Kleck, Christopher J.

Study Design. Modified Delphi consensus process Objective. To establish a standardized, consensus-driven definition for postoperative spine infection (PSI) for research, diagnosis, and management. Summary of Background Data. Postoperative infection is a devastating and common complication following spine surgery. Rates of PSI in the literature range from 0% to over 20% depending on surgical indication and invasiveness. Despite the implications of PSI, there is no universally accepted diagnostic standard or consensus definition for infection following spine surgery, hindering research and treatment of this challenging clinical condition. Methods. A multispecialty workgroup convened by the Musculoskeletal Infection Society (MSIS) conducted a systematic literature review. Using data from the systematic review, an expert panel completed a modified Delphi process to achieve consensus. The panel included nine fellowship-trained, board-certified physicians with expertise in infectious diseases, orthopaedic and neurologic spine surgery, and musculoskeletal radiology. Iterative rounds focused on criterion selection, importance ranking, categorical grouping, and final constellation development for PSI diagnosis. Consensus was defined as a 2/3 majority, with a target of 100%. Results. The workgroup achieved 100% consensus on a new PSI definition, which incorporates six clinical domains: wound features, microbiology, imaging, inflammatory biomarkers, intraoperative findings, and histology. A single microbiological stand-alone criterion—identification of a phenotypically indistinguishable organism from two or more deep operative site specimens—was established as pathognomonic for postoperative spine infection. Additional primary and secondary supporting criteria were defined, with specific combinations required to classify cases as definite or probable PSI. Final definitions were ratified by the boards of MSIS and the European Bone & Joint Infection Society (EBJIS) Conclusion. This consensus-based definition provides a standardized framework for diagnosing postoperative spine infection, facilitating research and clinical management. The criteria balance sensitivity and specificity across diverse clinical scenarios and represent the first multispecialty, society-endorsed definition for PSI.

OBJECTIVE There are few prior reports of acute pelvic instrumentation failure in spinal deformity surgery. The objective of this study was to determine if a previously identified mechanism and rate of pelvic fixation failure were present across multiple institutions, and to determine risk factors for these types of failures. METHODS Thirteen academic medical centers performed a retrospective review of 18 months of consecutive adult spinal fusions extending 3 or more levels, which included new pelvic screws at the time of surgery. Acute pelvic fixation failure was defined as occurring within 6 months of the index surgery and requiring surgical revision. RESULTS Failure occurred in 37 (5%) of 779 cases and consisted of either slippage of the rods or displacement of the set screws from the screw tulip head (17 cases), screw shaft fracture (9 cases), screw loosening (9 cases), and/or resultant kyphotic fracture of the sacrum (6 cases). Revision strategies involved new pelvic fixation and/or multiple rod constructs. Six patients (16%) who underwent revision with fewer than 4 rods to the pelvis sustained a second acute failure, but no secondary failures occurred when at least 4 rods were used. In the univariate analysis, the magnitude of surgical correction was higher in the failure cohort (higher preoperative T1-pelvic angle [T1PA], presence of a 3-column osteotomy; p < 0.05). Uncorrected postoperative deformity increased failure risk (pelvic incidence–lumbar lordosis mismatch > 10°, higher postoperative T1PA; p < 0.05). Use of pelvic screws less than 8.5 mm in diameter also increased the likelihood of failure (p < 0.05). In the multivariate analysis, a larger preoperative global deformity as measured by T1PA was associated with failure, male patients were more likely to experience failure than female patients, and there was a strong association with implant manufacturer (p < 0.05). Anterior column support with an L5–S1 interbody fusion was protective against failure (p < 0.05). CONCLUSIONS Acute catastrophic failures involved large-magnitude surgical corrections and likely resulted from high mechanical strain on the pelvic instrumentation. Patients with large corrections may benefit from anterior structural support placed at the most caudal motion segment and multiple rods connecting to more than 2 pelvic fixation points. If failure occurs, salvage with a minimum of 4 rods and 4 pelvic fixation points can be successful.