Article Text

Download PDFPDF

Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study
  1. Hege Grindem1,
  2. Lynn Snyder-Mackler2,
  3. Håvard Moksnes3,
  4. Lars Engebretsen3,4,
  5. May Arna Risberg1,4
  1. 1Department of Sports Medicine, Norwegian Research Center for Active Rehabilitation (NAR), Norwegian School of Sport Sciences, Oslo, Norway
  2. 2Department of Physical Therapy, College of Health Sciences, University of Delaware, Newark, Delaware, USA
  3. 3Oslo Sports Trauma Research Center, Norwegian School of Sport Sciences, Oslo, Norway
  4. 4Department of Orthopaedics, Oslo University Hospital, Oslo, Norway
  1. Correspondence to Dr Hege Grindem, Nimi/NAR, Pb. 3848 Ullevaal Stadion, 0805 Oslo, Norway; hege.grindem{at}


Background Knee reinjury after ACL reconstruction is common and increases the risk of osteoarthritis. There is sparse evidence to guide return to sport (RTS) decisions in this population.

Objectives To assess the relationship between knee reinjury after ACL reconstruction and (1) return to level I sports, (2) timing of RTS and (3) knee function prior to return.

Methods 106 patients who participated in pivoting sports participated in this prospective 2-year cohort study. Sports participation and knee reinjury were recorded monthly. Knee function was assessed with the Knee Outcome Survey—Activities of Daily Living Scale, global rating scale of function, and quadriceps strength and hop test symmetry. Pass RTS criteria were defined as scores >90 on all tests, failure as failing any.

Results Patients who returned to level I sports had a 4.32 (p=0.048) times higher reinjury rate than those who did not. The reinjury rate was significantly reduced by 51% for each month RTS was delayed until 9 months after surgery, after which no further risk reduction was observed. 38.2% of those who failed RTS criteria suffered reinjuries versus 5.6% of those who passed (HR 0.16, p=0.075). More symmetrical quadriceps strength prior to return significantly reduced the knee reinjury rate.

Conclusions Returning to level I sports after ACL reconstruction leads to a more than 4-fold increase in reinjury rates over 2 years. RTS 9 months or later after surgery and more symmetrical quadriceps strength prior to return substantially reduce the reinjury rate.

  • Anterior cruciate ligament
  • Injury
  • Sport

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.