Intrawound Treatment for Prevention of Surgical Site Infections in Instrumented Spinal Surgery: A Systematic Comparative Effectiveness Review and Meta-Analysis

Synthesis and evaluation of a novel vancomycin-infused, biomimetic bone graft using a rat model of spinal implant-associated infection

Background

Postoperative infection is a complication of spinal fusion surgery resulting in increased patient morbidity. Strategies including intraoperative application of powdered vancomycin have been proposed to reduce the incidence of infection; however, such antimicrobial effects are short-lived.

Methods

Instrumentation of the L4-L5 vertebrae was performed mimicking pedicle screw and rod fixation in 30 rats. Titanium instrumentation inoculated with either PBS or 1×105 CFU bioluminescent MRSA, along with biomimetic bone grafts infused with varying concentrations of vancomycin and 125 µg of rhBMP-2 (BioMim-rhBMP-2-VCM) were implanted prior to closure. Infection was quantified during the six-week postoperative period using bioluminescent imaging. Arthrodesis was evaluated using micro-CT.

Results

Infected animals receiving a bone graft infused with low-dose (0.18 mg/g) or high-dose vancomycin (0.89 mg/g) both exhibited significantly lower bioluminescent signal over the six-week postoperative period than control animals inoculated with MRSA and implanted with bone grafts lacking vancomycin (p=.019 and p=.007, respectively). Both low and high-dose vancomycin-infused grafts also resulted in a statistically significant reduction in average bioluminescence when compared to control animals (p=.027 and p=.047, respectively), independent of time. MicroCT analysis of animals from each group revealed pseudoarthrosis only in the control group, suggesting a correlation between infection and pseudoarthrosis. MRSA-inoculated control animals also had significantly less bone volume formation on micro-CT than the PBS-inoculated control cohort (p<.001), the MRSA+low-dose vancomycin-infused bone graft cohort (p<.001), and the MRSA+high-dose vancomycin-infused bone graft cohort (p<.001).

Conclusion

BioMim-rhBMP-2-VCM presents a novel tissue engineering approach to simultaneously promoting arthrodesis and antimicrobial prophylaxis in spinal fusion. Despite mixed evidence of potential osteotoxicity of vancomycin reported in literature, BioMim-rhBMP-2-VCM preserved arthrodesis and osteogenesis with increasing vancomycin loading doses due to the graft's osteoinductive composition.

Reduction of Instrumentation-Related Spine Surgical Site Infections After Optimization of Surgical Techniques. A Single Center Retrospective Analysis

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Although surgical risk factors for developing spine surgical site infections (S-SSI) have been identified, the impact of such knowledge in its prevention has not been demonstrated.

METHODS

We evaluated in 500 patients undergoing spine surgery between 2011 and 2019 at Hospital 12 de Octubre the changes in S-SSI rates over time. Surgical variables independently related to S-SSI were analyzed by univariate and multivariate analysis using binary logistic regression models. A case-control sub-analysis (1:4), matched by the surgical variables identified in the overall cohort was also performed.

RESULTS

Twenty cases of S-SSI were identified (4%), with a significant decrease in the incidence rate across consecutive time periods (6.6% [2011-2014] vs .86% [2015-2019]; P-value <.0001)). Multivariate analysis identified arthrodesis involving sacral levels (odds ratio [OR]: 2.57; 95% confidence interval [95%CI]: 1.02-6.47; P-value = .044) and instrumentation over 4-8 vertebrae (OR: 2.82; 95%CI: 1.1-7.1; P-value = .027) as independent risk factors for S-SSI. The reduction in the incidence of S-SSI concurred temporally with a reduction in instrumentations involving 4-8 vertebrae (55% vs 21.8%; P-value <.0001) and sacral vertebrae (46.9% vs 24.6%; P-value <.0001) across both periods. The case-control analysis matched by these surgical variables failed to identify other factors independently related to the occurrence of S-SSI.

CONCLUSIONS

Spinal fusion of more than 4 levels and the inclusion of sacral levels were independently related to the risk of S-SSI. Optimization of surgical techniques by reducing these two types of instrumentation could significantly reduce S-SSI rates.

Reducing surgical site infections after spine surgery: the optimal amount of normal saline for intra-wound irrigation

BACKGROUND CONTEXT

Surgical site infection (SSI) following lumbar surgery can increase healthcare costs and lead to poor clinical outcome. Irrigation of wounds with saline solution is widely accepted globally and safe for nearly all kinds of surgery. However, the efficacy of different volumes of wound irrigation has not been addressed in elective spine surgery. The role and the optimal amount of intraoperative wound saline irrigation in preventing SSI in clean spinal surgery remain unclear.

PURPOSE

We aimed to investigate if insufficient intraoperative irrigation may be a risk factor for postoperative SSI. Additionally, we investigated the optimal amount of normal saline (NS) for irrigation to prevent postoperative SSI.

STUDY DESIGN

This is a retrospective study of patients with degenerative spinal stenosis who were treated surgically. Patients were grouped according to the amount of intra-wound irrigation during surgery.

PATIENT SAMPLE

We included 444 patients with degenerative lumbar spinal conditions who had undergone one to five level open spinal fusion surgeries from January 2015 through April 2020.

OUTCOME MEASURES

The definition of superficial or deep SSI in this study was based on the Centers for Disease Control and Prevention criteria for SSI. The fusion status accessed was based on the Bridwell grading system at the final follow-up. Self-reported and clinical outcome measures include visual analog scale and Oswestry Disability Index.

METHODS

A total of 193 patients underwent irrigation with a bulb syringe with manual method (B group) with 2,000 mL NS; 251 patients underwent interpulse battery-powered device irrigation (P group) with >6,000 mL NS. Based on our protocolized departmental guidelines, all patients received the same preoperative preparation and standard surgical steps and postoperative care plan. Patients' demographic and surgical parameters were recorded. The main outcome measures included superficial wound infection, deep infection and overall infection.

RESULTS

The incidence of overall SSI was 4.66% in the B group and 1.59% in the P group. The univariate analysis revealed a significant correlation with DM and irrigation amount per hour during surgery but not age, BMI, smoking, operative duration, fusion level, or blood loss. We determined the optimal irrigation amount during surgery as 1,400 mL per hour based on the receiver operating characteristic (ROC) curve (sensitivity, 92.3%; specificity, 44.1%). This was statistically significant (p=.033) with an odds ratio of 9.284 (95% confidence interval 1.2-72.0). In the analysis of surgical factors, the infection group had a significantly lower irrigation amount during surgery. To summarize, patients with diabetes and those receiving less than 1,400 mL of NS/hour had a higher likelihood of developing SSI.

CONCLUSIONS

We observed that diabetes and lower volume of intraoperative irrigation were both risk factors for postoperative SSI following degenerative lumbar spine surgery. To reduce SSI in lumbar spine surgery, intra-wound irrigation with more than 1,400 mL/h of NS was recommended.

Prophylactic Intrawound Antibiotics Significantly Reduce the Risk of Deep Infections in Fracture Fixation: Subgroup Meta-analyses of the Type of Fracture, Antibiotics, and Organism

OBJECTIVES

To analyze the efficacy of subgroups of various intrawound local antibiotics in reducing the rate of fracture-related infections.

DATA SOURCES AND STUDY SELECTION

PubMed, MEDLINE via Ovid, Web of Science, Cochrane database, and Science Direct were searched for articles in English on July 5, 2022, and December 15, 2022.

STUDY SELECTION

All clinical studies comparing the incidence of fracture-related infection between the administration of prophylactic systemic and topical antibiotics in fracture repair were analyzed.

DATA EXTRACTION

Cochrane collaboration's assessment tool and the methodological bias and the methodological index for nonrandomized studies were used to detect bias and evaluate the quality of included studies, respectively.

DATA SYNTHESIS

RevMan 5.3 software (Nordic Cochrane Centre, Denmark) was used to conduct the meta-analyses and generate forest plots.

CONCLUSIONS

From 1990 to 2021, 13 studies included 5309 patients. Nonstratified meta-analysis showed that intrawound administration of antibiotics significantly decreased the overall incidence of infection in both open and closed fractures, regardless of the severity of open fracture and antibiotics class [OR = 0.58, ( P = 0.007)] [OR = 0.33, ( P < 0.00001)], respectively. The stratified analysis revealed that prophylactic intrawound antibiotics significantly lowered infection rate in open fracture patients with Gustilo-Anderson type I (OR = 0.13, P = 0.004), type II (OR = 0.29, P = 0.0002), type III (OR = 0.21, P < 0.00001), when either tobramycin PMMA beads (OR = 0.29, P < 0.00001) or vancomycin powder (OR = 0.51, P = 0.03) was applied. This study demonstrates prophylactic administration of intrawound antibiotics significantly decreases the overall incidence of infection in all subgroups of surgically fixated fractures but does not affect the patient's length of hospital stay.

LEVEL OF EVIDENCE

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

Topical streptomycin irrigation of lesions to prevent postoperative site infections in spinal tuberculosis: a retrospective analysis

PURPOSE

In spinal tuberculosis surgery, topical administration of drugs to the lesion is a preventive treatment measure. The aim is to achieve better bacterial inhibition and to prevent complications. As one of the most common complications after spinal tuberculosis surgery, many factors can lead to surgical site infection (SSI). No definitive reports of local streptomycin irrigation of the lesion and SSI of spinal tuberculosis have been seen. This study analyzed data related to surgical site infections (SSI) after the treatment of spinal tuberculosis using this regimen.

METHODS

In this study, 31 were in the observation group (streptomycin flush) and 34 in the control group (no streptomycin flush). All patients received the same standard of perioperative care procedures. General information, operative time, intraoperative bleeding, ESR and CRP at one week postoperatively, time on antibiotics, total drainage, days in hospital, incision infection rate and secondary debridement rate were compared between the two groups.

RESULTS

Patients in both groups completed the surgery successfully. The ESR and CRP levels in the observation group were lower than those in the control group one week after surgery (p < 0.05); the duration of postoperative antibiotics and hospital stay were lower than those in the control group (p < 0.05); the incidence of SSI in the two groups was 5.88% and 6.45% respectively, with no significant difference (p > 0.05).

CONCLUSION

The use of topical streptomycin irrigation of the lesion during surgical procedures for spinal tuberculosis had no significant effect on the incidence of SSI, however, it helped to control the level of infection in the postoperative period and reduced the length of time patients had to use postoperative antibiotics and the number of days they stayed in hospital. Future prospective randomised controlled trials in more centres and larger samples are recommended.

Vancomycin Flushing Syndrome After the Use of Vancomycin-Impregnated Bone Graft During Spine Surgery: A Case Report

CASE

Intrawound vancomycin in spine surgery is a common clinical practice. We report a case of a 14-year-old adolescent girl undergoing surgery for scoliosis correction who developed features of vancomycin flushing syndrome after the use of vancomycin-impregnated bone graft. After resuscitation, she was extubated and had an uneventful postoperative recovery. At 1-year follow-up, she is back to her routine without any sequelae of the intraoperative event.

CONCLUSION

The use of intrawound vancomycin can result in life-threatening reactions. With the increase in its use, the anesthetist and the surgeon must be aware of such complications.

Intrawound low-dose vancomycin is superior to high-dose in controlling the risk of wound dehiscence in spine surgeries

Wound complications in spine surgeries are common and serious. This study aimed to determine the risk of wound dehiscence with a low-dose of intrawound vancomycin compared to that with a high-dose and no-vancomycin and its effectiveness in the prevention of surgical site infection. Patients were categorized into 3 groups. The first group did not receive any intrawound vancomycin. In the second, patients received a high-dose of vancomycin (1 g). The third group included patients who received a low-dose of intrawound vancomycin (250 mg). Patient demographics, clinical data, and surgical data were also collected. Multivariate linear regression analysis was used to examine factors associated with dehiscence or infection. Of the 391 patients included in our study, 56 (14.3%) received a high-dose of intrawound vancomycin, 126 (32.2%) received a low-dose, and 209 (53.5%) did not receive any treatment. The overall incidence of wound dehiscence was 6.14% (24 out of 391 patients). Wound dehiscence was significantly higher (P = .039) in the high-dose vancomycin group than in the low-dose vancomycin group. The overall incidence of postoperative infection was 2.05% (8 patients) and no statistically significant differences were observed between the low-dose and high-dose vancomycin groups. Patients with higher body mass index were more likely to experience wound dehiscence and postoperative infection, irrespective of the dose of vancomycin used. The use of low-dose intrawound vancomycin (250 mg) resulted in less wound dehiscence compared with high-dose vancomycin. Further trials are required to evaluate the effectiveness of the low-dose in preventing postoperative infections.

Quantitative evaluations of variations using the population mean as a baseline for bioinformatics interpretation

Objective

The purpose of this study were to establish a model of quantitative evaluation that uses the population mean as a baseline of variations and describe variations derived from different types and systems using new concepts.

Methods

The observed datasets, including measurement data and relative data, were transformed to 0-1.0 using the population mean. Datasets derived from different types (same category of dataset, different categories of datasets, and datasets with the same baseline) were transformed using different methods. The 'middle compared index' (MCI) was used to describe the change in magnitude as follows: [a/(a+b)+(1-b)/(2-a-b)-1]^1.7, where 'a' represents the number after the magnitude change and 'b' represents the number before the magnitude change. Actual data were used to observe the MCI's ability to evaluate variations quantitatively.

Results

When the value before the magnitude change was equal to that after the magnitude change, the MCI was equal to 0; when the value before the magnitude change was equal to 0 and that after the magnitude change was equal to 1, the MCI was equal to 1. This implies the MCI is valid. When the value before the magnitude change was 0 and that after the magnitude change was 0.5, or when the value before the magnitude change was 0.5 and that after the magnitude change was 1.0, each MCI was approximately equal to 0.5. The values derived from the absolute, ratio, and MCI methods were different, indicating that the MCI is an independent index.

Conclusion

The MCI perfectly performs as an evaluation model using the population mean as the baseline, and it may be more a reasonable index than the ratio or absolute methods. The MCI increases our understanding of quantitative variations in evaluation measures of association using new concepts.

Evidence for Local Antibiotics in the Prevention of Infection in Orthopaedic Trauma

Prevention of fracture-related infection (FRI) remains a substantial challenge in orthopaedic trauma care. There is evolving evidence to support the use of local antibiotics for both the prevention and treatment of musculoskeletal infection. Local antibiotics can achieve higher local tissue concentrations with a lower risk of systemic complications compared to intravenously administered antibiotics. These antibiotics may be administered in powder or liquid form without carrier, or if sustained release is desired, using a carrier. Polymethylmethacrylate (PMMA), ceramics, and hydrogels are examples of antibiotic carriers. Unlike PMMA, ceramics and hydrogels have the advantage of not requiring a second surgery for removal. The VANCO trial supported the use of powdered vancomycin in high-risk fracture cases for the reduction of Gram-positive infections; although, data is limited. Future studies will evaluate the use of aminoglycoside antibiotics to address Gram-negative infection prevention. While theoretical concerns exist with the use of local antibiotics, available studies suggest local antibiotics are safe with a low-risk of adverse effects.

Do Intrawound Antibiotics Reduce the Incidence of Surgical Site Infections in Pelvic and Lower-Limb Trauma Surgery? A Systematic Review and Meta-analysis

OBJECTIVES

To analyze the efficacy of intraoperative topical antibiotics in reducing the incidence of postoperative surgical site infections in pelvic and lower-limb trauma orthopaedic surgery.

DATA SOURCES

A search of Ovid MEDLINE, PubMed, and Embase was conducted for English language studies published from 1946 through September 3, 2021, using relevant keywords.

STUDY SELECTION

Included studies were randomized controlled trials, cohort studies, or case-control studies reporting on the rate of surgical site infections in adult patients (age 16 and older) who underwent surgical fixation of lower-limb or pelvic traumatic fractures, including both open and closed fractures, with topical intraoperative antibiotics applied to the surgical site before wound closure.

DATA EXTRACTION

Studies were evaluated using the Joanna Briggs Institute Critical Appraisal Checklist for analytical cross-sectional studies. The risk of bias was assessed using the ROBINS-I and Cochrane risk-of-bias tools.

DATA SYNTHESIS

A meta-analysis was conducted using the inverse variance method and random-effects model to assess effect significance and study heterogeneity.

CONCLUSIONS

Seven studies were included in the systematic review. Results of the meta-analysis suggested a potential 23% reduction in the odds of developing a deep surgical site infection in patients treated with intraoperative antibiotic powder compared with those managed with intravenous antibiotics alone (odds ratio 0.77, 95% confidence interval 0.52-1.13), although the results did not reach statistical significance. Further powered studies including randomized controlled trials would be of great value to validate the results suggested in this study and inform best practice intraoperative antibiotic prophylaxis in pelvic and lower-limb trauma surgery.

LEVEL OF EVIDENCE

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

Efficacy of Povidone Iodine Solution in the Prevention of Surgical Site Infections in Minimally Invasive Instrumented Spinal Fusion Surgery

STUDY DESIGN

A retrospective case-controlled study.

OBJECTIVES

To evaluate overall infection rate and adverse event after harvesting bone graft soaking and surgical wound irrigation by povidone iodine solution (PVI) in the minimally invasive instrumented spinal fusion surgery. In order to reduce the rate of surgical site infection in spinal surgery, surgical wound irrigation by povidone iodine solution has been well-established. However, the efficacy of autologous bone graft soaking by PVI has not been evaluated before.

METHODS

This is a retrospective cohort study. 120 patients were enrolled in the PVI group and compared with 124 patients in the historical cohort. In the PVI group, the harvesting autologous bone graft was soaking and the surgical wound was also irrigated by diluted PVI solution. The outcome measures were overall infection rate, superficial wound infection and deep infection. In addition, the delayed union of the fusion mass was also evaluated through the radiograph evaluation.

RESULTS

Both groups shared similar patient demographics instead of body mass index. The use of PVI solution had decreased the overall infection rate (0% versus 4.03%, p = 0.026) and deep infection rate (0% versus 3.23%, p = 0.047). In addition, there was no delayed bone healing in the PVI group after autologous bone graft soaking.

CONCLUSIONS

In this study, we conclude that harvested autologous bone graft after PVI soaking in spinal fusion surgery can decrease the incidence of deep infection.

Use of Vancomycin Powder in Spinal Deformity Surgery in Cerebral Palsy Patients is Associated With Proteus Surgical Site Infections

PURPOSE

Surgical site infection (SSI) rates in pediatric spinal deformity surgery for cerebral palsy (CP) patients are higher than that in idiopathic scoliosis. The use of vancomycin powder is associated with decreased risk of SSI in neuromuscular patients. Prior studies in adult and pediatric early-onset scoliosis patients have shown that vancomycin powder alters microbacterial profile in patients that develop SSI. However, the effects of topical vancomycin powder on microbiology in spinal deformity surgery for CP patients has not been studied.

METHODS

An international multicenter database of CP neuromuscular scoliosis patients was used in this retrospective cohort study. All patients that underwent posterior spinal instrumented fusion for CP neuromuscular scoliosis from 2008 to 2019 were queried, and 50 cases complicated by postoperative SSI were identified. Intraoperative antibiotic details were documented in 49 cases (98.0%). Microbiology details were documented in 45 cases (91.8%). Microbiology for patients that received topical vancomycin powder were compared with patients that did not. A multivariate regression model was used to control for potential confounders.

RESULTS

There were 45 patients included in this study. There were 27 males (60.0%) and 18 females (40.0%). Mean age at surgery was 14.8±2.4 years. There were 24 patients that received topical vancomycin powder (53.3%). The mean time from index surgery to SSI was 4.3±11.3 months.On univariate analysis of microbiology cultures by vancomycin powder cohort, there were no significant differences in culture types. Proteus spp. trended on significance with association with vancomycin powder use (P=0.078). When controlling for potential confounders on multivariate analysis, intraoperative topical vancomycin powder was associated with increased risk for proteus infection (adjusted odds ratio: 262.900, 95% confidence interval: 1.806-38,267.121, P=0.028).

DISCUSSION

In CP patients undergoing pediatric spinal deformity surgery, the use of vancomycin powder was independently associated with increased risk for proteus infections. Further study into antibiotic regimens for spinal deformity surgery in the CP population should be performed.

LEVEL OF EVIDENCE

Level III-retrospective cohort study.

Effectiveness of Oral Antibiotic Therapy in Prevention of Postoperative Wound Infection Requiring Surgical Washout In Spine Surgery

BACKGROUND

Surgical site infections (SSIs) after spine surgery are a significant cause of morbidity. Surgeons often prescribe oral antibiotics in the postoperative setting for infected-appearing wounds to prevent reoperation for infection; however, the efficacy of this practice has not been well studied.

METHODS

Neurosurgical spine patients with clinical concerns for SSI at the University of Pennsylvania were retrospectively studied from 2014 to 2018. Clinical predictors of 90-day reoperation for infection despite antibiotic treatment and variables that influenced antibiotic prescription were analyzed.

RESULTS

Three hundred and ninety-two patients were included in the study. Preoperative albumin level, days elapsed to antibiotic prescription from index surgery, preoperative hemoglobin level, surgical location, gender, discharge disposition, and level of wound concern were significant predictors of reoperation for infection on bivariate analysis. Days elapsed to antibiotic prescription, surgical location, and level of wound concern remained significant after multivariable logistic regression. Variables that significantly predicted prescription of an antibiotic include length of stay, cerebrospinal fluid leak, race, and level of wound concern. Length of stay, race, and level of wound concern remained significant after multivariable analysis.

CONCLUSIONS

Wound infection remains a challenging problem in spine surgery and it is reasonable to perform early reoperation in patients with high clinical concerns for infection, because bacterial isolates are often resistant to common oral antibiotics. Patients with wounds with low clinical concerns for infection may undergo a trial of oral antibiotics; however, duration of treatment should not be prolonged.

Successful prolonged cardiopulmonary resuscitation after intraoperative cardiac arrest due to povidone-iodine allergy: A case report

BACKGROUND

Iodophor (povidone-iodine) is widely used clinically because of its broad-spectrum antibacterial effects. Although extremely rare, it may cause anaphylactic shock, which itself carries the life-threatening risk of cardiac arrest.

CASE SUMMARY

We present a case in which a patient with postoperative infection went into anaphylactic shock and cardiac arrest caused by povidone-iodine during secondary surgery. The patient was successfully resuscitated by 2 h of cardiopulmonary resuscitation.

CONCLUSION

This is the first known case of cardiac arrest caused by povidone-iodine allergy.

Prophylactic Topical Antibiotics in Fracture Repair and Spinal Fusion

INTRODUCTION

The objective of this systematic review with meta-analysis is to determine whether prophylactic local antibiotics prevent surgical site infections (SSIs) in instrumented spinal fusions and traumatic fracture repair. A secondary objective is to investigate the effect of vancomycin, a common local antibiotic of choice, on the microbiology of SSIs.

METHODS

An electronic search of PubMed, EMBASE, and Web of Science databases and major orthopedic surgery conferences was conducted to identify studies that (1) were instrumented spinal fusions or fracture repair and (2) had a treatment group that received prophylactic local antibiotics. Both randomized controlled trials (RCTs) and comparative observational studies were included. Meta-analysis was performed separately for randomized and nonrandomized studies with subgroup analysis by study design and antibiotic.

RESULTS

Our review includes 44 articles (30 instrumented spinal fusions and 14 fracture repairs). Intrawound antibiotics significantly decreased the risk of developing SSIs in RCTs of fracture repair (RR 0.61, 95% CI: 0.40-0.93, I 2 = 32.5%) but not RCTs of instrumented spinal fusion. Among observational studies, topical antibiotics significantly reduced the risk of SSIs in instrumented spinal fusions (OR 0.34, 95% CI: 0.27-0.43, I 2 = 52.4%) and in fracture repair (OR 0.49, 95% CI: 0.37-0.65, I 2 = 43.8%). Vancomycin powder decreased the risk of Gram-positive SSIs (OR 0.37, 95% CI: 0.27-0.51, I 2 = 0.0%) and had no effect on Gram-negative SSIs (OR 0.95, 95% CI: 0.62-1.44, I 2 = 0.0%).

CONCLUSIONS

Prophylactic intrawound antibiotic administration decreases the risk of SSIs in fracture surgical fixation in randomized studies. Therapeutic efficacy in instrumented spinal fusion was seen in only nonrandomized studies. Vancomycin appears to be an effective agent against Gram-positive pathogens. There is no evidence that local vancomycin powder is associated with an increased risk for Gram-negative infection.

Use of Vancomycin Powder in the Surgical Treatment of Early Onset Scoliosis Is Associated With Different Microbiology Cultures After Surgical Site Infection

BACKGROUND

The use of vancomycin powder has been shown to decrease risk of surgical site infection (SSI) in early onset scoliosis (EOS). While there is potential benefit in SSI reduction, there is also theoretical risk in creating increased bacterial resistance to standard treatment regimens. However, the effects of topical vancomycin powder on microbiology in these patients has not been studied.

METHODS

A multicenter database for EOS patients was retrospectively analyzed. All patients that underwent surgical treatment with traditional growing rods, magnetically controlled growing rods, vertical expandable prosthetic titanium rib, and Shilla for EOS performed after 2010 were identified (n=1115). Patients that sustained at least 1 SSI after guided growth surgery were assessed (n=104, 9.3%). Patients with culture and antibiotic details were included (n=55). Patients that received vancomycin powder at index surgery were compared with patients that did not. A multivariate regression model was used to control for potential confounders.

RESULTS

There were 55 patients included in this study, including 26 males (47%) and 29 females (53%). Mean age at index surgery was 7.2±6.9 years. Vancomycin powder was utilized in 18 cases (33%). Mean time from index surgery to SSI was 2.0±1.3 years. There were 2 cases of wound dehiscence (4%), 7 cases of superficial infection (13%), and 46 cases of deep infection (84%).There were significant differences in overall microbiology results between vancomycin and no vancomycin cohorts (P=0.047). On univariate analysis, the vancomycin powder cohort had a significantly high incidence of cultures without growth (n=7, 39% vs. n=4, 11%, relative risk: 2.063, 95% confidence interval: 0.927-4.591, P=0.028). This association remained significant on multivariate analysis (adjusted odds ratio: 9.656, 95% confidence interval: 1.743-53.494, P=0.009).

CONCLUSIONS

In EOS patients undergoing procedures complicated by SSI, the use of vancomycin powder was independently associated with increased risk of no culture growth. Surgeons and infectious disease physicians should be aware and adjust diagnostic and treatment strategies appropriately.

LEVEL OF EVIDENCE

Level III-retrospective cohort study.

Effectiveness of diluted povidone-iodine lavage for preventing periprosthetic joint infection: an updated systematic review and meta-analysis

Background

Of the several methods used to prevent surgical site infection (SSI), diluted povidone-iodine (PI) lavage is used widely. However, the clinical utility of PI for preventing periprosthetic joint infection (PJI) remains controversial. The aim of this study was to perform a systematic review and meta-analysis of the utility of dilute PI lavage for preventing PJI in primary and revision surgery.

Methods

This study was conducted in accordance with the PRISMA checklist for systematic reviews and meta-analyses. A comprehensive literature search of PubMed, CINAHL, ClinicalTrials.gov, and Cochrane Library databases was performed. The results are summarized qualitatively and as a meta-analysis of pooled odds ratios with 95% confidence intervals (95% CIs). Heterogeneity of treatment effects among studies was classified as low, moderate, or high, corresponding to I² values of < 25%, 25–50%, and > 50%. A random effects model was applied in cases of high heterogeneity; otherwise, the fixed effects model was applied. Subgroup analyses were conducted to identify potential sources of heterogeneity.

Results

After the screening and eligibility assessment process, eight studies were finally extracted for analysis. Overall, the results showed that PI had no significant effect on PJI with ununified control group. However, subgroup analysis of studies with a saline control group revealed an odds ratio of 0.33 (95% CI, 0.16–0.71) for the PI group, suggesting a significant effect for preventing PJI.

Conclusion

The systematic review and meta-analysis of the current literature demonstrates that diluted PI lavage is significantly better than saline solution lavage for preventing PJI.

Level of evidence

Level I, Systematic review and meta-analysis.

Use of Vancomycin Mixed Bone Graft and Vancomycin Mixed Saline Wash Before Wound Closure Reduces the Rate of Infection in Lumbar Spine Fusion Surgery

This study aims to evaluate whether surgical site vancomycin mixed in bone grafts and local vancomycin mixed in normal saline wash before wound closure decrease the infection rates in patients undergoing lumbar spinal instrumentation and posterolateral fusion. A retrospective study was performed on cases between 2017 and 2019, who underwent lumbar spine instrumentation and posterolateral fusion for lumbar canal stenosis or listhesis. The routine prophylactic procedures were performed in all patients as per institutional protocol. Patients' records were analysed and categorised into two groups, the vancomycin group (VG), where vancomycin mixed in bone graft and normal saline wash was used at the surgical site, and the control group (CG), where vancomycin was not used. The study included 63 patients, 31 in VG and 32 in CG. There is no statistical difference in age, sex, and diabetes mellitus in both groups. A total of seven cases were infected, six in CG (6/32) and one in VG (1/31). Out of six infections in CG, three patients had diabetes and four infected cases underwent surgery for debridement. In VG, the only single case got infected and treated with intravenous antibiotics. We found that the use of vancomycin added to the bone graft and normal saline in posterior lumbar spinal instrumentation and posterolateral fusion is associated with significantly lower rates of infection (p value=0.049).

Antimicrobial laser-activated sealants for combating surgical site infections

Surgical-site infections (SSIs) occur in 2-5% of patients undergoing surgery in the US alone, impacting 300 000-500 000 lives each year, and presenting up to 11 times greater risk of death compared to patients without SSIs. The most common cause of SSI is Staphylococcus aureus, and methicillin-resistant S. aureus (MRSA) is the most common pathogen in community hospitals. Current clinical devices used for approximating incisions and traumatic lacerations include sutures, adhesives, tapes, or staples with or without antimicrobial incorporation. However, current closure technologies may not provide adequate protection against infection, are susceptible to wound dehiscence, and can result in delayed biomechanical recoveries. Laser-activated tissue repair is a sutureless technique in which chromophore-loaded sealants convert laser light energy to heat in order to induce rapid tissue sealing. Here, we describe the generation and evaluation of laser-activated sealant (LASE) biomaterials, in which, indocyanine green (ICG), an FDA-approved dye, was embedded in a silk fibroin matrix and cast into films as wound sealants. Silk-ICG films were subjected to different near-infrared (NIR) laser powers to identify temperatures optimal for laser sealing of soft tissues. A mathematical model was developed in order to determine the photothermal conversion efficiency of LASEs following laser irradiation. NIR laser activation of silk-ICG LASEs increased the recovery of skin biomechanical strength compared to sutured skin in full-thickness incisional wounds in immunocompetent mice, and live animal imaging indicated persistence of silk-ICG LASEs over several days. LASEs loaded with the antibiotic vancomycin demonstrated higher efficacies for combating MRSA infections in a mouse model of surgical site infection compared to antibacterial sutures. Our results demonstrate that LASEs can be loaded with antimicrobial drugs and may serve as new multifunctional biomaterials for rapid tissue sealing, repair and surgical site protection following surgery.

The Diagnostic Value of Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography for the Detection of Surgical Site Infection after Spine Surgery

STUDY DESIGN

Retrospective case series.

OBJECTIVE

The purpose of this study was to assess the diagnostic yield of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) for surgical site infection (SSI) after spine surgery.

SUMMARY OF BACKGROUND DATA

Diagnosis of SSI in the spine based on F-18 FDG PET/CT requires experienced nuclear medical physicians for a detailed analysis of F-18 FDG distribution pattern. It has also been reported that increases in the maximal standardized uptake values of F-18 FDG (SUVmax) closely correlated with SSI, suggesting potential of more objective and quantitative diagnosis.

METHODS

We assessed the diagnostic yield of F-18 FDG PET/CT (pattern-based diagnosis by nuclear medical physicians and SUVmax-based diagnosis) for SSI in 52 subjects who underwent spine surgery. The 52 subjects included 11 nonimplant and 41 implant cases. F-18 FDG PET/CT was performed in 33 and 19 cases in early (≤12 weeks after the surgery) and late (>12 weeks) phases, respectively. The final diagnosis of SSI was based on the results of pathogen identification, plain radiography, and CT and/or magnetic resonance imaging or response to antibiotics and/or reoperation.

RESULTS

SUVmax-based diagnosis was performed with a cut off value of 5.0 as determined by receiver operating characteristic analysis. Both pattern-based and SUVmax-based diagnoses demonstrated excellent diagnostic yields with high sensitivity (97% and 90%), specificity (100% and 100%), and accuracy (98% and 94%). High diagnostic yields (accuracy of ≥90%) were consistently observed irrespective of presence or absence of implantation or interval between surgery and F-18 FDG PET/CT.

CONCLUSION

F-18 FDG PET/CT can be the procedure of choice for investigation of SSI in the spine when other imaging fails to provide a definitive diagnosis.Level of Evidence: 4.

Negative pressure wound therapy does not diminish efficacy of topical antibiotic powder in a preclinical contaminated wound model

AIMS

High-energy injuries can result in multiple complications, the most prevalent being infection. Vancomycin powder has been used with increasing frequency in orthopaedic trauma given its success in reducing infection following spine surgery. Additionally, large, traumatic injuries require wound coverage and management by dressings such as negative pressure wound therapy (NPWT). NPWT has been shown to decrease the ability of antibiotic cement beads to reduce infection, but its effect on antibiotic powder is not known. The goal of this study was to determine if NPWT reduces the efficacy of topically applied antibiotic powder.

METHODS

Complex musculoskeletal wounds were created in goats and inoculated with a strain of Staphylococcus aureus modified to emit light. Six hours after contaminating the wounds, imaging, irrigation, and debridement and treatment application were performed. Animals received either vancomycin powder with a wound pouch dressing or vancomycin powder with NPWT.

RESULTS

There were no differences in eradication of bacteria when vancomycin powder was used in combination with NPWT (4.5% of baseline) compared to vancomycin powder with a wound pouch dressing (1.7% of baseline) (p = 0.986), even though approximately 50% of the vancomycin was recovered in the NPWT exudate canister.

CONCLUSION

The antimicrobial efficacy of the vancomycin powder was not diminished by the application of NPWT. These topical and locally applied therapies are potentially effective tools that can provide quick, simple treatments to prevent infection while providing coverage. By reducing the occurrence of infection, the recovery is shortened, leading to an overall improvement in quality of life. Cite this article: Bone Joint Res 2021;10(2):149-155.

Impact of intrawound vancomycin powder on prevention of surgical site infection after posterior spinal surgery

OBJECTIVE

Surgical site infection (SSI) after posterior spinal surgery is one of the severe complications that may occur despite administration of prophylactic antibiotics and the use of intraoperative aseptic precautions. The use of intrawound vancomycin powder for SSI prevention is still controversial, with a lack of high-quality and large-scale studies. The purpose of this retrospective study using a propensity score-matched analysis was to clarify whether intrawound vancomycin powder prevents SSI occurrence after spinal surgery.

METHODS

The authors analyzed 1261 adult patients who underwent posterior spinal surgery between 2010 and 2018 (mean age 62.3 years; 506 men, 755 women; follow-up period at least 1 year). Baseline and surgical data were assessed. After a preliminary analysis, a propensity score model was established with adjustments for age, sex, type of disease, and previously reported risk factors for SSI. The SSI rates were compared between patients with intrawound vancomycin powder treatment (vancomycin group) and those without (control group).

RESULTS

In a preliminary analysis of 1261 unmatched patients (623 patients in the vancomycin group and 638 patients in the control group), there were significant differences between the groups in age (p = 0.041), body mass index (p = 0.013), American Society of Anesthesiologists classification (p < 0.001), malnutrition (p = 0.001), revision status (p < 0.001), use of steroids (p = 0.019), use of anticoagulation (p = 0.033), length of surgery (p = 0.003), estimated blood loss (p < 0.001), and use of instrumentation (p < 0.001). There was no significant difference in SSI rates between the vancomycin and control groups (21 SSIs [3.4%] vs 33 SSIs [5.2%]; OR 0.640, 95% CI 0.368-1.111; p = 0.114). Using a one-to-one propensity score-matched analysis, 444 pairs of patients from the vancomycin and control groups were selected. There was no significant difference in the baseline and surgical data, except for height (p = 0.046), between both groups. The C-statistic for the propensity score model was 0.702. In the score-matched analysis, 12 (2.7%) and 24 (5.4%) patients in the vancomycin and control groups, respectively, developed SSIs (OR 0.486, 95% CI 0.243-0.972; p = 0.041). There were no systemic complications related to the use of vancomycin.

CONCLUSIONS

The current study showed that intrawound vancomycin powder was useful in reducing the risk of SSI after posterior spinal surgery by half, without adverse events. Intrawound vancomycin powder use is a safe and effective procedure for SSI prevention.

Prophylactic postoperative measures to minimize surgical site infections in spine surgery: systematic review and evidence summary

BACKGROUND CONTEXT

There are three phases in prophylaxis of surgical site infections (SSI): preoperative, intraoperative and postoperative. There is lack of consensus and paucity of evidence with SSI prophylaxis in the postoperative period.

PURPOSE

To systematically evaluate the literature, and provide evidence-based summaries on postoperative measures for SSI prophylaxis in spine surgery.

STUDY DESIGN

Systematic review, meta-analysis, evidence synthesis.

METHODS

A systematic review conforming to PRIMSA guidelines was performed utilizing PubMed (MEDLINE), EMBASE, and the Cochrane Database from inception to January 2019. The GRADE approach was used for quality appraisal and synthesis of evidence. Six postoperative care domains with associated key questions were identified. Included studies were extracted into evidence tables, data synthesized quantitatively and qualitatively, and evidence appraised per GRADE approach.

RESULTS

Forty-one studies (nine RCT, 32 cohort studies) were included. In the setting of preincisional antimicrobial prophylaxis (AMP) administration, use of postoperative AMP for SSI reduction has not been found to reduce rate of SSI in lumbosacral spine surgery. Prolonged administration of AMP for more than 48 hours postoperatively does not seem to reduce the rate of SSI in decompression-only or lumbar spine fusion surgery. Utilization of wound drainage systems in lumbosacral spine and adolescent idiopathic scoliosis corrective surgery does not seem to alter the overall rate of SSI in spine surgery. Concomitant administration of AMP in the presence of a wound drain does not seem to reduce the overall rate of SSI, deep SSI, or superficial SSI in thoracolumbar fusion performed for degenerative and deformity spine pathologies, and in adolescent idiopathic scoliosis corrective surgery. Enhanced-recovery after surgery clinical pathways and infection-specific protocols do not seem to reduce rate of SSI in spine surgery. Insufficient evidence exists for other types of spine surgery not mentioned above, and also for non-AMP pharmacological measures, dressing type and duration, suture and staple management, and postoperative nutrition for SSI prophylaxis in spine surgery.

CONCLUSIONS

Despite the postoperative period being key in SSI prophylaxis, the literature is sparse and without consensus on optimum postoperative care for SSI prevention in spine surgery. The current best evidence is presented with its limitations. High quality studies addressing high risk cohorts such as the elderly, obese, and diabetic populations, and for traumatic and oncological indications are urgently required.

Role of local streptomycin in prevention of surgical site infection in TB spine

PURPOSE

Surgical site infection (SSI) continues to be one of the most common post-operative complications in most spine surgeries. Patients with tuberculosis (TB) of spine are more at risk of developing this complication due to a number of reasons. This adds to significant morbidity and economic burden on patients adversely affecting the mental status and quality of life of patients. The aim of this study was to investigate the role of local streptomycin in preventing SSI in patients undergoing surgical management of spinal TB.

METHODS

In total, 56 patients who underwent surgical management for radiologically proven TB spine divided into two groups were included in the study. Group A included 30 patients with no local streptomycin administered intraoperatively, while group B included 26 patients operated in the later part of study with the use of local streptomycin intraoperatively. The two groups were compared and the outcome criteria analysed were SSI rate, length of hospital stay, duration of post-operative antibiotics and need for debridement.

RESULTS

Length of hospital stay (group A: 18.4 ± 6.9 days; group B: 9.7 ± 3.9 days) and duration of post-operative antibiotics (group A: 8.1 ± 1.6 days; group B: 6.2 ± 2.1 days) were significantly higher in group A when compared with group B. SSI rate (group A: 13.34%; group B: 3.84%) and need for debridement (group A: 10%; group B: 3.84%) were higher in group A, but the difference was not statistically significant.

CONCLUSION

Intraoperative administration of local streptomycin significantly reduces the length of hospital stay and duration of antibiotic administration in post-operative period in patients undergoing surgery for TB spine.

Study methodology in trauma care: towards question-based study designs

The randomized controlled trial (RCT) in surgery may not always be ethical, feasible, or necessary to address a particular research question about the effect of a surgical intervention. If so, properly designed and conducted observational (non-randomized) studies may be valuable alternatives for an RCT and produce credible results. In this paper, we discus differences between RCTs and observational studies and differentiate between three types of comparisons of surgical interventions. We assert that results of different designs should be regarded as complementary to each other when evaluating surgical interventions. Criteria for credible observational research are presented to provide guidance for future observational research of surgical interventions. We argue that the research question that is being asked should guide the discussion about the value of a particular study design.

The efficacy of intrawound vancomycin powder and povidone-iodine irrigation to prevent surgical site infections in complex instrumented spine surgery

BACKGROUND CONTEXT

Surgical site infections (SSIs) are notorious complications in spinal surgery and cause substantial patient morbidity. Intraoperative decontamination of the wound with povidone-iodine irrigation or vancomycin powder has gained attention lately, but the efficacy of either intervention is unclear.

PURPOSE

To determine the efficacy of intrawound povidone-iodine or vancomycin in reducing the incidence of deep- and superficial SSIs in instrumented spinal surgery.

STUDY DESIGN/SETTING

Retrospective cohort study.

PATIENT SAMPLE

A retrospective chart review was performed including all consecutive adult patients undergoing open, posterior, instrumented spinal surgery at any level between January 2012 and August 2017.

OUTCOME MEASURES

The presence of SSI was evaluated according to the criteria published by the Centers for Disease Control and Prevention. The SSIs were divided into deep SSIs (below the muscular fascia) and superficial SSIs (above the muscular fascia).

METHODS

A retrospective cohort without intrawound treatment was compared with two separate, consecutive intervention groups. One intrawound group received 1.3g/L povidone-iodine irrigation and the other received 1-2 grams of intrawound vancomycin powder at the end of surgery. Incidence of SSIs, as well as demographic, surgical and patient-related variables were registered and compared between groups. In patients with SSI, additional microbiological data were collected.

RESULTS

In total, 853 patients were included. In the control group (N=257), 25 (9.7%) patients developed a deep and 13 (5.1%) developed a superficial SSI. In the povidone-iodine group (N=217), 21 (9.7%) patients developed a deep and two (0.9%) developed a superficial SSI. Compared with the control group, there was no significant difference in the incidence of deep SSIs (risk ratio [RR]: 1.00, 95% CI 0.57-1.73), although the number of superficial SSIs was reduced significantly (RR 0.18, 95% CI 0.04-0.80). In the vancomycin group (N=379), 19 (5.0%) patients developed a deep and six (1.6%) developed a superficial SSI. Both deep (RR: 0.52, 95% CI 0.29-0.92) and superficial SSIs (RR: 0.31, 95% CI 0.12-0.81) were significantly reduced in the vancomycin group compared with the control group, even when correcting for several risk factors associated with SSIs in a multivariable logistic regression analysis. There were no significant differences in complications between the 3 groups. No gram-negative selection or vancomycin-resistance was seen in the vancomycin group.

CONCLUSIONS

Intrawound application of vancomycin was associated with a significant reduction in both deep and superficial SSIs in instrumented spinal surgery. A 1.3g/L intrawound povidone-iodine solution did not show a reduction in deep SSIs, although a reduction of superficial SSIs was observed.