Roger Härtl

Cornell University, Ithaca, NY, United States

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Publications (64)140.1 Total impact

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    ABSTRACT: Object Anterior cervical plating decreases the risk of pseudarthrosis following anterior cervical discectomy and fusion (ACDF). Dysphagia is a common complication of ACDF, with the anterior plate implicated as a potential contributor. A zero-profile, stand-alone polyetheretherketone (PEEK) interbody spacer has been postulated to minimize soft-tissue irritation and postoperative dysphagia, but studies are limited. The object of the present study was to determine the clinical and radiological outcomes for patients who underwent ACDF using a zero-profile integrated plate and spacer device, with a focus on the course of postoperative prevertebral soft-tissue thickness and the incidence of dysphagia. Methods Using a surgical database, the authors conducted a retrospective analysis of all patients who had undergone ACDF between August 2008 and October 2011. All patients received a Zero-P implant (DePuy Synthes Spine). The Neck Disability Index (NDI) and visual analog scale (VAS) scores for arm and neck pain were documented. Dysphagia was determined using the Bazaz criteria. Prevertebral soft-tissue thickness, spinal alignment, and subsidence were assessed as well. Results Twenty-two male and 19 female consecutive patients, with a mean age of 58.4 ± 14.68, underwent ACDF (66 total operated levels) in the defined study period. The mean clinical follow-up in 36 patients was 18.6 ± 9.93 months. Radiological outcome in 37 patients was assessed at a mean follow-up of 9.76 months (range 7.2-19.7 months). There were significant improvements in neck and arm VAS scores and the NDI following surgery. The neck VAS score improved from a median of 6 (range 0-10) to 0 (range 0-8; p < 0.001). The arm VAS score improved from a median of 2 (range 0-10) to 0 (range 0-7; p = 0.006). Immediate postoperative dysphagia was experienced by 58.4% of all patients. Complete resolution was demonstrated in 87.8% of affected patients at the latest follow-up. The overall median Bazaz score decreased from 1 (range 0-3) immediately postoperatively to 0 (range 0-2; p < 0.001) at the latest follow-up. Prevertebral soft-tissue thickness significantly decreased across all levels from a mean of 15.8 ± 4.38 mm to 10.1 ± 2.93 mm. Postoperative lordosis was maintained at the latest follow-up. Mean subsidence from the immediate postoperative to the latest follow-up was 4.1 ± 4.7 mm (p < 0.001). Radiographic fusion was achieved in 92.6% of implants. No correlation was found between prevertebral soft-tissue thickness and Bazaz dysphagia score. Conclusions A zero-profile integrated plate and spacer device for ACDF surgery produces clinical and radiological outcomes that are comparable to those for nonintegrated plate and spacer constructs. Chronic dysphagia rates are comparable to or better than those for previously published case series.
    Journal of neurosurgery. Spine. 08/2014;
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    ABSTRACT: Object Extreme lateral interbody fusion (ELIF) is a popular technique for anterior fixation of the thoracolumbar spine. Clinical and radiological outcome studies are required to assess safety and efficacy. The aim of this study was to describe the functional and radiological impact of ELIF in a degenerative disc disease population with a longer follow-up and to assess the durability of this procedure. Methods Demographic and perioperative data for all patients who had undergone ELIF for degenerative lumbar disorders between 2007 and 2011 were collected. Trauma and tumor cases were excluded. For radiological outcome, the preoperative, immediate postoperative, and latest follow-up coronal Cobb angle, lumbar sagittal lordosis, bilateral foraminal heights, and disc heights were measured. Pelvic incidence (PI) and PI-lumbar lordosis (PI-LL) mismatch were assessed in scoliotic patients. Clinical outcome was evaluated using the Oswestry Disability Index (ODI) and visual analog scale (VAS), as well as the Macnab criteria. Results One hundred forty-five vertebral levels were surgically treated in 90 patients. Pedicle screw and rod constructs and lateral plates were used to stabilize fixation in 77% and 13% of cases, respectively. Ten percent of cases involved stand-alone cages. At an average radiological follow-up of 12.6 months, the coronal Cobb angle was 10.6° compared with 23.8° preoperatively (p < 0.0001). Lumbar sagittal lordosis increased by 5.3° postoperatively (p < 0.0001) and by 2.9° at the latest follow-up (p = 0.014). Foraminal height and disc height increased by 4 mm (p < 0.0001) and 3.3 mm (p < 0.0001), respectively, immediately after surgery and remained significantly improved at the last follow-up. Separate evaluation of scoliotic patients showed no statistically significant improvement in PI and PI-LL mismatch either immediately postoperatively or at the latest follow-up. Clinical evaluation at an average follow-up of 17.6 months revealed an improvement in the ODI and the VAS scores for back, buttock, and leg pain by 21.1% and 3.7, 3.6, and 3.7 points, respectively (p < 0.0001). According to the Macnab criteria, 84.8% of patients had an excellent, good, or fair functional outcome. New postoperative thigh numbness and weakness was detected in 4.4% and 2.2% of the patients, respectively, which resolved within the first 3 months after surgery in all but 1 case. Conclusions This study provides what is to the authors' knowledge the most comprehensive set of radiological and clinical outcomes of ELIF in a fairly large population at a midterm follow-up. Extreme lateral interbody fusion showed good clinical outcomes with a low complication rate. The procedure allows for at least midterm clinically effective restoration of disc and foraminal heights. Improvement in coronal deformity and a small but significant increase in sagittal lordosis were observed. Nonetheless, no significant improvement in the PI-LL mismatch was achieved in scoliotic patients.
    Journal of neurosurgery. Spine 04/2014; · 1.61 Impact Factor
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    ABSTRACT: Radiculopathy caused by foraminal nerve root compression is a common pathology in the lumbar spine. Surgical decompression via a conventional open foraminotomy is the treatment of choice when surgery is indicated. Minimally invasive tubular foraminotomy through a contralateral approach is a potentially effective surgical alternative. The aim of this retrospective cohort study was to evaluate the efficacy and benefits of this approach for treatment of radiculopathy. Patients with unilaterally dominant lower extremity radiculopathy, who underwent minimally invasive lumbar foraminotomy through tubular retractors via a contralateral approach between 2010 and 2012, were included. Oswestry Disability Index (ODI) and the Visual Analogue Scale (VAS) for back and leg pain were evaluated pre-operatively, post-operatively, and at the latest follow-up. Functional outcome was evaluated using MacNab's criteria. For the total 32 patients, post-operatively there was significant improvement in the ODI (p=0.006), VAS back pain (p<0.0001), and VAS leg pain on the pathology and the approach side (p = 0.004, p=0.021, respectively). At follow-up of 12.3 ± 1.7 months, there was also significant improvement in the ODI (p<0.0001), VAS back pain (p=0.001), and VAS leg pain on the pathology and the approach side (p<0.0001, p = 0.001, respectively). The functional outcome was excellent and good in 95.2%. One patient required fusion (3.1%). A minimally invasive, facet-sparing contralateral approach is an effective technique for treatment of radiculopathy due to foraminal compression. It also allows for decompression of lumbar spinal stenosis and bilateral lateral recess decompression without the need for fusion.
    Neurosurgery 03/2014; · 2.53 Impact Factor
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    ABSTRACT: Object Tissue-engineered intervertebral discs (TE-IVDs) represent a new experimental approach for the treatment of degenerative disc disease. Compared with mechanical implants, TE-IVDs may better mimic the properties of native discs. The authors conducted a study to evaluate the outcome of TE-IVDs implanted into the rat-tail spine using radiological parameters and histology. Methods Tissue-engineered intervertebral discs consist of a distinct nucleus pulposus (NP) and anulus fibrosus (AF) that are engineered in vitro from sheep IVD chondrocytes. In 10 athymic rats a discectomy in the caudal spine was performed. The discs were replaced with TE-IVDs. Animals were kept alive for 8 months and were killed for histological evaluation. At 1, 5, and 8 months, MR images were obtained; T1-weighted sequences were used for disc height measurements, and T2-weighted sequences were used for morphological analysis. Quantitative T2 relaxation time analysis was used to assess the water content and T1ρ-relaxation time to assess the proteoglycan content of TE-IVDs. Results Disc height of the transplanted segments remained constant between 68% and 74% of healthy discs. Examination of TE-IVDs on MR images revealed morphology similar to that of native discs. T2-relaxation time did not differ between implanted and healthy discs, indicating similar water content of the NP tissue. The size of the NP decreased in TE-IVDs. Proteoglycan content in the NP was lower than it was in control discs. Ossification of the implanted segment was not observed. Histological examination revealed an AF consisting of an organized parallel-aligned fiber structure. The NP matrix appeared amorphous and contained cells that resembled chondrocytes. Conclusions The TE-IVDs remained viable over 8 months in vivo and maintained a structure similar to that of native discs. Tissue-engineered intervertebral discs should be explored further as an option for the potential treatment of degenerative disc disease.
    Journal of neurosurgery. Spine 02/2014; · 1.61 Impact Factor
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    ABSTRACT: Study Design. Animal experimental studyObjective. To evaluate a novel quantitative imaging technique for assessing disc degeneration.Summary of Background Data. T2-relaxation time (T2-RT) measurements have been used to quantitatively assess disc degeneration. T2 values correlate with the water content of inter vertebral disc tissue and thereby allow for the indirect measurement of nucleus pulposus (NP) hydration.Methods. We developed an algorithm to subtract out MRI voxels not representing NP tissue based on T2-RT values. Filtered NP voxels were used to measure nuclear size by their amount and nuclear hydration by their mean T2-RT. This technique was applied to 24 rat-tail intervertebral discs' (IVDs), which had been punctured with an 18-gauge needle according to different techniques to induce varying degrees of degeneration. NP voxel count and average T2-RT were used as parameters to assess the degeneration process at 1 and 3 months post puncture.NP voxel counts were evaluated against X-ray disc height measurements and qualitative MRI studies based on the Pfirrmann grading system.Tails were collected for histology to correlate NP voxel counts to histological disc degeneration grades and to NP cross-sectional area measurements.Results. NP voxel count measurements showed strong correlations to qualitative MRI analyses (R = 0.79, p<0.0001), histological degeneration grades (R = 0.902, p<0.0001) and histological NP cross-sectional area measurements (R = 0.887, p<0.0001).In contrast to NP voxel counts, the mean T2-RT for each punctured group remained constant between months 1 and 3. The mean T2-RTs for the punctured groups did not show a statistically significant difference from those of healthy IVDs (63.55ms ±5.88ms month 1 and 62.61ms ±5.02ms) at either time point.Conclusion. The NP voxel count proved to be a valid parameter to quantitatively assess disc degeneration in a needle puncture model. The mean NP T2-RT does not change significantly in needle-puncture induced degenerated IVDs. IVDs can be segmented into different tissue components according to their innate T2-RT.
    Spine 12/2013; · 2.16 Impact Factor
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    ABSTRACT: Study Design. Animal in vivo study.Objective. To test the capability of high-density collagen gel to repair annular defects.Summary of Background Data. Annular defects are associated with spontaneous disc herniations and disc degeneration, which can lead to significant morbidity. Persistent annular defects following surgical discectomies can increase reherniation rates. Several synthetic and biological materials have been developed for annular repair. This is the first study to test an injectable biomaterial in vivo.Methods. We punctured caudal intervertebral discs in 42 athymic rats, using an 18-gauge needle to create an annular defect. High-density collagen (HDC), either alone or cross-linked with riboflavin (RF), was injected into the defect. There were four separate study groups: HDC, HDC cross-linked with either 0.25mM RF or 0.50mM RF, and a negative control that was punctured and not treated. The animals were followed for five weeks; X-rays were used to assess disc heights and MR imaging to evaluate degenerative changes. We developed an algorithm based on T2-relaxation time measurements to assess the size of the nucleus pulposus (NP). Tails were collected for histological analysis to evaluate disc degeneration and measure the cross-sectional area of the NP.Results. After five weeks, the control and the uncross-linked HDC groups both showed signs of progressive degenerative changes with minimal or no residual NP tissue in the disc space. Cross-linking significantly improved the ability of HDC gels to repair annular defects. The 0.50mM RF cross-linked group showed only a slight decrease in nuclear tissue when compared to healthy discs, with no signs of IVD degeneration. The AF was partially repaired by a fibrous cap that bridged the defect. Host fibroblasts infiltrated and remodeled the injected collagen.Conclusion. HDC is capable of repairing annular defects induced by needle puncture. The stiffness of HDC can be modified by riboflavin cross-linking and appears to positively affect the repair mechanism. These results need to be replicated in a larger animal model.
    Spine 11/2013; · 2.16 Impact Factor
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    ABSTRACT: Object In spite of evidence that use of the Brain Trauma Foundation Guidelines for the Management of Severe Traumatic Brain Injury (Guidelines) would dramatically reduce morbidity and mortality, adherence to these Guidelines remains variable across trauma centers. The authors analyzed 2-week mortality due to severe traumatic brain injury (TBI) from 2001 through 2009 in New York State and examined the trends in adherence to the Guidelines. Methods The authors calculated trends in adherence to the Guidelines and age-adjusted 2-week mortality rates between January 1, 2001, and December 31, 2009. Univariate and multivariate logistic regression analyses were performed to evaluate the effect of time period on case-fatality. Intracranial pressure (ICP) monitor insertion was modeled in a 2-level hierarchical model using generalized linear mixed effects to allow for clustering by different centers. Results From 2001 to 2009, the case-fatality rate decreased from 22% to 13% (p < 0.0001), a change that remained significant after adjusting for factors that independently predict mortality (adjusted OR 0.52, 95% CI 0.39-0.70; p < 0.0001). Guidelines adherence increased, with the percentage of patients with ICP monitoring increasing from 56% to 75% (p < 0.0001). Adherence to cerebral perfusion pressure treatment thresholds increased from 15% to 48% (p < 0.0001). The proportion of patients having an ICP elevation greater than 25 mm Hg dropped from 42% to 29% (p = 0.0001). Conclusions There was a significant reduction in TBI mortality between 2001 and 2009 in New York State. Increase in Guidelines adherence occurred at the same time as the pronounced decrease in 2-week mortality and decreased rate of intracranial hypertension, suggesting a causal relationship between Guidelines adherence and improved outcomes. Our findings warrant future investigation to identify methods for increasing and sustaining adherence to evidence-based Guidelines recommendations.
    Journal of Neurosurgery 10/2013; · 3.15 Impact Factor
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    ABSTRACT: Object The paracoccygeal approach allows for instrumentation of L5/S1 and L4/5 by using a transsacral rod (AxiaLIF; TransS1, Inc.). The authors analyzed clinical and radiographic outcomes of 1- or 2-level AxiaLIF procedures with focus on durability of the construct. Methods This was a retrospective study of 38 consecutive patients who underwent either 1-level (32 patients) or 2-level (6 patients) AxiaLIF procedures at the authors' institution. The Oswestry Disability Index (minimum clinically important difference [MCID] ≥ 12) and visual analog scale ([VAS]; MCID ≥ 3) scores were collected. Disc height and Cobb angles were measured on pre- and postoperative radiographs. Bony fusion was determined on CT scans or flexion/extension radiographs. Results Implantation of a transsacral rod allowed for intraoperative distraction of the L5/S1 intervertebral space and resulted in increased segmental lordosis postoperatively. At a mean follow-up time of 26.2 ± 2.4 months, however, graft subsidence (1.9 mm) abolished partial correction of segmental lordosis. Moreover, subsidence of the construct reduced L5/S1 lordosis in patients with 1-level AxiaLIF by 3.2° and L4-S1 lordosis in patients with 2-level procedures by 10.1° compared with preoperative values (p < 0.01). Loss of segmental lordosis predicted failure to improve VAS scores for back pain in the patient cohort (p < 0.05). Overall, surgical intervention led to modest symptomatic improvement; only 26.3% of patients achieved an MCID of the Oswestry Disability Index and 50% of patients an MCID of the VAS score for back pain. At last follow-up, 71.9% of L5/S1 levels demonstrated bony fusion (1-level AxiaLIF 80.8%, 2-level AxiaLIF 33.3%; p < 0.05), whereas none of the L4/5 levels in 2-level AxiaLIF fused. Five constructs developed pseudarthrosis and required surgical revision. Conclusions The AxiaLIF procedure constitutes a minimally invasive technique for L5/S1 instrumentation, with low perioperative morbidity. However, the axial rod provides inadequate long-term anterior column support, which leads to subsidence and loss of segmental lordosis. Modification of the transsacral technique to allow for placement of a solid interposition graft may counteract subsidence of the construct.
    Journal of neurosurgery. Spine 08/2013; · 1.61 Impact Factor
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    ABSTRACT: In a resource-poor environment such as rural East Africa expensive medical devices such as Ctscanners are rare. The CT-scanner of rural Haydom Lutheran Hospital (HLH) in Tanzania offers therefore a unique chance to observe possible differences with urban medical centers in the disease pattern of trauma-related cranial pathologies. To compare traumatic brain injuries (TBI) between a rural and an urban area of Tanzania. Retrospective Study METHODS: HLH has 350 beds and one computed tomography. The urban Aga Khan Hospital (AKH) is a private hospital with 80 beds and one CT-scanner. Data of 248 patients at HLH and of 432 patients at AKH, who carried a diagnosis of TBI could be collected. The prevalence of TBI was significantly higher in the rural area compared to the urban area (34.2% vs. 21.9%, p<0.0001). TBI due to violence was noted to occur more frequently at HLH, road traffic accidents were more frequent at AKH. The number of patients showing a normal CT-result was significantly higher in the urban area (53.0% vs. 35.9%, p<0.0001). Bone fractures (35.9% vs. 15.7%, p<0.0001) and pneumocephalus (6.9% vs. 0.9%, p<0.0001) were diagnosed significantly more frequently in the rural survey. Soft tissue swelling (11.6% vs. 1.2%, p < 0.0001) and frontal sinus injuries (7.4%vs. 0.4%, p<0.0001) were observed significantly more often in the urban setting. This study documents the burden of TBI and the differences in TBI-related CT diagnoses and their incidence between urban and rural areas in Eastern Africa. These results are important as they demonstrate that patients with severe TBI are not a primarily urban concern. Management of TBI should be included in training curricula for health personnel alike irrespective of whether their work place is primarily urban or rural.
    World Neurosurgery 08/2013; · 1.77 Impact Factor
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    ABSTRACT: Advanced intervertebral disc (IVD) degeneration, a major cause of back pain in the United States, is treated using invasive surgical intervention which may cause further degeneration is the future. Because of the limitations of traditional solutions, tissue engineering therapies have become increasingly popular. IVDs have two distinct regions, the inner nucleus pulposus (NP) which is jelly-like and rich in glycosaminoglycans (GAGs) and the outer annulus fibrosus (AF) which is organized into highly collagenous lamellae. Tissue engineered scaffolds, as well as whole organ culture systems have been developed. These culture systems may help elucidate the initial causes of disc degeneration. To create an effective tissue engineered therapy, researchers have focused on designing materials that mimic the properties of these two regions to be used independently or in concert. The few in vivo studies show promise in retaining disc height and MRI T2 signal intensity, the gold standard in determining disc health.
    Current opinion in biotechnology 06/2013; · 7.82 Impact Factor
  • Journal of neurosurgery. Spine 05/2013; 18(5):530-3. · 1.61 Impact Factor
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    ABSTRACT: Context: Recently, concussion has become a topic of much discussion within sports. The goal of this review is to provide an overview of the literature concerning the definition of concussion, management of initial injury, return to play, and future health risks.
    Sports Health A Multidisciplinary Approach 03/2013; 5(2):160-164.
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    ABSTRACT: Object Three-dimensional spinal navigation increases screw accuracy, but its implementation in clinical practice has been difficult, mainly because of surgeons' concerns about increased operative times, disturbance of workflow, and safety. The authors present a custom-designed navigated guide that addresses some of these concerns by allowing for drilling, tapping, and placing the final screw via a minimally invasive approach without the need for K-wires. In this paper, the authors' goal was to describe the technical aspects of the navigated guide tube as well as pedicle screw accuracy. Methods The authors present the technical details of a navigated guide that allows drilling, tapping, and the placement of the final screw without the need for K-wires. The first 10 patients who received minimally invasive mini-open spinal pedicle screws are presented. The case series focuses on the immediate postoperative outcomes, pedicle screw accuracy, and pedicle screw-related complications. An independent board-certified neuroradiologist determined pedicle screw accuracy according to a 4-tiered grading system. Results The navigated guide allowed successful placement of mini-open pedicle screws as part of posterior fixation from L-1 to S-1 without the use of K-wires. Only 7-mm-diameter screws were placed, and 72% of screws were completely contained within the pedicle. Breaches less than 2 mm were seen in 23% of cases, and these were all lateral except for one screw. Breaches were related to the lateral to medial trajectory chosen to avoid the superior facet joint. There were no complications related to pedicle screw insertion. Conclusions A novel customized navigated guide tube is presented that facilitates the workflow and allows accurate placement of mini-open pedicle screws without the need for K-wires.
    Journal of neurosurgery. Spine 11/2012; · 1.61 Impact Factor
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    ABSTRACT: BACKROUND: The paucity of neurosurgical care in East Africa remains largely unaddressed. A sustained investment in local health infrastructures and staff training is needed to create an independent surgical capacity. The Madaktari organization has addressed this issue by starting initiatives to train local general surgeons and assistant medical officers in basic neurosurgical procedures. We report illustrative cases since beginning of the program in Mwanza in 2009 and focus on the most recent training period. METHODS: A multi-institutional neurosurgical training program and a surgical database was created at a tertiary referral center in Mwanza, Tanzania. We collected clinical data on consecutive patients that underwent a neurosurgical procedure between September 9(th) and December 1(st), 2011. All procedures were performed by a local surgeon under the supervision of a visiting neurosurgeon. Since the inception of the training initiative, comprehensive multidisciplinary training courses in Tanzania and an annual visiting fellowship for East African surgeons to travel to a major US medical center have been established. RESULTS: At initial visits infrastructure and feasibility of complex case scenarios was assessed. Surgeries for brain tumors and complex spinal cases were performed. During the 3-month training period, 62 patients underwent surgery. Pediatric hydrocephalus comprised 52 % of patients, 11% suffered from meningomyelocelia, and 6% presented with an encephalocele. 24% of patients were treated for trauma-related conditions representing 75% of the adult patients. 10% of patients had surgery because of traumatic spine injury, and 15% of operations were on severe head injury patients. 6% of patients presented with degenerative spine disease. One patient sustained a fatal peri-operative complication. At the end of the training period, the local general surgeon was able to perform all basic neurosurgical cases independently. CONCLUSION: Neurosurgical care in Tanzania needs to address a diverse, unique disease burden. We found that local surgeons could be enabled to safely perform basic cranial and spinal neurosurgical proceduresthrough immersive, one-on-one on-site collaborations, multidisciplinary courses, and educational visiting fellowships.
    World Neurosurgery 09/2012; · 1.77 Impact Factor
  • C P Hofstetter, R Härtl
    World Neurosurgery 09/2012; · 1.77 Impact Factor
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    ABSTRACT: Purpose The aim of this study was to assess the impact of 3-D navigation for pedicle screw placement accuracy in minimally invasive transverse lumbar interbody fusion (MIS-TLIF). Methods A retrospective review of 52 patients who had MIS-TLIF assisted with 3D navigation is presented. Clinical outcomes were assessed with the Oswestry Disability Index (ODI), Visual Analog Scales (VAS), and MacNab scores. Radiographic outcomes were assessed using X-rays and thin-slice computed tomography. Result The mean age was 56.5 years, and 172 screws were implanted with 16 pedicle breaches (91.0% accuracy rate). Radiographic fusion rate at a mean follow-up of 15.6 months was 87.23%. No revision surgeries were required. The mean improvement in the VAS back pain, VAS leg pain, and ODI at 11.3 months follow-up was 4.3, 4.5, and 26.8 points, respectively. At last follow-up the mean postoperative disc height gain was 4.92 mm and the mean postoperative disc angle gain was 2.79 degrees. At L5-S1 level, there was a significant correlation between a greater disc space height gain and a lower VAS leg score. Conclusion Our data support that application of 3-D navigation in MIS-TLIF is associated with a high level of accuracy in the pedicle screw placement.
    Global spine journal. 09/2012; 2(3):143-52.
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    ABSTRACT: Object Evidence-based guidelines recommend intracranial pressure (ICP) monitoring for patients with severe traumatic brain injury (TBI), but there is limited evidence that monitoring and treating intracranial hypertension reduces mortality. This study uses a large, prospectively collected database to examine the effect on 2-week mortality of ICP reduction therapies administered to patients with severe TBI treated either with or without an ICP monitor. Methods From a population of 2134 patients with severe TBI (Glasgow Coma Scale [GCS] Score <9), 1446 patients were treated with ICP-lowering therapies. Of those, 1202 had an ICP monitor inserted and 244 were treated without monitoring. Patients were admitted to one of 20 Level I and two Level II trauma centers, part of a New York State quality improvement program administered by the Brain Trauma Foundation between 2000 and 2009. This database also contains information on known independent early prognostic indicators of mortality, including age, admission GCS score, pupillary status, CT scanning findings, and hypotension. Results Age, initial GCS score, hypotension, and CT scan findings were associated with 2-week mortality. In addition, patients of all ages treated with an ICP monitor in place had lower mortality at 2 weeks (p = 0.02) than those treated without an ICP monitor, after adjusting for parameters that independently affect mortality. Conclusions In patients with severe TBI treated for intracranial hypertension, the use of an ICP monitor is associated with significantly lower mortality when compared with patients treated without an ICP monitor. Based on these findings, the authors conclude that ICP-directed therapy in patients with severe TBI should be guided by ICP monitoring.
    Journal of Neurosurgery 08/2012; 117(4):729-34. · 3.15 Impact Factor
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    ABSTRACT: STUDY DESIGN.: Retrospective study. OBJECTIVE.: To assess the clinical and radiographical outcomes in spinal fusion procedures using silicate-substituted calcium phosphate (Si-CaP). SUMMARY OF BACKGROUND DATA.: Si-CaP is a newer-generation synthetic ceramic designed to maximize osteoinduction and osteoconduction. METHODS.: This is a retrospective analysis of a prospectively collected patient database including 108 patients (204 individual spinal levels). Different surgical procedures performed included 25 anterior cervical discectomy and fusions, 17 posterior cervical fusions, 7 combined anterior and posterior cervical fusions, 10 thoracic fusion surgeries, 18 transforaminal lumbar interbody fusions with 12 axial lumbar interbody fusions, 11 transpsoas discectomy and fusions, and 8 combined thoracolumbar fusion procedures. Si-CaP was used as bone extender without any additional graft material, bone marrow aspirate, or bone morphogenetic protein. Clinical outcomes were assessed using the visual analogue scale (VAS), Oswestry Disability Index, and Neck Disability Index. Fusion was determined by the presence of bony bridging on 2 consecutive sections in at least 2 planes on computed tomographic imaging. RESULTS.: At a follow-up of 12 (±4.7) months, 90% of all patients demonstrated radiographical fusion. Fusion rates were highest in the cervical spine (97%) followed by thoracic and lumbar spines (86% and 81%, respectively). There were significant improvements in all clinical outcome measures-Oswestry Disability Index, 11.1 (±10.2) and Neck Disability Index, 9.0 (±11.4); VAS-back, 3.1(±3.0); VAS-leg, 3.5 (±3.6); VAS-neck, 3.7 (±2.5); and VAS-arm 4.0 (±3.2). There was no radiographical loosening of instrumentation due to infection or nonunion in this series, and no subsequent revisions for nonunion were required. CONCLUSION.: Si-CaP is an alternative to autogenous bone graft in spinal arthrodesis procedures. At 12-month follow-up, we detected high levels of bony fusion using Si-CaP in combination with various surgical spinal techniques.
    Spine 06/2012; 37(20):E1264-72. · 2.16 Impact Factor
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    ABSTRACT: In this paper the authors' goal was to compare the accuracy of computer-navigated pedicle screw insertion with nonnavigated techniques in the published literature. The authors performed a systematic literature review using the National Center for Biotechnology Information Database (PubMed/MEDLINE) using the Medical Subject Headings (MeSH) terms "Neuronavigation," "Therapy, computer assisted," and "Stereotaxic techniques," and the text word "pedicle." Included in the meta-analysis were randomized control trials or patient cohort series, all of which compared computer-navigated spine surgery (CNSS) and nonassisted pedicle screw insertions. The primary end point was pedicle perforation, while the secondary end points were operative time, blood loss, and complications. Twenty studies were included for analysis; of which there were 18 cohort studies and 2 randomized controlled trials published between 2000 and 2011. Foreign-language papers were translated. The total number of screws included was 8539 (4814 navigated and 3725 nonnavigated). The most common indications for surgery were degenerative disease, spinal deformity, myelopathy, tumor, and trauma. Navigational methods were primarily based on CT imaging. All regions of the spine were represented. The relative risk for pedicle screw perforation was determined to be 0.39 (p < 0.001), favoring navigation. The overall pedicle screw perforation risk for navigation was 6%, while the overall pedicle screw perforation risk was 15% for conventional insertion. No related neurological complications were reported with navigated insertion (4814 screws total); there were 3 neurological complications in the nonnavigated group (3725 screws total). Furthermore, the meta-analysis did not reveal a significant difference in total operative time and estimated blood loss when comparing the 2 modalities. There is a significantly lower risk of pedicle perforation for navigated screw insertion compared with nonnavigated insertion for all spinal regions.
    Journal of neurosurgery. Spine 06/2012; 17(2):113-22. · 1.61 Impact Factor
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    ABSTRACT: OBJECTIVE: Computer-assisted surgery (CAS) can improve the accuracy of screw placement and decrease radiation exposure, yet this is not widely accepted among spine surgeons worldwide. The current viewpoint of the spine surgeon on navigation in their everyday practice is an important issue that has not been studied. A survey-based study assessed opinions on CAS to describe the current global attitudes of surgeons on the use of navigation in spine surgery. METHODS: A 12-item questionnaire focusing on the number and type of surgical cases, the type of equipment available, and general opinions toward CAS was distributed to 3348 AOSpine surgeons (a specialty group within the AO [Arbeitsgemeinschaft für Osteosynthesefragen] Foundation). Latent class analysis was used to investigate the existence of specific groups based on the respondent opinion profiles. RESULTS: A response rate of 20% was recorded. Despite a widespread distribution of navigation systems in North America and Europe, only 11% of surgeons use it routinely. High-volume procedure surgeons, neurological surgeons, and surgeons with a busy minimal invasive surgery practice are more likely to use CAS. "Routine users" consider the accuracy, potential of facilitating complex surgery, and reduction in radiation exposure as the main advantages. The lack of equipment, inadequate training, and high costs are the main reasons that "nonusers" do not use CAS. CONCLUSIONS: Spine surgeons acknowledge the value of CAS, yet current systems do not meet their expectations in terms of ease of use and integration into the surgical work flow. To increase its use, CAS has to become more cost efficient and scientific data are needed to clarify its potential benefits.
    World Neurosurgery 03/2012; · 1.77 Impact Factor

Publication Stats

483 Citations
140.10 Total Impact Points


  • 2011–2013
    • Cornell University
      • Department of Biomedical Engineering
      Ithaca, NY, United States
    • Muhimbili Orthopaedic Institute (MOI)
      Dār es Salām, Dar es Salaam, Tanzania
  • 2006–2013
    • Weill Cornell Medical College
      • • Department of Neurological Surgery
      • • Weill Cornell Breast Center
      New York City, New York, United States
  • 2011–2012
    • University Center Rochester
      • Department of Neurosurgery
      Rochester, Minnesota, United States
  • 2007–2012
    • New York Presbyterian Hospital
      • Department of Neurological Surgery
      New York City, New York, United States
  • 2010
    • Technische Universität München
      München, Bavaria, Germany
    • Ludwig-Maximilian-University of Munich
      • Interdisciplinary Centre for Palliative Medicine
      München, Bavaria, Germany
  • 2006–2010
    • Barrow Neurological Institute
      • Department of Neurosurgery
      Phoenix, AZ, United States
  • 2009
    • Karolinska Institutet
      • Institutionen för klinisk neurovetenskap
      Solna, Stockholm, Sweden