Incidence and risk of delayed surgical site infection following instrumented lumbar spine fusion

Unexpected positive culture (UPC) in adults revision spine surgery: a systematic review and meta-analysis of incidence, risk factors, and management

BACKGROUND

Without clear signs of infection, spinal implant failure is attributed to mechanical overloads and aseptic loosening. However, how low-grade infections contribute to seemingly aseptic implant failure is unclear.

PURPOSE

The systematic review examined unexpected positive cultures (UPCs) in revision spine surgery regarding prevalence, isolated pathogens, risk factors, and strategies to reduce infection among asymptomatic patients undergoing revision spine surgery.

METHODS

We followed the PRISMA guidelines and searched four main databases (PubMed, EMBASE, SCOPUS, Web of Science) comprehensively until January 2023 for articles reporting UPC after presumed aseptic adult revision spine surgery. The UPC rates were pooled, and risk factors were compared with the culture-negative control group and represented as odds ratio (OR) or mean difference (MD).

RESULTS

Fifteen studies of 1057 individuals were included in two groups: culture-positive or UPCs (n = 317) and culture-negative or control (n = 740). The overall UPC prevalence was 33.2% (317/1057, range: 0 to 53%, 95% CI = 30.2%-36.4%), and Cutibacterium acnes (43.0%, 95% CI = 37.4%-48.8%), Coagulase-negative Staphylococci (CoNS), (39.5%, 95% CI = 33.2%-46.2%), and Staphylococcus species in general (49.5%, 95%CI = 43.7%-55.4%) were reported the most common isolated microbes. 16.1% of the UPCs were polymicrobial. Risk factors associated with UPC rates were female sex (OR = 2.62, 95%CI = 1.76-3.90, P < 0.001), screw loosening (OR = 4.43, 95%CI = 1.31-15.02, P = 0.02), number of operated levels (MD = 0.77, 95%CI = 0.33-1.22, P = 0.0007), and shorter time since index surgery (MD = - 8.57 months, 95%CI = - 14.76, -2.39, P = 0.02).

CONCLUSIONS

One-third of patients undergoing spine revision surgery revealed UPC in this study. Each UPC pathogen interpretation and antibiotic use decision should be interpreted case by case.

LEVEL OF EVIDENCE

IV.

Effectiveness of Toothbrushing Technique for Biofilm Removal and Postoperative Infection Control after Spinal Fusion Surgery: A Retrospective Study

This retrospective study was designed to investigate the effectiveness of using a toothbrush, which is commonly used in our daily life, for biofilm removal and infection control in the treatment of spinal infections occurring after spinal fusion surgery. Currently, a biofilm is thought to form on the surface of the metal inserted during spine fusion surgery. We aim to determine the differences in clinical outcomes between using and not using a toothbrush to remove biofilm while performing conventional drainage, curettage, and debridement. A total of 1081 patients who underwent anterior or posterior spinal fusion surgery between November 2018 and October 2022 were screened. The study included 60 patients who developed surgical site infection and underwent incision and drainage surgery either with a toothbrush (n = 20) or without a toothbrush (n = 40). Failure of infection control that requires revision surgery occurred in 2 patients (10%) in the Toothbrush group and in 14 patients (35%) in the No-Toothbrush group (p = 0.039). Thus, the rate of additional surgery was significantly lower in the Toothbrush group. Additionally, normalization of c-reactive protein levels occurred significantly faster in the Toothbrush group (p = 0.044). Therefore, using a toothbrush to treat spinal infections following spinal fusion surgery appears to have beneficial mechanical debridement effects, resulting in improved clinical results, which were also confirmed based on the electron microscopic images.

Epidemiology of postoperative spinal wound infection in the Middle East and North Africa (MENA) region

Background

Despite the extensive literature on postoperative spinal wound infection, yet to our knowledge, there is no previous study containing combined data from several sites in the Middle East and North Africa (MENA) region. This study aimed to estimate the incidence of surgical site infection (SSI) following spine surgeries, its associated factors, and management.

Methods

In a retrospective cohort study, medical records of all patients ≥18 years of age who underwent spine surgery at 6 tertiary referral centers in the MENA region between January 2014 to December 2019 (n=5,872) were examined to collect data on the following: (1) Patient's characteristics, (2) Disease characteristics, (3) Spine surgery approach, and (4) Characteristics of Postoperative SSI. The determinants of postoperative SSI were identified using logistic regression analysis. Receiver operating characteristic (ROC) curve was applied to identify the cut-off of the length of stay in the hospital postoperatively till the infection is likely to occur. Significance was set at p<.05.

Results

The overall incidence of SSI was 4.2% (95% CI: 3.72-4.77), in the form of deep (46.4%), superficial (43.1%), dehiscence (9.3%), and organ space (1.2%) infections. After adjusting for all possible confounders, significant predictors of postoperative SSI were; diabetes (OR=2.12, p<.001), smoking (OR=1.66, p=.002), revision surgery (OR=2.20, p<.001), open surgery (OR=2.73, p<.001), perioperative blood transfusion (OR=1.45, p=.033), ASA class III(OR=2.08, p=.002), and ≥4 days length of stay "LOS" (OR= 1.71, p=.001). A cut-off of 4 days was the optimum LOS above which postoperative SSI is more likely to occur, with 0.70 sensitivity, 0.47 specificity, and 0.61 area under the curve.

Conclusions

This is the first study that highlighted the incidence of postoperative SSI in spine surgery in the MENA region. Incidence figures are comparable to figures in different areas of the world. Identifying predictors of SSI might help high‑risk patients benefit from more intensive wound management.

Late spinal infections are more common after pediatric than after adult spinal deformity surgery

PURPOSE

To compare the incidence, timing, and microbiologic factors associated with late spinal infection (onset ≥ 6 months after index operation) in pediatric versus adult spinal deformity patients who underwent instrumented posterior spinal fusion (PSF).

METHODS

We retrospectively queried our institutional database for pediatric (aged ≤ 21 years) and adult patients who underwent instrumented PSF from 2000 to 2015. Inclusion criteria were > 12-month follow-up, spinal arthrodesis spanning 4 or more levels, and idiopathic or degenerative spinal deformity. We included 1260 patients (755 pediatric, 505 adult). Incidence, timing, and microbiologic and operative parameters of late spinal infections were compared using chi-squared and Fisher exact tests. Alpha = 0.05.

RESULTS

Late spinal infection occurred in 28 (3.7%) pediatric and 2 (0.39%) adult patients (p = 0.009). Mean onset of infection was 4.2 years (range 0.7-12) in pediatric patients and 4.0 years (range 0.7-7.3) in adults (p = 0.93). Pediatric patients underwent arthrodesis spanning more levels (mean ± standard deviation, 10 ± 2.0) compared with adults (8.4 ± 3.3) (p < 0.001). Adults experienced greater intraoperative blood loss (2085 ± 1491 mL) compared with pediatric patients (796 ± 452 mL) (p < 0.001). Culture samples yielded positive growth in 11 pediatric and 2 adult cases. Propionibacterium and coagulase-negative staphylococci were the most commonly detected microorganisms in both cohorts.

CONCLUSION

Late spinal infections were significantly more common in pediatric patients than in adults after instrumented PSF for spinal deformity. Skin and indolent microorganisms were the primary identifiable causative bacteria in both cohorts.

LEVEL OF EVIDENCE

III.

Clinical differences between delayed and acute onset postoperative spinal infection

Spine surgeons often encounter cases of delayed postoperative spinal infection (PSI). Delayed-onset PSI is a common clinical problem. However, since many studies have investigated acute PSIs, reports of delayed PSI are rare. The purpose of this study was to compare the clinical features, treatment course, and prognosis of delayed PSI with acute PSI.Ninety-six patients diagnosed with postoperative spinal infection were enrolled in this study. Patients were classified into 2 groups: acute onset (AO) within 90 days (n = 73) and delayed onset (DO) after 90 days (n = 23). The baseline data, clinical manifestations, specific treatments, and treatment outcomes were compared between the 2 groups.The history of diabetes mellitus (DM) and metallic instrumentation at index surgery were more DO than the AO group. The causative organisms did not differ between the 2 groups. Redness or heat sensation around the surgical wound was more frequent in the AO group (47.9%) than in the DO group (21.7%) (P = .02). The mean C-reactive protein levels during infection diagnosis was 8.9 mg/dL in the AO and 4.0 mg/dL in the DO group (P = .02). All patients in the DO group had deep-layer infection. In the DO group, revision surgery and additional instrumentation were required, and the duration of parenteral antibiotic use and total antibiotic use was significantly longer than that in the AO group. Screw loosening, disc space collapse, and instability were higher in the DO group (65.2%) than in the AO group (41.1%) (P = .04). However, the length of hospital stay did not differ between the groups.Delayed-onset PSI requires more extensive and longer treatment than acute-onset surgical site infection. Clinicians should try to detect the surgical site infection as early as possible.

Postoperative Management Strategy of Surgical Site Infection following Lumbar Dynesys Dynamic Internal Fixation

Aim

To research the incidence of surgical site infection (SSI) following lumbar Dynesys dynamic internal fixation and its management strategy.

Methods

We retrospectively analyzed all cases of lumbar Dynesys dynamic internal fixation performed from January 2010 to December 2019, and the data from patients with SSI were collected. The observational indicators included the incidence of SSI, general information of the patients, surgical details, inflammatory indicators, pathogenic bacteria, and treatment. SSI was defined as both early infection and delayed infection, and the cases were divided into Groups A and B, respectively. The relevant indicators and treatment were compared between the two groups.

Results

A total of 1125 cases of lumbar Dynesys dynamic internal fixation were followed up. Twenty-five cases of SSI occurred, and the incidence of SSI was 2.22% (25/1125). There were 14 cases of early infection (1.24%) and 11 cases of delayed infection (0.98%). Fourteen cases of early infection occurred 12.3 ± 8.3 days postoperatively (3–30), and 11 cases of delayed infection occurred 33.3 ± 18.9 months postoperatively (3–62). The inflammatory indicators of Group A were significantly higher than those of Group B (all P < 0.05), except for procalcitonin. The main infection site in Group A was located on the skin and subcutaneous tissue and around the internal instrument, while the main infection site in Group B was around the internal instrument. The main treatment for Group A was debridement and implant replacement, and the main treatment for Group B was implant removal. Summary. The incidence of SSI following lumbar Dynesys dynamic internal fixation was 2.22%, the incidence of early SSI was 1.24%, and the incidence of delayed SSI was 0.98%. If the main infection site of early infection is in the incision, debridement should be the main treatment method; if the infection site is around the internal fixation, implant replacement is recommended on the basis of debridement. Once delayed infection is diagnosed, implant removal is suggested.

Invasive dental procedures as risk factors for postoperative spinal infection and the effect of antibiotic prophylaxis

AIM

To identify invasive dental procedures as a risk factor for postoperative spinal infection (PSI) and evaluate the effectiveness of antibiotic prophylaxis.

MATERIALS AND METHODS

We analysed 229,335 patients who underwent spinal surgery with instrumentation from 2010 to 2017, using the nationwide database. The incidence of spinal infection 2 years after surgery was determined. Invasive dental procedures as a risk factor for PSI and the effects of antibiotic prophylaxis during this period were also analysed.

RESULTS

A total of 15,346 patients (6.69%) were diagnosed with PSI. It was found that advanced age, male sex, and a high Charlson Comorbidity Index were risk factors for PSI. The risk of PSI did not increase following dental procedures (adjusted hazard ratio [HR] 0.850; 95% confidence interval [CI], 0.793-0.912) and was not affected by antibiotics (adjusted HR 1.097; 95% CI, 0.987-1.218). Patients who received dental treatment as early as 3 months after spinal surgery had the lowest risk of postoperative infection (adjusted HR 0.869; 95% CI, 0.795-0.950).

CONCLUSIONS

Invasive dental procedure does not increase the risk of PSI, and antibiotic prophylaxis before dental procedure was not effective in preventing spinal infection.

Low-Grade Infection and Implant Failure Following Spinal Instrumentation: A Prospective Comparative Study

BACKGROUND

Spinal instrumentation can be associated with complications, including implant loosening. Hitherto, implant loosening has mainly been attributed to mechanical overload.

OBJECTIVE

To examine the role of low-grade infections as the cause of implant failure in suspected aseptic implant loosening following spinal instrumentation.

METHODS

A prospective single center observational study was performed. All patients who had revision surgery following spinal instrumentation between August 2015 and February 2018 were screened. Patients with revision surgery due to screw loosening on the computed tomograhy scan constituted the study group. Patients in which the screws where not loosened but removal was performed for other reasons formed the comparison group. Intraoperative swabs were taken and sonication was performed with the explanted material. Results of microbiological cultivation were analyzed.

RESULTS

A total of 59 patients were included in the study group and 34 in the comparison group. In the study group in 42.4% of the cultures a bacterium was detected, while in the comparison group only in 17.6%. 84%, and 83.3% of these germs were detected by sonication in the study and comparison group, respectively. The rate of positive cultures was significantly higher in the study group compared to the comparison group (P = .001). The most frequent bacterium cultivated in both groups was Propionibacterium acnes, followed by Staphylococcus species.

CONCLUSION

For patients with screw loosening a high level of suspicion for a low-grade infection should be raised. Cultures should be performed from the sonication fluid of the explanted devices in all patients with symptomatic screw loosening.

Evolution of drug-eluting biomedical implants for sustained drug delivery

In the field of drug delivery, the most commonly used treatments have traditionally been systemically delivered using oral or intravenous administration. The problems associated with this type of delivery is that the drug concentration is controlled by first pass metabolism, and therefore may not always remain within the therapeutic window. Implantable drug delivery systems (IDDSs) are an excellent alternative to traditional delivery because they offer the ability to precisely control the drug release, deliver drugs locally to the target tissue, and avoid the toxic side effects often experienced with systemic administration. Since the creation of the first FDA-approved IDDS in 1990, there has been a surge in research devoted to fabricating and testing novel IDDS formulations. The versatility of these systems is evident when looking at the various biomedical applications that utilize IDDSs. This review provides an overview of the history of IDDSs, with examples of the different types of IDDS formulations, as well as looking at current and future biomedical applications for such systems. Though there are still obstacles that need to be overcome, ever-emerging new technologies are making the manufacturing of IDDSs a rewarding therapeutic endeavor with potential for further improvements.

Delayed surgical site infection after posterior cervical instrumented surgery in a patient with atopic dermatitis: a case report

Objective: Atopic dermatitis (AD) is one of the known risk factors for Staphylococcus aureus infection. The authors report the case of a patient with cervical spondylosis and AD who developed delayed surgical site infection after posterior cervical instrumented surgery.

Patient: A 39-year-old male presented to our hospital with paralysis of the left upper extremity without any cause or prior injury. He had a history of severe AD. We performed C3–C7 posterior decompression and instrumented fusion based on the diagnosis of cervical spondylotic amyotrophy. One year after surgery, his deltoid and bicep muscle strength were fully recovered. Nevertheless, his neck pain worsened 2 years after surgery following worsening of AD. One month after that, he developed severe myelopathy and was admitted to our hospital. Radiographic findings showed that all the screws had loosened and the retropharyngeal space had expanded. Magnetic resonance imaging and computed tomography showed severe abscess formation and destruction of the C7/T1 vertebrae.

Result: We diagnosed him with delayed surgical site infection. Methicillin-resistant Staphylococcus aureus was identified on abscess culture. The patient responded adequately to treatment with antibiotic therapy and two debridements and the infection subsided.

Conclusion: We should consider the possibility of delayed surgical site infection when conducting instrumented spinal surgery in patients with severe AD.

Comprehensive Approach to Reduce Surgical Site Infections in Patients Undergoing Neurosurgical Procedures

Background: Surgical site infections (SSIs) are recognized complications of surgical procedures. Methicillin-resistant Staphylococcus aureus (MRSA) colonization increases the likelihood of developing SSIs. Decolonization of MRSA has been shown to reduce post-operative SSIs, therefore, the aim of this project was to identify and decolonize MRSA carriers and to tailor perioperative antibiotic prophylaxis to protect those at high risk for SSIs better. Methods: In September 2013, a quality improvement process initiative was implemented for pre-operative screening of MRSA nasal carriage for patients undergoing elective neurosurgical procedures. Those identified as colonized received a 10-day decolonization protocol that consisted of: oral doxycycline 100 mg twice daily or oral trimethoprim-sulfamethoxazole (TMP-SMX) DS twice daily; oral rifampin 600 mg daily; daily bathing with chlorhexidine; and twice daily use of mupirocin ointment in each nostril and under the fingernails. In addition to cefazolin (weight-based dosing), vancomycin (weight-based dosing) was recommended for perioperative prophylaxis in known MRSA carriers and patients undergoing surgical procedures involving hardware implantation irrespective of colonization status. We compared the results with our previously documented neurosurgical site infection rates (2012 and 2013 were 3.0 and 2.2%, respectively) Results: From 2014 to 2015, MRSA screening was done for 1,197 patients, of whom 52 (4.3%) were found to be colonized. Surgical site infections occurred in 14 procedures (1.4%) in 2014 and eight (0.8%) procedures in 2015, respectively. Methicillin-resistant Staphylococcus aureus remained responsible for most of these infections. None of the patients who underwent decolonization developed an infection (MRSA or otherwise). Conclusions: The overall rate of neurosurgical site infections can be reduced through a bundled approach of MRSA decolonization and change in perioperative antibiotic prophylaxis to include vancomycin for procedures involving hardware implantation irrespective of MRSA carriage state.

Is dental prophylaxis required following spinal fusion?-a systematic review and call for evidence

BACKGROUND

Controversy exists regarding the need for antimicrobial prophylaxis prior to dental procedures following spinal fusion. In this review, we attempt to synthesize a comprehensive summary of the published literature to provide recommendations on the use of antimicrobial prophylaxis before dental procedures in patients with a history of spinal fusion.

METHODS

We searched PubMed, Web of Science, Cochrane Library, and EMBASE databases from inception to February 2018. Eligible studies included patients with a history of spinal fusion treated with or without antimicrobial prophylaxis in preparation for dental procedures. Two reviewers independently assessed the eligibility of potential studies and extracted data. Outcomes of interest were the indications and efficacy of antimicrobial prophylaxis to protect against infection of spinal prostheses with dental origin.

RESULTS

A total of 1,909 articles were initially screened. After inclusion and exclusion criteria were applied, one study was found specifically relating to dental prophylaxis and spine surgery. The survey, as well as objective studies and professional organization guidelines on dental prophylaxis in patients with total hip and knee replacements, were reviewed to add context to the controversy.

CONCLUSIONS

There is a significant paucity of literature regarding dental prophylaxis in spine surgery patients. Although there has been a recent movement away from recommending antimicrobial prophylaxis before dental work in patients with other forms of orthopaedic prostheses, the gap in the literature addressing spine patients represents an important question that requires more targeted and specific research.

Can Methicillin-resistant Staphylococcus aureus Silently Travel From the Gut to the Wound and Cause Postoperative Infection? Modeling the "Trojan Horse Hypothesis"

OBJECTIVE

To determine whether intestinal colonization with methicillin-resistant Staphylococcus aureus (MRSA) can be the source of surgical site infections (SSIs).

BACKGROUND

We hypothesized that gut-derived MRSA may cause SSIs via mechanisms in which circulating immune cells scavenge MRSA from the gut, home to surgical wounds, and cause infection (Trojan Horse Hypothesis).

METHODS

MRSA gut colonization was achieved by disrupting the microbiota with antibiotics, imposing a period of starvation and introducing MRSA via gavage. Next, mice were subjected to a surgical injury (30% hepatectomy) and rectus muscle injury and ischemia before skin closure. All wounds were cultured before skin closure. To control for postoperative wound contamination, reiterative experiments were performed in mice in which the closed wound was painted with live MRSA for 2 consecutive postoperative days. To rule out extracellular bacteremia as a cause of wound infection, MRSA was injected intravenously in mice subjected to rectus muscle ischemia and injury.

RESULTS

All wound cultures were negative before skin closure, ruling out intraoperative contamination. Out of 40 mice, 4 (10%) developed visible abscesses. Nine mice (22.5%) had MRSA positive cultures of the rectus muscle without visible abscesses. No SSIs were observed in mice injected intravenously with MRSA. Wounds painted with MRSA after closure did not develop infections. Circulating neutrophils from mice captured by flow cytometry demonstrated MRSA in their cytoplasm.

CONCLUSIONS

Immune cells as Trojan horses carrying gut-derived MRSA may be a plausible mechanism of SSIs in the absence of direct contamination.

Risk of Surgical Site Infection and Mortality Following Lumbar Fusion Surgery in Patients With Chronic Steroid Usage and Chronic Methicillin-Resistant Staphylococcus aureus Infection

STUDY DESIGN

A retrospective database analysis among Medicare beneficiaries OBJECTIVE.: The aim of this study was to determine the effect of chronic steroid use and chronic methicillin-resistant Staphylococcus aureus (MRSA) infection on rates of surgical site infection (SSI) and mortality in patients 65 years of age and older who were treated with lumbar spine fusion.

SUMMARY OF BACKGROUND DATA

Systemic immunosuppression and infection focus elsewhere in the body are considered risk factors for SSI. Chronic steroid use and previous MRSA infection have been associated with an increased risk of SSI in some surgical procedures, but their impact on the risk of infection and mortality after lumbar fusion surgery has not been studied in detail.

METHODS

The PearlDiver insurance-based database (2005-2012) was queried to identify 360,005 patients over 65 years of age who had undergone lumbar spine fusion. Of these patients, those who had been taking oral glucocorticoids chronically and those with a history of chronic MRSA infection were identified. The rates of SSI and mortality in these two cohorts were compared with an age- and risk-factor matched control cohort and odds ratio (OR) was calculated.

RESULTS

Chronic oral steroid use was associated with a significantly increased risk of 1-year mortality [OR = 2.06, 95% confidence interval (95% CI) 1.13-3.78, P = 0.018] and significantly increased risk of SSI at 90 days (OR = 1.74, 95% CI 1.33-1.92, P < 0.001) and 1 year (OR = 1.88, 95% CI 1.41-2.01, P < 0.001). Chronic MRSA infection was associated with a significantly increased risk of SSI at 90 days (OR = 6.99, 95% CI 5.61-9.91, P < 0.001) and 1 year (OR = 24.0, 95%CI 22.20-28.46, P < 0.001) but did not significantly impact mortality.

CONCLUSION

Patients over 65 years of age who are on chronic oral steroids or have a history of chronic MRSA infection are at a significantly increased risk of SSI following lumbar spine fusion.

LEVEL OF EVIDENCE

3.

Time to Diagnosis and Treatment of Surgical Site Infections in Foot and Ankle Surgery

BACKGROUND

The time at which patients typically present with surgical site infections (SSI) following foot and ankle surgery has not been characterized. The primary aim of this study was to quantify the time to definitive treatment of SSIs.

METHODS

We performed a retrospective review of 1933 foot and ankle procedures in 1632 patients from 2011 through 2015. Demographic and surgical data were collected. Time to presentation in cases diagnosed with postoperative wound complications or SSIs was analyzed. Wound complications were defined as any case with concerning wound appearance that subsequently resolved with antibiotic therapy alone. SSIs were defined as cases requiring operative irrigation and debridement (I&D) for successful definitive management.

RESULTS

A total of 1569 procedures met inclusion criteria, with 17 SSIs (1.1%) and 63 wound complications (4.0%). Time between surgery and definitive treatment in the SSI group was significantly greater than in the wound complication group (28.2 ± 9.1 vs 13.4 ± 4.7 days, P < .00001). Eleven (64.7%) cases in the SSI group failed a trial of antibiotics prior to I&D, and 6 (35.3%) cases did not receive antibiotics prior to I&D. Antibiotic treatment prior to I&D did not significantly decrease the yield of intraoperative wound cultures (70% vs 100%, P = .51).

CONCLUSION

In our cohort of patients, the time to diagnosis and treatment of SSIs was longer than that of wound complications. SSIs requiring operative intervention did not present until an average of 4 weeks after surgery. These data are of some benefit in trying to define and understand SSI.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

[Risk factors for surgical site infection following posterior lumbar intervertebral fusion]

OBJECTIVE

To analyze the risk factors of surgical site infection (SSI) following posterior lumbar intervertebral fusion.

METHODS

This retrospective case-control study was conducted in 2904 patients undergoing posterior lumbar intervertebral fusion from 2011 to 2016. Forty-three patients with SSI within 30 days after the operation served as the case group, and 334 randomly selected patients without infection served as the control group. Age, gender, diabetes, body mass index (BMI), albumin level, multilevel procedures, subcutaneous fat thickness, surgery duration and the percentage of lumbar multifidus muscle fat infiltration were analyzed, and univariate and multivariate logistic regression analyses were performed to identify the risk factors of SSI.

RESULTS

Multivariate logical regression analysis identified a female gender, subcutaneous fat thickness, multilevel surgery, and lumbar multifidus muscle fat infiltration as significant risk factors for SSI (P < 0.05). BMI was not correlated with fat infiltration in the lumbar multifidus muscle (P > 0.05).

CONCLUSIONS

A female gender, multilevel surgery, subcutaneous fat thickness and fat infiltration in the multifidus muscle are related to SSI following posterior lumbar intervertebral fusion. Fat infiltration in the multifidus muscle was a spine-specific risk factor for SSI independent of BMI.

Implementation of an infection prevention bundle and increased physician awareness improves surgical outcomes and reduces costs associated with spine surgery

OBJECTIVE

Previous studies have demonstrated the efficacy of infection prevention protocols in reducing infection rates. This study investigated the effects of the development and implementation of an infection prevention protocol that was augmented by increased physician awareness of spinal fusion surgical site infection (SSI) rates and resultant cost savings.

METHODS

A cohort clinical investigation over a 10-year period was performed at a single tertiary spine care academic institution. Preoperative infection control measures (chlorohexidine gluconate bathing, Staphylococcus aureus nasal screening and decolonization) followed by postoperative infection control measures (surgical dressing care) were implemented. After the implementation of these infection control measures, an awareness intervention was instituted in which all attending and resident neurosurgeons were informed of their individual, independently adjudicated spinal fusion surgery infection rates and rankings among their peers. During the course of these interventions, the overall infection rate was tracked as well as the rates for those neurosurgeons who complied with the preoperative and postoperative infection control measures (protocol group) and those who did not (control group).

RESULTS

With the implementation of postoperative surgical dressing infection control measures and physician awareness, the postoperative spine surgery infection rate decreased by 45% from 3.8% to 2.1% (risk ratio 0.55; 95% CI 0.32–0.93; p = 0.03) for those in the protocol cohort, resulting in an estimated annual cost savings of $291,000. This reduction in infection rate was not observed for neurosurgeons in the control group, although the overall infection rate among all neurosurgeons decreased by 54% from 3.3% to 1.5% (risk ratio 0.46; 95% CI 0.28–0.73; p = 0.0013).

CONCLUSIONS

A novel paradigm for spine surgery infection control combined with physician awareness methods resulted in significantly decreased SSI rates and an associated cost reduction. Thus, information sharing and physician engagement as a supplement to formal infection control measures result in improvements in surgical outcomes and costs.

Does Nasal Carriage of Staphylococcus aureus Increase the Risk of Postoperative Infections After Elective Spine Surgery: Do Most Infections Occur in Carriers?

BACKGROUND

Wound infections after adult spinal deformity surgery place a high toll on patients, providers, and the healthcare system. Staphylococcus aureus is a common cause of postoperative wound infections, and nasal colonization by this organism may be an important factor in the development of surgical site infections (SSIs). The aim is to investigate whether post-operative surgical site infections after elective spine surgery occur at a higher rate in patients with methicillin-resistant S. aureus (MRSA) nasal colonization.

METHODS

Consecutive patients undergoing adult spinal deformity surgery between 2011-2013 were enrolled. Enrolled patients were followed up for a minimum of 3 months after surgery and received similar peri-operative infection prophylaxis. Baseline characteristics, operative details, rates of wound infection, and microbiologic data for each case of post-operative infection were gathered by direct medical record review. Local vancomycin powder was used in all patients and sub-fascial drains were used in the majority (88%) of patients.

RESULTS

1200 operative spine cases were performed for deformity between 2011 and 2013. The mean ± standard deviation age and body mass index were 62.08 ± 14.76 years and 30.86 ± 7.15 kg/m², respectively. 29.41% had a history of diabetes. All SSIs occurred within 30 days of surgery, with deep wound infections accounting for 50% of all SSIs. Of the 34 (2.83%) cases of SSIs that were identified, only 1 case occurred in a patient colonized with MRSA.

CONCLUSION

Our study suggests that the preponderance of SSIs occurred in patients without nasal colonization by methicillin-resistant S. aureus. Future prospective multi-institutional studies are needed to corroborate our findings.

Risk factors for wound complications following spine surgery

Background

Wound complications, including surgical site infections (SSIs) and wound dehiscence, are among the most common complications following spine surgery often leading to readmission. The authors sought to identify preoperative characteristics predictive of wound complications after spine surgery.

Methods

The American College of Surgeons National Surgical Quality Improvement Program database for years 2012-2014 was reviewed for patients undergoing spine surgery, defined by the Current Procedural Terminology codes. Forty-four preoperative and surgical characteristics were analyzed for associations with wound complications.

Results

Of the 99,152 patients included in this study, 2.2% experienced at least one wound complication (superficial SSI: 0.9%, deep SSI: 0.8%, organ space SSI: 0.4%, and dehiscence: 0.3%). Multivariate binary logistic regression testing found 10 preoperative characteristics associated with wound complications: body mass index ≥30, smoker, female, chronic steroid use, hematocrit <38%, infected wound, inpatient status, emergency case, and operation time >3 hours. A risk score for each patient was created from the number of characteristics present. Receiver operating characteristic curves of the unweighted and weighted risk scores generated areas under the curve of 0.701 (95% CI: 0.690-0.713) and 0.715 (95% CI: 0.704-0.726), respectively. Patients with unweighted risk scores >7 were 25-fold more likely to develop a wound complication compared to patients with scores of 0. In addition, mortality rate, reoperation rate, and total length of stay each increased nearly 10-fold with increasing risk score.

Conclusion

This study introduces a novel risk score for the development of wound dehiscence and SSIs in patients undergoing spine surgery, using new risk factors identified here.

Patient-Specific Risk Adjustment Improves Comparison of Infection Rates Following Posterior Fusion for Adolescent Idiopathic Scoliosis

BACKGROUND

There is increasing interest in surgeon "performance measures." Understanding patient factors that increase the risk of adverse events is important for the comparison of such metrics among surgeons and centers. The purpose of this study was to ascertain whether patient characteristics, beyond the control of the surgeon, were associated with increased risk of postoperative infection following posterior spinal fusion for the correction of adolescent idiopathic scoliosis (AIS) and to establish a "risk-adjusted" method of reporting postoperative infection rates.

METHODS

We reviewed the data of patients from 14 participating scoliosis treatment centers who experienced an infection within 90 days following posterior spinal fusion for the treatment of AIS. Patients with a deep infection (irrigation and debridement performed) were compared with those without an infection with regard to age, sex, body mass index (BMI) percentile for age, Lenke classification of curve type, primary curve magnitude, and estimated 3-dimensional sagittal kyphosis (T5-T12). A regression model was created to identify variables that were associated with infection, and the performance of the risk model was evaluated. The actual infection rate by site was divided by the predicted infection rate for that site and multiplied by the overall rate to create a risk-adjusted rate.

RESULTS

Of 2,122 patients analyzed, 21 (1.0%) had an infection within 90 days following surgery. Obesity was the only significant risk factor (odds ratio [OR], 7.6; p ≤ 0.001), with the resultant model demonstrating good discrimination and calibration. For the 8 sites that enrolled ≥100 patients, the predicted infection rates based on the proportion of obese patients ranged from 0.8% to 1.2%. The range of the risk-adjusted infection rates varied more substantially, from 0.2% to 2.0%.

CONCLUSIONS

For the posterior approach to surgical correction of AIS, the only identified patient risk factor for postoperative infection was a BMI percentile for age of ≥95%. To assess infection rates, we suggest adjusting for the proportion of obese patients in the cohort. A risk-adjusted infection rate for posterior spinal fusion with instrumentation for AIS allows for more accurate assessment of performance and comparison among centers.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Predictors of Hospital Readmission and Surgical Site Infection in the United States, Denmark, and Japan: Is Risk Stratification a Universal Language?

STUDY DESIGN

Retrospective review of three spine surgery databases.

OBJECTIVES

The purpose of the present study is to determine whether predictors of hospital readmission and surgical site infection (SSI) after lumbar fusion will be the same in United States, Denmark, and Japan.

SUMMARY OF BACKGROUND DATA

Because clinical decision making becomes more data driven, risk stratification will be crucial to minimize complications. Spine surgeons worldwide face this issue, leading to parallel efforts to address risk stratification. This raises the question as to whether pooled data would be valuable and whether models generated in one country would be applicable to other populations.

METHODS

Predictors of SSI and 30-day readmission from three prospective databases (National Neurosurgery Quality and Outcomes Database [N2QOD] N = 2653, DaneSpine N = 1993, Japan Multicenter Spine Database [JAMSD] N = 3798) were determined and compared to identify common or divergent predictive risks.

RESULTS

Predictive variables differed in the three databases, for both readmission and SSI. Factors predictive for hospital readmission were American Society of Anesthesiologists (ASA) grade in N2QOD (P = 0.013, odds ratio [OR] 2.08), fusion levels in DaneSpine (P = 0.005, OR 1.67), and sex in JAMSD (P = 0.001, OR = 2.81). Associated differences in demographics and procedural factors included mean ASA grade (N2QOD = 2.45, JAMSD = 1.72) and fusion levels (N2QOD = 1.39, DaneSpine = 1.52, JAMSD = 1.34). For SSI, sex (P = 0.000, OR = 3.30), diabetes (P = 0.000, OR = 2.90), and length of stay (P = 0.000, OR = 1.02) were predictive in JAMSD. No predictors were identified in N2QOD or DaneSpine.

CONCLUSION

Predictors of SSI and hospital readmission differ in the United States, Denmark, and Japan, suggesting that risk stratification models may need to be population specific or adjusted. Some differences in measured parameters exist in the three databases analyzed; however, patient and procedure selection also appear to differ and may limit the ability to directly pool data from different regions. Therefore, risk stratification models developed in one country may not be directly applicable to other countries.

LEVEL OF EVIDENCE

2.

Postoperative Nonpathologic Fever After Spinal Surgery: Incidence and Risk Factor Analysis

BACKGROUND

Although there are many postoperative febrile causes, surgical-site infection has always been considered as one of the major causes, but it should be excluded; we encountered many patients who showed delayed postoperative fever that was not related to wound infection after spinal surgery. We aimed to determine the incidence of delayed postoperative fever and its characteristics after spinal surgery, and to analyze the causal factors.

METHODS

A total of 250 patients who underwent any type of spinal surgery were analyzed. We determined febrile patients as those who did not show any fever until postoperative day 3, and those who showed a fever with an ear temperature of greater than 37.8°C at 4 days after surgery. We collected patient data including age, sex, coexistence of diabetes mellitus or hypertension, smoking history, location of surgical lesion (e.g., cervical, thoracic, lumbar spine), type of surgery, surgical approach, diagnosis, surgical level, presence of revision surgery, operative time, duration of administration of prophylactic antibiotics, and the presence of transfusion during the perioperative period, with a chart review.

RESULTS

There were 33 febrile patients and 217 afebrile patients. Multivariate logistic regression showed that surgical approach (i.e., posterior approach with anterior body removal and mesh graft insertion), trauma and tumor surgery compared with degenerative disease, and long duration of surgery were statistically significant risk factors for postoperative nonpathologic fever.

CONCLUSIONS

We suggest that most spinal surgeons should be aware that postoperative fever can be common without a wound infection, despite its appearance during the late acute or subacute period.

Surgical Adhesive Drape (IO-ban) as Postoperative Surgical Site Dressing

Study Design: Retrospective chart analysis.

Objective: The objective of this study is to describe the senior author’s (MNN) experience applying a widely available surgical drape as a postoperative sterile surgical site dressing for both cranial and spinal procedures.

Summary of Background Data: Surgical site infection (SSI) is an important complication of spine surgery that can result in significant morbidity. There is wide variation in wound care management in practice, including dressing type. Given the known bactericidal properties of the surgical drape, there may be a benefit of continuing its use immediately postoperatively.

Methods: All of the senior author’s cases from September 2014 through September 2015 were reviewed. These were contrasted to the previous year prior to the institution of a sterile surgical drape as a postoperative dressing.

Results: Only one surgical case out of 157 operative interventions (35 cranial, 124 spinal) required operative debridement due to infection. From September 2013 to September 2014, prior to the institution of a sterile surgical drape as dressing, the author had five infections out of 143 operations (46 cranial, 97 spinal) requiring intervention.

Conclusion: The implementation of a sterile surgical drape as a closed postoperative surgical site dressing has led to a decrease in surgical site infections. The technique is simple and widely available, and should be considered for use to diminish surgical site infections.