Clinical Bottom Line
“How should I apply this information?”
Previous researchers have identified risk factors for anterior cruciate ligament (ACL) injuries and patellofemoral pain syndrome (PFP) in adolescence. The incidence of these injuries is higher for females than for males. Statistically significant results from this study included an increase in knee extensor strength, while the hamstring to quadriceps ratio and hip abductor strength decreased from prepuberty to postpuberty. The authors suggest that this muscle imbalance may be associated with an increased incidence of ACL and PFP injuries. The timing of strength changes may indicate that the optimal window for prevention is before the onset of puberty. This study guides the clinician to consider the motor control variables related to muscle strength, onset of puberty instead of chronological age, and how parameters will change over several years rather than information collected at one point in time. New insights include the pathomechanics that change during puberty. Coaches and parents may need to be informed that optimally timed, therapeutic intervention may help adolescents avoid the short- and long-term disabling effects of common knee injuries.
“What should I be mindful about in applying this information?”
The authors discuss the limitation of including only female athletes who made the soccer team for 3 consecutive years. Results cannot be generalized to males or nonathletes. Although the rigor of training was not specified for the subjects, it is something to consider for future studies because variations in exercise intensity could affect strength outcomes. Because the movement patterns required of athletes are sport specific, the level of risk and mechanisms for knee injury may vary. Therefore, adolescents engaged in different types of sports should be studied before results are applied to all athletes. This study underscores the importance of prospective, longitudinal research in contrast to single-point cross-sectional designs. Further research is needed to show that therapy intervention before puberty is preventative.
Lori Woodruff, PT, MHA, DPT
Tichenor Orthopedic Clinic for Children
Long Beach, California
Stephanie Yu, PT, MSPT, PCS
County of Los Angeles, California Children's Services
El Monte, California