Use of a Reverse Bohlman Technique for Low-Grade Spondylolisthesis

Background

Treatment of spondylolisthesis can be difficult with regard to patients with high sacral slopes that may prohibit placement of interbody grafts for fusions across that segment. Here, we describe placement of a reverse Bohlman technique from an anterior approach to obtain fusion across a low-grade spondylolisthesis with a high sacral slope to obtain anterior fusion.

Methods

A chart review was conducted on this single patient regarding his clinical course and outcome.

Results

A 54-year-old male presented with low-back pain associated with bilateral leg pain dating back several years. Plain films demonstrated a Grade II isthmic spondylolisthesis at L5-S1 with spinopelvic measurements of 73° sacral slope, 82° lumbar lordosis, 12° pelvic tilt, and 94° pelvic incidence. Magnetic resonance imaging showed bilateral L5 pars defects with diffuse degenerative disease from L4 through S1 and significant ligamentous and facet hypertrophy. He underwent an L4-5 anterior lumbar interbody fusion and an L5-S1 reverse Bohlman placement of a transvertebral transsacral titanium mesh cage. This was supplemented with a posterior decompression and instrumentation from L4-ilium. He had resolution of his radiculopathy and has maintained a good clinical outcome at 3 years follow up.

Conclusions

We present here a patient with low-grade spondylolisthesis and a steep sacral slope who underwent a successful reverse Bohlman approach with long-term follow up. This report highlights the potential utility of this method as a viable alternative for patients with low-grade spondylolisthesis.

Level of Evidence

IV.

Clinical Relevance

Technical description of surgical technique.

Complications associated with intrathecal morphine in spine surgery: a retrospective study

Background

Supplemental intrathecal morphine (ITM) represents an option to manage postoperative pain after spine surgery due to ease of administration and ability to confer effective short-term analgesia at low dosages. However, whether ITM increases risk of surgical site infections (SSI), cerebrospinal fluid (CSF) leak, and incidental dural tears (IDT) has not been investigated. Therefore, this study was performed to determine the rates of SSI, CSF leak, and IDT in patients that received ITM.

Methods

Patients that underwent posterior instrumented fusion from January 2010 to 2016 that received ITM were compared to controls with respect to demographic, medical, surgical, and outcome data. Fisher's exact test was used to compare rates of SSI, CSF leak, and IDT between groups. Poisson regression was used to analyze complication rates after adjusting for the influence of covariates and potential confounders.

Results

A total of 512 records were analyzed. ITM was administered to 78 patients prior to wound closure. The remaining 434 patients compromised the control group. IDT was significantly more common among patients receiving ITM (P=0.009). Differences in rates of CSF leak and SSI were not statistically significant (P=0.373 and P=0.564, respectively). After compensating for additional variables, Poisson regression revealed a significant increase in rates of IDT (P=0.007) according to ITM injection and advanced age (P=0.014). There was no significant difference in rates of CSF leak or SSI after accounting for the additional variables (P>0.05).

Conclusions

ITM for pain control in posterior instrumented spinal fusion surgery was linked to increased likelihood of IDT but not CSF leaks or SSI. Age was also noted to be a significant predictor of IDT. Spine surgeons should weigh potential risks against benefits when deciding whether to administer ITM for postoperative pain management following spine surgery.

An in Vitro Biomechanical Model of Differing Pedicle Screw Configurations for Long Construct Segmental Thoracic Fixation

BACKGROUND

The optimum pattern of pedicle screw (PS) fixation during long-segment thoracic fixation has not been determined.

OBJECTIVE

To evaluate rod stress and construct stability with minimal, alternating, skipped, and bilateral PS constructs in the iatrogenically destabilized thoracic spine.

METHODS

Eight cadaveric thoracic specimens (T3-T12) were initially tested intact to ±5 Nm using a custom 6 degree-of-freedom spine testing apparatus in flexion-extension (FE), lateral bending (LB), and axial rotation. Specimens were instrumented with T4-T10 bilateral PS, with Ponte osteotomies to introduce instability. Rods were bent to fit the PS and then spines were tested with the minimal, alternating, skipped, and bilateral fixation patterns. Range of motion (ROM) was calculated from T4-T10 and segmentally. In addition, strain gauges fixed to the spinal rods measured rod stress under FE and LB. Results were compared using ANOVA and post hoc Holm Sidak tests.

RESULTS

All fixation patterns provided significant reductions in ROM with respect to the intact spine. In all motion planes, minimal provided the least amount of rigidity, while bilateral provide the greatest; however, no statistically significant differences were detected in FE. In LB and axial rotation, skipped, alternating, and bilateral were all significantly more rigid than minimal (P < .01). Rod strains were greatest under LB and correlated with overall construct ROM, where bilateral had significantly lower strain than the other patterns (P < .05).

CONCLUSION

All constructs effectively decreased thoracic ROM. There was significant improvement in stabilization and decreased rod stress when more fixation points beyond the minimal construct were included.

A Novel Lumbar Motion Segment Classification to Predict Changes in Segmental Sagittal Alignment After Lateral Interbody Fixation

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

Lateral interbody fixation is being increasingly used for the correction of segmental sagittal parameters. One factor that affects postoperative correction is the resistance afforded by posterior hypertrophic facet joints in the degenerative lumbar spine. In this article, we describe a novel preoperative motion segment classification system to predict postoperative correction of segmental sagittal alignment after lateral lumbar interbody fusion.

METHODS

Preoperative computed tomography scans were analyzed for segmental facet osseous anatomy for all patients undergoing lateral lumbar interbody fusion at 3 institutions. Each facet was assigned a facet grade (min = 0, max = 2), and the sum of the bilateral facet grades was the final motion segment grade (MSG; min = 0, max = 4). Preoperative and postoperative segmental lordosis was measured on standing lateral radiographs. Postoperative segmental lordosis was also conveyed as a percentage of the implanted graft lordosis (%GL). Simple linear regression was conducted to predict the postoperative segmental %GL according to MSG.

RESULTS

A total of 36 patients with 59 operated levels were identified. There were 19 levels with MSG 0, 14 levels with MSG 1, 13 levels with MSG 2, 8 levels with MSG 3, and 5 levels with MSG 4. Mean %GL was 115%, 90%, 77%, 43%, and 5% for MSG 0 to 4, respectively. MSG significantly predicted postoperative %GL (P < .01). Each increase in MSG was associated with a 28% decrease in %GL.

CONCLUSIONS

We propose a novel facet-based motion segment classification system that significantly predicted postoperative segmental lordosis after lateral lumbar interbody fusion.

Biomechanical analysis of lateral interbody fusion strategies for adjacent segment degeneration in the lumbar spine

BACKGROUND CONTEXT

Surgical treatment of symptomatic adjacent segment disease (ASD) typically involves extension of previous instrumentation to include the newly affected level(s). Disruption of the incision site can present challenges and increases the risk of complication. Lateral-based interbody fusion techniques may provide a viable surgical alternative that avoids these risks. This study is the first to analyze the biomechanical effect of adding a lateral-based construct to an existing fusion.

PURPOSE

The study aimed to determine whether a minimally invasive lateral interbody device, with and without supplemental instrumentation, can effectively stabilize the rostral segment adjacent to a two-level fusion when compared with a traditional posterior revision approach.

STUDY DESIGN/SETTING

This is a cadaveric biomechanical study of lateral-based interbody strategies as add-on techniques to an existing fusion for the treatment of ASD.

METHODS

Twelve lumbosacral specimens were non-destructively loaded in flexion, extension, lateral bending, and torsion. Sequentially, the tested conditions were intact, two-level transforaminal lumbar interbody fusion (TLIF) (L3-L5), followed by lateral lumbar interbody fusion procedures at L2-L3 including interbody alone, a supplemental lateral plate, a supplemental spinous process plate, and then either cortical screw or pedicle screw fixation. A three-level TLIF was the final instrumented condition. In all conditions, three-dimensional kinematics were tracked and range of motion (ROM) was calculated for comparisons. Institutional funds (<$50,000) in support of this work were provided by Medtronic Spine.

RESULTS

The addition of a lateral interbody device superadjacent to a two-level fusion significantly reduced motion in flexion, extension, and lateral bending (p<.05). Supplementing with a lateral plate further reduced ROM during lateral bending and torsion, whereas a spinous process plate further reduced ROM during flexion and extension. The addition of posterior cortical screws provided the most stable lateral lumbar interbody fusion construct, demonstrating ROM comparable with a traditional three-level TLIF.

CONCLUSIONS

The data presented suggest that a lateral-based interbody fusion supplemented with additional minimally invasive instrumentation may provide comparable stability with a traditional posterior revision approach without removal of the existing two-level rod in an ASD revision scenario.

Bow Hunter's Syndrome: Surgical Management (Video) and Review of the Literature

BACKGROUND

Bow Hunter's syndrome (BHS) is a rare condition characterized by vertebrobasilar insufficiency associated with rotational vertebral artery occlusion during head movement. Many existing reports describe surgical management, although no single technique has proven superior.

OBJECTIVE

To review all reported cases of BHS with focus on outcomes of individual techniques as well as to present a video report of a posterior decompression without fusion performed at the authors' institution.

METHODS

We searched PubMed for all relevant articles of BHS available in the English language. Pertinent studies were further characterized into surgical technique performed and associated outcomes.

RESULTS

We included 27 studies in our review, excluding the case presented, for a total of 65 cases of BHS. These cases discuss anterior versus posterior decompressions, the need for fusion, coil embolization techniques, the efficacy of intraoperative dynamic angiography, and success rate with symptom resolution being the primary endpoint. A total of 53 cases underwent decompression without fusion, with an overall success rate of 90.6% (n = 48/53). Similarly, eleven cases underwent decompression with fusion, with a success rate of 91% (n = 10/11). Two additional cases opted for coil embolization, one of which reported resolution of symptoms. Furthermore, we present a video case of a posterior decompression without fusion with resolution of symptoms.

CONCLUSIONS

BHS remains a rare clinical condition with no clear superior method of treatment. Rates of symptom resolution are similar among cases undergoing decompression with or without fusion. Coil embolization has been reported with limited success in 2 cases.

A Portable Shoulder-Mounted Camera System for Surgical Education in Spine Surgery

The past several years have demonstrated an increased recognition of operative videos as an important adjunct for resident education. Currently lacking, however, are effective methods to record video for the purposes of illustrating the techniques of minimally invasive (MIS) and complex spine surgery. We describe here our experiences developing and using a shoulder-mounted camera system for recording surgical video. Our requirements for an effective camera system included wireless portability to allow for movement around the operating room, camera mount location for comfort and loupes/headlight usage, battery life for long operative days, and sterile control of on/off recording. With this in mind, we created a shoulder-mounted camera system utilizing a GoPro™ HERO3+, its Smart Remote (GoPro, Inc., San Mateo, California), a high-capacity external battery pack, and a commercially available shoulder-mount harness. This shoulder-mounted system was more comfortable to wear for long periods of time in comparison to existing head-mounted and loupe-mounted systems. Without requiring any wired connections, the surgeon was free to move around the room as needed. Over the past several years, we have recorded numerous MIS and complex spine surgeries for the purposes of surgical video creation for resident education. Surgical videos serve as a platform to distribute important operative nuances in rich multimedia. Effective and practical camera system setups are needed to encourage the continued creation of videos to illustrate the surgical maneuvers in minimally invasive and complex spinal surgery. We describe here a novel portable shoulder-mounted camera system setup specifically designed to be worn and used for long periods of time in the operating room.

Semitendinosus Graft for Interspinous Ligament Reinforcement in Adult Spinal Deformity

Proximal junctional kyphosis is an increasingly recognized complication following long-segment posterior spinal fusion for adult spinal deformity. The authors describe a novel technique for interspinous ligament reinforcement at the proximal adjacent levels using a cadaveric semitendinosus tendon graft secured with an Ethibond No. 2 double filament (Ethicon, Somerville, New Jersey) via the Krackow suture weave. A retrospective review identified 4 patients who had received this graft. No proximal junctional kyphosis was seen at a mean short-term follow-up of 5.5 months. Interspinous ligament reinforcement at the proximal adjacent level with a cadaveric semitendinosus tendon graft is a feasible strategy for preventing proximal junctional kyphosis. [Orthopedics. 2017; 40(1):e206-e210.].

Complications associated with the Dynesys dynamic stabilization system: a comprehensive review of the literature

The Dynesys dynamic stabilization system is an alternative to rigid instrumentation and fusion for the treatment of lumbar degenerative disease. Although many outcomes studies have shown good results, currently lacking is a comprehensive report on complications associated with this system, especially in terms of how it compares with reported complication rates of fusion. For the present study, the authors reviewed the literature to find all studies involving the Dynesys dynamic stabilization system that reported complications or adverse events. Twenty-one studies were included for a total of 1166 patients with a mean age of 55.5 years (range 39-71 years) and a mean follow-up period of 33.7 months (range 12.0-81.6 months). Analysis of these studies demonstrated a surgical-site infection rate of 4.3%, pedicle screw loosening rate of 11.7%, pedicle screw fracture rate of 1.6%, and adjacent-segment disease (ASD) rate of 7.0%. Of studies reporting revision surgeries, 11.3% of patients underwent a reoperation. Of patients who developed ASD, 40.6% underwent a reoperation for treatment. The Dynesys dynamic stabilization system appears to have a fairly similar complication-rate profile compared with published literature on lumbar fusion, and is associated with a slightly lower incidence of ASD.

Assessment of outcome following the use of recombinant human bone morphogenetic protein-2 for spinal fusion in the elderly population

INTRODUCTION

Although the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) for spinal fusion has been fairly studied in the general population, relatively little research has been conducted on its use in the elderly patient demographic despite this population's growth. The authors sought to examine the clinical efficacy, complication rate, and cost-effectiveness of rhBMP-2 use in elderly patients undergoing spinal fusion surgery.

EVIDENCE ACQUISITION

We conducted a systematic review of the published literature for elderly patients that underwent spinal fusion surgery with the use of rhBMP-2. A systematic search was performed utilizing the PUBMED and MEDLINE databases in order to identify all papers dealing with recombinant human Bone Morphogenic Protein-2 use in patients over the age of 60 years.

EVIDENCE SYNTHESIS

Twenty-five papers were identified that met our inclusion criteria. While successful fusion, improvement in pain, and improved quality of life were encountered in elderly patients who were treated with fusions surgery along with rhBMP-2, there were several complications that were encountered including seroma formation, pleural effusions, and bone non-union.

CONCLUSIONS

The literature demonstrated that BMP serves as a potent osteoinductive agent in the elderly with similar efficacy to bone autograft. Although use of BMP showed mixed results and had higher initial costs, when taken into account with complication correction and costs, BMP usage appears to be more economically beneficial overall. Future studies are needed to clarify the clinical significance of the complications encountered in elderly patients treated with rhBMP-2. Future research can assist in developing recommendations which can minimize these risks in the elderly patient demographic.

Biomechanical Analysis of the Proximal Adjacent Segment after Multilevel Instrumentation of the Thoracic Spine: Do Hooks Ease the Transition?

Study Design Biomechanical cadaveric study. Objective Clinical studies indicate that using less-rigid fixation techniques in place of the standard all-pedicle screw construct when correcting for scoliosis may reduce the incidence of proximal junctional kyphosis and improve patient outcomes. The purpose of this study is to investigate whether there is a biomechanical advantage to using supralaminar hooks in place of pedicle screws at the upper-instrumented vertebrae in a multilevel thoracic construct. Methods T7-T12 spines were biomechanically tested: (1) intact; (2) following a two-level pedicles screw fusion from T9 to T11; and after proximal extension of the fusion to T8-T9 with (3) bilateral supra-laminar hooks, (4) a unilateral hook + unilateral screw hybrid, or (5) bilateral pedicle screws. Specimens were nondestructively loaded while three-dimensional kinematics and intradiscal pressure at the supra-adjacent level were recorded. Results Supra-adjacent hypermobility was reduced when bilateral hooks were used in place of pedicle screws at the upper-instrumented level, with statistically significant differences in lateral bending and torsion (p < 0.05 and p < 0.001, respectively). Disk pressures in the supra-adjacent segment were not statistically different among top-off techniques. Conclusions The use of supralaminar hooks at the top of a multilevel posterior fusion construct reduces the stress at the proximal uninstrumented motion segment. Although further data is needed to provide a definitive link to the clinical occurrence of PJK, this in vitro study demonstrates the potential benefit of "easing" the transition between the stiff instrumented spine and the flexible native spine and is the first to demonstrate these results with laminar hooks.

Large solitary osteochondroma of the thoracic spine: Case report and review of the literature

Background:

Spinal osteochondromas are typically benign tumors, but patients may present with myelopathy and neurologic deficits if there is tumor encroachment within the spinal canal.

Case Description:

We report here a case of a large solitary osteochondroma originating from the posterior vertebral body of T9 causing spinal cord compression and myelopathy. A 17-year-old man presented with 3 months of bilateral feet numbness and gait difficulty. Imaging demonstrated a large left-sided 5.9 cm × 5.0 cm × 5.4 cm osseous mass arising from the T9 vertebra consistent with an osteochondroma. He underwent bilateral costotransversectomies, and a left two-level lateral extracavitary approach for three partial corpectomies to both safely decompress the spinal canal as well as obtain a gross total resection of the tumor. Use of the O-arm intraoperative stereotactic computed tomographic navigation system assisted in delineating the osseous portions of the tumor for surgical removal. He experienced complete neurologic recovery after operative intervention.

Conclusion:

Careful surgical planning is needed to determine the best approach for spinal cord decompression and resection of this tumor, especially taking into account the bony elements from which it arises. We present this case, to highlight the feasibility of a single-stage posterior approach to the ventral thoracic spine for the resection of a large solitary thoracic osteochondroma causing cord compression.

Emergency room resource utilization by patients with low-back pain

OBJECTIVE

The objective of this study was to determine factors associated with admission to the hospital through the emergency room (ER) for patients with a primary diagnosis of low-back pain (LBP). The authors further evaluated the impact of ER admission and patient characteristics on mortality, discharge disposition, and hospital length of stay.

METHODS

The authors conducted a retrospective analysis of patients with LBP discharged from hospitals according to the Nationwide Inpatient Sample (NIS) between 1998 and 2007. Univariate comparisons of patient characteristics according to the type of admission (ER versus non-ER) were conducted. Multivariate analysis evaluated factors associated with an ER admission, risk of mortality, and nonroutine discharge.

RESULTS

According to the NIS, approximately 183,151 patients with a primary diagnosis of LBP were discharged from US hospitals between 1998 and 2007. During this period, an average of 65% of these patients were admitted through the ER, with a significant increase from 1998 (54%) to 2005 (71%). Multivariate analysis revealed that uninsured patients (OR 2.1, 95% CI 1.7–2.6, p < 0.0001) and African American patients (OR 1.5, 95% CI 1.2–1.7, p < 0.0001) were significantly more likely to be admitted through the ER than private insurance patients or Caucasian patients, respectively. Additionally, a moderate but statistically significant increase in the likelihood of ER admission was noted for patients with more preexisting comorbidities (OR 1.1, 95% CI 1.0–1.2, p < 0.001). An 11% incremental increase in the odds of admission through the ER was observed with each year increment (OR 1.1, 95% CI 1.0–1.2, p < 0.001). Highest income patients ($45,000+) were more likely to be admitted through the ER (OR 1.3, 95% CI 1.1–1.6, p = 0.007) than the lowest income cohort. While ER admission did not impact the risk of mortality (OR 0.95, 95% CI 0.60–1.51, p = 0.84), it increased the odds of a nonroutine discharge (OR 1.39, 95% CI 1.26–1.53, p < 0.0001).

CONCLUSIONS

A significant majority of patients discharged from hospitals in the US from 1998 to 2007 with a primary diagnosis of LBP were admitted through the ER, with more patients being admitted via this route each year. These patients were less likely to be discharged directly home compared with patients with LBP who were not admitted through the ER. Uninsured and African American patients with LBP were more likely to be admitted through the ER than their counterparts, as were patients with more preexisting health problems. Interestingly, patients with LBP at the highest income levels were more likely to be admitted through hospital ERs. The findings suggest that socioeconomic factors may play a role in the utilization of ER resources by patients with LBP, which in turn appears to impact at least the short-term outcome of these patients.

Stem cells and spinal fusion--are we there yet?

Wheeler DL, Fredericks DC, Dryer RF, Bae HW. Allogeneic mesenchymal precursor cells (MPCs) combined with an osteoconductive scaffold to promote lumbar interbody spine fusion in an ovine model. Spine J 2016:16:389-99 (in this issue).

Effects of fusion and conservative treatment on disc degeneration and rates of subsequent surgery after thoracolumbar fracture

OBJECT

The objective of this study was to compare the incidence of degeneration and need for subsequent fusion surgery between patients who were treated nonsurgically and patients treated with fusion after a diagnosis of thoracic-or lumbar-level fracture without degenerative disease.

METHODS

The authors performed a retrospective study of Orthopedic United Healthcare patients diagnosed with thoracic or lumbar fracture. Patients were filtered into thoracic and lumbar fracture groups using diagnostic codes and then assigned to one of 2 treatment subgroups (fusion surgery or no surgery) on the basis of procedural codes. Disc degeneration and follow-up surgery were recorded. Chi-square statistical analysis was used.

RESULTS

Of 3699 patients diagnosed with a thoracic fracture, 117 (3.2%) underwent thoracic fusion and 3215 (86.9%) were treated nonsurgically. Within 3 years, 147 (4.6%) patients from the nonsurgical subgroup and fewer than 11 (0.9%-8.5%) from the fusion subgroup were diagnosed with thoracic disc degeneration. From the nonsurgical subgroup, 11 (0.3%) patients underwent a thoracic surgery related to disc degeneration compared with zero from the fusion group (p > 0.05). Of 5016 patients diagnosed with lumbar fracture, 150 (3.0%) underwent fusion and 4371 (87.1%) had no surgery. Within 3 years, 503 patients (11.5%) from the nonsurgical subgroup and 35 (23.3%) from the fusion subgroup were diagnosed with lumbar disc degeneration (p < 0.05). From the nonsurgical subgroup, 42 (1.0%) went on to have surgery related to disc degeneration, compared with fewer than 11 (0.7%-6.7%) from the fusion subgroup (values not precise due to privacy limitations).

CONCLUSIONS

Fusion surgery for thoracic fracture does not appear to increase the likelihood of undergoing future surgery. In the lumbar region, initial fusion surgery appears to increase the incidence of disc degeneration and could potentially necessitate future surgeries.

Novel application of pre-operative vertebral body embolization to reduce intraoperative blood loss during a three-column spinal osteotomy for non-oncologic spinal deformity

Three column osteotomies (3CO) of the lumbar spine are powerful corrective procedures used in the treatment of kyphoscoliosis. Their efficacy comes at the cost of high reported complication rates, notably significant estimated blood loss (EBL). Previously reported techniques to reduce EBL have had modest efficacy. Here we describe a potential technique to decrease EBL during pedicle subtraction osteotomy (PSO) of the lumbar spine by means of pre-operative vertebral body embolization - a technique traditionally used to reduce blood loss prior to spinal column tumor resection. We present a 62-year-old man with iatrogenic kyphoscoliosis who underwent staged deformity correction. Stage 1 involved thoracolumbar instrumentation followed by transarterial embolization of the L4 vertebral body through bilateral segmental arteries. A combination of polyvinyl alcohol particles and Gelfoam (Pfizer, New York, NY, USA) were used. Following embolization there was decreased angiographic blood flow to the small vessels of the L4 vertebral body, while the segmental arteries remained patent. Stage 2 consisted of an L4 PSO and fusion. The EBL during the PSO procedure was 1L, which compared favorably to that during previous PSO at this institution as well as to quantities reported in previous literature. There have been no short term (5 month follow-up) complications attributable to the vertebral body embolization or surgical procedure. Although further investigation into this technique is required to better characterize its safety and efficacy in reducing EBL during 3CO, we believe this patient illustrates the potential utility of pre-operative vertebral embolization in the setting of non-oncologic deformity correction surgery.

Supra-psoas shallow docking in lateral interbody fusion

BACKGROUND

Lateral interbody fusion techniques have been linked with considerable postoperative morbidity, often the outcome of direct psoas trauma. The most common neurological postoperative complications are transient motor weakness/palsy and sensory dysesthesia, which can be permanent. It appears that these neural complications are a result of passing through the psoas muscle where the potential for nerve injury is significant. The supra-psoas shallow docking method may be a safer alternative and may help minimize morbidities by eliminating or reducing direct psoas injury.

OBJECTIVE

To describe the operative technique of performing lateral interbody fusion using supra-psoas retractor docking.

METHODS

The authors describe the surgical technique including side selection, positioning, and patient outcomes.

RESULTS

Fifteen patients were treated with the supra-psoas shallow docking method. Specifically, no patient reported weakness, numbness, and/or pain on the side that underwent the surgery. In these cases, performing lateral transpsoas interbody fusion using supra-psoas shallow docking appeared to minimize the most common neurological postoperative complications of the surgery, motor weakness/palsy and sensory dysesthesia, which may be a result of dilation of the psoas muscle.

CONCLUSION

The shallow docking technique may decrease postoperative morbidities by docking on top of psoas muscle instead of passing through it. An important potential benefit of this approach is direct visualization of the lumbosacral plexus, which may potentially minimize the postoperative neurological morbidity often encountered in patients after this surgery.

Cervical spine alignment, sagittal deformity, and clinical implications: a review

This paper is a narrative review of normal cervical alignment, methods for quantifying alignment, and how alignment is associated with cervical deformity, myelopathy, and adjacent-segment disease (ASD), with discussions of health-related quality of life (HRQOL). Popular methods currently used to quantify cervical alignment are discussed including cervical lordosis, sagittal vertical axis, and horizontal gaze with the chin-brow to vertical angle. Cervical deformity is examined in detail as deformities localized to the cervical spine affect, and are affected by, other parameters of the spine in preserving global sagittal alignment. An evolving trend is defining cervical sagittal alignment. Evidence from a few recent studies suggests correlations between radiographic parameters in the cervical spine and HRQOL. Analysis of the cervical regional alignment with respect to overall spinal pelvic alignment is critical. The article details mechanisms by which cervical kyphotic deformity potentially leads to ASD and discusses previous studies that suggest how postoperative sagittal malalignment may promote ASD. Further clinical studies are needed to explore the relationship of cervical malalignment and the development of ASD. Sagittal alignment of the cervical spine may play a substantial role in the development of cervical myelopathy as cervical deformity can lead to spinal cord compression and cord tension. Surgical correction of cervical myelopathy should always take into consideration cervical sagittal alignment, as decompression alone may not decrease cord tension induced by kyphosis. Awareness of the development of postlaminectomy kyphosis is critical as it relates to cervical myelopathy. The future direction of cervical deformity correction should include a comprehensive approach in assessing global cervicalpelvic relationships. Just as understanding pelvic incidence as it relates to lumbar lordosis was crucial in building our knowledge of thoracolumbar deformities, T-1 incidence and cervical sagittal balance can further our understanding of cervical deformities. Other important parameters that account for the cervical-pelvic relationship are surveyed in detail, and it is recognized that all such parameters need to be validated in studies that correlate HRQOL outcomes following cervical deformity correction.

Differences in treatments and outcomes for idiopathic scoliosis patients treated in the United States from 1998 to 2007: impact of socioeconomic variables and ethnicity

BACKGROUND CONTEXT

Scoliosis is a significant cause of disability and health-care resource utilization in the United States.

PURPOSE

Our aim was to evaluate potential disparities in the selection of treatments and outcomes for idiopathic scoliosis patients on a national level. To date, only one study has examined inpatient complications, discharge disposition, and mortality with respect to scoliosis treatment on a national scale.

STUDY DESIGN/SETTING

Retrospective review of cases having a primary diagnosis of idiopathic scoliosis using the nationwide inpatient sample (NIS) administrative data from 1998 to 2007.

PATIENT SAMPLE

The NIS data were queried to identify patients with a primary diagnosis of idiopathic scoliosis (International Classification of Diseases, Ninth Revision [ICD-9] diagnosis code: 737.30) admitted routinely. Surgically treated patients were identified as those patients who underwent a spinal fusion (ICD-9-Clinical Modification code: 81.08) as a principal procedure.

OUTCOME MEASURES

Rates of surgical versus nonsurgical treatments were measured as were inhospital complications and mortality rates.

METHODS

No external funding was received for this work. Univariate and multivariate analyses evaluated race, sex, socioeconomic factors, and hospital characteristics as predictors of surgical versus nonsurgical treatments, as well as inhospital complications and mortality rates.

RESULTS

The study analyzed 9,077 surgically and 1,098 nonsurgically treated patients with idiopathic scoliosis. Univariate analysis showed both patient- and hospital-level variables as strongly associated with surgical versus nonsurgical treatments and outcomes. Multivariate analysis revealed that Caucasians and private insurance patients were more likely to undergo surgical treatment (p<.05) even when controlling for comorbidities. Additionally, Caucasians had a reduced risk of nonroutine discharge compared with non-Caucasians (p=.03). Large hospitals had higher surgery rates (p=.08) than small- or medium-sized facilities and a lower risk of mortality (p=.04). Caucasians (65.1%) were more commonly admitted to large teaching hospitals than African American (59.8%) or Hispanic (41.8%) patients.

CONCLUSIONS

Differences were found in the selection of surgical versus nonsurgical treatments, as well as inhospital morbidity for hospitalized idiopathic scoliosis patients based on ethnic and socioeconomic variables. This may in part be because of differences in access to the resources of large teaching hospitals for different ethnic and socioeconomic groups or variability in severity of scoliosis among these groups that was not captured in this database.

Metastatic Leiomyosarcoma to the Spine Complicated With Thrombocytopenia

Uterine leiomyosarcomas do not frequently metastasize to the bone, and spinal column metastases are even less common. Surgery is the treatment of choice. Adjuvant radiation with or without chemotherapy depending on the extent of disease can be beneficial. We present the case of leiomyosarcoma metastasis to the spine with a previous history of known primary disease complicated by thrombocytopenia. Thrombocytopenia can present surgical challenges, but can also be present concurrently unrelated to the primary disease. A thorough evaluation is needed to rule out any underlying lymphoproliferative disorder or microangiopathic phenomenon.

Implications of the center of rotation concept for the reconstruction of anterior column lordosis and axial preloads in spinal deformity surgery

OBJECT

In thoracolumbar deformity surgery, anterior-only approaches are used for reconstruction of anterior column failures. It is generally advised that vertebral body replacements (VBRs) should be preloaded by compression. However, little is known regarding the impact of different techniques for generation of preloads and which surgical principle is best for restoration of lordosis. Therefore, the authors analyzed the effect of different surgical techniques to restore spinal alignment and lordosis as well as the ability to generate axial preloads on VBRs in anterior column reconstructions.

METHODS

The authors performed a laboratory study using 7 fresh-frozen specimens (from T-3 to S-1) to assess the ability for lordosis reconstruction of 5 techniques and their potential for increasing preloads on a modified distractable VBR in a 1-level thoracolumbar corpectomy. The testing protocol was as follows: 1) Radiographs of specimens were obtained. 2) A 1-level corpectomy was performed. 3) In alternating order, lordosis was applied using 1 of the 5 techniques. Then, preloads during insertion and after relaxation using the modified distractable VBR were assessed using a miniature load-cell incorporated in the modified distractable VBR. The modified distractable VBR was inserted into the corpectomy defect after lordosis was applied using 1) a lamina spreader; 2) the modified distractable VBR only; 3) the ArcoFix System (an angular stable plate system enabling in situ reduction); 4) a lordosizer (a customized instrument enabling reduction while replicating the intervertebral center of rotation [COR] according to the COR method); and 5) a lordosizer and top-loading screws ([LZ+TLS], distraction with the lordosizer applied on a 5.5-mm rod linked to 2 top-loading pedicle screws inserted laterally into the vertebra). Changes in the regional kyphosis angle were assessed radiographically using the Cobb method.

RESULTS

The bone mineral density of specimens was 0.72 ± 22.6 g/cm(2). The maximum regional kyphosis angle reconstructed among the 5 techniques averaged 9.7°-16.1°, and maximum axial preloads averaged 123.7-179.7 N. Concerning correction, in decreasing order the LZ+TLS, lordosizer, and ArcoFix System outperformed the lamina spreader and modified distractable VBR. The order of median values for insertion peak load, from highest to lowest, were lordosizer, LZ+TLS, and ArcoFix, which outperformed the lamina spreader and modified distractable VBR. In decreasing order, the axial preload was highest with the lordosizer and LZ+TLS, which both outperformed the lamina spreader and the modified distractable VBR. The technique enabling the greatest lordosis achieved the highest preloads. With the ArcoFix System and LZ+TLS, compression loads could be applied and were 247.8 and 190.6 N, respectively, which is significantly higher than the insertion peak load and axial preload (p < 0.05).

CONCLUSIONS

Including the ability for replication of the COR in instruments designed for anterior column reconstructions, the ability for lordosis restoration of the anterior column and axial preloads can increase, which in turn might foster fusion.

Morbidity and mortality after spinal deformity surgery in patients 75 years and older: complications and predictive factors

Object

As the population continues to age, relatively older geriatric patients will present more frequently with complex spinal deformities that may require surgical intervention. To the authors' knowledge, no study has analyzed factors predictive of complications after major spinal deformity surgery in the very elderly (75 years and older). The authors' objective was to determine the rate of minor and major complications and predictive factors in patients 75 years of age and older who underwent major spinal deformity surgery requiring a minimum 5-level arthrodesis procedure.

Methods

Twenty-one patients who were 75 years of age or older and underwent thoracic and/or lumbar fixation and arthrodesis across 5 or more levels for spinal deformity were analyzed retrospectively. The medical and surgical records were reviewed in detail. Age, diagnosis, comorbidities, operative data, hospital data, major and minor complications, and deaths were recorded. Factors predictive of perioperative complications were identified by logistic regression analysis.

Results

The mean patient age was 77 years old (range 75–83 years). There were 14 women and 7 men. The mean follow-up was 41.2 months (range 24–81 months). Fifteen patients (71%) had at least 1 comorbidity. A mean of 10.5 levels were fused (range 5–15 levels). Thirteen patients (62%) had at least 1 perioperative complication, and 8 (38%) had at least one major complication for a total of 17 complications. There were no perioperative deaths. Increasing age was predictive of any perioperative complication (p = 0.03). However, major complications were not predicted by age or comorbidities as a whole. In a subset analysis of comorbidities, only hypertension was predictive of a major complication (OR 10, 95% CI 1.3–78; p = 0.02). Long-term postoperative complications occurred in 11 patients (52%), and revision fusion surgery was necessary in 3 (14%).

Conclusions

Patients 75 years and older undergoing major spinal deformity surgery have an overall perioperative complication rate of 62%, with older age increasing the likelihood of a complication, and a long-term postoperative complication rate of 52%. Patients in this age group with a history of hypertension are 10 times more likely to incur a major perioperative complication. However, the mortality risk for these patients is not increased.

Complications and outcomes after spinal deformity surgery in the elderly: review of the existing literature and future directions

Object

The elderly population (age > 60 years) is the fastest-growing age group in the US. Spinal deformity is a major problem affecting the elderly and, therefore, the demand for surgery for spinal deformity is becoming increasingly prevalent in elderly patients. Much of the literature on surgery for adult deformity focuses on patients who are younger than 60 years, and therefore there is limited information about the complications and outcomes of surgery in the elderly population.

In this study, the authors undertook a review of the literature on spinal deformity surgery in patients older than 60 years. The authors discuss their analysis with a focus on outcomes, complications, discrepancies between individual studies, and strategies for complication avoidance.

Methods

A systematic review of the MEDLINE and PubMed databases was performed to identify articles published from 1950 to the present using the following key words: “adult scoliosis surgery” and “adult spine deformity surgery.” Exclusion criteria included patient age younger than 60 years. Data on major Oswestry Disability Index (ODI) scores, visual analog scale (VAS) scores, patient-reported outcomes, and complications were recorded.

Results

Twenty-two articles were obtained and are included in this review. The mean age was 74.2 years, and the mean follow-up period was 3 years. The mean preoperative ODI was 48.6, and the mean postoperative reduction in ODI was 24.1. The mean preoperative VAS score was 7.7 with a mean postoperative decrease of 5.2. There were 311 reported complications for 815 patients (38%) and 5 deaths for 659 patients (< 1%).

Conclusions

Elderly patient outcomes were inconsistent in the published studies. Overall, most elderly patients obtained favorable outcomes with low operative mortality following surgery for adult spinal deformity.

Minimally invasive lateral lumbar interbody fusion and transpsoas approach–related morbidity

Object

Recently, the minimally invasive, lateral retroperitoneal, transpsoas approach to the thoracolumbar spinal column has been described by various authors. This is known as the minimally invasive lateral lumbar interbody fusion. The purpose of this study is to elucidate the approach-related morbidity associated with the minimally invasive transpsoas approach to the lumbar spine. To date, there have been only a couple of reports regarding the morbidity of the transpsoas muscle approach.

Methods

A nonrandomized, prospective study utilizing a self-reported patient questionnaire was conducted between January 2006 and June 2008 at Northwestern University. Data were collected in 53 patients with a follow-up period ranging from 6 months to 3.5 years. Only 2 patients were lost to follow-up.

Results

Thirty-six percent (19 of 53) of patients reported subjective hip flexor weakness, 25% (13 of 53) anterior thigh numbness, and 23% (12 of 53) anterior thigh pain. However, 84% of the 19 patients reported complete resolution of their subjective hip flexor weakness by 6 months, and most experienced improved strength by 8 weeks. Of those reporting anterior thigh numbness and pain, 69% and 75% improved to their baseline function by the 6-month follow-up evaluations, respectively. All patients with self-reported subjective hip flexor weakness underwent examinations during subsequent clinic visits after surgery; however, these examinations did not confirm a motor deficit less than Grade 5. Subset analysis showed that the L3–4 and L4–5 levels were most often affected.

Conclusions

The minimally invasive, transpsoas muscle approach to the lumbar spine has a number of advantages. The data show that a percentage of the patients undergoing the transpsoas approach will have temporary sensory and motor symptoms related to this approach. The majority of the symptoms are thought to be related to psoas muscle inflammation and/or stretch injury to the genitofemoral nerve due to the surgical corridor traversed during the operation. No major injuries to the lumbar plexus were encountered. It is important to educate patients prior to surgery of the possibility of these largely transient symptoms.

Porcine intervertebral disc repair using allogeneic juvenile articular chondrocytes or mesenchymal stem cells

Tissue engineering strategies for intervertebral disc repair have focused on the use of autologous disc-derived chondrocytes. Difficulties with graft procurement, harvest site morbidity, and functionality, however, may limit the utility of this cell source. We used an in vivo porcine model to investigate allogeneic non-disc-derived chondrocytes and allogeneic mesenchymal stem cells (MSCs) for disc repair. After denucleation, lumbar discs were injected with either fibrin carrier alone, allogeneic juvenile chondrocytes (JCs), or allogeneic MSCs. Discs were harvested at 3, 6, and 12 months, and cell viability and functionality were assessed qualitatively and quantitatively. JC-treated discs demonstrated abundant cartilage formation at 3 months, and to a lesser extent at 6 and 12 months. For the carrier and MSC-treated groups, however, there was little evidence of proteoglycan matrix or residual notochordal/chondrocyte cells, but rather a type I/II collagen-enriched scar tissue. By contrast, JCs produced a type II collagen-rich matrix that was largely absent of type I collagen. Viable JCs were observed at all time points, whereas no evidence of viable MSCs was found. These data support the premise that committed chondrocytes are more appropriate for use in disc repair, as they are uniquely suited for survival in the ischemic disc microenvironment.

Predicting ideal spinopelvic balance in adult spinal deformity

Object

Spinopelvic balance is based on the theory that adjacent segments of the spine are related and influenced by one another. By understanding the correlation between the thoracolumbar spine and the pelvis, a concept of spinopelvic balance can be applied to adult deformity. The purpose of this study was to develop a mathematical relationship between the pelvis and spine and apply it to a population of adults who had undergone spinal deformity surgery to determine whether patients in spinopelvic balance have improved health measures.

Methods

Using values published in the literature, a mathematical relationship between the spine and pelvis was derived where pelvic incidence (PI) was divided by the sum of the lumbosacral lordosis (LL; T12–S1) plus the main thoracic kyphosis (TK; T4–12). The result was termed the spinopelvic constant (r): r = PI/(LL + TK). This was performed in patients in 2 age groups previously defined in the literature as “adult” (18–60 years of age) and “geriatric” (> 60 years). The equation was then constructed to relate an individual's measured PI to his or her predicted thoracolumbar curvature (LL + TK)p based on the age-specific spinopelvic constant: (LL + TK)p = r/PI. A retrospective review was then performed using cases involving patients who had undergone spine deformity surgery and were enrolled in our spinal deformity database. Sagittal balance, PI, and the sum of the main thoracic and lumbar curves were measured. The difference between the predicted sum of the regional curves (LL + TK)p, based on the individual's measured PI and the age-specific spinopelvic constant, and the measured sum of the regional curves (LL + TK)m was then calculated to determine the degree of spinopelvic imbalance. Health status measures were then compared.

Results

Using the formula r = PI/(TK = LL) and normative values in the literature, the adult spinopelvic constant was calculated to be −2.57, and the geriatric constant −5.45. For the second portion of the study, 41 patients met inclusion criteria (13 classified as nongeriatric adults and 28 as geriatric patients). Application of these constants found a statistically significant decline in almost all outcome categories when the spinopelvic balance showed at least 10° of kyphosis more than predicted. While not statistically significant, the trend was that better outcomes were associated with a spinopelvic balance within 0 to +10° of the predicted value. The final analysis compared and separated outcomes from sagittal balance and spinopelvic balance. For patients to be considered in sagittal balance, they must be within 50 mm (± 50 mm) of neutral. For patients to be considered in spinopelvic balance, they must be within ± 10° of predicted spinopelvic balance. Patients in both sagittal and spinopelvic balance have statistically significant better outcomes than those in neither sagittal nor spinopelvic balance. Except for the mean SF-12 PCS (12-Item Short-Form Health Survey Physical Component Summary), there were no significant differences between those that were either in sagittal or spinopelvic balance, but not the other.

Conclusions

Restoring a normative relationship between the spine and the pelvis during adult deformity correction may play an important role in determining surgical outcomes in these patients independent of sagittal balance.

Changes in coronal and sagittal plane alignment following minimally invasive direct lateral interbody fusion for the treatment of degenerative lumbar disease in adults: a radiographic study

OBJECTIVE

The lateral transpsoas approach for lumbar interbody fusion is a minimal access technique that has been used by some to treat lumbar degenerative conditions, including degenerative scoliosis. Few studies, however, have analyzed its effect on coronal and sagittal plane correction, and no study has compared changes in segmental, regional, and global coronal and sagittal alignment after this technique. The object of this study was to determine changes in sagittal and coronal plane alignment occurring after direct lateral interbody fusion (DLIF).

METHODS

The authors performed a review of the radiographic records of 36 patients with lumbar degenerative disease treated with the DLIF technique. Thirty-five patients underwent supplemental posterior fixation to maintain correction. Preoperative and postoperative standing anteroposterior and lateral lumbar radiographs were obtained in all patients for measurement of segmental and regional coronal and sagittal Cobb angles. Standing anteroposterior and lateral 36-in radiographs were also obtained in 23 patients for measurement of global coronal (center sacral vertebral line) and sagittal (C-7 plumb line) balance.

RESULTS

The mean coronal segmental Cobb angle was 4.5° preoperatively, and it was 1.5° postoperatively (p < 0.0001). The mean pre- and postoperative regional lumbar coronal Cobb angles were 7.6° and 3.6°, respectively (p = 0.0001). In 8 patients with degenerative scoliosis, the mean pre- and postoperative regional lumbar coronal Cobb angles were 21.4° and 9.7°, respectively (p = 0.0004). The mean global coronal alignment was 19.1 mm preoperatively, and it was 12.5 mm postoperatively (p < 0.05). In the sagittal plane, the mean segmental Cobb angle measured -5.3° preoperatively and -8.2° postoperatively (p < 0.0001). The mean pre- and postoperative regional lumbar lordoses were 42.1° and 46.2°, respectively (p > 0.05). The mean global sagittal alignment was 41.5 mm preoperatively and 42.4 mm postoperatively (p = 0.7). The average clinical follow-up was 21 months in 21 patients. The mean pre- and postoperative visual analog scale scores were 7.7 and 2.9, respectively (p < 0.0001). The mean pre- and postoperative Oswestry Disability Indices were 43 and 21, respectively (p < 0.0001).

CONCLUSIONS

Direct lateral interbody fusion significantly improves segmental, regional, and global coronal plane alignment in patients with degenerative lumbar disease. Although DLIF increases the segmental sagittal Cobb angle at the level of instrumentation, it does not improve regional lumbar lordosis or global sagittal alignment.

En Bloc Resection for Primary and Metastatic Tumors of the Spine

BACKGROUND

The efficacy of en bloc resection for spinal tumors is unknown because most of the current evidence is provided by small, single-institution clinical series or case reports.

OBJECTIVE

To combine all previously published reports of en bloc resection for primary and metastatic spinal tumors, to describe the overall pattern of disease-free survival, and to investigate potentially prognostic factors for recurrence.

METHODS

A complete MEDLINE search for all articles reporting survival data for en bloc resection of spinal tumors was undertaken; 44 articles met inclusion criteria from which 306 eligible patients were identified.

RESULTS

There were 229 cases of primary tumors with a mean follow-up of 65.0 months and 77 cases of solitary metastatic tumors with a mean follow-up of 26.5 months. Median time to recurrence was 113 months for the primary group and 24 months for the metastatic group. Disease-free survival rates at 1, 5, and 10 years were 92.6%, 63.2%, and 43.9%, respectively, for the primary group and 61.8%, 37.5%, and 0%, respectively, for the metastatic group; 5-year disease-free survival rates were 58.4% for chordoma and 62.9% for chondrosarcoma. After adjusting for covariates, age, male sex, metastatic tumors, and osteosarcomas were significantly associated with a tumor recurrence.

CONCLUSION

This study provides the largest published series of patients undergoing en bloc resection for spinal tumors. Median time to recurrence reached almost 10 years in patients with primary tumors; however, it was only 2 years in those with isolated metastatic tumors.

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

Object

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.

Detection of postoperative granulation tissue with an ICG-enhanced integrated OI-/X-ray System

Background

The development of postoperative granulation tissue is one of the main postoperative risks after lumbar spine surgery. This granulation tissue may lead to persistent or new clinical symptoms or complicate a follow up surgery. A sensitive non-invasive imaging technique, that could diagnose this granulation tissue at the bedside, would help to develop appropriate treatments. Thus, the purpose of this study was to establish a fast and economic imaging tool for the diagnosis of granulation tissue after lumbar spine surgery, using a new integrated Optical Imaging (OI)/X-ray imaging system and the FDA-approved fluorescent contrast agent Indocyanine Green (ICG).

Methods

12 male Sprague Dawley rats underwent intervertebral disk surgery. Imaging of the operated lumbar spine was done with the integrated OI/X-ray system at 7 and 14 days after surgery. 6 rats served as non-operated controls. OI/X-ray scans of all rats were acquired before and after intravenous injection of the FDA-approved fluorescent dye Indocyanine Green (ICG) at a dose of 1 mg/kg or 10 mg/kg. The fluorescence signal of the paravertebral soft tissues was compared between different groups of rats using Wilcoxon-tests. Lumbar spines and paravertebral soft tissues were further processed with histopathology.

Results

In both dose groups, ICG provided a significant enhancement of soft tissue in the area of surgery, which corresponded with granulation tissue on histopathology. The peak and time interval of fluorescence enhancement was significantly higher using 10 mg/kg dose of ICG compared to the 1 mg/kg ICG dose. The levels of significance were p < 0.05. Fusion of OI data with X-rays allowed an accurate anatomical localization of the enhancing granulation tissue.

Conclusion

ICG-enhanced OI is a suitable technique to diagnose granulation tissue after lumbar spine surgery. This new imaging technique may be clinically applicable for postoperative treatment monitoring. It could be also used to evaluate the effect of anti-inflammatory drugs and may even allow evaluations at the bedside with new hand-held OI scanners.

Biomechanical comparison of three fixation techniques for unstable thoracolumbar burst fractures. Laboratory investigation

OBJECT

Increased structural stability is considered sufficient justification for higher-risk surgical procedures, such as circumferential fixation after severe spinal destabilization. However, there is little biomechanical evidence to support such claims, particularly after traumatic lumbar burst fracture. The authors sought out to compare the biomechanical performance of the following 3 fixation strategies for spinal reconstruction after decompression for an unstable thoracolumbar burst fracture: 1) short-segment anterolateral fixation; 2) circumferential fixation; and 3) extended anterolateral fixation.

METHODS

Thoracolumbar spines (T10-L4) from 7 donors (mean age at death 64+/-6 years; 1 female and 6 males) were tested in pure moment loading in flexion-extension, lateral bending, and axial rotation. Thoracolumbar burst fractures were surgically induced at L-1, and testing was repeated sequentially for each of the following fixation techniques: short-segment anterolateral, circumferential, and extended anterolateral. Primary and coupled 3D motions were measured across the instrumented site (T12-L2) and compared across treatment groups.

RESULTS

Circumferential and extended anterolateral fixations were statistically equivalent for primary and off-axis range-of-motions in all loading directions, and short-segment anterolateral fixation offered significantly less rigidity than the other 2 methods.

CONCLUSIONS

The results of this study strongly suggest that extended anterolateral fixation is biomechanically comparable to circumferential fusion in the treatment of unstable thoracolumbar burst fractures with posterior column and posterior ligamentous injury. In cases in which an anterior procedure may be favored for load sharing or canal decompression, extension of the anterior instrumentation and fusion one level above and below the unstable segment can result in near equivalent stability to a 2-stage circumferential procedure.

Early Clinical & Radiographic Results of NFix II Posterior Dynamic Stabilization System

Background

Complications associated with rigid posterior instrumented fusions of the lumbar spine include pseudarthrosis, accelerated adjacent-segment disease, hardware failure, and iatrogenic fixed sagittal imbalance. Posterior pedicle screw/rod-based dynamic stabilization systems, in which semirigid rods or cords are used to restrict or control, rather than completely eliminate spinal segmental motion, aim to reduce or eliminate these fusion-associated drawbacks. In this study, we analyzed the early radiographic and clinical outcomes of patients treated with the NFix II System (N Spine, Inc., San Diego, California), a novel pedicle screw/ rod-based system used as a nonfusion posterior dynamic stabilization system, and compared our results to those of similar systems currently in use.

Methods

Seven sites participated in a retrospective assessment of 40 consecutive patients who underwent dynamic stabilization of the lumbar spine with the NFix II System at a single level. (One patient underwent 2 single-level dynamic constructs at noncontiguous levels (L3-4 and L5-S1).) Patients were included based on the presence of spinal stenosis, degenerative spondylolisthesis, adjacent segment degeneration, recurrent disc herniation, symptomatic degenerative disc disease, and degenerative scoliosis requiring dynamic stabilization at 1 level with or without instrumented rigid fusion at a contiguous level. Participants were evaluated preoperatively, with planned postoperative assessments at 3 and 6 weeks (1 center assessed patients at 4 weeks), 3 months, 6 months, and 12 months. The primary clinical outcome measures at each assessment were visual analogue scale (VAS) scores to measure back pain, and Oswestry Disability Index (ODI)¹ scores to measure function. Radiographic outcome measurements included evidence of instrumentation failure and range of motion (ROM) based on postoperative flexion-extension radiographs at 3, 6, and 12 months.

Results

Forty patients (15males, 25 females) with a mean age of 55 years (range 21–81) were included. Average follow-up was 8.1 months (range 6–12). The mean VAS score improved from 7.6 preoperatively to 3.3 postoperatively (P < .001), and the ODI score from 47.3 to 22.8 (P < .001). Eighty percent of patients were severely disabled or worse (ODI ≥ 41) preoperatively, which was reduced to 13% postoperatively. Of the 10 patients with more than 6 months’ follow-up, only 4 demonstrated adequate flexion/extension effort. ROM measurements in those 4 patients showed that on average 53% of preoperative segmental motion was retained at the dynamically stabilized level 6 months postoperatively. There were no instrumentation-related complications.

Conclusions

Results of this limited study indicate that the NFix II System when used as a nonfusion device for dynamic stabilization produces significant improvements in pain and function at short-term follow-up with outcomes comparable to other dynamic stabilization systems. The use of this system was not associated with an increased risk of instrumentation failure. The small number of patients with postoperative severe disability or worse compares favorably to long-term published data on posterolateral fusion. Lastly, in this small sample, ROM was preserved at 6-month follow-up.

Clinical Relevance

Posterior pedicle screw/rod dynamic stabilization using the NFix II System seems very effective in improving pain and function scores, at least in the short term (mean postoperative ODI of 22.8). Preservation of ROM is also possible. Longerterm follow-up is necessary to assess sustained clinical improvement, hardware complications, and maintenance in segmental ROM. The NFix II System may be considered an effective alternative to existing dynamic stabilization systems. This device is cleared by the US Food and Drug Administration for use as an adjunct to fusion and has the European CE Marking for use in both fusion and nonfusion applications.

Stabilization of the atlantoaxial complex via C-1 lateral mass and C-2 pedicle screw fixation in a multicenter clinical experience in 102 patients: modification of the Harms and Goel techniques

Object

Stabilization of the atlantoaxial complex has proven to be very challenging. Because of the high mobility of the C1–2 motion segment, fusion rates at this level have been substantially lower than those at the subaxial spine. The set of potential surgical interventions is limited by the anatomy of this region. In 2001 Jürgen Harms described a novel technique for individual fixation of the C-1 lateral mass and the C-2 pedicle by using polyaxial screws and rods. This method has been shown to confer excellent stability in biomechanical studies. Cadaveric and radiographic analyses have indicated that it is safe with respect to osseous and vascular anatomy. Clinical outcome studies and fusion rates have been limited to small case series thus far. The authors reviewed the multicenter experience with 102 patients undergoing C1–2 fusion via the polyaxial screw/rod technique. They also describe a modification to the Harms technique.

Methods

One hundred two patients (60 female and 42 male) with an average age of 62 years were included in this analysis. The average follow-up was 16.4 months. Indications for surgery were instability at the C1–2 level, and a chronic Type II odontoid fracture was the most frequent underlying cause. All patients had evidence of instability on flexion and extension studies. All underwent posterior C-1 lateral mass to C-2 pedicle or pars screw fixation, according to the method of Harms. Thirty-nine patients also underwent distraction and placement of an allograft spacer into the C1–2 joint, the authors' modification of the Harms technique. None of the patients had supplemental sublaminar wiring.

Results

All but 2 patients with at least a 12-month follow-up had radiographic evidence of fusion or lack of motion on flexion and extension films. All patients with an allograft spacer demonstrated bridging bone across the joint space on plain x-ray films and computed tomography. The C-2 root was sacrificed bilaterally in all patients. A postoperative wound infection developed in 4 patients and was treated conservatively with antibiotics and local wound care. One patient required surgical debridement of the wound. No patient suffered a neurological injury. Unfavorable anatomy precluded the use of C-2 pedicle screws in 23 patients, and thus, they underwent placement of pars screws instead.

Conclusions

Fusion of C1–2 according to the Harms technique is a safe and effective treatment modality. It is suitable for a wide variety of fracture patterns, congenital abnormalities, or other causes of atlantoaxial instability. Modification of the Harms technique with distraction and placement of an allograft spacer in the joint space may restore C1–2 height and enhance radiographic detection of fusion by demonstrating a graft–bone interface on plain x-ray films, which is easier to visualize than the C1–2 joint.

Partial spondylectomy: modification for lateralized malignant spinal column tumors of the cervical or lumbosacral spine

Total en bloc spondylectomy is a useful technique in treating primary and secondary spinal malignancies, but requires extensive instrumentation to achieve difficult fusions, and requires extensive exposure of neurovascular structures that poses additional risk of nerve root and vascular injury. More limited resections may reduce these risks, especially in the cervical or lumbosacral spine. We report a technique used in two patients with lateralized primary vertebral tumors of the cervical or lumbosacral spine where tumor removal was achieved through a partial spondylectomy. The advantages of a partial spondylectomy included: (i) avoidance of injuring contralateral neurovascular structures during exposure; and (ii) supplementation of instrumentation by additional fixation at the level of spondylectomy. Partial spondylectomy can be an alternative to total en bloc spondylectomy in properly selected patients with lateralized encapsulated malignant spinal tumors and may be performed in the cervical or lumbosacral spinal regions.

Stand-alone anterior lumbar discectomy and fusion with plate: initial experience

BACKGROUND

The stability of the lumbar spine after ALIF with lateral plate fixation and/or posterior fixation has previously been investigated; however, stand-alone ALDF with plate has not. Previous clinical studies have demonstrated poor fusion rates with stand-alone anterior interbody fusion in the absence of posterior instrumentation. We review our initial experience with stand-alone ALDF with segmental plate fixation for degenerative disc disease of the lumbar spine and compare these results with our experience with traditional ALIF and supplemental posterior instrumentation.

METHODS

Forty-nine patients treated at the University of California, San Francisco between 2002 and 2005 were included in this analysis. The study was retrospective in nature. All patients presented with discogram-positive back pain and had failed conservative treatment. Twenty-four patients underwent ALDF with plate, and 25 underwent ALIF with posterior instrumentation. Patients underwent flexion/extension imaging at 6 weeks, 3 months, 6 months, and 1 year postoperatively. All patients completed ODI and VAS questionnaires at 3 months, 6 months, and 1 year postoperatively.

RESULTS

Average follow-up was 11.6 and 21.7 months in the ALDF with plate and ALIF with instrumentation groups, respectively. All patients demonstrated radiographic evidence of fusion at last follow-up. None developed instability at the fusion level, and none developed hardware failure (plate back-out, screw lucency, etc). Average subsidence at 6 months postoperatively was 2.2 and 2.5 mm, respectively. The VAS and ODI scores are presented in Tables 3 and 4.

CONCLUSIONS

Preliminary results of stand-alone ALDF with plate suggest it may be safe and effective for the surgical treatment of patients with degenerative disc disease of the lumbar spine. Long-term follow-up is clearly needed. Subsidence is diminished with ALDF and plating compared with ALIF with posterior instrumentation. It is unclear at this time which subset of patients may ultimately require posterior hardware supplementation, but those with circumferential stenosis or severe facet disease are not ideal candidates for ALDF with plate. For some patients in whom lumbar arthroplasty is not indicated, or as a salvage procedure, ALDF with plate may be a satisfactory alternative and may eliminate the need for a supplemental posterior procedure.

Bioabsorbable anterior cervical plating: initial multicenter clinical and radiographic experience

STUDY DESIGN

Prospective clinical trial.

OBJECTIVE

The authors present their initial multicenter experience in the surgical management of 1-level degenerative disc disease of the cervical spine with anterior cervical discectomy and fusions (ACDF) using a bioabsorbable polymer plate.

SUMMARY OF BACKGROUND DATA

The introduction of a radiolucent bioabsorbable polymer plate and screws for ACDF presents a novel opportunity to gain the some of the potential added benefit of stabilization with internal immobilization while possibly reducing some of the long-term complications and imaging artifacts associated with titanium instrumentation. We prospectively analyze 52 patients who were treated at 6 different institutions across the United States with bioabsorbable polymer plate and screws for ACDF surgery.

METHODS

Patients were prospectively enrolled. A retrospective review of patients' charts and imaging was performed to determine clinical and radiographic outcome following anterior cervical spine surgery. Specifically, the authors looked at need for additional surgeries, local reaction to bioabsorbable polymer, fusion rate, and complications. Surgeries involved the C4-C5, C5-C6, C6-C7, and/or C7-T1 levels. Cadaveric bone was used in 42 patients, polyetheretherketone (PEEK) cages in 6 patients, and iliac crest autograft in 4 patients. The patients were observed for an average of 13.3 months.

RESULTS

Radiographic fusion was achieved in 98.1% (51 of 52 patients) of the cases at 6 months. One patient has evidence of nonunion on flexion-extension imaging but remains asymptomatic. A different patient developed mild kyphosis after surgery and had persistence of radicular symptoms but refused further surgery. There were no clinical signs or symptoms of reaction to the bioabsorbable material.

CONCLUSIONS

The rates of fusion following single-level ACDF with internal fixation using bioabsorbable polymer plate and screws in this study match those previously reported in the literature with metallic implants and are superior to noninstrumented fusions. Preliminary results suggest that this newly available technology for anterior fusion may be as effective as traditional titanium plating systems in single-level disease. The bioabsorbable material appears to be well tolerated by patients. A larger, randomized, controlled study is necessary to bring the results to statistical significance.

Modified paramedian transpedicular approach and spinal reconstruction for intradural tumors of the cervical and cervicothoracic spine: clinical experience

STUDY DESIGN

Retrospective review of the medical, radiographic, surgical, and postoperative records of patients who underwent resection of multilevel intradural extramedullary spinal cord tumors of the ventral cervical and cervicothoracic spine via a modified paramedian transpedicular approach at the University of California, San Francisco, between 2003 and 2005.

OBJECTIVE

To assess the surgical, clinical, and radiographic outcomes of using the modified paramedian transpedicular approach to resect ventral intradural extramedullary spinal cord tumors of the ventral cervical and cervicothoracic spine.

SUMMARY OF BACKGROUND DATA

A common theme of skull-base surgery for many years has been to remove the bone rather than retract neural elements. In this report, we demonstrate some possible advantages of taking a "spine-base" approach for resecting intradural extramedullary spinal cord tumors of the ventral cervical and cervicothoracic spinal canal, and present our clinical experience.

METHODS

All medical, surgical, and radiologic records were retrospectively reviewed. Clinical outcome was assessed for disability via the Neck Disability Index and for pain via the visual analog scale.

RESULTS

Fourteen patients (4 males and 10 females, average age 39.6 years, range 20-62) with intradural extramedullary spinal cord tumors involving multiple levels of the anterior cervical and cervicothoracic spine were identified. All patients presented with pain and/or radiculomyelopathy attributed to a ventral intradural extramedullary spinal cord tumor of the cervical or cervicothoracic spine that was resected via the modified paramedian transpedicular approach with partial dorsal corpectomy and posterior spinal reconstruction. The average follow-up period was 14.6 months (range 5-30). Gross total resection was achieved in all cases, and no patient required additional surgery via an anterior approach for residual tumor.

CONCLUSIONS

The modified paramedian transpedicular approach with partial dorsal corpectomy we describe here is a variation of traditional thoracic posterolateral transpedicular extracavitary approaches and offers direct access to lesions of the ventral cervicothoracic spinal canal. This approach avoids the morbidity of anterior transcervical, transoral, or transthoracic procedures, while providing a view of the entire ventral cervicothoracic canal, and can be performed safely and effectively in select patients.

Corpectomy followed by the placement of instrumentation with titanium cages and recombinant human bone morphogenetic protein–2 for vertebral osteomyelitis

Object

The treatment of vertebral osteomyelitis includes antibiotics with or without surgical intervention. The decision to place instrumentation into an infected spinal column remains controversial. The use of recombinant human bone morphogenetic protein–2 (rhBMP-2) in patients with osteomyelitis is also extremely controversial. The authors review their experience in performing corpectomy and fusion with titanium cages and rhBMP-2 in patients with vertebral instability and/or neurological compromise due to vertebral osteomyelitis.

Methods

Data obtained in 15 patients treated between 2001 and 2005 were included in this analysis. Nine patients presented primarily with axial pain and six with radiculopathy or myelopathy. Seven patients had an associated epidural abscess. The cervical spine was affected in six patients, the thoracic spine in five, and the lumbar spine in four. All patients underwent corpectomy of the involved vertebral bodies; the authors then performed spinal reconstruction, placing a titanium cage–plate system with morcellized allograft/autograft and rhBMP-2. In 10 patients, supplemental posterolateral screw–rod fixation was conducted.

A one-level corpectomy was performed in one patient, a two-level corpectomy in 13, and a six-level corpectomy in one. A morcellized allograft and rhBMP-2–filled titanium cage was used in 10 patients, and an autograft and rhBMP-2–filled cage in five patients. The most common pathogen wasStaphylococcus aureus. All patients received intravenous antibiotics for at least 6 weeks postoperatively, and life-long antibiotic therapy was required in three patients with coccidiomycoses, candida, and tuberculosis osteomyelitis, respectively. There were no recurrent infections. Radiography demonstrated evidence of fusion in all patients at the last follow-up examination. The mean follow-up period was 20 months.

Conclusions

Corpectomy followed by titanium cage–plate reconstruction and the placement of rhBMP-2 may be a safe and effective treatment for selected patients with vertebral osteomyelitis. This surgical therapy does not appear, at least based on preliminary results, to lead to recurrent hardware infections. Based on the results obtained in this limited series, the authors found that rhBMP-2 can be used in the setting of active infection with excellent fusion rates and without complication. The morbidity associated with the autograft donor site is avoided when using cages. Antibiotic therapy tailored to the specific organism should be continued for at least 6 weeks after surgery, and life-long therapy is required in cases of fungal or tuberculosis infections.

Recent advances: Infections of the spine

The global increase of spinal infections is concomitant with the rise of its risk factors, including HIV/AIDS, diabetes mellitus, intravenous drug use, advanced age, and gunshot wounds to the spine. Because spinal infections have a wide span of presentation, early detection and differentiation are notoriously challenging. Current advances in laboratory and imaging techniques, such as polymerase chain reaction, fluorodeoxyglucose positron emission tomography, and 99mTc-ciprofloxacin scintigraphy, allow for better diagnostic rendering of the infection and its degree of spinal involvement. Less invasive surgical procedures and preventive surgical management have helped reduce spinal infection morbidities such as deformity and neurologic deficit. Although proper antibiotic regimen and correct surgical management are of vital importance to successful patient outcome, early detection remains the most critical factor.

Successful outcome of six-level cervicothoracic corpectomy and circumferential reconstruction: case report and review of literature on multilevel cervicothoracic corpectomy

The authors report the successful outcome of a six-level corpectomy across the cervico-thoracic spine with circumferential reconstruction in a patient with extensive osteomyelitis of the cervical and upper thoracic spine. To the authors’ knowledge, this is the first report of a corpectomy extending across six levels of the cervico-thoracic spine. Clinical relevance: the authors recommend anterior cage and plate-assisted reconstruction and additional posterior instrumentation using modern spinal surgical techniques and implants.

Current treatment strategies and outcomes in the management of symptomatic vertebral hemangiomas

OBJECTIVE

We analyzed the outcome of patients with symptomatic vertebral hemangiomas treated at University of California, San Francisco, over a 20 year period. Treatment included transarterial embolization, embolization followed by surgical decompression or vertebral reconstruction with arthrodesis, and percutaneous vertebroplasty alone.

METHODS

All medical, surgical, and radiological records were reviewed retrospectively. All patients underwent follow-up neurological examination and evaluation of back pain.

RESULTS

Sixteen patients diagnosed with symptomatic vertebral hemangiomas causing pain or neurological deficit were treated at University of California, San Francisco, between 1984 and 2004. Mean follow-up was 81 months. Seven of nine patients undergoing surgical decompression and tumor resection reported pain relief and demonstrated improvement in neurological deficit when present. Two patients had recurrent myelopathy: one was successfully treated with a second decompressive surgery, whereas the second underwent a staged vertebrectomy. All three patients undergoing vertebrectomy had cord compression from extraosseous tumor growth. Preoperative embolization reduced expected intraoperative blood loss in four patients. Three of four patients who underwent transarterial embolization alone experienced resolution of back pain. Two of four patients treated with vertebroplasty had long-term pain relief.

CONCLUSION

Transarterial embolization followed by laminectomy is a safe and effective procedure for the treatment of cord compression by vertebral hemangioma causing stenosis without instability or deformity. Vertebrectomy preceded by embolization and followed by reconstruction can be used to treat cord compression from extraosseous tumor extension. Transarterial embolization without decompression is an effective treatment for painful intraosseous hemangiomas. Vertebroplasty is useful for improving pain symptoms, especially when vertebral body compression fracture has occurred in patients without neurological deficit, but is less effective in providing long-term pain relief.