Modeling Risk for Lower Extremity Musculoskeletal Injury in U.S. Military Academy Cadet Basic Training.

INTRODUCTION: Sport and tactical populations are often impacted by musculoskeletal injury. Many publications have highlighted that risk is correlated with multiple variables. There do not appear to be existing studies that have evaluated a predetermined combination of risk factors that provide a pragmatic model for application in tactical and/or sports settings. PURPOSE: To develop and test the predictive capability of multivariable risk models of lower extremity musculoskeletal injury during cadet basic training at the U.S.Military Academy. MATERIALS AND METHODS: Cadets from the class of 2022 served as the study population. Sex and injury history were collected by questionnaire. Body Mass Index (BMI) and aerobic fitness were calculated during testing in the first week of training. Movement screening was performed using the Landing Error Scoring System during week 1 and cadence was collected using an accelerometer worn throughout initial training. Kaplan-Meier survival curves estimated group differences in time to the first musculoskeletal injury during training. Cox regression was used to estimate hazard ratios (HRs) and Akaike Information Criterion (AIC) was used to compare model fit. RESULTS: Cox modeling using HRs indicated that the following variables were associated with injury risk : Sex, history of injury, Landing Error Scoring System Score Category, and Physical Fitness Test (PT) Run Score. When controlling for sex and history of injury, amodel including aerobic fitness and BMI outperformed the model including movement screening risk and cadence (AIC: 1068.56 vs. 1074.11) and a model containing all variables that were significant in the univariable analysis was the most precise (AIC: 1063.68). CONCLUSIONS: In addition to variables typically collected in this tactical setting (Injury History, BMI, and aerobic fitness), the inclusion of kinematic testing appears to enhance the precision of the risk identification model and will likely continue to be included in screening cadets at greater risk.

Lower Extremity Musculoskeletal Injury in US Military Academy Cadet Basic Training: A Survival Analysis Evaluating Sex, History of Injury, and Body Mass Index.

BACKGROUND: Injury incidence for physically active populations with a high volume of physical load can exceed 79%. There is little existing research focused on timing of injury and how that timing differs based on certain risk factors. PURPOSE/HYPOTHESIS: The purpose of this study was to report both the incidence and timing of lower extremity injuries during cadet basic training. We hypothesized that women, those with a history of injury, and those in underweight and obese body mass index (BMI) categories would sustain lower extremity musculoskeletal injury earlier in the training period than men, those without injury history, and those in the normal-weight BMI category. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Cadets from the class of 2022, arriving in 2018, served as the study population. Baseline information on sex and injury history was collected via questionnaire, and BMI was calculated from height and weight taken during week 1 at the United States Military Academy. Categories were underweight (BMI <20), middleweight (20-29.99), and obese (≥30). Injury surveillance was performed over the first 60 days of training via electronic medical record review and monitoring. Kaplan-Meier survival curves were used to estimate group differences in time to the first musculoskeletal injury. Cox proportional hazard regression was used to estimate hazard ratios (HRs). RESULTS: A total of 595 cadets participated. The cohort was 76.8% male, with 29.9% reporting previous injury history and 93.3% having a BMI between 20 and 30. Overall, 16.3% of cadets (12.3% of male cadets and 29.7% of female cadets) experienced an injury during the follow-up period. Women experienced significantly greater incident injury than did men (P < .001). Separation of survival curves comparing the sexes and injury history occurred at weeks 3 and 4, respectively. Hazards for first musculoskeletal injury were significantly greater for women versus men (HR, 2.63; 95% CI, 1.76-3.94) and for those who reported a history of injury versus no injury history (HR, 1.76; 95% CI, 1.18-2.64). No differences were observed between BMI categories. CONCLUSION: Female cadets and those reporting previous musculoskeletal injury demonstrated a greater hazard of musculoskeletal injury during cadet basic training. This study did not observe an association between BMI and injury.

Use of double leg injury screening to assess single leg biomechanical risk variables.

OBJECTIVES: The purpose of this article was to determine if differences in kinematic and kinetic variables observed in a double-leg screen carried over to a single-leg task. DESIGN: We used a case-control design with grouping based on performance during a double-leg jump landing. SETTING: All participants were selected from a large university setting and testing was performed in a biomechanics laboratory. PARTICIPANTS: Participants were females between 18 and 25 years of age with at least high school varsity experience in one or more of the following sports: soccer, lacrosse, field hockey, rugby, basketball, or team handball. MAIN OUTCOME MEASURES: Primary outcome measures were knee angles in the frontal and sagittal planes as well as vertical ground reaction force (vGRF). RESULTS: There were significant between group differences in peak knee flexion and knee flexion displacement during both the double and single-leg tasks, however between group differences for peak knee valgus and knee valgus displacement noted in the double-leg task were not observed in the single-leg task. vGRF was significantly different in the single-leg task but not the double-leg task. CONCLUSION: A double leg screening may not provide complete identification of risk of injury during sports requiring single leg tasks.

Correction to: The Relationship Between Training Load and Injury in Athletes: A Systematic Review.

"Cox proportional hazards regression models with frailty found no difference in injured vs. unin-jured players with week-to-week changes of < 20, 20-60, and > 60%, controlling for scapular con-trol, isometric rotational and abduction strength, and shoulder range of motion (p value ranges 0.09-0.68).

The Relationship Between Training Load and Injury in Athletes: A Systematic Review.

BACKGROUND: The relationship between training load and musculoskeletal injury is a rapidly advancing area of research in need of an updated systematic review. OBJECTIVE: This systematic review examined the evidence for the relationship between training load and musculoskeletal injury risk in athlete, military, and first responder (i.e. law enforcement, firefighting, rescue service) populations. METHODS: The CINAHL, EMBASE, MEDLINE, SportDISCUS, and SCOPUS databases were searched using a comprehensive strategy. Studies published prior to July 2017 were included if they prospectively examined the relationship between training load and injury risk. Study quality was assessed using the Newcastle-Ottawa Quality Assessment Scale (NOS) and Oxford Centre for Evidence-Based Medicine levels of evidence. A narrative synthesis of findings was conducted. RESULTS: A total of 2047 articles were examined for potential inclusion. Forty-six met the inclusion criteria and 11 known to the authors but not found in the search were added, for a total of 57 articles. Overall, 47 studies had at least partially statistically significant results, demonstrating a relationship between training load and injury risk. Included articles were rated as poor (n = 15), fair (n = 6), and good (n = 36) based on NOS score. Articles assessed as 'good' were considered level 2b evidence on the Oxford Centre for Evidence-Based Medicine Model, and articles assessed as 'fair' or 'poor' were considered level 4 evidence. CONCLUSIONS: Our results demonstrate that the existence of a relationship between training load and injury continues to be well supported in the literature and is strongest for subjective internal training load. The directionality of this relationship appears to depend on the type and timeframe of load measured.

Factors Associated With Injury Among Employees at a U.S. Army Hospital.

The purpose of this study was to investigate injury incidence and factors associated with injury among employees at a large U.S. Army hospital to inform injury prevention planning and health promotion education efforts. Demographics, health behaviors, and injury history were collected by survey from hospital employees between October and December 2014. Descriptive statistics were reported and factors associated with injury were determined using multiple logistic regression. Respondents (380; 56% females, 44% males; 54% active duty military, 45% civilians) reported a prevalence of unhealthy behaviors (e.g., not enough exercise [58%] and poor sleeping habits [49%]). Nearly half of respondents (47%) reported at least one occupational injury in the past 12 months. Leading mechanisms of injuries were repetitive overuse (36%), falls (15%), and single twisting movement/overexertion (14%). Leading activities at the time of injury were physical training (24%), walking/hiking (15%), and lifting or moving objects (11%). Factors associated with injury included active duty military status, less education, tobacco use, overuse of alcohol or drugs, and stress. Health education efforts and materials intended for hospital staff should incorporate identified modifiable injury risk factors (e.g., alcohol and drug use, stress, tobacco use, poor sleep). Injury prevention initiatives should focus on physical training, walking/hiking, and lifting. Establishment of surveillance and routine review of employee injury, illness, and health behavior data are recommended to monitor program effects and collect data necessary to inform future prevention priorities and planning.

Stress Fracture of the Sacrum.

A physical therapist evaluated a 25-year-old male military trainee, who reported 1 week of left hip pain exacerbated by running and sitting cross-legged. At follow-up, the patient reported unchanged hip pain and new left knee pain. Due to potential for multifocal stress injuries outside the visual field of a single MRI, bone scan and single-photon emission computerized tomography were chosen as imaging modalities. Imaging revealed a nondisplaced lateral left-sided sacral stress fracture and left calcaneal stress fracture. J Orthop Sports Phys Ther 2015;45(11):965. doi:10.2519/jospt.2015.0411.