Article Text


Keeping athletes on the field: preventing primary and secondary ACL injuries
  1. Amelia J.H. Arundale
  1. Biomechanics and Movement Science Program, University of Delaware, Newark, Delaware, USA
  1. Correspondence to Dr Amelia J.H. Arundale, Biomechanics and Movement Science Program, University of Delaware, Newark, DE 19711, USA; arundale{at}

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What did I do?

I aimed to (1) examine the changes in biomechanics and injury incidence with utilisation of the 11+ prevention programme over two soccer seasons in collegiate women, (2) establish the incidence of lower extremity injuries and career duration after ACL reconstruction (ACLR) and return Major League Soccer (MLS) and (3) quantify the effects of a secondary injury prevention programme on function, return to sport, and second ACL injury incidence in athletes after ACLR.

Why did I do it?

Due to the high incidence of ACL injuries in cutting, pivoting and jumping sports, it would change athletes’ lives if it were possible to prevent a first or a second ACL injury.1 Primary and secondary ACL injury prevention programmes have been developed but require outcomes testing to determine their efficacy and further improve their impact.

How did I do it?

Aim 1

Two collegiate women’s soccer teams performed the 11+ prevention programme2 for two seasons, while a control team performed their normal warm-up. Injuries were recorded and biomechanical changes were assessed via motion analysis of a drop jump during preseason and postseason.

Aim 2

I compared the career length and lower extremity injury incidence of athletes who had an ACLR and returned to play in MLS with those of age-matched control athletes.

Aim 3

I performed a secondary analysis of a randomised control trial investigating the ACL-Specialized Post-Operative Return-to-Sport (ACL-SPORTS) programme (NCT01773317).3 I compared changes in functional and patient-reported outcomes over the course of the programme between men and women and in the men explored the return to sport and second ACL injury outcomes over the first 2 years after ACLR. (I only reported on the men as not all of the women had completed the 2-year follow-up.)

Figure 1

Single-legged hopping over hurdles, part of the ACL-Specialized Post-Operative Return-to-Sport return-to-sport and secondary ACL injury prevention programme.

What did I find?

Aim 1

The 11+ led to fewer lower extremity injuries during the first season but did not change biomechanical risk factors4 associated with ACL injuries in either the first or second season. Further, in the second season of 11+ use, there was an increased knee injury risk, including three ACL injuries.

Aim 2

After ACLR and return to MLS, athletes had half as long careers compared with controls, and while playing, ACL group athletes started fewer and were unused in more regular/postseason games. Athletes after ACLR did not have a higher risk for lower extremity injuries but did seem to have a lower risk for thigh and hamstring injuries.

Aim 3

Both men and women improved in functional and patient-reported outcomes with the ACL-SPORTS programme, with one exception. Men and women started the programme with similar quadriceps strength limb symmetry, but over the course of the programme men had improvements in limb symmetry and women did not. Two years after ACLR, all of men had returned to sport, 95% at their preinjury level, and there was only one second ACL injury.

What is the most important clinical impact/practical application

Aim 1

The 11+ is effective and should be implemented to reduce lower extremity injuries in collegiate women soccer players.

Aim 2

These results support the view of return to sport as a continuum, not a single time point.5 After ACLR, MLS athletes return to participation and to play, but sports medicine teams may need to focus more on helping these athletes truly return to performance.

Aim 3

Finally, the ACL-SPORTS programme may be a beneficial secondary prevention programme for men who wish to return to sport after ACLR. The programme seems to be valuable for men and women, but during the return-to-sport phase of rehabilitation when many clinicians shift their focus to sport-related activities, women may need a continued focus on strengthening, especially given the implications of quadriceps asymmetry on reinjury risk.6


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  • Contributors Lynn Snyder-Mackler advised this dissertation, alongside the dissertation committee of Karin Gravere-Silbernagel, Daniel White, and Stefano Della Villa. Holly Silvers-Granelli, Ryan Zarzycki, Adam Marmon and Celeste Dix all helped with the FIFA11+ study in aspects of data collection, processing, analysis and manuscript editing. Ryan Zarzycki, Jacob Capin and Angela Smith all helped with the ACL-SPORTS study in aspects of data collection, processing and manuscript editing.

  • Funding National Institute of Child Health and Human Development (grant number R44 HD068054) and National Institute of Arthritis and Musculoskeletal and Skin Diseases (grant number R01 AR048212). Support was also provided by a Legacy Grant from the Sports Section of the American Physical Therapy Association and a Promotion of Doctoral Studies I Scholarship from the Foundation for Physical Therapy.

  • Competing interests None declared.

  • Ethics approval University of Delaware Internal Review Board.

  • Provenance and peer review Not commissioned; internally peer reviewed.

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