Youth sports specialization and musculoskeletal injury: a systematic review of the literature.
OBJECTIVE
Early sports specialization is being seen with increasing frequency in children and adolescents in an attempt to achieve elite performance status. This phenomenon has attracted negative medical and lay media attention due, in part, to the possibility of an increased risk of acute and overuse injuries. The purpose of this study was to systematically review available research on youth sport specialization and musculoskeletal injury.


METHODS
A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for studies evaluating sports specialization and injury rates in participants under age 18. Inclusion criteria were: (1) youth patient population (defined as <18 years of age), (2) peer-reviewed investigation of association(s) between sports specialization and incidence of injury, and (3) original research article (rather than a review, case report, or meta-analysis). Exclusion criteria were: (1) reliance on surrogate measure(s) of sports specialization (eg. hours of participation), (2) language other than English, and (3) not a clinically-based study. Rates of sport specialization, acute and overuse injuries, and frequency of organized training regimens were recorded.


RESULTS
Three studies met final inclusion and exclusion criteria. Of these studies two were retrospective cohort studies and one was a case-control study. All three studies reported an increased risk of overuse injures (OR range: 1.27-4.0; P < 0.05) which varied by sport and anatomic pathology. One study noted an increased rate of withdrawal from tennis matches (OR = 1.55, P < 0.05) in athletes who participated only in tennis compared to multisport athletes who competed in tennis. Based on the consistency of the results from included studies, the strength of recommendation grade for the current evidence against early sports specialization is "B" (recommendation based on limited-quality patient-oriented evidence).


CONCLUSIONS
The primary evidence that currently exists with regard to early sport specialization is scarce, retrospective, and shows only modest associations between early sports specialization and overuse injury. Further prospective research is needed to more definitively determine if early sports specialization in children is associated with increased injury risk.


METHODS
Systematic Review, Level III.
a Department of Orthopaedic Surgery , Boston Children's Hospital , Boston , MA , USA.
Peter D
PD
Fabricant
b School of Medicine, Vanderbilt University , Nashville , TN , USA.
Nikita
N
Lakomkin
c Boston Children's Hospital Sports Medicine , The Micheli Center for Sports Injury Prevention , Waltham , MA , USA.
Dai
D
Sugimoto
a Department of Orthopaedic Surgery , Boston Children's Hospital , Boston , MA , USA.
Frances A
FA
Tepolt
c Boston Children's Hospital Sports Medicine , The Micheli Center for Sports Injury Prevention , Waltham , MA , USA.|d Harvard Medical School , Boston , MA , USA.
Andrea
A
Stracciolini
a Department of Orthopaedic Surgery , Boston Children's Hospital , Boston , MA , USA.|d Harvard Medical School , Boston , MA , USA.
Mininder S
MS
Kocher
D000293:Adolescent; D001265:Athletic Injuries / Q000209:etiology*; D002648:Child; D012090:Cumulative Trauma Disorders / Q000209:etiology; D006801:Humans; D013038:Specialization; D000067009:Youth Sports
Athletics; acute; adolescent; chronic; free play; overuse; pediatric