Current Updates in Spinal Surgical Site Infections
While research on diagnosis, prevention, and treatment of spinal surgical site infections (SSIs) is rapidly emerging, there is little evidence to guide surgeons in the management of this complication, according to a meta-analysis published online ahead of print in The Spine Journal.
The incidence of spinal SSIs ranges from approximately 1% to 14%. The rates vary by type of spinal procedure with lower rates reported for deep surgical site infection (0.7%) and higher rates for repair of degenerative spondylolisthesis (4%). Rates appear to be lower with minimally invasive spinal surgeries versus open surgeries, but this benefit is not always demonstrated in studies. Patients are more likely to perceive SSIs as a serious complication, affecting their perception of surgery success, compared with surgeons.
Diagnosis and Risk Factors
Universally accepted clinical diagnostic criteria for SSI are lacking. Thus, diagnosis is typically made based upon clinical factors and laboratory values. For example, C-reactive protein level is a commonly used diagnostic factor and is elevated in more than 98% of SSI cases. Increased wound drainage occurs at approximately 10 to 14 days postoperatively and is the most common early indicator of infection, with a prevalence of 67% in patients with SSI. Pain, fever, or wound erythema occurs in less than 30% of cases.
Significant medical risk factors for spinal SSIs are shown in the Table (below). Other risk factors include the type of diagnosis, with patients undergoing surgery for trauma having a higher risk for infection than those undergoing elective surgery (9.4% vs 3.7%). In addition, more extensive tissue dissection, increased blood loss, and longer operating times may be linked to a higher risk of infection.
Studies suggest that surgeries performed later in the day have a higher risk for infection than the first case performed that day (odds ratio, 1.88). The risk for infection also varies by season with higher rates in summer and fall compared with spring and winter.
A multifactorial approach should be used in the management of SSIs, including preventive approaches such as preoperative risk stratification and improved sterilization during the operation, according to the authors. They found at least modest efficacy of the following approaches:
- Strict sterile conduct peri-operatively
- Minimized operating time
- Limited preoperative time in the operating room
- Application of local vancomycin powder or similar antibiotic therapy to the surgical site (in addition to standard peri-operative intravenous antibiotics)
Management of Infection
Treatment options include primary closure, vacuum-assisted wound closure, hardware retention, and intravenous antibiotics. The Postoperative Infection Treatment Score for the Spine (PITSS) is helpful in predicting which patients will benefit from 2-stage reconstruction (ie, irrigation and debridement with delayed primary closure) versus primary closure. Higher scores (21-33) are predictive of the need to the 2-step approach. In addition, involvement of plastic surgeons in difficult wound closures has shown efficacy.