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Kalil G. Abdullah, Edward C. Benzel, and Thomas E. Mroz

Comparative effectiveness research (CER) has impending significance for the field of spine surgery. This article outlines the rationale for comparative effectiveness research and reviews recommended priorities of spinal surgery emphasis. It also examines recent key studies of CER in the spine surgery literature and associated cost-effectiveness studies. It concludes with a discussion of the direction of CER in the spine surgery community.

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Chinmaya Dash, Kanwaljeet Garg, and Shashank S. Kale

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Fraser Henderson Jr., Kalil G. Abdullah, Ragini Verma, and Steven Brem

The ability of diffusion tensor MRI to detect the preferential diffusion of water in cerebral white matter tracts enables neurosurgeons to noninvasively visualize the relationship of lesions to functional neural pathways. Although viewed as a research tool in its infancy, diffusion tractography has evolved into a neurosurgical tool with applications in glioma surgery that are enhanced by evolutions in crossing fiber visualization, edema correction, and automated tract identification. In this paper the current literature supporting the use of tractography in brain tumor surgery is summarized, highlighting important clinical studies on the application of diffusion tensor imaging (DTI) for preoperative planning of glioma resection, and risk assessment to analyze postoperative outcomes. The key methods of tractography in current practice and crucial white matter fiber bundles are summarized. After a review of the physical basis of DTI and post-DTI tractography, the authors discuss the methodologies with which to adapt DT image processing for surgical planning, as well as the potential of connectomic imaging to facilitate a network approach to oncofunctional optimization in glioma surgery.

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Kalil G. Abdullah, Daniel Lubelski, Paolo G. P. Nucifora, and Steven Brem

Diffusion tensor imaging (DTI) is increasingly used in the resection of both high- and low-grade gliomas. Whereas conventional MRI techniques provide only anatomical information, DTI offers data on CNS connectivity by enabling visualization of important white matter tracts in the brain. Importantly, DTI allows neurosurgeons to better guide their surgical approach and resection. Here, the authors review basic scientific principles of DTI, include a primer on the technology and image acquisition, and outline the modality's evolution as a frequently used tool for glioma resection. Current literature supporting its use is summarized, highlighting important clinical studies on the application of DTI in preoperative planning for glioma resection, preoperative diagnosis, and postoperative outcomes. The authors conclude with a review of future directions for this technology.

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Kalil G. Abdullah, Mark A. Attiah, Andrew S. Olsen, Andrew Richardson, and Timothy H. Lucas

OBJECT

Although the use of topical vancomycin has been shown to be safe and effective for reducing postoperative infection rates in patients after spine surgery, its use in cranial wounds has not been studied systematically. The authors hypothesized that topical vancomycin, applied in powder form directly to the subgaleal space during closure, would reduce cranial wound infection rates.

METHODS

A cohort of 150 consecutive patients who underwent craniotomy was studied retrospectively. Seventy-five patients received 1 g of vancomycin powder applied in the subgaleal space at the time of closure. This group was compared with 75 matched-control patients who were accrued over the same time interval and did not receive vancomycin. The primary outcome measure was the presence of surgical site infection within 3 months. Secondary outcome measures included tissue pH from a subgaleal drain and vancomycin levels from the subgaleal space and serum.

RESULTS

Vancomycin was associated with significantly fewer surgical site infections (1 of 75) than was standard antibiotic prophylaxis alone (5 of 75; p < 0.05). Cultures were positive for typical skin flora species. As expected, local measured vancomycin concentrations peaked immediately after surgery (mean ± SD 499 ± 37 μg/ml) and gradually decreased over 12 hours. Vancomycin in the circulating serum remained undetectable. Subgaleal topical vancomycin was associated with a lower incidence of surgical site infections after craniotomy. The authors attribute this reduction in the infection rate to local vancomycin concentrations well above the minimum inhibitory concentration for antimicrobial efficacy.

CONCLUSIONS

Topical vancomycin is safe and effective for reducing surgical site infections after craniotomy. These data support the need for a prospective randomized examination of topical vancomycin in the setting of cranial surgery.

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Kalil G. Abdullah, Amy S. Nowacki, Michael P. Steinmetz, Jeffrey C. Wang, and Thomas E. Mroz

Object

The C-7 lateral mass has been considered difficult to fit with instrumentation because of its unique anatomy. Of the methods that exist for placing lateral mass screws, none particularly accommodates this anatomical variation. The authors have related 12 distinct morphological measures of the C-7 lateral mass to the ability to place a lateral mass screw using the Magerl, Roy-Camille, and a modified Roy-Camille method.

Methods

Using CT scans, the authors performed virtual screw placement of lateral mass screws at the C-7 level in 25 male and 25 female patients. Complications recorded included foraminal and articular process violations, inability to achieve bony purchase, and inability to place a screw longer than 6 mm. Violations were monitored in the coronal, axial, and sagittal planes. The Roy-Camille technique was applied starting directly in the middle of the lateral mass, as defined by Pait's quadrants, with an axial angle of 15° lateral and a sagittal angle of 90°. The Magerl technique was performed by starting in the inferior portion of the top right square of Pait's quadrants and angling 25° laterally in the axial plane with a 45° cephalad angle in the sagittal plane. In a modified method, the starting point is similar to the Magerl technique in the top right square of Pait's quadrant and then angling 15° laterally in the axial plane. In the sagittal plane, a 90° angle is taken perpendicular to the dorsal portion of the lateral mass, as in the traditional Roy-Camille technique.

Results

Of all the morphological methods analyzed, only a combined measure of intrusion of the T-1 facet and the overall length of the C-7 lateral mass was statistically associated with screw placement, and only in the Roy-Camille technique. Use of the Magerl technique allowed screw placement in 28 patients; use of the Roy-Camille technique allowed placement in 24 patients; and use of the modified technique allowed placement in 46 patients. No screw placement by any method was possible in 4 patients.

Conclusions

There is only one distinct anatomical ratio that was shown to affect lateral mass screw placement at C-7. This ratio incorporates the overall length of the lateral mass and the amount of space occupied by the T-1 facet at C-7. Based on this virtual study, a modified Roy-Camille technique that utilizes a higher starting point may decrease the complication rate at C-7 by avoiding placement of the lateral mass screw into the T1 facet.

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Yumeng Li, Daniel Lubelski, Kalil G. Abdullah, Thomas E. Mroz, and Michael P. Steinmetz

Object

Bertolotti's syndrome consists of low-back pain caused by lumbosacral transitional vertebrae (LSTVs) and LSTV-associated biomechanical spinal changes. There is a lack of consensus regarding the cause, clinical significance, and treatment of this condition. The authors aim to characterize the clinical presentation of patients with Bertolotti's syndrome and describe a minimally invasive surgical treatment for this condition.

Methods

Seven patients who underwent minimally invasive paramedian tubular-based resection of the LSTV for Bertolotti's syndrome were identified over the course of 5 years. Diagnosis was based on patient history of chronic low-back pain, radiographic findings of LSTV, and pain relief on trigger-site injection with steroid and/or anesthetics. Electronic medical records were reviewed to identify demographics, operative data, and outcomes.

Results

All patients presented with severe, chronic low-back pain lasting an average of 8 years that was resistant to nonoperative care. At presentation, 6 (86%) of 7 patients experienced radicular pain that was ipsilateral to the LSTV. Radiographic evidence showed a presence of LSTV in all patients on the left (43%), right (29%), or bilaterally (29%). Degenerative disc changes at the L4–5 level immediately above the anomalous LSTV were observed in 6 of 7 (86%) patients; these changes were not seen at the level below the LSTV. Following pseudo-joint injection, all patients experienced temporary relief of their symptoms. All patients underwent a minimally invasive, paramedian tubular-based approach for resection of the LSTV. Three (43%) of 7 patients reported complete resolution of low-back pain, 2 (29%) of 7 patients had reduced low-back pain, and 2 patients (29%) experienced initial relief but return of low-back pain at 1 and 4 years postoperatively. Three (50%) of the 6 patients with radicular pain had complete relief of this symptom. The median follow-up time was 12 months. No intraoperative complication was reported. Two (29%) of 7 patients developed postoperative complications including one with a wound hematoma and another with new L-5 radiculopathy that resolved 2 years after surgery.

Conclusions

Diagnosis of Bertolotti's syndrome should be considered with adequate patient history, imaging studies, and diagnostic injections. A minimally invasive surgical approach for resection of the LSTV is presented here for symptomatic treatment of select patients with Bertolotti's syndrome whose conditions are refractory to conventional therapy and who have pain that can be attributed to the LSTV. Several short-term complications were noted with this procedure, but overall this procedure is effective for treating symptoms related to Bertolotti's syndrome.

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Matthew D. Alvin, Jacob A. Miller, Daniel Lubelski, Benjamin P. Rosenbaum, Kalil G. Abdullah, Robert G. Whitmore, Edward C. Benzel, and Thomas E. Mroz

Object

Cost-effectiveness research in spine surgery has been a prominent focus over the last decade. However, there has yet to be a standardized method developed for calculation of costs in such studies. This lack of a standardized costing methodology may lead to conflicting conclusions on the cost-effectiveness of an intervention for a specific diagnosis. The primary objective of this study was to systematically review all cost-effectiveness studies published on spine surgery and compare and contrast various costing methodologies used.

Methods

The authors performed a systematic review of the cost-effectiveness literature related to spine surgery. All cost-effectiveness analyses pertaining to spine surgery were identified using the cost-effectiveness analysis registry database of the Tufts Medical Center Institute for Clinical Research and Health Policy, and the MEDLINE database. Each article was reviewed to determine the study subject, methodology, and results. Data were collected from each study, including costs, interventions, cost calculation method, perspective of cost calculation, and definitions of direct and indirect costs if available.

Results

Thirty-seven cost-effectiveness studies on spine surgery were included in the present study. Twenty-seven (73%) of the studies involved the lumbar spine and the remaining 10 (27%) involved the cervical spine. Of the 37 studies, 13 (35%) used Medicare reimbursements, 12 (32%) used a case-costing database, 3 (8%) used cost-to-charge ratios (CCRs), 2 (5%) used a combination of Medicare reimbursements and CCRs, 3 (8%) used the United Kingdom National Health Service reimbursement system, 2 (5%) used a Dutch reimbursement system, 1 (3%) used the United Kingdom Department of Health data, and 1 (3%) used the Tricare Military Reimbursement system. Nineteen (51%) studies completed their cost analysis from the societal perspective, 11 (30%) from the hospital perspective, and 7 (19%) from the payer perspective. Of those studies with a societal perspective, 14 (38%) reported actual indirect costs.

Conclusions

Changes in cost have a direct impact on the value equation for concluding whether an intervention is cost-effective. It is essential to develop a standardized, accurate means of calculating costs. Comparability and transparency are essential, such that studies can be compared properly and policy makers can be appropriately informed when making decisions for our health care system based on the results of these studies.

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Daniel Lubelski, James Feghali, Amy S. Nowacki, Vincent J. Alentado, Ryan Planchard, Kalil G. Abdullah, Daniel M. Sciubba, Michael P. Steinmetz, Edward C. Benzel, and Thomas E. Mroz

OBJECTIVE

Patient demographics, comorbidities, and baseline quality of life (QOL) are major contributors to postoperative outcomes. The frequency and cost of lumbar spine surgery has been increasing, with controversy revolving around optimal management strategies and outcome predictors. The goal of this study was to generate predictive nomograms and a clinical calculator for postoperative clinical and QOL outcomes following lumbar spine surgery for degenerative disease.

METHODS

Patients undergoing lumbar spine surgery for degenerative disease at a single tertiary care institution between June 2009 and December 2012 were retrospectively reviewed. Nomograms and an online calculator were modeled based on patient demographics, comorbidities, presenting symptoms and duration of symptoms, indication for surgery, type and levels of surgery, and baseline preoperative QOL scores. Outcomes included postoperative emergency department (ED) visit or readmission within 30 days, reoperation within 90 days, and 1-year changes in the EuroQOL-5D (EQ-5D) score. Bootstrapping was used for internal validation.

RESULTS

A total of 2996 lumbar surgeries were identified. Thirty-day ED visits were seen in 7%, 30-day readmission in 12%, 90-day reoperation in 3%, and improvement in EQ-5D at 1 year that exceeded the minimum clinically important difference in 56%. Concordance indices for the models predicting ED visits, readmission, reoperation, and dichotomous 1-year improvement in EQ-5D were 0.63, 0.66, 0.73, and 0.84, respectively. Important predictors of clinical outcomes included age, body mass index, Charlson Comorbidity Index, indication for surgery, preoperative duration of symptoms, and the type (and number of levels) of surgery. A web-based calculator was created, which can be accessed here: https://riskcalc.org/PatientsEligibleForLumbarSpineSurgery/.

CONCLUSIONS

The prediction tools derived from this study constitute important adjuncts to clinical decision-making that can offer patients undergoing lumbar spine surgery realistic and personalized expectations of postoperative outcome. They may also aid physicians in surgical planning, referrals, and counseling to ultimately lead to improved patient experience and outcomes.

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Daniel Lubelski, Kalil G. Abdullah, Amy S. Nowacki, Matthew D. Alvin, Michael P. Steinmetz, Srita Chakka, Yumeng Li, Nicholas Gajewski, Edward C. Benzel, and Thomas E. Mroz

Object

The goal of this study was to compare the urological complications in patients after anterior lumbar interbody fusion (ALIF) with and without the use of recombinant human bone morphogenetic protein–2 (rhBMP-2).

Methods

The authors retrospectively reviewed the medical records of all patients who underwent ALIF with and without rhBMP-2 between January 2002 and August 2010. Patient demographic, operative, and complication information was analyzed. Male patients who underwent ALIF between L-4 and S-1 were contacted to assess postoperative urological complications.

Results

Of the 110 male patients who underwent ALIF and were included in this study, 59 were treated with rhBMP-2 and 51 did not receive rhBMP-2. The mean follow-up duration was 17.5 months for the rhBMP-2 group and 30.8 months for the control group. No difference was found regarding the total number of urological complications in the rhBMP-2 group versus the control group (22% vs 20%, respectively; p = 1.0) or for retrograde ejaculation specifically (8% vs 8%, respectively; p = 1.0).

Conclusions

In this study, the use of rhBMP-2 with ALIF surgery was not associated with an increased incidence of urological complications and retrograde ejaculation when compared with control ALIF without rhBMP-2. Further prospective analyses that specifically look at these complications are warranted.