bluuebunny/crossref_metadata_2025 huggingface dataset:
Titanium mesh cages for cervical spine stabilization after corpectomy: a clinical and radiological study
Authors: Narotam Pradeep K. , Pauley Sarah M. , McGinn Gregory J.
Published: May 2009

Object. Reconstruction after anterior cervical decompression has involved the use of tricortical iliac crest bone or fibular strut grafts, but has been associated with significant morbidity. In this study the authors evaluated the efficacy of titanium mesh cages (TMCs) for stability and fusion following anterior cervical corpectomy.

Methods. Thirty-seven patients were prospectively evaluated during a 4-year period. The majority presented with spinal cord compression (97%) often due to cervical spondylosis (87%). The TMC was filled with iliac crest bone chips or Surgibone and stabilized by anterior cervical plates (ACPs). The changes in settling ratio, coronal and sagittal angles, and sagittal displacement were determined at 3, 6, and 12 months; immediate postoperative radiographs were used as baseline. Flexion—extension radiographs and computerized tomography (CT) scans (obtained at 1 year) were examined to assess stability, fusion, and bone growth within the TMC.

Complications such as settling, telescoping, migration, and pseudarthrosis were not observed. Dynamic radiography revealed spinal stability in all patients. Cage-related complications occurred in 2.7% (TMC malplacement [one patient]), surgery-related complications in 10.8%, and graft-related complications in 21.6%. Evidence of bone growth into the TMC was documented in 16 (95%) of 17 patients on CT scans. The mean cage height—related settling rates were 4.46% at 3 months (31 patients [p = 0.066]), 3.89% at 6 months (28 patients [p = 0.028]), and 4.35% at 1 year (27 patients [p = 0.958]). The mean sagittal displacement changed by 3.9% (23 patients [p = 0.73]). The mean coronal and sagittal angles changed 2.89° (30 patients [p = 0.498]) and 2.09° (29 patients [p = 0.001]) at 1 year, respectively, or at last follow up from baseline. No significant differences in the radiological indices were seen when multilevel vertebrectomy cases were compared with single-level vertebrectomy (p = 0.221), smoking status, or age.

Conclusions. Titanium mesh cages, in combination with ACPs, are safe and effective for vertebral replacement in the cervical spine.
Differential temporal expression of matrix metalloproteinases after spinal cord injury: relationship to revascularization and wound healing
Authors: Goussev Staci , Hsu Jung-Yu C. , Lin Yong , Tjoa Tjoson , Maida Nino , Werb Zena , Noble-Haeusslein Linda J.
Published: May 2009

Object. Matrix metalloproteinases (MMPs), particularly MMP-9/gelatinase B, promote early inflammation and barrier disruption after spinal cord injury (SCI). Early blockade of MMPs after injury provides neuroprotection and improves motor outcome. There is recent evidence, however, that MMP-9 and MMP-2/gelatinase A participate in later wound healing in the injured cord. The authors therefore examined the activity of these gelatinases during revascularization and glial scar formation in the contused murine spinal cord.

Methods. Gelatinase activity was evaluated using gelatin zymography 24 hours after a mild, moderate, or severe contusion injury. The active form of MMP-2 was not detected, whereas MMP-9 activity was evident in all SCI groups and rose with increasing injury severity. The temporal expression of gelatinases was then examined using gelatin zymography after a moderate SCI. The active form of MMP-9 was most prominent at 1 day, extended through the early period of revascularization, and returned to control by 14 days. The active form of MMP-2 appeared at 7 days postinjury and remained elevated compared with that documented in sham-treated mice for at least 21 days. Increased MMP-2 activity coincided with both revascularization and glial scar formation. Using in situ zymography, gelatinolytic activity was detected in the meninges, vascular elements, glia, and macrophage-like cells in the injured cord. Results of immunolabeling confirmed the presence of gelatinase in vessels during revascularization and in reactive astrocytes associated with glial scar formation.

Conclusions. These findings suggest that although MMP-9 and -2 exhibit overlapping expression during revascularization, the former is associated with acute injury responses and the latter with formation of a glial scar.
The role of multiple hyperbaric oxygenation in expanding therapeutic windows after acute spinal cord injury in rats
Authors: Huang Lixin , Mehta Maheshkumar P. , Nanda Anil , Zhang John H.
Published: May 2009

Object. Hyperbaric oxygenation (HBO) therapy has been reported to improve neurological recovery after spinal cord injury (SCI). In the present study, the authors examined whether multiple HBO therapy can expand the therapeutic window after acute SCI.

Methods. Seventy rats were randomly assigned to seven groups: sham surgery; SCI without treatment; single HBO treatment beginning at 30 minutes, 3 hours, and 6 hours after SCI; and multiple HBO treatments starting at 6 and 24 hours postinjury. Mild SCI was induced by adjusting the height of a weight drop (10 g) to 6.25 mm above the exposed spinal cord. A single HBO administration was performed at 2.82 ata for 1 hour. The multiple HBO treatment modality was performed once daily for 1 week. All rats underwent behavioral testing with the Basso-Beattie-Breshnahan locomotor rating scale twice a week. Rats were killed on Day 42 postinjury and specimens comprising the lesioned area were histopathologically examined. Those rats that received single HBO intervention beginning at 30 minutes and 3 hours and those that received multiple HBO treatment starting at 6 hours following injury made significantly greater neurological recoveries than those in the nontreatment SCI group. These rats also retained more sparing tissue than controls.

Conclusions. The results of this study demonstrate that multiple HBO treatments can expand the therapeutic window for acute SCI to 6 hours after injury.
Tethering of the spinal cord in mouse fetuses and neonates with spina bifida
Authors: Stiefel Dorothea , Shibata Takashi , Meuli Martin , Duffy Patrick G. , Copp Andrew J.
Published: May 2009

Object. Tethering of the spinal cord is a well-known complication in humans with spina bifida aperta or occulta. Its pathogenesis consists of a pathological fixation of the spinal cord resulting in traction on the neural tissue which, in turn, leads to ischemia and progressive neurological deterioration. Although well established in humans, this phenomenon has not been described in animal models of spina bifida.

Methods. A fetal mouse model with naturally occurring, genetically determined spina bifida was produced by generating double mutants between the curly tail and loop-tail mutant strains. Microdissection, labeling with 1,1′-dioctadecyl-3,3,3,′,3′-tetramethylindocarbocyanine perchlorate, immunohistochemistry for neurofilaments, H & E staining of histological sections, and whole-mount skeletal preparations were performed and comparisons made among mutant and normal fetuses.

Normal fetuses exhibited the onset of progressive physiological ascent of the spinal cord from embryonic Day 15.5. Spinal cord ascent resulted, by embryonic Day 18.5, in spinal nerve roots that pass caudolaterally from the spinal cord toward the periphery. In contrast, fetuses with spina bifida exhibited spinal cord tethering that resulted, at embryonic Day 18.5, in nerve roots that run in a craniolateral direction from the spinal cord. The region of closed spinal cord immediately cranial to the spina bifida lesion exhibited marked narrowing, late in gestation, suggesting that a potentially damaging stretch force is applied to the spinal cord by the tethered spina bifida lesion.

Conclusions. This mouse model provides an opportunity to study the onset and early sequelae of spinal cord tethering in spina bifida.
Biomechanical comparison of facet-sparing laminectomy and Christmas tree laminectomy
Authors: Detwiler Paul W. , Spetzler Christina B. , Taylor Sara B. , Crawford Neil R. , Porter Randall W. , Sonntag Volker K. H.
Published: May 2009

Object. The authors compared differences in biomechanical stability between two decompressive laminectomy techniques for treating lumbar stenosis. A Christmas tree laminectomy (CTL), in which bilateral facetectomies and foraminotomies are performed, was compared with facet-sparing laminectomy (FSL), in which the facets are undercut but not resected. Spinal instability was assessed immediately postoperatively and again after discectomy to model long-term degeneration.

Methods. Sixteen motion segments obtained from five human cadaveric lumbar specimens were studied in vitro by conducting nondestructive flexibility tests. Specimens were tested intact, after FSL or CTL, and again after discectomy. Nonconstraining torques (≤ 5 Nm) were applied to induce flexion, extension, axial rotation, and lateral bending; strings and pulleys were used while vertebral angles were measured. Anteroposterior translation in response to shear loading (≤ 100 N) was also measured. Angular motion, shear motion, and sagittal-plane axes of rotation were compared to evaluate stability.

Compared with the intact condition, CTL-treated specimens had significantly larger increases in angular motion during flexion, lateral bending, and axial rotation than their FSL-treated counterparts (p < 0.05, nonpaired Student t-tests). Subsequent discectomy caused greater increases in motion in the CTL group. Axes of rotation shifted less from their normal positions after FSL than after CTL.

Conclusions. This study provides objective evidence that the treatment of lumbar stenosis with FSL induces less biomechanical instability and alters kinematics less than FSL. These findings support the use of the FSL in treating lumbar stenosis.
Closed posterior superior iliac spine impeding pediculocorporeal S-1 screw insertion
Authors: Kaptanoglu Erkan , Okutan Ozerk , Tekdemir Ibrahim , Beskonakli Etem , Deda Haluk
Published: May 2009

Object. Placement of pedicle screws into S-1 is difficult. In cases in which there is a closed posterior superior iliac spine (PSIS), its medial situation prevents lateral oblique placement of the screw inserter sleeve and directing the screw to the anteromedial aspect of S-1. In the present study, the authors discuss anatomical variations of the PSIS and sacrum, and they describe a safe and effective S-1 screw insertion technique.

Methods. The relation of 50 PSISs obtained from 25 dry pelvises (15 male and 10 female cadavers) was examined. The distance from the inferolateral aspect of the S-1 superior articular facet to its promontory was estimated. The relation between the point of anterior penetration of the “screw line” and “safe zone” was analyzed. Penetration of screw lines into the S-1 body was also measured. (An illustrative case of closed PSIS is presented with pre- and postoperative computerized tomography [CT] scan findings.)

The authors found that that PSIS was situated in 28% of the specimens. When screws were directed anteromedially, the screw lines failed to penetrate the S-1 body in 24% of the male and in 15% of female specimens. The screw lines deviated from the safe zone anteriorly in 34% of the male and in 20% of the female specimens. When the PSIS was medial to the line that connects the inferolateral aspect of the S-1 superior articular facet to the promontory, a classification of closed PSIS was assigned.

Conclusions. The accuracy of the placement of the screws and their pullout strength are increased when using the present technique. Preoperative CT scanning should be performed to determine the presence of a closed PSIS; in cases in which a closed PSIS is found, the ilium should be resected to enable a greater anteromedial trajectory for placement of S-1 pedicle screws.
Factors related to long-term outcome after decompressive surgery for ossification of the ligamentum flavum of the thoracic spine
Authors: Miyakoshi Naohisa , Shimada Yoichi , Suzuki Tetsuya , Hongo Michio , Kasukawa Yuji , Okada Kyoji , Itoi Eiji
Published: May 2009

Object. Factors related to long-term surgical outcome of thoracic myelopathy caused by ossification of the ligamentum flavum (OLF) have not been fully investigated. To evaluate these factors, the authors reviewed medical records obtained in patients who had undergone decompressive surgery for thoracic OLF.

Methods. Thirty-four patients in whom decompressive surgery was performed for thoracic OLF (mean follow-up period 8 years) were recruited. Fourteen patients underwent simultaneous decompressive surgery for cervical or lumbar lesions. Patient age, duration of symptoms, OLF type, dural adhesion, neurological status classified by the Japanese Orthopaedic Association (JOA) scale before and after surgery (1 month postoperatively and at final follow up), and recovery rate were reviewed. The ossified ligamentum flavum was classified into five types according to Sato's classification by assessing preoperative computerized tomography scans. The mean preoperative JOA score (5) was significantly improved at 1 month after surgery (7.1) and at final follow up (7.9) (p < 0.05). Recovery rates at 1 month and at final follow up were 34.6 and 44.2%, respectively. No significant correlations were found between age, OLF type, and neurological status before and after surgery. In patients with dural adhesion, which was observed in cases of larger-type OLF (p < 0.02), lower JOA scores were observed compared with those in patients without dural adhesion both preoperatively and at 1 month after surgery (p < 0.05) but not at the final follow-up examination. Higher JOA scores and recovery rates were demonstrated in patients who had undergone simultaneous surgery than in those who had not undergone simultaneous surgery at 1 month (p < 0.05) but not at the final follow up. Using multiple regression analysis, the authors identified the duration of preoperative symptoms as the most important predictor of a high JOA score and recovery rate at the final follow up.

Conclusions. Duration of preoperative symptoms represents the most important predictor of long-term surgeryrelated outcome in patients treated for thoracic OLF. The type of ossified ligamentum flavum, dural adhesion, and simultaneous surgery for coexistent cervical or lumbar lesions do not appear to influence the long-term postoperative prognosis.
Spinal blood flow in 24-hour megadose glucocorticoid treatment in awake pigs
Authors: Drescher Wolf R. , Weigert Karen P. , Bünger Mathias H. , Hansen Ebbe S. , Bünger Cody E.
Published: May 2009

Object. Because of the controversy regarding the benefits of 24-hour administration of methylprednisolone in patients with spinal cord injury (SCI), it is important to investigate its mechanism of action and side effects. This study was conducted to determine if high-dose methylprednisolone modulates neural and vertebral blood flow in an awake large-sized animal model without SCI.

Methods. From a group of 18 immature female domestic pigs born to nine different litters, nine animals were randomly allocated to receive methylprednisolone treatment, whereas their nine female siblings served as controls. Drug or placebo was applied in a blinded fashion by a third person not involved in the study.

The following treatment for SCI, as suggested by the North American Spinal Cord Injury Study, was administered to the awake pig: methylprednisolone (30 mg/kg of body weight) was infused into the jugular vein during a 15-minute period, followed by a 45-minute pause, and the infusion was maintained over a 23-hour period at a dose of 5.4 mg/kg body weight/hour. By means of the radioactive tracer microsphere technique, spinal cord blood flow (SCBF) was measured in the awake standing pig in the cerebrum, and in spinal gray and white matter, nerve roots, endplates, cancellous bone, cortical shell, and T12—L2 discs. Blood flow was measured before, 1 hour after initiation of infusion, and 24 hours postinfusion.

Examination of blood flow in the neural and vertebral tissue samples, as well as of central hemodynamics, revealed no significant difference between the experimental and control groups, and this parity was maintained throughout the experimental phases.

Conclusions. In the awake pig model, 24-hour methylprednisolone treatment does not modulate cerebral or SCBF, nor does it increase the risk for vertebral osteonecrosis by producing vertebral ischemia.
Inhibition of proteoglycan and type II collagen synthesis of disc nucleus cells by nicotine
Authors: Kim Keun Su , Yoon S. Tim , Park Jin Soo , Li Jun , Park Moon Soo , Hutton William C.
Published: May 2009

Object. Systemic nicotine has been hypothesized to cause degeneration of the intervertebral disc which in turn decreases vascular supply to the disc through a cholinergic receptor—mediated process. Another possible mechanism may be through direct regulatory effects on disc cells. In this study, the authors tested the hypothesis that nicotine adversely affects nucleus pulposus cells by directly inhibiting proteoglycan synthesis and gene expression of type II collagen (Phase I study). They also assessed the hypothesis that nicotine inhibits the bone morphogenetic protein (BMP)—2-induced upregulation of extracellular matrix (Phase II study).

Methods. Cells were isolated from nucleus pulposus obtained in rat lumbar discs and cultured on a monolayer. Media were treated with nicotine and/or recombinant human (rh)BMP-2 for 7 days. Sulfated glycosaminoglycan (SO4-GAG) in media was quantified using 1,9-dimethylmethylene blue (DMMB) assay. Gene assay of types I and II collagen, Sox9, and glyceraldehyde-3-phosphate dehydrogenase were quantified using reverse transcriptase—polymerase chain reaction (RT-PCR) and real time PCR. In the Phase I study, nicotine-treated (100 µg/ml) and nontreated cells were compared. The s-GAG production and messenger RNA (mRNA) of type II collagen and Sox9 decreased significantly in the nicotine-treated group. In the Phase II study, five groups were compared: 1) nontreatment; 2) rhBMP-2 only (100 ng/ml); and 3–5) with rhBMP-2 (100 ng/ml) and increasing doses of nicotine (1 [third group], 10, [fourth group], 100 [fifth group] µg/ml). The SO4-GAG production and mRNA of type II collagen and Sox9 decreased significantly in the groups treated with rhBMP-2 combined with 10 and 100 µg/ml of nicotine compared with the group treated with rhBMP-2.

Conclusions. The results of this study raise the possibility that nicotine may contribute to the process of disc degeneration by a direct effect on the nucleus pulposus cells, possibly by antagonizing the effect of BMP-2.
Magnetic resonance imaging—guided percutaneous fenestration of a cervical intradural cyst
Authors: Takahashi Shinobu , Morikawa Shigehiro , Egawa Masaaki , Saruhashi Yasuo , Matsusue Yoshitaka
Published: May 2009

✓ The authors describe the case of a high cervical, intradural extramedullary cyst located anterior to the spinal cord in a 13-year-old boy. The lesion was fenestrated percutaneously by using real-time magnetic resonance (MR) imaging guidance and a local anesthetic agent. The patient's symptom, severe exercise-induced headache, immediately resolved after treatment. Nine months later, complete disappearance of the cyst was confirmed on MR imaging and computerized tomography myelography. Magnetic resonance imageing—guided fenestration can be considered a minimally invasive option for intradural cystic lesions.
Spinal intradural extramedullary cavernous angioma
Authors: Nozaki Kazuhiko , Inomoto Takaaki , Takagi Yasushi , Hashimoto Nobuo
Published: May 2009

✓ The spinal intradural extramedullary cavernous angioma is a rare clinical entity. Only 20 surgically treated cases have been reported. The authors report on an additional case in which the lesion was located in the cervical region, and they summarize its unique clinical features. Intradural extramedullary cavernous angiomas occur predominantly in males, in the lower thoracolumbar region, exhibit a relatively high association with subarachnoid hemorrhage, and mostly adhere to the nerve root or spinal cord. Because resection is possible without causing morbidity and because outcome depends on the severity of preoperative neurological dysfunction, precise diagnosis and timely treatment are mandatory.
Posterolateral percutaneous endoscopic lumbar foraminotomy for L5—S1 foraminal or lateral exit zone stenosis
Authors: Ahn Yong , Lee Sang-Ho , Park Woo-Min , Lee Ho-Yeon
Published: May 2009

✓ The purpose of this study was to determine the efficacy and feasibility of posterolateral percutaneous endoscopic lumbar foraminotomy (PELF) for foraminal or lateral exit zone stenosis of the L5—S1 level in the awake patient.

Twelve consecutive patients with L5—S1 foraminal stenosis and associated leg pain underwent PELF between May 2001 and July 2002. Under fluoroscopic guidance, posterolateral endoscopic foraminal decompression was performed using a bone reamer, endoscopic forceps, and a laser. Using this new technique, the authors removed part of the hypertrophied superior facet, thickened ligamentum flavum, and protruded disc compressing the exiting (L-5) nerve root. Clinical outcome was measured using the Macnab criteria. The mean follow-up period was 12.9 months. All the patients were discharged within 24 hours. Satisfactory (excellent or good) results were demonstrated in 10 patients. There was no complication.

The PELF procedure provides a simple alternative for treating lumbar foraminal or lateral exit zone stenosis in selected cases. The authors found that the posterolateral endoscopic approach to the L5—S1 foramen was usually possible and that using a bone reamer to undercut the superior facet was effective.
Selection of instrumentation and fusion levels for scoliosis: where to start and where to stop
Authors: Bridwell Keith H.
Published: May 2009

Object.Although there are several papers in the literature regarding selection of fusion levels in the adolescent patient, fewer articles pertain to this in the adult patient. The author reviewed his experience and the literature and reports on the choice of fusion levels in the adolescent and adult patient.

Methods.After a review of available data, the author determined that the proximal and distal extent of the fusion should be based on defining curves as either major or minor in the adolescent patient. It is often possible to exclude minor curves from the fusion. Relative Cobb measurement, apical deviation from the plumb line, and apical rotation are the most useful means of distinguishing a major from a minor curve. Otherwise, the proximal and distal extent of a fusion should be performed in such a way that the proximal and distal vertebrae are both neutral and stable (bisected by the center sacral line) postoperatively. Additional segments may need to be included in the adult patient in whom extensive degenerative changes and subluxations are present. The decision of whether to terminate a long fusion at L-5 or the sacrum in an adult degenerative lumbar curve is complex and many factors have to be considered.

Conclusions.Guidelines exist for fusion levels in both adolescent and adult patients. Not all curves require fusion. There are many coronal and sagittal considerations that have to be analyzed when making the final decision.
Evaluation and treatment of adult spinal deformity
Authors: Heary Robert F.
Published: May 2009

✓ Spinal deformity is a complex and dynamic process that occurs in both the sagittal and coronal planes of the thoracolumbar spine. Successful treatment is aimed at achieving satisfactory balance in both of these planes. The spinal curvatures in the adult differ greatly from those in adolescents. As a general rule the adult curves tend to be stiffer, whereas adolescent curves are more flexible. In addition to cosmetic concerns, adult patients frequently present with pain and neurological symptoms in contrast to adolescents who usually do not experience this degree of pain or neurological symptoms. The treatment of adult spinal deformity differs substantially from that of adolescent deformity. Surgeries in the former tend to be more complex procedures associated with higher rates of intra- and perioperative complications. The goals of surgery in the adult are to obtain a solid fusion with a balanced spine, to relieve pain, and to prevent further deformity. A secondary goal is to correct the curve, and, in so doing, to improve the cosmetic appearance. In this review the author addresses the basic principles of spinal corrective surgery in the adult and provides insight into the varied treatment options available.
Contribution of recombinant human bone morphogenetic protein—2 to the rapid creation of interbody fusion when used in transforaminal lumbar interbody fusion: a preliminary report
Authors: Mummaneni Praveen V. , Pan Jeff , Haid Regis W. , Rodts Gerald E.
Published: May 2009

Object. The authors compared fusion rates in transforaminal lumbar interbody fusion (TLIFs) when using either autograft or bone morphogenetic protein (BMP) placed in the interbody space.

Methods. Between September 2002 and December 2003, the authors performed 44 TLIF operations. Follow-up data were available for 40 patients. Of the 40 procedures, 19 involved cages filled with iliac crest autograft (Group 1) and 21 involved cages filled with a medium kit of recombinant human (rh) BMP-2 (Group 2). In all Group 2 patients, one BMP sponge was placed anterior to the cage and another was placed within the cage. In 12 of the Group 2 patients, iliac crest autograft was placed posterior to the BMP-filled cage (Group 2A). In the remaining nine Group 2 patients, only local autograft was placed posterior to the BMP-filled cage (Group 2B). Assessment of fusion was performed using dynamic radiography at 3-month intervals. Outcomes were assessed using the Prolo Scale, and iliac crest donor site pain was measured using a Visual Analog Scale (VAS).

The mean follow-up period was 9 months (range 3–18 months). In Group 1 patients, one pseudarthrosis was detected. In Group 2 patients, dynamic radiography demonstrated solid fusion in all patients except one in Group 2B. Fiftyeight percent of patients in whom iliac crest autograft was used complained of donor site pain 6 months after surgery (5 of 10 points on the VAS). Symptomatic foraminal bone formation was not observed in any Group 2 patient.

Conclusions. The use of rhBMP-2 is safe in TLIFs when the sponges are placed away from the dura mater, and BMP promotes a more rapid fusion than iliac crest autograft alone. The use of rhBMP-2 in combination with local autograft is an excellent option for promoting solid fusion with TLIF, and it eliminates the possibility of iliac donor site pain.
Thoracic microendoscopic discectomy
Authors: Perez-Cruet Mick J. , Kim Bong-Soo , Sandhu Faheem , Samartzis Dino , Fessler Richard G.
Published: May 2009

Object.Various approaches exist for the treatment of thoracic disc herniation. Anterior approaches facilitate ventral exposure but place the intrathoracic contents at risk. Posterolateral approaches require extensive muscle dissection that adds to the risk of postoperative morbidity. The authors have developed a novel posterolateral, minimally invasive thoracic microendoscopic discectomy (TMED) technique that provides an approach to the thoracic spine which is associated with less morbidity.

Methods.Seven patients 23 to 54 years old with nine disc herniations underwent TMED. All lesions were soft lateral or midline thoracic disc herniations. Under fluoroscopic guidance with the patient positioned prone, the authors used a muscle dilation approach and the procedure was performed with endoscopic visualization through a tubular retractor.

Based on a modified Prolo Scale, five patients experienced excellent results, one good, and one fair. No case required conversion to an open procedure. The mean operative time was 1.7 hours per level, and estimated blood loss was 111 ml per level. Hospital stays were short, and no complications occurred.

Conclusions.The TMED is safe, effective, and provides a minimally invasive posterolateral alternative for treatment of thoracic disc herniation without the morbidity associated with traditional approaches.
Metabolic neuroimaging of the cervical spinal cord in patients with compressive myelopathy: a high-resolution positron emission tomography study
Authors: Uchida Kenzo , Kobayashi Shigeru , Yayama Takafumi , Kokubo Yasuo , Nakajima Hideaki , Kakuyama Michiko , Sadato Norihiro , Tsuchida Tatsuro , Yonekura Yoshiharu , Baba Hisatoshi
Published: May 2009

Object. The authors conducted a study to examine whether high-resolution [18F]fluorodeoxyglucose (FDG)—positron emission tomography (PET) could be used to visualize deterioration of cervical spinal cord function associated with various degrees of compression and to determine its potential usefulness during assessment of compressive myelopathy.

Methods. In 23 patients requiring decompressive surgery for myelopathy FDG-PET was performed. The preoperative findings of high-resolution FDG-PET were compared with the neurological scores and magnetic resonance (MR) imaging findings. The preoperative standardized uptake value (SUV) of FDG utilization rate of the cervical cord correlated with the pre- (r = 0.497, p = 0.016) and postoperative neurological scores (r = 0.595, p = 0.003), as well as with the rate of neurological improvement postoperatively (r = 0.538, p = 0.008). The FDG utilization rate did not correlate with the high signal intensity on T2-weighted MR images.

Conclusions. Analysis of these results indicates that high-resolution FDG-PET imaging provides useful qualitative and quantitative estimates of impaired metabolic activity of the compromised cervical cord that correlate closely with the severity of neurological dysfunction.
Vulnerability of the subcostal nerve to injury during bone graft harvesting from the iliac crest
Authors: Chou Dean , Storm Phillip B. , Campbell James N.
Published: May 2009

Object. Autologous bone graft harvesting from the iliac crest remains the gold standard for fusion surgery. One disadvantage of autologous bone harvesting is the patient's enduring postoperative pain at the donor site. Nerve injury is one of the postulated mechanisms that may account for this pain. The object of this study was to determine whether the lateral cutaneous branch of the subcostal nerve is vulnerable to injury in the process of obtaining grafts from the anterior iliac crest.

Methods. Anatomical dissections were performed on 10 cadaveric specimens to ascertain the size of the T-12 subcostal nerve and its position in relation to the iliac crest.

Conclusions. The lateral cutaneous branch of the subcostal nerve may lie as close as 6 cm from the anterior superior iliac spine. This nerve is very vulnerable to injury when harvesting bone from the anterior iliac crest. Knowledge of the anatomy may decrease the risk of injury to this nerve.
The use of bone morphogenetic protein—6 gene therapy for percutaneous spinal fusion in rabbits
Authors: Laurent Jeffrey J. , Webb K. Michael , Beres Elisa J. , McGee Kevin , Li Jinzhong , van Rietbergen Bert , Helm Gregory A.
Published: May 2009

Object.Fusion procedures in the lumbar spine have been performed in the US since 1911. Since that time, the indications and techniques for spinal fusion have evolved. Despite technical advancements, spinal fusion remains a major operation, and fusion nonunion rates of up to 35% are still reported. In this study, the authors were able to induce intertransverse process fusions in immune-competent New Zealand White rabbits by percutaneous administration of an adenoviral vector containing the bone morphogenetic protein(BMP-6)gene (Ad-BMP-6). The results represent an important step forward in finding new methods to increase the success and decrease the morbidity associated with spinal fusion.

Methods.Five New Zealand White rabbits were used. Injection of the adenoviral construct was performed at multiple levels (bilaterally) in each animal while using fluoroscopic guidance. Injection consisted of either Ad-BMP-6 or Ad—β-galactosidase (β-gal) (control). Because multiple levels were injected, each animal served as an internal control. The animals underwent postinjection computerized tomography (CT) scanning at 7 and 14 weeks. After undergoing final CT scanning, the animals were killed and the spines were harvested. The fusion sites were analyzed by gross inspection, histopathological methods, and micro—CT studies.

Conclusions.The results of this study show that an anatomically precise fusion can be accomplished by percutaneous administration of gene therapy. The next step in these studies will be extension of the technique to nonhuman primates and eventually to human clinical studies.
Single-unit artificial intervertebral disc
Authors: Alberts Russell , Patil Arun-Angelo , Zhou Dongxue
Published: May 2009

Object. The authors describe a new type of artificial disc called a single-unit artificial disc (SUAD). It is a single-unit disc without components, and there is no fixation system with which to maintain it in the disc space. It is theorized that its shape, hardness, and surface consistency, together with the compressive force exerted by the body's axial load, should be adequate to maintain the position of the disc in the disc space. In this paper the authors present their results of the kinematic tests in which the stability and integrity of the SUADs was tested.

Methods. Panorobot was used for kinematic test fixture for fatigue testing for different types of SUAD. The test was performed after placing the disc between the C-5 and C-6 vertebral bodies (VBs) obtained from a cadaver. Eight pounds of weight was placed on the top of the container housing the C-5 VB to account for the weight of the head. The robot performed the following movements: 1) flexion—extension, 4.7° each; 2) lateral left—right bending, ± 2.1°; and 3) coupled rotation, ± 3.8°. Two flat discs (FDs) of 85 durometer (D), four 30D FD, two recess-edged discs (REDs) of 85D, and four custom-designed discs (CDDs) (custom molded to the disc space) of 30D were tested.

None of the discs showed cracks or breakage at the end of the study. After 1 million cycles of excursions all 85D and 30D FD, and both 85D REDs showed weight loss. The 30D CDDs showed minimal weight gain at 1 million cycles. One of the CDDs, tested up to 5 million cycles, did lose weight at 5 million cycles.

One 85D FD was extruded after 0.2 million cycles and one 85D RED rotated within the disc space. All other discs maintained their position in the disc space. Dimensional changes were minimal. Scanning electron microscopy of particles collected from one 30D CDD sample after 1 million cycles showed rough irregular granular particles 1 to 600 µm in diameter.

Conclusions. These findings show that a 30D SUAD can maintain its position in the disc space without any anchoring device. Furthermore, at 1 million cycles of testing of 30 D SUAD, FDs did as well as the CDDs. This may be because softer discs mold to changes in dimension of the disc space. In addition the softer discs tend to wear less than the harder ones. Further fatigue study of 10 million cycles is needed to determine long-term efficacy, and the effects of wear on particles surrounding the joints need to be studied.
Biomechanical testing of anterior and posterior thoracolumbar instrumentation in the cadaveric spine
Authors: Eichholz Kurt M. , Hitchon Patrick W. , From Aaron , Rubenbauer Paige , Nakamura Satoshi , Lim Tae Hong , Torner James
Published: May 2009

Object. Thoracolumbar burst fractures frequently require surgical intervention. Although the use of either anterior or posterior instrumentation has advantages and disadvantages, there have been few studies in which these two approaches have been compared biomechanically.

Methods. Ten human cadaveric spines were subjected to subtotal L-3 corpectomy. In five spines placement of L-3 wooden strut grafts with lateral L2–4 dual rod and screw instrumentation was performed. Five other spines underwent L1–5 pedicle screw fixation. The spines were fatigued between steps of the experiment. The spines were load tested with pure moments of 1.5, 3, 4.5, and 6 Nm in the intact state and after placement of instrumentation in six degrees of freedom (flexion, extension, right and left lateral bending, and right and left axial rotation).

In axial rotation posterior instrumentation significantly increased spinal rigidity compared with that of the intact state, whereas anterior instrumentation did not. Combined anterior—posterior instrumentation did not significantly increase the rigidity of the spine when compared with anterior or posterior instrumentation alone. Posterior instrumentation alone provided a greater reduction in angular rotation compared with anterior instrumentation alone in all degrees of freedom; however, statistical significance was achieved only in extension at 6 Nm.

Conclusions. The increased rigidity provided by pedicle screw instrumentation compared with the intact state or with anterior instrumentation is due to the longer construct spanning five levels and the three-column engagement of the pedicle screws. The decision to use anterior or posterior instrumentation should be based on the clinical necessity of canal decompression and correction of angulation.
Mechanical properties and function of the spinal pia mater
Authors: Ozawa Hiroshi , Matsumoto Takeo , Ohashi Toshiro , Sato Masaaki , Kokubun Shoichi
Published: May 2009

Object. The pia mater has received little attention regarding its function in the deformation of the spinal cord under compression. In this study the mechanical properties and function of the spinal pia mater were investigated using three methods.

Methods. Spinal cord segments were excised from rabbits. The elastic modulus of the pia mater was measured by performing a tensile test using specimens with the pia mater intact and ones with the pia mater stripped off. The stiffness of the spinal cord was examined by performing a compression test with specimens containing an intact pia mater and ones with a pia mater that was incised at both sides. The cross-sectional area and circumference of the spinal cord were measured on axial views of magnetic resonance images in patients with cervical disc herniations before and after surgery.

The pia mater had an elastic modulus of 2300 kPa, which was 460 times higher than that of spinal cord parenchyma. By covering the parenchyma, it tripled the overall elastic modulus of the spinal cord. The pia mater increased the stiffness of the spinal cord and enhanced its shape recovery after removal of the compression. The cross-sectional area of the spinal cord increased after surgery, whereas the circumference of the spinal cord changed little.

Conclusions. The pia mater firmly covers the spinal cord and has a high elastic modulus; it therefore provides a constraint on the spinal cord surface. It prevents elongation of the circumference and produces a large strain energy that is responsible for shape restoration following decompression.
Anterior atlas fracture following suboccipital decompression for Chiari I malformation
Authors: O'Shaughnessy Brian A. , Salehi Sean A. , Ali Saad , Liu John C.
Published: May 2009

✓ Chiari I malformation, a congenital disorder involving downward displacement of the cerebellar tonsils through the foramen magnum, is often treated surgically by performing suboccipital craniectomy and C-1 laminectomy. The authors report two cases in which fracture of the anterior atlantal arch occurred during the postoperative period following Chiari I decompression and C-1 laminectomy causing significant neck pain. The findings indicate that interruption of the integrity of the posterior arch of C-1, iatrogenically or otherwise, confers increased risk of anterior arch fracture. A C-1 fracture should therefore be considered in the differential diagnosis of posterior cervical pain in patients who have previously undergone decompression for Chiari I malformation.
Neurological complications of lumbar artificial disc replacement and comparison of clinical results with those related to lumbar arthrodesis in the literature: results of a multicenter, prospective, randomized investigational device exemption study of Charité intervertebral disc
Authors: Geisler Fred H. , Blumenthal Scott L. , Guyer Richard D. , McAfee Paul C. , Regan John J. , Johnson J. Patrick , Mullin Bradford
Published: May 2009

Object. Arthrodesis is the gold standard for surgical treatment of lumbar degenerative disc disease (DDD). Solid fusion, however, can cause stress and increased motion in the segments adjacent to the fused level. This may initiate and/or accelerate the adjacent-segment disease process. Artificial discs are designed to restore and maintain normal motion of the lumbar intervertebral segment. Restoring and maintaining normal motion of the segment reduces stresses and loads on adjacent level segments. A US Food and Drug Administration Investigational Device Exemptions multicentered study of the Charité artificial disc was completed. The control group consisted of individuals who underwent anterior lumbar interbody fusion involving BAK cages and iliac crest bone graft. This is the first report of Class I data in which a lumbar artificial disc is compared with lumbar fusion.

Methods. Of 304 individuals enrolled in the study, 205 were randomized to the Charité disc-treated group and 99 to the BAK fusion—treated (control) group. Neurological status was equivalent between the two groups at 6, 12, and 24 months postoperatively. The number of patients with major, minor, or other neurological complications was equivalent. There was a greater incidence of both major and minor complications in the BAK fusion group at 0 to 42 days postoperatively. Compared with data reported in the lumbar fusion literature, the Charité disc—treated patients had equivalent or better mean changes in visual analog scale and Oswestry Disability Index scores.

Conclusions. The Charité artificial disc is safe and effective for the treatment of single-level lumbar DDD, resulting in no higher incidence of neurological complications compared with BAK-assisted fusion and leading to equivalent or better outcomes compared with those obtained in the control group and those reported in the lumbar fusion literature.
Three-level and four-level anterior cervical discectomies and titanium cage—augmented fusion with and without plate fixation
Authors: Hwang Shiuh-Lin , Lin Chih-Lung , Lieu Ann-Shung , Lee Kung-Shing , Kuo Tai-Hung , Hwang Yan-Fen , Su Yu-Feng , Howng Shen-Long
Published: May 2009

Object. Cage-assisted anterior cervical discectomy and fusion (ACDF) has proven to be a safe and effective procedure for the treatment of one- and two-level degenerative disc disease (DDD). To the authors' knowledge, clinical results after three- and four-level interbody cage—augmented ACDF have not been reported in the literature. The authors investigated the safety and effectiveness of titanium cages used in such procedures and evaluated the results in cases with or without plate fixation.

Methods. Fifty-six patients suffering from cervical DDD were divided into two groups. Group 1 included 32 patients who underwent titanium cage—assisted ACDF; Group 2 included 24 patients who underwent the same procedure, supplemented with plate fixation. The cervical DDD was confirmed by radiography and magnetic resonance imaging. The patients underwent radiographic evaluation to assess cervical lordosis, segmental height of cervical spine, the height of the foramina, and spinal stability. Neurological outcomes were assessed using the Japanese Orthopaedic Association (JOA) scores. Neck pain was graded using a 10-point visual analog scale (VAS). The follow-up period ranged from 13 to 28 months (mean 17.2 months).

In both Groups 1 and 2 significant increase (p < 0.001) was demonstrated in the JOA scores (preoperatively 10.7 ± 2.4 and 11.1 ± 2, postoperatively 13.9 ± 2.2 and 14.1 ± 2.3, respectively) and VAS pain scores (preoperatively 8.8 ± 0.9 and 8.5 ± 1, postoperatively 3.1 ± 2.1 and 2.8 ± 1.8, respectively); however, there was no significant intergroup difference. A significant increase in the cervical lordosis, foraminal height, and segmental height was observed in both groups. Good stability of cage fusion was obtained in both groups 12 months postoperatively (90.6% in Group 1 and 91.7% in Group 2); however, there were no statistically significant intergroup differences. The complication rate in Group 2 was higher than that in Group 1. The hospital length of stay in Group 1 was significantly lower than in Group 2 (p < 0.001).

Conclusions. Analysis of these findings demonstrated that titanium cage—assisted ACDF provided long-term stabilization, increased lordosis, increased segmental height, and increased foraminal height. In both groups good neurological outcomes were achieved and donor site morbidity was avoided. The lower complication rate and shorter hospital stay, however, make the cage-assisted fusion without plate fixation better than with plate fixation.
Long-term results of expansive open-door laminoplasty for ossification of the posterior longitudinal ligament of the cervical spine
Authors: Ogawa Yuto , Toyama Yoshiaki , Chiba Kazuhiro , Matsumoto Morio , Nakamura Masaya , Takaishi Hironari , Hirabayashi Hisashi , Hirabayashi Kiyoshi
Published: May 2009

Object. Numerous surgical procedures have been developed for treatment of ossification of the posterior longitudinal ligament (OPLL) of the cervical spine, and these can be performed via three approaches: anterior, posterior, or combined anterior—posterior. The optimal approach in cases involving OPLL-induced cervical myelopathy, however, remains controversial. To address this issue, the authors assessed the benefits and limitations of expansive open-door laminoplasty for OPLL-related myelopathy by evaluating mid- and long-term clinical results.

Methods. Clinical results obtained in 72 patients who underwent expansive open-door laminoplasty between 1983 and 1997 and who were followed for at least 5 years were assessed using the Japanese Orthopaedic Association (JOA) scoring system. The mean preoperative JOA score was 9.2 ± 0.4; at 3 years postoperatively, the JOA score was 14.2 ± 0.3 and the recovery rate (calculated using the Hirabayashi method) was 63.1 ± 4.5%, both having reached their highest level. These favorable results were maintained up to 5 years after surgery. An increase in cervical myelopathy due to progression of the ossified ligament was observed in only two of 30 patients who could be followed for more than 10 years. Severe surgery-related complications were not observed. Preoperative JOA score, age at the time of surgery, and duration between onset of initial symptoms and surgery affected clinical results.

Conclusions. Mid-term and long-term results of expansive open-door laminoplasty were satisfactory. Considering factors that affected surgical results, early surgery is recommended for OPLL of the cervical spine.