Abstract:

BACKGROUND: There was incidence of delayed infection after late-onset spinal posterior surgery, but reports are different, mainly showing the presence of implants. The incidence of above infection is low in patients without implants. When infection appears, whether infection is associated with fixation cannot be effectively judged by clinical symptoms before surgery. Imaging cannot give entire affirmation. Intraoperative commonly found method is to incise and to debride, and then to wash by inserting a catheter. 
OBJECTIVE: To investigate the clinical application effects of iohexol and methylthioninium chloride in patients with posterior spinal late-onset infection and sinus tract formation, and to analyze its relationship with fixation.
METHODS: A total of 30 patients with spinal posterior late-onset infection and sinus tract formation, who were treated in the Foshan Municipal Sixth People’s Hospital, were selected in this study. Onset time was 3 months after primary surgery. There were 21 cases with fixation and 9 cases without fixation. 30 patients were randomly assigned to two groups. Before the surgery, sinus tract of patients in the observation group was infused with iohexol. Contrast radiography was conducted to identify the depth of sinus tract and the base width. After guiding intraoperative anesthesia and extent of surgery and disinfection, 2 mL of methylthioninium chloride was injected into the injured site. Sinus wall was stained. Methylthioninium chloride-stained tissue was scavenged during the surgery. Drainage was performed, followed by stage I suture. In the control group, after cutting and debridement, the catheter was inserted for washing and draining. Operation time, blood loss, postoperative visual analog scale score and re-infection rate were compared between the two groups.
RESULTS AND CONCLUSION: Operation time (45.26±7.66) minutes and the amount of blood loss (50.61±11.11) mL in the observation group were significantly lower than operation time (60.46±9.22) minutes and amount of blood loss (80.48±11.47) mL in the control group (all P < 0.05). The wounds were completely healed in both groups. At 1, 3, 6 and 12 months after surgery, re-infection did not occur in both groups. Postoperative visual analog scale score was significantly reduced over time in both groups (P < 0.05). No significant difference was detected at the same time points in both groups. These results confirmed that iohexol and methylthioniniun chloride can be effectively applied to patients with spinal posterior late-onset infection and sinus tract formation, which is helpful to assess preoperative anesthesia, to shorten the operation time and to reduce intraoperative blood loss with the presence or absence of fixation.

Key words: spine, infection, iohexol, methylene blue, pain measurement