Low-Virulent Colonialization in Patients with Screw Loosening After Spondylodesis: A Single-Center Experience.

OBJECTIVE

Screw loosening is one of the most frequent complications after instrumented spine surgery, which constitutes a heavy burden for patients and the health care 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 computed tomography scans carried out at least 12 months after revision surgery. Patients were differentiated into the following 3 groups: 1) all patients with low virulent colonialization, who received antibiotic treatment (Co + ABX); 2) all patients with colonialization without postoperative antibiotic treatment (Co-ABX); and 3) reference cohort containing all patients without colonialization (noCo).

RESULTS

Seventy-nine patients (51 females; mean age, 65.12 years) were identified. Forty-two patients (51.2%) received radiologic follow-up with computed tomography scan for implant control. These patients were assigned to 3 groups (Co + ABX: n = 5 [12%]; Co-ABX: n = 8 [19%]; noCo: n = 29 [69%]). In 10 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 of 5 patients [80%] in Co + ABX and 6 of 8 [75%] patients in Co-ABX; P > 0.05). In the reference group, noCo, in 11 of 29 patients (37.9%), recurrent screw loosening was identified (P = 0.043).

CONCLUSIONS

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.