Sports Medicine Update:
Knee Injuries in Children and Adolescents
Kevin Shea, M.D.Ron Pfeiffer, Ed.D., ATC
Over the past two decades, the number of children competing in organized sports has grown significantly. Since the passage of Title IX legislation, the number of female athletes participating in sports has increased at all levels, including youth, high school, and collegiate programs. Along with the increase in participation, the number of injuries related to sports has also increased. These injuries include both overuse and traumatic injuries.
Over the last decade, the number and severity of serious knee injuries in athletes has increased significantly. Reports of serious knee injuries in young athletes were very rare 10-15 years ago, but are now reported frequently in the literature. Although the research is limited as to the etiology of these injuries, it is probably related to several factors, including the following: 1) children are competing in year round sports, and focusing upon one sport at a young age, 2) children are being taught to play sports more aggressively, 3) and children may be reaching skeletal maturity at an earlier age.
Serious knee injuries in pediatric/adolescent athletes include ACL tears, chondral fractures, and meniscal tears. ACL injury is very common in adult female athletes, and female athletes have three to six times the risk of ACL injury compared to males when competing in comparable sports. A recent study conducted at Boise State University concluded that ACL injuries are becoming more common in female pediatric and adolescent soccer players(1). This study demonstrated that ACL injury in female soccer players were reported in athletes as young as age 12, whereas these injuries begin to appear in males at age 15 and older. Pediatric and adolescent females also have a significantly higher risk of ACL injury compared with age-matched males.
Evaluation of knee injuries is usually based upon the physical examination. Occasionally, an MRI may be necessary. MRI interpretation can be challenging in the pediatric athlete, because the normal development in skeletally immature patients can be interpreted as abnormal. The pediatric meniscus has more variability in MRI signal intensity, which is frequently misinterpreted as a meniscal tear by radiologists. The MRI can also show changes in the subchondral bone of the pediatric knee, which may be interpreted as osteochondritis dissecans or other pathological conditions. As such, it is critical that the attending physician and radiologist communicate and consider these variables when making their diagnosis. MRI findings must correlate with the physical examination, and decisions for treatment can not be made on the MRI interpretation alone. Treatment of ACL injury in skeletally immature patients is still controversial, because of concerns about the potential for damage to the growth plate during ACL reconstruction. Growth plate injury can lead to angular deformity about the knee, or discrepancy in the length of the lower extremity. Recent natural history studies of untreated ACL tears in pediatric and adolescent athletes have shown a high rate of subsequent serious knee injury, especially for athletes that return to sports. Because of the poor outcomes associated with untreated ACL tears in young athletes, many clinical researchers now recommend early ACL reconstruction in these patients. The ACL reconstruction used for these patients should be modified to minimize the risk of physeal injury, and the standard ACL reconstruction technique used for adults may not be appropriate for young patients. Several studies have shown that ACL reconstruction can be performed safely in young patients if the appropriate techniques are used. Several recent studies suggest that non-contact ACL injuries may be reduced by training programs that focus upon improved muscle strength of the lower extremities, and altered jumping kinematics(2). These interventions may be especially helpful in female athletes, because they have a much higher incidence of ACL injury. These studies are preliminary though, and additional research will be necessary to confirm the effectiveness for ACL injury prevention.
1. Shea, K. G.; Wang, J.; and Pfeiffer, R.: Age related risk factors for ACL injury in pediatric and adolescent soccer players - differences between male and females. In American Academy of Orthopaedic Surgeons Annual Meeting. San Francisco, 2001.
2. Hewett, T. E.; Lindenfeld, T. N.; Riccobene, J. V.; and Noyes, F. R.: The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study. Am J Sports Med, 27(6): 699-706, 1999.