MARS Project



Anterior cruciate ligament (ACL) injuries, which typically occur in a young, active population are a significant risk to their lifestyle.  Surgical reconstruction to the ACL typically stabilizes the knee and allows a frequent return to previous sporting activities.  However, in 1-8% of these cases, the patient re-tears the ACL graft and a ‘revision’ ACL reconstruction is required.  Failure of a primary ACL reconstruction, while not a common event, occurs often enough to make this a significant health concern.  Unfortunately, it is commonly reported that the results of revision ACL surgery remain inferior to primary ACL reconstructions.  With these worse outcomes develops a high probability of a lifetime decrease in physical activity and physical functioning following their injury.  In addition, the patient is placed at a substantially increased risk of OA.  With the risk of early OA and decreased physical functioning comes a secondary effect of increased risk of cardiac disease, diabetes, obesity and osteoporosis. 

The overall goal of this multicenter longitudinal project is to identify clinically useful (i.e., modifiable) predictors of outcome that may inform practice decisions and improve revision ACL reconstruction outcomes. 

What does the MARS Group do?

Patients undergoing a revision ACL reconstruction by one of the participating MARS surgeons are eligible to be in this research study.  If patients are interested, they sign a research consent form.  They are then asked to fill out a 13 page questionnaire prior to their ACL surgery.  At 2, 6, and 10 years after their surgery, we will contact them and ask if they are willing to complete the same questionnaire again.  Answers to these questions will allow us to track how well they’re functioning, if they’ve undergone any additional knee surgeries, and what they’re able to do or not do as a result of their knee.


There are currently 1,200 subjects enrolled in this research study.

MARS Consortium Sites:

  • Alpine Clinic (Holderness, NH)
  • Arthroscopic and Orthopaedic Sports Medicine Associates (San Diego, CA)
  • Booth, Bartolozzi, Balderston Orthopaedics (Philadelpha, PA)
  • Bridger Orthopaedics (Bozeman, MT)
  • Case Western Reserve University (Cleveland, OH)
  • Chesapeake Orthopaedics and Sports Medicine Center (Glen Burnie, MD)
  • Children's Hospital of Philadelphia (Philadelphia, PA)
  • Cleveland Clinic Foundation (Cleveland, OH)
  • Connecticut Children’s Medical Center (Farmington, CT)
  • Commonwealth Orthopaedics and Rehab (Arlington, VA)
  • Fowler Kennedy Sports Medicine Clinic / University of Western Ontario (London, Ontario, Canada)
  • Harvard-Beth Israel Deaconess Medical Center (Boston, MA)
  • HealthPartners Regions Specialty Clinic (St. Paul, MN)
  • Hospital for Special Surgery (New York, NY)
  • Hughston Clinic (Columbus, GA)
  • Inland Orthopaedics / Washington State University (Pullman, WA)
  • Intermountain Orthopaedics (Boise, ID)
  • Keller Army Community Hospital – United States Military Academy (West Point, NY)
  • Knoxville Orthopaedic Clinic (Knoxville, TN)
  • Lenox Hill Hospital (New York, NY)
  • Mayo Clinic (Rochester, MN)
  • Methodist Sports Medicine Center (Indianapolis, IN)
  • National Sports Medicine Institute (Lansdowne, VA)
  • New York University School of Medicine (New York, NY)
  • Ohio State University (Columbus, OH)
  • OrthoCal Healthcare (San Diego, CA)
  • Orthopaedic and Fracture Clinic (Portland, OR)
  • Orthopaedic Associates of Aspen and Glenwood (Aspen, CO)
  • Orthopaedic Institute (Sioux Falls, SD)
  • Perry Orthopaedics and Sports Medicine (Charlotte, NC)
  • Princeton Orthopaedic Associates (Princeton, NJ)
  • Rush University Medical Center (Chicago, IL)
  • Slocum Research and Education Foundation (Eugene, OR)
  • The Rothman Institute / Thomas Jefferson University (Philadelphia, PA)
  • Town Center Orthopaedic Associates (Reston, VA)
  • UHZ Sports Medicine Institute (Coral Gables, FL)
  • University of British Columbia (New Westminster, BC, Canada)
  • University of Buffalo (Buffalo, NY)
  • University of California, Los Angeles (UCLA) (Los Angeles, CA)
  • University of California, San Francisco (UCSF) (San Francisco, CA)
  • University of Colorado (Boulder, CO)
  • University of Connecticut Health Center (Farmington, CT)
  • University of Iowa (Iowa City, IA)
  • University of Michigan (Ann Arbor, MI)
  • University of Missouri – Columbia (Columbia, MO)
  • University of North Carolina (Chapel Hill, NC)
  • University Orthopaedic Associates, LLC (New Brunswick, NJ)
  • University of Pittsburgh (Pittsburgh, PA)
  • University of Vermont College of Medicine (Burlington, VT)
  • Vanderbilt University (Nashville, TN)
  • Washington University (St. Louis, MO)
  • W.B. Carrell Memorial Clinic / Baylor University (Dallas, TX)

Why is this Study Important?

This research is motivated by the fact that ACL reconstruction, which allows predictable short-term return to activities, has historically reported worse outcomes in the revision setting.  This large multicenter, multisurgeon prospective study focuses on the predictors for ACL revision outcome.  Once the predictors for these inferior outcomes are identified, surgeons can be educated in modifying these variables in order to improve patients’ results.

This study presents the rare combination of both academic (54%) and private practice (46%) sites participating in this research endeavor, which will ultimately make the results generalizable.  With currently 87 IRB approved surgeons participating at 52 sites, it already represents one of the largest multisurgeon studies performed in orthopaedics.