Prevention of acute knee injuries in adolescent female football players: cluster randomized controlled trial.
Waldén M, Atroshi I, Magnusson H, Wagner P, Hägglund M. BMJ. 2012 May 3;344:e3042. doi: 10.1136/bmj.e3042.
http://www.ncbi.nlm.nih.gov/pubmed/22556050 (full text available for free)
Soccer is a popular sport throughout the world; however, female soccer athletes are much more prone to anterior cruciate ligament (ACL) injury than their male counterparts. One theory why female athletes are more prone to ACL injuries involves the different firing patterns of the muscles in the lower extremity in women compared to men, which leads to increased valgus load at the knee in females. Considering this hypothesis, is there a short, effective, and applicable intervention that could be implemented on a large scale to help prevent ACL injuries? The aim of this randomized clinical trial was to evaluate the effectiveness of a neuromuscular warm-up program to reduce acute knee injuries, and more specifically ACL injuries, among adolescent female soccer players. In this study, 4564 female soccer players between the ages of 12 and 17 years (in 309 soccer clubs) were randomly divided based on their teams into two parallel study groups: control group (2085 athletes in 155 clubs) and intervention (2479 athletes in 154 clubs). A neuromuscular warm-up program was designed focusing on knee control and core stability and was comprised of 6 exercises, further subdivided into four steps with progressive difficulty. The program took about 15 minutes to complete and was implemented in the intervention group and maintained through the entire duration of the soccer season. The study staff taught the program to the coach and one player on each team. Compliance was monitored by coaches during each training session in addition to random spot checks by physiotherapists throughout the study duration. Coaches also notified the physiotherapists of any knee injuries and the clinician then conducted an evaluation. Severe knee injuries were defined as an absence from play for more than four weeks. The authors noted that the intervention group had less ACL injuries (7 injuries, 0.28%) than the control group (14 injuries, 0.67%); a 64% reduction. However, there were no differences between the groups in regards to the additional end points of severe knee injuries or any acute knee injury. The authors provided some evidence that severe knee injuries or any acute knee injuries may have been lower among those considered compliant with the intervention program compared to the control group.
The findings of the study suggest that a structured 15-minute neuromuscular warm-up program can help reduce the number of ACL injuries in adolescent female soccer players. One advantage of such warm-up program is that it is monitored and implemented by the coaching staff and only requires minimal outside intervention. Therefore, it can serve as a preventive tool for ACL injuries in female adolescent players. The impact on ACL injury prevention by a neuromuscular warm-up program was also echoed in a previous study by Mandelbaum et al. It demonstrated that a neuromuscular and proprioception training program may help reduce the occurrence of ACL injuries over the long-term. In summary, more research is needed to establish the validity and clinical benefit of neuromuscular warm-up programs to prevent ACL injuries specifically and all knee injuries in general. The biggest limitation of this study is that it was neither designed nor powered to look at the rate of injury reduction during contact vs. non-contact ACL injuries with and without a neuromuscular warm up. Do you incorporate a neuromuscular training program with your adolescent females? Do you think these findings may be applied to other female sports as well as male sports?
Written by: Christian Glaser, DO and Marc I. Harwood, MD reviewed
Reviewed by: Jeffrey Driban