Risk Factors for Pseudarthrosis After Surgical Site Infection of the Spine

Douglas A. Hollern; Barrett I. Woods; Neil V. Shah; Gregory D. Schroeder; Christopher K. Kepler; Mark F. Kurd; I. David Kaye; Paul W. Millhouse; Bassel G. Diebo; Carl B. Paulino; Alan S. Hilibrand; Alexander R. Vaccaro; Kris E. Radcliff

doi:10.14444/6068

ABSTRACT

Background Pseudarthrosis following spinal fusion is a complication that frequently requires revision surgery. Reported rates of pseudarthrosis after surgical site infection (SSI) range from 30% to 85%, but few studies have identified infection as an independent risk factor for its development. The purpose of this study was to determine the incidence of clinically symptomatic pseudarthrosis in patient who developed SSI following lumbar fusion and to identify factors associated with its development.

Methods This was a retrospective review of a prospectively collected database. Patients who underwent spinal surgery and developed SSI between January 2005 and March 2015 with a minimum 2-year follow-up were included. Patient-specific and procedural characteristics were recorded. Presence of pseudarthrosis was determined clinically by the treating surgeon and was confirmed radiographically. All those in the Pseudarthrosis group required a revision procedure after the eradication of infection. Univariate and multivariate analyses were conducted as appropriate.

Results A total of 416 patients were included. Of these, 21 (5.0%) developed symptomatic pseudarthrosis following SSI. In this cohort, multivariate regression showed that age, Charlson Comorbidity Index, male sex, and surgical approach were not significant predictors of pseudarthrosis formation. However, number of levels fused was found to be the leading predictor for pseudarthrosis development (odds ratio [OR], 1.356/level, P < .001), followed by body mass index (OR, 1.083/point, P < .009) in this cohort. The number of levels fused was found to be a significant predictor of hardware removal (OR, 1.190/level, P < .001). Of the 21 pseudarthrosis cases, 85.7% found staphylococcal species, of which 27.8% exhibited methicillin-resistant Staphylococcus aureus.

Conclusions The number of spinal levels fused and body mass index are independent predictors of pseudarthrosis in patients who develop SSI after spinal fusion.

Level of Evidence Level 4

Clinical Relevance This is the first known study to specifically identify risk factors for the development of symptomatic pseudarthrosis.

Footnotes

Disclosures and COI: No authors had any conflicts of interest or disclosures that have directly or indirectly influenced this study. The following authors have no disclosures: D.A.H., N.V.S., I.D.K., B.G.D. The following authors are consultants for or have received institutional or research support from the following companies: B.I.W.: Altus, NEXXT Spine, Precision Spine, and Stryker; G.D.S.: Advance Medical, AOSpine, Medtronic, Medtronic Sofamor Danek; C.K.K.: Biomet, Medtronic, and Pfizer; M.F.K.L Duratap, Innovative Surgical Designs, and Stryker; P.W.M.: Globus Medical; C.B.P.: DePuy/Johnson & Johnson/Ethicon; A.S.H.: Amedica, Benvenue, Biomet, Lifespine, Nexgen, Paradigm Spine, PSD, Spinal Ventures, and Vertiflex; A.R.V.: Advanced Spinal Intellectual Properties, Aesculap, Atlas Spine, Avaz Surgical, Bonovo Orthopaedics, Computational Biodynamics, Cytonics, Dimension Orthotics, Electrocore, Elsevier, Flagship Surgical, FlowPharma, Gamma Spine, Gerson Lehrman Group, Globus Medical, Guidepoint Global, Health Point Capital, In Vivo, Innovative Surgical Design, Insight Therapeutics, Medacorp, Medtronic, Nuvasive, Paradigm Spine, Parvizi Surgical Innovations, Prime Surgeons, Progressive Spinal Technologies, Replication Medica, Small Bone Innovations, Spine Medica, SpineWave, Spinology, Springer, Stout Medical, Stryker, Taylor Francis/Hodder & Stoughton, Thieme, Vertiflex, and Vexim; K.E.R.: 4 Web Medical, Globus Medical, Medtronic, NEXXT Spine, Nuvasive, Orthofix Inc, Orthopedic Sciences Inc, Pacira Pharmaceuticals, Simplify Medical, Stryker, and Zimmer.