Prognostic Factors Impacting Surgical Outcomes in Patients With Cervical Spondylotic Myelopathy.

The purpose of surgical decompression in patients who have CSM is to stop the progression of symptoms and hopefully improve function. It is critical to understand prognostic factors that affect the outcome. Factors intrinsic to the patient that can adversely affect outcomes include diabetes, older age, tobacco use, the presence of mental health disease, and obesity. MRI imaging findings of T2 hyperintensity and clinical duration and severity of symptoms is also associated with poorer outcomes. Patients should be counseled regarding the efficacy of decompressive procedures for CSM and given realistic expectations based on their unique biophysical profiles.

The Feasibility of Translaminar Screws in the Subaxial Cervical Spine: Computed Tomography and Cadaveric Validation.

BACKGROUND: The use of translaminar screws may serve as a viable salvage method for complicated cases. To our understanding, the study of the feasibility of translaminar screw insertion in the actual entire subaxial cervical spine has not been carried out yet. The purpose of this study was to report the feasibility of translaminar screw insertion in the entire subaxial cervical spine. METHODS: Eighteen cadaveric spines were harvested from C3 to C7 and 1-mm computed tomography (CT) scans and three-dimensional reconstructions were created to exclude any bony anomaly. Thirty anatomically intact segments were collected (C3, 2; C4, 3; C5, 3; C6, 8; and C7, 14), and randomly arranged. Twenty-one segments were physically separated at each vertebral level (group S), while 9 segments were not separated from the vertebral column and left in situ (group N-S). CT measurement of lamina thickness was done for both group S and group N-S, and manual measurement of various length and angle was done for group S only. Using the trajectory proposed by the previous studies, translaminar screws were placed at each level. Screw diameter was the same or 0.5 mm larger than the proposed diameter based on CT measurement. Post-insertion CT was performed. Cortical breakage was checked either visually or by CT. RESULTS: When 1° and 2° screws of the same size were used, medial cortex breakage was found 13% and 33% of the time, respectively. C7 was relatively safer than the other levels. With larger-sized screws, medial cortex breakage was found in 47% and 46% of 1° and 2° screws, respectively. There were no facet injuries due to the screws in group N-S. CONCLUSIONS: Translaminar screw insertion in the subaxial cervical spine is feasible only when the lamina is thick enough to avoid any breakage that could lead to further complications. The authors do not recommend inserting translaminar screws in the subaxial cervical spine except in some salvage cases in the presence of a thick lamina.

Evaluation of Gait and Functional Stability in Preoperative Cervical Spondylotic Myelopathy Patients.

STUDY DESIGN: Prospective cohort study. OBJECTIVE: The aim of this study was to 1) determine postural stability and spatiotemporal gait parameters and 2) characterize dynamic stability and variances in angular momentum (AM) of preoperative cervical spondylotic myelopathy (CSM) patients compared with healthy controls. SUMMARY OF BACKGROUND DATA: CSM is the most common cause of spinal cord dysfunction in the world and can lead to significant functional deficits including proprioception and gait disturbances. Biomechanical feedback mechanisms compensating for these deficits, specifically AM regulation, have remained largely unexplored. METHODS: Fifty-six subjects: 32 preoperative Nurick grade 2 or 3 CSM patients and 24 controls were included. Standing balance trials were performed on a single force plate, while walking trials were conducted at self-selected pace over a 15 m runway and a series of five force plates. All trials were recorded with three-dimensional motion analysis cameras and gait modeling software was utilized to calculate stability, spatiotemporal gait parameters, and joint kinematics. RESULTS: Tilted ellipse area, a measure of center of pressure variance and postural stability, was significantly greater among CSM patients (847.54 ±â€Š764.33 mm2vs. 258.18 ±â€Š103.35 mm2, P < 0.001). These patients had two times as much variance medial-lateral (72.12 ±â€Š51.83 mm vs. 29.15 ±â€Š14.95 mm, P = 0.001) and over three times as much anterior-posterior (42.25 ±â€Š55.01 mm vs. 9.17 ±â€Š4.83 mm, P = 0.001) compared with controls. Spatiotemporal parameters indicated that the CSM patients tending to have slower, shorter, and wider gait compared with controls, while spending greater amount of time in double support. Compensatory AM among CSM patients was significantly increased in all three anatomic planes, where whole-body AM was approximately double that of controls (0.057 ±â€Š0.034 vs. 0.023 ±â€Š0.006), P < 0.001). CONCLUSION: Preoperative CSM patients showed significant alterations in spatiotemporal gait parameters and postural stability compared with controls, consistent with prior literature. Likewise, angular momentum analysis demonstrates that these patients have globally increased body excursion to maintain dynamic balance.Level of Evidence: 3.

Lumbosacral Spondylolysis and Spondylolisthesis.

Repetitive stress on the lumbosacral spine during sporting activity places the athletic patient at risk of developing symptomatic pars defect. Clinical history, physical examination, and diagnostic imaging are important to distinguish spondylolysis from other causes of lower back pain. Early pars stress reaction can be identified with advanced imaging, before the development of cortical fracture or vertebral slip progression to spondylolisthesis. Conservative management is first-line for low-grade injury with surgical intervention indicated for refractory symptoms, severe spondylolisthesis, or considerable neurologic deficit. Prompt diagnosis and management of spondylolysis leads to good outcomes and return to competition for most athletes.

Fluoroscopically Guided Facet Cyst Rupture: Rate of Conversion to Surgery and Risk Factor Analysis.

STUDY DESIGN: Retrospective case series at a single academic medical center. OBJECTIVE: The aim was to determine if specific clinical, radiologic, and procedural factors are associated with conversion to surgery after fluoroscopically guided cyst rupture. SUMMARY OF BACKGROUND DATA: Percutaneous fluoroscopic rupture of facet cysts can often be the definitive treatment; however, it is unknown before the procedure who will ultimately proceed to formal surgical decompression. Differences in clinical, radiographic, and procedural factors of facet cysts may relate to the difference in efficacy of fluoroscopically guided cyst rupture. METHODS: A continuous cohort of 45 patients who underwent fluoroscopically guided cyst rupture was evaluated. The primary outcome measured rate of conversion to surgery and of those that underwent surgery, the rate of decompression and fusion compared with fusion alone was noted. Secondary outcomes included analysis of clinical, radiologic, and procedural variables to determine if there were risk factors associated with conversion to surgery. RESULTS: Twenty-nine percent of patients eventually underwent a surgical procedure with an average interval to surgery of 95 days after attempted rupture. Thirty-eight percent of patients that underwent surgery had a decompression and fusion. Failure of percutaneous cyst rupture trended toward significance for a future surgical decompression (P=0.08). CONCLUSIONS: Percutaneous facet cyst rupture is potentially a definitive treatment for this condition; however, it is unknown ahead of time who will proceed to definitive surgical decompression. On the basis of the data in this study, less than one-third of patients who had a fluoroscopically guided facet cyst rupture went on to surgery. There were no clinical, radiographic, or procedural details which could be used to robustly predict failure of percutaneous treatment. At this time, it is recommended to continue to attempt this nonoperative treatment intervention when there is a clinical indication after discussion of the risks and benefits with the patient.

Risk of Surgical Site Infection and Mortality Following Lumbar Fusion Surgery in Patients With Chronic Steroid Usage and Chronic Methicillin-Resistant Staphylococcus aureus Infection.

STUDY DESIGN: A retrospective database analysis among Medicare beneficiaries OBJECTIVE.: The aim of this study was to determine the effect of chronic steroid use and chronic methicillin-resistant Staphylococcus aureus (MRSA) infection on rates of surgical site infection (SSI) and mortality in patients 65 years of age and older who were treated with lumbar spine fusion. SUMMARY OF BACKGROUND DATA: Systemic immunosuppression and infection focus elsewhere in the body are considered risk factors for SSI. Chronic steroid use and previous MRSA infection have been associated with an increased risk of SSI in some surgical procedures, but their impact on the risk of infection and mortality after lumbar fusion surgery has not been studied in detail. METHODS: The PearlDiver insurance-based database (2005-2012) was queried to identify 360,005 patients over 65 years of age who had undergone lumbar spine fusion. Of these patients, those who had been taking oral glucocorticoids chronically and those with a history of chronic MRSA infection were identified. The rates of SSI and mortality in these two cohorts were compared with an age- and risk-factor matched control cohort and odds ratio (OR) was calculated. RESULTS: Chronic oral steroid use was associated with a significantly increased risk of 1-year mortality [OR = 2.06, 95% confidence interval (95% CI) 1.13-3.78, P = 0.018] and significantly increased risk of SSI at 90 days (OR = 1.74, 95% CI 1.33-1.92, P < 0.001) and 1 year (OR = 1.88, 95% CI 1.41-2.01, P < 0.001). Chronic MRSA infection was associated with a significantly increased risk of SSI at 90 days (OR = 6.99, 95% CI 5.61-9.91, P < 0.001) and 1 year (OR = 24.0, 95%CI 22.20-28.46, P < 0.001) but did not significantly impact mortality. CONCLUSION: Patients over 65 years of age who are on chronic oral steroids or have a history of chronic MRSA infection are at a significantly increased risk of SSI following lumbar spine fusion. LEVEL OF EVIDENCE: 3.

Unplanned Immediate Return to Operating Room After Spine Surgery: Significance of Immediate Postoperative Radiographs.

STUDY DESIGN: Retrospective analysis; single center data. OBJECTIVE: The purpose of this study is to look at the utility and relevance of immediate postoperative radiographs in providing vital information leading to immediate revision after spine surgery. SUMMARY OF BACKGROUND DATA: Immediate postoperative radiographs are routinely obtained in the recovery room after spine surgery to verify the level, alignment of the spine, implant position, and the adequacy of the procedure. However, with the ability to utilize intraoperative fluoroscopy imaging for the same purpose, the requirement for immediate postoperative radiographs needs to be validated. The purpose of this study is to look at the utility and relevance of these postoperative radiographs in providing critical information that may warrant immediate intervention. METHODS: Retrospective analysis of all spine surgeries (elective and emergent), performed at a single center from 2011 to 2016, was done and cases returning to operating room within 48 hours were identified. Indication of immediate revision was reviewed and utility of immediate postoperative radiographs in guiding immediate revision was analyzed. RESULTS: A total of 1804 elective and urgent spinal surgeries were performed by seven surgeons. Twenty-two patients returned to operating room within 48 hours of their index procedures. Of these 22 cases, only two patients were noted to have positive findings on recovery room radiographs. The findings of suboptimal spinal alignment or failed instrumentation led to the immediate revision in both cases. Both cases involved instrumentation at cervicothoracic region and intraoperative imaging provided only limited visualization. CONCLUSION: Routine recovery room radiographs played a role in the decision to emergently return to the operating room in 0.10% (2/1804) cases at our institution. The potential benefit of immediate recovery room radiographs after spine surgery should be weighed against the added healthcare cost and patient discomfort associated with obtaining these radiographs routinely. Imaging may be delayed to a more elective time without any significant risk in majority of spine cases. LEVEL OF EVIDENCE: 3.

Quantitative Assessment of the Anatomical Footprint of the C1 Pedicle Relative to the Lateral Mass: A Guide for C1 Lateral Mass Fixation.

STUDY DESIGN: Anatomic study. OBJECTIVES: To determine the relationship of the anatomical footprint of the C1 pedicle relative to the lateral mass (LM). METHODS: Anatomic measurements were made on fresh frozen human cadaveric C1 specimens: pedicle width/height, LM width/height (minimum/maximum), LM depth, distance between LM's medial aspect and pedicle's medial border, distance between LM's lateral aspect to pedicle's lateral border, distance between pedicle's inferior aspect and LM's inferior border, distance between arch's midline and pedicle's medial border. The percentage of LM medial to the pedicle and the distance from the center of the LM to the pedicle's medial wall were calculated. RESULTS: A total of 42 LM were analyzed. The C1 pedicle's lateral aspect was nearly confluent with the LM's lateral border. Average pedicle width was 9.0 ± 1.1 mm, and average pedicle height was 5.0 ± 1.1 mm. Average LM width and depth were 17.0 ± 1.6 and 17.2 ± 1.6 mm, respectively. There was 6.9 ± 1.5 mm of bone medial to the medial C1 pedicle, which constituted 41% ± 9% of the LM's width. The distance from C1 arch's midline to the medial pedicle was 13.5 ± 2.0 mm. The LM's center was 1.6 ± 1 mm lateral to the medial pedicle wall. There was on average 3.5 ± 0.6 mm of the LM inferior to the pedicle inferior border. CONCLUSIONS: The center of the lateral mass is 1.6 ± 1 mm lateral to the medial wall of the C1 pedicle and approximately 15 mm from the midline. There is 6.9 ± 1.5 mm of bone medial to the medial C1 pedicle. Thus, the medial aspect of C1 pedicle may be used as an anatomic reference for locating the center of the C1 LM for screw fixation.

Rheumatoid Arthritis Is Associated With an Increased Risk of Postoperative Infection and Revision Surgery in Elderly Patients Undergoing Anterior Cervical Fusion.

STUDY DESIGN: Retrospective review. OBJECTIVE: To identify the incidence and analyze the risk of postoperative complications amongst elderly patients with rheumatoid arthritis undergoing anterior cervical fusion. SUMMARY OF BACKGROUND DATA: Previous studies have reported elevated risks of postoperative complications for patients with rheumatoid arthritis undergoing orthopedic procedures. However, little is known about the risk of postoperative complications in rheumatoid arthritis patients after spine surgery. METHODS: A commercially available database was queried for all Medicare patients 65 years of age and older undergoing one- or two-level primary anterior cervical fusion surgeries from 2005 to 2013. Complications, hospitalization costs, and length of stay were queried. Multivariate logistic regression analyses were performed to estimate the odds ratio for each complication adjusted for age, sex, and Charlson Comorbidity Index. RESULTS: A total of 6067 patients with a history of rheumatoid arthritis and 113,187 controls were identified. Significantly higher incidences of major medical complications (7.5% vs. 5.9%, P < 0.001), postoperative infections (2.6% vs. 1.5%, P < 0.001), and revision surgery (1.1% vs. 0.6%, P < 0.001) were observed amongst the rheumatoid arthritis cohort. Significantly greater average cost of hospitalization ($17,622 vs. $12,489, P < 0.001) and average length of stay (3.13 vs. 2.08 days, P < 0.001) were also observed. CONCLUSION: Patients with rheumatoid arthritis undergoing anterior cervical fusion face increased risks of postoperative infection and revision surgery compared to normal controls. This information is valuable for preoperative counseling and risk stratification. LEVEL OF EVIDENCE: 3.

Perioperative Complications Associated With Posterolateral Spine Fusions: A Study of Elderly Medicare Beneficiaries.

STUDY DESIGN: A retrospective database review. OBJECTIVE: The aim of this study was to compare the occurrence of complications in patients treated with one to two-level, three to seven-level, and more than eight level fusions. SUMMARY OF BACKGROUND DATA: Elderly patients constitute a rapidly growing demographic with an increasing need for spinal procedures. Complication rates for spinal surgery in elderly patients range from 37% to 80% with major complications occurring in 12% to 21% of patients. METHODS: The PearlDiver database (2005-2012) was utilized to compare perioperative complication rates in patients aged 65 years and older undergoing posterolateral fusion of one to two (n = 90,527); three to seven (n = 23,827), and more than eight (n = 2758) thoracolumbar levels. Cohorts were matched by demographics and comorbidities. Ninety-day medical and surgical complication and mortality rates were determined. RESULTS: In the full, unmatched cohort, the major complication rate was 15.9%, with matched cohorts of one to two, three to seven, and eight-level fusions associated with major complication rates of 12.5%, 20.5%, and 35.4%, respectively. Patients treated with 8+ level fusions had 3.8 and 2.1 times greater odds of developing a major complication than patients treated with 1 to 2 and 3 to 7-level fusions, respectively (P < 0.0001). Patients treated with more than eight-level fusions had 3.9 and 10.8 times increased odds of experiencing mortality than those treated with three to seven-level and one to two-level fusions, respectively. CONCLUSION: Elderly patients treated with spine fusions spanning more than eight levels experience significantly increased complication rates when compared with patients treated with fusions of shorter length. LEVEL OF EVIDENCE: 3.

Surgeon Reimbursement Relative to Hospital Payments for Spinal Fusion: Trends From 10-year Medicare Analysis.

STUDY DESIGN: Retrospective, economic analysis. OBJECTIVE: The aim of this study was to analyze the trend in hospital charge and payment adjusted to corresponding surgeon charge and payment for cervical and lumbar fusions in a Medicare sample population from 2005 to 2014. SUMMARY OF BACKGROUND DATA: Previous studies have reported trends and variation in hospital charges and payments for spinal fusion, but none have incorporated surgeon data in analysis. Knowledge of the fiscal relationship between hospitals and surgeons over time will be important for stakeholders as we move toward bundled payments. METHODS: A 5% Medicare sample was used to capture hospital and surgeon charges and payments related to cervical and lumbar fusion for degenerative disease between 2005 and 2014. We defined hospital charge multiplier (CM) as the ratio of hospital/surgeon charge. Similarly, the hospital/surgeon payment ratio was defined as hospital payment multiplier (PM). The year-wise and regional trend in patient profile, length of stay, discharge disposition, CM, and PM were studied for all fusion approaches separately. RESULTS: A total of 40,965 patients, stratified as 15,854 cervical and 25,111 lumbar fusions, were included. The hospital had successively higher charges and payments relative to the surgeon from 2005 to 2014 for all fusions with an inverse relation to hospital length of stay. Increasing complexity of fusion such as for anterior-posterior cervical fusion had higher hospital reimbursements per dollar earned by the surgeon. There was regional variation in how much the hospital charged and received per surgeon dollar. CONCLUSION: Hospital charge and payment relative to surgeon had an increasing trend despite a decreasing length of stay for all fusions. Although the hospital can receive higher payments for higher-risk patients, this risk is not reflected proportionally in surgeon payments. The shift toward value-based care with shared responsibility for outcomes and cost will likely rely on better aligning incentives between hospital and providers. LEVEL OF EVIDENCE: 3.

Use of the "dual construct" for the management of complex spinal reconstructions.

BACKGROUND CONTEXT: Surgical management of complex spinal reconstructions remains a clinical challenge, as pseudoarthrosis with subsequent rod breakage can occur. Increased rod density in the form of "satellite" or "outrigger" rods have been described; however, rod-fracture above or below satellite rods persist and can result in dissociation of the construct, loss of correction, and recurrence of deformity. The use of four distinct and mechanically independent rods (dual construct) reduces this concern. Since the original case description in 2006, there have been no other studies that use the dual construct for the surgical management of complex spinal reconstructions. PURPOSE: The purpose of this study is to review the long-term experience and surgical technique using the dual construct, and to present our complications, rod fracture rates, and outcomes for the surgical management of complex spinal reconstructions. STUDY DESIGN: This study used a surgical technique with case series outcomes. PATIENT SAMPLE: Patients were from a single-institute who underwent dual construct between 2010 and 2014 and who were available for 2-year follow-up. OUTCOME MEASURES: Radiographic and functional outcomes, complications, rod fracture rates, and revision surgery rates were the outcome measures. METHODS: A retrospective review was conducted from a single institution between 2010 and 2014, with a subsequent 2-year follow-up period. Extensive review of patients' medical record, radiographs, and advanced imaging where available was performed. Medical record was evaluated for patient demographics, surgical procedure, and complications. Radiographic measurements included presence or absence of implant failure and proximal junctional kyphosis or distal junctional kyphosis. RESULTS: A total of 36 patients underwent surgical reconstruction. The average estimated blood loss was 1,856 cc (range, 400-4,000 cc). The average length of stay was 7.3 days (range, 4-22 days). Clinical follow-up reported 21 patients (58.3%) with no or minimal pain. There were six deaths during the follow-up unrelated to the index procedure. Radiographic follow-up revealed three patients (8.3%) with rod fracture; one patient with one rod fracture, and two patients with two rod fractures. No patient had three or all four rod fractures. There were no screw fractures. None of the patients with rod fractures required revision surgery. CONCLUSIONS: The biggest advantage of the dual construct is that rod breakage, although uncommon, is typically minimal, or asymptomatic, and more importantly does not result in loss of alignment, and therefore has not required revision surgery. The dual construct approach is a safe alternative to traditional two-rod constructs, with encouraging outcomes at follow-up.

Retrospective analysis underestimates neurological deficits in complex spinal deformity surgery: a Scoli-RISK-1 Study.

OBJECTIVE The authors conducted a study to compare neurological deficit rates associated with complex adult spinal deformity (ASD) surgery when recorded in retrospective and prospective studies. Retrospective studies may underreport neurological deficits due to selection, detection, and recall biases. Prospective studies are expensive and more difficult to perform, but they likely provide more accurate estimates of new neurological deficit rates. METHODS New neurological deficits were recorded in a prospective study of complex ASD surgeries (pSR1) with a defined outcomes measure (decrement in American Spinal Injury Association lower-extremity motor score) for neurological deficits. Using identical inclusion criteria and a subset of participating surgeons, a retrospective study was created (rSR1) and neurological deficit rates were collected. Continuous variables were compared with the Student t-test, with correction for multiple comparisons. Neurological deficit rates were compared using the Mantel-Haenszel method for standardized risks. Statistical significance for the primary outcome measure was p < 0.05. RESULTS Overall, 272 patients were enrolled in pSR1 and 207 patients were enrolled in rSR1. Inclusion criteria, defining complex spinal deformities, and exclusion criteria were identical. Sagittal Cobb measurements were higher in pSR1, although sagittal alignment was similar. Preoperative neurological deficit rates were similar in the groups. Three-column osteotomies were more common in pSR1, particularly vertebral column resection. New neurological deficits were more common in pSR1 (pSR1 17.3% [95% CI 12.6-22.2] and rSR1 9.0% [95% CI 5.0-13.0]; p = 0.01). The majority of deficits in both studies were at the nerve root level, and the distribution of level of injury was similar. CONCLUSIONS New neurological deficit rates were nearly twice as high in the prospective study than the retrospective study with identical inclusion criteria. These findings validate concerns regarding retrospective cohort studies and confirm the need for and value of carefully designed prospective, observational cohort studies in ASD.

Spinal subdural abscess following repeat lumbar microdiscectomy: A case report of imaging findings for a rare infection.

Spinal subdural abscess is a rare central nervous system infection with just over a hundred cases reported. It is much less common than spinal epidural abscess. While most case reports have focused on route of infection and treatment options, there have not been any reports that focused on the unique MRI findings of spinal subdural abscess. We describe a case of spinal subdural abscess diagnosed by MRI in a 33-year-old male who presented with headaches after undergoing a microdiscectomy procedure, and review the underlying anatomic features of the spinal meninges which produce the appearance of a spinal subdural abscess.

Anatomy of Lamina in the Subaxial Cervical Spine With the Special Reference to Translaminar Screws: CT and Cadaveric Analysis With Screw Trajectory Simulation.

STUDY DESIGN: A cadaveric study. SUMMARY OF BACKGROUND DATA: Translaminar screws were initially developed for C2 fixation. Since then, their usage has expanded to include the subaxial cervical spine, and thoracic and lumbar spine. To the best of our knowledge, special anatomy for inserting translaminar screws in the subaxial cervical spine has not been studied. OBJECTIVE: To report the special anatomy for inserting translaminar screws in the subaxial cervical spine. METHODS: A total of 18 cadaveric spines were harvested from C3 to C7 and 1 mm computed tomography (CT) scans and 3D reconstructions were obtained. Bilateral translaminar screw entry points and trajectories were simulated at each level from C3 to C7 utilizing Kodak Carestream/Pacs Ver 10.2. Constructs were selected to achieve maximal bony purchase with 1 screw, designated the "primary screw." The contralateral screw, designated the "secondary screw," was selected to achieve the optimal allowable diameter possible while avoiding a simulated cortical breach, which was not always necessarily the "best purchase" diameter. Initial screw diameters selected were 3.5 mm; however, in the event that a narrower portion was encountered, then a 3.0 mm diameter screw was utilized instead. The crossing area of both screws were calculated geometrically. Maximal thickness of the lamina was considered in determining the diameter of screws. Whenever possible, 3.5 mm screws were selected in both lamina (3.5/3.5 mm); however, if a 3.5 mm screw was utilized as the primary screw, but the permissible range (P) for the secondary screw was <3.5 mm, then a hybrid construct was utilized (3.5/3.0 mm). In cases where P was <3 mm, then both screws were studied at 3 mm (3.0/3.0 mm). Screw diameters that optimized trajectory and bony purchase, while remaining within the permissible range, were analyzed, tabulated, and recorded. On CT, along the trajectory of the screws, the image was cut and measured in terms of screw length, the narrowest portion of the lamina, vertical angle, and horizontal angle in both primary and secondary screws. On the individually separated cervical spine segments in cadavers (11 of 18), we performed caliper measurements on the same portions that were measured on CT. It could not be exactly the same portions, however, due to the 3-dimensional characteristics of the specimens. RESULTS: For C3, only 1 specimen allowed 2 screws (3/3 mm), while the remaining specimens permitted a unilateral primary screw (3.5 or 3 mm) only. For C4, 37% of specimens allowed 2 screws (3.5/3 mm or 3/3 mm), but the rest allowed only a unilateral primary screw (3.5 or 3 mm). For C5, 58% allowed 2 screws (3.5/3.5, 3.5/3, or 3/3 mm). For C6, 89% of specimen allowed 2 screws (3.5/3.5, 3.5/3, or 3/3 mm). For C7, all levels allowed 2 screws (3.5/3.5, 3.5/3, 4/4, 4/3, 4.5/3, 4.5/3.5, or 4/3.5 mm). On CT, the average lengths of the 1- and 2-degree screws were 26.14 and 24.01 mm, respectively. The average vertical and horizontal angles were 22.26 and 40.66 degrees for the 1-degree screw, and 3.45 and 45.59 degrees for the 2-degree screw. On cadavers, the average lengths of the 1- and the 2-degree screws were 22.58 and 23.44 mm, respectively. The average vertical and horizontal angles were 23.67 and 54.44 degrees for the 1-degree screw, and 2.28 and 54.89 degrees for the 2-degree screw. CONCLUSIONS: This is a report of the anatomy of the lamina in the subaxial cervical spine with the special reference to translaminar screws. It was analyzed with CT and cadaveric spines along with simulated screw trajectories. For the 1-degree translaminar screw, the entry point is the distance of the diameter of desired screw superior to the inferior margin of lamina-spinous process junction. The trajectory should be targeted toward the most superomedial corner of lateral mass. For the 2-degree translaminar screw, the entry point is the distance of the diameter of desired screw below the superior margin of lamina-spinous process junction, and the target is the most superolateral corner of lateral mass, which is typically horizontal. Further studies are needed to assess the feasibility of translaminar screw insertion in the actual subaxial cervical spine.

A Comparison of Anterior and Posterior Lumbar Interbody Fusions: Complications, Readmissions, Discharge Dispositions, and Costs.

STUDY DESIGN: Retrospective database review. OBJECTIVE: To understand medical complication rates, readmission rates, costs, and discharge dispositions in anterior lumbar interbody fusion (ALIFs) versus transforaminal lumbar interbody fusions (TLIFs)/posterior lumbar interbody fusions (PLIFs) for lumbar degenerative disease. SUMMARY OF BACKGROUND DATA: Indications for ALIFs versus PLIFs can vary, though benefits of anterior approach surgery include full access to the anterior column and ability to place fusion devices. METHODS: The PearlDiver Database of Medicare records was utilized for this retrospective database review. A study group consisting solely of ALIF procedure patients was selected for. Similarly, a TLIF/PLIF group was selected for. Both groups were queried for comorbidities, 30 and 90-day complication and readmission rates. Additionally, discharge dispositions, and in-hospital/30-day/90-day Medicare reimbursements were determined. RESULTS: At both 30 and 90 days postoperatively odds of ileus, wound infection, and lower extremity deep venous thrombosis were significantly increased in the ALIF. However, unadjusted rates and adjusted odds of transfusion or dural tear were significantly decreased in the ALIF patients. Odds of 30-day readmission were 4 times higher in ALIF patients. Additionally, 30 and 90-day total costs of care in ALIF patients were significantly increased by approximately $4800 and $5800 respectively, as compared with patients undergoing TLIF/PLIF. CONCLUSION: Despite higher initial routine discharge rates, readmissions and costs of postoperative care were significantly increased in ALIF procedures. It is necessary to evaluate etiology of degenerative pathology as ALIFs are successful solutions to anterior translational instability and anterior disc slippage, but may not have the best long-term outcomes and may not be cost-effective compared with a TLIF/PLIF. In light of our data, it is important to assess the risks and benefits of the varying approaches, and the necessity to access the anterior column, when deciding on surgical technique to treat lumbar degenerative pathology. LEVEL OF EVIDENCE: 4.

Cost Implications of Primary Versus Revision Surgery in Adult Spinal Deformity.

BACKGROUND: Adult spinal deformity (ASD) is an important problem to consider in the elderly. Although studies have examined the complications of ASD surgery and have compared functional and radiographic results of primary surgery versus revision, no studies have compared the costs of primary procedures with revisions. We assessed the in-hospital costs of these 2 surgery types in patients with ASD. METHODS: The PearlDiver Database, a database of Medicare records, was used in this study. Mutually exclusive groups of patients undergoing primary or revision surgery were identified. Patients in each group were queried for age, sex, and comorbidities. Thirty-day readmission rates, 30-day and 90-day complication rates, and postoperative costs of care were assessed with multivariate analysis. For analyses, significance was set at P < 0.001. RESULTS: The average reimbursement of the primary surgery cohort was $57,078 ± $30,767. Reimbursement of revision surgery cohort was $52,999 ± $27,658. The adjusted difference in average costs between the 2 groups is $4773 ± $1069 (P < 0.001). The 30-day and 90-day adjusted difference in cost of care when sustaining any of the major medical complications in primary surgery versus revision surgery was insignificant. CONCLUSIONS: Patients undergoing primary and revision corrective procedures for ASD have similar readmission rates, lengths of stays, and complication rates. Our data showed a higher cost of primary surgery compared with revision surgery, although costs of sustaining postoperative complications were similar. This finding supports the decision to perform revision procedures in patients with ASD when indicated because neither outcomes nor costs are a hindrance to correction.

Complications after Fusion for Thoracolumbar Fractures in Patients with Ankylosing Spondylitis.

STUDY DESIGN: Retrospective analysis of a Medicare database (2005 to 2012). OBJECTIVE: To study postoperative complication rates following thoracolumbar fusion for traumatic thoracolumbar fracture in patients with ankylosing spondylitis (AS) compared with patients without AS. METHODS: The PearlDiver database (2005 to 2012) was queried to examine postoperative complication rates in patients with AS undergoing posterior thoracolumbar fusion for thoracolumbar fracture (n = 968). Complication rates were compared with proportion-matched controls without AS undergoing the same procedure (n = 1,979). We examined and compared the incidence of death, postoperative infection, transfusion, venous thromboembolism, respiratory failure, pneumonia, myocardial infarction, urinary tract infection, and acute renal failure in each cohort within 90 days postoperatively. RESULTS: Patients with AS had significantly higher rates of surgical site infection (odds ratio [OR] 1.6, 95% confidence interval [CI] 1.2 to 2.2, p = 0.002), day-of-surgery transfusion rates (OR 1.5, 95% CI 1.3 to 1.8, p < 0.0001), respiratory failure (OR 1.8, 95% CI 1.3 to 2.5, p = 0.0006), pneumonia (OR 1.8, 95% CI 1.3 to 2.5, p = 0.0002), acute renal failure (OR 1.6, 95% CI 1.2 to 2.3, p = 0.005), and total medical complications (OR 1.5, 95% CI 1.2 to 1.9, p < 0.0001). Ninety-day mortality was not different between the two cohorts (p = 0.18). CONCLUSIONS: Thoracolumbar fusion for thoracolumbar fracture in patients with AS is associated with increased rates of surgical site infection, transfusion, respiratory failure, pneumonia, and acute renal failure postoperatively compared with patients without AS. The level of evidence in this study was III.

Complications and Mortality Following One to Two-Level Anterior Cervical Fusion for Cervical Spondylosis in Patients Above 80 Years of Age.

STUDY DESIGN: A retrospective database review. OBJECTIVE: The aim of this study was to determine the complication and mortality rates in patients 80 years of age and older who were treated with anterior cervical fusion surgery and to compare these rates against those of other elderly patients. SUMMARY OF BACKGROUND DATA: Cervical spondylosis is frequently observed in the elderly and is the most common cause of myelopathy in older adults. With increasing life expectancies, a greater proportion of patients are being treated with spine surgery at a later age. Limited information is available regarding outcomes following anterior cervical fusion surgery in patients 80 years of age or older. METHODS: Medicare data from the PearlDiver Database (2005-2012) were queried for patients who underwent primary one to two-level anterior cervical spine fusion surgeries for cervical spondylosis. After excluding patients with prior spine metastasis, bone cancer, spine trauma, or spine infection, this cohort was divided into two study groups: patients 65 to 79 (51,808) and ≥80 years old (5515) were selected. A cohort of matched control patients was selected from the 65 to 79-year-old and 90-day complication rates and 90-day and 1-year mortality rates were compared between cohorts. RESULTS: The proportion of patients experiencing at least one major medical complication was relatively increased by 53.4% in patients aged ≥80 years [odds ratio (OR) 1.63]. Patients 80 years of age or older were more likely to experience dysphagia (OR 2.16), reintubation (OR 2.34), and aspiration pneumonitis (OR 3.17). Both 90-day (OR: 4.34) and 1-year (OR 3.68) mortality were significantly higher in the ≥80 year cohort. CONCLUSION: Patients 80 years of age or older are more likely to experience a major medical complication or mortality following anterior cervical fusion for cervical spondylosis than patients 65 to 79 years old. Dysphagia, aspiration pneumonitis, and reintubation rates are also significantly higher in patients 80 years of age or older. Although complication rates may be higher in this patient population, carefully selected patients could potentially derive much benefit from surgery and should not be screened out solely on the basis of age. LEVEL OF EVIDENCE: 4.