Faculty Bibliography

BACKGROUND CONTEXT: Recent reports have implicated high rates of specific complications associated with bone morphogenetic protein (BMP) use. Little data exists comparing the rates and timing of specific postoperative complications for adult spinal deformity (ASD) patients treated with and without BMP. PURPOSE: Compare the complication profiles for BMP vs no BMP use in ASD. STUDY DESIGN/SETTING: Multicenter, prospective, consecutive case/ control series. PATIENT SAMPLE: 261 ASD patients consecutively enrolled into a prospective, multicenter database. OUTCOME MEASURES: Complications including: total, major and minor complications; superficial and deep infections; neurological, operative, radiographic, implant cardiovascular, renal and gastrointestinal complications; and complications requiring surgery. METHODS: Multicenter, prospective analysis of postoperative complications for consecutive ASD patients receiving BMP (BMP) or no BMP (NOBMP). BMP evaluated by location of use: posterior only (PBMP), interbody + posterior (I+PBMP). Inclusion criteria: age >=18 years, fusion >=4 levels, complete demographic, radiographic and operative data, and minimum 1-year follow up. ASD5scoliosis <=20degree, sagittal vertical axis (SVA) >=5cm, pelvic tilt (PT) >=25degree or thoracic kyphosis (TK) > 60degree). Specific complications evaluated. Time frames for postoperative complications included: operative =0 months, 0-3 months, 3-12 months, > 12 months. RESULTS: 261 consecutive patients (mean follow up 30.3 months; range 12.2-47.9) met inclusion criteria; PBMP (n=93), I+PBMP (n=58), NOBMP (n=103). Mean BMP dosing: posterior=2.5 mg/level, interbody=5 mg/level. Total PSF levels were similar for all groups (PBMP=12.2, I+PBMP=11.9, NOBMP=12.1). I+PBMP was older (63 vs 57 years), had greater Charlson comorbidity index (2.1 vs 1.2), longer OR time (514 vs 415 minutes) and greater EBL (2.8L vs 1.8L) than NOBMP, respectively (p<0.05). At 0-3 months, NOBMP had fewer total (0.6 vs 1.4 vs 1.4) and minor (0.2 vs 1.0 vs 0.7)!

BACKGROUND CONTEXT: Spine deformity surgery usually involves substantial blood loss. The antifibrinolytics tranexamic acid (TXA) and aminocaproic acid (EACA) have been shown to improve hemostasis in large blood loss surgeries. This study aimed to provide high-quality evidence regarding the relative efficacies of TXA, EACA and placebo in reducing blood loss and transfusion requirements in spine surgery. PURPOSE: To compare efficacies of TXA, EACA and placebo in patients undergoing posterior spinal fusion. STUDY DESIGN/SETTING: Prospective, double-blinded, randomized controlled trial. PATIENT SAMPLE: Patients (ages 18-80) undergoing posterior spinal fusion of at least five levels for correction of adult spinal deformity (AD) were enrolled. Patients with evidence of renal dysfunction, religious or other beliefs prohibiting transfusions, anti-coagulant use or abnormal baseline coagulation panels, or a medical history precluding use of TXA or EACA were excluded. OUTCOME MEASURES: Primary outcome measures included intraoperative, total blood loss (TBL) and transfusion rates. Secondary outcomes included change in hematocrit (Hct) and complications. METHODS: This is a prospective, randomized, double-blinded comparison of TXA, EACA and placebo used intra-operatively in patients with AD. Fifty-two patients were randomized to one of three treatment groups. TXA was given intravenously at 10 mg/kg loading dose followed by 1mg/ kg/h maintenance, while EACA was given at 100mg/kg loading dose followed by 10 mg/kg/h maintenance. Dosage calculation was based on previous studies and the rationale that TXA is 10 times more potent than EACA. Primary and secondary outcome measures were recorded as described above. ANOVA and Fisher's PLSD tests were used to compare continuous data and Fisher's exact test was used for categorical data. TBL was the sum of intraoperative blood loss and postoperative drain output. RESULTS: AD patients received TXA (n=19), EACA (n=19) or placebo (n=14) in the operating room (mean ages 60,!

Object Lateral mass screws (LMS) have been used extensively with a low complication rate in the subaxial spine. Recently, cervical pedicle screws (CPS) have been introduced, and are thought to provide more optimal stabilization of the subaxial spine in certain circumstances. However, because of the concern for neurovascular injury, the routine use of CPS in this location remains controversial. Despite this controversy, however, there are no articles directly comparing screw-related complications of each procedure in the subaxial cervical spine. The purpose of this study was to evaluate screw-related complications of LMS and CPS in the subaxial cervical spine. Methods A PubMed/MEDLINE and Cochrane Collaboration Library search was executed, using the key words "lateral mass screw" and "cervical pedicle screw." Clinical studies evaluating surgical procedures of the subaxial cervical spine in which either LMS or CPS were used and complications were reported were included. Studies in which the number of patients who had subaxial cervical spine surgery and the number of screws placed from C-3 to C-7 could not be specified were excluded. Data on screw-related complications of each study were recorded and compared. Results Ten studies of LMS and 12 studies of CPS were included in the analysis. Vertebral artery injuries were slightly but statistically significantly higher with the use of CPS relative to LMS in the subaxial cervical spine. Although the use of LMS was associated with a higher rate of screw loosening, screw pullout, loss of reduction, pseudarthrosis, and revision surgery, this finding was not statistically significant. Conclusions Based on the available literature, it appears that perioperative neurological and late biomechanical complication rates, including pseudarthrosis, are similarly low for both LMS and CPS techniques. In contrast, vertebral artery injuries, although statistically significantly more common when using CPS, are extremely rare with both techniques, which may justify their nonroutine use in select cases. Given the paucity of well-designed studies available, this recommendation may be a reflection of deficiencies in the available studies. Surgeons using either technique should have intimate knowledge of cervical anatomy and an adequate preoperative evaluation for each patient, with the final selection based on individual case requirements and anatomical limitations.

STUDY DESIGN: Retrospective review. OBJECTIVE: To analyze the trends in complications and mortality after spinal fusions. SUMMARY OF BACKGROUND DATA: Utilization of spinal fusions has been increasing during the past decade. It is essential to evaluate surgical outcomes to better identify patients who benefit most from surgical intervention. Integration of empiric evidence from large administrative databases into clinical decision making is instrumental in providing higher-quality, evidence-based, patient-centered care. METHODS: This study used Nationwide Inpatient Sample data from 2001 through 2010. Patients who underwent spinal fusions were identified using the CCS (Clinical Classifications Software) and ICD-9 (International Classification of Diseases, 9th Revision) codes. Data on patient comorbidities, primary diagnosis, and postoperative complications were obtained via ICD-9 diagnosis codes and via CCS categories. National estimates were calculated using weights provided as part of the database. Time trend analysis for average length of stay, total charges, mortality, and comorbidity burden was performed. Univariate and multivariate models were constructed to identify predictors of mortality and postoperative complications. RESULTS: An estimated 3,552,873 spinal fusions were performed in the United States between 2001 and 2010. The national bill for spinal fusions increased from $10 billion to $46.8 billion. Today, patients are older and have a greater comorbidity burden than 10 years ago. Mortality remained relatively constant at 0.46%, 1.2%, and 0.14% for cervical, thoracic, and lumbar fusions, respectively. Morbidity rates showed an increasing trend at all levels. Multivariate analysis of 19 procedures and patient-related risk factors and 9 perioperative complications identified 85 statistically significant (P< 0.01) interactions. CONCLUSION: The data on perioperative risks and risk factors for postoperative complications of spinal fusions presented in this study is pivotal to appropriate surgical patient selection and well-informed risk-benefit evaluation of surgical intervention.Level of Evidence: N/A.

Object Posterolateral spinal fusion (PSF) has long been the standard of care for degenerative spondylolisthesis, but less invasive, motion-preserving alternatives have been proposed to reduce the complications associated with fusion while still providing neural decompression and stabilization. The object of the current study is to evaluate the safety and efficacy of coflex Interlaminar Stabilization compared with PSF to treat low-grade spondylolisthesis with spinal stenosis. Methods This is a prospective, randomized, multicenter FDA investigational device exemption (IDE) trial comparing coflex Interlaminar Stabilization with laminectomy and PSF. A total of 322 patients from 21 sites in the US were enrolled between 2006 and 2008 for the IDE trial. The current study evaluated only the subset of patients from this overall cohort with Grade 1 spondylolisthesis (99 in the coflex group and 51 in the fusion group). Subjects were randomized 2:1 to receive decompression and coflex interlaminar stabilization or decompression and posterolateral spinal fusion with spinal instrumentation. Data collected included perioperative outcomes, Oswestry Disability Index (ODI), back and worse leg visual analog scale (VAS) scores, 12-Item Short Form Health Survey, Zurich Claudication Questionnaire (ZCQ), and radiographic outcomes at a minimum of 2 years. The FDA criteria for overall device success required the following to be met: 15-point reduction in ODI, no reoperations, no major device-related complications, and no postoperative epidural injections. Results At a minimum of 2 years, patient follow-up was 94.9% and 94.1% in the coflex and fusion control groups, respectively. There were no group differences at baseline for any demographic, clinical, or radiographic parameter. The average age was 63 years in the coflex cohort and 65 years in the fusion cohort. Coflex subjects experienced significantly shorter operative times (p < 0.0001), less estimated blood loss (p < 0.0001), and shorter length of stay (p < 0.0001) than fusion controls. Both groups experienced significant improvements from baseline at 2 years in ODI, VAS back, VAS leg, and ZCQ, with no significant group differences, with the exception of significantly greater ZCQ satisfaction with coflex at 2 years. FDA overall success was achieved in 62.8% of coflex subjects (59 of 94) and 62.5% of fusion controls (30 of 48) (p = 1.000). The reoperation rate was higher in the coflex cohort (14 [14.1%] of 99) compared with fusion (3 [5.9%] of 51, p = 0.18), although this difference was not statistically significant. Fusion was associated with significantly greater angulation and translation at the superior and inferior adjacent levels compared with baseline, while coflex showed no significant radiographic changes at the operative or index levels. Conclusions Low-grade spondylolisthesis was effectively stabilized by coflex and led to similar clinical outcomes, with improved perioperative outcomes, compared with PSF at 2 years. Reoperation rates, however, were higher in the coflex cohort. Patients in the fusion cohort experienced significantly increased superior and inferior level angulation and translation, while those in the coflex cohort experienced no significant adjacent or index level radiographic changes from baseline. Coflex Interlaminar Stabilization is a less invasive, safe, and equally efficacious clinical solution to PSF to treat low-grade spondylolisthesis, and it appears to reduce stresses at the adjacent levels. Clinical trial registration no.: NCT00534235 ( ClinicalTrials.gov ).

STUDY DESIGN: Prospective, randomized, multicenter, Food and Drug Administration Investigational Device Exemption trial. OBJECTIVE: To evaluate the safety and efficacy of Coflex interlaminar stabilization compared with posterior spinal fusion in the treatment of 1- and 2-level spinal stenosis and degenerative spondylolisthesis. SUMMARY OF BACKGROUND DATA: Long-term untoward sequelae of lumbar fusion for stenosis and degenerative spondylolisthesis have led to the search for motion-preserving, less-invasive alternatives. METHODS: Three hundred twenty-two patients (215 Coflex and 107 fusions) from 21 sites in the United States were enrolled between 2006 and 2010. Subjects were randomized to receive laminectomy and Coflex interlaminar stabilization or laminectomy and posterolateral spinal fusion with spinal instrumentation in a 2:1 ratio. Overall device success required a 15-point reduction in Oswestry Disability Index, no reoperations, no major device-related complications, and no postoperative epidural injections. RESULTS: Patient follow-up at minimum 2 years was 95.3% and 97.2% in the Coflex and fusion control groups, respectively. Patients taking Coflex experienced significantly shorter operative times (P < 0.0001), blood loss (P < 0.0001), and length of stay (P < 0.0001). There was a trend toward greater improvement in mean Oswestry Disability Index scores in the Coflex cohort (P = 0.075). Both groups demonstrated significant improvement from baseline in all visual analogue scale back and leg parameters. Patients taking Coflex experienced greater improvement in Short-Form 12 physical health outcomes (P = 0.050) and equivalent mental health outcomes. Coflex subjects experienced significant improvement in all Zurich Claudication Questionnaire outcomes measures compared with fusion (symptom severity [P = 0.023]; physical function [P = 0.008]; satisfaction [P = 0.006]). Based on the Food and Drug Administration composite for overall success, 66.2% of Coflex and 57.7% of fusions succeeded (P = 0.999), thus demonstrating noninferiority. The overall adverse event rate was similar between the groups, but Coflex had a higher reoperation rate (10.7% vs. 7.5%, P = 0.426). At 2 years, fusions exhibited increased angulation (P = 0.002) and a trend toward increased translation (P = 0.083) at the superior adjacent level, whereas Coflex maintained normal operative and adjacent level motion. CONCLUSION: Coflex interlaminar stabilization is a safe and efficacious alternative, with certain advantages compared with lumbar spinal fusion in the treatment of spinal stenosis and low-grade spondylolisthesis.Level of Evidence: 1.

Study Design. Retrospective review of prospectively collected surgical dataObjective. This study sought to determine the effect of fellow education over the course of the academic year (August - July) on surgical outcomes in adolescent idiopathic scoliosis (AIS). One surgeon and one type of surgery were chosen to minimize confounding factors.Summary of Background Data. Educating and training the next generation of physicians and surgeons is necessary for the survival and continuation of medical care. There has been recent momentum to scientifically document that medical education is safe. Spine surgery is complex and demanding, with a steep learning curve making it an ideal model to detect any potential negative impact of medical education.Methods. Subjects: adolescent patients undergoing posterior spinal surgery, between August 2007-July 2010, by a single senior surgeon at one institution with a fellow as the only surgical assistant. Demographic and perioperative data were collected then segmented by surgical date into quarters according to the rotations of the academic year. One fellow was included in each quarter over four years, resulting in 16 fellows across the four quarters. An ANOVA was used to assess differences in operative time, blood loss, length of stay and complications between the quarters of the year.Results. There were no significant differences between the groups regarding age, sex, or Lenke curve type. No statistically significant differences were found between the four quarters of the fellowship year for estimated blood loss, use of cell saver, length of stay, operative time, and complication rate.Conclusions. This study is the first to show that fellow education over the course of the academic year did not impact the patient outcomes studied. It is clear that while there is significant academic benefit for the fellows as they complete their spine fellowship, there is no negative impact for patients.

BACKGROUND CONTEXT: Although lumbar interbody fusion has long been a common procedure in the practice of spine surgery, focus on the technological development has produced the relatively new procedure of transforaminal lumbar interbody fusion (TLIF). This procedure is often available to surgeons as an alternative to anterior-posterior circumferential fusion (AP fusion), and both procedures have been demonstrated to be clinically equivalent at up to 5 years after surgery. In the context of clinical equipoise, it is unknown which procedure is more economically advantageous. PURPOSE: To compare the hospital costs, charges, and payments received for surgical treatment with either AP fusion or TLIF. Future directions for health economic research with respect to spine surgery are also considered and discussed. STUDY DESIGN: This is an institutional review board-approved, single-institution retrospective chart review and cost analysis. PATIENT SAMPLE: Our study included patients undergoing either single-level AP fusion or single-level TLIF between 2006 and 2008. All patients were older than 18 years at the time of surgery; the decision of which procedure was performed was entirely at the discretion of the attending surgeon. OUTCOME MEASURES: Hospital costs, charges, and payments received for the treatment of each patient. METHODS: We performed a retrospective review of the medical and financial records of patients undergoing either AP fusion (n=179) or TLIF (n=90) on one operative level between 2006 and 2008. Medical records were evaluated for a history of spine surgery, operative time, estimated blood loss, and length of stay, whereas financial records were reviewed for the hospital costs, charges, and payments received as recorded by the hospital accounting data. Operative materials and service charges were also isolated and compared separately. This study was departmentally sponsored; there were no interest-associated biases for any of the authors involved. RESULTS: AP fusion patients had a longer operative time than TLIF patients, with a mean time of 246.5 versus 202.7 minutes (p<.01). Conversely, TLIF patients had a higher estimated blood loss during surgery (469.8 cm(3)) than AP fusion patients (311.2 cm(3)) (p<.01). The mean hospital cost for AP fusion was $25,165, whereas for TLIF was $23,390 (p=.04). The mean hospital charges and payments received for AP fusion were 1.07 (p=.05) and 1.35 (p<.01) times those received for TLIF, respectively. Therefore, mean hospital charges and payments received for TLIF were 0.93 and 0.76 times those received for AP fusion, respectively. CONCLUSIONS: Our study demonstrates that a single-level AP fusion results in longer operative time, lower blood loss during surgery, higher hospital costs, higher hospital charges, and greater payments received than a single-level TLIF. Although the decision on how best to treat a patient lies solely at the judgment of the attending surgeon, this comparative cost information may be pertinent in cases of clinical equivalence. This study also calls attention to various shortcomings that are found in present spine surgery cost-effectiveness research, as there is an ongoing need for increased standards of quality in the area of health economics research.

BACKGROUND: : Patient and surgical factors are known to influence operative blood loss in spinal fusion for adolescent idiopathic scoliosis (AIS), but have only been loosely identified. To date, there are no established recommendations to guide decisions to predonate autologous blood, and the current practice is based primarily on surgeon preference. This study is designed to determine which patient and surgical factors are correlated with, and predictive of, blood loss during spinal fusion for AIS. METHODS: : Retrospective analysis of 340 (81 males, 259 females; mean age, 15.2 y) consecutive AIS patients treated by a single surgeon from 2000 to 2008. Demographic (sex, age, height, weight, and associated comorbidities), laboratory (hematocrit, platelet, PT/PTT/INR), standard radiographic, and perioperative data including complications were analyzed with a linear stepwise regression to develop a predictive model of blood loss. RESULTS: : Estimated blood loss was 907+/-775 mL for posterior spinal fusion (PSF, n=188), 323+/-171 mL for anterior spinal fusion (ASF, n=124), and 1277+/-821 mL for combined procedures (n=28). For patients undergoing PSF, stepwise analysis identified sex, preoperative kyphosis, and operative time to be the most important predictors of increased blood loss (P<0.05). For ASF, the mean arterial pressure at incision and the operative time were predictive (P<0.05). The following formula was developed to estimate blood loss in PSF: blood loss (mL)=C+Op-time (min)x(6.4)-pre-op T2-T12 kyphosis (degrees)x(8.7), C=233 if male and -270 if female. CONCLUSION: : We find sex, operative time, and preoperative kyphosis to be the most important predictors of increased blood loss in PSF for AIS. Mean arterial pressure and operative time were predictive of estimated blood loss in ASF. For posterior fusions, we also present a model that estimates blood loss preoperatively and can be used to guide decisions regarding predonation of blood and the use of antifibrinolytic agents. LEVEL OF EVIDENCE: : Retrospective study: Level II.

STUDY DESIGN.: Retrospective study from data from a single access surgeon at 2 hospitals. OBJECTIVE.: To increase the surgeon's awareness of iliolumbar vein (ILV) variants during the anterior approach to the lumbar spine. SUMMARY OF BACKGROUND DATA.: Although there are many advantages to using the anterior approach, serious risks are involved, namely, vascular injury. The ILV is especially vulnerable when exposing the L4 and L5 vertebrae, and its ligature is recommended to avoid massive hemorrhage from its disruption. Cadaver studies on ILV variants have mainly analyzed drainage patterns. To our knowledge, however, no studies on ILV variants have been conducted on live humans during anterior spinal surgical procedures. METHODS.: A total of 159 patients who underwent anterior spinal surgery of at least the L4-L5 levels were included. Cases not involving the L4-L5 level were excluded. Frequency of anomalous ILVs and their possible association with diagnosis (spondylolisthesis, herniated nucleus pulposus, degenerative disc disease, and stenosis), sex, comorbidities, and pelvic history was evaluated. ILV was classified into 5 types: type 0 (missing ILV), type 1 (single ILV), type 2 (2 ILVs), type 3 (3 ILVs), and type 4 (>3 ILVs). RESULTS.: Most patients had a single ILV (73%, N = 116). Multiple ILVs were found in 25.8% of cases: 27 cases (17%) for type 2, 11 cases (6.9%) for type 3, and 3 cases (1.9%) for type 4. A higher frequency of multiple ILVs was found in males (32%) than in females (19.2%) (P = 0.034). Diagnosis, comorbidity, and pelvic surgical history were not associated with the number of ILVs. CONCLUSION.: The high frequency of multiple ILVs found during the anterior approach is crucial knowledge for access surgeons, as it will help them anticipate such anomalies and thus avoid the potentially catastrophic complications of an avulsion of an unexpected extra vein.Level of Evidence: 2.