury incidence. Sarcopenia was only associated with ICU length of stay, while osteopenia was only associated with discharge destination. Osteosarcopenia was associated with likelihood of being ventilated, being admitted to the ICU, and with increased length of ventilation.

Body mass index influence on lap belt position and abdominal injury in frontal motor vehicle crashes

OBJECTIVE

As obesity rates climb, it is important to study its effects on motor vehicle safety due to differences in restraint interaction and biomechanics. Previous studies have shown that an abdominal seatbelt sign (referred hereafter as seatbelt sign) sustained from motor vehicle crashes (MVCs) is associated with abdominal trauma when located above the anterior superior iliac spine (ASIS). This study investigates whether placement of the lap belt causing a seatbelt sign is associated with abdominal organ injury in occupants with increased body mass index (BMI). We hypothesized that higher BMI would be associated with a higher incidence of superior placement of the lap belt to the ASIS level, and a higher incidence of abdominal organ injury.

METHODS

A retrospective data analysis was performed using 230 cases that met inclusion criteria (belted occupant in a frontal collision that sustained at least one abdominal injury) from the Crash Injury Research and Engineering Network (CIREN) database. Computed tomography (CT) scans were rendered to visualize fat stranding to determine the presence of a seatbelt sign. 146 positive seatbelt signs were visualized. ASIS level was measured by adjusting the transverse slice of the CT to the visualized ASIS level, which was used to determine seatbelt sign location as superior, on, or inferior to the ASIS.

RESULTS

Obese occupants had a significantly higher incidence of superior belt placement (52%) vs on-ASIS placement (24%) compared to their normal (27% vs 67%) BMI counterparts (p < 0.001). Notable trends included obese occupants with superior placement having less abdominal organ injury incidence than those with on-ASIS belt placement (42% superior placement vs 55% on-ASIS). In non-obese occupants, there was a higher incidence of abdominal organ injury with superior lap belt placement compared to on-ASIS placement counterparts (Normal BMI: 62% vs 41%, Overweight: 57% vs 43%).

CONCLUSIONS

In CIREN occupants with abdominal injury, those with obesity are more prone to positioning the lap belt superior to the ASIS, though the impact on abdominal injury incidence remains a key point for continued exploration into how occupant BMI affects crash safety and belt design.

Age targeted human body models indicate increased thoracic injury risk with aging

OBJECTIVE

The objective of this study is to generate age targeted versions of the male and female Global Human Body Models Consortium (GHBMC) occupant human body models (HBMs), to validate each in frontal impacts, and to assess rib fracture probability of each.

METHODS

Six age targeted models were developed based on the GHBMC average male and small female occupant models (M50-O v6.0 and F05-O v6.0, respectively). All age targeted models were modified to represent population means for height, weight, shape, and relevant material properties. The thin plate spline method was used to morph models, and material properties were modified using available literature. Validation focused on chest response. Models were evaluated in a rigid body frontal chest impact at 6.7 m/s. Furthermore, the male and female age targeted models were evaluated against published data from 40 km/hr and 30 km/hr frontal sled tests respectively.

RESULTS

Chest deflections and landmark kinematics reasonably matched the respective corridors in the M50-O and F05-O aged models. Regional probability of rib fracture was assessed using probabilistic methods based on cortex strain. Increasing rib fracture with age was observed in both impacts for both sexes. For the rigid chest impact, the M50-O 70YO resulted in 10 ribs exceeding 50% probability of fracture whereas the younger ages reported 4 to 6 ribs exceeding the same probability. In the same simulation, the F05-O 70YO resulted in 8 regions exceeding 50% probability of rib fracture as opposed to 3 and 0 such regions at the youngest ages. Sled simulation demonstrated similar trends. The 70YO age adjusted models best aligned with the reported extent of fractures from the referenced PMHS studies, which tend to be composed of subjects of advanced age.

CONCLUSIONS

Age targeted HBMs demonstrated increased fracture probability with age when subjected to equivalent impacts. Gross model kinematics approximate PMHS data but showed little difference between targeted age models. The findings indicate that while gross kinematics are unaffected by age-targeting models, such models can capture trends of increased thoracic injury risk observed in experimental and field studies, and further suggest their potential use to target interventions for vulnerable driving populations, such as older adults.

Change in Lumbar Muscle Size and Composition on MRI with Long-Duration Spaceflight

Prolonged microgravity results in muscle atrophy, especially among the anti-gravity spinal muscles. How individual paravertebral muscle groups change in size and composition with spaceflight needs further exploration. This study investigates lumbar spine musculature changes among six crewmembers on long-duration space missions using non-invasive measurement of muscle changes with magnetic resonance imaging (MRI). Pre- and post-flight lumbar images were analyzed for changes in cross-sectional area, volume, and fat infiltration of the psoas (PS), quadratus lumborum (QL), and paraspinal [erector spinae and multifidus (ES + MF)] muscles using mixed models. Crewmembers used onboard exercise equipment, including a cycle ergometer (CEVIS), treadmill (T2/COLBERT), and the advanced resistive exercise device (ARED). Correlations were used to assess muscle changes related to exercise modality. There was substantial variability in muscle changes across crewmembers but collectively a significant decrease in paraspinal area (- 9.0 ± 4.8%, p = 0.04) and a significant increase in QL fat infiltration (7.3 ± 4.1%, p = 0.05). More CEVIS time may have protected against PS volume loss (p = 0.05) and PS fat infiltration (p < 0.01), and more ARED usage may have protected against ES + MF volume loss (p = 0.05). Crewmembers using modern onboard exercise equipment may be less susceptible to muscle changes. However, variability between crewmembers and muscle size and quality losses suggest additional research is needed to ensure in-flight countermeasures preserve muscle health.

Age-based differences in the disability of spine injuries in pediatric and adult motor vehicle crash occupants

OBJECTIVE

The objective was to develop a disability-based metric for quantifying disability rates as a result of motor vehicle crash (MVC) spine injuries and compare functional outcomes between pediatric and adult subgroups.

METHODS

Disability rate was quantified using Functional Independence Measure (FIM) scores within the National Trauma Data Bank-Research Data System for the top 95% most frequent Abbreviated Injury Scale (AIS) 3 spine injuries (14 unique injuries). Pediatric (7-18 years), young adult (19-45 years), middle-aged adult (46-65 years), and older adult (66+ years) MVC occupants with FIM scores available and at least one of the 14 spine injuries were included. FIM scores of 1 or 2 at time of discharge were used to define disability and correspond to full functional or modified dependence in self-feeding, locomotion, and/or verbal expression. Disability rate was evaluated on a per injury basis for each AIS 3 spine injury and calculated as the proportion of cases associated with disability (i.e. FIM of 1 or 2) out of the total cases of that particular injury. Disability rates were calculated with and without the exclusion of cases with severe co-injuries (AIS 4+) to minimize bias from additional non-spinal injuries that could have contributed to disability. Associations between adjusted disability rates and existing mortality rates were investigated.

RESULTS

Locomotion impairment alone was the most frequent disability type for the top 14 AIS 3 spine injuries (7 cervical, 4 thoracic, and 3 lumbar) across all age groups and spine regions. Adjusted and unadjusted disability rates ranged from 0-69%. Adjusted disability rates increased with age: 14.8 ± 10% (mean ± SD) in pediatrics to 16.2 ± 6.6% (young adults), 29.2 ± 10.9% (middle-aged adults), and 45.0 ± 12.2% (older adults). Among all adult populations, adjusted mortality and disability rates were positively correlated (R²>0.24), with disability rates consistently greater than corresponding mortality rates.

CONCLUSIONS

Older adults had significantly greater disability rates associated with MVC spine injuries across all spinal regions. MVC disability rates for pediatrics were considerably lower. Overall, rates of mortality were significantly lower than rates of disability. The adjusted disability rates developed can supplement existing injury metrics by accounting for age- and location-specific functional implications of MVC spine injuries.

Protocol for a pilot randomised controlled trial of zoledronic acid to prevent bone loss following sleeve gastrectomy surgery

INTRODUCTION

Sleeve gastrectomy (SG) is an increasingly used and effective treatment for obesity; however, the rapid weight loss associated with SG adversely affects bone metabolism predisposing patients to skeletal fragility. Bisphosphonate medications have been evaluated for safety and efficacy in combating bone loss in patients with osteoporosis, but their use in SG-induced bone loss is limited. The goal of this study is to investigate how a one-time infusion of zoledronic acid compares to placebo, in its ability to combat SG-associated bone loss.

METHODS AND ANALYSIS

This research protocol is a 9-month, pilot randomized controlled trial (RCT) involving 30 adult SG patients randomised to receive an infusion of either 5 mg of zoledronic acid or placebo, 6 weeks following surgery. To be included participants must be <350 lbs/158.8 kg, free of bone-impacting pathologies or medications, and must have adequate serum calcium and vitamin D levels at baseline. The primary outcome is change in areal bone mineral density (aBMD) at the total hip. Secondary outcomes include change in aBMD of the femoral neck, and lumbar spine, and change in volumetric BMD at the lumbar spine. The primary aim will be tested using a linear mixed model fit with total hip aBMD at 9 months as the outcome. Treatment, participant sex and menopausal status will be considered in analysis. Groups will be compared using contrast statements at 9 months, with change over 9 months being the primary comparison.

ETHICS AND DISSEMINATION

This study was approved by the Institutional Review Board of the University of Nebraska Medical Center (IRB820-19). Written consent will be obtained from participants at enrolment by trained staff. Careful and thorough explanation are used in obtainment of consent and voluntariness is emphasised throughout the trial. The findings of this study will be presented locally, nationally, and published in peer-reviewed journals. Additional details will be reported on ClinicalTrials.gov.

TRIAL REGISTRATION NUMBER

NCT04279392.

Development and implementation of a time- and computationally-efficient methodology for reconstructing real-world crashes using finite element modeling to improve crash injury research investigations

Eleven Crash Injury Research and Engineering Network (CIREN) frontal crashes were reconstructed using a novel, time-efficient methodology involving a simplified vehicle model. Kinematic accuracy was assessed using novel kinematic scores between 0-1 and chest injury was assessed using literature-defined injury metric time histories. The average kinematic score across all simulations was 0.87, indicating good kinematic accuracy. Time histories for chest compression, rib strain, shoulder belt force, and steering column force discerned the most causative components of chest injury in all cases. Abbreviated Injury Scale (AIS) 2+ and AIS 3+ chest injury risk functions using belt force identified chest injury with 81.8% success.

Risedronate use to attenuate bone loss following sleeve gastrectomy: Results from a pilot randomized controlled trial

The purpose of this study was to explore the efficacy of 150 mg once monthly oral risedronate use in the prevention of sleeve gastrectomy (SG) associated bone loss. Twenty-four SG patients (56 ± 7 years, 83% female, 21% black) were randomized to risedronate or placebo for 6 months, with an optional 12-month assessment. Outcome measures included 6 (n = 21) and 12 (n = 14) month change in dual energy x-ray absorptiometry-acquired regional areal bone mineral density (aBMD). Six-month treatment effect estimates [mean (95% CI)] revealed significant between group aBMD differences at the femoral neck [risedronate: +0.013 g/cm² (-0.021, 0.046) vs. placebo: -0.041 g/cm² (-0.067, -0.015)] and lumbar spine [risedronate: +0.028 g/cm² (-0.006, 0.063) vs. placebo: -0.029 g/cm² (-0.054, -0.004)]; both p ≤ 0.02. When followed postoperatively to 12 months, differential aBMD treatment effects were observed at the total hip [risedronate: -0.035 g/cm² (-0.061, -0.009) vs. placebo: -0.072 g/cm² (-0.091, -0.052)] and lumbar spine [risedronate: +0.012 g/cm² (-0.038, 0.063) vs. placebo: -0.052 g/cm² (-0.087, -0.017)]; both p < 0.05. Preliminary treatment effect estimates signal 6 months of risedronate use may be efficacious in reducing aBMD loss at the axial skeleton post-SG, with benefit largely maintained throughout the 1-year postoperative period. Confirmatory data from an adequately powered trial are needed.

Effect of Dietary Protein Intake on Bone Mineral Density and Fracture Incidence in Older Adults in the Health, Aging, and Body Composition Study

BACKGROUND

Dietary recommendations may underestimate the protein older adults need for optimal bone health. This study sought to determine associations of protein intake with bone mineral density (BMD) and fracture among community-dwelling White and Black older adults.

METHOD

Protein as a percentage of total energy intake (TEI) was assessed with a Food Frequency Questionnaire in 2160 older adults (73.5 ± 2.8 years; 51.5% women; 35.8% Black) in the Health, Aging, and Body Composition prospective cohort. Hip, femoral neck, and whole body BMD was assessed by dual-energy x-ray absorptiometry at baseline and 4 years, and lumbar trabecular, cortical, and integral BMD was assessed by computed tomography at baseline and 5 years. Fragility fractures over 5 years were adjudicated from self-report data collected every 6 months. Associations with tertiles of protein intake were assessed using analysis of covariance for BMD and multivariate Cox regression for fracture, adjusting for confounders.

RESULTS

Participants in the upper protein tertile (≥15% TEI) had 1.8%-6.0% higher mean hip and lumbar spine BMD compared to the lower protein tertile (<13% TEI; p < .05). Protein intake did not affect change in BMD at any site over the follow-up period. Participants in the upper protein tertile had a reduced risk of clinical vertebral fracture over 5 years of follow-up (hazard ratio: 0.36 [95% confidence interval: 0.14, 0.97] vs lower protein tertile, p = .04).

CONCLUSIONS

Older adults with higher protein intake (≥15% TEI) had higher BMD at the hip, whole body, and lumbar spine, and a lower risk of vertebral fracture.

The relationship of body mass index, belt placement, and abdominopelvic injuries in motor vehicle crashes: A Crash Injury Research and Engineering Network (CIREN) study

OBJECTIVE

Obesity has important implications for motor vehicle safety due to altered crash injury responses from increased mass and improper seatbelt placement. Abdominal seatbelt signs (ASBS) above the anterior superior iliac spine (ASIS) in motor vehicle crashes (MVCs) often correlate with abdominopelvic trauma. We investigated the relationship of body mass index (BMI), lap belt placement, and the incidence of abdominopelvic injury using computed tomography (CT) evaluation for subcutaneous ASBS mark and its location relative to the ASIS.

METHODS

A retrospective analysis of 235 Crash Injury Research and Engineering Network (CIREN) cases and their associated abdominal injuries was conducted. CT Scans were analyzed to visualize fat stranding. 150 positive ASBS were found and their ASBS mark location was classified as superior, on, or inferior to the ASIS.

RESULTS

Obese occupants had a higher incidence rate of belt placement superior to the ASIS, and occupants with normal BMI had a higher incidence of proper belt placement (p < 0.05). Trends of interest developed, notably that non-obese occupants with superior belt placement had increased incidence of internal abdominopelvic organ injury compared to those with proper belt placement (Normal BMI: 53.3% superior vs 39.4% On-ASIS, Overweight: 47.8% superior vs 34.7% On-ASIS).

CONCLUSIONS

Utilizing CT scans to confirm ASBS and lap belt placement relative to the ASIS, superior belt placement above the ASIS was associated with elevated BMI and a trend of increasing incidence of internal abdominopelvic organ injury.

Automated Muscle Measurement on Chest CT Predicts All-Cause Mortality in Older Adults From the National Lung Screening Trial

BACKGROUND

Muscle metrics derived from computed tomography (CT) are associated with adverse health events in older persons, but obtaining these metrics using current methods is not practical for large datasets. We developed a fully automated method for muscle measurement on CT images. This study aimed to determine the relationship between muscle measurements on CT with survival in a large multicenter trial of older adults.

METHOD

The relationship between baseline paraspinous skeletal muscle area (SMA) and skeletal muscle density (SMD) and survival over 6 years was determined in 6,803 men and 4,558 women (baseline age: 60-69 years) in the National Lung Screening Trial (NLST). The automated machine learning pipeline selected appropriate CT series, chose a single image at T12, and segmented left paraspinous muscle, recording cross-sectional area and density. Associations between SMA and SMD with all-cause mortality were determined using sex-stratified Cox proportional hazards models, adjusted for age, race, height, weight, pack-years of smoking, and presence of diabetes, chronic lung disease, cardiovascular disease, and cancer at enrollment.

RESULTS

After a mean 6.44 ± 1.06 years of follow-up, 635 (9.33%) men and 265 (5.81%) women died. In men, higher SMA and SMD were associated with a lower risk of all-cause mortality, in fully adjusted models. A one-unit standard deviation increase was associated with a hazard ratio (HR) = 0.85 (95% confidence interval [CI] = 0.79, 0.91; p < .001) for SMA and HR = 0.91 (95% CI = 0.84, 0.98; p = .012) for SMD. In women, the associations did not reach significance.

CONCLUSION

Higher paraspinous SMA and SMD, automatically derived from CT exams, were associated with better survival in a large multicenter cohort of community-dwelling older men.

Injury risk curves in far-side lateral motor vehicle crashes by AIS level, body region and injury code

OBJECTIVE

The objective of this study was to develop injury risk curves as a function of change in vehicle velocity for occupants in far-side lateral motor vehicle crashes (MVCs) by AIS level, body region, and specific AIS codes that commonly occur in this crash mode.

METHODS

The National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) years 2000-2015 database was queried, resulting in 4,495 non-weighted far-side crashes. For each case, occupant age, sex, and the following metadata were collected: vehicle model year, vehicle body type, lateral delta-v, normalized PDOF, multiple impacts, belt use, seat position, object contacted, striking vehicle body type, maximum crush extent and side airbag deployment. Multivariable logistic regression was used to develop risk curves for AIS 2+ through 5+ injuries, AIS 2+ injuries by body region (head, thorax, lower extremity), and for each of the 10 most frequent far-side AIS 2+ injuries. Significant covariates were determined by backwards elimination (p < 0.05). The full dataset and a subsampled dataset of only cases with side airbag deployment were used to develop risk curves.

RESULTS

For AIS 2+ through 5+ injury, greater delta-V was associated with greater injury risk (OR's: 2.48-3.66 per 11.9 kph increase) and belt use was associated with lower risk (OR's: 0.04-0.36 compared to unbelted). Multiple impacts were significant predictors of increased AIS 3+, 4+ and 5+ injury risk (OR's: 2.56, 2.27 and 2.83 compared to single impact). For AIS 2+ body region injuries, lateral delta-V and maximum CDC extent were positively associated with increased head, thorax and lower extremity injury risk while belt use was associated with lower risk. Increased lateral delta-v, unbelted status, and greater maximum CDC extent frequently increased injury risk for the most common far-side injuries. Side airbag deployment was not a significant covariate for the injury risk models.

CONCLUSIONS

The resulting risk models expand upon previous literature gaps to provide a more comprehensive view of contributors to injury risk for occupants in far-side MVCs. This study yields risk curves based on the latest available NASS-CDS data.

Risedronate to Prevent Bone Loss After Sleeve Gastrectomy: Study Design and Feasibility Report of a Pilot Randomized Controlled Trial

Mounting evidence implicates bariatric surgery as a cause of increased skeletal fragility and fracture risk. Bisphosphonate therapy reduces osteoporotic fracture risk and may be effective in minimizing bone loss associated with bariatric surgery. The main objective of this pilot randomized controlled trial (RCT; Clinical Trial No. NCT03411902) was to determine the feasibility of recruiting, treating, and following 24 older patients who had undergone sleeve gastrectomy in a 6 month RCT examining the efficacy of 150‐mg once‐monthly risedronate (versus placebo) in the prevention of surgical weight‐loss–associated bone loss. Feasibility was defined as: (i) >30% recruitment yield, (ii) >80% retention, (iii) >80% pills taken, (iv) <20% adverse events (AEs), and (v) >80% participant satisfaction. Study recruitment occurred over 17 months. Seventy participants were referred, with 24 randomized (34% yield) to risedronate (n = 11) or placebo (n = 13). Average age was 56 ± 7 years, 83% were female (63% postmenopausal), and 21% were black. The risedronate group had a higher baseline BMI than the placebo group (48.1 ± 7.2 versus 41.9 ± 3.8 kg/m²). The 10‐year fracture risk was low (6.0% major osteoporotic fracture, 0.4% hip fracture); however, three individuals (12.5%, all risedronate group) were osteopenic at baseline. Twenty‐one participants returned for 6‐month follow‐up testing (88% retention) with all (n = 3) loss to follow‐up occurring in the risedronate group. Average number of pills taken among completers was 5.9 ± 0.4 and 6.0 ± 0.0 in the risedronate and placebo groups, respectively (p = 0.21), with active participants taking >80% of allotted pills. Five AEs (3.7% AE rate) were reported; one definitely related, four not related, and none serious. All participants reported high satisfaction with participation in the study. Use of bisphosphonates as a novel therapeutic to preserve bone density in patients who had undergone a sleeve gastrectomy appears feasible and well‐tolerated. Knowledge gained from this pilot RCT will be used to inform the design of an appropriately powered trial.

Clinical Trial Registration

http://clinicaltrials.gov/show/NCT03411902. Weight Loss With Risedronate for Bone Health. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Estimated crash injury risk and crash characteristics for motorsport drivers

OBJECTIVE

Motorsport crash events are complex and driver restraint systems are unique to the motorsport environment. The National Association for Stock Car Auto Racing, Incorporated (NASCAR®) crash and medical datasets provide an opportunity to assess crash statistics and the relationship between crash characteristics and driver injury. Injury risk curves can estimate driver injury risk and can be developed using vehicle incident data recorder information as inputs. These relationships may provide guidance and insight for at-track emergency response, driver triage and treatment protocols.

METHOD

Eight race seasons of crash and medical record data (including Association for the Advancement of Automotive Medicine Abbreviated Injury Scale (AIS) scores) from the Monster Energy NASCAR Cup Series & NASCAR Xfinity Series were processed and analyzed. Multiple logistic regression modeling was used to produce injury risk curves from longitudinal and lateral resultant change in velocity, resultant peak acceleration, principal direction of force and the number of impacts per incident.

RESULTS

2065 Unique IDR data files were matched with 246 cases of driver injury or sub-injury (severity below AIS 1) and 1819 no-injury cases. Multiple logistic regression modeling showed increasing resultant change in velocity, resultant peak acceleration and the number of impacts during a crash event all increase estimated driver injury risk. After accounting for the other predictors in the model, right lateral impacts were found to have a lower estimated injury risk. The model produced an Area Under the Receiver Operating Characteristics curve of 0.80. Across the eight race seasons in this study the overall average resultant change in velocity was 34.4 kph (21.4 mph) and the average resultant peak acceleration was 19.0 G for an average of 258 crashes per season. For 2011 through 2015, full time drivers experienced 134 times more crashes per mile traveled than passenger vehicles, but experienced 9.3 times fewer injuries per crash.

CONCLUSION

Multiple logistic regression was used to estimate AIS 1+ injury only and AIS 1+ with sub-injury risk for motorsport drivers using motorsport-specific crash and medical record databases. The injury risk estimate models can provide future guidance and insight for at-track emergency medical response dispatch immediately following an on-track crash. These models may also inform future driver triage protocols and influence future expenditures on motorsports safety research.

Lumbar Spine Response of Computational Finite Element Models in Multidirectional Spaceflight Landing Conditions

The goals of this study are to compare the lumbar spine response variance between the hybrid III, test device for human occupant restraint (THOR), and global human body models consortium simplified 50th percentile (GHBMC M50-OS) finite element models and evaluate the sensitivity of lumbar spine injury metrics to multidirectional acceleration pulses for spaceflight landing conditions. The hybrid III, THOR, and GHBMC models were positioned in a baseline posture within a generic seat with side guards and a five-point restraint system. Thirteen boundary conditions, which were categorized as loading condition variables and environmental variables, were included in the parametric study using a Latin hypercube design of experiments. Each of the three models underwent 455 simulations for a total of 1365 simulations. The hybrid III and THOR models exhibited similar lumbar compression forces. The average lumbar compression force was 45% higher for hybrid III (2.2 ± 1.5 kN) and 51% higher for THOR (2.0 ± 1.6 kN) compared to GHBMC (1.3 ± 0.9 kN). Compared to hybrid III, THOR sustained an average 64% higher lumbar flexion moment and an average 436% higher lumbar extension moment. The GHBMC model sustained much lower bending moments compared to hybrid III and THOR. Regressions revealed that lumbar spine responses were more sensitive to loading condition variables than environmental variables across all models. This study quantified the intermodel lumbar spine response variations and sensitivity between hybrid III, THOR, and GHBMC. Results improve the understanding of lumbar spine response in spaceflight landings.

Head injury metric response in finite element ATDs and a human body model in multidirectional loading regimes

Objective: The objective was to quantify head injury metric sensitivity of the 50th percentile male Hybrid III, THOR, and Global Human Body Models Consortium simplified occupant (GHBMC M50-OS) to changes in loading conditions in loading regimes that may be experienced by occupants of spaceflight vehicles or highly autonomous vehicles (HAVs) with nontraditional seating configurations.Methods: A Latin hypercube (LHD) design of experiments (DOE) was employed to develop boundary conditions for 455 unique acceleration profiles. Three previously validated finite element (FE) models of the Hybrid III anthropomorphic test device (ATD), THOR ATD, and GHBMC M50-OS were positioned in an upright 90°-90°-90° seat and with a 5-point belt. Acceleration pulses were applied to each of the three occupants in the ± X, +Y, and ± Z directions, with peak resultant acceleration magnitudes ranging from 5 to 20 G and times to peak ranging from 32.5 to 120.8 ms with duration 250 ms, resulting in 1,248 simulations. Head injury metrics included peak linear head acceleration, peak rotational head acceleration, head injury criteria (HIC15), and brain injury criteria (BrIC). Injury metrics were regressed against boundary condition parameters using 2nd order multiple polynomial regression, and compared between occupants using matched pairs Wilcoxon signed rank analysis.Results: Across the 416 matched-simulations that reached normal termination with all three models, HIC15 values ranged from 1.0-396.5 (Hybrid III), 1.2-327.9 (THOR), and 0.6-585.6 (GHBMC). BrIC ranged from 0.03-0.95 (Hybrid III), 0.03-1.21 (THOR), and 0.04-0.84 (GHBMC). Wilcoxon signed rank analysis demonstrated significant pairwise differences between each of the three occupant models for head injury metrics. For HIC15, the largest divergence between GHBMC and the ATDs was observed in simulations with components of combined underbody and rear impact loading. The three models performed most similarly with respect to BrIC output when loaded in a frontal direction. Both the GHBMC and the Hybrid III produced lower values of BrIC than the THOR on average, with the differences most pronounced in rear impact loading.Conclusion: In conclusion, observed differences between the occupant models' head injury metric output were quantified. Loading direction had a large effect on metric outcome and metric comparability across models, with frontal and rear impacts with low vertical acceleration tending to be the most similar. One explanation for these differences could be the differences in neck stiffness between the models that allowed more rotation in the GHBMC and THOR. Care should be taken when using ATDs as human volunteer surrogates in these low energy events.

Machine Learning for Automatic Paraspinous Muscle Area and Attenuation Measures on Low-Dose Chest CT Scans

RATIONALE AND OBJECTIVES

To develop and evaluate an automated machine learning (ML) algorithm for segmenting the paraspinous muscles on chest computed tomography (CT) scans to evaluate for presence of sarcopenia.

MATERIALS AND METHODS

A convolutional neural network based on the U-Net architecture was trained to perform muscle segmentation on a dataset of 1875 single slice CT images and was tested on 209 CT images of participants in the National Lung Screening Trial. Low-dose, noncontrast CT examinations were obtained at 33 clinical sites, using scanners from four manufacturers. The study participants had a mean age of 71.6 years (range, 70-74 years). Ground truth was obtained by manually segmenting the left paraspinous muscle at the level of the T12 vertebra. Muscle cross-sectional area (CSA) and muscle attenuation (MA) were recorded. Comparison between the ML algorithm and ground truth measures of muscle CSA and MA were obtained using Dice similarity coefficients and Pearson correlations.

RESULTS

Compared to ground truth segmentation, the ML algorithm achieved median (standard deviation) Dice scores of 0.94 (0.04) in the test set. Mean (SD) muscle CSA was 14.3 (3.6) cm² for ground truth and 13.7 (3.5) cm² for ML segmentation. Mean (SD) MA was 41.6 (7.6) Hounsfield units (HU) for ground truth and 43.5 (7.9) HU for ML segmentation. There was high correlation between ML algorithm and ground truth for muscle CSA (r² = 0.86; p < 0.0001) and MA (r² = 0.95; p < 0.0001).

CONCLUSION

The ML algorithm for measurement of paraspinous muscles compared favorably to manual ground truth measurements in the NLST. The algorithm generalized well to a heterogeneous set of low-dose CT images and may be capable of automated quantification of muscle metrics to screen for sarcopenia on routine chest CT examinations.

Automated Segmentation of Tissues Using CT and MRI: A Systematic Review

RATIONALE AND OBJECTIVES

The automated segmentation of organs and tissues throughout the body using computed tomography and magnetic resonance imaging has been rapidly increasing. Research into many medical conditions has benefited greatly from these approaches by allowing the development of more rapid and reproducible quantitative imaging markers. These markers have been used to help diagnose disease, determine prognosis, select patients for therapy, and follow responses to therapy. Because some of these tools are now transitioning from research environments to clinical practice, it is important for radiologists to become familiar with various methods used for automated segmentation.

MATERIALS AND METHODS

The Radiology Research Alliance of the Association of University Radiologists convened an Automated Segmentation Task Force to conduct a systematic review of the peer-reviewed literature on this topic.

RESULTS

The systematic review presented here includes 408 studies and discusses various approaches to automated segmentation using computed tomography and magnetic resonance imaging for neurologic, thoracic, abdominal, musculoskeletal, and breast imaging applications.

CONCLUSION

These insights should help prepare radiologists to better evaluate automated segmentation tools and apply them not only to research, but eventually to clinical practice.

AUTOMATED MEASUREMENT OF MUSCLE DENSITY ON COMPUTED TOMOGRAPHY (CT) PREDICTS ALL-CAUSE MORTALITY IN OLDER ADULTS

The purpose was to examine the association of paraspinous muscle density (CT surrogate of myosteatosis) with all-cause mortality in 6803 men and 4558 women, age 60-69 years (mean age 63.6) in the National Lung Screening Trial. Our fully-automated machine learning algorithm: 1) selected the appropriate CT series, 2) chose a single CT image at the level of T12 vertebra, 3) segmented the left paraspinous muscle, and 4) recorded the muscle density in Hounsfield Units (HU). Association between baseline muscle density and all-cause mortality was determined using Cox proportional hazards models, adjusted for age, race, body mass index, pack years of smoking, and presence of diabetes, lung disease, cardiovascular disease, and cancer at enrollment. After a mean 6.44 ± 1.06 years of follow-up, 635 (9.33%) men and 265 (5.81%) women died. In men, lower muscle density on baseline CT examinations was associated with increased all-cause mortality (HR per SD = 0.90; CI = 0.83, 0.99; p=0.03). Each standard deviation (7.8 HU) decrease in muscle density was associated with a 10% increase in mortality. In women, the association did not reach significance.

Sarcopenia and osteosarcopenia in seriously injured motor vehicle crash occupants

Objective: The objective of this study was to examine the prevalence of sarcopenia (low muscle mass) and osteosarcopenia (low bone density and muscle mass) in older motor vehicle crash (MVC) occupants and the relationship of these musculoskeletal conditions with age, sex, and injury.Methods: Sarcopenia and osteopenia was assessed from abdominal computed tomography (CT) scans of 61 seriously injured MVC occupants over age 50 in the Crash Injury Research and Engineering Network (CIREN) database.Results: The prevalence was 43% for sarcopenia, 25% for osteopenia, and 15% for osteosarcopenia in the CIREN occupants. The Injury Severity Score (ISS) was higher in those with only sarcopenia (mean ± SE = 22.4 ± 2.3), followed by those with osteosarcopenia (17.9 ± 2.4) and only osteopenia (12.8 ± 1.5). More total fractures were observed in occupants with sarcopenia alone (7.6 ± 1.5) or osteosarcopenia (7.0 ± 2.1) compared to nonsarcopenic occupants with osteopenia (4.0 ± 2.5).Conclusions: Sarcopenia and osteosarcopenia may be associated with more serious injuries and fractures in MVCs.

Cardiothoracic Morphology Measures in Heart Failure Patients to Inform Device Designs

PURPOSE

Approximately 5.7 million people in the US are affected by congestive heart failure. This study aimed to quantitatively evaluate cardiothoracic morphology and variability within a cohort of heart failure patients for the purpose of optimally engineering cardiac devices for a variety of heart failure patients.

METHODS

Co-registered cardiac-gated and non-gated chest computed tomography (CT) scans were analyzed from 20 heart failure patients (12 males; 8 females) who were primarily older adults (79.5 ± 8.8 years). Twelve cardiothoracic measurements were collected and compared to study sex and left ventricular (LV) ejection fraction (EF) type differences in cardiothoracic morphology.

RESULTS

Four measures were significantly greater in males compared to females: LV long-axis length, LV end diastolic diameter (LVEDD) at 50% length of the LV long-axis, the minimal distance between the sternum and heart, and the angle between the LV long-axis and coronal plane. Four measures were significantly greater in patients with reduced EF compared to preserved LV: LV long-axis length, LVEDD at 50% length of the LV long-axis, left ventricular volume normalized by body surface area, and the angle between the mitral valve plane and LV long-axis.

CONCLUSIONS

These cardiothoracic morphology measurements are important to consider in the design of cardiac devices for heart failure management (e.g. cardiac pacemakers, ventricular assist devices, and implantable defibrillators), since morphology differs by sex and ejection fraction.

Age-based differences in the disability of extremity injuries in pediatric and adult occupants

Objective: The objective was to develop a disability-based metric for motor vehicle crash (MVC) upper and lower extremity injuries and compare functional outcomes between children and adults.Methods: Disability risk (DR) was quantified using Functional Independence Measure (FIM) scores within the National Trauma Data Bank-Research Data System for the top 95% most frequently occurring Abbreviated Injury Scale (AIS) 3 extremity injuries (22 unique injuries). Pediatric (7-18 years), young adult (19-45 years), middle-aged (46-65 years), and older adult (66+ years) MVC occupants with an FIM score and at least one of the 22 extremity injuries were included. DR was calculated for each injury as the proportion of occupants who were disabled of those sustaining the injury. A maximum AIS-adjusted disability risk (DR_MAIS) was also calculated for each injury, excluding occupants with AIS 4+ co-injuries.Results: Locomotion impairment was the most frequent disability type across all ages. DR and DR_MAIS of the extremity injuries ranged from 0.06 to 1.00 (6%-100% disability risk). Disability risk increased with age, with DR_MAIS increasing from 25.9% ± 8.6% (mean ± SD) in pediatric subjects to 30.4% ± 6.3% in young adults, 39.5% ± 6.6% in middle-aged adults, and 60.5 ± 13.3% in older adults. DR_MAIS for upper extremity fractures differed significantly between age groups, with higher disability in older adults, followed by middle-aged adults. DR_MAIS for pelvis, hip, shaft, knee, and other lower extremity fractures differed significantly between age groups, with older adult DR_MAIS being significantly higher for each fracture type. DR_MAIS for hip and lower extremity shaft fractures was also significantly higher in middle-aged occupants compared to pediatric and young adult occupants. The maximum AIS-adjusted mortality risk (MR_MAIS, proportion of fatalities among occupants sustaining an MAIS 3 injury) was not correlated with DR_MAIS for extremity injuries in pediatric, young adult, middle-aged, and older adult occupants (all R² < 0.01). Disability associated with each extremity injury was higher than mortality risk.Conclusions: Older adults had significantly greater disability for MVC extremity injuries. Lower disability rates in children may stem from their increased physiological capacity for bone healing and relative lack of bone disease. The disability metrics developed can supplement AIS and other severity-based metrics by accounting for the age-specific functional implications of MVC extremity injuries.

Neck Muscle Changes Following Long-Duration Spaceflight

The effects of long-duration spaceflight on crewmember neck musculature have not been adequately studied. The purpose of this study was to evaluate the changes in the neck musculature on pre-flight and post-flight magnetic resonance imaging (MRI) examinations of six crewmembers on 4- to 6-month missions equipped with the advanced resistive exercise device (aRED). The MRI images were resliced to remove variations in spinal curvature, the cross-sectional area (CSA), and muscle fat infiltration (MFI) of neck musculature at the C1-C2, C4-C5, C7-T1, and T1-T2 intervertebral disc levels were measured bilaterally. Percent changes in the neck muscle CSA and fatty infiltration following spaceflight were calculated, and mixed models were used to assess significance of these changes. Crewmembers on missions equipped with the aRED experienced an average 25.1% increase in CSA for the trapezius muscle at C6-C7, an average 11.5% increase in CSA for the semispinalis capitis muscle at C4-C5, an average 9.0% increase in CSA for the sternocleidomastoid muscle at C4-C5, and an average 23.1% increase in CSA for the rhomboid minor at T1-T2. There were no significant changes in the CSA of the levator scapulae, splenius capitis, rectus capitis posterior major, scalenus anterior, scalenus posterior, scalenus medius, longissimus capitis, or obliquus capitis inferior muscles at the locations measured. None of the muscles analyzed experienced statistically significant changes in fatty infiltration with spaceflight. Our study indicates that long-duration spaceflight conditions are associated with preservation of CSA in most neck muscles and significant increases in the CSAs of the trapezius, semispinalis capitis, sternocleidomastoid, and rhomboid minor muscles. This may indicate that cervical muscles are not subjected to the same degradative effects microgravity imparts on the majority of muscles.

Comparing rib cortical thickness measurements from computed tomography (CT) and Micro-CT

BACKGROUND

The objective of this study was to compare cortical thickness of rib specimens scanned with clinical computed tomography (clinical-CT) at 0.5 and 1.0 mm slice thickness versus micro-CT at 0.05 mm slice thickness. Cortical thickness variation and accuracy was explored by anatomical region (anterior vs. lateral) and cross-sectional quadrants (superior, interior, inferior, and exterior).

METHODS

A validated cortical thickness algorithm was applied to clinical-CT and micro-CT scans of 17 rib specimens from six male post mortem human subjects aged 42-81 years. Each rib specimen was segmented and the thickness measurements were partitioned into cross-sectional quadrants in the anterior and lateral regions of the rib. Within each rib quadrant, the following were calculated: average thickness ± standard deviation, mean thickness difference between clinical-CT and micro-CT, and a thickness ratio between clinical-CT and micro-CT. Correlations from linear regression and paired-t tests were determined for paired clinical-CT and micro-CT results.

RESULTS

On average, the 0.5 mm clinical-CT underestimated the micro-CT thickness by 0.005 mm, while the 1.0 mm clinical-CT overestimated the micro-CT thickness by 0.149 mm. Thickness derived from 0.5 mm clinical-CT showed greater significant linear correlations (p < 0.05) with micro-CT thickness compared to 1.0 mm clinical-CT.

CONCLUSIONS

The small mean differences and thickness ratios near 1 show validation for the cortical thickness algorithm when applied to rib clinical-CT scans. Using clinical-CT scans as way to accurately measure rib cortical thickness offers a non-invasive way to analyze millions of CT scans collected each year from males and females of all ages.

Lumbopelvic Muscle Changes Following Long-Duration Spaceflight

Long-duration spaceflight has been shown to negatively affect the lumbopelvic muscles of crewmembers. Through analysis of computed tomography scans of crewmembers on 4- to 6-month missions equipped with the interim resistive exercise device, the structural deterioration of the psoas, quadratus lumborum, and paraspinal muscles was assessed. Computed tomography scans of 16 crewmembers were collected before and after long-duration spaceflight. The volume and attenuation of lumbar musculature at the L2 vertebral level were measured. Percent changes in the lumbopelvic muscle volume and attenuation (indicative of myosteatosis, or intermuscular fat infiltration) following spaceflight were calculated. Due to historical studies demonstrating only decreases in the muscles assessed, a one-sample t test was performed to determine if these decreases persist in more recent flight conditions. Crewmembers on interim resistive exercise device-equipped missions experienced an average 9.5% (2.0% SE) decrease in volume and 6.0% (1.5% SE) decrease in attenuation in the quadratus lumborum muscles and an average 5.3% (1.0% SE) decrease in volume and 5.3% (1.6% SE) decrease in attenuation in the paraspinal muscles. Crewmembers experienced no significant changes in psoas muscle volume or attenuation. No significant changes in intermuscular adipose tissue volume or attenuation were found in any muscles. Long-duration spaceflight was associated with preservation of psoas muscle volume and attenuation and significant decreases in quadratus lumborum and paraspinal muscle volume and attenuation.

Prediction of lumbar vertebral body compressive strength of overweight and obese older adults using morphed subject-specific finite-element models to evaluate the effects of weight loss

BACKGROUND

Diet and exercise can promote weight loss in older adults; however, there is potential to increase fracture risk due to loss of bone mineral density (BMD) known to accompany weight loss. Weight loss effects on measures of bone quality and strength are currently unknown.

AIMS

The purpose of this study is to develop subject-specific finite-element (FE) models of the lumbar spine and study the effect of intentional weight loss on bone strength in a pilot data set.

METHODS

Computed tomography (CT) scans of the lumbar spine of 30 overweight and obese (mean BMI = 29.7 ± 3.9 kg/m²), older adults (mean age = 65.9 ± 4.6 years) undergoing an 18-month intentional weight loss intervention were obtained at baseline and post-intervention. Measures of volumetric BMD (vBMD) and variable cortical thickness were derived from each subject CT scan. Development of the subject-specific FE models of the lumbar spine involved model morphing techniques to accelerate the development of the models. vBMD-derived material properties and cortical thickness measures were directly mapped to baseline and post-intervention models. Bone strength was estimated through simulation of a quasi-static uniaxial compression test.

RESULTS

From baseline to 18-month post-weight loss intervention, there were statistically significant decreases in estimated bone strength (6.5% decrease; p < 0.05). Adjusting for baseline bone measures and gender revealed no statistically significant correlations between weight change and change in vBMD, cortical thickness, or bone strength.

CONCLUSION

Integration of CT-based measures and FE models with conventional areal BMD can improve the understanding of the effects of intentional weight loss on bone health.

Effect of a hypocaloric, nutritionally complete, higher-protein meal plan on bone density and quality in older adults with obesity: a randomized trial

Background

Dietary protein and micronutrients are important to the maintenance of bone health and may be an effective countermeasure to weight-loss-associated bone loss.

Objectives

We aimed to determine the effect of a 6-mo hypocaloric, nutritionally complete, higher-protein meal plan on change in bone density and quality as compared with weight stability in older adults using a randomized post-test design. We hypothesized that participants randomly assigned to this meal plan would maintain similar bone density and quality to weight-stable controls, despite significant reductions in body mass.

Methods

Ninety-six older adults (aged 70.3 ± 3.7 y, 74% women, 27% African American) with obesity [body mass index (kg/m2): 35.4 ± 3.3] were randomly assigned to a 6-mo hypocaloric, nutritionally complete, higher-protein meal plan targeting ≥1.0 g protein · kg body weight-1 · d-1 [weight-loss (WL) group; n = 47] or to a weight-stability (WS) group targeting 0.8 g protein · kg body weight-1 · d-1, the current Recommended Dietary Allowance (n = 49). The primary outcome was total hip bone mineral density (BMD), with femoral neck BMD, lumbar spine BMD, and lumbar spine trabecular bone score (TBS) as secondary outcomes, all assessed at baseline and 3 and 6 mo with dual-energy X-ray absorptiometry.

Results

Baseline total hip, femoral neck, and lumbar spine BMDs were 1.016 ± 0.160, 0.941 ± 0.142, and 1.287 ± 0.246 g/cm2, respectively; lumbar TBS was 1.398 ± 0.109. Despite significant weight loss achieved in the WL group (6.6 ± 0.4 kg; 8.6% ± 0.4% of baseline weight), 6-mo regional BMD estimates were similar to those in the WS group (all P > 0.05). Lumbar spine TBS significantly increased at 6 mo in the WL group (mean: 1.421; 95% CI: 1.401, 1.441) compared with the WS group (1.390: 95% CI: 1.370, 1.409; P = 0.02).

Conclusions

Older adults following a hypocaloric, nutritionally complete, higher-protein meal plan maintained similar bone density and quality to weight-stable controls. Our data suggest that adherence to this diet does not produce loss of hip and spine bone density in older adults and may improve bone quality. This trial was registered at clinicaltrials.gov as NCT02730988.

Associations between upper extremity injury patterns in side impact motor vehicle collisions with occupant and crash characteristics

INTRODUCTION

Side impact motor vehicle collisions (MVC) represent a significant burden of mortality and morbidity caused by automotive injury within the United States. The objective of this study was to evaluate the relationship between upper extremity (UE) injury patterns and contact sources in side impact MVC with occupant and crash variables.

METHODS

Crash Injury Research and Engineering Network data obtained from 1998 to 2012 were used to evaluate UE injuries in side impact crashes. First row drivers and passengers that were at least 16 years old with complete crash information were included. Side impact crashes were defined to have an area of deformation to the side of the vehicle and a principal direction of force between 60° and 120° or 240° and 300°. Injuries were stratified by type, anatomic location, and Abbreviated Injury Scale (AIS) severity. Occupant variables included age, sex, height, weight, body mass index, and Injury Severity Score. Vehicle and crash variables included in the analysis were change in vehicle velocity at the time of impact, maximum door intrusion, maximum B-pillar intrusion, seat track position, belt use, vehicle type, impact type, and injury source. Statistical analysis of the UE injury data included descriptive statistics, linear regression analyses with occupant variables, and logistic regression analyses with vehicle and crash variables.

RESULTS

There were 903 UE injuries among 408 case occupants. The most common injury type was soft tissue injury (72.5%). The majority of fractures were proximal to and including the humerus (70.3%) with the clavicle being the most common fracture location (N = 89). AIS 2+ UE injuries were associated with a significantly higher mean occupant Injury Severity Score than AIS 1 UE injuries (p = 0.01). Contact with the door was the leading cause of UE injury (34.2%). The odds (OR [95% confidence interval], p-value) of an AIS 2+ UE injury due to contact with the B-pillar (5.3 [3.1, 9.1], <0.0001), door (1.9 [1.3, 2.7], 0.0006), and steering wheel/assembly (2.7 [1.1, 6.3], 0.03) were significantly higher than all other injury sources combined. Scapula fractures were significantly associated with rearward seat track positions (1.46 [1.04, 2.05], 0.03).

CONCLUSIONS

This study provides insight into UE injury patterns in side impact MVC. The clavicle was the most common UE fracture location. Contact with the door resulted in the highest number of UE injuries and the B-pillar resulted in the most severe injuries. Additionally, exposure to greater B-pillar intrusion was associated with increased odds of scapula and clavicle fractures in side impacts.

Effect of Exercise Modality During Weight Loss on Bone Health in Older Adults With Obesity and Cardiovascular Disease or Metabolic Syndrome: A Randomized Controlled Trial

The objective of this study was to determine the ability of either aerobic or resistance training to counter weight-loss-associated bone loss in older adults. There were 187 older adults (67 years, 70% women, 64% white) with obesity (BMI = 34.5 ± 3.7 kg/m² ) and cardiovascular disease and/or metabolic syndrome who were randomized to participate in an 18-month, community-based trial, with a follow-up assessment at 30 months. Intervention arms included: weight loss alone (WL; 7% to 10% baseline weight), WL plus aerobic training (WL + AT), and WL plus resistance training (WL + RT), as well as DXA-acquired total hip, femoral neck, and lumbar spine areal bone mineral density (aBMD), and trabecular bone score (TBS). Biomarkers of bone turnover (procollagen type 1 N-terminal propeptide, C-terminal telopeptide of type 1 collagen) were measured at baseline, 6, 18, and 30 (aBMD and TBS only) months. CT-acquired hip and spine volumetric BMD (vBMD), cortical thickness, and bone strength were measured in a subset at baseline (n = 55) and 18 months. Total hip aBMD was reduced by 2% in all groups at 18 months, with a primary analysis showing no significant treatment effects for any DXA, biomarker, or CT outcome. After adjustment for WL and follow-up at 30 months, secondary analyses revealed that total hip [-0.018 (-0.023 to -0.012) g/cm² versus -0.025 (-0.031 to -0.019) g/cm² ; p = 0.05] and femoral neck [-0.01 (-0.009 to 0.008) g/cm² versus -0.011 (-0.020 to -0.002) g/cm² ; p = 0.06] aBMD estimates were modestly attenuated in the WL + RT group compared with the WL group. Additionally, lumbar spine aBMD was increased in the WL [0.015 (0.007 to 0.024) g/cm² ] and the WL + RT [0.009 (0.000 to 0.017) g/cm² ] groups compared with the WL + AT [-0.003 (-0.012 to 0.005)g/cm² ] group; both p ≤ 0.01. Community-based exercise does not prevent bone loss during active WL in older adults; however, adding RT may help minimize long-term hip bone loss. © 2018 American Society for Bone and Mineral Research.

Pelvic and Lower Gastrointestinal Tract Anatomical Characterization of the Average Male

OBJECTIVE

Colorectal surgeons report difficulty in positioning surgical devices in males, particularly those with a narrower pelvis. The objectives of this study were to (1) characterize the anatomy of the pelvis and surrounding soft tissue from magnetic resonance and computed tomography scans from 10 average males (175 cm, 78 kg) and (2) develop a model representing the mean configuration to assess variability.

METHODS

The anatomy was characterized from existing scans using segmentation and registration techniques. Size and shape variation in the pelvis and soft tissue morphology was characterized using the Generalized Procrustes Analysis to compute the mean configuration.

RESULTS

There was considerable variability in volume of the psoas, connective tissue, and pelvis and in surface area of the mesorectum, pelvis, and connective tissue. Subject height was positively correlated with mesorectum surface area (P = .028, R² = 0.47) and pelvis volume ( P = .041, R² = 0.43). The anterior-posterior distance between the inferior pelvic floor muscle and pubic symphysis was positively correlated with subject height ( P = .043, r = 0.65). The angle between the superior mesorectum and sacral promontory was negatively correlated with subject height ( P = .042, r = -0.65). The pelvic inlet was positively correlated with subject weight ( P = .001, r = 0.89).

CONCLUSIONS

There was considerable variability in organ volume and surface area among average males with some correlations to subject height and weight. A physical trainer model created from these data helped surgeons trial and assess device prototypes in a controllable environment.

Validation of a Finite Element 50th Percentile THOR Anthropomorphic Test Device in Multiple Sled Test Configurations

Computational models of anthropomorphic test devices (ATDs) can be used in crash simulations to quantify the injury risks to occupants in both a cost-effective and time-sensitive manner. The purpose of this study was to validate the performance of a 50^th percentile THOR finite element (FE) model against a physical THOR ATD in 11 unique loading scenarios. Physical tests used for validation were performed on a Horizontal Impact Accelerator (HIA) where the peak sled acceleration ranged from 8-20 G and the time to peak acceleration ranged from 40-110 ms. The directions of sled acceleration relative to the THOR model consisted of -GX (frontal impact), +GY (left-sided lateral impact), and +GZ (downward vertical impact) orientations. Simulation responses were compared to physical tests using the CORrelation and Analysis (CORA) method. Using a weighted method, the average response and standard error by direction was +GY (0.83±0.03), -GX (0.80±0.01), and +GZ (0.76±0.03). Qualitative and quantitative results demonstrated the FE model's kinetics and kinematics were sufficiently validated against its counterpart physical model in the tested loading directions.

Opportunistic Screening for Osteoporosis Using Computed Tomography: State of the Art and Argument for Paradigm Shift

PURPOSE OF REVIEW

Osteoporosis is disproportionately common in rheumatology patients. For the past three decades, the diagnosis of osteoporosis has benefited from well-established practice guidelines that emphasized the use of dual x-ray absorptiometry (DXA). Despite these guidelines and the wide availability of DXA, approximately two thirds of eligible patients do not undergo testing. One strategy to improve osteoporosis testing is to employ computed tomography (CT) examinations obtained as part of routine patient care to "opportunistically" screen for osteoporosis, without additional cost or radiation exposure to patients. This review examines the role of opportunistic CT in the evaluation of osteoporosis.

RECENT FINDINGS

Recent evidence suggests that opportunistic measurement of bone attenuation (radiodensity) using CT has sensitivity comparable to DXA. More importantly, such an approach has been shown to predict osteoporotic fractures. The paradigm shift of using CTs obtained for other reasons to opportunistically screen for osteoporosis promises to substantially improve patient care.