Faculty Bibliography

BACKGROUND CONTEXT: Lumbar interbody fusion (LIF) techniques have been used for years to treat a number of pathologies of the lower back. These procedures may use an anterior, posterior, or combined surgical approach. Each approach is associated with a unique set of complications, but the exact prevalence of complications associated with each approach remains unclear. PURPOSE: To investigate the rates of perioperative complications of anterior lumbar interbody fusion (ALIF), posterior/transforaminal lumbar interbody fusion (P/TLIF), and LIF with a combined anterior-posterior interbody fusion (APF). STUDY DESIGN/SETTING: Retrospective review of national data from a large administrative database. PATIENT SAMPLE: Patients undergoing ALIF, P/TLIF, or APF. OUTCOME MEASURES: Perioperative complications, length of stay (LOS), total costs, and mortality. METHODS: The Nationwide Inpatient Sample database was queried for patients undergoing ALIF, P/TLIF, or APF between 2001 and 2010 as identified via International Classification of Diseases, ninth revision codes. Univariate analyses were carried out comparing the three cohorts in terms of the outcomes of interest. Multivariate analysis for primary outcomes was carried out adjusting for overall comorbidity burden, race, gender, age, and length of fusion. National estimates of annual total number of procedures were calculated based on the provided discharge weights. Geographic distribution of the three cohorts was also investigated. RESULTS: An estimated total of 923,038 LIFs were performed between 2001 and 2010 in the United States. Posterior/transforaminal lumbar interbody fusions accounted for 79% to 86% of total LIFs between 2001 and 2010, ALIFs for 10% to 15%, and APF decreased from 10% in 2002 to less than 1% in 2010. On average, P/TLIF patients were oldest (54.55 years), followed by combined approach (47.23 years) and ALIF (46.94 years) patients (p<.0001). Anterior lumbar interbody fusion, P/TLIF, and combined surgical costs were $75,872, $65,894, and $92,249, respectively (p<.0001). Patients in the P/TLIF cohort had the greatest number of comorbidities, having the highest prevalence for 10 of 17 comorbidities investigated. Anterior-posterior interbody fusion group was associated with the greatest number of complications, having the highest incidence of 12 of the 16 complications investigated. CONCLUSIONS: These data help to define the perioperative risks for several LIF approaches. Comparison of outcomes showed that a combined approach is more expensive and associated with greater LOS, whereas ALIF is associated with the highest postoperative mortality. These trends should be taken into consideration during surgical planning to improve clinical outcomes.

Study Design. Retrospective analysis.Objective. To determine patient demographics, incidence of comorbidities and procedure-related complications, and identify risk factors associated with morbidity and mortality after spinal surgery for cauda equina syndrome (CES).Summary of Background Data. To our knowledge, no study has provided nationwide estimates of patient characteristics and procedure-related complication rates after spinal surgery for CES relative to an unaffected population.Methods. Nationwide Inpatient Sample data collected between 2001 and 2010 was analyzed. Discharges with procedural codes for lumbar spinal fusion, decompression, or discectomy were included. The CES cohort included diagnoses of CES, and the unaffected cohort included lumbar spinal pathology diagnoses. Patient demographics, incidence of comorbidities and procedure-related complications, and risk factors associated with morbidity and mortality were compared.Results. Discharges for 11,207 CES and 689,799 unaffected patients were identified. Differences between cohorts were found for demographic and hospital data. Average comorbidity indices for the CES cohort were found to be increased (0.23 vs.0.13, p< 0.0001), as well as the incidence of total procedure-related complications (18.63% vs. 13.12%, p< 0.0001). In-hospital mortality rate was significantly increased for the CES cohort (0.30% vs. 0.08%, p< 0.0001). A number of comorbidities associated with additional risk for morbidity and mortality among the CES cohort were identified.Conclusion. Relative to an unaffected population undergoing similar treatment, CES patients were more likely to have increased associated comorbidities on presentation, as well as increased complication rates with a prolonged hospital course postoperatively. CES was found to carry an increased incidence of procedure-related complications as well as in-hospital mortality. A number of comorbidities associated with additional risk for morbidity and mortality among the CES cohort were identified. This study provides clinically useful data for surgeons to educate patients at risk for morbidity and mortality as well as direct future research to improve patient outcomes.

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.

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: A retrospective review of 74 consecutive, surgical patients with neuromuscular scoliosis (NMS). OBJECTIVE: This study evaluates the distribution of hospital and operating room costs incurred during surgical correction of NMS. BACKGROUND DATA: Recent studies have demonstrated that surgical treatment improves both medical outcomes and the quality of life in patients with progressive NMS. Characterization of the costs incurred at the time of surgery and hospitalization will facilitate the identification of opportunities for cost reduction. METHODS: Demographic data collected included gender, age, preoperative height, weight, and BMI. Major coronal curvatures and T5-T12 kyphosis were assessed from radiographs. Construct type and number of screws, hooks, and wires implanted were recorded. Surgical costs were calculated based on cost of surgical correction, hospital stay, and postoperative care. RESULTS: Mean age was 15.8 +/- 7.3 years; 57% were male. Comorbidities included cerebral palsy (28%) and familial dysautonomia (14%). The mean preoperative major curve magnitude was 60 degrees ; minor curve magnitude was 33 degrees . Posterior approach (76%) and pedicle screws (75%) were predominantly utilized. The average length of hospitalization was 8 days (range: 3 to 47). There were six major complications (8%). The total surgical cost was $50,096 +/- $23,998. The highest individual cost was for implants ($13,916; 24% of total costs). The second highest was inpatient room and ICU costs ($12,483; 22%); bone grafts were the third ($6,398; 11%). Increased major and minor structural curve, increased total (A/P) levels fused, and increased length of hospital stay predicted an increase in total cost. CONCLUSIONS: Major contributors to cost in NMS surgery are implants, inpatient room and ICU costs, and bone grafts. Independent predictors of higher cost are the degree of major and minor structural curve, total number of A/P levels fused, and length of hospital stay. These conclusions provide insight into costs associated with care for a medically fragile and challenging patient population.

BACKGROUND CONTEXT: Surgical planning is essential to attaining adequate radiographic correction, however, there are multiple methods of planning osteotomy procedures. Additionally, several surgical planning parameters are involved in the attempt to achieve ideal spinopelvic alignment in operative cases of adult spinal deformity. It is important for the surgeon to not only understand necessary radiographic thresholds but also to utilize available planning techniques prior to performing surgery. PURPOSE: The purpose of this study was to compare two methods of planning sagittal plane correction, a geometric and a validated formula. STUDY DESIGN/SETTING: Prospective consecutive case series. PATIENT SAMPLE: 26 adult spinal deformity patients requiring sagittal realignment. OUTCOME MEASURES: Radiographic parameters. METHODS: Prospective review of 26 adult patients with realignment procedures. Preoperative surgical plans were collected preop, defining the expected change in lumbar lordosis (LL) and in max kyphosis (mTK). Plan was based on geometrical method as well as a validated formula to predict postoperative SVA and PT. Periop long cassette and postop x-rays were obtained. Expected, predicted, and radiographic measurements (pre- peri-, and postop) were compared. RESULTS: For 6 patients, planning or perioperative X-ray images were unusable due to radiographic quality. The comparison of the two planning methods on the remaining 20 patients revealed significant differences in the planned LL, but no significant difference in mTK or predicted PT and SVA. Respectively 6 (geometric) and 12 (formula) patients were planned to reach IA in all 3 parameters. The comparison of intraoperative radiographs with the planning demonstrated an intra-operative under-correction of LL. Perioperative radiographs were a good prediction of postoperative LL, but a poor predictor of mTK. Postoperative change in mTK was underestimated with the 2 planning methods. Finally, 12 of the 14 patients planned to reach IA in SVA reac!

BACKGROUND CONTEXT: The effects of spinal fusion on gait kinematics in AIS are poorly understood. Center of mass (COM) displacement during gait has been used as an indicator of gait efficiency with the least energy consumption when the COM travels in a straight line. PURPOSE: Sixteen patients with adolescent idiopathic scoliosis (AIS) were studied for the interaction between center of mass and center of pressure (COM-COP) before and after scoliosis fusion surgery to evaluate the effect of fusion and curve correction on measures of balance and efficiency during gait. STUDY DESIGN/SETTING: Prospective clinical cohort. PATIENT SAMPLE: 16 subjects with operative AIS. OUTCOME MEASURES: COM and COP interaction and COM sway. METHODS: Prospective clinical, radiographic, and formal 3D motioncapture gait analysis were collected pre- and post spinal fusion for AIS (n, 5, 16). COM-sway was calculated based on side-to-side displacement from a straight line fitted to the patient's path. In sagittal and coronal planes, the left- and right-sided peak COM-COP inclination angles were also measured during gait. Pre- and Postoperative COM sway, and sagittal/coronal plane left- and right-sided peak inclination angles were evaluated with paired t-test. Multivariate analysis was used to identify radiographic parameters with the greatest influence on motion. RESULTS: Sixteen patients (12 females, age 14.4 +/- 3.8 at surgery, with predominantly 1AN and 5CN curves) were included in the analysis. Sixteen patients were included in the analysis. The preoperative COM peak lateral displacement decreased from a mean of 7.2 cm (SD58.0) to 2.6 cm (SD52.5) (p=0.012). In the sagittal plane left pre- and postoperative means of peak inclination angles were 25.6degree and 21.6degree (p=0.029), and right pre- and postoperative means were 26.4 and 22.8 (p=0.026), while left and right coronal peak inclination did not reach significance (p=0.349 and 0.055, respectively). A multivariate linear regression identified changes in sagittal al!

BACKGROUND CONTEXT: Pre-donation of autologous blood prior to spine fusion for adolescent idiopathic scoliosis (AIS) has been common practice. However, the effect of predonation on pre-incision hematocrit has not been studied. This study aims to determine if pre-donation of autologous blood leads to a lower pre-incision hematocrit. PURPOSE: To compare the effects of autologous blood donation on preincisional hematocrit levels. STUDY DESIGN/SETTING: Retrospective cohort study of prospective randomized trial. PATIENT SAMPLE: Patients (ages 10-21) undergoing posterior spinal fusion in a prospective, randomized controlled trial in which 125 patients were randomized to TXA, EACA, or Saline for surgery from January 2009 to January 2011. Of the 125 patients that enrolled in the study, 28 patients donated blood and 62 patients did not donate blood. 35 patients were omitted as the autologous blood donation status was not clearly documented in the medical record. OUTCOME MEASURES: Primary outcome measure was the pre-incisional hematocrit of patients immediately prior to surgery. METHODS: This is a retrospective review of data from a prospective, randomized controlled trial in which 125 patients were randomized to TXA, EACA, or Saline for surgery from January 2009 to January 2011. As part of the prospective study, all patients had a complete blood count (CBC) drawn just prior to incision. Of the 125 patients that enrolled in the study, 28 patients donated blood and 62 patients did not donate blood. 35 patients were omitted as the autologous blood donation status was not clearly documented in the medical record. Patient demographics and CBC values were compared between groups using a T-test. Statistical significance was achieved at P<0.05. RESULTS: Pre-donation patients (n528) had an average age of 15.662.2and were 75% female (21F, 7M) which was comparable to non-donation patients (n562) who had a mean age of 15.0 +/- 2.3 and were 82% female (51F, 11M) (p=0.259, p=0.425 respectively). However, pre-donation!

BACKGROUND CONTEXT: Previous analysis of acute (8 weeks) perioperative complications in a prospective, multi-center, consecutive ASD cohort demonstrated no differences in major, infectious, wound, neurological or complications requiring surgery for ASD patients receiving BMP vs patients not receiving BMP. PURPOSE: The purpose of this study was to evaluate and compare the complication rates for the same operative cohorts at one year postoperative. STUDY DESIGN/SETTING: Multi-center, 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, wound seroma/hematoma, neurological, operative, cardiovascular, renal, and gastrointestinal and complications requiring surgery. METHODS: Multicenter, prospective analysis of postoperative complications for consecutive ASD patients receiving BMP (BMP) or no BMP (NOBMP). Inclusion criteria: ASD, age >=18 years, spinal fusion >=4 levels, complete demographic, radiographic, and operative data, and minimum one-year follow up. ASD5scoliosis >=20 degrees, sagittal vertical axis (SVA) >=5 cm, pelvic tilt (PT) >=25 degrees, or thoracic kyphosis (TK) >60 degrees. Total, major, minor and specific complications evaluated. Multivariate adaptive regression splines analysis (MARS) performed. RESULTS: 261 patients, mean follow up 30.3 months (range 12.2-47.9), met inclusion criteria. BMP (n5158; average posterior (PSF) dose 2.5mg/ level, average interbody dose 5 mg/level) and NOBMP (n5 103) had similar preoperative demographic and radiographic values. Mean PSF levels were similar (BMP=12, NOBMP=12.1; p>0.05). BMP had greater operative time, osteotomies/patient, and anteroposterior surgery (p<0.05). Total and minor complications/ patient were greater for BMP vs NOBMP (1.4 vs 0.6, and 0.3 vs 0.9; p<0.05). Major, neurological, wound complications and infections/patient were similar!

BACKGROUND CONTEXT: Incremental cost-utility analysis is critical to the efficient allocation of health care resources, but few cost-utility studies currently exist in the adult spinal deformity (ASD) literature. PURPOSE: Examine the cost-effectiveness of surgical treatment of ASD with extended follow-up on observed costs, payments, and quality-adjusted life-years (QALYs) following index surgery, including any related readmissions. STUDY DESIGN/SETTING: Single-center, retrospective, consecutive case series. PATIENT SAMPLE: 239 consecutive patients undergoing primary surgery for ASD with three-year follow-up data, out of 278 patients eligible for three-year follow-up. OUTCOME MEASURES: Payments (expressed in 2010 dollars) to the hospital were collected from administrative data, with QALYs calculated from the SF-6D. Minimum three-year follow-up was required. METHODS: Payments and QALYs were discounted at 3.5% per year. The study analyzed the average cost-effectiveness ratio (ACER) and a range of incremental cost-effectiveness ratios (ICERs) based on improvement in QALYs from baseline and alternative assumptions of the reduction in health-related quality-of-life (HRQOL) without surgical intervention. Results were projected through 10-year follow-up, and 95% confidence intervals (CIs) were calculated using nonparametric bootstrap methods. RESULTS: Patients were predominantly female (n5203, 85%) with average age of 49 (range 18 to 82). Total discounted per-patient payments averaged >=211,529, including any readmissions over the follow-up period. Discounted QALYs averaged 1.9 over 3-year follow-up. Projecting through 10-year follow-up, the ACER (>=/QALY) was >=37,973 (95% CI; >=35,123 to >=41,066). ICERs ranged from >=58,027 (95% CI; >=53,537 to >=63,271) based on an assumed 20% reduction in quality-of-life per year without surgery to >=357,950 (95% CI; >=276,276 to >=475,997) assuming no reduction in quality-of-life without surgery. CONCLUSIONS: This study considers the cost-effectiveness of surgica!