W. H. Meeuwisse

Complex systems approach for sports injuries: moving from risk factor identification to injury pattern recognition—narrative review and new concept

Injury prediction is one of the most challenging issues in sports and a key component for injury prevention. Sports injuries aetiology investigations have assumed a reductionist view in which a phenomenon has been simplified into units and analysed as the sum of its basic parts and causality has been seen in a linear and unidirectional way. This reductionist approach relies on correlation and regression analyses and, despite the vast effort to predict sports injuries, it has been limited in its ability to successfully identify predictive factors. The majority of human health conditions are complex. In this sense, the multifactorial complex nature of sports injuries arises not from the linear interaction between isolated and predictive factors, but from the complex interaction among a web of determinants. Thus, the aim of this conceptual paper was to propose a complex system model for sports injuries and to demonstrate how the implementation of complex system thinking may allow us to better address the complex nature of the sports injuries aetiology. According to this model, we should identify features that are hallmarks of complex systems, such as the pattern of relationships (interactions) among determinants, the regularities (profiles) that simultaneously characterise and constrain the phenomenon and the emerging pattern that arises from the complex web of determinants. In sports practice, this emerging pattern may be related to injury occurrence or adaptation. This novel view of preventive intervention relies on the identification of regularities or risk profile, moving from risk factors to risk pattern recognition.

Effectiveness of cervical spine stabilisation techniques

Background Proper stabilisation of suspected unstable spine injuries is necessary to prevent (worsen) spinal cord damage. Although the lift-and-slide (L&S) technique has been shown superior to the log-roll (LR) technique to place the body on the spinal board, no studies have yet compared different techniques of manual stabilisation of the c-spine itself. Objective To compare cervical motions that occur when trained professionals perform the Head Squeeze (HS) and Trap Squeeze (TS) c-spine stabilisation techniques. Design Cross-over. Setting and participants 12 experienced therapists. Assessment HS and TS during lift-and-slide (L&S) and LR placement on spinal board, and agitated patient trying to trying to sit up (AGIT-Sit) or rotate his head (AGIT-Rot). Main outcome measurements Peak head motion with respect to initial conditions using inertial measurement units attached to the forehead and trunk of the simulated patient. Comparisons between HS and TS with a priori minimal important difference (MID) of 5° for flexion or extension, and 3° for rotation or lateral flexion. Results Overall, the L&S technique was statistically superior to the LR technique. The only differences to exceed the MID were extension and rotation during LR (HS>TS). In the AGIT-Sit test scenario, differences in motion exceeded MID (HS>TS) for flexion, rotation and lateral flexion. In the AGIT-Rot scenario, differences in motion exceeded MID for rotation only (HS>TS). There was similar inter-trial variability of motion for HS and TS during L&S and LR, but significantly more variability with HS compared to TS in the agitated patient. Conclusion The L&S is preferable to the LR when possible for minimizing unwanted c-spine motion. There is little overall difference between HS and TS in a cooperative patient. When a patient is confused and trying to move, the HS is much worse than the TS at minimizing c-spine motion.

Examining the effect of the injury definition on risk factor analysis in circus artists

A secondary data analysis of a prospective cohort study was conducted to explore how different definitions of injury affect the results of risk factor analyses. Modern circus artists (n=1281) were followed for 828 547 performances over a period of 49 months (2004–2008). A univariate risk factor analysis (age, sex, nationality, artist role) estimating incidence rate ratios (IRR) with 95% confidence intervals (95% CI) was conducted using three injury definitions: (1) medical attention injuries, (2) time‐loss injuries resulting in ≥1 missed performances (TL‐1) and (3) time‐loss injuries resulting in >15 missed performances (TL‐15). Results of the risk factor analysis were dependent on the injury definition. Sex (females to male; IRR=1.13, 95% CI; 1.02–1.25) and age over 30 (<20 years to >30 years; IRR=1.37, 95% CI; 1.07–1.79) were risk factors for medical attention injuries only. Risk of injury for Europeans compared with North Americans was higher for TL‐1 and TL‐15 injuries compared with medical attention injuries. Finally, non‐sudden load artists (low‐impact acts) were less likely than sudden load artists (high‐impact acts) to have TL‐1 injuries, but the risk of medical attention injuries was similar. The choice of injury definition can have effects on the magnitude and direction of risk factor analyses.

Are pre-season reports of neck pain, dizziness and/or headaches risk factors for concussion in male youth ice hockey players?

Background Concussion is a commonly encountered injury associated with potential long-term sequelae. No previous studies have evaluated dizziness, neck pain and headache as potential risk factors for concussion. Objective The objective of this study is to determine the risk of concussion in male youth hockey players with preseason reports of neck pain, headaches and dizziness. Design This study is a secondary data analysis of a prospective cohort study examining the risk of injury associated with body checking among paediatric ice hockey players. Setting Youth ice hockey in Alberta and Quebec, Canada. Participants A total of 3902 11–14 year old males from 282 teams participated. Assessment of risk factors Each participant completed a pre-season baseline demographic and injury history questionnaire. Preseason reports of neck pain, headache or dizziness were documented on the Sport Concussion Assessment Tool. Main outcome measurements Diagnosed concussions were recorded during the season of play via a previously validated, prospective injury surveillance system. Results A total of 178 concussions occurred during the studies, with 11 players sustaining two concussions. Incidence rate ratios were calculated using Poisson regression, adjusted for exposure hours, cluster by team and potential covariates. Dizziness was not a significant predictor of concussion. Individuals reporting a headache or neck pain at the start of the season were 1.48 (95% CI 1.02 to 2.14) and 1.69 (95% CI 1.16 to 2.44) times more likely to suffer a concussion during the season than those not reporting these symptoms. Individuals reporting any two of dizziness, headache and neck pain were 1.99 (95% CI 1.20 to 3.32) times more likely to sustain a concussion. Conclusion Male youth athletes reporting headache or neck pain at baseline were at an increased risk of concussion during the season. From an injury prevention perspective, baseline testing may aid in identifying individuals at a higher risk for concussion.

DO RISK FACTORS DIFFER FOR CONCUSSION AND PROLONGED RECOVERY FOLLOWING CONCUSSION IN ELITE YOUTH ICE HOCKEY PLAYERS

Background Pediatric concussion risk factor identification will facilitate targeted injury prevention strategy development. Objective To examine risk factors for concussion and prolonged recovery amongst elite youth ice hockey players. Design Cohort study. Setting Community ice rinks and sport medicine clinic (2011/12 season). Participants Male and female elite Bantam (13–14 years) and Midget (15-17 years) ice hockey players (n=780). Assessment of risk factors Baseline age group, sex, previous concussion history and SCAT2 component scores [Total Symptom Score (TSS), Balance Error Score (BES) and Standardized Assessment of Concussion (SAC) score] were evaluated. Main outcome measurements Players with a suspected concussion were referred to a sport medicine physician by team therapists/trainers (n=137). Concussions with time loss of >10 days were defined as prolonged recovery. Results Concussion incidence rate ratios (IRR) were estimated using multivariate (concussion) and univariate (prolonged recovery) Poisson regression analyses (cluster and exposure hours adjusted). Males were at greater risk than females [IRR=1.44 (95% CI: 1.09–1.90)]. In females with no concussion history, Bantam players were at greater risk than Midget players [IRR=4.04 (95% CI: 1.24–13.19)]. In Midget players, those with a history of concussion were at greater risk than those with no concussion history [IRR=2.68 (95% CI: 1.61–4.46)]. Players with baseline TSS in the lowest 25th %ile were at greater risk of concussion [IRR=1.50 (95% CI: 1.03–2.18)] and prolonged recovery [IRR=1.88 (95% CI: 1.18–2.99)]. Players with a history of concussion were at increased risk for prolonged recovery [IRR=2.02 (95% CI: 1.29–3.16)]. SAC and BES were not risk factors. Conclusions Age group, sex, previous concussion history, and baseline symptom reporting affected the risk of concussion and prolonged recovery in elite youth ice hockey players. This study will inform the development of youth sport concussion prevention strategies.

RISK FACTORS FOR BODY REGION SPECIFIC INJURIES IN SKIERS AND SNOWBOARDERS

Background Little is known about risk factors (e.g., wrist guards, binding adjustment, equipment ownership) for body region specific skiing/snowboarding injuries. Objective Identify risk factors for body region specific injuries and severe injuries in skiers/snowboarders. Design Case-control study using emergency department (ED) interviews, ski patrol Accident Report Forms (ARF), and ski area interviews. Severe injury cases presented to the ED. Non-severe injury cases presented to the ski patrol. Controls were uninjured skiers/snowboarders. Setting An urban ski area and 2 EDs in Alberta, Canada. Participants Injured skiers/snowboarders who saw the ski patrol (n=552) or went to one of the study EDs (n=192). Controls were interviewed at the ski area (n=914). Risk factor assessment Risk factor data were collected by interview and from ARFs. Injury outcomes were determined from the ED chart or ARF. Main outcome measurements Body region categories were: lower extremities, upper extremities, trunk, and head/neck. Odds ratios (OR) with 95% confidence intervals (CI) were calculated for each body region by case group. Intrinsic risk factors (age, sex, activity, ability) will be included in the models. Results Preliminary results for non-severe cases indicate that the odds of injury for all body regions were lower for those 12+ years old compared with younger participants (OR range 0.07; 95% CI 0.04–0.11 to 0.42; 95% CI 0.24–0.73) and higher for beginners (OR range 1.79; 95% CI 1.01–3.15 to 4.97; 95% CI 2.97–8.32). Overcast weather reduced the odds of any injury (OR range 0.06; 95% CI 0.02–0.18 to 0.44; 95% CI 0.2–0.98), as did increased run difficulty (OR range 0.06; 95% CI 0.02–0.17 to 0.19; 95% CI 0.0–0.54). Skiers had lower odds of upper body injury (ARF OR 0.27; 95% CI 0.2–0.38 & ED OR 0.33; 95% CI 0.21–0.51) compared with snowboarders. Conclusions These results will inform the development of an injury prevention program for skiers/snowboarders targeting modifiable risk factors.

THE IMPACT OF CONCUSSION ON CARDIAC AUTONOMIC FUNCTION: A SYSTEMATIC REVIEW OF EVIDENCE FOR RECOVERY AND PREVENTION

Background Concussions can negatively impact cognitive, behavioural, and physiological function. The current standard of care does not account for the physiological impact of concussion. Cardiac autonomic function (CAF) is responsive to changes in physical and cognitive exertion in healthy populations. The influence of concussion on CAF is not well understood. Objective To evaluate the evidence regarding the effect of concussion on cardiac autonomic function. Design Systematic Review. Setting Databases [Medline, SportDiscus, HealthSTAR, PsycINFO, Web of Science, CINAHL, Cochrane Central Register of Controlled Trials, EMBASE, PubMed and ProQuest, Web of Science and Google Scholar] were systematically searched using keywords and MeSH terms. Sample Inclusion criteria: original research, available in English, included participants with concussion or mild traumatic brain injury (mTBI) and had a comparison group. Studies of humans (greater than 6 years old) and animals were included. Ten articles were identified for critical appraisal (six cohort studies, four cross-sectional). Independent variable Diagnosis of a concussion or mTBI. Main outcome measurements Heart rate (HR) and/or heart rate variability (HRV). Critical appraisal was conducted using the Downs and Black criteria. Results There is conflicting evidence regarding CAF at rest following concussion/mTBI. There is evidence of elevated HR and reduced HRV with low intensity, steady-state exercise up to 10 days following concussion. No significant difference in HRV was found during isometric handgrip testing following concussion. The validity of current literature is limited by small sample sizes, lack of female or pediatric participants, varying methodologies and lack of follow-up. No studies evaluating CAF during cognitive exertion following concussion were found. Conclusions There is evidence to suggest that CAF is altered during physical activity following concussion. The limitations in available literature highlight the need further research. Understanding the effect of concussion on CAF will contribute to the development of more comprehensive concussion management and prevention strategies.

An overview of interventions designed to reduce risk factors for sport injury

Background While physical activity is associated with an overall reduction in mortality, morbidity and an improved quality of life, it also increases the risk of injury and illness. Objective To identify gaps in the literature with respect to interventions designed to reduce risk factors for sport injury. Design Review. Databases PubMed, Cinahl, Web of Science, Embase, and Sports Discus were searched. Setting All ages, sex, levels of competition and Olympic sports were included. Main outcome measurement Pattern of publications over time stratified by study design, intervention type, sport and anatomic site. Results Only 144 of 2525 articles retrieved by the search strategy met the inclusion criteria. Cross-over study designs increased by 175% since the late 1980s until 2005 but have declined 32% since. Randomised controlled trial (RCT) study designs increased by 650% since the early 1990s. Protective equipment was the focus of 61.8% of the studies and training the remaining 35.4%. Equipment research studied stability devices (83.1%) and attenuating devices (13.5%) while training research studied balance and coordination (54.9%), strength and power (43.1%) and stretching (15.7%). Almost 92.1% of the studies were of the lower extremity and 78.1% were of the joint (non-bone)-ligament type. 57.5% of the reports studied contact sports, 24.2% collision, and 25.75% non-contact sports. Conclusion We were surprised to find only 144 publications examining interventions designed to reduce risk factors for sport injury. The decrease in cross-over study design and increase in RCTs indicate a shift in research focus. Most notable was the finding that studies using equipment interventions have been decreasing since 2000 (35% decline) while those using training interventions have been increasing (213% increase).

Re-defining normal: bone mineral density in elite female athletes

Background College age female athletes are susceptible to decreased bone mineral density (BMD) which puts them at an elevated risk for poor bone health in the future. Objective The primary purpose of this study was to compare site-specific and total body BMD of college-age female athletes across sports of varying impact level. Secondary objectives included (1) evaluating the relationship between BMD and menstrual, family bone health, and personal bone health histories; (2) to determine the best clinical predictors of BMD in this population. Design Cross-sectional. Setting NCAA Division I female athletes screened at university sports medicine centre. Participants 265 (20.1±1.19 years, 66.5±10.9 kg, 1.7±0.09 m) college-age female athletes from 14 different sporting teams. Interventions Personal and family health questionnaire, Total Body (TB), anteroposterior Spine (APS), Dual Femur (DF) BMD and Body Composition scans using GE Lunar iDXA. Main outcome measurements Athletes were separated into three sport impact categories. BMD measurements were compared across the impact levels. Both stepwise regression and classification and regression tree analysis were conducted to determine significant predictors of BMD. Results Athletes participating in low and moderate impact sports had significantly lower TB and site-specific BMD values when compared to high impact athletes (TB: High=1.24, Mod=1.18, Low=1.15; APS High=1.33, Mod=1.25, Low=1.21; DF High=1.25, Mod=1.12, Low=1.11). The BMD values for each secondary exposure were lower in those with history of abnormal menses (TB-1.19, APS- 1.24, DF- 1.17), previous stress fracture/reaction (TB-1.19, APS- 1.27, DF- 1.17), and poor family bone health (TB-1.18, APS- 1.26, DF- 1.16). Classification and regression trees (CART) analysis shows highest TB mean BMD was found in high impact athletes with LBM>50.9 kg. Conclusion There is an ordinal relationship between sport impact level and BMD. Using CART analysis, gynaecological age, impact level and LBM are the best predictors of mean BMD.