bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vitro biomechanical analysis of three anterior thoracolumbar implants
Authors: Hitchon Patrick W. , Goel Vijay K. , Rogge Thomas N. , Torner James C. , Dooris Andrew P. , Drake John S. , Yang S. J. , Totoribe Koji 
Published: May 2009

Object. The goal of this study was to evaluate the comparative efficacy of three commonly used anterior thoracolumbar implants: the anterior thoracolumbar locking plate (ATLP), the smooth-rod Kaneda (SRK), and the Z-plate.
Methods. In vitro testing was performed using the T9—L3 segments of human cadaver spines. An L-1 corpectomy was performed, and stabilization was achieved using one of three anterior devices: the ATLP in nine spines, the SRK in 10, and the Z-plate in 10. Specimens were load tested with 1.5-, 3-, 4.5-, and 6-Nm in flexion and extension, right and left lateral bending, and right and left axial rotation. Angular motion was monitored using two video cameras that tracked light-emitting diodes attached to the vertebral bodies. Testing was performed in the intact state in spines stabilized with one of the three aforementioned devices after the devices had been fatigued to 5000 cycles at ± 3 Nm and after bilateral facetectomy.
There was no difference in the stability of the intact spines with use of the three devices. There were no differences between the SRK- and Z-plate—instrumented spines in any state. In extension testing, the mean angular rotation (± standard deviation) of spines instrumented with the SRK (4.7 ± 3.2°) and Z-plate devices (3.3 ± 2.3°) was more rigid than that observed in the ATLP-stabilized spines (9 ± 4.8°). In flexion testing after induction of fatigue, however, only the SRK (4.2 ± 3.2°) was stiffer than the ATLP (8.9 ± 4.9°). Also, in extension postfatigue, only the SRK (2.4 ± 3.4°) provided more rigid fixation than the ATLP (6.4 ± 2.9°). All three devices were equally unstable after bilateral facetectomy. The SRK and Z-plate anterior thoracolumbar implants were both more rigid than the ATLP, and of the former two the SRK was stiffer.
Conclusions. The authors' results suggest that in cases in which profile and ease of application are not of paramount importance, the SRK has an advantage over the other two tested implants in achieving rigid fixation immediately postoperatively.
Lasting paraplegia caused by loss of lumbar spinal cord interneurons in rats: no direct correlation with motor neuron loss
Authors: Hadi Bassam , Zhang Y. Ping , Burke Darlene A. , Shields Christopher B. , Magnuson David S. K. 
Published: May 2009

Object. The aims of this study were to investigate further the role played by lumbar spinal cord interneurons in the generation of locomotor activity and to develop a model of spinal cord injury suitable for testing neuron replacement strategies.
Methods. Adult rats received intraspinal injections of kainic acid (KA). Locomotion was assessed weekly for 4 weeks by using the Basso, Beattie, and Bresnahan (BBB) 21-point locomotor scale, and transcranial magnetic motor evoked potentials (MMEPs) were recorded in gastrocnemius and quadriceps muscles at 1 and 4 weeks. No changes in transcranial MMEP latency were noted following KA injection, indicating that the descending motor pathways responsible for these responses, including the alpha motor neurons, were not compromised. Rats in which KA injections included much of the L-2 segment (10 animals) showed severe locomotor deficits, with a mean BBB score of 4.5 ± 3.6 (± standard deviation). Rats that received lesions rostral to the L-2 segment (four animals) were able to locomote and had a mean BBB score of 14.6 ± 2.6. Three rats that received only one injection bilaterally centered at L-2 (three animals) had a mean BBB score of 3.2 ± 2. Histological examination revealed variable loss of motor neurons limited to the injection site. There was no correlation between motor neuron loss and BBB score.
Conclusions. Interneuron loss centered on the L-2 segment induces lasting paraplegia independent of motor neuron loss and white matter damage, supporting earlier suggestions that circuitry critical to the generator of locomotor activity (the central pattern generator) resides in this area. This injury model may prove ideal for studies of neuron replacement strategies.
New approach to cervical flexion deformity in ankylosing spondylitis
Authors: Duff Sarah E. , Grundy Paul L. , Gill Steven S. 
Published: May 2009

✓ The treatment of cervical fixed flexion deformity in ankylosing spondylitis presents a challenging problem that is traditionally managed by a corrective cervicothoracic osteotomy. The authors report a new approach to this problem that involves performing a two-level osteotomy at the level of maximum spinal curvature, thereby achieving complete anatomical correction in a one-stage procedure.
This 48-year-old woman with ankylosing spondylitis presented with a 30-year history of progressive neck deformity that left her unable to see ahead and caused her to experience difficulty eating, drinking, and breathing on exertion. On examination, she exhibited a 90° fixed flexion deformity of the cervical spine, which was maximum at C-4; this was confirmed on imaging studies.
A two-level osteotomy was performed at C3–4 and C4–5 around the area of maximum spinal curvature, and the deformity was corrected by extending the head on its axis of rotation through the uncovertebral joints. The spine was stabilized using a Ransford loop. An excellent anatomical position was achieved, as was complete correction of the deformity.
A two-level midcervical osteotomy performed at the level of maximum spinal curvature in ankylosing spondylitis enables complete correction of severe fixed flexion deformity in a single procedure. Preservation of the uncovertebral joints allows smooth and safe correction of the deformity about their axis of rotation.
Intraoperative computerized tomography scanning to assess the adequacy of decompression in anterior cervical spine surgery
Authors: Freidberg Stephen R. , Pfeifer Bernard A. , Dempsey Peter K. , Tarlov Edward C. , Dube Michael A. , Day John D. , Machado Darlene E. 
Published: May 2009

Object. The purpose of this study was to improve the accuracy of bone removal during anterior spinal surgery. Intraoperative computerized tomography (CT) scanning was used to assess the success of bone resection and permit immediate correction in the event of inadequate bone removal.
Methods. The Phillips Tomoscan M was used to obtain preoperative cervical scans before and after cervical bone resection was complete. The completeness of bone removal was assessed by the operating neurosurgeon by reviewing the postresection CT scan. If the bone removal was deemed inadequate, additional bone was removed using a high-speed drill. A CT scan was obtained after each subsequent decompression until adequate bone removal was achieved.
In 31 patients undergoing anterior cervical decompression intraoperative CT scanning was performed. Nineteen patients underwent corpectomy and 12 discectomy. Of the 31 patients, assessment of intraoperative CT scans obtained in 17 indicated further bone removal was required.
Conclusions. Intraoperative CT scanning to monitor bone removal during anterior cervical surgery is a valuable tool to ensure the adequacy of surgery.
Results and risk factors for anterior cervicothoracic junction surgery
Authors: Boockvar John A. , Philips Matthew F. , Telfeian Albert E. , O'Rourke Donald M. , Marcotte Paul J. 
Published: May 2009

Object. Stabilization of the cervicothoracic junction (CTJ) requires special attention to the operative approach and biomechanical requirements of the fixation construct. In this study the authors assess the morbidity associated with the anterior approach to the CTJ and define risks that may lead to construct failure after anterior CTJ surgery.
Methods. Data obtained for 14 patients (six men and eight women, mean age 50.1 years) who underwent surgical stabilization of the CTJ via an anterior cervical approach were retrospectively reviewed to assess the anterior approach—related morbidity and the risks of construct failure. The mean follow-up period was 21.1 months. Four patients (29%) had previously undergone CTJ surgery; in 11 patients (64%) more than one motion segment was involved (two levels, six patients; three levels, four patients; four levels, one patient); allograft was placed in three (21%) of 14 graft sites; and anterior plates were used for reconstruction augmentation in eight patients (57%). Postoperatively all patients improved, although four patients had residual deficits or pain. Graft/plate failure, requiring surgical revision and/or halo placement, occurred in five patients (36%). One patient experienced transient recurrent laryngeal nerve palsy. Postoperatively, the authors classified patients into one of two groups: those in whom surgery was successful (nine cases) and those in whom it had failed (five cases). Analysis of the characteristics of these two groups revealed that male sex (p < 0.0365), multiple levels of involvement (p < 0.0378), and the use of allograft as compared with autograft (p < 0.0088) were significant risk factors for construct failure. Prior CTJ surgery (p < 0.053) tended to be associated with graft failure.
Conclusions: Findings of this study, in the setting of these factors, indicate that anterior reconstruction alone may not meet the biomechanical needs of this spinal region and that supplementary fixation may be considered to augment stabilization for fusion success.
Metastatic renal cell carcinoma of the spine: surgical treatment and results
Authors: Jackson Robert J. , Gokaslan Ziya L. , Arvinloh Shang-Chuin 
Published: May 2009

Object. Renal cell carcinoma (RCC) is an aggressive malignancy that frequently metastasizes. When RCC metastasizes to the spine, significant pain and neurological dysfunction often follow. Because systemic therapy and radiotherapy have a limited effect in controlling spinal disease, surgery is frequently required; however, there are very few published series specifically addressing the role and benefits of the surgical treatment for this disease. The authors conducted a retrospective study to review their experience with the surgical treatment of metastatic RCC of the spine, paying particular attention to methodology and patient neurological status, pain relief, and survival.
Methods. Between January 1993 and April 1999, 79 patients (63 men and 16 women patients; average age 55 years, range 16–82 years) underwent 107 spinal operations for metastatic RCC. Indications for surgery included disabling pain (94 [88%] of 107 procedures) and/or neurological dysfunction (55 [51%] of 107 procedures). The anatomical location and extent of tumor determined the choice of an anterior, posterior, or combined surgical approach. Internal fixation was performed in all but three patients. Preoperative embolization was required in approximately one half of the patients. Radiotherapy was performed in 40 patients prior to surgery, and immuno- and chemotherapy were administered in 70 patients either pre- or postoperatively. After an average follow-up duration of 15 months, 57 patients had died. Kaplan—Meier analysis revealed a median postoperative survival of 12.3 months. Significant pain reduction, as indicated by a visual analog pain scale, was achieved in 84 (89%) of the 94 cases presenting with disabling pain. Neurological improvement was seen in 36 (65%) of the 55 patients. The major morbidity and 30-day mortality rates were 15% (16 of 107 procedures) and 2% (two of 107 procedures), respectively.
Conclusions. In selected patients with metastatic RCC of the spine, resection followed by stabilization can provide pain relief and neurological preservation or improvement.
Use of pedicle screw fixation in the management of malignant spinal disease: experience in 100 consecutive procedures
Authors: Fourney Daryl R. , Abi-Said Dima , Lang Frederick F. , McCutcheon Ian E. , Gokaslan Ziya L. 
Published: May 2009

Object. Few reports are available on the use of pedicle screw fixation for cancer-related spinal instability. The authors present their experience with pedicle screw fixation in the management of malignant spinal column tumors.
Methods. Records for patients with malignant spinal tumors who underwent pedicle screw fixation at the authors' institution between September 1994 and December 1999 were retrospectively reviewed.
Results. Ninety-five patients with malignant spinal tumors underwent 100 surgeries involving pedicle screw fixation: metastatic spinal disease was present in 81 patients, and locally invasive tumors were demonstrated in 14 patients. Indications for surgery were pain (98%) and/or neurological dysfunction (80%). A posterior (48%) or a combined anterior—posterior (52%) approach was performed depending on the extent of tumor and the patient's condition. At the mean follow up of 8.2 months, 43 patients (45%) had died; median survival, as determined by Kaplan—Meier analysis, was 14.8 months. At 1 month postsurgery, self-reported pain had improved in 87% of cases (p < 0.001), which is a finding substantiated by reductions in analgesic use, and 29 (47%) of 62 patients with preoperative neurological impairments were functionally improved (p < 0.001). Postoperative complications were associated only with preoperative radiation therapy (p = 0.002) and with preexisting serious medical conditions (p = 0.04). In two patients asymptomatic violation of the lateral wall of the pedicle was revealed on postoperative radiography. The 30-day mortality rate was 1%.
Conclusions. For selected patients with malignant spinal tumors, pedicle screw fixation after tumor resection may provide considerable pain relief and restore or preserve ambulation with acceptable rates of morbidity and mortality.
Biomechanics of Grade I degenerative lumbar spondylolisthesis. Part 1: In vitro model
Authors: Crawford Neil R. , Çagli Sedat , Sonntag Volker K. H. , Dickman Curtis A. 
Published: May 2009

Object. The authors sought to create and to evaluate an in vitro model of Grade I degenerative (closed-arch) spondylolisthesis.
Methods. The model of spondylolisthesis was created by two primary procedures: 1) resection of the disc; and 2) stripping of anterior and posterior longitudinal ligaments away from the vertebral bodies (VBs). In 13 vertebral levels obtained from three cadaveric lumbar spines, the tissues were resected sequentially in alternating order to determine the relative contribution of each resection to spinal instability. The entire specimens were loaded with nonconstraining torques and then individual levels were loaded with anteroposterior shear forces. The motion values were measured optoelectronically for each specimen at individual levels.
Conclusions. The integrity of the disc was more important than attachment of the ligaments to the VB, but the resection of both structures was necessary to achieve substantial destabilization. The structures of the spine are highly resilient, and destabilization is difficult to achieve without performing extensive resection. Using the techniques described in this paper to alter normal spines, a level of spinal instability (Grade I; 25% slippage) that may represent spondylolisthesis can be modeled in vitro.
Biomechanics of Grade I degenerative lumbar spondylolisthesis. Part 2: Treatment with threaded interbody cages/dowels and pedicle screws
Authors: Çagli Sedat , Crawford Neil R. , Sonntag Volker K. H. , Dickman Curtis A. 
Published: May 2009

Object. The authors sought to determine the biomechanical effectiveness of threaded interbody cages or dowels compared with that achieved using pedicle screw instrumentation in resisting Grade I lumbar spine degenerative spondylolisthesis.
Methods. Thirty-three levels obtained from seven cadaveric lumbar spines were instrumented with cages or dowels, pedicle screw/rod instrumentation, or both. Entire specimens were loaded with nonconstraining torques. Each level was loaded with anteroposterior shear forces while an optical system was used to measure the specimen's motion at individual levels.
Pedicle screw/rods outperformed interbody cages and dowels in treating spondylolisthesis. Cages or dowels alone provided only moderate biomechanical stability, and their effectiveness depended heavily on the integrity of the ligaments and remaining annulus, whereas the success of pedicle screw fixation relied predominantly on the integrity of the bone for solid fixation. Little biomechanical difference was demonstrated between cages and dowels; both devices were susceptible to loosening with cyclic fatigue.
Conclusions. Biomechanically, cages or dowels alone were suboptimal for treating lumbar spondylolisthesis, especially compared with pedicle screw/rods. Threaded cages or dowels used together with pedicle screws/rods created the most stable construct.
Distribution of genes for bone morphogenetic protein—4, —6, growth differentiation factor—5, and bone morphogenetic protein receptors in the process of experimental spondylosis in mice
Authors: Bunakase Takano , Ariga Kenta , Miyamoto Shimpei , Okuda Shin'ya , Tomita Tetsuya , Iwasaki Motoki , Yonenobu Kazuo , Yoshikawa Hideki 
Published: May 2009

Object. Because little is known about the molecular mechanisms underlying the process of spondylosis, the authors examined the extent of genetic localization of several members of bone morphogenetic protein (BMP) and BMP receptors in chondrogenesis during the process of inducing spondylosis in their previously established experimental mice model.
Methods. Experimental spondylosis was induced in 5-week-old ICR mice. The cervical spine was harvested chronologically, and histological sections were prepared. Messenger RNA for BMP-4, growth and differentiation (GDF)—5, BMP-6, and BMP receptors (ALK-3, -6, and BMP-RII) was localized in the tissue sections by in situ hybridization.
In the early stage, BMP-4—derived mRNA was localized mainly in cells in the anterior margin of the cervical discs, together with ALK-6 and BMP-RII mRNA. No GDF-5 and BMP-6 mRNA was detected at this stage. In the late stage, cells positive for BMP-4 decreased, whereas GDF-5 and BMP-6 mRNA were localized in cells undergoing chondrogenesis. The ALK-3 mRNA began to appear in this stage, as did ALK-6 and BMP-RII.
Conclusions. The localization of transcripts for BMP-4, -6, and GDF-5 as well as BMP receptors shown during the present experimental model indicate the possible involvement of molecular signaling by these BMPs in the chondrogenic progress in spondylosis.
The effects of dexamethasone on bone fusion in an experimental model of posterolateral lumbar spinal arthrodesis
Authors: Sawin Paul D. , Dickman Curtis A. , Crawford Neil R. , Melton M. Stephen , Bichard William D. , Sonntag Volker K. H. 
Published: May 2009

Object. The use of corticosteroid agents during the healing phase after spinal arthrodesis remains controversial. Although anecdotal opinion suggests that corticosteroids may inhibit bone fusion, such an effect has not been substantiated in clinical trials or laboratory investigations. This study was undertaken to delineate the effect of exogenous corticosteroid administration on bone graft incorporation in an experimental model of posterolateral lumbar fusion.
Methods. An established, well-validated model of lumbar intertransverse process spinal fusion in the rabbit was used. Twenty-four adult New Zealand white rabbits underwent L5–6 bilateral posterolateral spinal fusion in which autogenous iliac crest bone graft was used. After surgery, the animals were randomized into two treatment groups: a control group (12 rabbits) that received intramuscular injections of normal saline twice daily and a dexamethasone group (12 rabbits) that received intramuscular dexamethasone (0.05 mg/kg) twice daily. After 42 days, the animals were killed and the integrity of the spinal fusions was assessed by radiography, manual palpation, and biomechanical testing.
In seven (58%) of the 12 control rabbits, solid posterolateral fusion was achieved. In no dexamethasone-treated rabbits was successful fusion achieved (p = 0.003). Tensile strength and stiffness of excised spinal segments were significantly lower in dexamethasone-treated animals than in control animals (tensile strength 91.4 ± 30.6 N and 145.3 ± 48.2, respectively, p = 0.004; stiffness 31.4 ± 11.6 and 45.0 ± 15.2 N/mm, respectively, p = 0.02).
Conclusions. The corticosteroid agent dexamethasone inhibited bone graft incorporation in a rabbit model of single-level posterolateral lumbar spinal fusion, inducing a significantly higher rate of nonunion, compared with that in saline-treated control animals.
Innervation of caudal denervated ventral roots and their target muscles by the rostral spinal motoneurons after implanting a nerve autograft in spinal cord—injured adult marmosets
Authors: Liu Song , Aghakhani Nozar , Boisset Nazaire , Said Gérard , Tadie Marc 
Published: May 2009

Object. The authors conducted a study to determine the effects of using a nerve autograft (NAG) to promote and guide axonal regrowth from the rostral spinal cord to the caudal lumbar ventral nerve roots to restore hindlimb motor function in adult marmosets after lower thoracic cord injury.
Methods. Nine animals underwent a left-sided hemisection of the spinal cord at T-12 via left-sided T9—L3 hemilaminectomy, with section of all ipsilateral lumbrosacral ventral nerve roots. In the experimental group (five animals), an NAG obtained from the right peroneal nerve was anastomosed with the sectioned and electrophysiologically selected lumbar ventral roots (left L-3 and L-4) controlling the left quadriceps muscle and then implanted into the left ventrolateral T-10 cord. In the control group (four animals), the sectioned/selected lumbar ventral roots were only ligated.
After surgery, all marmosets immediately suffered from complete paralysis of their left hindlimb. Five months later, some clinical signs of reinnervation such as tension and resistance began to appear in the paralyzed quadriceps of all experimental animals that received autografts. Nine months postoperatively, three of the five experimental marmosets could maintain their lesioned hindlimb in hip flexion. Muscle action potentials and motor evoked potentials were recorded from the target quadriceps in all experimental marmosets, but these potentials were absent in the control animals. Horseradish peroxidase retrograde labeling from the distal sectioned/reconnected lumbar ventral roots traced 234 ± 178 labeled neurons in the ipsilateral T8–10 ventral horn, mainly close to the NAG tip. Histological analysis showed numerous regenerating axons in this denervated/reconnected nerve root pathway, as well as newly formed motor endplates in the denervated/reinnervated quadriceps. No axonal regeneration was detected in the control animals.
Conclusions. These data indicate that the rostral spinal neurons can regrow into the caudal ventral roots through an NAG, thereby innervating the target muscle in adult marmosets after spinal cord injury.