Management of deep wound infection after posterior lumbar interbody fusion with cages

Remove the infected interbody cage using endoscopy in lumbar spine revision surgery: A case series and technique report

BACKGROUND

Current revision surgery to remove the infected interbody cage following transforaminal lumbar interbody fusion (TLIF) surgery is challenging and traumatic. The purpose of this study is to introduce a novel surgical technique to remove the infected interbody cage for chronic infection.

METHODS

Three patients with chronic infection following TLIF surgery underwent revision surgery. Instrumentations were removed and a spinal endoscope was obliquely inserted to the disc space through the initial annular breach. Under endoscope, the cage was found, released, turned around, and dragged to the posterior edge of the disc space. The cage was then removed without distracting the dural sac and nerve roots. For two cases, appropriately sized structural iliac bone grafts were used for interbody fusion without extra instrumentations.

RESULTS

Using endoscope, the interbody cage was easy to identify and expose without disrupting the dural sac and nerve roots. With various endoscopic tools, the cage was easily released and removed. In this case series, the infected interbody cage was removed within thirty minutes without dural sac rupture and nerve root injury. The infection was controlled after the surgery, and the patients obtained good clinical outcomes. At 6-month follow-up, bony fusion was achieved in two patients who underwent interbody fusion.

CONCLUSIONS

This endoscopy assisted technique simplified the revision surgery for chronic infection followed TLIF surgery, with the advantages of no disruption of the neural tissues, bright surgical field and complete disc debridement.

Vertebral osteomyelitis after spine instrumentation surgery: risk factors and management

BACKGROUND

Vertebral osteomyelitis after spine instrumentation surgery (pVOM) is a rare complication. Most cases of infection occur early after surgery that involve skin and soft tissue and can be managed with debridement, antibiotics, and implant retention (DAIR).

AIM

To identify pVOM risk factors and evaluate management strategies.

METHODS

From a multicentre cohort of deep infection after spine instrumentation (IASI) cases (2010-2016), pVOM cases were compared with those without vertebral involvement. Early and late infections were defined (<60 days and >60 days after surgery, respectively). Multivariate analysis was used to explore risk factors.

FINDINGS

Among 410 IASI cases, 19 (4.6%) presented with pVOM, ranging from 2% (7/347) in early to 19.1% (12/63) in late IASIs. After multivariate analysis, age (adjusted odds ratio (aOR): 1.10; 95% confidence interval (CI): 1.03-1.18), interbody fusion (aOR: 6.96; 95% CI: 2-24.18) and coagulase-negative staphylococci (CoNS) infection (aOR: 3.83; 95% CI: 1.01-14.53) remained independent risk factors for pVOM. Cases with pVOM had worse prognoses than those without (failure rate; 26.3% vs 10.8%; P = 0.038). Material removal was the preferred strategy (57.9%), mainly in early cases, without better outcomes (failure rate; 33.3% vs 50% compared with DAIR). Late cases managed with removal had greater success compared with DAIR (failure rate; 0% vs 40%; P = 0.067).

CONCLUSION

Risk factors for pVOM are old age, use of interbody fusion devices and CoNS aetiology. Although the diagnosis leads to a worse prognosis, material withdrawn should be reserved for late cases or when spinal fusion is achieved.

Osteoconductivity and neurotoxicity of silver-containing hydroxyapatite coating cage for spinal interbody fusion in rats

Background

The use of spinal instrumentation is an established risk factor for postoperative infection. To address this problem, we prepared silver-containing hydroxyapatite coating, consisting of highly osteoconductive hydroxyapatite interfused with silver. The technology has been adopted for total hip arthroplasty. Silver-containing hydroxyapatite coating has been reported to have good biocompatibility and low toxicity. However, no studies about applying this coating in spinal surgery have addressed the osteoconductivity and direct neurotoxicity to the spinal cord of silver-containing hydroxyapatite cages in spinal interbody fusion.

Aim

In this study, we evaluated the osteoconductivity and neurotoxicity of silver-containing hydroxyapatite-coated implants in rats.

Materials & Methods

Titanium (non-coated, hydroxyapatite-coated, and silver-containing hydroxyapatite-coated) interbody cages were inserted into the spine for anterior lumbar fusion. At 8 weeks postoperatively, micro-computed tomography and histology were performed to evaluate the osteoconductivity of the cage. Inclined plane test and toe pinch test were performed postoperatively to assess neurotoxicity.

Results

Micro-computed tomography data indicated no significant difference in bone volume/total volume among the three groups. Histologically, the hydroxyapatite-coated and silver-containing hydroxyapatite-coated groups showed significantly higher bone contact rate than that of the titanium group. In contrast, there was no significant difference in bone formation rate among the three groups. Data of inclined plane and toe pinch test showed no significant loss of motor and sensory function in the three groups. Furthermore, there was no degeneration, necrosis, or accumulation of silver in the spinal cord on histology.

Conclusions

This study suggests that silver-hydroxyapatite-coated interbody cages produce good osteoconductivity and are not associated with direct neurotoxicity.

C-reactive protein to lymphocyte ratio as a new biomarker in predicting surgical site infection after posterior lumbar interbody fusion and instrumentation

Purpose

This study aims to evaluate the potential of C-reactive protein to lymphocyte count ratio (CLR) for the prediction of surgical site infection (SSI) following posterior lumbar interbody fusion (PLIF) and the instrumentation of lumbar degenerative diseases.

Methods

In this retrospective study, we considered patients with a lumbar degenerative disease diagnosis surgically treated by the instrumented PLIF procedure from 2015 to 2021. Patient data, including postoperative early SSI and other perioperative variables, were collected from their respective hospitalization electronic medical records. The receiver operator characteristic curve was constructed to determine the optimal cut-off value for CLR, and the ability to predict SSI was evaluated by the area under the curve (AUC). According to the cut-off value, patients were dichotomized with high- or low-CLR, and between-group differences were compared using univariate analysis. The independent impact of CLR on predicting SSI was investigated by multivariate logistics regression analysis.

Results

A total of 773 patients were included, with 26 (3.4%) developing an early SSI post-operation. The preoperative CLR was 11.1 ± 26.1 (interquartile range, 0.4–7.5), and the optimal cut-off was 2.1, corresponding to a sensitivity of 0.856, a specificity of 0.643, and an AUC of 0.768 (95% CI, 0.737–0.797). CLR demonstrated a significantly improved prediction ability than did lymphocyte count (P = 0.021) and a similar ability to predict an infection as C-response protein (P = 0.444). Patients with a high CLR had a significantly higher SSI incidence than those with a low CLR (7.6% vs. 0.8%, P < 0.001). After adjustment for numerous confounding factors, CLR ≥ 2.1 was associated with an 11.16-fold increased risk of SSI, along with other significant variables, i.e., diabetes, preoperative waiting time, and surgical duration.

Conclusion

A high CLR exhibited an improved ability to predict incident SSI and was associated with a substantially increased risk of SSI following instrumented PLIF. After better-design studies verified this finding, CLR could potentially be a beneficial tool in surgical management.

Biomechanical Comparison of Salvage Pedicle Screw Augmentations Using Different Biomaterials

Allograft bone particles, hydroxyapatite/β-hydroxyapatite-tricalcium phosphate (HA/β-TCP), calcium sulfate (CS), and polymethylmethacrylate (PMMA) bone cement are biomaterials clinically used to fill defective pedicles for pedicle screw augmentation. Few studies have systematically investigated the effects of various biomaterials utilized for salvage screw stabilization. The aim of this study was to evaluate the biomechanical properties of screws augmented with these four different materials and the effect of different pilot hole sizes and bone densities on screw fixation strength. Commercially available synthetic bones with three different densities (7.5 pcf, 15pcf, 30 pcf) simulating different degrees of bone density were utilized as substitutes for human bone. Two different pilot hole sizes (3.2 mm and 7.0 mm in diameter) were prepared on test blocks to simulate primary and revision pedicle screw fixation, respectively. Following separate specimen preparation with these four different filling biomaterials, a screw pullout test was conducted using a material test machine, and the average maximal screw pullout strength was compared among groups. The average maximal pullout strength of the materials, presented in descending order, was as follows: bone cement, calcium sulfate, HA/β-TCP, allograft bone chips and the control. In samples in both the 3.2 mm pilot-hole and 7.0 mm pilot-hole groups, the average maximal pullout strength of these four materials increased with increasing bone density. The average maximal pullout strength of the bone cement augmented salvage screw (7.0 mm) was apparently elevated in the 7.5 pcf test block. Salvage pedicle screw augmentation with allograft bone chips, HA/β-TCP, calcium sulfate, and bone cement are all feasible methods and can offer better pullout strength than materials in the non-augmentation group. Bone cement provides the most significantly augmented effect in each pilot hole size and bone density setting and could be considered preferentially to achieve larger initial stability during revision surgery, especially for bones with osteoporotic quality.

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.

C-reactive protein to albumin ratio (CAR) in predicting surgical site infection (SSI) following instrumented posterior lumbar interbody fusion (PLIF)

Identification of novel markers would contribute to the individualised risk assessment and development of a risk prediction model. This study aimed to investigate the role of the C-reactive protein to albumin ratio (CAR) in predicting surgical site infection (SSI) following instrumented posterior lumbar interbody fusion (PLIF) of lumbar degenerative diseases. This study enrolled patients who underwent PLIF and instrumentation for treatment of lumbar degenerative diseases between 2015 and 2020. Electronic medical records were inquired for data collection, with follow-up register for identifying SSI cases. The optimal cut-off for CAR was determined by constructing the receiver operator characteristic (ROC) curve. Patients with high- or low-CAR value were compared using the univariate analyses, and the association between CAR and the risk of SSI was investigated using multivariate logistics regression analysis. A total of 905 patients were enrolled, twenty-nine (3.2%) had developed an SSI with 72.4% occurring during index hospitalisation, and 11 (1.2%) had deep and 18 (2.0%) superficial SSIs. An SSI was associated with additional 10.7 days of index total hospital stay (P = .001). The CAR was 0-5.43 (median, 0.05), and the optimal cut-off was 0.09 and area under the curve was 0.720 (P < .001). 336 (37.1%) patients had a CAR ≥0.09 and 22 (6.5%) developed an SSI, with a crude risk of 5.6 relative to those with a low CAR. The multivariate analyses showed CAR ≥0.09 was associated with 8.06-fold increased risk of SSI, together with diabetes (P = .018), while hypertension was identified as a protective factor (OR, 0.34; 95%CI, 0.11-1.00, P = .049). High CAR is found to significantly predict the incident SSI following instrumented PLIF of lumbar degenerative diseases, and can be considered as a useful index in practice only after it is verified by future high-level evidences.

Vacuum-Assisted Wound Closure Management for Posterior Lumbar Spine Infections

A postoperative infection involving the tissues deep to the fascia is defined as a deep wound infection (DWI). Management of such infections after lumbar spinal surgery remains a challenge. One strategy is the use of vacuum-assisted wound closure (VAC) which applies negative pressure to the wound to improve microcirculation and to promote the formation of granulation tissue. When combined with antibiotics, VAC has been shown to successfully treat DWIs and is now a common strategy for treating deep postoperative wound infections after spinal surgery. In this article, we review the technique of VAC, its mechanism of action, indications and contraindications, and clinical outcomes in the treatment of DWIs after lumbar spinal surgery.

Treatment strategy for surgical site infection post posterior lumbar interbody fusion: A retrospective study

Introduction

Posterior lumbar interbody fusion (PLIF) has been widely used to treat various degenerative spinal diseases. However, surgical site infection (SSI) post-PLIF is often difficult to cure. This study aimed to clarify the difference in clinical course due to the causative organism and develop a treatment strategy for SSI post-PLIF.

Methods

Between January 2011 and March 2019, 581 PLIF surgeries were performed at our hospital. Deep SSI occurred in 14 patients who were followed up for more than 2 years. Causative bacterial species were diagnosed by preoperative puncture and/or intraoperative drainage or by tissue culture in 13 patients and by intradiscal puncture in one patient who underwent conservative treatment. Of the 13 patients who underwent surgeries for infection, 10 had Propionibacterium acnes (Group A; n = 4) or coagulase-negative Staphylococcus (CNS) (Group B; n = 6) as the causative bacterial species. Groups A and B were retrospectively compared in terms of age, sex, number of segments, presence of diabetes mellitus, operation time, blood loss, C-reactive protein on hematological examination, the elapsed time to diagnosis (ETD), the presence of clinical findings such as heat, redness, swelling, and discharge from the wound and healing time.

Results

All infections were eradicated with surgery except in one patient whose causative bacteria was CNS; cages were finally removed in 11 patients. There was a significant difference (P = 0.0105) in the ETD and clinical findings (P = 0.0476) between Groups A and B. Posterior one-stage simultaneous revision (POSSR) was performed in nine patients, of whom eight were cured and one required additional surgery.

Conclusions

The ETD and clinical findings were significantly different in SSI cases caused by different bacteria, which will be useful in predicting the causative bacteria in future cases. For the treatment of deep SSI post-PLIF, POSSR was effective.

Infections after spine instrumentation: effectiveness of short antibiotic treatment in a large multicentre cohort

BACKGROUND AND OBJECTIVES

Available information about infection after spine instrumentation (IASI) and its management are scarce. We aimed to analyse DAIR (debridement, antibiotics and implant retention) prognosis and evaluate effectiveness of short antibiotic courses on early forms.

METHODS

Multicentre retrospective study of patients with IASI managed surgically (January 2010-December 2016). Risk factors for failure were analysed by multivariate Cox regression and differences between short and long antibiotic treatment were evaluated with a propensity score-matched analysis.

RESULTS

Of the 411 IASI cases, 300 (73%) presented in the first month after surgery, 48 in the second month, 22 in the third and 41 thereafter. Infections within the first 2 months (early cases) occurred mainly to older patients, with local inflammatory signs and predominance of Enterobacteriaceae, unlike those in the later periods. When managed with DAIR, prognosis of early cases was better than later ones (failure rate 10.4% versus 26.1%, respectively; P = 0.02). Risk factors for DAIR failure in early cases were female sex, Charlson Score, large fusions (>6 levels) and polymicrobial infections (adjusted HRs of 2.4, 1.3, 2.6 and 2.26, respectively). Propensity score matching proved shorter courses of antibiotics (4-6 weeks) as effective as longer courses (failure rates 11.4% and 10.5%, respectively; P = 0.870).

CONCLUSIONS

IASIs within the first 2 months could be managed effectively with DAIR and shorter antibiotic courses. Clinicians should be cautious when faced with patients with comorbidities, large fusions and/or polymicrobial infections.

The comparison between anterior and posterior approaches for removal of infected lumbar interbody cages and a proposal regarding the use of endoscope-assisted technique

Background

In cases of postoperative deep wound infection after interbody fusion with cages, it is often difficult to decide whether to preserve or remove the cages, and there is no consensus on the optimal approach for removing cages. The aim of this study was to investigate the surgical management of cage infection after lumbar interbody fusion.

Methods

A retrospective study was conducted between January 2012 and August 2018. Patients were included if they had postoperative deep wound infection and required cage removal. Clinical outcomes, including operative parameters, visual analog scale, neurologic status, and fusion status, were assessed and compared between anterior and posterior approaches for cage removal.

Results

Of 130 patients who developed postoperative infection and required surgical debridement, 25 (27 levels) were diagnosed with cage infection. Twelve underwent an anterior approach, while 13 underwent cage removal with a posterior approach. Significant differences were observed between the anterior and posterior approaches in elapsed time to the diagnosis of cage infection, operative time, and hospital stay. All patients had better or stationary American Spinal Injury Association impairment scale, but one case of recurrence in adjacent disc 3 months after the surgery.

Conclusions

Both anterior and posterior approaches for cage removal, followed by interbody debridement and fusion with bone grafts, were feasible methods and offered promising results. An anterior approach often requires an additional extension of posterior instrumentation due to the high incidence of concurrent pedicle screw loosening. The use of an endoscope-assisted technique is suggested to facilitate safe removal of cages.

Surgical revision strategies for postoperative spinal implant infections (PSII)

Over the last years the number of spine surgeries with instrumentation has grown to an indispensable column in the treatment for different pathologies of the spine. A further increase in the incidence of instrumented spinal surgery is expected throughout the next years. Although the implementation and development of new techniques offer faster and more minimal invasive procedures, shortening surgery time, reducing soft tissue injury and revision due to hardware misplacement, the incidence of postoperative spinal implant infections (PSII) remains high. PSII related complications and revision procedures pose an enormous socioeconomic burden. Therefore, standardized strategies and protocols for treatment of PSII are urgently needed. While in former times hardware exchange or hardware removal was common practise in the field of spine surgery this approach has changed over the last years. Although the evidence from clinical studies in the field of PSII is of limited evidence, critical variables for revision strategies of PSII have been identified. Further, to quickly advance in the field of PSII it is certainly important to extrapolate and learn using data regarding the management from other fields of prosthetic joint infections. This should include clinical as well as experimental work in particular in the context of the biofilm, sonication as well as microbiological concepts. Over the last years, at our institution standardized procedures for diagnostic, surgical as well as antimicrobial treatment have been developed, based on the latest recommendations in peer-reviewed literature and our own data. Here we give an overview about surgical revision strategies for PSII and discuss the key points of our standardized protocol.

BMI Does Not Affect Complications or Patient Reported Outcomes After Lumbar Decompression Surgery

STUDY DESIGN

This is a retrospective comparative review.

OBJECTIVE

The objective of this study was to identify the influence of body mass index (BMI) on postsurgical complications and patient reported outcomes measures (PROMs) following lumbar decompression surgery.

SUMMARY OF BACKGROUND DATA

Current literature does not accurately identify the impact of BMI on postsurgical complications or outcomes.

MATERIALS AND METHODS

Records from a single-center, academic hospital were used to identify patients undergoing 1 to 3-level lumbar decompression surgery. Patients under 18 years of age, those undergoing surgery for infection, trauma, tumor, or revision, and those with <1-year follow-up were excluded. Patients were split into groups based on preoperative BMI: class I: BMI <25.0 kg/m; class II: BMI 25.0-29.9 kg/m; class III: BMI 30.0-34.9 kg/m; and class IV: BMI >35.0 kg/m. Absolute PROM scores, the recovery ratio and the percent of patients achieving minimum clinically important difference between groups were compared and a multiple linear regression analysis was performed.

RESULTS

A total of 195 patients were included with 34 (17.4%) patients in group I, 80 (41.0%) in group II, 49 (25.1%) in group III, and 32 (16.5%) in group IV. Average age was 60.0 (58.0, 62.0) years and average follow-up was 13.0 (12.6, 13.4) months. All patients improved significantly within each group, except for class III and class IV patients, who did not demonstrate significant improvements in terms of Mental Component Score (MCS-12) scores (P=0.546 and 0.702, respectively). There were no significant differences between BMI groups for baseline or postoperative PROM values, recovery ratio, or the percent of patients reaching minimum clinically important difference. Multiple linear regression analysis revealed that BMI was not a significant predictor for change in outcomes for any measure. The 30-day readmission rate was 6.2% and overall revision rate at final follow-up was 5.1%, with no significant differences between groups.

CONCLUSION

This study's results suggest that BMI may not significantly affect complications or patient outcomes at 1-year in those undergoing lumbar decompression surgery.

LEVEL OF EVIDENCE

Level III.

Implications for diagnosis and treatment of peri-spinal implant infections from experiences in periprosthetic joint infections-a literature comparison and review

Both, periprosthetic joint infection (PJI) and peri-spinal implant infection (PSII) are serious complications occurring in arthroplasty and spine instrumentation with absolute numbers expected to rise in the next years. The currently existing literature data describing the characteristics of PSII are limited when compared to PJI studies. However, both PJI and PSII exhibit similarities concerning pathogenesis, symptoms, diagnosis, treatment and prognosis. This literature review aims at comparing PJI and PSII and to develop implications for diagnosis and treatment of PSII from existing studies about PJI. The review was performed on the basis of a structured PubMed, Cochrane Library, and Medline analysis and existing guidelines, with 99 references being included. The results indicate that specific terms like re-infection should be defined in the context of PSII based on existing definitions of PJI, that in vitro biofilm studies and studies analyzing different prosthesis surfaces in arthroplasty could be used for PSII, and that histopathology as an additional standard tool in PSII diagnosis might be helpful. In addition, the development of a standardized algorithm-based treatment system with antibiotic protocols, including long term suppression, for PSII similar to the ones existing for PJI is necessary.

Revision Surgery for Postoperative Spondylodiscitis at Cage Level after Posterior Instrumented Fusion in the Lumbar Spine-Anterior Approach Is Not Absolutely Indicated

Spondylodiscitis at the cage level is rare but remains a challenge for spine surgeons. In this study, the safety and efficacy of revision surgery by a posterior approach to spondylodiscitis developed at the cage level were evaluated, and these data were compared to those of patients treated with revision surgeries using the traditional anterior plus posterior approach for their infections. Twenty-eight patients with postoperative spondylodiscitis underwent revision surgeries to salvage their infections, including 15 patients in the study group (posterior only) and 13 patients in the control group (combined anterior and posterior). Staphylococcus aureus was the most common pathogen in both groups. L4-L5 was the most common infection site in both groups. The operation time (229.5 vs. 449.5 min, p < 0.001) and blood loss (427.7 vs. 1106.9 mL, p < 0.001) were the only two data points that were statistically significantly different between the two groups. In conclusion, a single posterior approach with ipsilateral or contralateral transforaminal lumbar interbody debridement and fusion plus extending instrumentation was safe and effective for spondylodiscitis developed at the cage level. This strategy can decrease the operation time and blood loss.

Gas forming infection of the spine: a systematic and narrative review

PURPOSE

Gas forming infection (GFI) of the spine is a rapidly progressive and potentially life-threatening infection. It can be a consequence of aetiologies such as Emphysematous Osteomyelitis (EOM), Necrotizing Fasciitis (NF), and Gas-containing Spinal Epidural Abscess (Gas-containing SEA). This review aims to summarize the characteristics of these subtypes of GFI, describing their aetiology, diagnosis, management, and prognosis.

METHODS

PubMed, Embase, Web of Science and the Cochrane Database were systematically searched for studies reporting on gas forming infections of the spine or a known subtype. Cases of post-operative and iatrogenic spinal infection were excluded.

RESULTS

The literature review revealed 35 studies reporting on 28 cases of EOM, three cases of NF involving the spine and seven cases of Gas-containing SEA. Thirty studies reporting on 32 cases of GFI were available for data analysis. The mean age of the patients was 60.9 years and a concomitant diagnosis of diabetes mellitus was reported in 57.5% of patients infected. Fever and back pain were the most common presenting symptoms. The lumbar spine was the most commonly affected spinal segment. Mortality from EOM, NF and Gas-containing SEA were 34.8, 100 and 28.5%, respectively.

DISCUSSION

Gas forming infection of the spine is a rare condition with an extremely poor prognosis, requiring early and aggressive surgical treatment. A multi-disciplinary approach is necessary for management. Nonetheless, even in cases of early recognition and optimal management, multisystem failure may still occur, and mortality rates remain high due to the aggressive nature of this infection.

LEVEL OF EVIDENCE

Systematic review of level IV studies.

Outcome of spinal implant-associated infections treated with or without biofilm-active antibiotics: results from a 10-year cohort study

Purpose

Biofilm-active antibiotics are suggested to improve the outcome of implant-associated infections; however, their role in infections after spinal instrumentation is unclear. Therefore, we evaluated the outcome of patients with spinal implant-associated infections treated with and without biofilm-active antibiotics.

Methods

The probability of infection-free survival was estimated for treatment of spinal implant-associated infections with and without biofilm-active antibiotics using the Kaplan–Meier method; Cox proportional-hazards regression model was used to identify factors associated with treatment failure.

Results

Among 93 included patients, early-onset infection was diagnosed in 61 (66%) and late-onset in 32 infections (34%). Thirty patients (32%) were treated with biofilm-active antibiotic therapy and 63 (68%) without it. The infection-free survival after a median follow-up of 53.7 months (range, 8 days-9.4 years) was 67% (95% confidence interval [CI], 55–82%) after 1 year and 58% (95% CI 43–71%) after 2 years. The infection-free survival after 1 and 2 years was 94% (95% CI 85–99%) and 84% (95% CI 71–93%) for patients treated with biofilm-active antibiotics, respectively, and 57% (95% CI 39–80%) and 49% (95% CI 28–61%) for those treated without biofilm-active antibiotics, respectively (p = 0.009). Treatment with biofilm-active antibiotics (hazard ratio [HR], 0.23, 95% CI 0.07–0.77), infection with Staphylococcus auras (HR, 2.19, 95% CI 1.04–4.62) and polymicrobial infection (HR, 2.44, 95% CI 1.09–6.04) were significantly associated with treatment outcome. Severe pain was observed more often in patients without biofilm-active antibiotic therapy (49% vs. 18%, p = 0.027).

Conclusion

Treatment with biofilm-active antibiotics was associated with better treatment outcome and less postoperative pain intensity.

Electronic supplementary material

The online version of this article (10.1007/s15010-020-01435-2) contains supplementary material, which is available to authorized users.

Consensus on Implants in Infections After Spine Surgery

In July of 2018, the Second International Consensus Meeting (ICM) on Musculoskeletal Infection convened in Philadelphia, PA was held to discuss issues regarding infection in orthopedic patients and to provide consensus recommendations on these issues to practicing orthopedic surgeons. During this meeting, attending delegates divided into subspecialty groups to discuss topics specifics to their respective fields, which included the spine. At the spine subspecialty group meeting, delegates discussed and voted upon the recommendations for 63 questions regarding the prevention, diagnosis, and treatment of infection in spinal surgery. Of the 63 questions, 9 focused on implants questions in spine surgery, for which this article provides the recommendations, voting results, and rationales.

Consensus on the Role of Antibiotic Use in SSI Following Spinal Surgery

In July of 2018, the Second International Consensus Meeting (ICM) on Musculoskeletal Infection convened in Philadelphia, PA was held to discuss issues regarding infection in orthopedic patients and to provide consensus recommendations on these issues to practicing orthopedic surgeons. During this meeting, attending delegates divided into subspecialty groups to discuss topics specifics to their respective fields, which included the spine. At the spine subspecialty group meeting, delegates discussed and voted upon the recommendations for 63 questions regarding the prevention, diagnosis, and treatment of infection in spinal surgery. Of the 63 questions, 17 focused on the use of antibiotics in spine surgery, for which this article provides the recommendations, voting results, and rationales.

Classification and Management Algorithm for Postoperative Wound Complications Following Transforaminal Lumbar Interbody Fusion

Study Design

Retrospective study.

Purpose

Postoperative wound complications occurring after transforaminal lumbar interbody fusion (TLIF) are unique, as they can involve different tissue zones (subcutaneous, subfascial, osseous, peri-implant, and disc).

Overview of Literature

Management of postoperative infections occurring after TLIF remains controversial in the context of retention or removal of implants.

Methods

A total of 1,279 consecutive patients (1,520 segments) who underwent TLIF with a minimum follow-up of 1 year were analyzed. Patients with wound complications were classified anatomically into the following five types: type 1, suprafascial necrosis; type 2, wound dehiscence; type 3, pus around screws and rods; type 4, bone marrow edema; and type 5, pus in the disc space. Details pertaining to clinicoradiological and laboratory findings and management were also recorded.

Results

Of the 62 patients (4.8%) with wound complications, there were seven patients in type 1, 35 in type 2, 10 in type 3, four in type 4, and six in type 5. Patients in types 1 and 2 manifested delayed wound healing and were systemically well. In type 1, five patients were managed with resuturing and two were managed conservatively. In type 2, all patients had wound gaping and were managed by debridement, whereas three patients required vacuum-assisted closure. Patients in type 3 had severe back pain and fever, with demonstrable pus around the screw site. Tissue culture identified organisms in 90% of the patients. Patients in type 4 presented with increasing back pain, and magnetic resonance imaging revealed vertebral bone marrow edema. Those in type 5 had severe back pain and fever, with demonstrable pus in the disc space. Patients in types 3–5 required debridement, implant revision/retention, and long-term antibiotics.

Conclusions

The new anatomical classification of surgical site infections could help grade the severity of infection and provide tangible treatment guidelines, resulting in better infection clearance and patient outcomes.

Infection with Spinal Instrumentation: A 20-Year, Single-Institution Experience with Review of Pathogenesis, Diagnosis, Prevention, and Management

Objective and Importance

Instrumentation has become an integral component in the management of various spinal pathologies. The rate of infection varies from 2% to 20% of all instrumented spinal procedures. Postoperative spinal implant infection places patients at risk for pseudo-arthrosis, correction loss, spondylodiscitis, and adverse neurological sequelae and increases health-care costs.

Materials and Methods

We performed a cohort study of 1065 patients who underwent instrumented spinal procedures in our institution between 1995 and 2014. Fifty-one patients (4.79%) contracted postoperative spinal infection. Isolated bacterial species, infection severity, diagnosis/treatment timing, surgical/medical strategy treatment, and patient's medical background were evaluated to assess their relationship with management outcome.

Results

Multiple risk factors for postoperative spinal infection were identified. Infections may be early or delayed. C-reactive protein and magnetic resonance imaging are important diagnostic tools. Prompt diagnosis and aggressive therapy (debridement and parenteral antibiotics) were responsible for implant preservation in 49 of 51 cases, whereas implant removal noted in two cases was attributed to delayed treatment and uncontrolled infection with implant loosening or late infection with spondylodesis. Infection in the setting of instrumentation is more difficult to diagnose and treat due to biofilm.

Conclusion

Retention of the mechanically sound implants in early-onset infection permits fusion to occur, whereas delayed treatment and multiple comorbidities will most likely result in a lack of effectiveness in eradicating the infecting pathogens. An improved understanding of the role of biofilm and the development of newer spinal implants has provided insight into the pathogenesis and management of infected spinal implants. It is important to accurately identify and treat postoperative spinal infections. The treatment is multimodal and prolonged.

Surgical Site Infection as a Risk Factor for Long-Term Instrumentation Failure in Patients with Spinal Deformity: A Retrospective Cohort Study

BACKGROUND

Surgical site infection (SSI) remains a complication of spine deformity surgery. Although fusion/instrumentation failure in the setting of SSI has been reported, few studies have investigated the relationship between these entities. We examine the relationship between early SSI and fusion/instrumentation failure after instrumented fusion in patients with thoracolumbar scoliosis.

METHODS

A retrospective review of a prospectively maintained case series for patients undergoing spine surgery between January 1, 2006, and October 3, 2017. Inclusion criteria included age ≥18 years and surgery performed for correction of thoracolumbar scoliosis. Data collected included various demographic, clinical, and operative variables.

RESULTS

532 patients met inclusion criteria, with 20 (4%) experiencing SSI. Diabetes mellitus was the only demographic risk factor for increased SSI (P = 0.026). Number of fused levels, blood volume loss, and operative time were similar between groups. Fusion/instrumentation failure occurred in 68 (13%) patients, 10 of whom (15%) had SSI, whereas of the 464 patients with no fusion/instrumentation failure, only 10 (2%) had SSI (P < 0.001). Of the 20 patients with SSI, 10 (50%) had fusion/instrumentation failure, whereas in the 512 patients with no infection, only 58 (11%) had fusion/instrumentation failure (P < 0.001). Patients with infection also experienced significantly shorter time to fusion/instrumentation failure (P = 0.025), higher need for revision surgery (P < 0.001), and shorter time to revision surgery (P = 0.012).

CONCLUSIONS

Early SSI significantly increases the risk of fusion/instrumentation failure in patients with thoracolumbar scoliotic deformity, and it significantly shortens the time to failure. Patients with early SSI have a significantly higher likelihood of requiring revision surgery and after a significantly shorter time interval.

Comparison of pyogenic postoperative and native vertebral osteomyelitis

BACKGROUND CONTEXT

Postoperative vertebral osteomyelitis (PVO) after spinal surgery is a clinical challenge. However, there is a paucity of evidence regarding the most likely etiologic organisms to guide the choice of empirical antibiotic therapy, and previous reports of treatment outcomes for PVO are scarce.

PURPOSE

To compare the microbiology, clinical characteristics, and outcomes of pyogenic PVO with native vertebral osteomyelitis (NVO).

STUDY DESIGN

Retrospective comparative study.

PATIENT SAMPLE

Patients with microbiologically proven vertebral osteomyelitis from three university-affiliated hospitals in South Korea between January 2005 and December 2015 with follow-up of at least 12 months after completion of antibiotics or until the patient was transferred. Patients who had a spine operation in the same location within 1 year of diagnosis, and all patients with remnant implants at the time of the vertebral osteomyelitis diagnosis, were defined as having PVO. The remainder of the patients was considered to have NVO. Spinal operations included discectomy, laminectomy, arthrodesis, and instrumentation for stabilization of the spine.

OUTCOME MEASURES

Overall mortality, neurologic outcomes, treatment failure, and relapse of infection.

METHODS

Demographic data, comorbidities, presenting symptoms, microbiological data, radiographic characteristics, laboratory data (including white blood cell counts, erythrocyte sedimentation rate, and C-reactive protein), surgical treatment, and neurologic outcomes for each patient were reviewed from electronic medical records and analyzed. Mortality rate, treatment failure, and relapse of infection were calculated for the two groups. Factors associated with treatment outcome were evaluated using univariate and multivariate logistic regression analyses.

RESULTS

The study evaluated 104 patients with PVO and 441 patients with NVO. In PVO, the most common isolate was Staphylococcus aureus (34%, n=35), followed by coagulase-negative staphylococci (31%, n=32). In NVO, the most common isolates were S. aureus (47%, n=206) and streptococci (21%, n=94). Of the staphylococci, the proportion of methicillin-resistant strains was significantly higher in PVO than that in NVO (75% vs. 39%, p<.001). The proportion of patients with gram-negative bacilli was 14% in PVO and 20% in NVO. Pre-existing or synchronous nonspinal infection was observed more frequently in NVO than in PVO (33% vs. 13%, p<.001). Although the duration of antibiotic use was similar in both groups, surgery for infection control was performed more frequently in PVO. The mortality rate was similar in both groups. However, the treatment failure and relapse rates at 12 months were higher in the PVO group (23% vs. 13%, p=.009; 14% vs. 7%, p=.028, respectively). Methicillin-resistant S.aureus was significantly associated with treatment failure or relapse via logistic regression (odds ratio 3.01, 95% confidence interval [1.71-5.32], p<.001; odds ratio 2.78, 95% confidence interval [1.40-5.49], p=.003).

CONCLUSIONS

Coverage of methicillin-resistant staphylococci should be considered when prescribing empirical antibiotics for PVO. Although surgery was performed more often in PVO than NVO, the treatment failure and relapse rates at 12 months were higher in PVO.

Management of Infected Transforaminal Lumbar Interbody Fusion Cage in Posterior Degenerative Lumbar Spine Surgery

BACKGROUND

The postoperative infection rates for transforaminal lumbar interbody fusion (TLIF) have ranged from <2% to 4%. However, no consensus has been reached on the treatment strategies. TLIF cage preservation or revision surgery for lumbar spine reconstruction are 2 possible treatments. We aimed to determine the most effective method for organ/space infection control.

METHODS

The data from 4923 patients who had undergone TLIF with cage and posterior pedicle-screw instrumentation for spondylolysis or degenerative spondylolisthesis from January 2008 to December 2015 were retrospectively analyzed. Of the 4923 patients, 32 (0.65%) had developed organ/space infection of the interbody cage and were divided into 2 groups: those whose interbody cage was removed for revision (group 1) and those who interbody cage was retained (group 2). We compared the initial management of both groups in terms of age, sex, elapsed time to diagnosis, changes in spinal lordotic angle, visual analog scale score, fusion status, and Kirkaldy-Willis functional outcomes.

RESULTS

The 32 patients with organ/space infection had a mean age of 66.3 years and a follow-up period of 23.8 months. Significant differences were observed in the mean elapsed time to diagnosis (P = 0.004), lordotic angle correction at the disease level (P = 0.03), and Kirkaldy-Wallis functional outcomes (P = 0.01). Of the 17 patients undergoing debridement for implant retention, 9 (52.9%) exhibited poor results.

CONCLUSIONS

The most important factor contributing to TLIF cage retention failure was epidural fibrosis of the previous transforaminal route and biofilm adhesion on interbody devices affecting infection clearance. Thus, we would recommend a combined anterior and posterior approach or the transforaminal route for radical debridement with cage removal and fusion to achieve better clinical outcomes.

Postoperative Infection in Patients Undergoing Posterior Lumbosacral Spinal Surgery: A Pictorial Guide for Diagnosis and Early Treatment

Surgical site infections after posterior spinal surgery may lead to spondylodiscitis, pseudarthrosis, correction loss, adverse neurological sequelae, sepsis, and poor outcomes if not treated immediately. Infection rates vary depending on the type and extent of operative procedures, use of instrumentation, and patients' risk factors. Image evaluation is crucial for early diagnosis and should be complementary to clinical routes, laboratory survey, and treatment timing. Magnetic resonance imaging detects early inflammatory infiltration into the vertebrae and soft tissues, including hyperemic changes of edematous marrow, vertebral endplate, and abscess or phlegmon accumulation around the intervertebral disk, epidural, and paravertebral spaces. Aggressive surgical treatment can eradicate infection sources, obtain a stable wound closure, decrease morbidity, and restore spinal integrity. Organ/space infection is defined as any body parts opened to manipulate other than superficial/deep incision. Advanced magnetic resonance imaging evaluating abnormal fluid accumulation, heterogenous contrast enhancement of the endplate erosion due to cage/screw infection is categorized to inform a presumptive diagnosis for early implant salvage. However, patients' defense response, infection severity, bacteriology, treatment timing, spinal stability, and available medical and surgical options must be fully considered. Revision surgery is indicated for pseudarthrosis, implant loosening with correction loss, recalcitrant spondylodiscitis, and adjacent segment diseases for infection control.

Incidence and risk factors of wound complications in long segment instrumented thoracolumbar spinal fusions: a retrospective study

BACKGROUND

This is a retrospective analysis of prospectively collected data. Our objective was to determine the incidence and assess the risk factors associated with surgical site wound complications in long segment (7+ vertebrae) instrumented thoracolumbar fusions. Surgical site complications lead to patient morbidity, increased financial burden, and further medical intervention. Risk factors for wound complications in spinal surgery include patient factors such as obesity and diabetes, and surgical factors such as operative time and procedure type. Fusion with instrumentation is one of the strongest associated risk factors in the literature.

METHODS

A comprehensive search of the National Surgical Quality Improvement Program (NSQIP) from 2005 to 2014 was performed, selecting cases based on Current Procedural Terminology (CPT) codes. Cases were then stratified based on the presence of one of the following wound complications: superficial surgical site infection, deep surgical site infection, organ space infection, and wound dehiscence. Univariate and bivariate analyses were performed to determine risk factors.

RESULTS

A total of 2,548 cases were identified, and the most common diagnoses were scoliosis (29%), spondylosis (17%) and spinal stenosis (14%). Overall, 4.24% of cases had at least one wound complication. Identified risk factors include obesity, preoperative transfusion, preoperative wound infection, and operative time. Associated outcomes include stroke with neurological deficit, perioperative transfusion, deep vein thrombosis (DVT), sepsis, septic shock, readmission, reoperation, and longer length of hospital stay. Many of these variables are independently associated with a wound complication.

CONCLUSIONS

Our analysis of the NSQIP demonstrated risk factors and complications associated with wound infections in the setting of long segment fusions (7+ levels). These findings may aid surgeons in determining a patient's risk of developing a wound complication, with the goal of lessening the associated morbidity and economic burden.

Perioperative Medical Complications after Posterior Approach Spinal Instrumentation Surgery for Osteoporotic Vertebral Collapse: A Comparative Study in Patients with Primary Osteoporosis and Those with Secondary Osteoporosis

Study Design

A retrospective comparative study.

Purpose

To compare perioperative medical complications after posterior approach spinal instrumentation surgery for osteoporotic vertebral collapse (OVC) between patients with primary osteoporosis and those with secondary osteoporosis.

Overview of Literature

With increased aging of society, the demand for instrumentation surgery for an osteoporotic spine has been increasing. However, no studies have compared the rates or severities of perioperative complications after spinal instrumentation surgery between patients with primary osteoporosis and those with secondary osteoporosis.

Methods

Ninety-one patients with OVC aged ≥50 years (23 males and 68 females) who underwent posterior approach vertebral replacement with cages or posterior spinal fusion combined with vertebroplasty were divided into primary (n=56) and secondary (n=35) osteoporosis groups. Bone mineral density (BMD), osteoporosis treatment prior to OVC, operative invasiveness, and perioperative medical complications were compared.

Results

Diabetes mellitus (51.4%) was the most common cause of secondary osteoporosis, followed by glucocorticoid use (22.9%). No significant differences were seen in terms of age, gender, BMD, osteoporosis treatment, or operative invasiveness, including the number of levels fused, estimated blood loss, and number of patients requiring transfusion. No significant difference in the incidence of perioperative complications were observed between the primary and secondary osteoporosis groups (16.1% vs. 22.9%). However, surgical site infection (SSI) was significantly more frequently seen in the secondary osteoporosis group (11.4%) than in the primary osteoporosis group (1.8%; p<0.05). One patient in the secondary osteoporosis group developed methicillin-resistant Staphylococcus aureus infection that ultimately required instrument removal.

Conclusions

The overall incidence of perioperative medical complications after posterior approach spinal instrumentation surgery for OVC was comparable between the primary and secondary osteoporosis groups under conditions of similar background characteristics and operative invasiveness. However, SSI (particularly more severe cases) occurred more frequently in patients with secondary osteoporosis.

MRI-based Decision Making of Implant Removal in Deep Wound Infection After Instrumented Lumbar Fusion

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of the study was to review the treatment of deep wound infection after posterior instrumented lumbar fusion, and thereby to optimize the decision-making process of implant removal or retention on the basis of magnetic resonance imaging (MRI) assessment.

SUMMARY OF BACKGROUND DATA

Biofilm formed on the surface of the spinal implant prevents infiltration of antibiotics and makes the infection treatment more complicated. The decision of implant removal, if necessary, should be made appropriately, but the problem is a lack of consensus for implant removal or retention.

METHODS

A total of 1445 consecutive patients who underwent posterior instrumented lumbar fusion were reviewed retrospectively. There were 23 deep wound infections (1.6%) requiring surgical treatment. MR images were used to evaluate the presence or absence of osteomyelitis of the instrumented vertebra and intervertebral abscess.

RESULTS

Six patients in the negative MRI group (n=7) were successfully treated by a single salvage surgery without implant removal; fusion occurred in 86% of the patients. However, in the positive MRI group (n=13), 4 patients required implant removal at the initial surgery and 5 patients eventually warranted implant removal after an average of 2.4 additional operations. Notably, 3 of the 4 patients who kept the implants ended up with a loss of fixation stability attributed to screw loosening with a progressive destruction of the instrumented vertebra. Therefore, the fusion rate was only 23% for the MRI-positive patients. Furthermore, making a wrong decision regarding implant removal increased the number of salvage surgeries and frequently resulted in progressive bone destruction and pseudarthrosis.

CONCLUSIONS

Once vertebral osteomyelitis and/or intervertebral abscess were evident in MR images, all the hardware should be removed. Failure to adhere to this recommendation resulted in multiple additional failed operations, and ultimately pseudarthrosis with further bony destruction.

Does Minimally Invasive Spine Surgery Minimize Surgical Site Infections?

STUDY DESIGN

Retrospective review of prospectively collected data.

PURPOSE

To evaluate the incidence of surgical site infections (SSIs) in minimally invasive spine surgery (MISS) in a cohort of patients and compare with available historical data on SSI in open spinal surgery cohorts, and to evaluate additional direct costs incurred due to SSI.

OVERVIEW OF LITERATURE

SSI can lead to prolonged antibiotic therapy, extended hospitalization, repeated operations, and implant removal. Small incisions and minimal dissection intrinsic to MISS may minimize the risk of postoperative infections. However, there is a dearth of literature on infections after MISS and their additional direct financial implications.

METHODS

All patients from January 2007 to January 2015 undergoing posterior spinal surgery with tubular retractor system and microscope in our institution were included. The procedures performed included tubular discectomies, tubular decompressions for spinal stenosis and minimal invasive transforaminal lumbar interbody fusion (TLIF). The incidence of postoperative SSI was calculated and compared to the range of cited SSI rates from published studies. Direct costs were calculated from medical billing for index cases and for patients with SSI.

RESULTS

A total of 1,043 patients underwent 763 noninstrumented surgeries (discectomies, decompressions) and 280 instrumented (TLIF) procedures. The mean age was 52.2 years with male:female ratio of 1.08:1. Three infections were encountered with fusion surgeries (mean detection time, 7 days). All three required wound wash and debridement with one patient requiring unilateral implant removal. Additional direct cost due to infection was $2,678 per 100 MISS-TLIF. SSI increased hospital expenditure per patient 1.5-fold after instrumented MISS.

CONCLUSIONS

Overall infection rate after MISS was 0.29%, with SSI rate of 0% in non-instrumented MISS and 1.07% with instrumented MISS. MISS can markedly reduce the SSI rate and can be an effective tool to minimize hospital costs.

Mediating bone regeneration by means of drug eluting implants: From passive to smart strategies

In addition to excellent biocompatibility and mechanical performance, the new generation of bone and craniofacial implants are expected to proactively contribute to the regeneration process and dynamically interact with the host tissue. To this end, integration and sustained delivery of therapeutic agents has become a rapidly expanding area. The incorporated active molecules can offer supplementary features including promoting oteoconduction and angiogenesis, impeding bacterial infection and modulating host body reaction. Major limitations of the current practices consist of low drug stability overtime, poor control of release profile and kinetics as well as complexity of finding clinically appropriate drug dosage. In consideration of the multifaceted cascade of bone regeneration process, this research is moving towards dual/multiple drug delivery, where precise control on simultaneous or sequential delivery, considering the possible synergetic interaction of the incorporated bioactive factors is of utmost importance. Herein, recent advancements in fabrication of synthetic load bearing implants equipped with various drug delivery systems are reviewed. Smart drug delivery solutions, newly developed to provide higher tempo-spatial control on the delivery of the pharmaceutical agents for targeted and stimuli responsive delivery are highlighted. The future trend of implants with bone drug delivery mechanisms and the most common challenges hindering commercialization and the bench to bedside progress of the developed technologies are covered.

Treatment of Surgical Site Infection in Posterior Lumbar Interbody Fusion

STUDY DESIGN

A retrospective observational and case control study.

PURPOSE

To identify appropriate treatment options according to the types of surgical site infections (SSI) in instrumented posterior lumbar interbody fusion (PLIF).

OVERVIEW OF LITERATURE

There has been no agreement or consensus with regard to this matter.

METHODS

Thirty-two consecutive SSIs were included and followed for more than one year. The elapsed time to diagnosis (ETD) according to the type of SSI was analyzed. The treatment options for each type and consequent clinical results were reviewed. The risk factors of removing the implants were analyzed.

RESULTS

There were 6/32 (19%) superficial incisional, 6/32 (19%) deep incisional, and 20/32 (62%) organ/space infection cases (SII, DII, and O/SI, respectively) (p=0.002). ETD was 8.5±2.3 days in SII, 8.7±2.3 days in DII, and 164.5±131.1 days in O/SI (p=0.013). All cases of SII and DII retained implants and were treated by repeated irrigation and secondary closure. Among O/SIs, 10/20 were treated conservatively. Nine out of ten underwent posterior one stage simultaneous revision (POSSR) and in one case, the cage was removed anteriorly. Those who had ETDs longer than 3 months showed a significant risk of implant removal (p=0.008, odds ratio [OR]=40.3). The Oswestry disability index (ODI) improved from 47.3% to 33.8% in SII, from 55.0% to 32.3% in DII, and from 53.4% to 42.1% in O/SI (p=0.002). There was no difference among the three groups (p=0.106); however, there was a partial correlation between ETD and final ODI (r=0.382, p=0.034).

CONCLUSIONS

Latent O/SI was the most common type of SSI in PLIF. In cases of SII and DII, early aggressive wound management and secondary closure was effective and implant removal was not necessary. In some cases of O/SI, implant removal was unavoidable. However, implant removal could be averted by an earlier diagnosis. POSSR was feasible and safe. Functional outcomes were improved; however, disability increased as ETD increased.

Efficiency of Hyperbaric Oxygen Therapy in Iatrogenic Spinal Infections

STUDY DESIGN

Retrospective clinical study.

OBJECTIVE

The aim of this study is to reveal the effectiveness of HBO therapy in iatrogenic spinal infections intractable to antibiotic therapy alone.

SUMMARY OF BACKGROUND DATA

The efficiency of hyperbaric oxygen (HBO) therapy, which is currently being used in many areas, has been proven in infections in deep and superficial locations and in osteomyelitis. The aim of this study is to reveal effectives of HBO therapy in iatrogenic spinal infections intractable to antibiotic alone therapy.

METHODS

HBO therapy was given to 19 cases of iatrogenic spinal infection between 2008 and 2013. Adjuvant HBO therapy was applied to cases that had exhibited no improvement in clinical and laboratory findings despite medical treatment for at least 3 weeks. Several parameters including demographic characteristics, surgical area, etiology and the surgical treatment modality, microbiology (culture material and causative organism), clinical and laboratory results, duration of HBO therapy, and outcome were reviewed.

RESULTS

The mean age was 54.6 years (range: 32-75 years). Iatrogenic spinal infections were most frequent in the lumbar region. It occurred after spine instrumentation in 12 cases and after micro-discectomy in 7 cases. The average number of HBO therapy sessions applied was 20.1 (range: 10-40). Wound discharge and clinical and laboratory findings recovered in all cases at the end of the therapy course. No revision or removal of the instrumentation was necessary in the instrumented cases.

CONCLUSION

HBO therapy is a treatment modality, which is safe and efficient as an adjuvant therapy in the treatment of infections. It was also seen to be effective in the prevention of revision procedures and instrumentation failures in iatrogenic osteomyelitis cases, which had occurred following spinal instrumentation.

LEVEL OF EVIDENCE

4.

Particular Features of Surgical Site Infection in Posterior Lumbar Interbody Fusion

BACKGROUND

Previous reports have observed differences only in infection rates between posterolateral fusion and posterior lumbar interbody fusion (PLIF). There have been no reports that describe the particular features of surgical site infection (SSI) in PLIF. In this study, we endeavor to identify the distinguishing characteristics and risk factors of SSI in PLIF.

METHODS

Our study undertook a review of a case series of an institute. Patients who had undergone PLIF consecutively in the author's hospital were reviewed. Two proactive procedures were introduced during the study period. One was irrigation of the autolocal bone, and the other was the intradiscal space irrigation with a nozzle. Infection rate and risk factors were analyzed. For subgroup analysis, the elapsed time to a diagnosis (ETD), clinical manifestations, hematologic findings, and causative bacteria were examined in patients with SSI.

RESULTS

In a total of 1,831 cases, there were 30 cases of SSI (1.6%). Long operation time was an independent risk factor (p = 0.008), and local bone irrigation was an independent protective factor (p = 0.001). Two cases of referred SSI were included in the subgroup analysis. There were 6/32 (19%) superficial incisional infections (SII), 6/32 (19%) deep incisional infections (DII), and 20/32 (62%) organ/space infections (O/SI). The difference of incidence among three groups was significant (p = 0.002).The most common bacteria encountered were methicillin-resistant Staphylococcus epidermidis followed by methicillin-resistant S. aureus in incisional infections, and no growth followed by S. epidermidis in O/SI. ETD was 8.5 ± 2.3 days in SII, 8.7 ± 2.3 days in DII and 164.5 ± 131.1 days in O/SI (p = 0.013).

CONCLUSIONS

The rate of SSI in PLIF was 1.6%, with the most common type being O/SI. The causative bacteria of O/SI was of lower virulence than in the incisional infection, and thus diagnosis was delayed due to its latent and insidious feature. Contamination of auto-local bone was presumed attributable to the progression of SSI. Irrigation of auto-local bone helped in the reduction of SSI.

Continuous irrigation and drainage for early postoperative deep wound infection after posterior instrumented spinal fusion

STUDY DESIGN

A retrospective study of clinical cases.

PURPOSE

To evaluate the efficacy of continuous irrigation and drainage for early postoperative deep wound infection after posterior instrumented spinal fusion.

SUMMARY OF BACKGROUND DATA

Aggressive debridement and irrigation has been recommended to treat postoperative wound infections after instrumented spinal fusion. However, this method of management, indicating repeating visits to the operating room until the wound is clean enough for closure, often results in prolonged hospitalization, increased cost, and sometimes compromise of the desired outcome. We hypothesize that repeat visits to the operating room for debridements can be avoided by aggressive debridements and primary closure with continuous irrigation and drainage for postoperative wound infections.

METHODS

From 2004 to 2009, 23 patients with early postoperative deep wound infections after spinal fusion with instrumentation were surgically treated with thorough debridement and primary closure with continuous irrigation and drainage. All patients were followed up for 30.6 months (range, 24-54 mo).

RESULTS

The mean duration of irrigation was 12.0 days (range, 7-16 d). In 21 patients (91.3%), the wound healed after continuous irrigation. The removal of the instrumentation or cages was not required in any case. Spinal fusion was achieved in all cases, except 1, where the patient developed a pseudoarthrosis at the L4-L5 level after L4-S1 fusion. The mean ODI for these 23 patients improved significantly from 53.4±18.7 preoperatively to 18.3±11.2 at the final follow-up visit (P<0.001). The mean JOA scores increased significantly from 15.5±4.1 preoperatively to 24.3±3.8 at the final follow-up (P<0.001).

CONCLUSIONS

Continuous irrigation and drainage is an effective and safe method for the treatment of early postoperative deep wound infection after posterior instrumented spinal fusion.

Management of wound infection after lumbar arthrodesis maintaining the instrumentation

<sec><title>OBJECTIVE:</title><p> To determinate whether a surgical protocol with immediate extensive debridement, closed irrigation system and antibiotic therapy would be effective to achieve healing of deep wound infection without removing the instrumentation.</p></sec><sec><title>METHODS:</title><p> Prospective cohort study with 19 patients presenting degenerative spinal stenosis or degenerative spondylolisthesis, who developed infection after posterior lumbar arthrodesis. The diagnosis was confirmed by a microbial culture from subfascial lumbar fluid and/or blood. Patients were treated with a protocol of wound exploration, extensive flushing and debridement, placement of a closed irrigation system that was maintained for five days and intravenous antibiotics. The instrumentation system was not removed.</p></sec><sec><title>RESULTS:</title><p> Mean age was 59.31 (±13.17) years old and most patients were female (94.7%; 18/19). The mean period for the identification of the infection was 2 weeks and 57.9% underwent a single wound exploration. White blood count, erythrocyte sedimentation rate and C-reactive protein showed a significant decrease post-treatment when compared to pre-treatment values. A significant reduction of erythrocyte sedimentation rate and C-reactive protein was also observed at the final evaluation. No laboratory test was useful to predict the need for more than one debridement.</p></sec><sec><title>CONCLUSION:</title><p> Patients with wound infection after instrumentation can be treated without removal of the instrumentation through wound exploration, extensive flushing, debridement of necrotic tissue, closed irrigation system during 5 days and proper antibiotic therapy. The blood tests were not useful to predict surgical re-interventions.</p></sec>

Surgical site infections following spine surgery: eliminating the controversies in the diagnosis

Surgical site infection (SSI) following spine surgery is a dreaded complication with significant morbidity and economic burden. SSIs following spine surgery can be superficial, characterized by obvious wound drainage or deep-seated with a healed wound. Staphylococcus aureus remains the principal causal agent. There are certain pre-operative risk factors that increase the risk of SSI, mainly diabetes, smoking, steroids, and peri-operative transfusions. Additionally, intra-operative risk factors include surgical invasiveness, type of fusion, implant use, and traditional instead of minimally invasive approach. A high level of suspicion is crucial to attaining an early definitive diagnosis and initiating appropriate management. The most common presenting symptom is back pain, usually manifesting 2–4 weeks and up to 3 months after a spinal procedure. Scheduling a follow-up visit between weeks 2 and 4 after surgery is therefore necessary for early detection. Inflammatory markers are important diagnostic tools, and comparing pre-operative with post-operative levels should be done when suspecting SSIs following spine surgery. Particularly, serum amyloid A is a novel inflammatory marker that can expedite the diagnosis of SSIs. Magnetic resonance imaging remains the diagnostic modality of choice when suspecting a SSI following spine surgery. While 18F-fluorodeoxyglucose-positron emission tomography is not widely used, it may be useful in challenging cases. Despite their low yield, blood cultures should be collected before initiating antibiotic therapy. Samples from wound drainage should be sent for Gram stain and cultures. When there is a high clinical suspicion of SSI and in the absence of superficial wound drainage, computed tomography-guided aspiration of paraspinal collections is warranted. Unless the patient is hemodynamically compromised, antibiotics should be deferred until proper specimens for culture are secured.

Infection with spinal instrumentation: Review of pathogenesis, diagnosis, prevention, and management

Background:

Instrumentation has become an integral component in the management of various spinal pathologies. The rate of infection varies from 2% to 20% of all instrumented spinal procedures. Every occurrence produces patient morbidity, which may adversely affect long-term outcome and increases health care costs.

Methods:

A comprehensive review of the literature from 1990 to 2012 was performed utilizing PubMed and several key words: Infection, spine, instrumentation, implant, management, and biofilms. Articles that provided a current review of the pathogenesis, diagnosis, prevention, and management of instrumented spinal infections over the years were reviewed.

Results:

There are multiple risk factors for postoperative spinal infections. Infections in the setting of instrumentation are more difficult to diagnose and treat due to biofilm. Infections may be early or delayed. C Reactive Protein (CRP) and Magnetic Resonance Imaging (MRI) are important diagnostic tools. Optimal results are obtained with surgical debridement followed by parenteral antibiotics. Removal or replacement of hardware should be considered in delayed infections.

Conclusions:

An improved understanding of the role of biofilm and the development of newer spinal implants has provided insight in the pathogenesis and management of infected spinal implants. This literature review highlights the mechanism, pathogenesis, prevention, and management of infection after spinal instrumentation. It is important to accurately identify and treat postoperative spinal infections. The treatment is often multimodal and prolonged.

The difference of surgical site infection according to the methods of lumbar fusion surgery

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

To compare the rates and types of a surgical site infection according to the surgical options in spine surgeries.

SUMMARY OF BACKGROUND DATA

Scant literatures exist on the difference of surgical site infection according to the surgical methods. We presumed that the incidence of infection after posterior lumbar interbody fusion (PLIF) was higher than posterior or posterolateral fusion (PF, PLF) due to several reasons.

METHODS

A retrospective analysis was made on the patients who received instrumented spinal fusion surgeries from 2000 to 2009. The differences of surgical site infection rates and characteristics were compared between the patients who received PF or PLF (group I) and PLIF (group II). In addition, the infection rate according to the graft options and number of cages was compared in group II.

RESULTS

A significant difference (P = 0.003) of infection rate between group I (0.3%, 3 cases out of 974) and group II (1.37%, 29 cases out of 2110) was observed. In group I, 67% of infections were wound infections and 33% were osteomyelitis. In group II, 23% were wound infections, 73% were osteomyelitis, and 4% were osteomyelitis combined with wound infection. Significant increase of infection rate was observed in the single cage group (P = 0.001) and mainly local bone grafted group (P = 0.030).

CONCLUSIONS

The infection rate of PLIF was higher than that of PF or PLF. Considering the increased infection rate in local bone grafted group and 52% of the infection cases after interbody fusion was osteomyelitis around interbody space, contaminated local bones and interbody space were suspected as major routes of contamination. The higher infection rate in single cage group than that of double cage group was attributed to vulnerability of remained avascular disk materials to infection.

Complications associated with posterior and transforaminal lumbar interbody fusion

Posterior lumbar interbody fusion and transforaminal lumbar interbody fusion are commonly performed to obtain a 360° arthrodesis through a posterior-only approach. These techniques are currently used in the management of spondylolisthesis, degenerative scoliosis, pseudarthrosis, recurrent disk herniation, and chronic low back pain with associated degenerative disk disease. Several adverse events have been described, including intraoperative neurologic injury, implant migration or subsidence, dural tears, infection, heterotopic ossification, BMP-related radiculitis, and osteolysis. Although the use of newer materials (eg, bone morphogenetic proteins) and procedures (eg, minimally invasive surgery) is on the rise, they are associated with unique concerns. Understanding the potential adverse events and steps that can be taken to prevent, detect, and manage complications is critical in patient counseling and perioperative decision making.

Manejo de la migración posterior de los dispositivos intersomáticos colocados por vía posterior (PLIF): análisis bibliográfico

OBJETIVO: Se tiene la finalidad de presentar el cuadro clínico de tres casos de esta complicación y analizar metodológicamente los trabajos existentes en la bibliografía. MÉTODO: Tres pacientes operados de columna lumbar a quienes se les realizó una artrodesis circunferencial y que presentaron en el posoperatorio, después de bastante tiempo, nueva sintomatología relacionada con la migración de uno o de los dos PLIF. RESULTADOS: Se realizó mediante el abordaje por vía anterior retroperitoneal, para disectomía, retiro de material migrado y colocación de un dispositivo intersomático anterior. En el primer caso se asoció un abordaje posterior para el retiro del material de osteosíntesis. Se realizó una búsqueda bibliográfica para analizar los datos sobre el retiro según parámetros de evidencia científica. CONCLUSIONES: No existen publicaciones de Evidencia tipo 1 o 2 que marquen directivas claras. La presencia de fibrosis posquirúrgica orientaría al abordaje por vía anterior en el retiro de los dispositivos intersomáticos y así evitaría las lesiones del saco dural y la elongación radicular. La dificultad del manejo vascular y el riesgo de eyaculación retrógrada en pacientes del sexo masculino son parámetros a tener en cuenta para optar por el abordaje posterior. El retiro de los PLIF migrados a posterior, que causen sintomatología dolorosa y/o deficitaria, se convierte en una práctica altamente exigente y de manejo dificultoso.

A biofilm approach to detect bacteria on removed spinal implants

STUDY DESIGN

This is a prospective study comparing the diagnosis of spinal implant infection by conventional peri-implant tissue culture with a technique which uses a combination of vortexing and bath sonication to dislodge bacteria growing as a biofilm on the surface of retrieved spinal implants.

OBJECTIVE

We hypothesized that the biofilm-sampling technique would be more sensitive than peri-implant tissue culture.

SUMMARY OF BACKGROUND DATA

Culture of peri-implant tissue is inaccurate for the diagnosis of orthopedic device-related infection; cultures taken from the implant may be more sensitive. We have developed a technique which uses vortexing-bath sonication to sample bacterial biofilms on the surface of retrieved hip and knee implants, and shown that it is more sensitive than peri-prosthetic tissue culture for the microbiologic diagnosis of prosthetic knee, hip, and shoulder infection.

METHODS

We compared peri-implant tissue culture to the vortexing-bath sonication technique which samples bacterial biofilm on the surface of retrieved spinal implants, for the diagnosis of spinal implant infection. In addition, we compared detection of Staphylococcus and Propionibacterium acnes by rapid cycle real-time polymerase chain reaction with culture of sonicate fluid.

RESULTS

A total of 112 subjects were studied; 22 had spinal implant infection. The sensitivities of peri-implant tissue and sonicate fluid culture were 73% and 91% (P = 0.046), and the specificities were 93% and 97%, respectively. P. acnes and coagulase-negative staphylococci were the most frequent microorganisms detected among subjects with spinal implant infection, with P. acnes detected in 56 and 45%, and coagulase-negative staphylococci detected in 31 and 40% of peri-implant tissue and sonicate fluid cultures, respectively. Compared with the culture of sonicate fluid, polymerase chain reaction was 100 and 67% sensitive for the detection of culture-positive Staphylococcus and P. acnes spinal implant infection, respectively.

CONCLUSION

Implant sonication followed by culture is more sensitive than peri-implant tissue culture for the microbiologic diagnosis of spinal implant infection.

Surgical site infection rates after minimally invasive spinal surgery

OBJECT

Postoperative surgical site infections (SSIs) have been reported after 2-6% of spinal surgeries in most large series. The incidence of SSI can be < 1% after decompressive procedures and > 10% after instrumented fusions. Anecdotal evidence has suggested that there is a lower rate of SSI when minimally invasive techniques are used.

METHODS

A retrospective review of prospectively collected databases of consecutive patients who underwent minimally invasive spinal surgery was performed. Minimally invasive spinal surgery was defined as any spinal procedure performed through a tubular retractor system. All surgeries were performed under standard sterile conditions with preoperative antibiotic prophylaxis. The databases were reviewed for any infectious complications. Cases of SSI were identified and reviewed for clinically relevant details. The incidence of postoperative SSIs was then calculated for the entire cohort as well as for subgroups based on the type of procedure performed, and then compared with an analogous series selected from an extensive literature review.

RESULTS

The authors performed 1338 minimally invasive spinal surgeries in 1274 patients of average age 55.5 years. The primary diagnosis was degenerative in nature in 93% of cases. A single minimally invasive spinal surgery procedure was undertaken in 1213 patients, 2 procedures in 58, and 3 procedures in 3 patients. The region of surgery was lumbar in 85%, cervical in 12%, and thoracic in 3%. Simple decompressive procedures comprised 78%, instrumented arthrodeses 20%, and minimally invasive intradural procedures 2% of the collected cases. Three postoperative SSIs were detected, 2 were superficial and 1 deep. The procedural rate of SSI for simple decompression was 0.10%, and for minimally invasive fusion/fixation was 0.74%. The total SSI rate for the entire group was only 0.22%.

CONCLUSIONS

Minimally invasive spinal surgery techniques may reduce postoperative wound infections as much as 10-fold compared with other large, modern series of open spinal surgery published in the literature.

Evolução clínica e funcional dos pacientes com infecção após artrodese de coluna lombar

OBJETIVOS: descrever a experiência dos autores no manejo da infecção após instrumentação da coluna lombar e suas consequências futuras. MÉTODOS: estudo de coorte prospectivo com pacientes portadores de infecção profunda pós-operatória, realizado entre janeiro de 1997 e janeiro de 2009. Todos os pacientes foram submetidos à revisão cirúrgica, coleta de material para exame microbiológico, lavagem exaustiva da região, debridamento dos tecidos desvitalizados, colocação de sistema de lavagem contínua, sutura primária e antibioticoterapia. Manteve-se a instrumentação em todos os pacientes. Os pacientes foram avaliados durante o seguimento por imagens radiográficas, estado clínico e funcional. Utilizaram-se a escala numérica da dor e o índice de incapacidade Oswestry. Os resultados numéricos foram submetidos a análises pareadas pelo teste de Wilcoxon. RESULTADOS: a incidência de infecção foi de 3,1% (15/485). O agente etiológico mais prevalente foi o Staphylococcus aureus. Todos os casos lograram consolidação. Em um seguimento médio de 47,6 meses, observaram-se mudanças nos escores da escala numérica da dor (p=0,001) e índice de incapacidade Oswestry (p=0,017). Na avaliação final, 64,2% dos pacientes (9/14) apresentaram incapacidade mínima e 35,8% (5/14), incapacidade moderada. CONCLUSÃO: o tratamento agressivo das infecções pós-operatórias de artrodese de coluna lombar permite evitar a retirada da instrumentação e manter a estabilidade vertebral. A despeito da complicação, os pacientes apresentaram melhoras em relação à dor e capacidade funcional pré-operatórias.

Clinical outcome of deep wound infection after instrumented posterior spinal fusion: a matched cohort analysis

STUDY DESIGN

Retrospective case control study.

OBJECTIVE

Determine the impact of infection on clinical outcome in patients undergoing posterior spinal fusion surgery.

SUMMARY OF BACKGROUND DATA

The outcome of patients treated for infection after spinal surgery is not well established because of variability in cohort identification, definition of infection, outcomes instrument, use of a control group, and/or sample size.

METHODS

Thirty-two patients were included. Sixteen patients ("infection group") met inclusion criteria of deep wound infection after spinal fusion with posterior segmental instrumentation (including combined approach). A 1:1 matched cohort ("control group") was created based on primary or revision status, length of fusion, diagnosis, and age. Postoperative patient outcomes were evaluated using the physical components of SF-36 v2.0 with minimum 2-year follow-up.

RESULTS

No significant difference in the Physical Function, Role Physical, Bodily Pain, and General Health domains was detected between the infection group and control group. Mean follow-up was 62 months. Mean Physical Component Summary was 41.4 in the infection group and 44.3 in the control group (P = 0.6). Infection occurred early in 12 patients and late in 4 patients. Most common organisms isolated were Staphylococcus epidermidis, Enterococcus sp., and Staphylococcus aureus. Multiple debridements were significantly associated with polymicrobial infections and later pseudarthrosis requiring reoperation.

CONCLUSION

An aggressive approach to deep wound infection emphasizing early irrigation and debridement allowed preservation of instrumentation and successful fusion in most cases. At the conclusion of treatment, patients can expect a medium-term clinical outcome similar to patients in whom this complication did not occur.