Low-virulent colonialization in patients with screw-loosing after spondylodesis - a single center experience.

Abstract

Objective: Screw loosening is one of the most frequent complications after instrumented spine surgery, which constitutes a heavy burden for patients and the healthcare system. Low-virulent colonialization with biofilm formation has been identified as a possible cause for screw loosening. The aim of this study was to investigate the rate of low virulent infections in recurrent screw loosening after revision surgery.

Methods: Seventy-nine patients from January 2015 - July 2018 undergoing revision surgery due to clinically aseptic implant loosening were included in our observational study. Sonication of the loosened implant was performed. All identified patients received clinical and radiographic follow-up. Screw loosening was evaluated in CT-scans carried out at least 12 months after revision surgery. Patients were differentiated into three groups: One group included all patients with low virulent colonialization, who received antibiotic treatment (Co+ABX), the second group involved all patients with colonialization without postoperative antibiotic treatment (Co-ABX). The third group served as reference cohort containing all patients without colonialization (noCo).

Results: Seventy-nine patients (51 female, mean age 65.12 years) were identified. Forty-two patients (51.2%) received radiological follow-up with CT-scan for implant control. These patients were assigned to three groups (Co+ABX, n=5, 12%; Co-ABX n=8, 19%; noCo, n=29, 69%). In 10 out of 13 patients with positive sonication results (Co+ABX and Co-ABX) recurrent screw loosening occurred (76.9%). Antibiotic administration had no influence on screw loosening rates (4 out of 5 patients (80%,) in Co+ABX and 6 out of 8 (75%) patients in Co-ABX (p>0.05). In the reference group noCo 11 out of 29 patients (37.9%) recurrent screw loosening was identified (p=0.043).

Conclusion: In patients with screw revision surgery incidence of low-virulent microorganism colonialization is high and may play a role in the incidence of screw loosening. New therapeutic approaches addressing low-virulent infections and biofilm formation may be helpful.