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STUDY DESIGN.: Experimental, human cadaveric study. OBJECTIVE.: To assess the fixation effects of injecting cement augmentation before screw insertion or after insertion of fenestrated screws; the effect of modulating cement viscosity; and the effects of these techniques on screw removal. SUMMARY OF BACKGROUND DATA.: It seems clear that cement augmentation can enhance pedicle screw fixation in osteoporotic bone. What remains to be demonstrated is the aspects of optimal technique such that fixation is enhanced with the greatest safety profile. METHODS.: Part I: Human osteoporotic vertebrae were instrumented with solid (nonaugmented) screws, solid screws with polymethylmethacrylate (PMMA), partially cannulated fenestrated (Pfen) screws, or fully cannulated fenestrated (Ffen) screws through which PMMA was injected. Screw fixation was tested in pullout. Part II: Ffen screws were augmented with standard low-viscosity PMMA versus high-viscosity PMMA. Part III: Sample cohorts were extracted from vertebrae to assess required torque and characterize difficulty of extraction. RESULTS.: Part I: Pfen screws demonstrated the greatest fixation with mean failure force of 690 ± 182 N. All methods of cement augmentation demonstrated significant increases in screw fixation. Part II: Ffen screws did not demonstrate a significant difference in pullout strength when high-viscosity PMMA was used as compared with low-viscosity PMMA. Part III: Mean extraction torque values for solid augmented screws, Ffen screws, and Pfen screws were 1.167, 1.764, and 1.794 Nm, respectively, but these differences did not reach significance. None of the osteoporotic vertebrae sustained catastrophic failure during augmented screw extraction. CONCLUSION.: Polymethylmethacrylate cement augmentation clearly enhances pedicle screw fixation in osteoporotic vertebrae when tested in pure pullout. The technique used for cement injection and choice of specialty screws can have a significant impact on the magnitude of this effect. Fenestrated screws have the capacity to confine cement placement in the vertebral body and may provide enhanced safety from cement extrusion into the spinal canal. It is feasible to inject high-viscosity PMMA through this fenestration geometry, and higher-viscosity cement may enhance the fixation effect. [ABSTRACT FROM AUTHOR]

STUDY DESIGN.: Systematic review of literature focused on heterogeneity of treatment effect analysis. OBJECTIVE.: The objectives of this systematic review were to determine if comorbid disease and general health factors modify the effect of fusion versus nonoperative management in chronic low back pain (CLBP) patients? SUMMARY OF BACKGROUND DATA.: Surgical fusion as a treatment of back pain continues to be controversial due to inconsistent responses to treatment. The reasons for this are multifactorial but may include heterogeneity in the patient population and in surgeon's attitudes and approaches to this complex problem. There is a relative paucity of high quality publications from which to draw conclusions. We were interested in investigating the possibility of detecting treatment response differences comparing fusion to conservative management for CLBP among subpopulations with different disease specific and general health risk factors. METHODS.: A systematic search was conducted in MEDLINE and the Cochrane Collaboration Library for literature published from 1990 through December 2010. To evaluate whether the effects of CLBP treatment varied by disease or general health subgroups, we sought randomized controlled trials or nonrandomized observational studies with concurrent controls evaluating surgical fusion versus nonoperative management for CLBP. Of the original 127 citations identified, only 5 reported treatment effects (fusion vs. conservative management) separately by disease and general health subgroups of interest. Of those, only two focused on patients who had primarily back pain without spinal stenosis or spondylolisthesis. RESULTS.: Few studies comparing fusion to nonoperative management reported differences in outcome by specific disease or general health subpopulations. Among those that did, we observed the effect of fusion compared to nonoperative management was slightly more favorable in patients with no additional comorbidities compared with those with additional comorbidities and more marked in nonsmokers compared with smokers. CONCLUSION.: It is unclear from the literature which patients are the best candidates for fusion versus conservative management when experiencing CLBP without significant neurological impairment. Nonsmokers may be more likely to have a favorable surgical fusion outcome in CLBP patients. Comorbid disease presence has not been shown to definitively modify the effect of fusion. Further prospective studies that are designed to evaluate these and other subgroup effects are encouraged to confirm these findings. CLINICAL RECOMMENDATIONS.: We recommend optimizing the management of medical co-morbidities and smoking cessation before considering surgical fusion in CLBP patients. Strength of recommendation: Weak. [ABSTRACT FROM AUTHOR]

STUDY DESIGN: Retrospective review. OBJECTIVE: Our objective was to assess the short-term complication rate in patients undergoing treatment of thoracolumbar fixed sagittal plane deformity (FSPD). SUMMARY OF BACKGROUND DATA: The reported morbidity and mortality for the surgical treatment of thoracolumbar FSPD is varied and based on studies with small sample sizes. Further studies are needed to better assess FSPD complication rate, and the factors that influence it. METHODS: The Scoliosis Research Society (SRS) Morbidity and Mortality Database was queried to identify cases of thoracolumbar FSPD from 2004 to 2007. Complications were analyzed based on correction technique, surgical approach, surgeon experience (SRS membership status used as a surrogate), patient age, and history of prior surgery. RESULTS: Five hundred and seventy-eight cases of FSPD were identified. Osteotomies were performed in 402 cases (70%), including 215 pedicle subtraction osteotomies (PSO), 135 Smith-Petersen osteotomies (SPO), 19 anterior discectomy with corpectomy procedures (ADC), 18 vertebral column resections (VCR), and 15 unspecified osteotomies. There were 170 complications (29.4%) in 132 patients. There were three deaths (0.5%). The most common complications were durotomy (5.9%), wound infection (3.8%), new neurologic deficit (3.8%), implant failure (1.7%), wound hematoma (1.6%), epidural hematoma (1.4%), and pulmonary embolism (1.0%). Procedures including an osteotomy had a higher complication rate (34.8%) than cases not including an osteotomy (17.0%, P < 0.001), and this remained significant after adjusting for the effects of patient age, surgeon experience, and history of prior surgery (P = 0.003, odds ratio = 2.070, 95% CI = 1.291-3.321). Not significantly associated with complication rate were patient age (P = 0.68), surgeon experience (P = 0.18), and history of prior surgery (P = 0.10). Complication rates were progressively higher from no osteotomy (17.0%), to SPO (28.1%), to PSO (39.1%), to VCR (61.1%). CONCLUSION: The short-term complication rate for treatment of FSPD is 29.4%. The complication rate was significantly higher in patients undergoing osteotomies, and more aggressive osteotomies were associated with progressively higher complication rates. [ABSTRACT FROM AUTHOR]

STUDY DESIGN: Retrospective review of a prospectively collected database. OBJECTIVE: Our objective was to assess the rates of postoperative wound infection associated with spine surgery. SUMMARY OF BACKGROUND DATA: Although wound infection after spine surgery remains a common source of morbidity, estimates of its rates of occurrence remain relatively limited. The Scoliosis Research Society prospectively collects morbidity and mortality data from its members, including the occurrence of wound infection. METHODS: The Scoliosis Research Society morbidity and mortality database was queried for all reported spine surgery cases from 2004 to 2007. Cases were stratified based on factors including diagnosis, adult (>= 21 years) versus pediatric (<21 years), primary versus revision, use of implants, and whether a minimally invasive approach was used. Superficial, deep, and total infection rates were calculated. RESULTS.: In total, 108,419 cases were identified, with an overall total infection rate of 2.1% (superficial = 0.8%, deep = 1.3%). Based on primary diagnosis, total postoperative wound infection rate for adults ranged from 1.4% for degenerative disease to 4.2% for kyphosis. Postoperative wound infection rates for pediatric patients ranged from 0.9% for degenerative disease to 5.4% for kyphosis. Rate of infection was further stratified based on subtype of degenerative disease, type of scoliosis, and type of kyphosis for both adult and pediatric patients. Factors associated with increased rate of infection included revision surgery (P < 0.001), performance of spinal fusion (P < 0.001), and use of implants (P < 0.001). Compared with a traditional open approach, use of a minimally invasive approach was associated with a lower rate of infection for lumbar discectomy (0.4% vs. 1.1%; P < 0.001) and for transforaminal lumbar interbody fusion (1.3% vs. 2.9%; P = 0.005). CONCLUSION: Our data suggest that postsurgical infection, even among skilled spine surgeons, is an inherent potential complication. These data provide general benchmarks of infection rates as a basis for ongoing efforts to improve safety of care. [ABSTRACT FROM AUTHOR]

STUDY DESIGN: Retrospective analysis of prospectively collected database. OBJECTIVE: To analyze the rate of complications, including neurologic deficits, associated with operative treatment of pediatric isthmic and dysplastic spondylolisthesis. SUMMARY OF BACKGROUND DATA: Pediatric isthmic and dysplastic spondylolisthesis are relatively uncommon dis-orders. Several prior studies have suggested a high rate of complication associated with operative intervention. How-ever, most of these studies were performed with sufficiently small sample sizes such that the presence of one complication could significantly affect the overall rate. The Scoliosis Research Society (SRS) prospectively collects morbidity and mortality (M&M) data from its members. This multicentered, multisurgeon database permits analysis of the surgical treatment of this relatively rare condition on an aggregate scale and provides surgeons with useful information for preoperative counseling. METHODS: Patients who underwent surgical treatment for isthmic or dysplastic spondylolisthesis from 2004 to 2007 were identified from the SRS M&M database. Inclusion criteria for analysis included age <= 21 and a primary diagnosis of isthmic or dysplastic spondylolisthesis. RESULTS: Of 25,432 pediatric cases reported, there were a total of 605 (2.4%) cases of pediatric dysplastic (n 62, 10%) and isthmic (n 543, 90%) spondylolisthesis, with a mean age of 15 years (range, 4-21). Approximately 50% presented with neural element compression, and less than 1% of cases were revisions. Surgical procedures included fusions in 92%, osteotomies in 39%, and reductions in 38%. The overall complication rate was 10.4%. The most common complications included postoperative neurologic deficit (n 31, 5%), dural tear (n 8, 1.3%), and wound infection (n 12, 2%). Perioperative deep venous thrombosis and pulmonary embolus were reported in 2 (0.3%) and 1 (0.2%) patients, respectively. There were no deaths in this series. CONCLUSION: Pediatric isthmic and dysplastic spondylolisthesis are relatively uncommon disorders, representing only 2.4% of pediatric spine procedures in the present study. Even among experienced spine surgeons, surgical treatment of these spinal conditions is associated with a relatively high morbidity. [ABSTRACT FROM AUTHOR]

STUDY DESIGN: Retrospective review of a prospectively collected database. OBJECTIVE: The Scoliosis Research Society (SRS) collects morbidity and mortality (M and M) data from its members. Our objectives were to assess complication rates for 3 common spine procedures, compare these results with prior literature as a means of validating the database, and to assess rates of pulmonary embolism (PE) and deep venous thrombosis (DVT) in all cases reported to the SRS over 4 years. SUMMARY OF BACKGROUND DATA: Few modern series document complication rates of spinal surgery as routinely practiced across academic and community settings. Those available are typically based on relatively low numbers of procedures or confined to single-surgeon experiences. METHODS: The SRS M and M database was queried for lumbar microdiscectomy (LD), anterior cervical discectomy and fusion (ACDF), and lumbar stenosis decompression (LSD) cases from 2004 to 2007. Revisions were excluded. The database was also queried for occurrence of clinically evident PE and DVT in all cases from 2004 to 2007. RESULTS: A total of 9692 LDs, 6735 ACDFs, and 10,329 LSDs were identified, with overall complication rates of 3.6%, 2.4%, and 7.0%, respectively. These rates are comparable to previously published smaller series. For assessment of PE and DVT, 108,419 cases were identified and rates were calculated per 1000 cases based on diagnosis, age group, and implant use. Overall rates of PE, death due to PE, and DVT were 1.38, 0.34, and 1.18, respectively. Among 82,082 adults, the rate of PE ranged from 0.47 for LD to 12.4 for metastatic tumor. Similar variations were noted for DVT and deaths due to PE. CONCLUSION: Overall major complication rates for LD, ACDF, and LSD based on the SRS M and M database are comparable to those in previously reported smaller series, supporting the validity of this database for study of other less common spinal disorders. In addition, our data provide general benchmarks of clinically evident PE and DVT rates as a basis for ongoing efforts to improve care. [ABSTRACT FROM AUTHOR]

STUDY DESIGN: Case report. OBJECTIVE: To discuss the spinal presentation and treatment of paraganglioma, a rare tumor of the extra-adrenal paraganglia, derived from neural crest cells in sympathetic ganglions. SUMMARY OF BACKGROUND DATA: Malignant paragangliomas are a very rare entity. The diagnosis of malignant paraganglioma is made by local recurrence after total resection of the primary mass, or findings of distant metastases. Roughly half of distant metastases are located in the cervical lymph nodes, and the remainder is evenly distributed among bone, lung, and liver. Vertebral metastases are exceedingly rare, and only isolated case reports have described them. METHODS: A 71-year-old man reported increasing neck pain and upper extremity weakness. The patient had a previous carotid body tumor resection in the past and a contralateral carotid body tumor left intact. Our imaging workup, including plain radiograph, computerized tomography scan and MRI, revealed an intraosseous lesion at C6 with vertebral body destruction. The patient underwent decompressive surgery through an anterior Smith-Robinson approach for myelopathy, followed by adjuvant external beam radiation. The histologic and immunohistochemical assays revealed a malignant paraganglioma. RESULTS: Paragangliomas are often highly vascular tumors. Intraoperative blood loss was significant and may have been mitigated by preoperative embolization. The patient showed clinical improvement almost immediately after surgery. CONCLUSION: We report a rare case of malignant paraganglioma and discussed adjuvant treatments to consider for distant metastases, such as I-MIBG, conventional radiotherapy, and chemotherapy. [ABSTRACT FROM AUTHOR]