Studies show that rates of infection after spinal surgery can range from zero to 15 per cent. The wide variation is linked to the type of operation, site, and approach. Whether or not metal implants are used is another important factor.
Spinal surgery can be done by neurosurgeons or orthopedic surgeons. The choice of surgeon is linked to the type of procedure. The authors of this study published the results of a previous study looking at risk factors for patients who had a spinal operation done by neurosurgeons.
In this new report, the rate of infection and risk factors are reviewed for spinal surgeries performed by orthopedic surgeons. The medical records of 2,316 patients who had spinal operations by orthopedic surgeons were reviewed.
There were 46 cases of surgical site infection. This means there was a two per cent rate of infection involving the spinal incision. The infections were classified as deep, organ space, or superficial.
Areas affected by deep infections included fascia and/or muscle. Organ space infections involved any space opened during the operation other than the incision. Superficial infections involved just the skin or subcutaneous tissue. Subcutaneous refers to the area just below the skin.
These 46 records were compared to 227 uninfected patients (control cases). Data collected included details about the operation and signs and symptoms of infection. They also reviewed the charts for possible risk factors.
Patients with diabetes or elevated blood sugar levels (more than 125 mg/dL but not yet diagnosed as diabetic) had the highest rates of infection. Obesity and incontinence of the bowel or bladder (before or after the operation) were additional risk factors for spinal infection.
Patients with vertebral fractures were at greater risk than those with herniated discs. Malnutrition was not a major risk factor. Timing of preventive antibiotics was also a risk factor for infection at the surgical site.
The authors suggest several strategies for reducing infection. First, monitor and balance patients’ blood glucose levels before and after surgery. Second, give prophylactic (preventative) antibiotics within 60 minutes of the incision. Antibiotics given more than an hour before the incision or after the procedure are considered suboptimal. Third, give a higher dose of antibiotic to obese patients.
Finally, having two or more surgical residents involved in the operation appears to be a risk factor for infection. This may be linked with the duration of the operation and/or the complexity of the procedure. More study is needed to examine this factor more closely.