Physiologic Preoperative Knee Hyperextension Is a Predictor of Failure in an Anterior Cruciate Ligament Revision Cohort: A Report From the MARS Group
Authors:   The MARS Group, Cooper Daniel E. , Dunn Warren R. , Huston Laura J. , Haas Amanda K. , Spindler Kurt P. , Allen Christina R. , Anderson Allen F. , DeBerardino Thomas M. , Lantz Brett (Brick) A. , Mann Barton , Stuart Michael J. , Albright John P. , Amendola Annunziato (Ned) , Andrish Jack T. , Annunziata Christopher C. , Arciero Robert A. , Bach Bernard R. , Baker Champ L. , Bartolozzi Arthur R. , Baumgarten Keith M. , Bechler Jeffery R. , Berg Jeffrey H. , Bernas Geoffrey A. , Brockmeier Stephen F. , Brophy Robert H. , Bush-Joseph Charles A. , Butler V J. Brad , Campbell John D. , Carey James L. , Carpenter James E. , Cole Brian J. , Cooper Jonathan M. , Cox Charles L. , Creighton R. Alexander , Dahm Diane L. , David Tal S. , Flanigan David C. , Frederick Robert W. , Ganley Theodore J. , Garofoli Elizabeth A. , Gatt Charles J. , Gecha Steven R. , Giffin James Robert , Hame Sharon L. , Hannafin Jo A. , Harner Christopher D. , Harris Norman Lindsay , Hechtman Keith S. , Hershman Elliott B. , Hoellrich Rudolf G. , Hosea Timothy M. , Johnson David C. , Johnson Timothy S. , Jones Morgan H. , Kaeding Christopher C. , Kamath Ganesh V. , Klootwyk Thomas E. , Levy Bruce A. , Ma C. Benjamin , Maiers G. Peter , Marx Robert G. , Matava Matthew J. , Mathien Gregory M. , McAllister David R. , McCarty Eric C. , McCormack Robert G. , Miller Bruce S. , Nissen Carl W. , O’Neill Daniel F. , Owens Brett D. , Parker Richard D. , Purnell Mark L. , Ramappa Arun J. , Rauh Michael A. , Rettig Arthur C. , Sekiya Jon K. , Shea Kevin G. , Sherman Orrin H. , Slauterbeck James R. , Smith Matthew V. , Spang Jeffrey T. , Svoboda Steven J. , Taft Timothy N. , Tenuta Joachim J. , Tingstad Edwin M. , Vidal Armando F. , Viskontas Darius G. , White Richard A. , Williams James S. , Wolcott Michelle L. , Wolf Brian R. , York James J. , Wright Rick W. 
Published: June 2018

Background: The occurrence of physiologic knee hyperextension (HE) in the revision anterior cruciate ligament reconstruction (ACLR) population and its effect on outcomes have yet to be reported. Hypothesis/Purpose: The prevalence of knee HE in revision ACLR and its effect on 2-year outcome were studied with the hypothesis that preoperative physiologic knee HE ≥5° is a risk factor for anterior cruciate ligament (ACL) graft rupture. Study Design: Cohort study; Level of evidence, 2. Methods: Patients undergoing revision ACLR were identified and prospectively enrolled between 2006 and 2011. Study inclusion criteria were patients undergoing single-bundle graft reconstructions. Patients were followed up at 2 years and asked to complete an identical set of outcome instruments (International Knee Documentation Committee, Knee injury and Osteoarthritis Outcome Score, WOMAC, and Marx Activity Rating Scale) as well as provide information regarding revision ACL graft failure. A regression model with graft failure as the dependent variable included age, sex, graft type at the time of the revision ACL surgery, and physiologic preoperative passive HE ≥5° (yes/no) to assess these as potential risk factors for clinical outcomes 2 years after revision ACLR. Results: Analyses included 1145 patients, for whom 2-year follow-up was attained for 91%. The median age was 26 years, with age being a continuous variable. Those below the median were grouped as “younger” and those above as “older” (age: interquartile range = 20, 35 years), and 42% of patients were female. There were 50% autografts, 48% allografts, and 2% that had a combination of autograft plus allograft. Passive knee HE ≥5° was present in 374 (33%) patients in the revision cohort, with 52% being female. Graft rupture at 2-year follow-up occurred in 34 cases in the entire cohort, of which 12 were in the HE ≥5° group (3.2% failure rate) and 22 in the non-HE group (2.9% failure rate). The median age of patients who failed was 19 years, as opposed to 26 years for those with intact grafts. Three variables in the regression model were significant predictors of graft failure: younger age (odds ratio [OR] = 3.6; 95% CI, 1.6-7.9; P = .002), use of allograft (OR = 3.3; 95% CI, 1.5-7.4; P = .003), and HE ≥5° (OR = 2.12; 95% CI, 1.1-4.7; P = .03). Conclusion: This study revealed that preoperative physiologic passive knee HE ≥5° is present in one-third of patients who undergo revision ACLR. HE ≥5° was an independent significant predictor of graft failure after revision ACLR with a >2-fold OR of subsequent graft rupture in revision ACL surgery. Registration: NCT00625885 ( ClinicalTrials.gov identifier).