Selection pressures of vancomycin powder use in spine surgery: a meta-analysis.

BACKGROUND CONTEXT: Surgical site infection (SSI) is a serious and costly complication of spine surgery. Many surgeons apply vancomycin powder to the surgical wound to prevent SSIs. While multiple studies have reported reduced rates of SSI, others have suggested that widespread use of intrawound vancomycin may increase the incidence of vancomycin-resistant, gram-negative, or polymicrobial spinal infections. PURPOSE: To systematically review the current literature on vancomycin powder in spine surgery and its impact on SSI culture profiles. STUDY DESIGN: Meta-analysis. SAMPLE: We included observational studies, retrospective chart reviews, and randomized controlled trials of patients who underwent spine surgeries with and without vancomycin powder application to surgical wounds and reported SSI rates. OUTCOME MEASURES: The primary outcome was postoperative SSIs. Subgroup analyses compared rates of postoperative SSIs. METHODS: We performed a comprehensive search of numerous electronic databases and conference proceedings pertaining to this topic. Our meta-analysis was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Inclusion criteria consisted of spine surgeries with or without use of vancomycin powder, case-control design, sample sizes of at least 10 in each arm, SSIs identified with bacterial cultures, and follow-up of at least 1 month. Data extracted from eligible studies included, but was not limited to, SSI rates, cultured organisms, and vancomycin powder dose. Chi-square analyses were used to assess pooled risk-estimates of intrawound vancomycin powder on reducing SSIs and selecting for gram-negative and/or polymicrobial organisms compared to controls. Pooled odds ratios, relative risks, and relative risk increase for observed outcomes were calculated. A meta-analysis was then performed with a forest plot to determine risk estimates' heterogeneity with I2 index, Q-statistic, and p value under a fixed-effects model. Funnel plot was used to assess publication bias. None of the authors received funding or other support for this review. RESULTS: After reviewing nearly 400 titles and abstracts, 28 articles met inclusion criteria. They included two randomized controlled trials, one observational study, and 25 retrospective analyses. There were 412 cases of SSI (3.8%) in the control group (N=10,846) compared to 197 SSIs (2.3%) in the vancomycin powder group (N=8,456). The pooled odds ratio was 0.60 (95% confidence intervalCI 0.51-0.71, p<.05). The rate of gram-positive SSI was significantly higher in the control group compared to the vancomycin group (70% vs. 45.1%, p<.05). The rate of gram-negative and polymicrobial SSI was significantly higher in the vancomycin group (35.8% vs. 18.5%, p<.05). The risk of developing a gram-negative or polymicrobial SSI was nearly twice (93.5% higher) in the vancomycin group. Study heterogeneity and synthesizing mostly retrospective data were primary limitations. CONCLUSIONS: Widespread use of prophylactic intrawound vancomycin may increase the incidence of gram-negative and polymicrobial SSIs. Vancomycin powder should likely be restricted to procedures and patients most at risk for infection.

Does Addition of Tobramycin Powder Reduce Infection Rates After Spine Surgery?

STUDY DESIGN: Retrospective chart review. OBJECTIVES: To evaluate the efficacy of tobramycin and vancomycin powder in reducing surgical site infections in posterior lumbar instrumented fusion. METHODS: A multicenter, electronic database search was conducted for all patients who underwent posterior instrumented lumbar fusions. RESULTS: The addition of vancomycin powder decreased postoperative infections from an incidence of 5.7% down to a rate of 2.0%. This difference was statistically significant (P = .018). The addition of tobramycin powder to the wound in addition to vancomycin further decreased the infection rate down to 1.8%. The postoperative infection rate was statistically significant (P = .041) when compared with the no-powder group. However, the difference was not statistically significant (P = 1.00) when compared with vancomycin alone. There was also a trend toward gram-negative organisms with the addition of more antibiotic powder. In the control group, for example, the organisms cultured were 66% methicillin-sensitive Staphylococcus aureus and 33% gram-negative organisms. In the vancomycin group, 30% of the organisms cultured were Staphylococcus aureus and 60% gram-negative organisms. In the vancomycin and tobramycin powder group, 100% of the organisms cultured were gram-negative. CONCLUSIONS: There is a reduction in surgical site infections with addition of antibiotic powder to the wound prior to closure. However, the reduction in the infection rate was not as great with the addition of tobramycin powder to vancomycin alone and there was a noticeable change in the spectrum of organism cultured with this addition. Clinicians should consider the risk-to-benefit ratio in each case when deciding to use antibiotic powder.

Delayed gadolinium-enhanced magnetic resonance imaging of cartilage to predict early failure of Bernese periacetabular osteotomy for hip dysplasia.

BACKGROUND: Hip dysplasia leads to abnormal loading of articular cartilage, which results in osteoarthritis. Pelvic osteotomies such as the Bernese periacetabular osteotomy can improve the mechanics of the joint, but the results are variable and appear to depend on the amount of preexisting arthritis. Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) is a technique designed to measure early arthritis, and it potentially could be used to select hips with too severe arthritis to benefit from a joint-preserving reconstructive procedure. The purpose of our study was to identify radiographic, clinical, and magnetic resonance imaging measurements that predict failure after pelvic osteotomy. METHODS: We performed a cohort study of forty-seven patients undergoing a Bernese periacetabular osteotomy for the treatment of hip dysplasia. Our goal was to identify preoperative radiographic factors, such as the grade of arthritis, joint congruency, and the dGEMRIC index, that are associated with a poor outcome after osteotomy. RESULTS: Hips in which the osteotomy did not fail had a significant decrease in pain compared with their status preoperatively (p < 0.0001). Hips in which the osteotomy did fail had had significantly more arthritis on preoperative radiographs (as demonstrated by the joint space width and the Tönnis grade [p = 0.01]), more subluxation (p = 0.02), and a lower dGEMRIC index (p < 0.001) than the hips in which the osteotomy did not fail. Multivariate analysis identified the dGEMRIC index as the most important predictor of failure of the osteotomy. CONCLUSIONS: Bernese periacetabular osteotomy for the treatment of hip dysplasia can decrease pain and improve function in symptomatic dysplastic hips. The dGEMRIC index, as an early measure of osteoarthritis, appears to be useful for identifying poor candidates for a pelvic osteotomy. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions to Authors for a complete description of levels of evidence.