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STUDY DESIGN This is a prospective cohort study. OBJECTIVE To characterize the accuracy of patient recollection of preoperative symptoms after cervical spine surgery. SUMMARY OF BACKGROUND DATA Recall bias is a well-known source of systematic error. The accuracy of patient recall after cervical spine surgery remains unknown. METHODS Consecutive patients undergoing cervical spine surgery for myelopathy or radiculopathy were enrolled. Neck and arm numeric pain scores and Neck Disability Indices were recorded preoperatively. Patients were asked to recall their preoperative status at either short (

STUDY DESIGN Prospective cohort study. OBJECTIVE To characterize the accuracy of patient recollection of preoperative symptoms after lumbar spine surgery. SUMMARY OF BACKGROUND DATA Although patient-reported outcomes have become important in the evaluation of spine surgery patients, the accuracy of patient recall remains unknown. METHODS Patients undergoing lumbar decompression with or without fusion were enrolled. Back and leg Numeric Pain Scores and Oswestry Disability Indices were recorded preoperatively. Patients were asked to recall their preoperative status at a minimum of 1 year after surgery. Actual and recalled scores were compared using paired t tests and relations were quantified using Pearson correlation coefficients. Multivariable linear regression was used to identify factors that affected recollection. RESULTS Sixty-two patients with a mean age of 66.1 years were included. Compared to their preoperative scores, patients showed significant improvement in back pain (mean difference [MD] = -3.2, 95% CI -4.0 to -2.4), leg pain (MD -3.3, 95% CI -4.3 to -2.2), and disability (MD -25.0%, 95% CI -28.7 to -19.6). Patient recollection of preoperative status was significantly more severe than actual for back pain (MD +2.3, 95% CI 1.5-3.2), leg pain (MD +1.8, 95% CI 0.9-2.7), and disability (MD +9.6%, 95% CI 5.6-14.0). No significant correlation between actual and recalled scores with regards to back (r = 0.18) or leg (r = 0.24) pain and only moderate correlation with disability (r = 0.44) were seen. This was maintained across age, sex, and time between date of surgery and recollection. More than 40% of patients switched their predominant symptom from back pain to leg pain or leg pain to back pain on recall. CONCLUSION Relying on patient recollection does not provide an accurate measure of preoperative status after lumbar spine surgery. Recall bias indicates the importance of obtaining true baseline scores and patient-reported outcomes prospectively and not retrospectively. LEVEL OF EVIDENCE 2.

Study design Retrospective review. Objective To evaluate key risk factors for the development of C5 palsy after cervical corpectomy, including resection of the posterior longitudinal ligament (PLL). Summary of background data Postoperative C5 palsy is a well-known complication after cervical spine surgery. It is unknown whether resection of the PLL affects the incidence of C5 palsy. Methods We performed a retrospective review of 459 consecutive patients undergoing anterior cervical corpectomies over a 15-year period. Medical records were reviewed to gather demographic data, operative details, and the incidence of C5 palsy. We performed regression analyses to identify variables that predicted the development of C5 palsy. Results Our final analysis included 397 patients (females 51.4%, mean age 55.6 ± 11.6 yrs). Anterior corpectomy alone was performed in 255 (64.2%) patients, and combined anterior and posterior fusion was performed in 142 (35.8%) patients. Twenty-four patients (6.0%) developed C5 nerve palsy. Univariable regression demonstrated age greater than 65 (odds ratio, OR 2.7, 95% confidence interval, CI 1.2 to 6.3), corpectomy of three or more levels (OR 6.3, 95% CI 2.1 to 18.9), presence of ossification of the PLL (OR 4.3, 95% CI 1.6 to 11.7), and complete or partial resection of the PLL (OR 2.6, 95% CI 1.0 to 6.7) predicted development of C5 palsy. Multivariable regression demonstrated that the odds of getting C5 palsy with complete or partial resection of the PLL is 4.0 times (95% CI 1.5 to 10.5) higher compared with patients with an intact PLL. There were no significant differences in C5 palsy rates based on surgical approach (anterior vs. anterior plus posterior), sex, smoking status, or diabetes. Conclusion Age greater than 65 years, corpectomy of three or more levels, presence of ossification of the PLL, and complete or partial resection of the PLL significantly predicted the development of C5 palsy. Level of evidence 4.

MISS techniques have gained recent popularity. The proposed benefits of these techniques include reduced tissue trauma, reduced blood loss, less perioperative pain, and a quicker recovery and return to normal activities. The purpose of this study was to evaluate the accuracy of intraoperative computed tomography (CT)-based navigation for placement of percutaneous pedicle screws in a cadaveric model. Outcome measures included accuracy of screw placement. Two cadaveric specimens were utilized. CT images were obtained using an O-Arm (Medtronic, Memphis, Tennessee, United States) and were coupled to the Stealth navigation system (Medtronic). Computer navigation was used for placement of percutaneous pedicle screws. Screws were placed bilaterally from T5 to S1. Postinsertion CT scans were obtained. Pedicle breach was assessed and classified (I: none, II: 4 mm) with direction of breach. Thirty thoracic screws were placed with 3 (10%) medial breaches and 17 (56.7%) lateral breaches (grade III). Of 20 lumbar screws there were 0 medial breaches and 2 (10%) lateral breaches (1 grade III, 1 grade IV). Four sacral screws were placed without breaches. The real-time computer-aided navigation tool (“simulated screw”) was limited in identifying a breach. Manipulation of the surgeon's hand or driver could change the orientation of the navigation tool without changing the screw trajectory. CT-based navigation for percutaneous pedicle screw placement appears safe for the lumbar spine. Lateral thoracic breaches appeared commonly but were not felt to be clinically significant. The 10% rate of medial thoracic breach was concerning, but definitive conclusions could not be made due to the small sample size.

Study design Retrospective review of 750 consecutive multilevel cervical spine decompression surgeries performed by a single spine surgeon. Objective To determine the incidence of C5 palsy in a large consecutive series of multilevel cervical spine decompression procedures. Summary of background data Palsy of the C5 nerve is a well-known potential complication of cervical spine surgery with reported rates ranging from 0% to 30%. The etiology remains uncertain but has been attributed to iatrogenic injury during surgery, tethering from shifting of the spinal cord, spinal cord ischemia, and reperfusion injury of the spinal cord. Methods We included patients undergoing multilevel cervical corpectomy, corpectomy with posterior fusion, posterior laminectomy and fusion, and laminoplasty. Exclusion criteria included lack of follow-up data, spinal cord injury preventing preoperative or postoperative motor testing, or surgery not involving the C5 level. Incidence of C5 palsy was determined and compared to determine whether significant differences existed among the various procedures, patient age, sex, revision surgery, preoperative weakness, diabetes, smoking, number of levels decompressed, and history of previous upper extremity surgery. Results Of the 750 patients, 120 were eliminated on the basis of the exclusion criteria. The 630 patients included in the analysis consisted of 292 females and 338 males. The mean age was 58 years (range, 19-87). The incidence of C5 nerve palsy for the entire group was 42 of 630 (6.7%). The incidence was highest for the laminectomy and fusion group (9.5%), followed by the corpectomy with posterior fusion group (8.4%), the corpectomy group (5.1%), and finally the laminoplasty group (4.8%), although these differences did not reach statistical significance. There was a significantly higher incidence in males (8.6% vs. 4.5%, P = 0.05). Conclusion Incidence of C5 nerve palsy after cervical spine decompression was 6.7%. This is consistent with previously published studies and represents the largest series of North American patients to date. There is no statistically significant difference in incidence of C5 palsy based on surgical procedure, although there was a trend toward higher rates with laminectomy and fusion.

Background context Surgical indications for lumbar burst fracture remain controversial. Potential indications for surgery include 50% canal compromise, 50% loss of vertebral height, 30° of kyphosis, and posterior element fracture or disruption of the posterior ligamentous complex. Different surgical approaches are available depending on fracture characteristics. It is possible that a minimally invasive approach could allow for a safe and effective treatment with fewer comorbidities than the traditional open technique. Purpose This is a report of an L3 burst fracture treated with a minimally invasive approach for anterior corpectomy and posterior pedicle screw fixation. Study design Case report. Patient sample Patient with L3 burst fracture. Outcome measures Radiographs and computed tomography scans to evaluate for fusion and evaluation of pain and neurologic function. Methods A 30-year-old male was involved in a head-on motor vehicle collision. Initial imaging revealed an L3 burst fracture with 60% canal compromise, 50% loss of vertebral body height, a large anteriorly displaced fragment consisting of 40% of the vertebral body depth, and a facet fracture. Surgical decompression and stabilization were recommended for this patient because of radiographic signs of instability. After medical clearance and consent, the patient underwent a minimally invasive L3 corpectomy and L2–L4 interbody fusion through a direct lateral approach with placement of a titanium mesh cage filled with local autograft and allograft bone matrix. The patient then underwent a percutaneous stabilization with pedicle screw fixation from L2 to L4. Results The patient was ambulating on the first postoperative day, and pain was controlled with oral analgesics. Intraoperative blood loss was less than 100 cc. He was discharged to a rehabilitation facility on the second postoperative day. Postoperatively, he complained of some left lower extremity pain and numbness. The pain completely resolved by the 6-month follow-up visit. The numbness in the anterolateral left thigh was improved but not completely resolved at 12 months. He continued to have full strength in all extremities. Conclusion The traditional approach to an anterior lumbar corpectomy and posterior pedicle screw fixation involves significant postoperative pain and frequent ileus. This minimally invasive approach allowed for early mobilization, resumption of diet, and discharge from the hospital on postoperative day two.

Study design We evaluated 43 patients diagnosed with tandem spinal stenosis (TSS) from 1999 to 2005 in an academic hospital. Objective The purpose of this study is to compare outcomes after simultaneous decompression of the cervical and lumbar spine versus staged operations. Summary of background data TSS is a rare degenerative disease affecting multiple spinal levels with limited research describing operative management. Methods Of our patients, 21 underwent simultaneous decompression of both the cervical and lumbar spine and 22 underwent staged decompression of the cervical spine followed by the lumbar spine at a later date. Medical records were reviewed for patient demographics, type and duration of symptoms, operative time, combined blood loss, cervical myelopathy modified Japan Orthopaedic Association Score, Oswestry Disability Index (ODI), major and minor complications, and average length of follow up. Each category was evaluated by Pearson correlations and unpaired Student t tests. Results With a mean follow-up of 7 years, both groups improved in JOA and ODI without a significant difference between the 2 operative groups in terms of major or minor complications, JOA, or ODI. Independent of the surgical algorithm, age above 68 years, estimated blood loss ≥400 mL, and operative time ≥150 minutes significantly increased the number of complications. Conclusions These results indicate that TSS can be effectively managed by either surgical intervention, simultaneous, or staged decompressions. However, patient age, blood loss, and operative time do significantly impact outcomes. Therefore, operative management should be tailored to the patient's age and the option which will limit blood loss and operative time, whether that is by simultaneous or staged procedures.

Study design The aim of this study is to characterize the anatomy of vertebral arteries using magnetic resonance imaging scans of 250 consecutive patients. Objectives To document the prevalence of midline vertebral artery (VA) migration in a subgroup of patients presenting with neck pain, radiculopathy, or myelopathy and to identify the course of the VA through the TFs. Summary of background data Knowledge of VA anomalies and their respective prevalence may help surgeons decrease the incidence of iatrogenic injury to this artery. Methods In this retrospective review of 281 consecutive patients, who had an magnetic resonance imaging for axial neck pain, radiculopathy, or myelopathy, anatomic measurements were obtained from C2 to C7. Results The observed VA anomalies can be classified into following 3 main groups: (1) intraforaminal anomalies-midline migration, (2) extraforaminal anomalies, and (3) arterial anomalies. Midline migration of the VA was identified in 7.6% (19/250) of patients. The etiology can be degenerative or traumatic. It is important to note that the pattern of medial migration was clockwise rotation from caudal to cephalad and was present in all of our patients with anomalous arteries. Additionally, at C6, only 92% (460/500) of VAs were located within their respective transverse foramens and hypoplastic VAs were identified in 10% (25/250) of patients. Conclusion Anomalies that must be considered before surgery include interforamenal anomalies, extraforamenal anomalies, and arterial anomalies. The intraforaminal anomalies involve midline migration, which places the VA at direct risk during corpectomy. Extraforaminal anomalies are related to VAs entering the transverse foramen at a level other than C6, which can increase the risk of injury during the anterior approach to the cervical spine. Arterial anomalies can be fenestrated, hypoplastic, or absent. These raise concern with the ability to maintain cerebral perfusion in the setting of damage to one of the VAs with the presence of contralateral arterial abnormality.

STUDY DESIGN This is a case report of a posterior extrusion of the polyethylene core from a CHARITE arthroplasty. This is the first reported case of posterior dislocation of the polyethylene and the revision strategies used to correct this problem. OBJECTIVE To report a novel failure mechanism and revision strategy for CHARITE total disc arthroplasty (TDA). SUMMARY OF BACKGROUND DATA Case report at a Level 1 tertiary care referral center in the northeastern United States. METHODS This is a case report and review of the literature of a patient who sustained posterior dislocation of the polyethylene core from a CHARITE TDA several months after the index procedure. RESULTS Core dislocation is a known complication of TDA. However, of the known reported dislocations all have been anterior. This case describes the first known occurrence of posterior core dislocation and the revision strategy for this problem. CONCLUSION This case report highlights the first known case of a posterior dislocation of a CHARITE core. It is likely that altered biomechanical forces generated over time attributed to device failure. An instrumented posterior fusion with removal of the core is what ultimately led to a stable revision construct.

Study design Retrospective radiographic analysis. Objective To retrospectively review a group of patients undergoing anterior cervical discectomy and fusion (ACDF) to determine the relative risk of adjacent level disc degeneration after incorrect needle localization. Summary of background data The needle puncture technique is a well-established method to cause disc degeneration in experimental animal studies. The risk for accelerated degeneration because of needle puncture in humans is unknown. Methods A retrospective radiographic analysis of 87 consecutive patients after single or 2-level ACDF with anterior plate instrumentation was performed. Perioperative and follow-up radiographs were used to grade disc degeneration according to a previously described scale. Results Eighty-seven patients were included in the study (36 underwent 1-level ACDF, and 51 underwent 2-level ACDF). Seventy-two had correct needle localization at the level of planned surgery; 15 had incorrect needle localization (1 level above the operative level). There were no differences between the 2 groups in age, sex and length of follow-up. Patients in the incorrectly marked group were statistically more likely to demonstrate progressive disc degeneration with an odds ratio of 3.2. There was no correlation between age and length of follow-up with development of disc degeneration. Conclusion There is a 3-fold increase in risk of developing adjacent level disc degeneration in incorrectly marked discs after ACDF at short-term follow-up. This may indicate that either needle related trauma or unnecessary surgical dissection contributes to accelerated adjacent segment degeneration.

Previous investigators have reported on benefits and risks associated with vertebroplasty and kyphoplasty, but there are limited comparison data available. Additionally, much of the data is from retrospective studies and case series.The purpose of this study is to review the literature and perform a meta-analysis of pain relief and risk of complications associated with vertebroplasty versus kyphoplasty.A meta-analysis of the literature on effectiveness of pain control and risk of complications after vertebroplasty versus balloon kyphoplasty. Outcomes measures include visual analog scale and complications.A comprehensive review of the literature was performed. All studies providing information on pain relief and complications were included. Preoperative, postoperative, and change in visual analog scale (VAS) scores were tabulated. Data were analyzed to identify if a significant improvement in the VAS score occurred. Changes in the VAS scores were compared for vertebroplasty and kyphoplasty to determine if there was a significant difference.A total of 1,036 abstracts were identified. Of these, 168 studies met the inclusion criteria. Mean pre- and postoperative VAS scores for vertebroplasty were 8.36 and 2.68, respectively, with a mean change of 5.68 (p.001). The mean pre- and postoperative VAS scores for kyphoplasty were 8.06 and 3.46, respectively, with a mean change of 4.60 (p.001). There was statistically greater improvement found with vertebroplasty versus kyphoplasty (p.001). The risk of new fracture was 17.9% with vertebroplasty versus 14.1% with kyphoplasty (p.01). The risk of cement leak was 19.7% with vertebroplasty versus 7.0% with kyphoplasty (p.001).Both vertebroplasty and kyphoplasty provided significant improvement in VAS pain scores. Vertebroplasty had a significantly greater improvement in pain scores but also had statistically greater risk of cement leakage and new fracture.

Study Design. Anatomic study of the internal carotid artery (ICA) location with respect to C1 based on computed tomography (CT) scans with contrast medium. Objective. To measure the location of the ICA relative to the anterior aspect of C1 to assess the risk of placing C1–C2 transarticular or C1 lateral mass screws. Summary of Background Data. Vertebral artery injury is a known risk from placement of screws in C1. A previous case report revealed an ideally placed C1–C2 transarticular screw abutting and narrowing the ICA. The risk of ICA injury from C1 screws is unknown. Methods. Fifty random head and neck CT scans with contrast medium were retrospectively analyzed. Measurements were taken bilaterally including the closest distance from the ICA lumen to C1 and the distance from the medial edge of the ICA to a line drawn along the medial border of the foramen transversarium. The risk of inserting bicortical C1–C2 transarticular and C1 lateral mass screws was estimated based on these measurements. Results. The mean distance from the ICA to C1 was 2.88 mm on the left and 2.89 mm on the right. The ICA lumen was medial to the foramen transversarium in 42 (84%) of 50 cases (mean: 2.78 mm on the left and 3.00 mm on the right). The proximity of the ICA to C1 posed moderate risk in 46% of cases and high risk in 12% (on at least one side). Conclusion. Because of the risk of ICA injury from a drill bit or the tip of a bicortical screw, we recommend preoperative CT scan with contrast medium in all cases in which a screw is to be placed into C1. If the ICA is in close proximity to the anterior border of C1, unicortical fixation or a different fusion technique should be considered.

STUDY DESIGN A questionnaire survey. OBJECTIVE To characterize surgeons' current perspectives on the administration of methylprednisolone for acute spinal cord injury (SCI) and determine how this has changed during the last 7 years. SUMMARY OF BACKGROUND DATA The determinants of and complications associated with off-label steroid use for acute SCI remain controversial. METHODS A survey was sent to surgeon members of the Cervical Spine Research Society requesting information regarding their use of steroids for acute SCI. Determinants included surgeons' specialty, trauma center level, number of SCIs treated per year, severity of injury, and location of injury. These results were compared across groups as well as with a historical control. RESULTS In the case of cervical complete and incomplete SCIs, 47.4% and 56.4% of respondents, respectively, reported using steroids. For complete and incomplete thoracolumbar spine injuries, the usage rate was 46.2% and 55.1%, respectively. There has been a significant (P < 0.0001) decrease in the number of surgeons using high-dose steroids in the treatment of acute SCIs when compared with a previous report in 2006 (56% vs. 89%).More than 80% of respondents reported sepsis, active gastrointestinal bleeding, and SCI occurring earlier than 8 hours as contraindications. Seventy-one percent of respondents reported observing complications from the use of steroids, and 76.3% thought that the complications were severe enough to limit steroid use. Of the surgeons who used steroids for SCI, 26% thought that steroids improved neurological recovery, 19.2% used steroids to adhere to institutional protocol, and 25.6% stated they did not think steroids were beneficial but used them because of medicolegal concerns. CONCLUSION There has been a significant decrease in the number of surgeons using high-dose steroids for acute SCIs. Sepsis, gastrointestinal bleeding, and an injury occurring more than 8 hours prior to presentation were agreed upon as contraindications to steroid use.

Study Design. A biomechanical study was designed to assess relative construct stabilities of modern anterior thoracolumbar instrumentations in a calf spine model with an anterior and middle column defect. Objectives. The purpose is to compare the biomechanical stability of various anterior fixation devices in an unstable calf spine model. Summary of Background Data. Modern types of anterior thoracolumbar instrumentations evolved to either rods or plates. Biomechanical properties and comparative studies of these instrumentations are lacking. Methods. Twenty fresh calf spines (L2-L5) were used for the biomechanical tests. L2 and L5 vertebrae were used to attach the loading and base frames, respectively. Specimens underwent nondestructive biomechanical tests performed using a three-dimensional motion measuring system. In each specimen, three different cases were tested : intact spine, anterior fixation with an interbody graft after total discectomy and end-plate excision of L3-L4 disc, anterior fixation only without the graft. Four anterior fixators, University Anterior Plating System, the Kaneda device, the Z-plate, and Texas Scottish Rite Hospital system were used. Each device was tested on five specimens. A polymethyl-methacrylate block was inserted into the disc space to simulate the interbody grafting, and a fixation device was implanted with axial compression. Rotational angles of the L3-L4 segment stabilized by a fixation device and graft were normalized by the corresponding angles of the intact specimen to study the overall stabilizing effects. Results. With the interbody graft and fixation devices, all showed significant stabilizing effects in flexion, extension, and lateral bending. All devices restored axial rotation stability to intact specimen, but only the Kaneda device restored the torsional stability beyond the intact specimen. No statistical differences in stabilizing effects in axial rotation were found between any of the tested devices. When the graft was removed, the Kaneda device significantly decreased the motions in all directions compared with the intact motion, whereas the University plate decreased the motions in flexion, extension, and lateral bending. The Texas Scottish Rite Hospital system was found to reduce the flexion and lateral bending motions significantly, and Z-plate decreased lateral bending motions only. Stabilizing effects of the interbody graft were significant in lateral bendings for all devices. Additionally, the significant stabilizing role of the graft was noted in flexion and extension in Z-plate only. The graft did not significantly reduce the axial rotation motion in any instrumentations. Conclusions. Modern anterior instrumentations for the thoracolumbar spine, such as the Kaneda device, Texas Scottish Rite Hospital system, Z-plate, and University plate, restored the stability in all motions when an interbody graft was inserted. The stability of fixation devices revealed that the Kaneda device is the best, particularly in restoring the torsional stability. The information on the relative stability provided by different instrumentations should help the spine surgeon in choosing the appropriate instrumentation for the particular circumstance.

Study design Observational. Objective To estimate the radiation dose imparted to patients during typical thoracolumbar spinal surgical scenarios. Summary of background data Minimally invasive techniques continue to become more common in spine surgery. Computer-assisted navigation systems coupled with intraoperative cone-beam computed tomography (CT) represent one such method used to aid in instrumented spinal procedures. Some studies indicate that cone-beam CT technology delivers a relatively low dose of radiation to patients compared with other x-ray-based imaging modalities. The goal of this study was to estimate the radiation exposure to the patient imparted during typical posterior thoracolumbar instrumented spinal procedures, using intraoperative cone-beam CT and to place these values in the context of standard CT doses. Methods Cone-beam CT scans were obtained using Medtronic O-arm (Medtronic, Minneapolis, MN). Thermoluminescence dosimeters were placed in a linear array on a foam-plastic thoracolumbar spine model centered above the radiation source for O-arm presets of lumbar scans for small or large patients. In-air dosimeter measurements were converted to skin surface measurements, using published conversion factors. Dose-length product was calculated from these values. Effective dose was estimated using published effective dose to dose-length product conversion factors. Results Calculated dosages for many full-length procedures using the small-patient setting fell within the range of published effective doses of abdominal CT scans (1-31 mSv). Calculated dosages for many full-length procedures using the large-patient setting fell within the range of published effective doses of abdominal CT scans when the number of scans did not exceed 3. Conclusion We have demonstrated that single cone-beam CT scans and most full-length posterior instrumented spinal procedures using O-arm in standard mode would likely impart a radiation dose within the range of those imparted by a single standard CT scan of the abdomen. Radiation dose increases with patient size, and the radiation dose received by larger patients as a result of more than 3 O-arm scans in standard mode may exceed the dose received during standard CT of the abdomen. Understanding radiation imparted to patients by cone-beam CT is important for assessing risks and benefits of this technology, especially when spinal surgical procedures require multiple intraoperative scans.

STUDY DESIGN: This is a prospective study. OBJECTIVE: The aim of our study is to identify whether vertebral arteries (VA), normal or aberrant, are routinely described in cervical spine magnetic resonance imaging (MRI) interpretations. SUMMARY OF BACKGROUND DATA: VA injury is a serious complication of anterior cervical spine surgery. Aberrant VA anatomy is a potential cause of such complications. Therefore, VA anatomy should be evaluated in cervical MRIs. METHODS: Six neuroradiologists were blinded to the study design and were asked to interpret 79 cervical MRIs. Of these, 39 had aberrant VAs, whereas 40 had normal VAs. Initially, the indications for the study included only a description of patient's symptoms. The radiologists were then given the same MRIs with different indications. This time, the indications included the patient's symptoms, a request for annotations on the VA, and a definition of VA anomaly. All of the MRI interpretations were then evaluated for the frequency and accuracy of VA description. RESULTS: When the indications for the study did not specifically request a comment on VAs, the VA was never described (0%). When the indications included the specific request and definition, all 6 commented on the VA (100%). Three of the 6 radiologists were 100% accurate in identifying all 40 normal and 39 aberrant VAs, whereas the other 3 identified all 40 normal and 38 of 39 aberrant VAs. CONCLUSION: This study demonstrates that the VA is not a standard component of cervical spine MRI interpretations. Because of the significant complications related to its injury, VA anatomy, whether normal or variant, needs to be evaluated in cervical MRIs. When ordering a cervical MRI, surgeons should request a description of the VA and any anomalies.

STUDY DESIGN Meta-analysis. OBJECTIVE Meta-analysis of the data to determine the effect of magnetic resonance imaging (MRI) signal change on preoperative and postoperative Japanese Orthopedic Association (JOA) scores and on recovery rate after surgery. SUMMARY OF BACKGROUND DATA MRI signal changes are commonly found in myelopathy. There is often an increased T2 signal with or without a decreased T1 signal. The clinical significance of these signal changes remains debated. METHODS A comprehensive review of the literature was performed to identify all published studies with data on the presence of MRI signal change and JOA scores in myelopathic patients. T tests were performed to determine if there were significant differences between preoperative and postoperative JOA scores in patients with or without MRI signal change. The recovery rate was calculated for all patients undergoing surgery. T tests were performed to determine whether significant differences occurred in recovery rate in patients with or without MRI signal change. RESULTS A total of 16 studies were used for the meta-analysis. The total population included 886 patients: 659 with MRI signal change, and 227 without MRI signal change. Preoperative and postoperative JOA scores and the recovery rates were significantly better in patients without MRI signal changes (P < 0.05). The mean preoperative JOA scores were 10.63 and 11.37 for patients with and without MRI signal changes, respectively. The mean postoperative JOA scores were 13.37 and 14.19 for patients with and without MRI signal changes, respectively. The mean recovery rates were 43.87% and 49.31% for patients with and without MRI signal changes, respectively. CONCLUSION A meta-analysis of the literature revealed statistically better preoperative and postoperative JOA scores and recovery rates following surgery in myelopathic patients without MRI signal change. Although the data were statistically significant, the clinical significance of the differences might be less due to the relatively small differences in actual values.

Study design Experimental dog model of acute spinal cord injury. Objective To compare the relative value of methylprednisolone, surgical decompression, or both for the treatment of traumatic spinal cord injury. Summary of background data Acute spinal cord injury results from both primary damage to the spinal cord at the time of the initial injury as well as a deleterious secondary cascade of events, which leads to further damage. Surgical decompression is known to improve clinical outcomes, but the timing of surgical decompression remains controversial. Methods A nylon tie was used to constrict the spinal cord in 18 adult male beagle dogs. The animals were then prospectively randomized to 3 groups: 1) surgical decompression at 6 hours and intravenous methylprednisolone; 2) surgical decompression at 6 hours and intravenous saline; and 3) intravenous methylprednisolone without surgical decompression. Each animal was evaluated by somatosensory-evoked potentials, daily neurologic assessment, and histologic examination at 2 weeks following injury. Results Immediately following spinal cord constriction, all animals were paraplegic, incontinent, and the somatosensory-evoked potentials were abolished. Surgical decompression 6 hours after injury, with or without methylprednisolone, led to significantly better neurologic function at 2 weeks than methylprednisolone alone. Conclusion In the setting of acute and persistent spinal cord compression in beagle dogs, surgical decompression 6 hours after injury, with or without methylprednisolone, is more effective for improving neurologic recovery than methylprednisolone alone.

Background context Cervical spine dislocations represent an area of great controversy among spine surgeons. Purpose The purpose of this review is to present the specific areas of controversy and to provide a review of the literature. Study design A case of cervical spine dislocation is presented to illustrate the major controversies related to the treatment of cervical spine dislocations. Methods A review of the literature is presented regarding the major controversial aspects of the treatment of cervical spine dislocations. Results The major areas of controversy include the choice of imaging, closed versus open reduction and surgical approach. Conclusions Guidelines for the management of cervical spine dislocations are presented based on evidence-based medicine.

Study design Biomechanical study of pullout strength of unicortical versus bicortical C1 lateral mass screws using a cadaveric cervical spine model. Objective To compare pullout strength of unicortical versus bicortical C1 lateral mass screws. Summary of background data The internal carotid artery and hypoglossal nerve lie over the anterior aspect of the lateral mass of the atlas and are at risk from bicortical C1 lateral mass screws. Unicortical screws would reduce the risk of injury to these neurovascular structures; however, no data are available on the relative strength of unicortical versus bicortical C1 lateral mass screws. Methods Fifteen cadaveric cervical spine specimens underwent axial pullout testing of C1 lateral mass screws. A unicortical C1 lateral mass screw was placed on 1 side with a contralateral bicortical screw. Results The mean pullout strengths of the unicortical screws and bicortical screws were 588 N (range, 212 to 1234 N) and 807 N (range, 163 to 1460 N), respectively (P=0.008). Conclusions Bicortical C1 lateral mass screws were significantly stronger than unicortical screws; however, the mean pullout strength of both the unicortical and bicortical C1 screws were greater than previously reported values for subaxial lateral mass screws. On the basis of these data, the clinical necessity for using bicortical screw fixation in all patients must be questioned. If similar strength can be achieved using unicortical C1 lateral mass screw to that currently accepted in the subaxial spine, bicortical screws might not be justified for the C1 lateral mass. However, the ability to extrapolate C1-C2 data to subaxial spine data is uncertain because of the difference in normal physiologic loading at these levels.

Background context The internal carotid artery and hypoglossal nerve lie over the anterior aspect of the lateral mass of the atlas and are at risk from bicortical C1–C2 transarticular screws. This has led to the recommendation for unicortical screws if the neurovascular structures are in close proximity to the proposed exit point. No data are available on strength of unicortical versus bicortical C1–C2 transarticular screws. Purpose To compare the biomechanical pullout strength of unicortical versus bicortical C1–C2 transarticular screws in a cadaveric model. Study design Biomechanical study. Methods Fifteen cervical spine specimens underwent axial pullout testing. A unicortical C1–C2 transarticular screw was placed on one side with a contralateral bicortical screw. Data were analyzed to reveal any significant differences in strength. Results Mean pullout strength for the bicortical C1–C2 transarticular screws was 1,048.8 (±360.1) N versus 939.2 (±360.6) for unicortical screws (p=.22). There was no significant difference in the pullout strength of unicortical and bicortical screws. Conclusions In cases with satisfactory bone quality, it appears reasonable to use unicortical screws to avoid the risk of neurovascular injury from penetrating the anterior cortex of C1.

Study design A questionnaire survey. Objective Estimate the use and justification of the steroid protocol for spinal cord injury (SCI) patients. Summary of background data There remains significant debate over clinical benefits and potential complications of the steroid protocol for SCI patients. Methods A survey was sent to spine surgeons requesting information on 1) specialization, 2) trauma center affiliation, 3) use of steroid protocol, 4) justification of using steroid protocol, and 5) SCI volume. Results Responses were received from 305 surgeons. Fourteen (4.6%) surgeons used steroids only if initiated before their consult, 262 (85.9%) would initiate if within the accepted 8-hour timeframe, 20 (6.6%) did not use steroids at all, and 9 (3.0%) used a different protocol. Justification for steroids use: 65 improved recovery, 64 institutional protocol, 110 medicolegal reasons, and 26 did not personally initiate steroids. Eighteen surgeons listed both clinical benefit and institutional protocol, and 22 others listed both institutional protocol and medicolegal reasons. Conclusions The majority (90.5%) of responding surgeons used the steroid protocol; however, only 24.1% used the steroid protocol due to a belief in improved clinical outcomes.

Background context Acute onset of radicular symptoms has been reported following hemorrhage into lumbar synovial cysts after trauma or in cases of spinal instability. No previous cases have been linked to anticoagulation therapy. Purpose To present a case of symptomatic hemorrhagic lumbar synovial cyst occurring after anticoagulation therapy. Study design A case report and review of the literature. Methods A patient presented with low back and radicular pain secondary to a large synovial facet cyst. Magnetic resonance imaging revealed a large facet cyst compressing the thecal sac and L3 exiting nerve root. Results The synovial cyst was excised during a lumbar decompression and fusion. Gross blood was present in the cyst. Conclusions This is the first reported case of symptomatic hemorrhagic lumbar facet cyst associated with anticoagulation therapy.

Study design Biomechanical flexibility tests were performed using calf and human cadaveric lumbar spine models to investigate the effect of anatomic differences. Objectives The purpose is to determine if differences exist in biomechanical flexibility testing results between calf and human cadaveric spines when using identical methods and instrumentation. Summary of background data Calf spines are commonly used in biomechanical research as a substitute for human cadaveric spines in an attempt to reduce expense and specimen variability. Despite widespread use, the validity of this model has not been thoroughly investigated. Methods Five fresh calf spines and five human cadaveric spines (L2-L5) were used for nondestructive biomechanical flexibility testing. Maximum moments of 6.4 Nm were achieved in five increments of 1.6 Nm. The rotations of L3 with respect to L4 were measured in 5 cases: 1) intact; 2) following partial discectomy, including partial laminectomy and partial facetectomy; 3) partial discectomy with pedicle screw instrumentation; 4) total discectomy with pedicle screw instrumentation; and 5) pedicle screw instrumentation with interbody graft. Rotational angles were normalized to the intact case to determine the stabilizing effect during each testing case. Data were analyzed using analysis of variance to determine if significant differences existed between the calf spine results and the human cadaveric spine results. Results In both models, motion increased following discectomy, decreased with instrumentation, and increased with total discectomy. Placement of the interbody graft decreased motion during axial rotation, flexion, and extension but increased lateral bending motion. A two-way analysis of variance revealed no significant differences in the two models during flexion or extension (P > 0.05), but significant differences were discovered in axial rotation and lateral bending (P Conclusions Significant differences were identified in flexibility testing between calf and human cadaveric specimens. The calf spine model overestimated the stabilizing effect of instrumentation during lateral bending and underestimated stability during axial rotation. The extrapolation of calf spine data to the in vivo case, especially during axial rotation and lateral bending, should carefully consider the variation between these two models.

STUDY DESIGN A prospective analysis of variations in monthly spinal infection rates at a spinal cord injury center with resident and fellow involvement in surgical care. OBJECTIVE To analyze the association between resident and fellow participation in spinal surgery and the incidence of perioperative wound infection over the academic year. SUMMARY OF BACKGROUND DATA It has been hypothesized that resident and fellow participation in surgical procedures may account for increased wound complications. Previous spinal infection studies have not addressed variations in the incidence of perioperative wound infections over the academic year. METHODS All cases of postoperative spinal infections at a spinal cord injury center from January 1994 through December 1997 were analyzed to determine whether monthly variations reflect the changes in surgical house officer experience through the academic year. RESULTS A statistically significant (P < 0.027) increase in the incidence of spinal infection was demonstrated for the month of January. No other significant variations in the monthly incidence of spinal infection existed. No significant differences were found when the data were analyzed: year-to-year (P < 0.727), season-to-season (P < 0.204), 4-month resident rotation (P < 0.061), and 6-month fellow rotation (P < 0.075). CONCLUSION A significantly higher incidence of spinal infection (10.5%) was observed for the month of January. Because January does not represent the start of a new resident or fellow rotation, there appears to be no association between the incidence of perioperative spinal wound infections and the level of experience of the surgical house officers in a regional spinal cord injury center.

Background context Coccydynia is a painful condition of the terminal portion of the spine often resulting from direct trauma, childbirth or unknown etiology. This is a relatively rare condition with no universally accepted treatment protocol. Purpose To more clearly determine the optimal treatment for patients with coccydynia and to assess the outcomes after conservative and surgical therapy. Study design Retrospective review of outcomes of all patients presenting with symptoms of coccydynia during a 5-year period. Patient sample Thirty-two patients presented to an orthopedic spine surgeon during a 5-year period with symptoms of coccydynia. Outcome measures Patients completed visual analog pain scales (VAS) and the Oswestry (OSW) functional capacity index. Methods Of the 32 patients in the study, 4 (13%) were treated with nonsteroidal anti-inflammatory drugs (NSAIDs) alone, 17 (53%) were treated with NSAIDs followed by local injections and 11 (34%) underwent coccygectomy after failure of NSAIDs and local injections. Patients completed VAS and OSW forms. Pain drawings were also completed. Results Patients undergoing surgery had significantly greater pretreatment VAS scores (8.3 vs 5.4, p = .002). Surgical patients also had greater OSW scores, but not significantly (36.6 vs 24.2, p = .223). Marked improvement was reported by 9 of 11 (82%) surgical patients. Three of 11 (27%) surgical patients developed wound infections and 1 (9%) wound dehiscence. All infections resolved following irrigation and debridement and a short course of oral antibiotics. Conclusions Patients with coccydynia should be managed conservatively when possible. Treatment should include NSAIDs and local steroid injections. Patients will often require repeat injections over time. Surgery can offer reasonable results for patients failing conservative treatment, but they should be warned of the high rate of infection.

The Bagby and Kuslich (BAK) interbody fusion system has been shown to be a safe and effective method for obtaining solid fusion while maintaining lumbar lordosis. Although postoperative cage loosening has been reported, intraoperative cage loosening has not. The authors describe three cases in which BAK cages became loosened during operation. After the first BAK cage was inserted, it appeared to be well positioned and firmly seated; after placement of the second cage, however, the first cage was loose. Each of these cages was replaced without incident and appeared well placed on follow-up. It is crucial for the surgeon to verify that all cages are firmly seated before closure. This may reduce the incidence of postoperative cage migration.

STUDY DESIGN A three-dimensional, noninvasive motion analysis method was developed by monitoring the orientation of the principal axes of each vertebra. OBJECTIVES To develop a method of performing three-dimensional, noninvasive motion analysis of the spine using computed tomography data. SUMMARY OF BACKGROUND DATA The concept of using principal axes of the moment of inertia tensor to measure the orientation and position of a rigid body has been applied to the wrist and subtalar joints, but has not yet been applied to the spine. METHODS Scans were taken of two isolated vertebrae in various known positions. Centroids, area, moments, and product of inertia of each scan were determined using a commercial program. Custom software combined data using the parallel axis theorem to give three-dimensional data for each vertebra. Changes in the centroid and principal axes were used to calculate translation and rotation, respectively. RESULTS The system accuracy was within 1.0 degree in rotation and 1.0 mm in translation. Some errors occurred in minor motions when a smaller number of scans were used. System resolution was 0.43 mm. CONCLUSIONS A system has been developed capable of calculating three-dimensional spinal motion based on measurements of a series of computed tomography images. The system has an accuracy similar to that of current motion analysis methods, but future studies will be necessary to apply this system in vivo.

Study Design. The biomechanical role of transfixation in pedicle screw instrumentation was investigated using flexibility tests and finite element analyses. Objective. To assess the stabilizing effect of use and position of transfixators. Summary of Background Data. Transfixation is common in pedicle screw instrumentation, however, its biomechanical role and optimal position are not completely understood. Methods. Specimens underwent nondestructive flexibility tests using a three-dimensional motion analysis system. Tests compared the intact spine with instrumentation with and without transfixators. Rotational angles of the superior vertebra, resulting from the maximum moment of 6.4 Nm, were compared. Three-dimensional finite element models investigated transfixator position. Rotations of the superior vertebra were compared for cases with and without transfixators to determine the position providing the greatest stability. Results. Biomechanical test showed that only axial rotational stability significantly improved with transfixators compared with instrumentation alone. Finite element models predicted improvement in lateral bending and axial rotation with transfixators compared with the case with no transfixator. With one transfixator, the greatest improvement in axial rotation stability occurred with the transfixator at the proximal 1/4 position of the rods. When two transfixators were used, the optimal locations were with one transfixator in the middle and the second at the proximal 1/8 position. Conclusions. Transfixators improved the stabilizing effects of pedicle screw instrumentation. The greatest axial rotation stability was obtained with two transfixators; one in the middle and the other at the proximal 1/8 position of the longitudinal rods.

Purpose of study: Coccydynia is a painful condition of the terminal portion of the spine often resulting from direct trauma, childbirth or unknown etiology. This is a relatively rare condition with no universally accepted treatment protocol. These patients present a unique challenge to the spinal surgeon. Methods used: Thirty-two patients presented with coccydynia during a 5-year period. Patients included eight men (25%) and 24 women (75%). Mean age was 47 years (range, 23 to 72 years). Thirteen (41%) reported a history of a fall involving direct trauma to the coccyx, 3 (9%) were related to pregnancy, 2 (6%) were related to motor vehicle accidents and 14 (44%) had no identifiable cause. of findings: Seventeen (53%) patients received local injections, 4 (13%) received nonsteroidal anti-inflammatory drugs (NSAIDs) and 11 (34%) underwent coccygectomy. The mean visual analog scale pain score was 6.4 (range, 1.5 to 10), and the mean Oswestry score was 27.3% (range, 0% to 62%). Patients receiving surgery had significantly greater pain scores (8.3 vs. 5.4, p=.002). They also had greater Oswestry scores, although there was no significant difference (33.6 vs. 24.2, p=.223). Of 11 surgical patients, 5 (45%) reported significant pain relief, 5 (45%) moderate pain relief and 1 (9%) no pain relief. Of 17 patients treated with injections, 11 (65%) reported significant pain relief, 5 (29%) moderate pain relief and 1 (6%) no improvement. Of 4 patients treated with NSAIDs, all reported significant improvement. Of 11 surgical patients, there were 3 wound infections (27%) and 1 wound dehiscence (9%). All infections resolved following I & D and a short course of oral antibiotics. Relationship between findings and existing knowledge: Specific patient factors have been associated with coccydynia patients, including female gender, fall on the buttocks, obesity and a possibility of psychological disorder. Our results showed a similar association with female gender (75%) and history of a recent fall (41%). We showed a tendency of patients to be overweight with a mean BMI of 27, but there was no association between the BMI and the severity of the patient's symptoms. No patients in our study had positive Waddell's tests. Overall significance of findings: Patients with coccydynia should be managed conservatively when possible. Treatment should include NDAIDs and local steroid injections. Patients will often require repeat injections over time. Surgery can offer reasonable results for patients failing conservative treatment, but they should be warned of the high rate of infection. Disclosures: No disclosures. Conflict of interest: No conflicts.

Magnetic resonance (MR) imaging is considered the gold standard for soft-tissue disease. The traditional MR imaging series uses axial and sagittal views. The purpose of this study was to demonstrate that oblique MR imaging provides valuable information about the cervical foramen not available from the conventional MR imaging technique. Ten asymptomatic individuals volunteered for MR imaging. Measurements were taken of height, width, and area for the nerves and foramen at the entrance and mid zones. Nerves were graded as normal, contacted, or deformed. Normal foraminal morphology in asymptomatic individuals and characteristics that compromise the space available for the nerve root were identified. Nerves with minimal or no contact had significantly greater foraminal widths than nerves with significant contact. Although there was a correlation between nerve contact and foraminal width, regression analysis did not demonstrate a correlation between disc height and foraminal size.