What does a failure in anterior cruciate ligament reconstruction really mean? An integrative view

Anterior cruciate ligament reconstruction (ACLR) is among the most frequently performed and successful procedures in orthopedic surgery. Nevertheless, a substantial proportion of patients experience postoperative "failure," a term that remains inconsistently defined throughout the literature. This narrative review critically analyzes the heterogeneity of definitions applied to ACLR failure, underscoring persistent gaps, contradictions, and their implications for clinical practice and research. We subsequently propose an integrative definition that aligns with both the clinical and functional objectives of reconstruction. Failure may result from multiple factors, including but not limited to technical, biological, traumatic, and patient-related, and inconsistencies arise when definitions rely exclusively on graft rupture, revision surgery, laxity thresholds, or isolated patient-reported symptoms. Although current consensus statements acknowledge this variability, they fail to provide operational definitions. Consequently, reported failure rates vary considerably, limiting comparability across studies. We advocate defining ACLR failure, as the presence of any of the following: objective or subjective post-operative instability, persistent knee pain, functional limitation including restricted range of motion, documented graft rupture, or new symptomatic meniscal injury in the absence of significant trauma. This multidimensional, patient-centered framework reflects the fundamental goals of ACLR and may serve as a foundation for standardized reporting criteria in future clinical and research endeavors.