Category: Spine

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No Justification for Cervical Disk Prostheses in Clinical Practice: A Meta-Analysis of Randomized Controlled Trials

Neurosurgery 66:1153-1160, 2010 DOI: 10.1227/01.NEU.0000369189.09182.5F

A meta-analysis was performed to evaluate whether a beneficial clinical effect of cervical disk prostheses over conventional cervical diskectomy with fusion exists.

METHODS: A literature search was completed ending February 4, 2009, that included the abstract books of recent major spine congresses. All studies reported the results of singlelevel cervical disease without myelopathy. The Visual Analog Score (VAS) of the arm, VAS of the neck, Neck Disability Index, Physical Composite Scores of the Short Form 36, and Mental Composite Score of the Short Form 36, as well as adverse events, were evaluated.

RESULTS: Nine records were found, totaling 1533 patients. Of these, 1165 were evaluable at the last follow-up at 12 or 24 months. As an effect measure, a pooled odds ratio (OR) was calculated at 12 and 24 months. At 12 months, the VAS arm reached statistical significance (OR = 0.698; 95% confidence interval [CI], 0.571-0.853), as did the VAS neck (OR = 0.690; 95% CI, 0.562-0.847), and the Physical Composite Scores (OR = 1.362; 95% CI, 1.103-1.682) and the Mental Composite Score (OR = 1.270; 95% CI, 1.029-1.569) of the Short Form 36, favoring arthroplasty. The Neck Disability Index at 24 months also reached statistical difference (OR = 0.794; 95% CI, 0.641-0.984). All other measurements did not reveal any statistical difference. The number of complications, including secondary surgeries for adjacent segment disease, did not differ.

CONCLUSION: A clinical benefit for the cervical disk prosthesis is not proven. Because none of the studies were blinded, bias of the patient or researcher is a probable explanation for the differences found. Therefore, these costly devices should not be used in daily clinical practice.

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Microdecompressive Laminatomy With a 5-year Follow-up Period for Severe Lumbar Spinal Stenosis

J Spinal Disord Tech 2010;23:229–235

Study Design: The 2 groups of patients with severe lumbar spinal stenosis were prospectively compared as a case control study.

Objectives: This prospective case control study sought to evaluate bilateral microdecompressive laminatomy (MDL) for treatment of severe lumbar spinal stenosis.

Summary of Background Data: Total laminectomy is a general consensus on the therapy of severe spinal stenosis. The authors tried to investigate a new minimal invasive approach.

Methods: Patients were randomly divided into 2 groups. In first group, 34 patients underwent total laminectomy (TL) for severe lumbar spinal stenosis. In the second group, 37 patients with the same diagnosis underwent bilateral MDL. The groups were compared for disability, walking distance, degree of postoperative back and leg pain, perioperative complications, and postoperative instability. Radiographic analyses were performed at regular intervals to demonstrate satisfactory decompression.

Results: Mean follow-up was 5 years. Postoperative computerized tomography and magnetic resonance imaging demonstrated adequate decompressions in both groups. The walking distance, pain control, and disability scores were slightly higher among patients in the MDL group, although these results did not achieve statistical significance. Perioperative complications and postoperative instability were significantly higher in the TL group (P<0.05).

Conclusions: Compared with classic approaches, bilateral MDL provides adequate and safe decompression in lumbar spinal stenosis. It significantly reduces clinical symptoms and disability. However, TL shows higher perioperative complications and postoperative instability. To the best of our knowledge, this is the first study to define a bilateral MDL approach to treat the stenotic lumbar spine without a herniated disc.

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A Retrospective Analysis of Patient Perceived Outcomes in Patients 55 Years and Older Undergoing Anterior Cervical Discectomy and Fusion

J Spinal Disord Tech 2010;23:157–161

Study Design/Setting: Retrospective review of clinical outcomes after anterior cervical discectomy and fusion (ACDF) surgery with allograft and plating in patients over 55 years of age.

Objective: To evaluate the results of ACDF surgery in patients aged 55 years and older.

Summary of Background Data: ACDF surgery has been a standard treatment for cervical degenerative and herniated disc disease for many years. Previous assessments of efficacy have used patient perceived outcome measures including the Neck Disability Index (NDI) and the Short Form 36 Question Health Questionnaire (SF-36). Patient perceived outcome after ACDF surgery in an age specific cohort (55 y and older) has not been documented previously.

Methods: Fifty-two consecutive patients over 55 years of age who underwent 1 to 3 level ACDF with allograft and plating were identified. Patient perceived outcome questionnaires (NDI and SF-36) were available for 44 patients. There were 28 females and 16 males. Mean age at time of surgery was 61.8 years. Average length of follow-up was 25.2 months (12 to 54 mo).

Results: All but one patient demonstrated radiographic healing of the fusion site at the time of their last follow-up. The mean improvement of these 10 groups (total NDI score) was statistically significant (difference = 9.47, t=5.6390, P=1.5198E-06). There was a statistically significant decrease in disability in 7 of the 8 SF-36 categories as well. The mean of the 8 SF-36 categories (total SF-36) improved significantly (improvement=11.92, t= 3.6857, P=0.0007).

Conclusions: On the basis of our statistically significant improvement in NDI and SF-36 scores, as a measure of patient perceived outcome after ACDF surgery, outcomes after ACDF surgery in patients over 55 years of age are not significantly different than those of a younger patient population

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Study of the Anatomical Variations of Vertebral Artery in C2 Vertebra With Magnetic Resonance Imaging and Its Application in the C1–C2 Transarticular Screw Fixation

Spine 2010;35:1136–1143

Use of magnetic resonance imaging (MRI) with Constructive Interference in Steady State (CISS) sequence and isometric voxels to demonstrate the anatomic variations of vertebral artery in C2 vertebra. Objectives. To determine the transarticular screw trajectory on CISS MRI and to identify patients with anatomic variations of vertebral artery in C2 vertebra. Summary of Background Data. Atlantoaxial transarticular screw fixation has been reported to be biomechanically superior to other posterior techniques for atlantoaxial arthrodesis. Vertebral artery injury can be associated with catastrophic sequelae. Anatomic variation of vertebral artery is well recognized and computed tomography scan is the traditional preoperative assessment. However, no report has evaluated the use of MRI in preoperative assessment for the screw trajectories and the anatomic variation of vertebral artery. Methods. The 3-dimensional (3D) CISS MRI with isometric voxels was performed in 30 local Chinese patients. The 3D reconstruction images were created to determine the proposed screw trajectories and their relationship with the vertebral arteries. Results. In 12 patients (40%), the vertebral arteries were lying within the screw trajectories prohibiting transarticular screw fixation on at least one side. Bilateral variations with high risk of vertebral artery injuries were found in 6 patients. The remaining 6 patients had unilateral variations prohibiting the insertion of transarticular screws on one side. Conclusion. The 3D CISS MRI with isometric voxels is a safe and simple imaging technique to outline the vertebral arteries in C2. Reconstruction images are easily created and undistorted. It is one of the useful imaging in preoperative planning of transarticular screw fixation and determination of anatomy of vertebral artery.

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Short-term Progressive Spinal Deformity Following Laminoplasty Versus Laminectomy for Resection of Intradural Spinal Tumors: Analysis of 238 Patients

Neurosurgery 66:1005-1012, 2010 DOI: 10.1227/01.NEU.0000367721.73220.C9

Gross total resection of intradural spinal tumors can be achieved in the majority of cases with preservation of long-term neurological function. However, postoperative progressive spinal deformity complicates outcome in a subset of patients after surgery. We set out to determine whether the use of laminoplasty (LP) vs laminectomy (LM) has reduced the incidence of subsequent spinal deformity following intradural tumor resection at our institution.

METHODS:We retrospectively reviewed the records of 238 consecutive patients undergoing resection of intradural tumor at a single institution. The incidence of subsequent progressive kyphosis or scoliosis, perioperative morbidity, and neurological outcome were compared between the LP and LM cohorts.

RESULTS: One hundred eighty patients underwent LM and 58 underwent LP. Patients were 46 ± 19 years old with median modified McCormick score of 2. Tumors were intramedullary in 102 (43%) and extramedullary in 102 (43%). All baseline clinical, radiographic, and operative variables were similar between the LP and LM cohorts. LP was associated with a decreased mean length of hospitalization (5 vs 7 days; P = .002) and trend of decreased incisional cerebrospinal fluid leak (3% vs 9%; P = .14). Following LP vs LM, 5 (9%) vs 21 (12%) patients developed progressive deformity (P = .728) a mean of 14 months after surgery. The incidence of progressive deformity was also similar between LP vs LM in pediatric patients < 18 years of age (43% vs 36%), with preoperative scoliosis or loss of cervical/lumbar lordosis (28% vs 22%), or with intramedullary tumors (11% vs 11%).

CONCLUSION: LP for the resection of intradural spinal tumors was not associated with a decreased incidence of short-term progressive spinal deformity or improved neurological function. However, LP may be associated with a reduction in incisional cerebrospinal fluid leak. Longer-term follow-up is warranted to definitively assess the long-term effect of LP and the risk of deformity over time.

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Total Sagittal Spinal Alignment in Patients With Lumbar Canal Stenosis Accompanied by Intermittent Claudication

Spine 2010;35:E344–E346

Study Design. Cross-sectional study of total sagittal spinal alignment in lumbar spinal canal stenosis (LCS) patients with and without intermittent claudication.

Objective. To evaluate total sagittal spinal alignment in LCS. Summary of Background Data. The sagittal spinal alignment is an important factor in the management of lumbar degenerative diseases and lower back pain. Patients with LCS accompanied by intermittent claudication adopt a forward-bending posture during walking. However, few studies have quantitatively assessed the abnormal posture in LCS in relation to clinical symptoms.

Methods. This study analyzed 93 patients with LCS. They were divided into two groups according to the presence of neurogenic intermittent claudication; patients of the Claudicant group had intermittent claudication of the cauda equina (n  53; mean age, 66.7) and those of the Nerve root group had no claudication (n  40; mean age, 67.0). The following parameters were measured on the lateral whole-spine standing radiographs: the distance between the C7 plumb line and the posterior superior corner on the superior margin of S1 (sagittal vertical axis), the angle between the superior margin of the first lumbar vertebra and the first sacral vertebra (L1S1), lumbar lordotic angle, pelvic tilting angle (PA), and pelvic morphologic angle (PRS1).

Results. The sagittal vertical axis of the Claudicant group (57.6  37.5 mm) was significantly larger than that of the Nerve root group (40.3  42.3 mm) and was larger in both groups compared with the standard values. Lumbar lordotic angle was smaller (18.8°  13.2°) and pelvic tilting angle was larger (27.2°  8.3°) in patients with the Claudicant group than those with the Nerve root group (22.4°  14.0° and 22.7°  7.2°, respectively).

Conclusion. Patients of the Claudicant group exhibited forward bending of the trunk and pelvis backtilt, compared with those of the Nerve root group.


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Quality of Spinal Motion With Cervical Disk Arthroplasty. Computer-aided Radiographic Analysis

J Spinal Disord Tech 2010;23:89–95

Study Design: Kinematic study of a single site in an investigational device exemption trial.

Objective: Evaluate the center of rotation (COR) after Bryan cervical arthroplasty and compare adjacent segment motion after cervical disk arthroplasty and fusion using validated radiographic analysis.

Summary of Background Data: The goal of cervical arthroplasty is to reestablish spinal kinematics after anterior decompression. Excellent maintenance of range of motion has been reported for a variety of the prostheses; however, the manner the prostheses perform this task is different. A parameter that may be as important as range of motion is restoring the quality of motion. One of the important components is the COR that is easily studied biomechanically but has not been reported from in vivo studies. Furthermore, the effects on the quality of motion at adjacent levels have not been studied. The purpose of this study is to determine the quality of motion after Bryan cervical disk arthroplasty at the target level and the adjacent segments.

Methods: The first 48 patients diagnosed with single level cervical disk degenerative disease and associated myelopathy or radiculopathy from a single institution enrolled in the Bryan disk investigational device exemption trial were selected for inclusion. Twenty-two investigational patients and 26 anterior cervical discectomy and fusion controls were evaluated radiographically preoperatively and 3, 6, 12, and 24 months postoperatively. These results were analyzed using Quantitative Motion Analysis software manufactured by Medical Metrics Inc. Kinematic parameters included translation, sagittal rotation, anterior/posterior disk height, and the calculation of the COR both in the sagittal and coronal planes.

Results: At the arthroplasty level, the COR shifted more posterior (0.3 mm, 1% end plate width) and cephalad (4.9 mm, 20% end plate width) compared with the preoperative position, however, this change was not statistically significant (P=0.06). The variability of the COR, however, was less after arthroplasty compared with preoperative values. There was no significant difference in the short term between the adjacent levels after fusion compared with the prosthesis. At later time points (12 and 24 mo), however, the COR was significantly posterior at the level above arthroplasty compared with fusion (P<0.01). COR X was not significantly (P>0.3) different below fusions compared with arthroplasty. Sagittal rotation significantly increased at the level above for both the fusion and prosthesis groups. A trend was noted for increased translation (2.5% end plate width) at the level above a fusion compared with the Bryan disk at 24 months postoperatively, but this did not reach statistical significance.

Conclusions: Sagittal rotation increases above the level of the arthroplasty and fusion. In the long term, the arthroplasty group had a more posterior COR at the level above, compared with the level above a fusion. Translation at the level above a fusion was slightly increased but not statistically compared with the level above the arthroplasty with similar amounts of sagittal rotation (flexion/extension). Although not reaching statistical significance, the COR seemed to shift more posterior and cephalad at the arthroplasty level with less variability compared with the preoperative position.

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Early Rehabilitation Targeting Cognition, Behavior, and Motor Function After Lumbar Fusion A Randomized Controlled Trial

Spine 2010;35:848–857

Study Design. Open label randomized controlled trial with 3-, 6-, 12-month, and 2- to 3-year follow-up.

Objective. To investigate the effectiveness of a psychomotor therapy focusing on cognition, behavior, and motor relearning compared with exercise therapy applied during the first 3 months after lumbar fusion.

Summary of Background Data. Postoperative management after lumbar fusion commonly focuses on analgesic pain control and activities of daily living. After 3 months, exercise therapy is often implemented. No randomized controlled trial has investigated early rehabilitation techniques conducted during the first 3 months after surgery.

Methods. The study recruited 107 patients, aged 18 to 65 years, selected for lumbar fusion because of 12 months of symptomatic spinal stenosis, spondylosis, degenerative/isthmic spondylolisthesis, or degenerative disc disease. The exercise therapy group received a home program focusing on pain contingent training of back, abdominal, and leg muscle functional strength and endurance, stretching, and cardiovascular fitness. The psychomotor therapy group received a home program and 3 outpatient sessions focusing on modifying maladaptive pain cognitions, behaviors, and motor control. Rated questionnaires investigating functional disability, pain, health-related quality of life, functional self-efficacy, outcome expectancy, fear of movement/(re)injury, and coping were assessed at 3, 6, 12 months, and 2 to 3 years after surgery.

Results. Follow-up rates were 93% at 12 months and 81% at 2 to 3 years after surgery. Psychomotor therapy improved functional disability, self-efficacy, outcome expectancy, and fear of movement/(re)injury significantly more than exercise therapy at respective follow-up occasions. Similar results occurred for pain coping but group differences were nonsignificant at 2 to 3 years follow-up. Potentially clinical relevant higher reoperation rates occurred after psychomotor therapy but rates were within normal ranges.

Conclusion. The study shows that postoperative rehabilitation can be safely implemented during the first 3 months after lumbar fusion and should include measures to modify psychological as well as motor functions.

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An alternate method for placement of C-1 screws

J Neurosurg: Spine / Volume 12 / April 2010. DOI: 10.3171/2009.10.SPINE08541

Several techniques for the surgical stabilization of the atlas and the axis have been described. Placement of C-1 lateral mass screws is one of the latest technical advances, and has gained popularity due to its efficacy and biomechanical advantages. However, the technique for placement of C-1 lateral mass screws, as first described by Harms, can cause excessive bleeding or irritation of the C-2 nerve. An alternative technique is available for the placement of C-1 lateral mass screws that completely avoids the C-2 nerve/ganglion and its associated venous plexus. This new technique mitigates some of the risk associated with the Harms techniques and eliminates the need to use specialized screws (that is, smooth shanks).

Methods: Twenty-six patients underwent atlantoaxial or occipitocervical fusions incorporating the alternative technique of C-1 screw placement. Three surgeons at 3 different institutions performed the surgeries. Standard lateral fluoroscopy and fully threaded polyaxial screws were used in each case.

Results: Forty-nine screws were placed in C-1 lateral masses by using the new technique. Solid arthrodesis was achieved in all cases, with a mean follow-up period of 30 months. There were no cases of CSF leakage, new neurological deficit, injury to the C-2 ganglion, vertebral artery injury, or hardware failures.

Conclusions: The technique is a safe and effective way to fixate C-1 while avoiding the C-2 nerve/ganglion and venous plexus. The results indicate that excellent clinical and radiographic outcomes can be achieved with this new technique.

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Trends, Major Medical Complications, and Charges Associated With Surgery for Lumbar Spinal Stenosis in Older Adults

JAMA. 2010;303(13):1259-1265

In recent decades, the fastest growth in lumbar surgery occurred in older patients with spinal stenosis. Trials indicate that for selected patients, decompressive surgery offers an advantage over nonoperative treatment, but surgeons often recommend more invasive fusion procedures. Comorbidity is common in older patients, so benefits and risks must be carefully weighed in the choice of surgical procedure.

Objective: To examine trends in use of different types of stenosis operations and the association of complications and resource use with surgical complexity.

Design, Setting, and Patients: Retrospective cohort analysis of Medicare claims for 2002-2007, focusing on 2007 to assess complications and resource use in US hospitals. Operations for Medicare recipients undergoing surgery for lumbar stenosis (n=32 152 in the first 11 months of 2007) were grouped into 3 gradations of invasiveness: decompression alone, simple fusion (1 or 2 disk levels, single surgical approach), or complex fusion (more than 2 disk levels or combined anterior and posterior approach).

Main Outcome Measures: Rates of the 3 types of surgery, major complications, postoperative mortality, and resource use.

Results: Overall, surgical rates declined slightly from 2002-2007, but the rate of complex fusion procedures increased 15-fold, from 1.3 to 19.9 per 100.000 beneficiaries. Lifethreatening complications increased with increasing surgical invasiveness, from 2.3% among patients having decompression alone to 5.6% among those having complex fusions. After adjustment for age, comorbidity, previous spine surgery, and other features, the odds ratio (OR) of life-threatening complications for complex fusion compared with decompression alone was 2.95 (95% confidence interval [CI], 2.50-3.49). A similar pattern was observed for rehospitalization within 30 days, which occurred for 7.8% of patients undergoing decompression and 13.0% having a complex fusion (adjusted OR, 1.94; 95% CI, 1.74-2.17). Adjusted mean hospital charges for complex fusion procedures were US $80.888 compared with US $23.724 for decompression alone.

Conclusions: Among Medicare recipients, between 2002 and 2007, the frequency of complex fusion procedures for spinal stenosis increased while the frequency of decompression surgery and simple fusions decreased. In 2007, compared with decompression, simple fusion and complex fusion were associated with increased risk of major complications, 30-day mortality, and resource use.

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Effects of age on perioperative complications of extensive multilevel thoracolumbar spinal fusion surgery

J Neurosurg Spine 12:402–408, 2010. DOI: 10.3171/2009.10.SPINE08741

The elderly compose a substantial proportion of patients presenting with complex spinal pathology. Several recent studies have suggested that fusion of 4 or more levels increases the risk of perioperative complications in elderly patients. Therefore, the purpose of this study was to analyze the effects of age in persons undergoing multilevel (≥ 5 levels) thoracolumbar fusion surgery.

Methods. A retrospective review of all hospital records, operative reports, and clinic notes was conducted for 124 consecutive patients who underwent surgery between 2000 and 2007 with an average follow-up of 3.5 years and a minimum follow-up of 1.2 years. The most frequent preoperative diagnoses included scoliosis, tumor, osteomyelitis, vertebral fracture, and degenerative disc disease with stenosis. Complications were classified as intraoperative and major and minor postoperative as well as the need for revision surgery. Multivariate logistic regression analysis was used to determine the effects of age and other potentially prognostic factors.

Results. After controlling for other factors, increasing age was associated with an elevated risk for major postoperative complications (OR 1.04, 95% CI 1.00–1.10) as were increasing levels of fusion (OR 1.5, 95% CI 1.1–2.1) and male sex (OR 4.6, 95% CI 1.3–16.2). In patients 65 years of age or older, rates of intraoperative complications, major and minor postoperative complications, and reoperation were 14.1, 23.4, 29.7, and 26.6%, respectively. The number of comorbidities was associated with a greater risk for perioperative complications in elderly patients (OR 1.8, 95% CI 1.1–2.8).

Conclusions. Age is a positive risk factor for major postoperative complications in extensive thoracolumbar spinal fusion surgery. Complication rates in the elderly are high, and good clinical judgment and careful patient selection are needed before performing extensive thoracolumbar reconstruction in older persons.

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Overview of disc arthroplasty—past, present and future

DOI:10.1007/s00701-009-0529-5. Acta Neurochirugica

Degenerative disc disease is one of the most frequent spinal disorders. The anatomy and the biomechanics of the intervertebral disc are very complex, and the pathomechanics of its degeneration are poorly understood. Despite this complexity and uncertainty, great advances have been made in the field of disc replacement technology, with promising results. Difficulties are continuously being encountered, but careful analysis of the results and intensive research and development will assist in countering these problems. There are approximately 40 clinical reports in the literature describing various aspects of randomised controlled trials involving intervertebral disc arthroplasty. However, the majority of these publications do not provide reliable information, in that they give only interim results and/or the results from just one of the many centres in multicentre studies. Such publications must be interpreted with caution, since they do not always represent the results of the whole study population and may hence be underpowered. We identified six randomised controlled trials that compared the final clinical outcomes of disc arthroplasty and spinal fusion. The present systematic review attempts to give an overview of the current status of disc arthroplasty.

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Sagittal spinal alignment in patients with lumbar disc herniation

Eur Spine J (2010) 19:435–438. DOI 10.1007/s00586-009-1240-1

A retrospective cross-sectional study was designed to evaluate total sagittal spinal alignment in patients with lumbar disc herniation (LDH) and healthy subjects. Abnormal sagittal spinal alignment could cause persistent low back pain in lumbar disease. Previous studies analyzed sciatic scoliotic list in patients with lumbar disc herniation; but there is little or no information on the relationship between sagittal alignment and subjective findings.

The study subjects were 61 LDH patients and 60 age-matched healthy subjects. Preoperative and 6-month postoperatively lateral whole-spine standing radiographs were assessed for the distance between C7 plumb line and posterior superior corner on the top margin of S1 sagittal vertical axis (SVA), lumbar lordotic angle between the top margin of the first lumbar vertebra and first sacral vertebra (L1S1), pelvic tilting angle (PA), and pelvic morphologic angle (PRS1). Subjective symptoms were evaluated by the Japanese Orthopedic Association (JOA) score for lower back pain (nine points).

The mean SVA value of the LDH group (32.7 ± 46.5 mm, ± SD) was significantly larger than that of the control (2.5 ± 17.1 mm), while L1S1 was smaller (36.7 ± 14.5) and PA was larger (25.1 ± 9.0) in LDH than control group (49.0 ± 10.0 and 18.2 ± 6.0, respectively). At 6 months after surgery, the malalignment recovered to almost the same level as the control group.

SVA correlated with the subjective symptoms measured by the JOA score. Sagittal spinal alignment in LDH exhibits more anterior translation of the C7 plumb line, less lumbar lordosis, and a more vertical sacrum. Measurements of these spinal parameters allowed assessment of the pathophysiology of LDH.

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Accuracy of pedicle screw placement in the lumbosacral spine using conventional technique: CT postoperative assessment in 102 consecutive patients

Journal of Neurosurgery: Spine. March 2010.DOI: 10.3171/2009.9.SPINE09261

The goal of this study was to determine the incidence of screw misplacement and complications in a group of 102 patients who underwent transpedicle screw fixation in the lumbosacral spine with conventional open technique and intraoperative fluoroscopy. The results are compared with published data.

Methods: Cases involving 102 consecutive patients (424 inserted screws) were reviewed. Surgery was performed in all cases by the same surgeon’s team, using the same implant, and all results were assessed by means of a specific CT protocol. The screw position was assessed by the authors and an independent observer. Screw position was classified as correct when the screw was completely surrounded by the pedicle cortex, as “cortical encroachment” (questionable violation) if the pedicle cortex could not be visualized, and as “frank penetration” when the screw was outside the pedicular boundaries. Frank penetration was further subdivided as minor (when the edge of the screw thread was up to 2.0 mm outside the pedicle cortex), moderate (2.1–4 mm), and severe (> 4 mm). The incidence of intra- and postoperative complications not related to screw position as well as hardware failures were also registered, with a minimum follow-up duration of 8 months.

Results: The rate of frank pedicle screw misplacement was 5%. The rate of minimal or questionable pedicle wall violation was 2.8%. Among the frank misplacements, 6 were classified as minor, 12 as moderate, and 3 as severe penetration. Two patients (2%) had radicular pain and neurological deficits (inferomedial and inferolateral minor misplacement at L-4 and L-5, respectively), and 5 patients (4.9%) complained only of radicular pain. At the follow-up examination all patients had completely recovered their neurological function and radicular pain was resolved in all cases. The complications not related to screw malposition were 2 pedicle fractures (2% of patients), 1 nerve root injury (1%), and 1 dural laceration (1%). Five patients (4.8%) had postoperative anemia and required transfusions. Superficial or deep wound infection was noted in 3 patients (2.9%). Late hardware failure occurred in 2 patients (2%). One patient developed adjacent segmental instability and required additional surgery to extend the fusion.

Conclusions: Our rates of screw misplacement and complications compare favorably with the lowest rates of the series in which conventional technique was used and are close to the rates reported for image-guided methods. The risk of malpositioning may be reduced with careful preoperative surgical planning, accurate knowledge of the spinal anatomy, surgical experience, and correct indication for conventional surgery. The conventional technique still remains a practical, safe, and effective surgical method for lumbosacral fixation.

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Results After Lumbar Decompression With and Without Discectomy: Comparison of the Transspinous and Conventional Approaches

Neurosurgery 66[ONS Suppl 1]:ons152-ons160, 2010 DOI: : 10.1227/01.NEU.0000365826.15986.40

OBJECTIVE: To evaluate the efficacy of the transspinous approach compared with the conventional approach in single-level lumbar laminotomies with and without discectomies.
METHODS: Forty consecutive patients underwent single-level lumbar decompression with or without a discectomy. The first 20 patients underwent surgery by the conventional approach (11 with discectomy and 9 without), and the transspinous approach was used in the remaining 20 patients (11 with discectomy and 9 without). Results between the groups were assessed by comparing the following measures: length of inpatient hospital stay, postoperative pain and analgesia use, estimated blood loss, rate of postoperative disability and complications, and incision length.
RESULTS: The groups did not differ significantly with respect to age, level of pathology, insurance status, or type of analgesia used. The primary outcome was physical disability, measured using the Roland-Morris Disability Questionnaire. The secondary outcome was pain intensity, measured using the Brief Pain Inventory. Patients who underwent the transspinous approach had better outcomes across all measures with significance appreciated in those who underwent transspinous decompression with discectomies. Other statistically significant differences were identified in incision length and postoperative analgesia use at the end of 1 week. No statistically significant differences were identified in the rates of complications, estimated blood loss, inpatient narcotic analgesia use, or length of inpatient hospital stay.
CONCLUSION: Patients who underwent single-level lumbar decompression with or without discectomy had similar outcomes as those who underwent the conventional approach. Although of modest clinical significance, the transspinous approach may afford early mobilization and reduced postoperative pain while providing a satisfactory neurological and functional outcome.

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Overview of disc arthroplasty—past, present and future

Acta Neurochir (2010) 152:393–404. DOI 10.1007/s00701-009-0529-5

Degenerative disc disease is one of the most frequent spinal disorders. The anatomy and the biomechanics of the intervertebral disc are very complex, and the pathomechanics of its degeneration are poorly understood. Despite this complexity and uncertainty, great advances have been made in the field of disc replacement technology, with promising results. Difficulties are continuously being encountered, but careful analysis of the results and intensive research and development will assist in countering these problems. There are approximately 40 clinical reports in the literature describing various aspects of randomised controlled trials involving intervertebral disc arthroplasty. However, the majority of these publications do not provide reliable information, in that they give only interim results and/or the results from just one of the many centres in multicentre studies. Such publications must be interpreted with caution, since they do not always represent the results of the whole study population and may hence be underpowered. We identified six randomised controlled trials that compared the final clinical outcomes of disc arthroplasty and spinal fusion. The present systematic review attempts to give an overview of the current status of disc arthroplasty.

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Comparative fixation methods of cervical disc arthroplasty versus conventional methods of anterior cervical arthrodesis: serration, teeth, keels, or screws?

J Neurosurg Spine 12:214–220, 2010 (DOI: 10.3171/2009.9.SPINE08952)

Object. Using a synthetic vertebral model, the authors quantified the comparative fixation strengths and failure mechanisms of 6 cervical disc arthroplasty devices versus 2 conventional methods of cervical arthrodesis, highlighting biomechanical advantages of prosthetic endplate fixation properties.
Methods. Eight cervical implant configurations were evaluated in the current investigation: 1) PCM Low Profile; 2) PCM V-Teeth; 3) PCM Modular Flange; 4) PCM Fixed Flange; 5) Prestige LP; 6) Kineflex/C disc; 7) anterior cervical plate + interbody cage; and 8  ) tricortical iliac crest. All PCM treatments contained a serrated implant surface (0.4 mm). The PCM V-Teeth and Prestige contained 2 additional rows of teeth, which were 1 mm and 2 mm high, respectively. The PCM Modular and Fixed Flanged devices and anterior cervical plate were augmented with 4 vertebral screws. Eight pullout tests were performed for each of the 8 conditions by using a synthetic fixation model consisting of solid rigid polyurethane foam blocks. Biomechanical testing was conducted using an 858 Bionix test system configured with an unconstrained testing platform. Implants were positioned between testing blocks, using a compressive preload of −267 N. Tensile load-to-failure testing was performed at 2.5 mm/second, with quantification of peak load at failure (in Newtons), implant surface area (in square millimeters), and failure mechanisms.
Results. The mean loads at failure for the 8 implants were as follows: 257.4 ± 28.54 for the PCM Low Profile; 308.8 ± 15.31 for PCM V-Teeth; 496.36 ± 40.01 for PCM Modular Flange; 528.03± 127.8 for PCM Fixed Flange; 306.4 ± 31.3 for Prestige LP; 286.9 ± 18.4 for Kineflex/C disc; 635.53 ± 112.62 for anterior cervical plate + interbody cage; and 161.61 ± 16.58 for tricortical iliac crest. The anterior plate exhibited the highest load at failure compared with all other treatments (p < 0.05). The PCM Modular and Fixed Flange PCM constructs in which screw fixation was used exhibited higher pullout loads than all other treatments except the anterior plate (p < 0.05). The PCM VTeeth and Prestige and Kineflex/C implants exhibited higher pullout loads than the PCM Low Profile and tricortical iliac crest (p < 0.05). Tricortical iliac crest exhibited the lowest pullout strength, which was different from all other treatments (p < 0.05). The surface area of endplate contact, measuring 300 mm2 (PCM treatments), 275 mm2 (PrestigeLP), 250 mm2 (Kineflex/C disc), 180 mm2 (plate + cage), and 235 mm2 (tricortical iliac crest), did not correlate with pullout strength (p > 0.05). The PCM, Prestige, and Kineflex constructs, which did not use screw fixation, all failed by direct pullout. Screw fixation devices, including anterior plates, led to test block fracture, and tricortical iliac crest failed by direct pullout.
Conclusions. These results demonstrate a continuum of fixation strength based on prosthetic endplate design.Disc arthroplasty constructs implanted using vertebral body screw fixation exhibited the highest pullout strength. Prosthetic endplates containing toothed ridges (≥ 1 mm) or keels placed second in fixation strength, whereas endplates containing serrated edges exhibited the lowest fixation strength. All treatments exhibited greater fixation strength than conventional tricortical iliac crest. The current study offers insights into the benefits of various prosthetic endplate designs, which may potentially improve acute fixation following cervical disc arthroplasty.

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Effect of bupivacaine on intervertebral disc cell viability

The Spine Journal 10 (2010) 159–166

Bupivacaine is a local anesthetic commonly used to relieve or control pain in interventional spine procedures. Bupivacaine has been shown to be toxic to articular cartilage, which has similarities to intervertebral disc (IVD) cartilage, raising concern over a potentially negative effect of bupivacaine on the disc.

PURPOSE: To determine bupivacaine’s effect on cell viability of IVD cells in vitro and to elucidate whether this is through apoptosis or necrosis.

STUDY DESIGN: In vitro controlled study of bupivacaine effect on cell viability in human and rabbit IVD cells.

SUBJECTS: Rabbit annulus fibrosus (AF) tissue, nucleus pulposus (NP) cells, and knee articular chondrocytes were isolated from New Zealand white rabbits. Human AF and NP cells were isolated from stage 3 to 4 degenerative disc surgical specimens.

OUTCOME MEASURES: Cell viability was assessed after exposure to bupivacaine via trypan blue staining or flow cytometry.

METHODS: Annulus fibrosus and NP cells were grown in monolayer and alginate beads, respectively, to simulate their physiologic environment. The cells were then exposed to bupivacaine or saline control at 60 and 120 minutes and examined for cell viability. RESULTS: Rabbit NP cell death demonstrated a time and dose dependence in response to bupivacaine. In addition, cell death was greater than that observed for articular chondrocytes. Rabbit AF tissue also demonstrated increased cell death in response to bupivacaine exposure. Human NP cells demonstrated time-dependent cell death, with greater necrosis than apoptosis. Annulus fibrosus cells grown in monolayers also resulted in similar effects, with greater necrosis rather than apoptosis.

CONCLUSIONS: Despite its pain relieving properties, bupivacaine decreases cell viability in rabbit and human disc cells in a time-dependent manner. In addition, the changes observed are greater than that seen for articular chondrocytes. This increase in cell death appears to be related to an increase in necrosis rather than apoptosis. Whether bupivacaine exerts similar effects in vivo or how this relates to overall clinical outcome remains to be explored.

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Long-term back pain after a single-level discectomy for radiculopathy: incidence and health care cost analysis

J Neurosurg Spine 12:178–182, 2010.(DOI: 10.3171/2009.9.SPINE09410)

Object. The most common spinal procedure performed in the US is lumbar discectomy for disc herniation. Long- term disc degeneration and height loss occur in many patients after lumbar discectomy. The incidence of mechanical back pain following discectomy varies widely in the literature, and its associated health care costs are unknown. The authors set out to determine the incidence of and the health care costs associated with mechanical back pain attributed to segmental degeneration or instability at the level of a prior discectomy performed at their institution.

Methods. The authors retrospectively reviewed the data for 111 patients who underwent primary, single-level lumbar hemilaminotomy and discectomy for radiculopathy. All diagnostic modalities, conservative therapies, and operative treatments used for the management of postdiscectomy back pain were recorded. Institutional billing and accounting records were reviewed to determine the billed costs of all diagnostic and therapeutic measures.

Results. At a mean follow-up of 37.3 months after primary discectomy, 75 patients (68%) experienced minimal to no back pain, 26 (23%) had moderate back pain requiring conservative treatment only, and 10 (9%) suffered severe back pain that required a subsequent fusion surgery at the site of the primary discectomy. The mean cost per patient for conservative treatment alone was $4696. The mean cost per patient for operative treatment was $42,554. The esti- mated cost of treatment for mechanical back pain associated with postoperative same-level degeneration or instability was $493,383 per 100 cases of first-time, single-level lumbar discectomy ($4934 per primary discectomy).

Conclusions. Postoperative mechanical back pain associated with same-level degeneration is not uncommon in patients undergoing single-level lumbar discectomy and is associated with substantial health care costs.

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Economic impact of improving outcomes of lumbar discectomy

The Spine Journal 10 (2010) 108–116.doi:10.1016/j.spinee.2009.08.453

BACKGROUND: Lumbar discectomy is usually a successful operation with a relatively low cost. Potential adjunctive procedures, such as repairing the anulus fibrosus or nucleus replacements, necessitate a cost-benefit analysis.

PURPOSE: This economic analysis was performed to understand the potential value of advanced implantable technologies designed to improve outcomes after discectomy.

STUDY DESIGN/SETTING: Using an insurance claims–based database, the economics of lessthan- favorable outcomes after lumbar discectomy were studied. Estimates of improved clinical outcomes because of adjunctive surgical procedural items were modeled.

PATIENT SAMPLE: Using Current Procedural Terminology (CPT-4) codes and International Classification of Diseases, Clinical Modification procedure codes (ICD-9 CM), all lumbar discectomy patients were identified in a 6-month period from a large, 2002, commercially available claims-based data set representing 3.1 million insured lives.

OUTCOME MEASURES: Not applicable.

METHODS: Longitudinal data analysis from 3 years (2002–2004) of the database was performed for evidence of claims after the insured’s discectomy (up to 18 months post) as a utilization estimate of surgical and medical treatment resultant of less-than-favorable outcomes. Incidence and cost of secondary operations, medical management, and complications were determined. Using these inputs, an economic model was generated to estimate the effect of improvement in discectomy outcomes.

RESULTS: Of the 494 patients who had a discectomy within a 6-month period, 137 (28%) had subsequent claims that suggested the outcome was less than favorable within 18 months. Patients whose insurance claims included codes for a second operation (n552 patients with 56 operations; 11%) and patients being medically/nonsurgically managed (n585, 17%) were studied. Average reimbursed charges incurred (2006 dollars) of repeated discectomy (80% of cases) was $6,907 and for arthrodesis (20% of cases) was $24,375. Average additional medical treatment cost to diagnose or manage poor outcome requiring another surgery was $3,365. Procedure-related complications within 40 days of surgery were evident in 15% of the group; with additional average cost to manage of $3,939.

CONCLUSIONS: Substantial cost associated with poor discectomy outcomes is often overlooked or underappreciated. Surgical technologies that can improve outcomes of discectomy by 50% to 70% thus improving patient quality of life can be overall cost-neutral between $971 and $1,655 additionally per patient.

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