A Consensus-Based Classification of Minor Complications, Major Complications, and Failure After ACL Reconstruction: A Modified Delphi Study.

Abstract

To establish a consensus-based classification of postoperative events following anterior cruciate ligament (ACL) reconstruction, clearly distinguishing no complication/normal clinical course, minor complication, major complication, and failure, using a structured Delphi methodology among international experts in ACL surgery. A three-round modified Delphi process was conducted involving international high-volume ACL surgeons. An initial set of statements addressing potential postoperative events after ACL reconstruction was developed by a working group based on clinical expertise and contemporary literature. Panelists classified each statement as no complication/normal clinical course, minor complication, major complication, or failure. Consensus was predefined as ≥75% agreement within a single category. Statements reaching consensus were retained, whereas non-consensus statements were revised and re-evaluated in subsequent rounds. Thirty-nine experts completed the first and second Delphi rounds, and 30 (76.9%) completed the third round. The initial 52 statements were expanded to 67 in round two and refined to 46 in round three. Consensus was achieved for 14 statements (26.9%) in round one, 21 statements (31.3%) in round two, and 20 statements (43.5%) in round three. Overall, consensus was reached for 55 statements, forming the final classification framework. The panel clearly distinguished graft failure-defined as graft insufficiency or symptomatic instability-from major complications requiring surgical intervention or associated with substantial morbidity, and from minor complications or expected postoperative findings. Notably, traumatic graft rupture following a clearly documented new injury was not considered a postoperative complication. This international Delphi consensus establishes a standardized and clinically meaningful classification of postoperative events following ACL reconstruction. By clearly distinguishing no complication, minor complication, major complication, and failure, this framework provides a shared language that may improve consistency in outcome reporting, facilitate comparison across studies, and enhance the interpretability of clinical research and registry data. Level V, expert consensus.