gms | German Medical Science

Objectives: Culturing of the sonication fluid of removed implants has proven to be more sensitive than conventional periprosthetic tissue culture for the microbiological diagnosis of prosthetic joint infection. But its role in postoperative spinal implant infection (PSII) is not sufficiently analyzed. Therefore, the aim of this study was to investigate the diagnostic efficacy of sonicate fluid cultures and compare it with conventional methods.

Methods: A retrospective analysis of all patients who underwent a revision surgery after instrumented spinal fusion with removal of spinal implants at our institution from 02/2015 through 2/2017, was performed. Demographic data such as age and gender, clinical manifestation, comorbidities, laboratory values including serum CRP and blood leukocytes were recorded. Furthermore microbiological, pathological and sonication culture results of revisions were investigated. PSII was diagnosed according to modified definition criteria by “Centers for Disease Control (CDC)”.

Results and conclusion: A total of 118 cases were included. 35 cases (29,7%) were identified with a PSII. The sonication fluid culture and peri-implant tissue culture had a sensitivity of 94.3% and 68.6% and specifity of 98.8% and 96.4, respectively. Interestingly, the mean time to revision was significantly shorter in cases with PSII compared to cases without (23 vs. 36 months, p=0.04). Most common microorganisms isolated were Staphylococcus epidermidis and Propionibacterium acnes.

In this study, culture of samples obtained by spinal implant sonication was more sensitive and specific than conventional peri-implant tissue culture for the microbiologic diagnosis of PSII.