Implant Retention or Removal for Management of Surgical Site Infection After Spinal Surgery

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.

Interim Use of Antibiotic-Loaded Cement Spacer for Patients with Infected Cervical Fusion

OBJECTIVE

The management of postoperative deep infection after anterior cervical discectomy and fusion (ACDF) remains challenging for spine surgeons. Our institution uses handmade antibiotic-loaded cement spacers to treat these complex cases. This study aimed to determine the efficacy and feasibility of this treatment.

METHODS

This study included 4 patients with deep cervical spine infections after ACDF who underwent our treatment between March 2012 and January 2022. Patients' laboratory data, visual analog scale scores, comorbidities, complications, and neurological status were recorded. Their clinical conditions were also evaluated based on the Neck Disability Index, Japanese Orthopaedic Association score, and Odom criteria.

RESULTS

Infection eradication was achieved in all patients after treatment. The average preoperative visual analog scale score was 7.5 (range: 7-8); this decreased to 1.25 (range: 1-2) at 1 year postoperatively. None of the patients experienced severe complications, such as neurological deterioration or bone graft dislodgement. The Neck Disability Index improved from a preoperative value of 54% (range: 48-60%) to 6% (range: 4-8%) at 1 year postoperatively. The Japanese Orthopaedic Association score improved from a preoperative score of 10.25 (range: 10-11)-14.75 (range: 14-16) at 1 year postoperatively. All patients achieved excellent outcomes based on Odom criteria at 1 year postoperatively.

CONCLUSIONS

Good clinical outcomes were achieved in this study. Although 2-stage surgery is required, this technique could be an alternative for patients with postoperative deep infection after ACDF.

Implant Surface Technologies to Prevent Surgical Site Infections in Spine Surgery

Spine surgeries are occurring more frequently worldwide. Spinal implant infections are one of the most common complications of spine surgery, with a rate of 0.7% to 11.9%. These implant-related infections are a consequence of surface polymicrobial biofilm formation. New technologies to combat implant-related infections are being developed as their burden increases; however, none have reached the market stage in spine surgery. Conferring antimicrobial properties to biomaterials relies on either surface coating (physical, chemical, or combined) or surface modification (physical, chemical, or combined). Such treatment can also result in toxicity and the progression of antimicrobial resistance. This narrative review will discuss "late-stage" antimicrobial technologies (mostly validated in vivo) that use these techniques and may be incorporated onto spine implants to decrease the burden of implant-related health care-acquired infections (HAIs). Successfully reducing this burden will greatly improve the quality of life in spine surgery. Familiarity with upcoming surface technologies will help spine surgeons understand the anti-infective strategies designed to address the rapidly worsening challenge of implant-related health care-acquired infections.

Surgical Site Infection After Posterior Stabilization of the Spine - When do we Have to Remove the Implants?

STUDY DESIGN

Retrospective data analysis.

OBJECTION

The primary objective of this investigation was to analyze if treatment of Postoperative surgical site infections (PSSI) after posterior stabilization of the spine (PS) without radiological signs of screw loosening (RSL) shows a sufficient success rate without implant removal and if there was any difference between early and late PSSI.

SUMMARY OF BACKGROUND DATA

PSSI after PS are usually treated by implant removal and reinstrumentation if loosening of one of more screws is detected. There is presently no conclusive data that shows the success rate of the treatment of PSSI after PS without implant removal if no RSL are perceived.

MATERIALS AND METHODS

All patients who were treated for a PSSI after PS without RSL in a single spine center from 12/2009 to 03/2020 were enrolled in a retrospective analysis. Patients were treated by revision surgery with debridement and irrigation and subsequent antibiotic therapy. Implant removal was performed if the initial treatment did not lead to an improvement in wound healing and normalization of laboratory values. Statistical analysis was performed by Statistical Package for the Social Sciences 25. Descriptive data are given as mean and standard error of mean, a χ 2 test was performed.

RESULTS

Of the 32 enrolled patients, 17 had an early PSSI, 15 a late PSSI. In 71.9% (23/32), the PSSI was treated without implant removal: 12/17 in early PSSI, 11/15 in late PSSI. The difference was not significant ( P >0.05). One patient died, all other patients were discharged from the hospital with no remaining laboratory signs of the infection and with closed soft tissues.

CONCLUSIONS

In our group of patients, the success rate of irrigation and debridement without implant removal was 71.9%. In the light of this data, performing at least two irrigations and debridement before implant removal seems to be a valid treatment option in PSSI after PS if there are no RSL in early and late PSSI.

REVISION RECONSTRUCTION OF THE CERVICAL SPINE IN A PATIENT WITH EARLY DEEP SSI COMPLICATED BY ANGULAR KYPHOSIS: clinical case and literature review

Background. Deep surgical site infection (DSSI) is one of the most severe complications in spinal surgery. The timing and nature of DSSI are the determining criteria in the choice of treatment tactics. Aim. To present a unique clinical case of early deep SSI after ACDF in a patient with multisegmental degenerative spinal canal stenosis, complicated by epidural abscess and angular kyphotic deformity. Angular kyphosis correction, corpectomy of C4-6 and three-column cervical reconstruction were performed in one surgical session. Case presentation. A 57-year-old patient was admitted to the clinic after staged surgical interventions on the cervical spine for multilevel degenerative stenosis of the spinal canal. The primary surgical interventions were complicated by DSSI in the early period after the second surgery with formation of angular kyphosis of the cervical spine. The patient underwent revision one-stage reconstructive intervention to correct the deformity, decompress the spinal canal, and three-column reconstruction of C3-7 segments. Long-term follow-up showed persistent reduction of pain syndrome, improved quality of life and absence of recurrence of DSSI. Conclusion. The presented case illustrates the possibilities of one-stage revision three-column cervical spine reconstruction for correction of sagittal profile, decompression of intracanal neural structures and ensuring stability of operated segments. Use of DSSI treatment algorithms based on Prinz V. and Vajkoczy P. classification contributes to the selection of the optimal tactics of patient management.

Surgical site infection is a major risk factor of pseudarthrosis in adult spinal deformity surgery

BACKGROUND CONTEXT

Despite the evidence in appendicular skeletal surgery, the effect of infection on spinal fusion remains unclear, particularly after Adult Spinal Deformity (ASD) surgery.

PURPOSE

The purpose of this study was to determine the impact of surgical site infection (SSI) in ASD surgery fusion rates and its association with other risks factors of pseudarthrosis.

STUDY DESIGN

We conducted an international multicenter retrospective study on a prospective cohort of patients operated for spinal deformity.

PATIENT SAMPLE

A total of 956 patients were included (762 females and 194 males).

OUTCOME MEASURES

Patient's preoperative characteristics, pre and postoperative spinopelvic parameters, surgical variables, postoperative complications and were recorded. Surgical site infections were asserted in case of clinical signs associated with positive surgical samples. Each case was treated with surgical reintervention for debridement and irrigation. Presence of pseudarthrosis was defined by the association of clinical symptoms and radiological signs of nonfusion (either direct evidence on CT-scan or indirect radiographic clues such as screw loosening, rod breakage, screw pull out or loss of correction). Each iterative surgical intervention was collected.

METHODS

Univariate and multivariate analysis with logistic regression models were performed to evaluate the role of risk factors of pseudarthrosis.

RESULTS

Nine hundred fifty-six surgical ASD patients with more than two years of follow-up were included in the study. 65 of these patients were treated for SSI (6.8%), 138 for pseudarthrosis (14.4%), and 28 patients for both SSI and pseudarthrosis. On multivariate analysis, SSI was found to be a major risk factor of pseudarthrosis (OR=4.4; 95% CI=2.4,7.9) as well as other known risks factors: BMI (OR=1.1; 95% CI=1.0,1.1), smoking (OR=1.6; 95% CI=1.1,2.9), performance of Smith-Petersen osteotomy (OR = 1.6; 95% CI 1.0,2.6), number of vertebrae instrumented (OR=1.1; 95% CI=1.1,1.2) and the caudal level of fusion, with a distal exponential increment of the risk (OR max for S1=6, 95% CI=1.9,18.6).

CONCLUSION

SSI significantly increases the risk of pseudarthrosis with an OR of 4.4.

Does Postoperative Spine Infection Bacterial Gram Type Affect Surgical Debridement or Antibiotic Duration?

STUDY DESIGN

This is a retrospective cohort study.

OBJECTIVE

The aim was to evaluate differences in readmission rates, number of debridements, and length of antibiotic therapy when comparing bacterial gram type following lumbar spinal fusion infections.

SUMMARY OF BACKGROUND DATA

Surgical site infections (SSIs) after spinal fusion serve as a significant source of patient morbidity. It remains to be elucidated how bacterial classification of the infecting organism affects the management of postoperative spinal SSI.

METHODS

Patients who underwent spinal fusion with a subsequent diagnosis of SSI between 2013 and 2019 were retrospectively identified. Patients were grouped based on bacterial infection type (gram-positive, gram-negative, or mixed infections). Poisson regressions analyzed the relationship between the type of bacterial infection and the number of irrigation and debridement (I&D) reoperations, and the duration of intravenous (IV) antibiotic therapy. Significance was set at P <0.05.

RESULTS

Of 190 patients, 92 had gram-positive (G+) infections, 57 had gram-negative (G-) infections, and 33 had mixed (M) infections. There was no difference in 30 or 90-day readmissions for infection between groups (both P =0.051). Patients in the M group had longer durations of IV antibiotic treatment (G+: 46.4 vs. G-: 41.0 vs. M: 55.9 d, P =0.002). Regression analysis demonstrated mixed infections were 46% more likely to require a greater number of debridements ( P =0.001) and 18% more likely to require an increased duration of IV antibiotic therapy ( P <0.001), while gram-negative infections were 10% less likely to require an increased duration of IV antibiotic therapy ( P <0.001) when compared with G- infections.

CONCLUSION

Spinal SSI due to a mixed bacterial gram type results in an increased number of debridements and a longer duration of IV antibiotics required to resolve the infection compared with gram-negative or gram-positive infections.

LEVEL OF EVIDENCE

Level III.

Surgical Site Infection in the Intensive Care Setting After Posterior Spinal Fusion: A Case Series Highlighting the Microbial Profile, Risk Factors, and the Importance of Comorbid Disease Burden

BACKGROUND

Most posterior spinal fusion (PSF) patients do not require admission to an intensive care unit (ICU), and those who do may represent an underinvestigated, high-risk subpopulation.

OBJECTIVE

To identify the microbial profile of and risk factors for surgical site infection (SSI) in PSF patients admitted to the ICU postoperatively.

METHODS

We examined 3965 consecutive PSF patients treated at our institution between 2000 and 2015 and collected demographic, clinical, and procedural data. Comorbid disease burden was quantified using the Charlson Comorbidity Index (CCI). We performed multivariable logistic regression to identify risk factors for SSI, readmission, and reoperation.

RESULTS

Anemia, more levels fused, cervical surgery, and cerebrospinal fluid leak were positively associated with ICU admission, and minimally invasive surgery was negatively associated. The median time to infection was equivalent for ICU patients and non-ICU patients, and microbial culture results were similar between groups. Higher CCI and undergoing a staged procedure were associated with readmission, reoperation, and SSI. When stratified by CCI into quintiles, SSI rates show a strong linear correlation with CCI ( P = .0171, R = 0.941), with a 3-fold higher odds of SSI in the highest risk group than the lowest (odds ratio = 3.15 [1.19, 8.07], P = .032).

CONCLUSION

Procedural characteristics drive the decision to admit to the ICU postoperatively. Patients admitted to the ICU have higher rates of SSI but no difference in the timing of or microorganisms that lead to those infections. Comorbid disease burden drives SSI in this population, with a 3-fold greater odds of SSI for high-risk patients than low-risk patients.

Clinical Outcome of Postoperative Surgical Site Infection in Patients with Posterior Thoracolumbar and Lumbar Instrumentation

OBJECTIVE

Postoperative surgical site infection (SSI) is associated with greater rates of disability, especially in instrumented spinal surgeries. The management of implant-associated surgical site infections (SSI) is challenging. We analyzed the data from our hospital databases to assess the incidence and characteristics related to postoperative surgical site infection (SSI) after posterior thoracolumbar and lumbar instrumentation.

METHODS

Patient demographics, infection characteristics, details of treatment, and perioperative factors were reviewed (Jan 2010 to Dec 2020). The Oswestry disability index (ODI), Patient Health Questionnaire-9 (PHQ-9), and Visual Analog Scale (VAS) scores for back and leg pain were analyzed preoperatively and postoperatively until last follow-up.

RESULTS

Of the 27,881 procedures collected from the databases, 521 were diagnosed with SSI (1.8%), and 191(36.7%) received at least one revision surgery for SSI. Infection rate was significantly higher in patients with lumbar spinal stenosis than those with scoliosis or kyphosis (P<0.01). Methicillin-sensitive Staphylococcus aureus (43.4%) was the most commonly isolated pathogen. The rate of complication secondary to antibiotics treatment was 7.8%, and long-term antibiotic suppression was reported in 15.2% of patients. Instrumentation was retained in 175 patients (91.6%) and all SSIs were controlled without recurrence during the follow-up.

CONCLUSION

Analysis of 27,881 patients showed an average SSI rate of 1.8%. Patients with deep wound SSI can be successfully treated in most cases with retention of instrumentation. Early diagnosis, positive revision surgery with strict irrigation, thorough debridement, and a long-term course of antibiotics are critical for eradicating infection, retaining implants, decreasing morbidity, and achieving wound healing.

Postoperative Spinal Implant Infections (PSII)-A Systematic Review: What Do We Know So Far and What is Critical About It?

STUDY DESIGN

Systematic review.

OBJECTIVES

Postoperative spinal implant infections (PSII) are an increasing challenge in the daily clinical routine. This review summarizes existing knowledge in the field of PSII, including definitions, epidemiology, classifications, risk factors, pathogenesis, symptoms, diagnosis, and treatment.

METHODS

A systematic review was performed using a structured PubMed analysis, based on the PRISMA criteria. The search terminology was set as: "spinal implant associated infection OR spinal implant infection OR spinal instrumentation infection OR peri spinal implant infection." PubMed search was limited to the categories randomized controlled trials (RCT), clinical trials, meta-analysis and (systematic) reviews, whereas case reports were excluded. Studies from January 2000 to December 2020 were considered eligible. A total of 572 studies were identified, 82 references included for qualitative synthesis, and 19 for detailed sub analysis (12 meta-analysis, 7 prospective RCT).

RESULTS

Structural problems in the field of PSII were revealed, including (1) limited level of evidence in clinical studies (missing prospective RCT, metanalyzes), (2) small patient numbers, (3) missing standardized definitions, (4) heterogeneity in patient groups, and (5) redundancy in cited literature.

CONCLUSION

Evidence-based knowledge about spinal implant-associated infections is lacking. All involved medical fields should come together to define the term PSII and to combine their approaches toward research, training, and patient care.

Incidence, Management and Outcome of Delayed Deep Surgical Site Infection Following Spinal Deformity Surgery: 20-Year Experience at a Single Institution

STUDY DESIGN

A retrospective study.

OBJECTIVES

To investigate the incidence, management and outcome of delayed deep surgical site infection (SSI) after the spinal deformity surgery.

METHODS

This study reviewed 5044 consecutive patients who underwent spinal deformity corrective surgery and had been followed over 2 years. Delayed deep SSI were defined as infection involving fascia and muscle and occurring >3 months after the initial procedure. An attempt to retain the implant were initially made for all patients. If the infection failed to be eradicated, the implant removal should be put off until solid fusion was confirmed, usually more than 2 years after the initial surgery. Radiographic data at latest follow-up were compared versus that before implant removal.

RESULTS

With an average follow-up of 5.3 years, 56 (1.1%) patients were diagnosed as delayed deep SSI. Seven (12.5%) patients successfully retained instrumentation and there were no signs of recurrence during follow-up (average 3.4 years). The remaining patients, because of persistent or recurrent infection, underwent implant removal 2 years or beyond after the primary surgery, and solid fusion was detected in any case. However, at a minimum 1-year follow-up (average 3.9 years), an average loss of 9° in the thoracic curve and 8° in the thoracolumbar/lumbar curves was still observed.

CONCLUSIONS

Delayed deep SSI was rare after spinal deformity surgery. To eradicate infection, complete removal of implant may be required in the majority of delayed SSI. Surgeons must be aware of high likelihood of deformity progression after implant removal, despite radiographic solid fusion.

The Current Knowledge on the Pathogenesis of Tissue and Medical Device-Related Biofilm Infections

Biofilm is the trigger for the majority of infections caused by the ability of microorganisms to adhere to tissues and medical devices. Microbial cells embedded in the biofilm matrix are highly tolerant to antimicrobials and escape the host immune system. Thus, the refractory nature of biofilm-related infections (BRIs) still represents a great challenge for physicians and is a serious health threat worldwide. Despite its importance, the microbiological diagnosis of a BRI is still difficult and not routinely assessed in clinical microbiology. Moreover, biofilm bacteria are up to 100–1000 times less susceptible to antibiotics than their planktonic counterpart. Consequently, conventional antibiograms might not be representative of the bacterial drug susceptibility in vivo. The timely recognition of a BRI is a crucial step to directing the most appropriate biofilm-targeted antimicrobial strategy.

Current management trends for surgical site infection after posterior lumbar spinal instrumentation. A systematic review

STUDY DESIGN

Systematic review OBJECTIVE: The objective of this systematic review is to determine the fate of spinal implants when the patients develop postoperative wound infection after posterior instrumental fusion in a degenerative spine.

METHODS

A systematic review of the English-language literature (published between January 2001 and July 2020) was undertaken to identify articles documenting the management strategy for surgical-site infections after posterior lumbar spinal fusion. Studies on pedicle screw fixation after trauma, immunocompromised, metastatic spine disease, and combined anterior/posterior approach were excluded. Two independent reviewers assessed the level of evidence quality using the criteria set by the North American Spine Society, and disagreements were resolved by consensus.

RESULTS

Out of the 3,071 citations identified, 49 met the criteria to undergo full-text review. Outcomes after surgical site infections were studied from a combined pool of 1,150 patients undergone instrumental spinal fusion. The collected data showed that 456 patients (39.97%) had undergone spinal implant removal following SSI while 694 patients (60.03%) had their implants retained until the resolution of SSI. There was an absolute risk reduction of 29% (ARR-0.292) and a relative risk reduction of 50.3% (RRR- 0.503) of implant removal if the patient underwent wound debridement following SSI. The NNT for wound debridement was calculated at 3.31 from our pooled cohort. The absolute risk reduction in implant removal following VAC therapy was 16.6% and relative risk reduction was noted at 40.4%. This led to a high value of NNT at 6.0 patients. There was an absolute risk reduction of 33.5% while a Relative Risk Reduction of 70.7% was estimated in patients undergoing continuous irrigation.

CONCLUSION

Our review of the literature suggests that successful eradication of surgical site infection after posterior lumbar spinal fusion can be achieved by wound debridement or VAC therapy with appropriate antimicrobial coverage in most cases. Implant removal is generally reserved for cases refractory to the other treatment modalities.

Predictive Factors for Successful Treatment of Deep Incisional Surgical Site Infections following Instrumented Spinal Surgeries: Retrospective Review of 1832 Cases

Background: Surgical site infection (SSI) is a major complication in spinal instrumentation that is often difficult to treat. The purpose of this study was to identify and determine prognostic indicators for successful treatment of spine instrumentation SSI. Methods: Retrospectively, spine surgery cases were examined on SSI diagnosis. Post-instrumentation SSI patients were categorized as “Successful” if SSI subsided after single debridement. Patients in whom SSI did not subsided and/or required removal of instrumentation were classified as “Challenging”. We investigated the relation of treatment outcomes to patients and treatment factors. Results: A total of 1832 spinal instrumentation cases were recognized with 44 (2.40%) SSI cases. White blood cell count, C-reactive protein (CRP) levels, causative bacteria (i.e., S. Aureus or MRSA), trauma injury, and early-stage antimicrobial agent sensitivity correlated with treatment prognosis. Multivariate analysis highlighted CRP levels and applying early-stage sensitive antibiotics as potential impactful predictive factors for successful treatment. Conclusions: Our results demonstrated that early selection of sensitive antimicrobial agents is critical and emphasizes the potential for early-stage classification methods such as Gram staining. Additionally, S. Aureus and MRSA SSI formed significantly more challenging infections to treat, thus requiring consideration when deciding on instrumentation retention. These factors offer promising aspects for further large-scale studies.

Factors Affecting Operation Duration in Posterior Spinal Fusion (PSF) Using Dual Attending Surgeon Strategy Among Lenke 1 and 2 Adolescent Idiopathic Scoliosis (AIS) Patients

STUDY DESIGN

This was a retrospective study.

SUMMARY OF BACKGROUND DATA

Prolonged operation duration in adolescent idiopathic scoliosis (AIS) surgery was associated with increased perioperative complications. However, the factors affecting operation duration in AIS surgery were unknown.

OBJECTIVE

The aim of the study was to investigate the factors affecting operation duration in posterior spinal fusion (PSF) surgery using a dual attending surgeon strategy among Lenke 1 and 2 AIS patients.

METHODS

In all, 260 AIS patients with Lenke 1 and 2 curves who underwent PSF were retrospectively reviewed. Preoperative and intraoperative factors affecting operation duration such as age, sex, height, weight, body mass index, Risser grade, Lenke subtypes, number of fusion level, number of screws, screw density, wound length, upper and lowest instrumented vertebrae level, preoperative Cobb angle, and flexibility of the major curve were assessed using univariate and multivariate linear regression analyses. Independent factors were determined when P-value <0.05.

RESULTS

The mean operation duration was 122.2±28.6 minutes. Significant independent factors affecting operation duration in PSF among Lenke 1 and 2 AIS patients were Lenke 2 subtypes (β=8.86, P=0.008), number of screws (β=7.01, P<0.001), wound length (β=1.14, P=0.009), and flexibility of the major curve (β=-0.25, P=0.005). The overall model fit was R2=0.525. Operation duration can be predicted using the formula: (8.86×Lenke subtypes)+(7.01×number of screws)+(1.14×wound length)-(0.25×flexibility)-0.54, where Lenke 2=1 and Lenke 1=0.

CONCLUSION

The factors affecting operation duration in PSF among Lenke 1 and 2 AIS patients were Lenke 2 curves, number of screws, wound length, and curve flexibility. The knowledge of these factors enables the spinal deformity surgeons to plan and estimate the operation duration before AIS surgery.

Biofilm-Related Infections in Gram-Positive Bacteria and the Potential Role of the Long-Acting Agent Dalbavancin

Infections caused by Gram-positive bacteria are a major public health problem due to their increasing resistance to antibiotics. Staphylococcus and Enterococcus species' resistance and pathogenicity are enhanced by their ability to form biofilm. The biofilm lifestyle represents a significant obstacle to treatment because bacterial cells become highly tolerant to a wide range of antimicrobial compounds normally effective against their planktonic forms. Thus, novel therapeutic strategies targeting biofilms are urgently needed. The lipoglycopeptide dalbavancin is a long-acting agent for treating acute bacterial skin and skin structure infections caused by a broad range of Gram-positive pathogens. Recent studies have shown promising activity of dalbavancin against Gram-positive biofilms, including methicillin-resistant S. aureus (MRSA), methicillin-resistant S. epidermidis (MRSE), and vancomycin-susceptible enterococci. This review outlines the mechanisms regulating biofilm development in Staphylococcus and Enterococcus species and the clinical impact of biofilm-related infections. In addition, it discusses the clinical implications and potential therapeutic perspectives of the long-acting drug dalbavancin against biofilm-forming Gram-positive pathogens.

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.

Continuous local antibiotic perfusion for patients with surgical site infection after instrumented spinal surgery; a novel technique to retain the implants

OBJECTIVES

To describe the novel technique of continuous local antibiotic perfusion (CLAP) for a surgical site infection (SSI) after instrumented spinal surgery.

METHODS

CLAP was applied to 4 continuous patients at our institution who developed SSI after instrumented spinal surgery.

RESULTS

All 4 patients were successfully treated and the infection was controlled. The implant was retained in all patients. The duration of CLAP ranged from 2 to 3 weeks. The blood level of the antibiotic used (gentamicin) at 1 week after the initiation of CLAP did not increase in any patient. No other adverse events occurred in any patient. Dramatic improvements in laboratory parameters, including the white blood cell (WBC) counts and C-reactive protein (CRP) levels were seen in every patient at 1 week after the initiation of CLAP.

CONCLUSIONS

CLAP controlled the infection without severe adverse events in all 4 patients, and the implants were retained. Despite its cost and the discomfort of patients, CLAP may become an option for the treatment of SSIs after instrumented spinal surgery. A large number of case series are needed to verify the efficacy of CLAP for patients with SSIs after instrumented spinal surgery.

The Rare Occurrence of Reoperation After Cervical Laminoplasty: A 14-Year Retrospective Review of Reoperative Rates at a Single Institution

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To determine the rate of recurrent or adjacent-level stenosis requiring reoperation after single-door cervical laminoplasty for spondylotic myelopathy at our institution.

SUMMARY OF BACKGROUND DATA

Adjacent-level stenosis requiring reoperation is a commonly evaluated condition for anterior or posterior arthrodesis, however, there are few studies that evaluate adjacent-level stenosis in the case of cervical laminoplasty.

METHODS

Retrospective review of adults undergoing cervical laminoplasty for spondylotic myelopathy between January 2005 and May 2018 at our institution. Demographics, symptom duration, stenotic levels, preoperative and postoperative Medical Research Council motor, American Spinal Injury Association, modified Japanese Orthopaedic Association scores, and Nurick grade were obtained. Postoperative data included presence of C5 palsy, infection rate, alleviation or persistence of symptoms, and rate of recurrent or adjacent-level stenosis.

RESULTS

A total of 102 patients underwent cervical laminoplasty; mean age was 56.7 years (±12.96). Most were men (n=76, 74.5%), with myelopathy (n=64, 63.4%), C4 (n=94, 93.1%), and C5 (n=92, 91.1%) cervical stenosis; mean symptom duration was 55 days (7 d to 2.8 y). Average follow-up was 6.4 months (±3.4). After surgery, there was statistically significant improvement in Nurick grade (3.1±2.2 vs. 2.7±2.4, P=0.002) and modified Japanese Orthopaedic Association score (11.4±3.7 vs. 13.9±3.6, P<0.001); American Spinal Injury Association scores also improved (P<0.001). Rate of postoperative C5 palsy was 7.8% (n=8); postoperative infection rate was 1.96% (n=2). Reoperation rate was 4.9% (n=5); reoperation for recurrent or adjacent-level stenosis was 1.96% (n=2).

CONCLUSIONS

Recurrent or adjacent-level stenosis requiring reoperation after cervical laminoplasty is rare. Longitudinal studies are needed to verify correlation between motion preservation and incidence of adjacent or recurrent stenosis.

LEVEL OF EVIDENCE

Level III-treatment benefits: nonrandomized controlled cohort/follow-up study.

Novel Approaches to Combat Medical Device-Associated BioFilms

Biofilms are aggregates formed as a protective survival state by microorganisms to adapt to the environment and can be resistant to antimicrobial agents and host immune responses due to chemical or physical diffusion barriers, modified nutrient environments, suppression of the growth rate within biofilms, and the genetic adaptation of cells within biofilms. With the widespread use of medical devices, medical device-associated biofilms continue to pose a serious threat to human health, and these biofilms have become the most important source of nosocomial infections. However, traditional antimicrobial agents cannot completely eliminate medical device-associated biofilms. New strategies for the treatment of these biofilms and targeting biofilm infections are urgently required. Several novel approaches have been developed and identified as effective and promising treatments. In this review, we briefly summarize the challenges associated with the treatment of medical device-associated biofilm infections and highlight the latest promising approaches aimed at preventing or eradicating these biofilms.

High Prevalence of Biofilms on Retrieved Implants from Aseptic Pseudarthrosis Cases

INTRODUCTION

Recent literature has associated pseudarthrosis and pedicle screw loosening with subchronic infection at the pedicle of the vertebra. The positive culture results of a previous retrieval analysis show that such patients have a high frequency of bacterial contamination. The objective of this study is to visually capture the architecture of these undiagnosed infections, which have been described in other studies as biofilms on supposedly "aseptic" screw loosening.

METHODS

Explants from 10 consecutive patients undergoing revision spine surgery for pseudarthrosis were collected and fixed in glutaraldehyde solution. Each of these implants was imaged thoroughly by using scanning electron microscopy and x-ray spectroscopy to evaluate the architecture of the biofilm. Additionally, eight patient swabs from tissues around the implants were sent for cultures to assess bacterial infiltration in tissues beyond the biofilm. The implants were also analyzed using energy dispersive x-ray spectroscopy. The exclusion criteria included clinically diagnosed infection (current or previous) and/or mechanical failure of the implant due to falls/accidents.

RESULTS

The study was successful in capturing the visual architecture of the biofilm on retrieved implants. A total of 77% of pseudarthrosis cases presented with loose pedicle screws, which were diagnosed by a preoperative computed tomography scan showing radiolucency along the screw track and were confirmed intraoperatively, and 72% of the cases showed biofilm on explants.

CONCLUSIONS

In the absence of the clinical presentation of infection, impregnated bacteria could form a biofilm around an implant, and this biofilm can remain undetected via contemporary diagnostic methods, including swabbing. Implant biofilm is frequently present in "aseptic" pseudarthrosis cases.

Progress not panacea: vancomycin powder efficacy and dose evaluated in an in vivo mouse model of spine implant infection

BACKGROUND

Intrawound vancomycin powder (VP) has been rapidly adopted in spine surgery with apparent benefit demonstrated in limited, retrospective studies. Randomized trials, basic science, and dose response studies are scarce.

PURPOSE

This study aims to test the efficacy and dose effect of VP over an extended time course within a randomized, controlled in vivo animal experiment.

STUDY DESIGN/SETTING

Randomized controlled experiment utilizing a mouse model of spine implant infection with treatment groups receiving vancomycin powder following bacterial inoculation.

METHODS

Utilizing a mouse model of spine implant infection with bioluminescent Staphylococcus aureus, 24 mice were randomized into 3 groups: 10 infected mice with VP treatment (+VP), 10 infected mice without VP treatment (No-VP), and 4 sterile controls (SC). Four milligrams of VP (mouse equivalent of 1 g in a human) were administered before wound closure. Bioluminescence imaging was performed over 5 weeks to quantify bacterial burden. Electron microscopy (EM), bacterial colonization assays (Live/Dead) staining, and colony forming units (CFU) analyses were completed. A second dosing experiment was completed with 34 mice randomized into 4 groups: control, 2 mg, 4 mg, and 8 mg groups.

RESULTS

The (+VP) treatment group exhibited significantly lower bacterial loads compared to the control (No-VP) group, (p<.001). CFU analysis at the conclusion of the experiment revealed 20% of mice in the +VP group and 67% of mice in the No-VP group had persistent infections, and the (+VP) treatment group had significantly less mean number of CFUs (p<.03). EM and Live/Dead staining revealed florid biofilm formation in the No-VP group. Bioluminescence was suppressed in all VP doses tested compared with sterile controls (p<.001). CFU analysis revealed a 40%, 10%, and 20% persistent infection rate in the 2 mg, 4 mg, and 8 mg dose groups, respectively. CFU counts across dosing groups were not statistically different (p=.56).

CONCLUSIONS

Vancomycin powder provided an overall infection prevention benefit but failed to eradicate infection in all mice. Furthermore, the dose when halved also demonstrated an overall protective benefit, albeit at a lower rate.

CLINICAL SIGNIFICANCE

Vancomycin powder is efficacious but should not be viewed as a panacea for perioperative infection prevention. Dose alterations can be considered, especially in patients with kidney disease or at high risk for seroma.