Subsequent surgery after primary ACLR results in a significantly inferior subjective outcome at a 2-year follow-up

PURPOSE: To analyze minimal important change (MIC), patient-acceptable symptom state (PASS) and treatment failure after reoperation within 2 years of primary ACL reconstruction and compare them with patients without additional surgery. METHODS: This is a retrospective follow-up study of a cohort from a single-clinic database with all primary ACLRs enrolled between 2005 and 2015. Additional surgery within 2 years of the primary ACLR on the ipsilateral knee was identified using procedural codes and analysis of medical records. Patients who completed the Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaire preoperatively and at the 2-year follow-up were included in the study. MIC, PASS and treatment failure thresholds were applied using the aggregate KOOS (KOOS(4)) and the five KOOS subscales. RESULTS: The cohort included 6030 primary ACLR and from this 1112 (18.4%) subsequent surgeries were performed on 1018 (16.9%) primary ACLRs. 24 months follow-up for KOOS was obtained on 523 patients (54%) in the reoperation group and 2084 (44%) in the no-reoperation group. MIC; the no-reoperation group had a significantly higher improvement on all KOOS subscales, Pain 70.3 vs 60.2% (p < 0.01), Symptoms 72.1 vs 57.4% (p < 0.01), ADL 56.3 vs 51.2% (p < 0.01), Sport/Rec 67.3 vs 54.4% (p < 0.01), QoL 73.9 vs 56.3% (p < 0.01). PASS; 62% in the non-reoperation group reported their KOOS(4) scores to be satisfactory, while only 35% reported satisfactory results in the reoperated cohort (p < 0.05). Treatment failure; 2% in the non-reoperation group and 6% (p < 0.05) in the reoperation group considered their treatment to have failed. CONCLUSION: Patients who underwent subsequent surgeries within 2 years of primary ACLR reported significantly inferior outcomes in MIC, PASS and treatment failure compared to the non-reoperated counterpart at the 2-year follow-up. This study provides clinicians with important information and knowledge about the outcomes after an ACLR with subsequent additional surgery. LEVEL OF EVIDENCE: III.