Post-operative infection is a serious complication of spine surgery and can contribute to the strain on the healthcare system's resources. The purpose of this study is to determine what factors affect the risk of developing postoperative infection. We hypothesize that female gender, smoking, diabetes, having thoracolumbar procedures, having a neurological deficit, increased age, body mass index (BMI), American Society of Anaesthesiologists (ASA) score, blood loss, number of operative levels, operative time and undergoing non-elective surgery will increase the patients' risk of developing a post-operative infection.

A retrospective review of prospectively collected data within the Canadian Spine Outcome and Research Network (CSORN) was conducted. Data was analyzed using IBM-SPSS. Multivariable logistical regression analysis was conducted (odds ratios) to determine any association between the outcome and independent factors. Significance level was p < 0.05.

There were 7747 patients identified from the registry that had completed at least 12 weeks of follow up. There were 199 infections recorded representing a 2.6% risk of infection. There were no association found between the risk of developing a post operative infection and gender, smoking, diabetes, having thoracolumbar procedures, having a neurological deficit, ASA score, blood loss, number of operative levels and undergoing non-elective surgery. The following were associated with an increased risk of developing a post operative infection: Older age (adjusted OR=1.021, 95% CI=1.005–1.038, p < 0 .05), having an elevated BMI (adjusted OR=1.042, 95% CI=1.013–1.072, p < 0 .005), longer operative time (adjusted OR=1.002, 95% CI=1.001–1.004, p < 0 .001).

There is a 2.6% overall rate of post-operative spine infection across 20 Canadian centres. The factors that were associated with an increased risk of developing a post operative-infection were older age, increased BMI and longer operative time. This study establishes a benchmark against which the effectiveness of future interventions to reduce infection can be compared.

Purpose: The decision of whether or not an injury to the sub-axial cervical spine needs operative management often hinges on the stability of the spine. The posterior Ligamentous Complex (PLC) is one of the primary soft tissue stabilizers of the cervical spine. Fat-saturated T2-wieghted MRI sequences are able to demonstrate soft tissue injury to the cervical spine. No studies to date have assessed the ability of MRI to accurately and reliably demonstrate PLC disruption in the sub-axial cervical spine.

Method: Forty-nine consecutive patients aged 14–85 years presenting to the two participating institutions with injury between C3 and T1 who required posterior surgery as part of their management were prospectively enrolled in the study. All patients had radiographs, CT, and MRI scans preoperatively, which were reviewed by a Neuroradiologist, and the treating surgeon separately. Their posterior intraoperative findings were then recorded by the treating surgeon and his assistant. Statistical analysis included Spearman’s rank order correlation, and Cohen’s kappa score.

Results: There was a moderate level of agreement between the radiologist’s interpretation of the preopera-tive MRI and the surgeon’s intraoperative findings for the supraspinous and intraspinous ligaments, (kappa.49 & .48 respectively). A fair level of agreement was found for the ligamentum flavum, left and right facet capsules, and the cervical fascia (kappa scores.31,.30,.30,.39 respectively).

Conclusion: MRI has a high sensitivity (78.6% to 100%) for detecting cervical PLC injury but a low specificity (53.6% to 75%). On its own MRI is not a useful tool for diagnosing cervical spine PLC injury. The clinician should be aware of the relatively high rate of false positive PLC injury diagnosis with MRI.

Purpose: Apoptosis of osteoblasts and osteoclasts regulates bone homeostasis. Vertebral osteoporotic insufficiency fractures are characterised by pathological rates of osteoblast apoptosis. Skeletal injury in humans results in ‘angiogenic’ responses primarily mediated by vascular endothelial growth factor(VEGF), a protein essential for bone repair in animal models. Osteoblasts release VEGF in response to a number of stimuli and express receptors for VEGF in a differentiation dependent manner. This study investigates the putative role of VEGF in regulating the lifespan of primary human vertebral osteoblasts (PHVO) in-vitro.

Method: PHVO were cultured from biopsies taken at time of therapeutic vertebroplasty and were examined for VEGF receptors. Cultures were supplemented with VEGF(0–50ng/mL), a neutralising antibody to VEGF, mAB VEGF(0.3ug/mL) and Placental Growth Factor (PlGF), an Flt-1 receptor-specific VEGF ligand(0–100 ng/mL) to examine their effects on mineralised nodule assay, alkaline phosphatase assay and apoptosis. The role of the VEGF specific antiapoptotic gene target BCl2 in apoptosis was determined.

Results: PHVO expressed functional VEGF receptors. VEGF 10 and 25 ng/mL increased nodule formation 2.3- and 3.16-fold and alkaline phosphatase release 2.6 and 4.1-fold respectively while 0.3ug/mL of mAB VEGF resulted in approx 40% reductions in both. PlGF 50ng/mL had greater effects on alkaline phosphatase release (103% increase) than on nodule formation (57% increase). 10ng/mL of VEGF inhibited spontaneous and pathological apoptosis by 83.6% and 71% respectively, while PlGF had no significant effect. Pretreatment with mAB VEGF, in the absence of exogenous VEGF resulted in a significant increase in apoptosis (14 versus 3%). BCl2 transfection gave a 0.9% apoptotic rate. VEGF 10 ng/mL increased BCl2 expression four fold while mAB VEGF decreased it by over 50%.

Conclusion: VEGF is a potent regulator of osteoblast life-span in-vitro. This autocrine feedback regulates survival of these cells, mediated via the KDR receptor and expression of BCl2 antiapoptotic gene. This mechanism may represent a novel therapeutic model for the treatment of osteoporosis.

Purpose: To determine whether neural axis level of injury (SCI, CMI, or CEI) is related to motor improvement, as defined by the International Standards for Neurological Classification of Spinal Cord Injury motor score (MS), in patients with a thoracolumbar (T11-L3) spine injury.

Method: Fifty-three patients who sustained a neurological deficit secondary to a thoracolumbar spinal injury between 1995–2003 had injury details and MS collected prospectively. An independent evaluation determined the follow-up MS and SF-36 generic health-related quality of life (HrQOL) at a mean of 6.6 (SD 2.5) years post-injury. All patients had an MRI reviewed by a spine surgeon and neuroradiologist to determine the location of their conus medullaris and precise level of neural axis injury.

Results: Nineteen patients (37%) had SCI, 20 (39%) had CMI, and 12 (24%) had CEI, while two could not be classified. Patients with SCI improved their MS by an average 7.0 motor points (SD 9.8); CMI improved 11.9 (SD 11.8); and CEI improved 16.8 (SD 16.0). This trend did not achieve statistical significance (p=0.09). Multivariate analyses demonstrated that initial MS had a significant interaction with neural axis level of injury with respect to the primary outcome. Specifically, CEI showed the greatest improvement in MS only when the initial MS was less than 75. Absence of initial anal sensation, a fracture-dislocation injury type and increasing time to surgery were all statistically associated with less improvement in MS. The mean follow-up SF-36 physical component score (PCS) was 37.3 (SD 10.1) and the mean mental component score (MCS) was 51.4 (SD 11.8). There was no significant difference in mean PCS and MCS for varying levels of neural axis injury.

Conclusion: Patients with a CEI demonstrated the most improvement in MS, while absent anal sensation, a fracture-dislocation, and long delay to surgery were poor prognostic indicators for motor recovery. The HrQOL outcomes did not vary with neural axis level of injury. The results of this study assist in determining a prognosis for patients that sustain these common injuries. Future research should focus on how specific pre- and peri-operative variables affect outcomes in patients with neurological deficits secondary to thoracolumbar injuries.

Purpose: To evaluate the demographics, presentation, treatment and outcomes of spinal infection in a population of Intravenous Drug Users.

Method: Data on all patients with pyogenic spinal infection presenting to a quaternary referral center was obtained from a prospectively maintain database.

Results: Over the five-year study period, there were 102 patients treated for Primary Pyogenic Infection of the Spine of which 51 were Intravenous Drug Users (IVDU). Of this IVDU group there were 34 males. Mean age was 43 years (range 25 – 57). Twenty-three had HIV, 43 Hepatitis C and 13 Hepatitis B. All were using cocaine, 26 were also using Heroin and 44 more than three recreational drugs. Thirty patients presented with axial pain with a mean duration of 51 days (range 3–120). Thirty-one were ASIA D or worse with eight ASIA A. Mean Motor Score of patients with deficit was 58.6. Most common ASIA Motor Levels were C4 and C5. Mean duration of neurological symptoms was seven days (range 1–60). Blood parameters on admission were in keeping with sepsis in immunocompromised patients. None had previous surgery for spinal infection. Twenty-sex were receiving IV antibiotics for known spinal infection. 44 patients were treated surgically. 32 had infection of the cervical spine, 9 Thoracic and 3 Lumbar. 22 had a posterior approach alone, 13 had anterior only while 9 required combined. Mean operative time was 263 mins (range 62 – 742). 13 required tracheostomy. 7 required early revision for hardware failure and 2 for surgical wound infection. Mean duration of antibiotic treatment was 49 days (range 28–116). 26 patients had single agent therapy. 17 had MSSA and 17 MRSA. At discharge 28 patients had neurological improvement (mean 20 ASIA points, range 1–55), 11 had deterioration (mean 13, range 1–50) and 5 were unchanged. There were no in-hospital deaths. At 2 years after index admission 13 patients were dead and none were attending the unit for follow-up.

Conclusion: Primary pyogenic spinal infection in IVDU’s typically presents with sepsis and acute cervical quadriplegia. Surgical management must be prompt and aggressive with significant neurological improvement expected in the majority of patients.

Purpose: Oncologic management of primary bone tumors of the spine is inconsistent, controversial and open to individual interpretation. Tumor margin violation intraoperatively increases local recurrence and mortality. The purpose of this study is to determine whether applying Enneking’s principles to the surgical management of primary bone tumors of the spine significantly decreases local recurrence and/or mortality.

Method: A prospective and retrospective multicenter Cohort Study: Inclusion of patients undergoing en bloc or intralesional resection of primary tumors of the spine at four separate quaternary care centers, between January 1994 and January 2008. Patients were staged, using the Enneking system, prior to surgery and baseline demographic and surgical variables were recorded. Outcomes measured were disease local recurrence, or death. The results were statistically analyzed for significance.

Results: One hundred-fifty patients with primary tumors of the spine were recruited. Average age was 47.0 (range 8 to 83). Sixty-two patients were identified to have local recurrence. A statistically significant decrease in local recurrence (p=0.0001) was observed in favor of en bloc resection. In patients with local recurrence there was a significant increased risk of mortality, (p< 0.0001). There was a trend to decreased mortality in the en bloc resection group, not statistically significant (p=0.64).

Conclusion: Wide resection of primary tumors of spine with reconstruction is the standard of care. Application of Enneking’s principles to the spine when managing primary bone tumors significantly reduces local recurrence of the disease process, without an adverse outcome on mortality, and with acceptable HRQOL. Further cohort studies based on stringent data collection prospectively will provide a basis for more detailed study of individual tumor types.