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David W. Polly Jr.

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Timothy R. Kuklo, Michael K. Rosner and David W. Polly Jr.

Object

Synthetic bioabsorbable implants have recently been introduced in spinal surgery; consequently, the indications, applications, and results are still evolving. The authors used absorbable interbody spacers (Medtronic Sofamor Danek, Memphis, TN) packed with recombinant bone morphogenetic protein (Infuse; Medtronic Sofamor Danek) for single- and multiple-level transforaminal lumbar interbody fusion (TLIF) procedures over a period of 18 months. This is a consecutive case series in which postoperative computerized tomography (CT) scanning was used to assess fusion status.

Methods

There were 22 patients (17 men, five women; 39 fusion levels) whose mean age was 41.6 years (range 23–70 years) and in whom the mean follow-up duration was 12.4 months (range 6–18 months). Bridging bone was noted as early as the 3-month postoperative CT scan when obtained; solid arthrodesis was routinely noted between 6 and 12 months in 38 (97.4%) of 39 fusion levels. In patients who underwent repeated CT scanning, the fusion mass appeared to increase with time, whereas the disc space height remained stable. Although the results are early (mean 12-month follow-up duration), there was only one noted asymptomatic delayed union/nonunion at L5–S1 in a two-level TLIF with associated screw breakage. There were no infections or complications related to the cages.

Conclusions

The bioabsorbable cages appear to be a viable alternative to metal interbody spacers, and may be ideally suited to spinal interbody applications because of their progressive load-bearing properties.

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David W. Polly Jr., Michael K. Rosner, William Monacci and Ross R. Moquin

Hemivertebrae are a common cause of congenital scoliosis. Depending on their location and the magnitude of the resultant deformity, they may be asymptomatic or require treatment. In the past, treatment has focused on prevention of deformity progression in growing children. Little has been written about congenital scoliosis presenting in adulthood. Because the aging of the spine is a kyphosing process and hemivertebrae often present with a local segmental kyphotic alignment, this can become symptomatic. Excision of hemivertebrae is well established as a safe and effective procedure when treatment is required. Initially this was conducted via a combined anterior–posterior approach. Recently some authors have indicated that in the lumbar spine hemivertebra resection can safely and effectively be achieved via a single posterior transpedicular approach. The authors report two adult cases in which they performed posterior transpedicular lateral extracavitary excision of a thoracic, fully segmented hemivertebrae. Essentially complete correction of the deformity was achieved. There were no neurological complications. The patients were spared a thoracotomy and no chest tubes were required.

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Doniel Drazin, Terrence T. Kim, David W. Polly Jr and J. Patrick Johnson

Image-guided surgery (IGS) has been evolving since the early 1990s and is now used on a daily basis in the operating theater for spine surgery at many institutions. In the last 5 years, spinal IGS has greatly benefitted from important enhancements including portable intraoperative CT (iCT) coupled with high-speed computerized stereotactic navigation systems and optical-based camera tracking technology.

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Christopher I. Shaffrey and Justin S. Smith

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Osa Emohare, Alison Dittmer, Robert A. Morgan, Julie A. Switzer and David W. Polly Jr.

OBJECT

Recently published data make it possible to generate estimates of bone mineral density (BMD) by using CT attenuation; this innovation can save time and reduce costs. Although advanced age is associated with reduced BMD, especially in patients with a fracture of C-2, relatively few patients ever undergo formal dual x-ray absorptiometry studies. To the authors' knowledge, this is the first study to assess the utility of this technique in elucidating BMD in patients with an acute fracture of the cervical spine.

METHODS

Patients who presented to a Level I trauma center with an acute fracture of the cervical spine and underwent abdominal (or L-1) CT scanning either at admission or in the 6 months before or after the injury were evaluated. Using a picture-archiving and communication system, the authors generated regions of interest of similar size in the body of L-1 (excluding the cortex) and computed mean values for CT attenuation. The values derived were compared with threshold values, which differentiate between osteoporotic and nonosteoporotic states; age-stratified groups were also compared.

RESULTS

Of the 91 patients whose data were reviewed, 51 were < 65 years old (mean 43.2 years) and 40 were ≥ 65 years old (mean 80.9 years). The overall mean CT attenuation values (in Hounsfield units [HU]), stratified according to age, were 193.85 HU for the younger cohort and 117.39 HU for the older cohort; the result of a comparison between these two values was significant (p < 0.001).

CONCLUSIONS

Using opportunistic CT scanning, this study demonstrates the relative frequency of osteoporosis in acute fractures of the cervical spine. It also objectively correlates overall BMD with the known higher frequency of C-2 fractures in older patients. This technique harnesses the presence of opportunistic CT scans of the abdomen, which potentially reduces the need for the extra time and cost that may be associated with dual x-ray absorptiometry scanning.

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Sharon C. Yson, Edward Rainier G. Santos, Jonathan N. Sembrano and David W. Polly Jr.

Object

In this paper the authors sought to determine the segmental lumbar sagittal contour change after bilateral transforaminal lumbar interbody fusion (TLIF).

Methods

Between March 2007 and October 2010, 42 consecutive patients (57 levels) underwent bilateral TLIF. Standard preoperative and 6-week postoperative standing lumbar spine radiographs were examined. Preoperative and postoperative segmental lordosis was determined by manual measurements using the Cobb method. The difference between the preoperative and postoperative values were calculated and analyzed for statistical significance.

Results

The mean preoperative segmental alignment was 8.1°. The mean postoperative alignment was 15.3°, with a mean correction of 7.2° per segment. The largest gain in lordosis was obtained at the L5–S1 level (10.1°). There was a significant difference between the preoperative and postoperative values (p = 5 × 10−9). There was no significant difference in mean segmental correction between levels. Improvement in lordosis was higher in multilevel fusions (9.8°) than in single-level fusions (5.2°) (p = 0.047). There was an inverse correlation between preoperative sagittal lordosis measurement and change in lordosis (r = −0.599).

Conclusions

A significant improvement in lumbar lordosis can be gained by preforming bilateral facetectomies in TLIF with posterior compression. This procedure provides an additional option to a spine surgeon's armamentarium in dealing with significant lumbar sagittal plane deformities.

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Michael K. Rosner, David W. Polly Jr., Timothy R. Kuklo and Stephen L. Ondra

Techniques to improve segmental fixation have advanced the ability to correct complex spinal deformity. The purpose of instrumentation is to correct spinal deformity or to stabilize the spine to enhance the long-term biological fusion. The ultimate goal of spinal deformity surgery is the creation of a stable, balanced, pain-free spine centered over the pelvis in the coronal and sagittal planes. The minimum number of segments should be fused. These concepts remain challenging in the setting of deformity and instability. Successful results can be obtained if the surgeon understands the technology available, its capabilities, biological limitations, and the desired solution.

The authors prefer to use thoracic pedicle screws when treating patients with spinal deformity because they provide greater corrective forces for realignment. This allows shorter-segment constructs and the possibility of true derotation in correction. In this article the authors focus on the use of thoracic transpedicular screw fixation in the management of complex spinal disorders and deformity.

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Stacey J. Ackerman, David W. Polly Jr., Tyler Knight, Tim Holt and John Cummings Jr.

Object

Low-back pain (LBP) is highly prevalent among older adults, and the cost to treat the US Medicare population is substantial. Recent US health care reform legislation focuses on improving quality of care and reducing costs. The sacroiliac (SI) joint is a recognized generator of LBP, but treatments traditionally have included either nonoperative medical management or open SI joint fusion, which has a high rate of complications. New minimally invasive technologies have been developed to treat SI joint disruption and degenerative sacroiliitis, so it is important to understand the current cost impact of nonoperative care to the Medicare program. The objective of this study was to evaluate the medical resource use and associated Medicare reimbursement for patients managed with nonoperative care for degenerative sacroiliitis/SI joint disruption.

Methods

A retrospective study was conducted using claim-level data from the Medicare 5% Standard Analytical Files (SAFs) for the years 2005–2010. Included were patients with a primary ICD-9-CM (International Classification of Diseases, Ninth Revision, Clinical Modification) diagnosis code for degenerative sacroiliitis/SI joint disruption (ICD-9-CM diagnosis codes 720.2, 724.6, 739.4, 846.9, or 847.3) with continuous enrollment for at least 1 year before and 5 years after diagnosis. Claims attributable to degenerative sacroiliitis/SI joint disruption were identified using ICD-9-CM diagnosis codes (claims with a primary or secondary ICD-9-CM diagnosis code of 71x.xx, 72x.xx, 73x.xx, or 84x.xx), and the 5-year medical resource use and Medicare reimbursement (in 2012 US dollars) were tabulated across practice settings. A subgroup analysis was performed among patients who underwent lumbar spinal fusion.

Results

Among all Medicare patients with degenerative sacroiliitis or SI joint disruption (n = 14,552), the mean cumulative 5-year direct medical costs attributable to degenerative sacroiliitis/SI joint disruption was $18,527 ± $28,285 (± SD) per patient. The cumulative 5-year cost was $63,913 ± $46,870 per patient among the subgroup of patients who underwent lumbar spinal fusion (n = 538 [3.7%]) and $16,769 ± $25,753 per patient among the subgroup of patients who had not undergone lumbar spinal fusion (n = 14,014 [96.3%]). For the total population, the largest proportion of cumulative 5-year costs was due to inpatient hospitalization (42.1%), outpatient physician office (20.6%), and hospital outpatient costs (14.9%). The estimated cumulative 5-year Medicare reimbursement across practice settings attributable to SI joint disruption or degenerative sacroiliitis is approximately $270 million among these 14,552 Medicare beneficiaries ($18,527 per patient).

Conclusions

In patients who suffer from LBP due to SI joint disruption or degenerative sacroiliitis, this retrospective Medicare claims data analysis demonstrates that nonoperative care is associated with substantial costs and medical resource utilization. The economic burden of SI joint disruption and degenerative sacroiliitis among Medicare beneficiaries in the US is substantial and highlights the need for more cost-effective therapies to treat this condition and reduce health care expenditures.

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Ian McCarthy, Michael O'Brien, Christopher Ames, Chessie Robinson, Thomas Errico, David W. Polly Jr. and Richard Hostin

Object

Incremental cost-effectiveness analysis is critical to the efficient allocation of health care resources; however, the incremental cost-effectiveness ratio (ICER) of surgical versus nonsurgical treatment for adult spinal deformity (ASD) has eluded the literature, due in part to inherent empirical difficulties when comparing surgical and nonsurgical patients. Using observed preoperative health-related quality of life (HRQOL) for patients who later underwent surgery, this study builds a statistical model to predict hypothetical quality-adjusted life years (QALYs) without surgical treatment. The analysis compares predicted QALYs to observed postoperative QALYs and forms the resulting ICER.

Methods

This was a single-center (Baylor Scoliosis Center) retrospective analysis of consecutive patients undergoing primary surgery for ASD. Total costs (expressed in 2010 dollars) incurred by the hospital for each episode of surgical care were collected from administrative data and QALYs were calculated from the 6-dimensional Short-Form Health Survey, each discounted at 3.5% per year. Regression analysis was used to predict hypothetical QALYs without surgery based on preoperative longitudinal data for 124 crossover surgical patients with similar diagnoses, baseline HRQOL, age, and sex compared with the surgical cohort. Results were projected through 10-year follow-up, and the cost-effectiveness acceptability curve (CEAC) was estimated using nonparametric bootstrap methods.

Results

Three-year follow-up was available for 120 (66%) of 181 eligible patients, who were predominantly female (89%) with average age of 50. With discounting, total costs averaged $125,407, including readmissions, with average QALYs of 1.93 at 3-year follow-up. Average QALYs without surgery were predicted to be 1.6 after 3 years. At 3- and 5-year follow-up, the ICER was $375,000 and $198,000, respectively. Projecting through 10-year follow-up, the ICER was $80,000. The 10-year CEAC revealed a 40% probability that the ICER was $80,000 or less, a 90% probability that the ICER was $90,000 or less, and a 100% probability that the ICER was less than $100,000.

Conclusions

Based on the WHO's suggested upper threshold for cost-effectiveness (3 times per capita GDP, or $140,000 in 2010 dollars), the analysis reveals that surgical treatment for ASD is cost-effective after a 10-year period based on predicted deterioration in HRQOL without surgery. The ICER well exceeds the WHO threshold at earlier follow-up intervals, highlighting the importance of the durability of surgical treatment in assessing the value of surgical intervention. Due to the study's methodology, the results are dependent on the predicted deterioration in HRQOL without surgery. As such, the results may not extend to patients whose HRQOL would remain steady without surgery. Future research should therefore pursue a direct comparison of QALYs for surgical and nonsurgical patients to better understand the cost-effectiveness of surgery for the average ASD patient.