Issue: Issue 6 2009
November 01, 2009
2 min read

Previous spine surgery a strong predictor of deep infection after lumbar fusion

A study found that infection risk is also increased after lengthy surgeries and in patients who smoke.

Issue: Issue 6 2009
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Patients who underwent lumbar spinal fusion surgery had nearly a three times greater risk of developing deep surgical-site infections if they had previous surgery in the same area, Dutch researchers concluded from a case-controlled analysis.

“Our main finding is that previous surgery was associated with the higher risk for the appearance of an infection. The length of surgery in minutes was also an independent risk factor. More complex surgery resulted in an increase for the infection rates,” Janneke J.P. Schimmel, MSc, said at the 36th Annual Meeting of the International Society for the Study of the Lumbar Spine in Miami.

Investigators at Sint Maartenskliniek in Nijmegen, The Netherlands, studied 1,454 patients who underwent 1,501 lumbar fusions there between January 1999 and December 2007. They identified patient, surgical and postoperative factors related to the occurrence of a deep infection.

Smoking and diabetes mellitus were other factors they associated with greater risk of deep infection after lumbar fusion.

Infection rate: 2.1%

Janneke J.P. Schimmel, MSc
Janneke J.P. Schimmel, MSc, presented data indicating that previous surgery was a risk factor for infection following lumbar fusion.

Image: Trace R, Orthopedics Today

In conducting the case-control study, the researchers mainly sought to identify factors that were modifiable. They collected data for their analysis from standardized patient charts and hospital databases using standardized forms, according to Schimmel. The investigators tried to corroborate the diagnosis infection by microbiology. Only those infections that were obviously caused by microorganisms were counted as such.

Researchers performed univariate and multivariate logistic regression to analyze the relationship between all the risk factors they identified.

Among those studied, 31 deep infections were identified, producing an infection rate of 2.1%, she said.

According to the literature, deep infection rates in these surgeries range from about 1% to 12%, Schimmel noted.

Cost factors

Based on the study’s findings, 90% of infections were due to Staphylococcus aureus and the time to postoperative diagnosis was 14 days. Furthermore, 66 additional surgeries and 1,003 extra hospital days were necessary to treat the infections, Schimmel told Orthopedics Today.

Operative factors, including procedures that lasted only a few minutes longer than usual, increased the risk of deep infection, Schimmel explained.

“An increase of 1 minute operative time increased the risk [of infection] by 1%. This means that in a 30-minute-longer surgery, the risk increased 1½ times the basic risk of infection,” she said.

Managing deep infection is costly due to the associated increased hospital stays and the use of expensive antibiotic treatment, laboratory tests abd radiologic procedures. Therefore, these high risk patients should be included in a specific clinical pathway in the future, Schimmel noted.

For more information:
  • Janneke J. P. Schimmel, MSc, can be reached at Sint Maartenskliniek, Department of Research Development and Education, P.O. Box 9011, 6500 GM, Nijmegen, The Netherlands; 31-24-3528119; e-mail: Orthopedics Today could not determine if she has any financial connections to products or companies mentioned in the article.