Anterior cruciate ligament (ACL) lesions in adolescents represent a serious concern for the physician. The increased involvement of children and adolescents in organized sports beginning at an early age raises concern regarding risk and severity of sports injury. Inevitably with increased participation and training come an increasing number of sports injuries. Three types of youth sports injury, anterior cruciate ligament (ACL) injury, concussion, and physeal injury, are the focus of much recent media and scholarly attention given their frequency, potential for adverse long-term health outcomes, and escalating healthcare costs [1]. If not managed appropriately, they can also lead to long-term complications which could negatively affect ability to continue to participate in exercise and sports as well as threaten general health. Management of ACL injuries is an area of controversy because it can affect long-term growth and recovery as well as the ability to participate in sports. No well-designed epidemiologic studies to document ACL injury rates have been conducted in children younger than 14 years. Although there have been reports of sports-related ACL injuries in children as young as 5 years, the limited data available suggest that ACL disruptions in children younger than 12 years are rare [2]. In 1988, McCarroll et al. [3] found that of the 1,722 ACL injuries diagnosed over a 6-year period at their sports medicine center, 3 % were in children 14 years and younger; the authors conclude that a conservative approach, although reasonable, has not always been feasible in the young population who has a strong desire to pursue competitive athletics. The Norwegian ACL surgical registry collects data for all ACL surgeries performed at participating institutions nationwide. From 2004 to 2011, this registry recorded a total of only 8–9 ACL surgeries each year for children 11–13 years of age. This represents a small fraction (0.6 %) of the total number of ACL surgeries recorded each year (1,441) in this registry across all age groups. For the children who had surgery, the age at the time of injury ranged from 9 to 13 years. The ACL surgery rate for 12- to 13-year-olds (3.5 per 100,000 citizens) was substantially lower than that for 16- to 39-year-olds (85 surgeries per 100,000 citizens), the age group at highest risk [4]. Again, these numbers underestimate the actual injury rates, because they do not account for those treated nonoperatively. ACL injury risk begins to increase significantly at 12–13 years of age in girls and at 14–15 years of age in boys. Female athletes between 15 and 20 years of age account for the largest numbers of ACL injuries reported. The gender disparity in ACL injury rates among athletes begins to appear around the time of the growth spurt (12–14 years of age for girls and 14–16 years of age for boys), peaks during adolescence, and declines in early adulthood [5]. At the high school level, ACL injury rates in gender-comparable sports (soccer, basketball, baseball/softball, track, volleyball) are 2.5–6.2 times higher in girls compared with boys [6]. In college athletics, ACL injury rates are 2.4–4.1 times higher for women, and at the professional level, ACL injury rates for men and women are essentially equal [7]. The young athlete may be particularly vulnerable to sports injury because of the physical and physiological processes of growth; moreover, young athletes might also be at increased risk of injury because of immature or underdeveloped coordination, skills, and perception. Although ACL injuries account for approximately 3 % of all injuries in college sports, they account for 88 % of injuries associated with 10 or more days of time lost from sports participation. An ACL injury at an early age is a life-changing event. In addition to surgery and many months of rehabilitation, the treatment costs can be substantial ($17,000–$25,000 per injury), and the time lost from school and sports participation can have considerable effects on the athlete’s mental health and academic performance [8]. Beyond these more immediate effects, an ACL injury also has long-term health consequences. Regardless of the type of treatment, athletes with ACL injury are up to ten times more likely to develop early-onset degenerative knee osteoarthritis, a condition that not only limits one’s ability to participate in sports but also often leads to chronic pain and disability. A systematic review of a series of long-term studies suggests that the rates of degenerative knee osteoarthritis 10–20 years after ACL injury are more than 50 % [9]. This means children and teenagers who suffer ACL injuries are likely to face chronic pain and functional limitations from knee osteoarthritis in their 20s and 30s.