Pyogenic spondylodiscitis(PS) is a potentially life-threatening infection burdened with high morbidity rates. Despite the rising incidence, the proper diagnosis and treatment of PS are still controversial. Postoperative Vertebral Osteomyelitis(PVO) is a clinical challenge, for there were few reports about the treatment results of PVO before, and further more few studies have compared PVO with native vertebral osteomyelitis(NVO). The purpose of this study was to compare and describe the microbiology, clinical characteristics, treatment and curative effect between PVO and NVO, and analyze the prognostic factors as well.
The clinical data of 52 patients with pyogenic spondylitis admitted to the Spine Surgery Department of the First Affiliated Hospital of Xinjiang Medical University from January 2010 to December 2019 were retrospectively analyzed. There were 30 patients in native vertebral osteomyelitis (NVO) group, including 18 males and 12 females, with an average age of 50.47 ± 20.45 years old (aged from 15 to 73); 22 patients in postoperative vertebral osteomyelitis (PVO) group, including 13 males and 9 females, with an average age of 51.45 ± 16.97 years old (aged from 14 to 73). In Group NVO, 23 cases (76.7%) were located in lumbar vertebrae, 5 cases (16.7%) in thoracic vertebrae and 2 cases (6.7%) in cervical vertebrae; in Group PVO, 16 cases (72.7%) in lumbar vertebrae and 6 cases (27.3%) in thoracic vertebrae. 29 patients had had neurological dysfunction before surgery was taken. There were 26 cases of grade D (16 cases in Group NVO and 10 cases in Group PVO) and 3 cases of grade C (1 case in Group NVO and 2 cases in Group PVO), following the instructions of American Spinal Injury Association (Asia) neurological function classification. All patients were given bed rest, nutritional support and antibiotic therapy; surgical treatment for patients with poor outcomes or aggravated symptoms. Patients were followed up at 1, 3, 6 and 12 months after surgery, including leukocyte count, ESR and CRP, X-ray, CT three-dimensional reconstruction and MRI were performed. The changes of visual analogue scale (VAS) and Asia neurological function classification were observed to evaluate the clinical efficacy simultaneously.
All patients were followed up for 12-24 months. Till the last follow-up, 3 patients in Group NVO recurred, the recurrence rate was 10% (3 / 30), 9 patients in Group PVO recurred, the recurrence rate was 40.1% (9 / 22), the recurrence rate of Group PVO was higher than that of Group NVO, the difference was statistically significant (P = 0.009). Both groups were treated with intravenous and oral antibiotics, and the time of antibiotic treatment in Group PVO was longer than that in Group NVO, however the difference was not statistically significant (P = 0.094, P = 0.062). Among 44 patients with spinal internal fixation, 13.6% (1 NVO, 5 PVO) had recurrent infection after internal fixation. Therefore, we took re-operation to remove the internal fixator for infection control, patients recovered after conservative treatment such as immobilization and systemic anti infection. The numerical value of leukocytes, C-reactive protein, ESR and VAS scores of the two groups were significantly lower than those before surgery, the difference was statistically significant (P < 0.001). In Group NVO, 16 cases recovered from Asia grade D to grade E, 1 case from grade C to grade D; 10 cases in Group PVO recovered from grade D to grade E and 2 cases recovered from grade C to grade D. There was no significant difference between these two groups (P > 0.05). By univariate analysis, multiple vertebral involvement and abscess formation (P = 0.003, P = 0.025) were significantly associated with PS recurrence; there was a tendency for PS recurrence among microbial infection (OR = 1.889), spinal prosthesis (OR = 7.083) and allogenic bone (OR = 2.032), yet not obvious. By multivariate analysis, we found that multiple vertebral involvement (OR= 12.656, 95% CI: 1.536-104.303, P = 0.018) was a risk factor for PS recurrence.
The treatment of PVO is more challenging than NVO, especially in the cases of spinal implant infection. Although the antibiotic treatment time of PVO is longer than that of NVO, the recurrence rate of PVO is higher. Longer antibiotic therapy and, if necessary, surgical debridement or removal of implants are important approaches to successful treatment of PVO.