Objective: Incidence rate (IR) of an ipsilateral or contralateral injury after anterior cruciate ligament reconstruction (ACLR) is unknown. The hypotheses were that the IR of anterior cruciate ligament (ACL) injury after ACLR would be greater than the IR in an uninjured cohort of athletes and would be greater in female athletes after ACLR than male athletes.
Design: Prospective case–control study.
Setting: Regional sports community.
Participants: Sixty-three subjects who had ACLR and were ready to return to sport (RTS) and 39 control subjects.
Independent Variables: Second ACL injury and sex.
Main Outcome Measures: Second ACL injury and athletic exposure (AE) was tracked for 12 months after RTS. Sixteen subjects after ACLR and 1 control subject suffered a second ACL injury. Between- and within-group comparisons of second ACL injury rates (per 1000 AEs) were conducted.
Results: The IR of ACL injury after ACLR (1.82/1000 AE) was 15 times greater [risk ratio (RR) = 15.24; P = 0.0002) than that of control subjects (0.12/1000AE). Female ACLR athletes demonstrated 16 times greater rate of injury (RR = 16.02; P = 0.0002) than female control subjects. Female athletes were 4 (RR = 3.65; P = 0.05) times more likely to suffer a second ACL injury and 6 times (RR = 6.21; P = 0.04) more likely to suffer a contralateral injury than male athletes.
Conclusions: An increased rate of second ACL injury after ACLR exists in athletes when compared with a healthy population. Female athletes suffer contralateral ACL injuries at a higher rate than male athletes and seem to suffer contralateral ACL injuries more frequently than graft re-tears. The identification of a high-risk group within a population of ACLR athletes is a critical step to improve outcome after ACLR and RTS.
*Sports Health and Performance Institute, The Ohio State University Medical Center, Columbus, Ohio
†Sports Medicine Biodynamics Center and Human Performance Laboratory, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
‡Division of Occupational Therapy and Physical Therapy, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
§Department of Pediatrics, College of Medicine, University of Cincinnati, Cincinnati, Ohio
¶Graduate Program in Orthopaedic & Sports Science, Rocky Mountain University of Health Professions, Provo, Utah
‖Doctor of Physical Therapy Program, San Diego State University, San Diego, California
**Division of Physical Therapy, School of Allied Medical Profession, The Ohio State University, Columbus, Ohio
††Department of Orthopedic Surgery, College of Medicine and the Departments of Biomedical Engineering and Rehabilitation Sciences, University of Cincinnati, Cincinnati, Ohio
‡‡Department of Orthopaedic Surgery, Family Medicine, Physiology and Cell Biology, College of Medicine
§§Department of Biomedical Engineering, The Ohio State University Medical Center, Columbus, Ohio
Corresponding Author: Mark V. Paterno, PT, PhD, SCS, ATC, Sports Medicine Biodynamics Center and Human Performance Laboratory, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, MLC 10001, Cincinnati, OH 45229 (firstname.lastname@example.org).
Supported by the National Institutes of Health grants (R01-AR049735, R01-AR056259, R01-AR055563, R03-AR057551, F32-AR055844) and the National Football League Charities.
The authors report no conflicts of interest.
Received July 13, 2011
Accepted December 15, 2011