The Role of the AO Spine Primary Infection Classification in Evaluating Medical and Surgical Management: A Narrative Review

Study Design Narrative review. Objectives To clarify definitions and classifications regarding the diagnosis, medical managementand role of spinal surgery in the treatment of primary pyogenic spinal infections. Methods A comprehensive review of the MEDLINE, OVID, Embase, Google Scholar and Cochrane Database of Systematic reviews was conducted to characterize historical means of diagnosing spondylodiscitis and explore current controversies in the management of primary pyogenic spinal infections. This includes evaluating the role of aggressive early surgical intervention versus conservative maximal medical management. The AO Spine Primary Infection Classification System is introduced and framed against this historical backdrop. Results Surgical intervention in the treatment of pyogenic spinal infection is traditionally reserved for cases of neurological deficit, mechanical instability, or to facilitate microbiological diagnosis. Contemporary studies contend that early surgical debridement leads to superior source control and improved functional as well as neurological outcomes. We note that the majority of these studies are retrospective in nature and that there is a consistent lack of a clear definition of spondylodiscitis or stage of pyogenic primary spinal infection, variation in antibiotic regimens and lack of clear definitions as to what constitutes early or late surgery. Conclusions Patients who suffer from pyogenic primary spinal infections present at different time courses along their illness and therefore existing studies examining early or late surgical interventions are confounded by this heterogeneity. Existing studies remain disparate due to the absence of a reliable classification. The AO Spine Primary Infection Classification System presents a universal and standardized means of communicating severity of spinal infections.