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,!

Correct identification of fusion levels in surgical planning for the management of adolescent idiopathic scoliosis is a complex task. Several classification systems and algorithms exist to assist surgeons in determining the appropriate levels to be instrumented. The Lenke classification is the benchmark system. Among the many factors and measurements that are taken into account when selecting the proper upper instrumented vertebra and lower instrumented vertebra are planning for selective fusion; preserving motion segments; preventing proximal and/or distal junctional kyphosis, shoulder imbalance, and neck pain; and maintaining short fusion lengths. Existing treatment algorithms do not account for every exception, and further research is required to improve long-term surgical outcomes.

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.

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 ).

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.

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: The increased prevalence of spinal fusion surgery has created an industry focus on bone graft alternatives. While autologous bone graft remains the gold standard, the complications and morbidity from harvesting autologous bone drives the search for reliable and safe bone graft substitutes. With the recent information about the adverse events related to bone morhogenetic protein use, it is appropriate to review the literature about the numerous products that are not solely bone morphogenetic protein. PURPOSE: The purpose of this literature review is to determine the recommendations for use of non-bone morphogenetic protein bone graft alternatives in the most common spine procedures based on a quantifiable grading system. STUDY DESIGN: Systematic literature review. METHODS: A literature search of MEDLINE (1946-2012), CINAHL (1937-2012), and the Cochrane Central Register of Controlled Trials (1940-April 2012) was performed, and this was supplemented by a hand search. The studies were then evaluated based on the Guyatt criteria for quality of the research to determine the strength of the recommendation. RESULTS: In this review, more than one hundred various studies on the ability of bone graft substitutes to create solid fusions and good patient outcomes are detailed. CONCLUSION: The recommendations for use of bone graft substitutes and bone graft extenders are based on the strength of the studies and given a grade.

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.

STUDY DESIGN.: A retrospective review. OBJECTIVE.: To compare the radiographical and clinical profiles between 2 surgical approaches for the correction of sagittal plane spinal deformity. SUMMARY OF BACKGROUND DATA.: Sagittal plane decompensation is the radiographical parameter that carries the greatest impact on adverse outcomes. Surgical correction methods are heterogeneous, and opposing views pervade the spine community in consideration of the most effective approach and techniques to achieve correction. METHODS.: A total of 33 cases with sagittal spinal deformity were assessed according to their surgical approach, posterior only versus combined anteroposterior group. Comparison was based on the demographic data, and radiographical parameters included pelvic tilt, pelvic incidence, sacral slope, lumbar lordosis, thoracic kyphosis, and sagittal vertical axis. RESULTS.: Twenty two subjects were identified for the posterior-only and 11 subjects for the anteroposterior group. Average age was 58.7 years in the posterior-only and 55.7 years for the combined approach. Preoperative mean sagittal vertical axis was 186.6 and 147.7 mm, for the posterior-only and combined approaches, respectively (P = 0.1). Preoperative mean pelvic tilt was 34.2 degrees for the posterior-only and 36.9 degrees for the combined approach group (P = 0.5). A greater operative time for the combined approach was significant, 535 versus 333 minutes for the posterior-only approach (P < 0.001). In the posterior-only group, 8 of 22 patients and 7 of 11 patients in the combined-approach cohort experienced a postoperative complication (P = 0.16). The average follow-up was 41.8 and 47.7 months for the posterior-only and combined approaches, respectively (P = 0.4). CONCLUSION.: A posterior-only or combined surgical approach had comparable radiographical outcomes. Higher morbidity was significant in regard to operative time in the combined-approach group. Deciding on the approach best suited for achieving correction in the sagittal plane likely resides on the surgeon's experience and expertise.