Sports Specialization Is Not Associated With Greater Odds of Previous Injury in Elite Male Youth Soccer Players.

OBJECTIVE: To determine the relationship between sport specialization and previous injury in elite male youth soccer players. DESIGN: Retrospective survey. SETTING: U.S. Soccer Development Academy. PARTICIPANTS: Male youth soccer players (N = 2123). ASSESSMENT OF RISK FACTORS: Sport specialization, weekly training volume, training ratio, and age. MAIN OUTCOME MEASURES: Previous sports-related injury, injury type (traumatic vs overuse), injury severity, and injury location. RESULTS: Of 2099 participants (average age 13.2 ± 1.8 years), 61.7% were specialized in soccer (played soccer >8 mo/yr and no other sports) and 38.3% were nonspecialized (played soccer >8 mo/yr and also played other organized sports). Specialized athletes were older than nonspecialized athletes (13.7 ± 1.9 vs 12.5 ± 1.4, P < 0.0001). Thirty-three percent (690/2099) of athletes reported at least one previous sports-related injury for a total of 765 traumatic injuries and 25 overuse injuries. Distribution of injury type was similar for specialized and nonspecialized athletes. Among athletes with overuse injuries, nonspecialized athletes were more likely to report upper-extremity and trunk overuse injuries than specialized athletes. After accounting for age and weekly training volume, specialized athletes had decreased odds of reporting any previous injury compared with nonspecialized athletes [odds ratio (OR), 0.78; 95% confidence interval (CI), 0.64-0.95], and similar odds of reporting a previous lower-extremity (LE) overuse injury as nonspecialized athletes (OR, 0.70; 95% CI, 0.56-1.1). However, specialized athletes missed more practices due to injury than nonspecialized players [median = 3, interquartile range (IQR) 2-4 vs median = 2, IQR 2-4, P = 0.0003]. CONCLUSIONS: In this national sample of elite, male youth soccer players, after accounting for age and weekly training volume, specialized athletes had decreased odds of reporting any previous injury and similar odds of reporting a previous LE overuse injury as nonspecialized athletes. These data suggest the need for further research to determine whether injury risk related to sports specialization depends on sex, chosen sport, and skill/competitive level.

IS (Idiopathic Scoliosis) etiology: Multifactorial genetic research continues. A systematic review 1950 to 2017.

OBJECTIVE: IS (idiopathic scoliosis) is a common spinal condition occurring in otherwise completely healthy adolescents. The root cause of IS remains unclear. This systematic review will focus on an update of genetic factors and IS etiology. Though it is generally accepted that the condition is not due to a single gene effect, etiology studies continue looking for a root cause including genetic variants. Though susceptibility from multiple genetic components is plausible based on known family history data, the literature remains unclear regarding multifactorial genetic influences. The objective of this study was to critically evaluate the evidence behind genetic causes (not single gene) of IS through a systematic review and strength-of-study analysis of existing genetic and genome-wide association studies (GWAS). We used the protocol of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). METHODS: PubMed was searched for the terms IS, scoliotic, spinal curve, genetic, gene, etiology, polymorphisms. Articles were assessed for risk-of-bias. Level-of-evidence grading was completed via Oxford Centre for Evidence-Based Medicine criteria. The assessment scores factor strength of a study in determining a positive or negative association to a gene etiology. RESULTS: After screening of 36 eligible papers, 8 relevant studies met inclusion criteria at this time, 3 were in favor of a genetic factor for IS, whereas 5 studies were against it. CONCLUSION: Based on the literature analyzed, there is moderate evidence with a low risk-of-bias that does not clarify a genetic cause of IS. The 2 studies in favor of a genetic etiology were completed in homogeneous populations, limiting their generalizability. Relying on a genetic etiology alone for IS may over simplify its multifactorial nature and limit appreciation of other influences.