Surgical Predictors of Clinical Outcome following Revision ACL Reconstruction

OBJECTIVES: Revision ACL reconstruction has been documented to have worse outcomes compared with primary ACL reconstructions. The reasons why remain unknown. The purpose of this study was to determine either previous or current surgical factors noted at the time of ACL revision reconstruction predicts activity level, sports function, and OA symptoms at two year follow-up. METHODS: Revision ACL reconstruction patients were identified and prospectively enrolled between 2006 and 2011. Data collected included baseline demographics, surgical technique and pathology, and a series of validated patient reported outcome instruments (IKDC, KOOS, WOMAC, and Marx activity rating score). Patients were followed up for 2 years, and asked to complete the identical set of outcome instruments. Regression analysis was used to control for age, gender, BMI, activity level, baseline outcome scores, revision number, time since last ACLR, and a variety of previous and current surgical variables, in order to assess the surgical risk factors for clinical outcomes 2 years after revision ACL reconstruction. RESULTS: 1205 patients met the inclusion criteria and were successfully enrolled. 697 (58%) were males, with a median cohort age of 26 years. The median time since their last ACL reconstruction was 3.4 years. Baseline characteristics of the cohort are summarized in Table 1. At 2 years, follow-up was obtained on 82% (989/1205). Both previous as well as current surgical factors were found to be significant drivers of poorer outcomes at 2 years (Table 2). The most consistent surgical factors driving outcome in revision patients were prior surgical technique, prior tibial tunnel position, current femoral fixation and having a notchplasty. Having a previous arthrotomy compared to the one incision technique resulted in significantly poorer outcomes on the IKDC (odds ratio=0.41; 95% CI=0.17-0.95; p=0.037) and KOOS pain, sports/rec, and QOL subscales (OR range=0.23-0.42; 95% CI=0.10-0.97; p<0.05). Using a metal interference screw for current femoral fixation resulted in significantly better outcomes in 2 year KOOS symptoms, pain, and QOL subscales (OR range = 0.51-0.59; 95% CI=0.30-1.00; p<0.05), as well as WOMAC stiffness (OR=0.57; 95% CI=0.33-0.98; p=0.041). Avoiding a notchplasty significantly improved 2 year outcomes of the IKDC (OR=1.47; 95% CI=1.08-1.99; p=0.013), KOOS ADL and QOL subscales (OR range = 1.40-1.41; 95% CI=1.03-1.93; p<0.04), and the WOMAC stiffness and ADL subscales (OR range = 1.41-1.49; 95% CI=1.03-2.05; p<0.04). Lower baseline outcome scores, activity level, higher BMI, female gender, and shorter time since the patient’s last ACL reconstruction all significantly increased the odds of reporting poorer clinical outcomes at 2 years. Prior femoral fixation, prior femoral aperture position, and the knee flexion angle at the time of graft fixation were not found to be significant risk factors for 2 year outcomes in this revision cohort. CONCLUSION: There are surgical variables that the physician can control at the time of an ACL revision which have the ability to modify clinical outcomes at 2 years. Whenever possible, opting for an anteromedial portal or transtibial surgical exposure, choosing a metal inference screw for femoral fixation, not performing a notchplasty, and not using a biologic enhancement will improve the patient’s odds of having a significantly better 2 year clinical outcomes.