Predictors of Patient Reported Outcomes at Two Years Following Revision ACL Reconstruction

OBJECTIVES: Revision ACL reconstruction (ACLR) has been documented to have worse outcomes compared with primary ACLRs. The MARS Cohort was formed to elucidate predictors of outcome following revision ACLR. Patient reported outcomes (PROs) are a valid measure of results following revision ACLR. Understanding positive and negative predictors of PROs will allow surgeons to modify and potentially improve outcome for these patients. METHODS: Revision ACLR patients were identified and prospectively enrolled by 83 surgeons over 52 sites. Data collected included baseline demographics, surgical technique and pathology, and a series of validated patient reported outcome instruments (IKDC, KOOS, and Marx activity rating score). Patients were followed up at 2 years, and asked to the identical set of outcome instruments. Multivariate regression models were used to determine the predictors (risk factors) of IKDC, KOOS, and Marx scores at 2 years following revision surgery. Regression analysis was used to control for a variety of demographic and surgical factors. 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 ACLR was 3.4 years. At 2 years questionnaire follow-up was obtained on 989 subjects (82%), while phone follow-up was obtained on 1112 subjects (92%). Statistically significant (p < 0.05) positive (+) predictors for the Marx activity level included baseline (T0) higher Marx, younger age, male gender, non-smoker, non-traumatic/sudden onset mechanism of injury, 2(nd) revision, and prior ACL autograft. Negative (-) Marx predictors were having a biologic enhancement. Significant predictors of the IKDC included (+) higher T0 Marx and IKDC, male, never smoked, longer time since last ACL reconstruction and (-) previous lateral meniscectomy, Grade 3 lateral femoral condyle (LFC) chondrosis and Grades 3/4 medial tibial plateau (MTP) chondrosis. Significant predictors for KOOS symptoms subscale included (+) higher T0 KOOS symptom, longer time since ACLR, interference screw tibial fixation and (-) previous medial and/or lateral meniscectomy, Grades 3/4 MTP chondrosis. KOOS Pain predictors (+) higher T0 Marx and KOOS Pain, longer time since ACLR, (-) prior ACL soft tissue graft, suture+button/endobutton fixation, and previous medial and/or lateral meniscectomy. KOOS ADL predictors included (+) higher T0 Marx and KOOS ADL, longer time since ACLR, interference screw femoral fixation and (-) previous lateral meniscectomy, Grade 3 LFC chondrosis, and Grades 3/4 trochlear groove chondrosis. KOOS Sports/Rec predictors included (+) higher T0 Marx and KOOS Sports/Rec score, never smoked, longer time since ACLR and (-) previous lateral meniscectomy and Grades 3/4 MTP chondrosis. KOOS Knee Related Quality of Life (KRQOL) predictors included (+) higher T0 Marx and KOOS KRQOL score, never smoked, longer time since ACLR and (-) previous contralateral ACLR, 2(nd) revision, previous lateral meniscectomy, and Grade 4 MFC chondrosis. CONCLUSION: A variety of factors predict PROs both positively and negatively. Surgeon education regarding the findings in this study can result in potentially improved revision ACLR results for our patients. When the results are modifiable by the surgeon then outcomes can improve. When factors are unable to be modified then we can still improve our counseling of patients for their expected outcome.