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

BACKGROUND

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

LEVEL OF EVIDENCE

IV.

Assessing Alignment Using GAP Score and Complications for Pedicle Subtraction Osteotomy Revision Surgeries for Sagittal Deformity in Previously Fused Spines Using a Satellite Rod Technique

OBJECTIVE

Pedicle subtraction osteotomy (PSO) is a surgical technique to restore lumbar lordosis in patients with rigid sagittal deformity. Herein, we report on outcomes of a surgical technique utilizing a 4-rod PSO with satellite rods.

METHODS

A retrospective study was performed for a cohort of patients who underwent 4-rod PSO revision surgery for sagittal deformity. Procedures were performed by one surgeon at 2 different academic centers between 2004-2018. Alignment outcomes and complications specifically for revision surgeries in previously fused spines were assessed.

RESULTS

40 patients underwent PSO with the satellite rod technique (n = 29 at L3, 72.5%; n = 7 at L4, 17.5%). Mean PSO angle was 28.7 ± 7.6°. Two patients (5%) had rod fracture necessitating revision surgery at 32 and 34 months. Three patients (7.5%) developed proximal junctional kyphosis (PJK), but none required revision. No patients developed pseudoarthrosis. Mean preoperative sagittal vertical axis (SVA) was 13.5 ± 7.3 cm, which decreased to 4.8 ± 7.3 cm (P = 0.002) postoperatively. Mean preoperative pelvic incidence-lumbar lordosis (PI-LL) mismatch improved from 35.9 ± 16.6° preoperatively to 11.8 ± 14.6° postoperatively (P < 0.001). Mean preoperative pelvic tilt (PT) improved from 34.7 ± 9.8° preoperatively to 30.1 ± 9.0° (P = 0.026) postoperatively. Mean global alignment and proportion (GAP) score improved from 10 ± 2 preoperatively to 8 ± 2 postoperatively (P < 0.001), which was still considered severely disproportioned.

CONCLUSIONS

Rod failure rate after PSO with the 4-rod satellite configuration was low. SVA, PI-LL mismatch, and PT significantly improved for these previously-fused patients. Mean GAP score also improved, but was still considered severely disproportioned, likely due to the inability of PSO to correct low LL or PT in previously-fused spines.

Surgical outcomes of anterior lumbar interbody fusion in revision lumbar interbody fusion surgery

BACKGROUNDS

Anterior lumbar interbody fusion (ALIF) is an attractive option for revision lumbar interbody fusion as it provides wide access for implant removal and accommodation of large interbody grafts for fusion. However, revision lumbar interbody fusion surgery has not been found to result in significantly better functional outcomes compared with other approaches. To date, no prognostic factors of anterior lumbar interbody fusion in revision lumbar interbody fusion have been reported. In this study, we investigated the surgical results and possible prognostic factors of anterior lumbar interbody fusion in revision lumbar interbody fusion.

METHODS

Patients who received revision interbody fusion surgery between January 2010 and May 2018 in our hospital were reviewed. Clinical outcomes were determined according to whether the VAS score improvement in back pain and leg pain reached the minimum clinically important difference (MCID) and Macnab criteria. Radiographic outcomes were assessed with fusion rate, preoperative, and postoperative lumbar lordosis. Operative-relative factors that may affect clinical outcomes, such as BMI, existence of cage migration, cage subsidence, pseudarthrosis, previous procedure, and number of fusion segments, were collected and analyzed.

RESULTS

A total of 22 consecutive patients who received ALIF for revision interbody fusion surgery were included and analyzed. There were 9 men and 13 women with a mean age at operation of 56 years (26-78). The mean follow-up was 73 months (20-121). The minimal clinically important difference (MCID) was reached in 11 (50%) of the patients for back pain and 14 (64%) for leg pain. According to the modified Macnab criteria, 73% of the patients in this study had successful outcomes (excellent or good). The pain and lumbar lordosis had significant improvement (P < 0.05). Preoperative fusion segment ≥ 2 was shown to be a poor prognostic factor for back pain improvement reaching MCID (P = 0.043).

CONCLUSIONS

ALIF has proven effective for revision lumbar fusion surgery, yielding positive clinical and radiographic results. However, having two or more preoperative fusion segments can negatively impact back pain improvement.

LEVEL OF EVIDENCE

IV.

Unexpected intraoperative positive culture (UIPC) in presumed aseptic revision spine surgery: a systematic review and meta-analysis

BACKGROUND CONTEXT

Unexpected intraoperative positive culture (UIPC) has recently become increasingly common in revision spine surgery, being implicated as an etiological factor in revision spine surgery indications such as implant failure or pseudoarthrosis.

PURPOSE

Utilizing the available literature, this study aimed to investigate the prevalence of UIPC, and its clinical importance in patients following presumed aseptic revision spine surgery.

STUDY DESIGN

Meta-analysis and systematic review.

METHODS

Multiple databases and reference articles were searched until May 2022. The primary outcome was the pooled rate of UIPC, and the secondary outcomes were the microbiological profile of UIPC, the risk factors of UIPC, and the clinical fate of UIPC.

RESULTS

Twelve studies were eligible for meta-analysis, with a total of 1,108 patients. The pooled rate of UIPC was 24.3% (95% CI=15.8%-35.5%) in adult patients, and 43.2% (95% CI=32.9%-54.2%) in pediatric patients. The UIPC rate was higher when both conventional wound culture and sonication were used together compared to sonication alone or conventional wound culture alone. The rates were 28.9%, 23.6%, and 15.5 %, respectively. In adult and pediatric patients, the most commonly cultured organism was Cutibacterium acnes (42.5% vs 57.7%), followed by coagulase-negative Staphylococcus (39.9% vs 30.5%). Male patients had a higher rate of UIPC (OR= 2.6, 95% CI=1.84-3.72, p<.001), as did patients with a longer fusion construct (MD=0.76, 95% CI=0.27-1.25, p<.001).

CONCLUSIONS

The pooled rate of UIPC in aseptic spine revision surgery was 24.3% and 43.2% in adult and pediatric patients respectively. The most common organisms were C. acnes and coagulase-negative Staphylococcus. The impact of UIPC on patients` clinical outcomes is not fully understood. We are not able to recommend routine culture in revision spine surgery, however, adding sonication may aid in the diagnosis of UIPC. There is not enough evidence to recommend specific treatment strategies at this time, and further studies are warranted.

Long spine fusions to the sacrum-pelvis are associated with greater post-operative proximal junctional kyphosis angle in sitting position

STUDY DESIGN

A single-centre retrospective study.

BACKGROUND AND PURPOSE

Although adult patients spend most of their time in sitting positions, the assessment of spinopelvic parameters in adult deformity surgery is commonly performed in standing X-rays. Our study compares the standing and sitting sagittal alignment parameters in subjects who underwent thoracolumbar fusion.

METHODS

Patients who underwent corrective surgery for adult scoliosis with at least five instrumented vertebra were stratified according to the upper instrumented vertebra (UIV) and pelvic fixation. Group A:UIV proximal to T6 with pelvis fixation. B:UIV lower than T6 and pelvic fixation. Group C: thoracolumbar fusion without pelvic fixation. Post-operative spinopelvic sagittal parameters were measured in both standing and sitting X-rays.

RESULTS

A total of 51 patients were enrolled in the study (11:Males and 40:Females). The mean age was 52.3 ± 21.7y/o. The comparison of post-operative standing and sitting X-ray within the group A and B showed that a significant change was observed in terms of JA-Junctional Angle-(Group A 6.3 ± 4.3 vs. 8.1 ± 3.3, p value = 0.03) (Group B 8.5 ± 6.4 vs. 10.9 ± 6.4, p value = 0.02). Group C showed statistically significant difference in terms of PT (15.6 ± 11.2 vs. 19.3 ± 9.2, p value = 0.04), AVA-Acetabular Version Angle-(41.1 ± 5.9 vs. 48.3 ± 6.6, p value < 0.01) and LL (- 51.3 ± 16.0 vs. - 42.6 ± 10.7, p value < 0.01).

CONCLUSION

In our series, the post-operative sagittal alignment showed peculiar behaviours and adaptations in sitting position, depending on the length and the site of the instrumented area. If the pelvis is included, the JA tends to significantly increase in sitting position. These findings can improve the knowledge of pathologies as proximal junctional kyphosis or specific cases of anterior hip impingement.

LEVEL OF EVIDENCE

IV.

The Collective Influence of Social Determinants of Health on Individuals Who Underwent Lumbar Spine Revision Surgeries: A Retrospective Cohort Study

OBJECTIVE

To analyze the collective effect of social determinants of health (SDH) on lumbar spine revision surgery outcomes using a retrospective cohort study design.

METHODS

Data from the Quality Outcomes Database were used, including 7889 adults who received lumbar spine revision surgery and completed 3 and 12 months' follow-up. The SDH of interest included race/ethnicity, educational attainment, employment status, insurance payer, and sex. A stepwise regression model using each number of SDH conditions present (0 of 5, 1 of 5, 2 of 5, ≥3 of 5) was used to assess the collective influence of SDH. The odds of demonstrating a minimum clinically important difference was evaluated in back and leg, disability, quality of life, and patient satisfaction at 3-months and 12-months follow-up.

RESULTS

An additive effect for SDH was found across all outcome variables at 3 and 12 months. Individuals with ≥3 SDH were at the lowest odds of meeting the minimum clinically important difference of each outcome. At 12 months, individuals with ≥3 SDH had a 67%, 65%, 71%, 65%, and 46% decrease in the odds of a clinically meaningful outcome in back and leg pain, disability, quality of life, and patient satisfaction.

CONCLUSIONS

Health care teams should evaluate SDH in individuals who may be considered for lumbar spine revision surgery. Viewing social factors in aggregate may be useful as a screening tool for lumbar spine revision surgeries to identify at risk patients who may require pre-emptive care strategies and postoperative resources to mitigate these risks.

Independent Predictors of Revision Lumbar Fusion Outcomes and the Impact of Spine Surgeon Variability: Does It Matter Whether the Primary Surgeon Revises?

BACKGROUND

There is a paucity of information regarding treatment strategies and variables affecting outcomes of revision lumbar fusions.

OBJECTIVE

To evaluate the influence of primary vs different surgeon on functional outcomes of revisions.

METHODS

All elective lumbar fusion revisions, March 2018 to August 2019, were retrospectively categorized as performed by the same or different surgeon who performed the primary surgery. Oswestry Disability Index (ODI) and clinical variables were collected. Multiple logistic regression identified multivariable-adjusted odds ratio (OR) of independent variables analyzed.

RESULTS

Of the 130 cases, 117 (90%) had complete data. There was a slight difference in age in the same (median: 59; interquartile range [IQR], 54-66) and different surgeon (median: 67; IQR, 56-72) groups (P = .02); all other demographic variables were not significantly different (P > .05). Revision surgery with a different surgeon had an ODI improvement (median: 8; IQR, 2-14) greater than revisions performed by the same surgeon (median: 1.5; IQR, -3 to 10) (P < .01). Revisions who achieved minimum clinically important difference (MCID) performed by different surgeon (59.7%) were also significantly greater than the ones performed by the same surgeon (40%) (P = .042). Multivariate analysis demonstrated that a different surgeon revising (OR, 2.37; [CI]: 1.007-5.575, P = .04) was an independent predictor of MCID achievement, each additional 2 years beyond the last surgery conferred a 2.38 ([CI]: 1.36-4.14, P < .01) times greater odds of MCID achievement, and the anterior lumbar interbody fusion approach decreased the chance of achieving MCID (OR, 0.19; [CI]: 0.04-0.861, P = .03).

CONCLUSION

All revision lumbar spinal fusion approaches may not achieve the same outcomes. This analysis suggests that revision surgeries may have better outcomes when performed by a different surgeon.

Anterior Lumbar Interbody Fusion (ALIF) L5-S1 with overpowering of posterior lumbosacral instrumentation and fusion mass: a reliable solution in revision spine surgery

BACKGROUND AND PURPOSE

In cases of spine surgical revisions of patients affected by sagittal malalignment, the restoration of the ideal lumbar lordosis (LL) is mandatory. ALIF procedures represent a powerful and effective approach to improve the LL in case of hypolordosis. This study evaluates the feasibility of ALIF to overpower posterior lumbar instrumentation and fusion mass in revision spine surgery and secondarily to estimate complications, clinical and radiological outcomes.

METHODS

This is a single-center retrospective analysis of prospectively collected data on the use of ALIF overpowering in cases of lumbosacral instrumentation and/or fusion. Demographic, comorbidity, corrective strategy adopted, surgical data, clinical and radiological results, and intraoperative and postoperative complications were recorded.

RESULTS

Twelve patients (3 male; 9 female) underwent overpowering ALIF L5-S1 were included in the study with a mean FU of 34.0 ± 13.4 months. In 10 cases, a posterior titanium instrumentation and fusion mass were present; in 2 patients, only a fusion mass was present. Indicators of pain and disability improved in all patients (p < 0.01). Sagittal realignment with the restoration of ideal spinopelvic parameters was obtained in all cases. One peritoneal lesion requiring intraoperative suture without sequelae, two cases of postoperative radiculopathy, and one posterior wound infection requiring surgical debridement and antibiotic therapy were reported.

CONCLUSIONS

Anterior implant of lordotic and hyperlordotic cages with increasing segmental lordosis is possible in the presence of posterior instrumentation and/or solid fusion mass. The biomechanical strength of this corrective technique can overcome posterior instrumentation and bone fusion resistance, therefore allowing a single-staged surgery for sagittal realignment.

Comprehensive treatment algorithm of postoperative spinal implant infection

Postoperative spinal implant infection (PSII) is a commonly found and serious complication after instrumented spinal surgery. Whereas early-onset PSII usually can be diagnosed by clinical symptoms, the diagnosis of late-onset PSII can be often made only by examination of intraoperatively collected samples. The treatment of PSII consists of surgical and antibiotic therapy schemes. In case of early PSII, the retention of spinal implants is a feasible option, whereas late PSII is usually treated by one-staged exchange of the spinal implants. Radical debridement of surrounding tissue should be performed in any case of PSII. The antibiotic treatment depends on either the implants can be removed or need to be retained or exchanged, respectively. If the causative pathogens are sensitive for biofilm-active antibiotic agents, the duration of antibiotic treatment amounts to 12 weeks with retention of spinal implants. In case of problematic pathogens, the application of antibiotics needs to be prolonged for an individual duration. Antibiotic treatment should always be initiated with an intravenous application for at least 2 weeks.

Malpositioned pedicle screw in spine deformity surgery endangering the aorta: report of two cases, review of literature, and proposed management algorithm

STUDY DESIGN

Case reports and review of the literature with a proposed management algorithm.

OBJECTIVES

To report two cases of a potential vascular complication due to an incorrectly placed pedicle screw (PS) during spine deformity surgery. Relevant literature regarding the management of vascular complications is reviewed, and an evidence-based management algorithm is proposed. Aortic lesions represent a rare but potentially life-threatening complications with spine deformity and revision surgery, significantly increasing the risk. A management algorithm for an aortic lesion in the case of a malpositioned PS has not yet been published.

METHODS

Case 1: An 18-year-old female with proximal thoracic spinal non-instrumented fusion underwent a revision corrective procedure due to a progressive right-sided thoracolumbar compensatory curve. However, postoperative computed tomography (CT) performed to evaluate the position of the PS revealed malposition of the left T9 PS, which was abutting the descending aorta with CT angiography excluding the perforation of the aorta. Case 2: A 17-year-old male was scheduled for correction of Lenke 3-C-N adolescent idiopathic scoliosis. Postoperative routine evaluation with low-dose CT revealed a left T9 PS paravertebral malposition, and subsequent CTA demonstrated that the thread of the PS was in contact with the descending thoracic aorta and an unlikely hemodynamically significant vessel injury.

RESULTS

Successful removal of both malpositioned PS was performed. In the first case, a cardiovascular surgeon attended the operation if an urgent thoracotomy was needed, and in the second case, additional video-assisted thoracoscopic control of the aorta was performed during PS removal.

CONCLUSIONS

Preoperative imaging in spinal surgery is essential to avoid major vascular and other complications when placing PS, especially in thoracic deformities. When a potential major vessel complication emerges, an interdisciplinary approach and an appropriate management algorithm are mandatory to make the best clinical decisions.

LEVEL OF EVIDENCE

4.

Low sensitivity of histopathological examination of peri-implant tissue samples in diagnosing postoperative spinal implant infection

AIMS

To evaluate the histopathological examination of peri-implant tissue samples as a technique in the diagnosis of postoperative spinal implant infection (PSII).

METHODS

This was a retrospective analysis. Patients who underwent revision spinal surgery at our institution were recruited for this study. PSII was diagnosed by clinical signs, histopathology, and microbiological examination of intraoperatively collected samples. Histopathology was defined as the gold standard. The sensitivity for histopathology was calculated. A total of 47 patients with PSII and at least one microbiological and histopathological sample were included in the study.

RESULTS

PSII occurred in approximately 28% of the study population. Histopathology showed a sensitivity of 51.1% in the diagnosis of PSII. The most commonly found pathogens were Cutibacterium acnes and gram-positive staphylococci.

CONCLUSION

Histopathology has low sensitivity for detecting PSII. In particular, infections caused by low-virulence microorganisms are insufficiently detected by histopathology. Cite this article: Bone Joint J 2020;102-B(7):899-903.

Posterior lumbar interbody fusion graft penetrated the lumbar thecal sac in a patient with rheumatoid arthritis: A case report

INTRODUCTION

Intradural foreign bodies have been reported to be associated with disc material, tumors, and bullets following spinal gunshot injuries. In this report, we describe a case of non-union with minor trauma that caused interbody bone graft material to migrate into the intrathecal area in a patient with RA.

PRESENTATION OF CASE

We present the case of a 65-year-old woman visited an outpatient clinic of our hospital after experiencing progressive lower extremity weakness, and voiding and defecation difficulty after fell down several times in the past. She had a history of two spinal decompression with fixation surgeries due to spinal stenosis with a herniated intervertebral disc. She was prescribed steroids and methotrexate for the RA. The results of MRI and CT demonstrated an intradural bone graft material migration with cauda equina syndrome after revision lumbar stenosis surgery. Calcified material protruded to the intracanal area and compressed the cauda equina fiber. After the removal of fragments operation, she recovered from cauda equina symptoms. A follow-up examination two years postoperatively revealed clinical resolution of cauda equina symptoms and a return to partial walking with a cane.

DISCUSSION

The patient had a minor or major trauma, such as a fall, after the revision surgery. After that trauma, the patient presented with some dural injury, kyphotic position, or non-union state causing the dural penetration of the interbody fusion material.

CONCLUSION

The first report describing displaced PLIF graft material that penetrated the dural sac and caused cauda equina symptoms in a patient with RA. Establishing strategies to minimize these complications is indicated when treating degenerative lumbar spine conditions in patients with RA.

Pedicled, vascularized occipital bone graft to supplement atlantoaxial arthrodesis for the treatment of pseudoarthrosis

Atlantoaxial pseudoarthrosis is a challenging postoperative complication. The use of a local, vascularized bone graft, without free tissue transfer, to support a revision atlantoaxial fusion has not been previously described. We report the first surgical patient who received a semispinalis capitis muscle pedicled, occipital bone graft for supplementation of a revision atlantoaxial arthrodesis. A 72-year-old female had a failed atlantoaxial fusion and developed neck pain from continued instability and fractured hardware. The fixation and fusion were revised and supplemented with a novel, pedicled occipital bone graft. A craniectomy was performed in the occipital bone while still attached to the semispinalis capitis muscle to provide graft vascularity. This graft was rotated inferiorly from the skull base to the C1 arch and C2 spinous process in order to supplement a revision atlantoaxial arthrodesis. The patient had excellent clinical recovery over 18-month clinical follow up. The bone graft harvesting and rotation were performed safely and without complication. The 6-month postoperative CT scan showed partial fusion into the graft. This novel surgical technique leverages the advantages of vascularized structural autograft without adding extensive time or morbidity to the procedure as observed in free-tissue transfers. It is a safe and useful salvage technique to supplement revision atlantoaxial fusion surgeries.

Postoperative Radiographic Evaluation Following Adult Spine Deformity Correction: The Impact on Subsequent Management and Associated Risk of Radiation Exposure

BACKGROUND

During the follow-up visits after Adult Spine Deformity (ASD) surgery, obtaining surveillance radiographs is a usual practice, and this study tried to identify evidence to support or refute such practice.

METHODS

This is a retrospective, diagnostic case series (Level IV) of 49 patients. We identified the abnormal radiographic findings and their association with need for revision surgery. We determined the odds of obtaining an abnormal radiographs that lead to revision surgery at each of the given time intervals of follow-up. We also estimated the risk versus benefit of obtaining radiographs at each of the given time intervals of follow-up.

RESULTS

We identified a total of 11 individual types of abnormal postoperative radiographic findings. Of them, the two radiographic findings that always needed revision surgery because of the associated clinical presentation were pedicle screw pullout and bilateral rod fracture. One abnormal radiographic finding that was never associated with revision surgery was the halo around a pedicle screw. In each of the given postoperative time intervals of follow-up at which the routine radiographs were obtained, we noted that the odds of noticing abnormal radiographic finding that lead to revision surgery was always >1. We found that the cumulative hazard rate for exposure to radiation was significantly higher during the initial follow-up visits when compared to subsequent follow-up visits.

CONCLUSION

This study finds evidence to support the practice of routine postoperative radiographic evaluation of patients who come for follow-up after ASD surgery.

Microbiologic profile of infections in presumed aseptic revision spine surgery

PURPOSE

Intra-operative cultures may be obtained in revision spine surgery despite the absence of pre-operative clinical markers of infection. The microbiologic profile of culture positive cases in which there is no clear evidence of infection preoperatively has not been described. The aim of this investigation is to report on the microbiologic profile of unexpected culture positive revision spine surgery cases.

METHODS

We retrospectively reviewed 595 consecutive revision spine surgeries performed between 2008 and 2013. Five hundred and seventy-eight revision surgeries were performed for diagnoses other than infection and were included in the study.

RESULTS

Operative cultures were obtained in 112 cases (19.4 %). Cultures were positive in 45 cases. Pseudarthrosis was not only the most common diagnosis overall (49.1 %) in which intra-operative cultures were obtained, it was also the most common revision surgical diagnosis where cultures were positive (55.6 %). Propionibacterium acnes was cultured in 54.2 % of cases with the primary diagnosis of pseudarthrosis, but only in 40.9 % of cases with other diagnoses (P = 0.554). Overall, staphylococcal species were found most commonly (57.8 % of cases), but P. acnes was at least one of the isolates in 48.9 % of cases and was three times more common than any other organism.

CONCLUSIONS

Nearly one in five patients with the diagnosis of pseudarthrosis were culture positive. More specifically, pseudarthrosis was the most common culture positive diagnosis and P. acnes species predominated in this patient population. Propionibacterium acnes was overwhelmingly the most common single organism cultured in revision spine surgery. Given this, we recommend all cultures be held for P. acnes, particularly in the setting of pseudarthrosis.

The value of intraoperative Gram stain in revision spine surgery

BACKGROUND CONTEXT

Intraoperative cultures and Gram stains are often obtained in cases of revision spine surgery even when clinical signs of infection are not present. The clinical utility and cost-effectiveness of this behavior remain unproven.

PURPOSE

The aim was to evaluate the clinical utility and cost-effectiveness of routine intraoperative Gram stains in revision spine surgery.

STUDY DESIGN

This was a retrospective clinical review performed at an academic center in an urban setting.

PATIENT SAMPLE

One hundred twenty-nine consecutive adult revision spine surgeries were performed.

OUTCOME MEASURES

The outcome measures included intraoperative Gram stains.

METHODS

We retrospectively reviewed the records of 594 consecutive revision spine surgeries performed by four senior surgeons between 2008 and 2013 to identify patients who had operative cultures and Gram stains performed. All revision cases including cervical, thoracic, and lumbar fusion and non-fusion, with and without instrumentation were reviewed. One hundred twenty-nine (21.7%) patients had operative cultures obtained and were included in the study.

RESULTS

The most common primary diagnosis code at the time of revision surgery was pseudarthrosis, which was present in 41.9% of cases (54 of 129). Infection was the primary diagnosis in 10.1% (13 of 129) of cases. Operative cultures were obtained in 129 of 595 (21.7%) cases, and 47.3% (61 of 129) were positive. Gram stains were performed in 98 of 129 (76.0%) cases and were positive in 5 of 98 (5.1%) cases. Overall, there was no correlation between revision diagnosis and whether or not a Gram stain was obtained (p=.697). Patients with a history of prior instrumentation were more likely to have a positive Gram stain (p<.0444). Intraoperative Gram staining was found to have a sensitivity of 10.9% (confidence interval [CI] 3.9%-23.6%) and specificity of 100% (CI 93.1%-100%). The positive and negative predictive values were 100% (CI 48.0%-100%) and 57.3% (CI 45.2%-66.2%), respectively. Kappa coefficient was calculated to be 0.1172 (CI 0.0194-0.2151). The cost per discrepant diagnosis (total cost/number discrepant) was $172.10.

CONCLUSIONS

This study demonstrates that while very specific for infection, the sensitivity of intraoperative Gram staining is low, and agreement between positive cultures and Gram stains is very poor. Gram staining demonstrated limited cost-effectiveness because of the low prevalence of findings that altered patient management.

Reduction of epidural fibrosis and dural adhesions after lamina reconstruction by absorbable cement: an experimental study

BACKGROUND CONTEXT

Post-laminectomy epidural fibrosis complicates revision spine surgery and is implicated in cases of "failed back syndrome." Several materials have been used to minimize epidural fibrosis with varying results.

PURPOSE

The aim of this study was to examine the impact of reconstruction of laminectomy site with a type of absorbable cement (Jectos) to reduce epidural fibrosis.

STUDY DESIGN

This investigation is an experimental controlled study, which is designed to evaluate the preventive effects of laminectomy site reconstruction in rat laminectomy model.

METHODS

Twenty wistar rats were included in this study and divided randomly to two equal groups, namely, subject and control. In both groups, laminectomy was performed in L2 and L4 levels. Control group received no additional treatment. In the subject group, L4 levels were reconstructed by Jectos and L2 levels were non-reconstructed as internal controls. Six months after surgery the rats were sacrificed and the dural adhesion and epidural fibrosis were evaluated macroscopically and microscopically. The study was financially supported by Brain and Spinal Cord Injuries Repair Center. None of the authors have any conflict of interest.

RESULTS

Non-reconstructed levels in both groups showed dense epidural fibrosis with marked dural adherence. L4 reconstructed levels in subject group showed reduced epidural fibrosis macroscopically (p=.024) and microscopically (p=.041). No foreign body reaction or ossification occurred at reconstructed sites.

CONCLUSIONS

In the present study, lamina reconstruction with absorbable cement was a safe method that significantly reduced post-laminectomy epidural fibrosis and dural adhesions in rat laminectomy model.