Issue link: http://connmed.csms.org/i/470788
volume 79, no. 3 149 Anterior Cruciate Ligament (ACL) Reconstruction in Skeletally Immature Athletes Carl W. NisseN, MD Introduction T he growth of organized sports for young athletes has brought to light many issues associated with athletic activities in growing, skeletally immature individuals. Over eight million students — more than half of all high school students — participate in organized high school sports. e benefits of physical activity for children, especially adolescents, are well-documented. While these benefits are overwhelmingly positive and have improved the health and well-being of these young individuals, this participation can result in injury. Treating lower extremity injuries alone in this group of high school student-athletes costs the Us over $1 billion annually. e long-term consequences on injuries in these athletes can be even more devastating from a health and social point of view. as the recognition of these injuries increases the true cost, both to the individual and society, has become more apparent. Understanding these injuries — how to prevent them better while diagnosing and treating them to avoid the long-term issues above — is a growing interest and concern for those involved in high school athletics. Incidence reports from across the nation of the increased in- cidence of anterior cruciate ligament (aCl) injuries in the skeletally immature have appeared over the past 10 years. e sports Medicine specialists at the Children's Hospital of Philadelphia (CHOP) have highlighted what appears to be a true increase in the incidence of these injuries. e authors at CHOP have compared aCl injuries to other better recognized and more easily diagnosed injuries, such as tibial spine fractures. ese fractures are traumatic in nature and due to their acute painful onset, are presumably recognized and diagnosed in most cases. Over a period of 10 years at CHOP, the incidence of tibial spine injuries did not change. Con- versely over that same 10-year period there was a 25% increase in aCl injuries. While some might argue that the increased incidence of aCl injuries is because we understand them better and are looking for them in this young group of athletes, this article and others out of CHOP seem to speak to the contrary. 1-5 Risk of Physeal Injury e concern about growth disturbances is certainly real and understandable. While the incidence may be low and can occur with or without surgery, it does occur and often leads to an unfortunate outcome. in a review of pediatric aCl reconstructions done by a highly respected group of orthopedic surgeons, a case series of 15 growth disturbances was reported on in 2002. exactly how many individuals overall that this group of 15 occurred in is not known, but the existence of growth disturbances is indisputable. 6 e growth disturbances that are caused have two likely etiologies. e first, and most common, is the creation of a physeal bar. ese bars across the growth plate stop growth all together or tether the growth at that location across the physes. Most commonly this will cause a leg length discrepancy but also could cause an angular deformity. animal models of physeal bars have been well researched and some of the growth arrests following aCl reconstructions have been by this mecha- nism. e occurrence of the growth arrest is related to the size of the transphyseal tunnel as referenced to the cross-sectional area of the physis. in a rabbit model if the tunnel exceeds 10% of the overall physeal cross-sectional area the likelihood of the bar forming increases and is significant. 7 some studies, however, show that when the physeal tunnels are drilled centrally the chances of physeal arrest are limited. is is presumably due to the tunnel being less than 4% of the tibial physeal cross- sectional area. 8 e second, and not fully understood, mechanism for physeal arrest, is the tethering of the growth plate at the Carl W. NisseN, MD, Connecticut Children's Medicine Center, Division of elite sports Medicine, Farmington and Pro- fessor, Department of Orthopaedics, University of Connecticut, Farmington, firstname.lastname@example.org.