Severity of Preoperative HbA1c and Predicting Postoperative Complications in Spine Surgery.

BACKGROUND: Diabetes mellitus (DM) is associated with a greater incidence of perioperative complications. The measurement of hemoglobin A1c (HbA1c) has not been routinely used in the preoperative assessment for spine surgeries. METHODS: In the present single-institution, prospective study, HbA1c testing was included in the preoperative laboratory examination of patients undergoing spinal surgery from 2016 through 2018. The HbA1c levels were categorized using the American Diabetes Association guidelines as normal (HbA1c <5.7%), pre-DM (HbA1c 5.7%-6.4%), and diabetes (HbA1c >6.5%). Those with a HbA1c of ≥8% were separated as having poorly controlled DM for analysis. Perioperative complication and comorbidity data were collected to assess for associations with DM using logistic regression models. Odds ratios (ORs) and 95% confidence intervals were computed. RESULTS: A total of 440 patients (238 men, mean age, 56.43 ± 13.28 years; mean body mass index, 30.80 ± 6.65 kg/m2) met the study criteria. The HbA1c was <5.7% in 206 patients (46.8%), 5.7%-6.4% in 148 (33.6%), 6.5%-7.9% in 64 (14.5%), and ≥8.0% in 23 patients (5.22%). Bivariate logistic modeling showed that patients with poorly controlled DM had a higher risk of complications (OR, 2.92) than did the patients with DM (OR, 2.13). Malignancy (OR, 2.62) and hypertension (OR, 1.86) were also significant risk factors for complications. However, smoking (OR, 0.83) was not significant. Poorly controlled DM remained associated with complications in multivariable logistic regression modeling (OR, 2.72). CONCLUSIONS: Poorly control DM defined by the preoperative HbA1c was significantly associated with postoperative complications. Smoking, however, was not so associated. Preoperative HbA1c can be used to assess the risk of postoperative spine surgery complications.

Hematocrit as a predictor of preoperative transfusion-associated complications in spine surgery: A NSQIP study.

BACKGROUND CONTEXT: Preoperative optimization of medical comorbidities prior to spinal surgery is becoming an increasingly important intervention in decreasing postoperative complications and ensuring a satisfactory postoperative course. The treatment of preoperative anemia is based on guidelines made by the American College of Cardiology (ACC), which recommends packed red blood cell transfusion when hematocrit is less than 21% in patients without cardiovascular disease and 24% in patients with cardiovascular disease. The literature has yet to quantify the risk profile associated with preoperative pRBC transfusion. PURPOSE: To determine the incidence of complications following preoperative pRBC transfusion in a cohort of patients undergoing spine surgery. STUDY DESIGN: Retrospective review of a national surgical database. PATIENT SAMPLE: The national surgical quality improvement program database OUTCOME NEASURES: Postoperative physiologic complications after a preoperative transfusion. Complications were defined as the occurrence of any DVT, PE, stroke, cardiac arrest, myocardial infarction, longer length of stay, need for mechanical ventilation greater than 48 h, surgical site infections, sepsis, urinary tract infections, pneumonia, or higher 30-day mortality. METHODS: The national surgical quality improvement program database was queried, and patients were included if they had any type of spine surgery and had a preoperative transfusion. RESULTS: Preoperative pRBC transfusion was found to be protective against complications when the hematocrit was less than 20% and associated with more complications when the hematocrit was higher than 20%. In patients with a hematocrit higher than 20%, pRBC transfusion was associated with longer lengths of stay, and higher rates of ventilator dependency greater than 48 h, pneumonia, and 30-day mortality. CONCLUSION: This is the first study to identify an inflection point in determining when a preoperative pRBC transfusion may be protective or may contribute to complications. Further studies are needed to be conducted to stratify by the prevalence of cardiovascular disease.

Postoperative Blood Salvage and Autotransfusion for Adult Spinal Deformity: A Randomized Controlled Trial.

STUDY DESIGN: Randomized controlled trial. OBJECTIVE: The aim of this study was to determine whether postoperative blood salvage and autotransfusion versus traditional closed suction drainage reduces the rate of homologous blood transfusions in patients undergoing surgery for adult spinal deformity. SUMMARY OF BACKGROUND DATA: The use of intraoperative blood salvage has become commonplace in spine surgery; however, the collection and reinfusion of blood drained from the wound postoperatively have not been employed routinely because of increased cost and questionable benefit. METHODS: Adult patients undergoing long posterior fusions were randomized to either a blood salvage and reinfusion system (OrthoPat - Group 1) or a standard subfascial closed suction drain (Group 2). Blood collected in Group 1 was reinfused according to the manufacturer's protocol. Reinfusion drains were converted to standard closed suction drains when output was <50 mL during 4 hours, and drains were removed when output was minimal. Patients received autologous or homologous blood transfusions when hemoglobin (Hg) <8 g/dL or they had symptomatic anemia. RESULTS: Thirty-four patients were randomized into Group 1 and 36 patients into Group 2. There were no differences in preoperative or intraoperative parameters. Patients in Group 1 had higher hemoglobin levels on postoperative day (POD) 2 and POD 3 compared to those in Group 2. However, there was no significant difference in the percentage of patients requiring homologous blood transfusion between the two groups (41% Group 1 vs. 60% Group 2, P = 0.17). Similarly a subgroup analysis in patients with estimated blood loss >2000 mL also showed no difference in homologous blood transfusion rates (67% Group 1 vs. 76% Group 2, P = 0.58). There were no differences in the rate or type of postoperative complications. CONCLUSION: Postoperative blood salvage and reinfusion result in a higher hemoglobin level in the early postoperative period, but does not significantly reduce the need for homologous blood transfusion. LEVEL OF EVIDENCE: 1.

A patient with extensive cerebral calcification due to pseudohypoparathyroidism: a case report.

BACKGROUND: Pseudohypoparathyroidism(PHP) is a heterogeneous group of disorders due to impaired activation of c AMP dependant pathways following binding of parathyroid hormone (PTH) to its receptor. In PHP end organ resistance to PTH results in hypocalcaemia, hyperphosphataemia and high PTH levels. CASE PRESENTATION: A 59 year old male presented with a history of progressive impairment of speech and unsteadiness of gait for 1 week and acute onset altered behavior for 1 day and one episode of generalized seizure. His muscle power was grade four according to MRC (medical research council) scale in all limbs and Chovstek's and Trousseau's signs were positive. Urgent non contrast computed tomography scan of the brain revealed extensive bilateral cerebral and cerebellar calcifications. A markedly low ionized calcium level of 0.5 mmol/l, an elevated phosphate level of 9.5 mg/dl (reference range: 2.7-4.5 mg/dl) and an elevated intact PTH of 76.3 pg/l were noted. His renal functions were normal. His hypocalcemia was accentuated by the presence of hypomagnesaemia. His 25 hydroxy vitamin D level was only marginally low which could not account for severe hypocalcaemia. A diagnosis of pseudohypoparathyroidism without phenotypic defects, was made due to hypocalcaemia and increased parathyroid hormone levels with cerebral calcifications. The patient was treated initially with parenteral calcium which was later converted to oral calcium supplements. His coexisting Vitamin D deficiency was corrected with 1αcholecalciferol escalating doses. His hypomagnesaemia was corrected with magnesium sulphate parenteral infusions initially and later with oral preparations. With treatment there was a significant clinical and biochemical response. CONCLUSION: Pseudohypoparathyroidism can present for the first time in elderly resulting in extensive cerebral calcifications. Identification and early correction of the deficit will result in both symptomatic and biochemical response.

First-4-week erythrocyte sedimentation rate variability predicts erythrocyte sedimentation rate trajectories and clinical course among patients with pyogenic vertebral osteomyelitis.

BACKGROUND: The trajectory pattern of erythrocyte sedimentation rate (ESR) in patients with pyogenic vertebral osteomyelitis (PVO) and its clinical significance is unclear. We further evaluated whether the first-4-week ESR variability can predict the trajectory pattern, treatment duration and recurrence of PVO. METHODS: The longitudinal ESR patterns of adults with PVO within the first 6 months were characterized through group-based trajectory modeling (GBTM). The ESR variability within the first 4 weeks was defined using the absolute difference (AD), coefficient of variation, percent change, and slope change. The first-4-week ESR variabilities were analyzed using ordinal logistic regression to predict the 6-month ESR trajectory and using logistic regression to predict treatment duration and recurrence likelihood. The discrimination and calibration of the prediction models were evaluated. RESULTS: Three ESR trajectory patterns were identified though GBTM among patients with PVO: Group 1, initial moderate high ESR with fast response; Group 2, initial high ESR with fast response; Group 3, initial high ESR with slow response. Group 3 patients (initial high ESR with slow response) were older, received longer antibiotic treatment, and had more comorbidities and higher recurrence rates than patients in the other two groups. The initial ESR value and ESR - AD could predict the 6-month ESR trajectory. By incorporating the first-4-week ESR variabilities and the clinical features of patients, our models exhibited moderate discrimination performance to predict prolonged treatment (≥12 weeks; C statistic, 0.75; 95% confidence interval [CI], 0.70 to 0.81) and recurrence (C statistic, 0.69; 95% CI, 0.61 to 0.78). CONCLUSIONS: The initial ESR value and first-4-week ESR variability are useful markers to predict the treatment duration and recurrence of PVO. Future studies should validate our findings in other populations.

The diagnostic value of soluble urokinase-type plasminogen activator receptor (suPAR) for the discrimination of vertebral osteomyelitis and degenerative diseases of the spine.

BACKGROUND: There is still a challenge in discriminating between vertebral osteomyelitis and degenerative diseases of the spine. To this end, we determined the suitability of soluble urokinase-type plasminogen activator receptor (suPAR) and compared the diagnostic potential of suPAR to CRP. METHODS: Patients underwent surgical stabilization of the lumbar and/or thoracic spine with removal of one or more affected intervertebral discs, as therapy for vertebral osteomyelitis (n = 16) or for erosive osteochondrosis (control group, n = 20). In this prospective study, we evaluated the suPAR and CRP levels before (pre-OP) and after surgery (post-OP) on days 3-5, 6-11, 40-56, and 63-142. RESULTS: The suPAR levels in vertebral osteomyelitis patients were significantly higher than those from controls pre-OP, 3-5 days post-OP, and 6-11 days post-OP. Significantly higher CRP levels were observed in the vertebral osteomyelitis group than in the controls pre-OP and 6-11 days post-OP. Levels of suPAR and CRP correlated positively in all patients in the pre-OP period: r = 0.63 (95% CI: 0.37-0.79), p < 0.0001. The values for the area under the receiver operating characteristics curve (AUC) for pre-OP and the overall model post-OP were 0.88 (95% CI: 0.76-1.00) and 0.84 (95% CI: 0.71-0.97) for suPAR, 0.93 (95% CI: 0.85-1.00) and 0.77 (95% CI: 0.62-0.93) for CRP, and 0.98 (95% CI: 0.96-1.00) and 0.91 (95% CI: 0.82-1.00) for the combination of suPAR and CRP. The AUC for suPAR pre-OP revealed an optimum cut-off value, sensitivity, specificity, NPV, and PPV of 2.96 ng/mL, 0.69, 1.00, 0.80, and 1.00, respectively. For CRP, these values were 11.58 mg/L, 0.88, 0.90, 0.90, and 0.88, respectively. CONCLUSION: The present results show that CRP is more sensitive than suPAR whereas suPAR is more specific than CRP. Moreso, our study demonstrated that improvement in the diagnostic power for discrimination of vertebral osteomyelitis and degenerative diseases of the spine can be achieved by a combination of both suPAR and CRP. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02554227, posted Sept. 18, 2015, and updated Aug. 13, 2019.

Procalcitonin and Neutrophil Lymphocyte Ratio After Spinal Instrumentation Surgery.

STUDY DESIGN: This was a retrospective observational study. OBJECTIVE: To assess the diagnostic value of procalcitonin (PCT) and neutrophil lymphocyte ratio (NLR) for predicting surgical site infection (SSI) in patients undergoing spinal instrumentation surgery, we analyzed a large consecutive cohort of patients who had undergone spinal instrumentation surgery. SUMMARY OF BACKGROUND DATA: Although PCT and NLR are commonly used as markers for bacterial infection, the diagnostic value of these factors for predicting SSI in the context of spinal instrumentation surgery has not been extensively investigated. METHODS: We retrospectively investigated 242 patients who underwent spinal instrumentation surgery and evaluated the significance of various postoperative measures for predicting SSI, including PCT and NLR. We then determined the diagnostic cut-off values for these markers in the prediction of SSI using receiver operating characteristic curve analysis. RESULTS: Among the 242 patients analyzed, 10 were diagnosed with infection. Even though univariate analysis showed that neutrophil percentage and NLR at 6 to 7 days postoperatively were significant predictors for SSI, PCT at 6 to 7 days postoperatively did not differ significantly between the SSI and non-SSI groups. The cut-off value used for neutrophil percentage at 6 to 7 days postoperatively was more than 69.0% [sensitivity, 80.0%; specificity, 70.0%; area under the curve, 0.737]. The cut-off value used for NLR at 6 to 7 days postoperatively was 3.87 (sensitivity, 70.0%; specificity, 73.2%; area under the curve, 0.688). CONCLUSION: Neutrophil percentage and NLR at 6 to 7 days postoperatively were more useful markers than PCT at 6 to 7 days postoperatively for early prediction of SSI in patients who had undergone spinal instrumentation surgery. Therefore, routine use of PCT as a predictor of postoperative infection is not supported by the results of this study. LEVEL OF EVIDENCE: 4.

Increased interleukin-6 and C-reactive protein levels after instrumented lumbar spine fusion in older patients.

PURPOSE: Interleukin 6 (IL-6) and the acute phase C-reactive protein (CRP) blood concentrations after lumbar spine fusion may be affected by age. The purpose of this prospective observational study was to assess postoperative serum levels of pro-inflammatory IL-6 and CRP after instrumented lumbar spine fusion surgery. We hypothesized that older patients would have increased levels of IL-6 and CRP after surgery. METHODS: IL-6 and high-sensitive CRP biochemical marker levels were measured before instrumented spinal fusion, and postoperatively at 1 and 3 days, 6 weeks, and 3 months. The 49 patients in this sample were divided into two groups: age ≤ 60 years ( n = 23) and age > 60 years ( n = 26). RESULTS: Acute changes in IL-6 high-sensitivity and CRP from preoperative levels to postoperative day (POD) 1 increased with age. Mean (95% CI) difference between the age-groups in changes of IL-6 at PODs 1 and 3 was 45 pg/ml (10-83, p = 0.014) and 20 pg/ml (5-36, p = 0.021), respectively. Mean (95% CI) difference between groups in changes of CRP at PODs 1 and 3 was 9.6 mg/l (-3.5 to 22.7, p = 0.47) and 24.8 mg/l (-17 to 67, p = 0.33), respectively. Both groups had decreased IL-6 and CRP levels at 6 weeks after surgery compared to the preoperative level. CONCLUSIONS: Elevation of IL-6 and CRP is stronger in patients over 60 years old after instrumented lumbar spinal fusion. The CRP and IL-6 are sensitive markers for acute postoperative inflammation. Even high acute CRP values do not necessarily indicate postoperative infection.

Preoperative Assessment of Bone Quality in Spine Deformity Surgery: Correlation With Clinical Practice and Published Recommendations.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The goals of this study were to (A) evaluate preoperative bone quality assessment and intervention practice over time and (B) review the current evidence for bone evaluation in spine fusion surgery. SUMMARY OF BACKGROUND DATA: Deformity spine surgery has demonstrated improved quality of life in patients; however, its cost has made it controversial. If preoperative bone quality can be optimized then potentially these treatments could be more durable; however, at present, no clinical practice guidelines have been published by professional spine surgical organizations. METHODS: A retrospective cohort review was performed on patients who underwent a minimum five-level primary or revision fusion. Preoperative bone quality metrics were evaluated over time from 2012 to 2017 to find potential trends. Subgroup analysis was conducted based on age, sex, preoperative diagnosis, and spine fusion region. RESULTS: Patient characteristics including preoperative rates of pseudarthrosis and junctional failure did not change. An increasing trend of physician bone health documentation was noted (P = 0.045) but changes in other metrics were not significant. A sex bias favored females who had higher rates of preoperative DXA studies (P = 0.001), Vitamin D 25-OH serum labs (P = 0.005), Vitamin D supplementation (P = 0.022), calcium supplementation (P < 0.001), antiresorptive therapy (P = 0.016), and surgeon clinical documentation of bone health (P = 0.008) compared with men. CONCLUSION: Our spine surgeons have increased documentation of bone health discussions but this has not affected bone quality interventions. A discrepancy exists favoring females over males in nearly all preoperative bone quality assessment metrics. Preoperative vitamin D level and BMD assessment should be considered in patients undergoing long fusion constructs; however, the data for bone anabolic and resorptive agents have less support. Clinical practice guidelines on preoperative bone quality assessment spine patients should be defined. LEVEL OF EVIDENCE: 4.

The endocannabinoid system in canine Steroid-Responsive Meningitis-Arteritis and Intraspinal Spirocercosis.

Endocannabinoids (ECs) are involved in immunomodulation, neuroprotection and control of inflammation in the central nervous system (CNS). Activation of cannabinoid type 2 receptors (CB2) is known to diminish the release of pro-inflammatory factors and enhance the secretion of anti-inflammatory cytokines. Furthermore, the endocannabinoid 2-arachidonoyl glycerol (2-AG) has been proved to induce the migration of eosinophils in a CB2 receptor-dependent manner in peripheral blood and activate neutrophils independent of CB activation in humans. The aim of the current study was to investigate the influence of the endocannabinoid system in two different CNS inflammatory diseases of the dog, i.e. Steroid-Responsive Meningitis-Arteritis (SRMA) and Intraspinal Spirocercosis (IS). The two main endocannabinoids, anandamide (AEA) and 2-AG, were quantified by mass spectrometry in CSF and serum samples of dogs affected with Steroid- Responsive Meningitis-Arteritis in the acute phase (SRMA A), SRMA under treatment with prednisolone (SRMA Tr), intraspinal Spirocercosis and healthy dogs. Moreover, expression of the CB2 receptor was evaluated in inflammatory lesions of SRMA and IS and compared to healthy controls using immunohistochemistry (IHC). Dogs with SRMA A showed significantly higher concentrations of total AG and AEA in serum in comparison to healthy controls and in CSF compared to SRMA Tr (p<0.05). Furthermore, dogs with IS displayed the highest ECs concentrations in CSF, being significantly higher than in CSF samples of dogs with SRMA A (p<0.05). CSF samples that demonstrated an eosinophilic pleocytosis had the highest levels of ECs, exceeding those with neutrophilic pleocytosis, suggesting that ECs have a major effect on migration of eosinophils in the CSF. Furthermore, CB2 receptor expression was found in glial cells in the spinal cord of healthy dogs, whereas in dogs with SRMA and IS, CB2 was strongly expressed not only in glial cells but also on the cellular surface of infiltrating leukocytes (i.e. neutrophils, eosinophils, lymphocytes, plasma cells, and macrophages) at lesion sites. The present study revealed an upregulated endocannabinoid system in dogs with inflammatory CNS diseases, highlighting the endocannabinoid system as a potential target for treatment of inflammatory CNS diseases.

Risk Factors for Surgical Site Infection After Posterior Lumbar Spinal Surgery.

STUDY DESIGN: A retrospective study. OBJECTIVE: The purpose of this study was to identify the independent risk factors for postoperative surgical site infection (SSI) after posterior lumbar spinal surgery based on the perioperative factors analysis. SUMMARY OF BACKGROUND DATA: SSI is one of the most common complications after spinal surgery. Previous studies have identified different risk factors for postoperative SSI after lumbar spinal surgery. However, most of the studies were focused on the patient and procedure-related factors. Few studies reported the correlation between laboratory tests and postoperative SSI. METHODS: A retrospective study was carried out in a single institution. Patients who underwent posterior lumbar spinal surgery between January 2010 and August 2016 were included in this study. All patients' medical records were reviewed and patients with postoperative SSI were identified. Perioperative variables were included to determine the risk factors for SSI by univariate and multivariate regression analysis. RESULTS: A total of 2715 patients undergoing posterior lumbar spinal surgery were included in this study. Of these patients, 64 (2.4%) were detected with postoperative SSI, including 46 men and 18 women. Diabetes mellitus (P = 0.026), low preoperative serum level of calcium (P = 0.009), low preoperative and postoperative albumin (P = 0.025 and 0.035), high preoperative serum glucose (P = 0.029), multiple fusion segments (P < 0.001), increased surgical time and estimated blood loss (P = 0.023 and 0.005), decreased postoperative hemoglobin (P = 0.008), and prolonged drainage duration (P = 0.016) were found to be the independent risk factors for SSI. Multilevel fusion and a history of diabetes mellitus were the two strongest risk factors (odds ratio = 2.329 and 2.227) for SSI. CONCLUSION: Based on a large population analysis, previous reported risk factors for SSI were confirmed in this study while some new independent risk factors were identified significantly associated with SSI following lumbar spinal surgery, including preoperative low serum level of calcium, decreased preoperative and postoperative albumin, and decreased postoperative hemoglobin. LEVEL OF EVIDENCE: 4.

Association between circulating miRNAs and spinal involvement in patients with axial spondyloarthritis.

OBJECTIVES: Dysregulation of miRNAs and their target genes contributes to the pathophysiology of autoimmune diseases. Circulating miRNAs may serve as diagnostic/prognostic biomarkers. We aimed to investigate the association between circulating miRNAs, disease activity and spinal involvement in patients with axial spondyloarthritis (AxSpA). METHODS: Total RNA was isolated from the plasma of patients with non-radiographic (nr)AxSpA, patients with ankylosing spondylitis (AS) and healthy controls (HC) via phenol-chloroform extraction. A total of 760 miRNAs were analysed with TaqMan® Low Density Arrays, and the expression of 21 miRNAs was assessed using single assays. RESULTS: Comprehensive analysis demonstrated the differential expression of miRNAs among patients with progressive spinal disease. Of the 21 miRNAs selected according to their expression patterns, the levels of miR-625-3p were significantly different between nr-AxSpA patients and HCs. We found no correlation between miRNA levels and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) in nr-AxSpA patients. Selected miRNAs, such as miR-29a-3p, miR-146a-5p or miR-222-3p with an established role in extracellular matrix formation and inflammation were associated with spinal changes and/or disease activity assessed by BASDAI in AS patients, including miR-625-3p reflecting disease activity in AS with spinal involvement. CONCLUSIONS: Our data indicate that circulating miRNAs play a role in the pathogenesis of AxSpA and are also suggestive of their potential as biomarkers of disease progression. We hypothesize that differential systemic levels of miRNA expression reflect miRNA dysregulation at sites of spinal inflammation or bone formation where these molecules contribute to the development of pathophysiological features typical of AxSpA.

Does preoperative oral carbohydrate treatment reduce the postoperative surgical stress response in lumbar disc surgery?

OBJECTIVES: Surgical trauma produces metabolic and hormonal responses, which are characterized by insulin resistance. Due to extension of the preoperative fasting period, which increases the magnitude of postoperative insulin resistance, preoperative oral carbohydrates (POC) have been developed. PATIENTS AND METHODS: This prospective, randomized, controlled study was performed on 43 ASA I-II patients undergoing elective microsurgical lumbar discectomy. The intervention group received oral carbohydrate solution 800mL the night before and 400mL 2h prior to operation. The other group fasted for 8h prior to operation. Blood samples were obtained the day before the operation, before induction of anesthesia, after skin incision, 1h, 2h, 6h and 24h following skin incision. Blood glucose, plasma insulin, cortisol and interleukin-6 (IL-6) levels were determined. The primary endpoint was to assess the effect of POC treatment on insulin resistance and surgical stress response following lumbar disc surgery. The secondary endpoint was to assess POC's effects on postoperative nausea and vomiting. RESULTS: The serum insulin levels were higher before induction of anesthesia in the study group and returned to fasted group levels by 2h after skin incision. The plasma IL-6 levels were higher in the intervention group at 6h after the skin incision. There were no differences between the two groups with respect to blood glucose, plasma cortisol levels and the incidence of nausea and vomiting. CONCLUSION: This study suggests that use of POC treatment does not attenuate development of insulin resistance in patients undergoing lumbar disc surgery.

Prospective controlled cohort study of Troponin I levels in patients undergoing elective spine surgery for degenerative conditions: Prone versus supine position.

Prior studies have suggested that elevated serum Troponin-I (TnI) levels immediately after non-cardiac surgical procedures (8-40%) represent subclinical cardiac stress which independently predicts increased 30-day mortality. Routine post-operative TnI monitoring has therefore been suggested as a standard of care. However, no prior studies have focussed on elective degenerative spine surgery, whilst few have measured pre-op TnI. Further, prolonged prone positioning could represent an additional, independent, cardiac stress. We planned a prospective controlled cohort study of consecutive TnI levels in routine elective spine surgery for degenerative spine conditions, incorporating 3 groups: 'prone<2h', 'prone>2h' and 'supine' positioning. TnI levels (>0.04µg/L) were recorded immediately pre-/post-surgery, and by 24h of surgery. N=120 patients were recruited. Complete results were obtained in 92 (39 supine, 53 prone). No significant between-groups differences were observed in demographic or cardiovascular risk factors. Validated TnI-elevation by 24h was not observed in any group. Spurious elevations were recorded in one 'prone<2h' and one 'prone>2h'. One non-ST segment myocardial infarction (STEMI) occurred on day 7 without TnI elevation by 24h (prone>2h). There was no 30-day mortality. CONCLUSIONS: Despite a lower cut-off, no validated TnI elevation was observed in any group by 24h after surgery. One non-STEMI had not been associated with TnI-elevation by 24h. Immediately peri-operative cardiac stress therefore appeared comparatively rare in patients undergoing routine elective spine surgery. Further, prone positioning did not represent an additional, independent, risk. Routine immediately post-operative TnI monitoring in elective spine surgery therefore appears unjustified. Our study highlighted several caveats regarding consecutive TnI testing.

The utility of obtaining routine hematological laboratory values following an anterior cervical diskectomy and fusion.

STUDY DESIGN: Retrospective analysis of a prospectively maintained database. OBJECTIVE: To characterize the utility of obtaining routine postoperative laboratory studies after an anterior cervical diskectomy and fusion (ACDF). SUMMARY OF BACKGROUND DATA: ACDF is typically associated with minimal blood loss and morbidity. However, at many institutions, postoperative laboratory studies are conducted routinely. This study aims to characterize the utility of these tests in the postoperative setting. METHODS: A retrospective analysis of a prospectively maintained database of 332 patients who underwent an ACDF for degenerative cervical spine disease between 2007 and 2014 was performed. Patients with a concurrent corpectomy, posterior fusion, or revision procedure were excluded. Patient demographics, comorbidities, visual analogue scale scores, surgical and hospitalization parameters, complications, and transfusion volumes were assessed. The patient's postoperative laboratory studies were compared with preoperative values. Statistical analysis was performed with independent sample T tests for continuous variables and χ analysis for categorical data. An α level of less than 0.05 denoted statistical significance. RESULTS: A total of 332 patients were included with a mean age of 51.1 ± 11.7 years. The overall mean procedural time, estimated blood loss, and length of stay were 60.0 ± 30.1 minutes, 69.4 ± 36.2 mL, and 40.2 ± 20.3 hours, respectively. Overall, 98.1% of patients demonstrated radiographical arthrodesis at 1 year. After a 1- or 2-level ACDF, the postoperative hemoglobin, hematocrit, blood urea nitrogen, sodium, and calcium levels significantly decreased, whereas glucose and chloride levels increased when compared with the preoperative values (P < 0.05). In addition, the 1-level ACDF cohort was also associated with reduced postoperative potassium level (P < 0.05). However, none of the patients required intraoperative or postoperative blood product transfusion or demonstrated evidence of postoperative anemia. Two patients (0.89%) required postoperative potassium replacement based upon laboratory values alone without clinical symptomatology. There were no complications that were related to the patient's hemodynamic status or fluid and electrolyte balance. CONCLUSION: In the majority of cases after an ACDF, no action was taken n the basis of the patient's routine postoperative laboratory data. None of the patients required blood product transfusion, whereas only 0.89% (n = 2) required potassium replacement for laboratory anomalies without clinical symptomatology. These findings suggest that routine postoperative complete blood counts do not change postoperative management after an ACDF unless intraoperative bleeding is noted or the patient carries risk factors for postoperative hemorrhagic anemia. LEVEL OF EVIDENCE: 3.

S100B, intraoperative neuromonitoring findings and their relation to clinical outcome in surgically treated intradural spinal lesions.

BACKGROUND: Neurophysiological monitoring (IOM) consisting of somatosensory (SEPs), muscle (MEPs) and spinal motor evoked (D-wave; spinal MEPs) potentials is used to indicate injury related to surgical treatment of intradural and intramedullary lesions. Combining spinal and muscle MEPs reliably predicts long-term motor deficit. If spinal MEPs recording is not possible, additional markers-e.g. S100B, a serum marker for glial injury-may be a helpful adjunct. Thus, serial serum S100B measurements were related to both the intraoperative IOM recordings and the long-term neurological outcome in patients surgically treated for cervical and thoracic intradural lesions. METHODS: In 33 patients (9 men, 24 women, 54 ± 17 years) during intramedullary (8) or intradural (25) cervical or thoracic spinal surgeries significant intraoperative SEP-amplitude decrement >50 % or MEP loss and serial S100B serum concentration (perioperative days 0, 1-3, 5) were related to outcome (>1 year after discharge, grouped into improved and unchanged/altered neurological symptoms). RESULTS: Differences in S100B levels between patients with improved and unchanged/altered neurological outcome were significantly on postoperative days 2 (0.085 ± 0.08 µg/l vs 0.206 ± 0.07 µg/l, p = 0.005) and 3 (0.076 ± 0.03 µg/l vs 0.12 ± 0.05 µg/l, p = 0.007). All patients with permanent altered neurological symptoms developed S100B levels >0.08 µg/l (0.09-0.35 µg/l). Eighty-one percent of patients with improved neurological symptoms presented with S100B levels ≤0.08 µg/l (0.02-0.08 µg/l). Nine out of ten patients (90 %) without changes in EP and S100B had an improved long-term outcome, whereas 9/13 patients (69 %) with changes in EP and S100B had altered neurological symptoms in long-term outcome. CONCLUSION: Intraoperative stable EPs and S100B ≤0.08 µg/l may be used as a marker to predict long-term neurological improvement, whereas EP-changes and elevated S100B levels on the 3rd postoperative day may be useful as a marker to predict long-term neurological alteration. In summary, the combined use of S100B and EPs might be helpful in the prediction of the severity of adverse spinal cord affection following surgery and guidance of patients.

High preoperative hemoglobin A1c is a risk factor for surgical site infection after posterior thoracic and lumbar spinal instrumentation surgery.

BACKGROUND: Diabetes mellitus (DM) is reported to be a risk factor for surgical site infection (SSI), which is a serious complication after spinal surgery. The effect of DM on SSI after instrumented spinal surgery remains to be clarified. The aim was to elucidate perioperative risk factors for infection at the surgical site after posterior thoracic and lumbar spinal arthrodesis with instrumentation in patients with DM. METHODS: Consecutive patients who underwent posterior instrumented thoracic and lumbar spinal arthrodesis during the years 2005-2011, who could be followed for at least 1 year after surgery, were included. These included 36 patients with DM (19 males and 17 females; mean age 64.3 years). The patients' medical records were retrospectively reviewed to determine the SSI rate. The characteristics of the DM patients were examined in detail, including the levels of serum glucose and HbA1c, which indicate the level of diabetes control. RESULTS: Patients with DM had a higher rate of SSI (6 of 36 patients, 16.7 %) than patients without DM (10 of 309 patients, 3.2 %). Although the perioperative serum glucose level did not differ between DM patients that did or did not develop SSI, the preoperative HbA1c value was significantly higher in the patients who developed SSI (7.6 %) than in those who did not (6.9 %). SSI developed in 0.0 % of the patients with controlled diabetes (HbA1c <7.0 %) and in 35.3 % of the patients with uncontrolled diabetes (HbA1c ≥7.0 %). CONCLUSIONS: DM patients whose blood glucose levels were poorly controlled before surgery were at high risk for SSI. To prevent SSI in DM patients, we recommend lowering the HbA1c to <7.0 % before performing surgery.

Interruption or deferral of antiretroviral therapy reduces markers of bone turnover compared with continuous therapy: The SMART body composition substudy.

Bone mineral density (BMD) declines significantly in HIV patients on antiretroviral therapy (ART). We compared the effects of intermittent versus continuous ART on markers of bone turnover in the Body Composition substudy of the Strategies for Management of AntiRetroviral Therapy (SMART) trial and determined whether early changes in markers predicted subsequent change in BMD. For 202 participants (median age 44 years, 17% female, 74% on ART) randomized to continuous or intermittent ART, plasma markers of inflammation and bone turnover were evaluated at baseline and months 4 and 12; BMD at the spine (dual-energy X-ray absorptiometry [DXA] and computed tomography) and hip (DXA) was evaluated annually. Compared with the continuous ART group, mean bone-specific alkaline phosphatase (bALP), osteocalcin, procollagen type 1 N-terminal propeptide (P1NP), N-terminal cross-linking telopeptide of type 1 collagen (NTX), and C-terminal cross-linking telopeptide of type 1 collagen (ßCTX) decreased significantly in the intermittent ART group, whereas RANKL and the RANKL:osteoprotegerin (OPG) ratio increased (all p ≤ 0.002 at month 4 and month 12). Increases in bALP, osteocalcin, P1NP, NTX, and ßCTX at month 4 predicted decrease in hip BMD at month 12, whereas increases in RANKL and the RANKL:OPG ratio at month 4 predicted increase in hip and spine BMD at month 12. This study has shown that compared with continuous ART, interruption of ART results in a reduction in markers of bone turnover and increase in BMD at hip and spine, and that early changes in markers of bone turnover predict BMD changes at 12 months.