Search PubMed⌕ Search

Biomedical subjects

Alexander R Vaccaro

Publications and source records attributed to Alexander R Vaccaro.

At least 37 records · Page 2Linked to original sources
PubMed2006

Spinal disassociation masquerading as iatrogenic listhesis above a previous fusion.

STUDY DESIGN: A case of remarkable instability adjacent to an L5-S1 fusion is reported. OBJECTIVES: The objective of this study was to review a case of marked instability adjacent to a prior fusion. Diagnostic workup and surgical management options are discussed. SUMMARY OF BACKGROUND DATA: Junctional degeneration above or below the levels of a spinal fusion may be associated with instability. We present an unusual case of instability whose severity was only apparent when the patient was under general anesthesia. MATERIALS AND METHODS: A 52-year-old man with a history of prior L5-S1 fusion presented with severe back pain and lower extremity weakness. Workup including multiple imaging methods revealed junctional degeneration and a Grade I spondylolisthesis at L4-L5 with minimal translation on dynamic imaging. Operative intervention was planned. RESULTS: Intraoperative imaging revealed marked distraction at the L4-L5 disc space not apparent on preoperative dynamic films. The surgical approach was modified accordingly. CONCLUSIONS: Adjacent segment degeneration next to a prior lumbar fusion may be associated with extreme instability. Treatment may require complex stabilization.

Diagnosis, Differential↗
PubMed2006

Measurement techniques for lower cervical spine injuries: consensus statement of the Spine Trauma Study Group.

STUDY DESIGN: Literature review. OBJECTIVES: It was the purpose of the Spine Trauma Study Group to compile a collection of clinically useful imaging methods used in lower cervical spine trauma and to describe in detail how these measurements should be made. SUMMARY OF BACKGROUND DATA: Injury detection, description, and treatment decision-making rely on accurate imaging of the lower cervical spine. However, a standard set of imaging measurement techniques for this region does not exist. While most clinicians have developed their own methods of describing radiographic pathology, this variability often leads to confusion in developing an agreed on classification system and limits treatment recommendations. METHODS: The available literature concerning measurement of injury characteristics after lower cervical trauma was reviewed. Consensus of the most potentially useful measurement methods among the surgeon members of the Spine Trauma Study Group was achieved. RESULTS: These measurements included the following: kyphosis (Cobb angle and posterior vertebral body tangent methods); vertebral body translation; vertebral body height loss; maximal spinal canal compromise and spinal cord compression; facet fracture fragment size; and percentage facet subluxation. CONCLUSIONS: A consistent and standard measurement technique among clinicians with regards to imaging of lower cervical spine trauma should positively influence treatment outcome. However, it is through prospective study that the clinical significance of these recommendations will be scientifically established.

Cervical Vertebrae↗
PubMed2006

Anterior approach to the subaxial cervical spine in children: a brief review.

Although it was originally developed to address degenerative problems, including disc herniations and cervical spondylotic myelopathy in the adult population, the anterior approach to the subaxial spine has proven to be useful for select indications in the pediatric population. The authors review indications for surgery, bone grafting, and instrumentation as they pertain to children.

Bone Transplantation↗
PubMed2006

An evaluation of image-guided technologies in the placement of percutaneous iliosacral screws.

STUDY DESIGN: A surgical simulation study in human cadaver spine specimens was conducted to evaluate the accuracy of 3 different surgical navigation systems compared to standard fluoroscopy in the percutaneous placement of iliosacral screws. OBJECTIVES: To compare the accuracy of percutaneous iliosacral screw placement using standard fluoroscopy, computer-assisted fluoroscopic image guidance, Iso-C3D image guidance (Medtronic Surgical Navigation Technologies, Louisville, CO), and electromagnetic fluoroscopic image guidance. SUMMARY OF BACKGROUND DATA: Conventional percutaneous sacroiliac screw placement has a malposition rate as high as 15%, as reported in the English-speaking literature (Hinsche et al [Clin Orthop Relat Res 2002;395:135-44] and Templeman et al [Clin Orthop Relat Res 1996;329:194-8]). Iso-C3D and computer-assisted image guidance technologies have been proposed to increase this accuracy rate. METHODS: Two iliosacral screws were placed bilaterally (4 screws) in each of 4 cadavers using standard fluoroscopy, computer-assisted fluoroscopic image guidance, Iso-C3D image guidance, and electromagnetic fluoroscopic image guidance. Screw positions were analyzed by computerized tomography after instrumentation and assigned a score based on deviation from ideal screw position. RESULTS: The StealthStation with FluoroNav (Medtronic Surgical Navigation Technologies) appeared to provide the highest accuracy of all guidance techniques. This result was more accurate than standard fluoroscopy. CONCLUSIONS: Computer-assisted fluoroscopy based image navigation appears to be more accurate than standard fluoroscopy in placing these screws. However, errors may occur with all techniques. Further refinement in registration procedures may highly improve the accuracy of percutaneous screw placement in a variety of spinopelvic procedures.

Aged↗
PubMed2006

Osteogenic potential of adult human stem cells of the lumbar vertebral body and the iliac crest.

STUDY DESIGN: Marrow was aspirated from the vertebral body (VB) and iliac crest (IC) of patients undergoing lumbar spinal surgery, following an approved protocol. Progenitor cells were isolated using standard culture conditions and their osteogenic potential evaluated. OBJECTIVE: To evaluate the osteogenic potential of mesenchymal stem cells (MSCs) isolated from the bone marrow of the human VB. SUMMARY OF BACKGROUND DATA: IC marrow grafting during cervical discectomy and fusion procedure is associated with donor site morbidity. Since the VB contains marrow cells, it may be possible to circumvent this problem by using this tissue for osseous graft supplementation. However, there is paucity of information concerning the osteogenic potential of non-IC-derived progenitor cells. Herein, we address this issue. METHODS: Marrow samples from VB of patients undergoing lumbar spinal surgery were collected; marrow was also harvested from the IC. Progenitor cells were isolated and the number of colony forming unit-fibroblastic (CFU-F) determined. The osteogenic potential of the cells was characterized using biochemical and molecular biology techniques. RESULTS: Both the VB and IC marrow generated small, medium, and large sized CFU-F. Higher numbers of CFU-F were obtained from the VB marrow than the IC (P < 0.05). Progenitor cells from both anatomic sites expressed comparable levels of CD166, CD105, CD49a, and CD63. Moreover, progenitor cells from the VB exhibited an increased level of alkaline phosphatase activity. MSCs of the VB and the IC displayed similar levels of expression of Runx-2, collagen Type I, CD44, ALCAM, and ostecalcin. The level of expression of bone sialoprotein was higher in MSC from the IC than the VB. VB and IC cells mineralized their extracellular matrix to a similar extent. CONCLUSIONS: Our studies show that CFU-F frequency is higher in the marrow of the VB than the IC. Progenitor cells isolated from both sites respond in a similar manner to an osteogenic stimulus and express common immunophenotypes. Based on these findings, we propose that progenitor cells from the lumbar vertebral marrow would be suitable candidate for osseous graft supplementation in spinal fusion procedures. Studies must now be conducted using animal models to ascertain if cells of the VB are as effective as those of the IC for the fusion applications.

Bone Marrow Cells↗
PubMed2006

Efficacy of surgical decompression in regard to motor recovery in the setting of conus medullaris injury.

BACKGROUND/OBJECTIVE: An assessment of neurological improvement after surgical intervention in the setting of traumatic conus medullaris injury (CMI). METHODS: A retrospective evaluation of a cohort of patients with a blunt traumatic CMI from T12 to L1. The neurologic and functional outcomes were recorded from the acute hospital admission to the most recent follow-up. Data collected included age, level of injury, neurologic examination according to the Frankel grading system and motor index score, and the mechanism and timing of CMI decompression. RESULTS: A total of 24 patients with a mean age of 27 years (men, 87%) were identified. The most common level of bony injury was L1, and the most frequent mechanism of injury was a motor vehicle crash. Before surgical intervention, 16 of 24 patients (66.7%) had a complete neurological deficit below the level of injury. The median interval from injury to surgery was 6 days (range, 7 hours to 390 days). Decompression, fusion, and adjunctive internal fixation were the most common surgical procedures. Median length of follow-up was 32 months after surgery. Improvement in spinal cord and bladder function was seen in 41.6% and 63.6% of patients, respectively. Root recovery was seen in 83.3% of patients. CONCLUSIONS: In the setting of CMI, no correlation between the timing of surgical decompression and motor improvement was identified. Root recovery was more predictable than spinal cord and bladder recovery.

Adolescent↗
PubMed2006

"Normal" prevertebral soft tissue swelling following elective anterior cervical decompression and fusion.

INTRODUCTION: Prevertebral soft tissue swelling (PSTS) has been evaluated in the setting of traumatic cervical spine injuries. However, no study to date has quantified the PSTS following elective anterior cervical decompression and fusion or the time course to resolution of that swelling. METHODS: From May 2002 to May 2005 the senior author performed 193 elective 1- or 2-level anterior cervical decompression and fusions. Patients who underwent corpectomies and anterior cervical fusions for trauma or tumor were excluded. Preoperative, 2-week postoperative and 6-week postoperative radiographs were available on 100 patients. The prevertebral soft tissue stripe was measured on the neutral lateral radiographs for the 3 time points. The mean swelling (mm) for each time point was calculated and stratified by cervical level. Repeated measures analysis of variance with the Tukey-Kramer multiple comparisons test was used to compare the measured swelling at the various time points. RESULTS: The average PSTS was calculated for each cervical level, for each of the 3 time points, preoperative, 2- and 6-week postoperative. There was a significant increase in PSTS between the preoperative and 2-week postoperative measurements at all levels. There is a significant decrease in PSTS between 2- and 6-week postoperatively at all cervical levels. There is no significant change in PSTS at C2, C3, and C5, when comparing the preoperative and 6-week postoperative measurements. There is significant PSTS at C4, C6, and C7, when comparing preoperative and 6-week postoperative measurements. CONCLUSIONS: The "normal" range for PSTS at 2 weeks and at 6 weeks after elective 1- and 2- level anterior cervical decompression and fusions is described. Our data demonstrates that edema persists at the 2-week follow-up. By 6 weeks postoperative, the increased PSTS has greatly dissipated.

Cervical Vertebrae↗
PubMed2006

Surgical infections in the traumatized spine.

UNLABELLED: Patients with acute spinal injury who require operative intervention may be at increased risk for postoperative surgical-site infection when compared with patients having elective spinal surgery. Various local, systemic, and iatrogenic factors predispose this unique population of patients to post-surgical infection. Nonmodifiable risk factors for surgical-site infection in spine trauma include age, medical comorbidities, and neurologic status. Modifiable risk factors include poor postoperative nutritional status, delay from time of injury to surgical intervention, posterior surgical approach, higher number of levels stabilized, length of postoperative stay in the intensive care unit, and treatment by a single specialty team (versus treatment by successive orthopaedic and neurosurgical teams). When treating patients with spine trauma, a high index of suspicion should be maintained for patients with multiple risk factors for infection and every effort should be made to minimize the modifiable risk factors. LEVEL OF EVIDENCE: Level V (expert opinion). Please see the Guidelines for Authors for a complete description of levels of evidence.

Humans↗
PubMed2006

Validating a newly proposed classification system for thoracolumbar spine trauma: looking to the future of the thoracolumbar injury classification and severity score.

BACKGROUND: Although numerous systems have been proposed, there is no universally accepted classification or scoring system for thoracolumbar spine injuries. Some have gained popularity, but most systems have never been modified or advanced beyond their initial introductory state. To the authors' knowledge, no thoracolumbar classification system has ever been validated in a systematic and scientific manner. STUDY PURPOSE: To critically review previous thoracolumbar classification systems, to discuss the proposal of the new Thoracolumbar Injury Classification and Severity Score (TLICS), to review the steps taken thus far in assessing the reliability of this system, and to discuss plans for future clinical validation of TLICS. METHODS: The authors performed a comprehensive search and analysis of previously published systems for classifying or scoring thoracolumbar spine injuries. Based on the merits and faults of these systems, among other factors, they have developed TLICS. CONCLUSIONS: Of the three phases of validating a fracture classification system described by Audige et al, TLICS has successfully passed through phase 1 (development) and phase 2 (multicenter agreement studies). With modifications made in response to phase 2 studies, TLICS will be ready to enter into the clinical validation phase. Although TLICS will initially be assessed for its ability to predict type of treatment, it is the authors' hope that, with appropriate analysis, the system will also be predictive of injury severity and clinical outcomes. These qualities remain to be demonstrated through rigorous prospective clinical investigation.

Humans↗
PubMed2006

Thoracic paraparesis following an embolic vascular event during lumbar spinal surgery.

OBJECTIVE: A case report illustrating the rare occurrence of thoracic paraparesis following the presumed occurrence of an embolic vascular event during lumbar spinal surgery is presented. The goal is to investigate the potential causes of acute postoperative paraparesis following lumbar spine surgery. A discussion of the symptoms, diagnosis, differential diagnosis, and management of spinal cord ischemia and postembolic infarction is presented. This manuscript is intended to heighten the awareness of the potential for this rare complication to improve the speed and accuracy of diagnosis, allowing the timely institution of appropriate treatment. METHODS: Data analyzed include the patient history, preoperative and postoperative physical examination, clinical course, imaging studies, and input of various consulting services. A review of the English literature on spinal cord ischemia and postembolic infarction was performed. RESULTS: The most likely etiology for the patient's acute postoperative paraparesis appears to be related to an embolic spinal cord infarction. CONCLUSIONS: Management of a spinal cord ischemic event should focus on the following key issues: a prompt diagnosis with timely perioperative imaging studies (magnetic resonance imaging), the attainment of a normotensive state, the institution of systemic anticoagulation if clinically warranted, and maximization of physical function through early rehabilitation.

Aged↗
PubMed2006

Surgical decision making for unstable thoracolumbar spine injuries: results of a consensus panel review by the Spine Trauma Study Group.

OBJECTIVES: The optimal surgical approach and treatment of unstable thoracolumbar spine injuries are poorly defined owing to a lack of widely accepted level I clinical literature. This lack of evidence-based standards has led to varied practice patterns based on individual surgeon preferences. The purpose of this study was to survey the leaders in the field of spine trauma to define the major characteristics of thoracolumbar injuries that influence their surgical decision making. In the absence of good scientific data, expert consensus opinions may provide surgeons with a practical framework to guide therapy and to conduct future research. METHODS: A panel of 22 leading spinal surgeons from 20 level I trauma centers in seven countries met to discuss the indications for surgical approach selection in unstable thoracolumbar injuries. Injuries were presented to the surgeons in a case scenario survey format. Preferred surgical approaches to the clinical scenarios were tabulated and comments weighed. RESULTS: All members of the panel agreed that three independent characteristics of thoracolumbar injuries carry primary importance in surgical decision making: the injury morphology, the neurologic status of the patient, and the integrity of the posterior ligaments. Six clinical scenarios based on the neurologic status of the patient (intact, incomplete, or complete) and on the status of the posterior ligamentous complex (intact or disrupted) were created, and consensus treatment approaches were described. Additional circumstances capable of altering the treatments were acknowledged. CONCLUSIONS: Decision making for the surgical treatment of thoracolumbar injuries is largely dependent on three patient characteristics: injury morphology, neurologic status, and posterior ligament integrity. A logical and practical decision-making process based on these characteristics may guide treatment even for the most complicated fracture patterns.

Algorithms↗
PubMed2006

The use of computerized image guidance in lumbar disk arthroplasty.

OBJECTIVES: Surgical navigation systems have been increasingly studied and applied in the application of spinal instrumentation. Successful disk arthroplasty requires accurate midline and rotational positioning for optimal function and longevity. A surgical simulation study in human cadaver specimens was done to evaluate and compare the accuracy of standard fluoroscopy, computer-assisted fluoroscopic image guidance, and Iso-C3D image guidance in the placement of lumbar intervertebral disk replacements. METHODS: Lumbar intervertebral disk prostheses were placed using three different image guidance techniques in three human cadaver spine specimens at multiple levels. Postinstrumentation accuracy was assessed with thin-cut computed tomography scans. RESULTS: Intervertebral disk replacements placed using the StealthStation with Iso-C3D were more accurately centered than those placed using the StealthStation with FluoroNav and standard fluoroscopy. Intervertebral disk replacements placed with Iso-C3D and FluoroNav had improved rotational divergence compared with standard fluoroscopy. Iso-C3D and FluoroNav had a smaller interprocedure variance than standard fluoroscopy. These results did not approach statistical significance. Relative to both virtual and standard fluoroscopy, use of the StealthStation with Iso-C3D resulted in improved accuracy in centering the lumbar disk prosthesis in the coronal midline. CONCLUSIONS: The StealthStation with FluoroNav appears to be at least equivalent to standard fluoroscopy and may offer improved accuracy with rotational alignment while minimizing radiation exposure to the surgeon. Surgical guidance systems may offer improved accuracy and less interprocedure variation in the placement of intervertebral disk replacements than standard fluoroscopy. Further study regarding surgical navigation systems for intervertebral disk replacement is warranted.

Aged↗
PubMed2006

Cytokine assay of the epidural space lavage in patients with lumbar intervertebral disk herniation and radiculopathy.

INTRODUCTION: Lumbar disk herniation may result in a radiculopathic pattern of symptoms. Consideration for a primary biochemical inducement of pain over a mechanical mechanism is a contemporary topic of spinal research. However, the exact pathomechanism by which a degenerative intervertebral disk leads to neural inflammation and pain has not been determined. Using modern techniques of chemical analysis, biochemical markers can be identified which participate in the degenerative cascade, and possibly with the onset of pain. The purpose of this research is to identify potential biochemical markers through a novel technique of epidural space lavage that may be helpful in understanding the pathogeneses of pain in the presence of intervertebral disk degeneration and herniation. METHODS: Fifty consecutive patients with acute radiculopathy secondary to a symptomatic herniated lumbar intervertebral disk or spinal stenosis, and who were indicated for epidural steroid injection were identified. Additionally, 3 volunteers with no history of back pain or radiculopathy volunteered to undergo epidural lavage. After needle insertion, a lavage followed by fluid aspiration of the epidural space at the level of the disc herniation, in the case of the symptomatic patients, was performed using normal saline, before the instillation of corticosteroids. The fluid samples were frozen at -20 degrees C until analysis. A biochemical evaluation for a battery of cytokines was undertaken (IL-1beta, IL-1ra, IL-2, IL-2R, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12p40, IL-13, IL-15, IL-17, TNF-alpha, IFN-alpha, IFN-gamma, GM-CSF, MIP-1alpha, MIP-1beta, IP-10, MIG, Eotaxin, RANTES, and MCP-1, and neuropeptides) using high-resolution multiplex bead immunoassays and enzyme-linked immunosorbent assay (ELISA). Additionally, polyacrylamide gel electrophoresis was carried out to verify the presence of serum proteins. RESULTS: Despite the presence of amino acids/serum proteins in the epidural lavage fluid, none of the aforementioned mediators were isolated in a quantifiable concentration using the ELISA techniques with >5 pg/mL resolution. DISCUSSION: The current proteomics array technology was not able to detect critical levels of biochemical markers present in the epidural space through the mentioned lavage technique. This lack of detection could be due to the absence of the factors in this environment or the inability of the technique to obtain or detect factors which may be present. CONCLUSION: Although a novel approach, the current study was unable to identify the presence of a series of inflammatory peptides in the epidural lavage of patients with symptomatic radicular pain due to herniated disc disease. We recommend alternative experimental designs than the one we pursued for definitively identifying potential sources of pain generators.

Acute Disease↗
PubMed2006

Confusion regarding mechanisms of injury in the setting of thoracolumbar spinal trauma: a survey of The Spine Trauma Study Group (STSG).

The Spine Trauma Study Group (STSG) developed the thoracolumbar injury severity score to direct the management of thoracolumbar spine injuries. The original system is based on 3 variables: the mechanism of injury as determined by imaging studies, the integrity of the posterior ligamentous complex, and the neurologic status of the patient. Considerable controversy exists among treating physicians in classifying injury mechanisms. The purpose of this study was to survey the STSG on case examples related to the mechanism of thoracolumbar injury. A 2-question survey regarding thoracolumbar injury mechanisms and scoring was distributed to members of the STSG. A total of 27 STSG members completed surveys on defining and scoring thoracolumbar injury mechanisms. Data from these completed surveys were analyzed using a 2-tailed Fisher exact test on a chi2 contingency table. Sixty-seven percent of physicians preferred a definition incorporating posterior ligamentous complex disruption without posterior vertebral body retropulsion over the location of the axis of rotation in differentiating flexion-distraction from advanced stage flexion-compression injuries, representing a statistically significant difference (P=0.0285). There was no statistical consensus on the scoring emphasizing a primary and secondary mechanism of injury in complex injury patterns. Despite the statistical consensus to 1 survey question, there seems to be no dominating opinion on distinguishing thoracolumbar injury mechanisms. Perhaps identifying objective findings on imaging studies and clinical examination in place of guessing injury mechanisms may allow for a more reliable and valid thoracolumbar injury classification system.

Attitude of Health Personnel↗
PubMed2006

Agreement between orthopedic surgeons and neurosurgeons regarding a new algorithm for the treatment of thoracolumbar injuries: a multicenter reliability study.

INTRODUCTION: Considerable variability exists in the management of thoracolumbar (TL) spine injuries. Although there are many influences, one significant factor may be the treating surgeon's specialty and training (ie, orthopedic surgery vs. neurosurgery). Our objective was to assess the agreement between spinal orthopedic and neurologic surgeons in rating the severity of TL spine injuries with a new treatment algorithm. This information could be important in establishing consensus-based protocols for managing these challenging injuries. METHODS: Twenty-eight spinal surgeons (8 neurosurgeons and 20 orthopedic surgeons) reviewed 56 TL injury case histories. Each case was classified and scored according to the TL injury severity score (TLISS). The case histories were reordered and the physicians repeated the exercise 3 months later. At both intervals the surgeons were asked if they agreed with the final treatment recommendation of the TLISS algorithm. The reliability and decision validity of the TLISS was compared. RESULTS: Between-group interrater reliability was similar to within group reliabilities. Intrarater reliability was also similar between groups. The between speciality interrater reliability of the TLISS management recommendation was moderate (74% agreement, kappa=0.532). Orthopedic and neurosurgeons agreed with the TLISS management recommendation 91.4% and 94.4% of the time, respectively. CONCLUSIONS: The TLISS demonstrated good reliability in terms of intraobserver and interobserver agreement on the algorithmic treatment recommendations. The recommendation for operation seems to be consistent between fellowship-trained orthopedic and neurosurgical spine surgeons. This type of classification system may reduce the existing variability and initial management decision for treatment of TL injuries.

Algorithms↗
PubMed2006

Intrarater and interrater reliability and validity in the assessment of the mechanism of injury and integrity of the posterior ligamentous complex: a novel injury severity scoring system for thoracolumbar injuries. Invited submission from the Joint Section Meeting On Disorders of the Spine and Peripheral Nerves, March 2005.

OBJECT: A new classification and treatment algorithm for thoracolumbar injuries was recently introduced by Vaccaro and colleagues in 2005. A thoracolumbar injury severity scale (TLISS) was proposed for grading and guiding treatment for these injuries. The scale is based on the following: 1) the mechanism of injury; 2) the integrity of the posterior ligamentous complex (PLC); and 3) the patient's neurological status. The reliability and validity of assessing injury mechanism and the integrity of the PLC was assessed. METHODS: Forty-eight spine surgeons, consisting of neurosurgeons and orthopedic surgeons, reviewed 56 clinical thoracolumbar injury case histories. Each was classified and scored to determine treatment recommendations according to a novel classification system. After 3 months the case histories were reordered and the physicians repeated the exercise. Validity of this classification was good among reviewers; the vast majority (> 90%) agreed with the system's treatment recommendations. Surgeons were unclear as to a cogent description of PLC disruption and fracture mechanism. CONCLUSIONS: The TLISS demonstrated acceptable reliability in terms of intra- and interobserver agreement on the algorithm's treatment recommendations. Replacing injury mechanism with a description of injury morphology and better definition of PLC injury will improve inter- and intraobserver reliability of this injury classification system.

Algorithms↗