Postoperative anterior spondylodiscitis after posterior pedicle screw instrumentation

Abstract

Background context Postoperative wound infection is a well-recognized complication of spinal surgery. The infection occurs usually at the posterior wound after posterior spinal surgery. To the best of our knowledge, no report exists regarding treatment of anterior spondylodiscitis after posterior pedicle screw instrumentation. Purpose Audit of our protocols for the diagnosis and management of anterior spondylodiscitis after posterior pedicle screw instrumentation. Study design/setting A retrospective study of patients with anterior spondylodiscitis after posterior pedicle screw instrumentation, who received treatment accordingly. Patient sample Eleven patients were included. Outcome measurement The outcomes were evaluated clinically by the Oswestry Disability Index (ODI) and visual analog scale (VAS). The status of the anterior fusion was assessed according to the Bridwell grading system. Eradication of infection was determined by the level of C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). Methods From 1997 to 2008, 6,120 patients with degenerative spinal diseases and osteoporotic spine fractures were treated with posterolateral-instrumented fusion, and postoperative posterior infection was found in 135 (2.2%) patients. Postoperative anterior spondylodiscitis was noted in 11 patients. The 11 patients with anterior spondylodiscitis after posterior pedicle screw instrumentation underwent combined posterior surgery and anterior debridement with fusion simultaneously or in staged operations. The clinical outcomes were evaluated by the ODI and VAS. The status of the anterior fusion was assessed according to the Bridwell grading system. Eradication of infection was determined by the level of CRP and ESR. Results Postoperative anterior infection was diagnosed between 2 and 36 months (average, 14.8 months) after posterior surgery. The average period of recurrent axial pain and the diagnosis of infection was 19.7 weeks (2–24 weeks). The mean ESR was 66.4 mm/h (range, 20–95 mm/h) and CRP was 52.7 mg/L (range, 8.4–129 mg/L). All patients received parenteral antibiotics for 4 to 6 weeks, followed by oral antibiotics for a total of 3 months according to sensitivity tests after surgery. All patients had complete eradication of infection. The mean VAS improved from 7.9 preoperatively to 2.0 postoperatively. The mean ODI score improved from 44 to 21.1. Based on the Bridwell anterior fusion grading system, nine (82%) patients achieved Grade I fusion and two (18%) patients achieved Grade II fusion. Conclusions Anterior spine infection may occur after posterior pedicle screw instrumentation. Eleven patients with anterior spondylodiscitis, which developed after posterior pedicle screw instrumentation, were successfully treated by combined posterior surgery and anterior debridement with fusion simultaneously or in staged operations. Level of evidence Level IV, case series study.