Infinity: A Prospective Trial for Safety and Accuracy of Navigated Posterior Cervical and Thoracic Instrumentation in long-segment Fusions.

STUDY DESIGN: Unblinded single-arm prospective clinical trial. OBJECTIVE: Evaluate safety and accuracy of navigation for placement of posterior cervicothoracic instrumentation. SUMMARY OF BACKGROUND DATA: Computer assisted stereotactic navigation for placement of spinal instrumentation has been widely studied and implemented in the thoracic and lumbar spine. However less literature exists regarding the use of computer assisted navigation for posterior cervical instrumentation, particularly with lateral mass fixation. Here we present the first prospective study of navigated cervical lateral mass screw placement for cervicothoracic fusion. METHODS: Patients who met indications for posterior cervical fusion were screened, consented, and enrolled preoperatively for instrumentation with Medtronic Infinity Occipital-Cervical-Thoracic implants, with use of intraoperative O-arm and stereotactic Stealth navigation. Postoperative CTs of the instrumented levels were obtained during the same hospital admission. Primary outcome of the trial was safety. Secondary outcomes were screw accuracy assessed by Gertzbein-Robbins grade, neurologic exams, and patient reported outcomes on the PROMIS 29 questionnaire. RESULTS: A total of 50 patients underwent surgery, and 557 screws were placed. There were no adverse events related to the use of navigation or screw malposition. Gertzbein-Robbins grade A or B placement comprised 95% of navigated screws. There was a decrease in positive Hoffmann sign rate postoperatively, and sensory and motor exams remained stable. There was improvement in patient reported pain and sleep domains. CONCLUSIONS: Navigation for cervicothoracic instrumentation is safe overall and leads to high rates of accurately placed screws. Longer term follow up could provide more insight to whether the use of this technology results in durable improvement in spinal alignment parameters and patient reported outcomes. LEVEL OF EVIDENCE: 3.

Baseline parameters and the prediction of treatment failure in patients with intravenous drug use-associated spinal epidural abscesses.

OBJECTIVE: Despite the increasing incidence of spinal epidural abscess (SEA), the baseline parameters potentially predictive of treatment failure remain poorly characterized. In this study, the authors identify the relevant baseline parameters that predict multimodal treatment failure in patients with either intravenous drug use (IVDU)-associated SEA or non-IVDU-associated SEA. METHODS: The authors reviewed the electronic medical records of a large institutional series of consecutive patients with diagnosed SEA between January 2011 and December 2017 to characterize epidemiological trends as well as the complement of baseline measures that are predictive of failure after multimodal treatment in patients with and without concomitant IVDU. The independent impact of clinical and imaging factors in detecting treatment failure was assessed by performing stepwise binary logistic regression analysis. RESULTS: A total of 324 consecutive patients with diagnosed SEA were identified. Overall, 226 patients (69.8%) had SEA related to other causes and 98 (30.2%) had a history of recent IVDU. While non-IVDU SEA admission rates remained constant, year-over-year admissions of patients with IVDU SEA nearly tripled. At baseline, patients with IVDU SEA were distinct in many respects including younger age, greater unemployment and disability, less frequent diabetes mellitus (DM), and more frequent methicillin-resistant Staphylococcus aureus infection. However, differences in length of stay, loss to follow-up, and treatment failure did not reach statistical significance between the groups. The authors constructed independent multivariate logistic regression models for treatment failure based on identified parameters in the two cohorts. For the non-IVDU cohort, the authors identified four variables as independent factors: DM, hepatitis B/C, osteomyelitis, and compression deformity severity. In contrast, for patients with IVDU, the authors identified three variables: albumin, endocarditis, and endplate destruction. Receiver operating characteristic and area under the curve (AUC) analyses were undertaken for the multivariate models predicting the likelihood of treatment failure in the two cohorts (AUC = 0.88 and 0.89, respectively), demonstrating that the derived models could adequately predict the risk of multimodal treatment failure. Treatment failure risk factor point scales were derived for the identified variables separately for both cohorts. CONCLUSIONS: Patients with IVDU SEA represent a unique population with a distinct set of baseline parameters that predict treatment failure. Identification of relevant prognosticating factors will allow for the design of tailored treatment and follow-up regimens.

Unilateral atlantoaxial pseudoarticulation: A case report, literature review, and proposed mechanism.

BACKGROUND: Atlantoaxial pseudoarticulation rarely involves the cervical spine, and its etiology is unclear. In theory, pseudoarticulation is comparable to Bertolotti's syndrome in the lumbar spine or may be attributed to an aberrant focal fusion between C0-C1-C2 that occurs during the gastrulation of embryologic development. CASE DESCRIPTION: A 39-year-old female presented with neck pain and upper extremity weakness. Magnetic resonance/computed tomography studies documented a left-sided unilateral pseudoarticulation between the lamina of C1 and C2 causing compression of the dorsal spinal cord. Following resection of the accessory C1/C2 joint utilizing a C1 hemilaminectomy and partial C2 laminectomy, the patient's neck pain and weakness resolved. Histologically, the tissue showed benign osteocartilaginous tissue with no synovial capsule. CONCLUSION: Here, the authors present a case of occiput-C1-C2 pseudojoint formation, leading to clinical and radiographic findings of cord compression due to boney outgrowth.

Impact of the Inclusion of C2 in Posterior Cervical Fusions for Cervical Myelopathy on Sagittal Cervical Alignment.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To determine the impact of including C2 in posterior fusions on radiographic parameters of cervical alignment in cervical spondylotic myelopathy. SUMMARY OF BACKGROUND DATA: Despite the use of posterior instrumentation and arthrodesis after cervical laminectomy, loss of lordosis and the development of kyphosis are prevalent. Inadequate cervical lordosis and other measures of sagittal cervical alignment have been shown to correlate with disability, general health scores, and severity of myelopathy. The role of C2 in the posterior tension band, which maintains sagittal alignment, differs from the subaxial spine, as it is the insertion point for erector spinae muscles that play a critical role in maintaining posture. PATIENTS AND METHODS: This study compares the radiographic outcomes of sagittal balance between 2 cohorts of patients who underwent posterior cervical decompression and fusion for cervical myelopathy over a 12-year period at a single institution. Demographic and surgical characteristics were collected using the electronic medical record of patients undergoing posterior cervical fusions (PCF) which included the axis [axial fusion (AF)] and those that were subaxial fusions (SAF). Radiographic measurements included preopertaive and postoperative C2-C7 lordosis (CL), C2-C7 sagittal vertical axis (SVA), and T1 slope (T1S). RESULTS: After review of the electronic medical records, 229 patients were identified as having PCF and decompression for treatment of myelopathy. One hundred sixty-seven patients had AF, whereas 62 had SAF. PCF resulted in loss of CL in both cohorts. Although there was no statistical difference in postoperative CL, there was a significant increase in SVA (P<0.001) and T1S (P<0.001) with AF. CONCLUSIONS: PCF often result in loss of lordosis. When compared with SAF, inclusion of C2 into the fusion construct may result in worsened sagittal balance, increasing the SVA and T1S.

C1-2 facet disarticulation for correction of iatrogenic cervical kyphosis following occipital-cervical fusion.

The patient is a 69-year-old woman with a history of atlantoaxial instability and cervical pain who underwent an occipital-cervical fusion at an outside hospital. Five days following the procedure she required a PEG tube due to progressive dysphagia. Compared with preoperative imaging, x-ray shows cervical spine hyperextension with a significant decrease in the occipital-C2 angle. A swallow test confirmed aspiration and pharyngeal phase functional impairment. Two-stage surgery consisted of hardware removal, drilling the fused right C1-2 facet, reinstrumentation, and halo placement. The swallowing test confirmed there is no aspiration. We proceeded with rod placement. The patient recovered completely. The video can be found here: https://youtu.be/YzdJrOm46Y4.

Biomechanical assessment of proximal junctional semi-rigid fixation in long-segment thoracolumbar constructs.

OBJECTIVEProximal junctional kyphosis (PJK) and failure (PJF) are potentially catastrophic complications that result from abrupt changes in stress across rigid instrumented and mobile non-fused segments of the spine (transition zone) after adult spinal deformity surgery. Recently, data have indicated that extension (widening) of the transitional zone via use of proximal junctional (PJ) semi-rigid fixation can mitigate this complication. To assess the biomechanical effectiveness of 3 semi-rigid fixation constructs (compared to pedicle screw fixation alone), the authors performed cadaveric studies that measured the extent of PJ motion and intradiscal pressure changes (ΔIDP).METHODSTo measure flexibility and ΔIDP at the PJ segments, moments in flexion, extension, lateral bending (LB), and torsion were conducted in 13 fresh-frozen human cadaveric specimens. Five testing cycles were conducted, including intact (INT), T10-L2 pedicle screw-rod fixation alone (PSF), supplemental hybrid T9 Mersilene tape insertion (MT), hybrid T9 sublaminar band insertion (SLB1), and hybrid T8/T9 sublaminar band insertion (SLB2).RESULTSCompared to PSF, SLB1 significantly reduced flexibility at the level rostral to the upper-instrumented vertebral level (UIV+1) under moments in 3 directions (flexion, LB, and torsion, p ≤ 0.01). SLB2 significantly reduced motion in all directions at UIV+1 (flexion, extension, LB, torsion, p < 0.05) and at UIV+2 (LB, torsion, p ≤ 0.03). MT only reduced flexibility in extension at UIV+1 (p = 0.02). All 3 constructs revealed significant reductions in ΔIDP at UIV+1 in flexion (MT, SLB1, SLB2, p ≤ 0.02) and torsion (MT, SLB1, SLB2, p ≤ 0.05), while SLB1 and SLB2 significantly reduced ΔIDP in extension (SLB1, SLB2, p ≤ 0.02) and SLB2 reduced ΔIDP in LB (p = 0.05). At UIV+2, SLB2 similarly significantly reduced ΔIDP in extension, LB, and torsion (p ≤ 0.05).CONCLUSIONSCompared to MT, the SLB1 and SLB2 constructs significantly reduced flexibility and ΔIDP in various directions through the application of robust anteroposterior force vectors at UIV+1 and UIV+2. These findings indicate that semi-rigid sublaminar banding can most effectively expand the transition zone and mitigate stresses at the PJ levels of long-segment thoracolumbar constructs.

Effect of Surgery on Gait and Sensory Motor Performance in Patients With Cervical Spondylotic Myelopathy.

BACKGROUND: Cervical spondylotic myelopathy (CSM) is a common disease of aging that leads to gait instability resulting from loss of leg sensory and motor functions. The results of surgical intervention have been studied using a variety of methods, but no test has been reported that objectively measures integrative leg motor sensory functions in CSM patients. OBJECTIVE: To determine the feasibility of using a novel single leg squat (SLS) test to measure integrative motor sensory functions in patients with CSM before and after surgery. METHODS: Fifteen patients with CSM were enrolled in this prospective study. Clinical data and scores from standard outcomes questionnaires were obtained before and after surgery. Patients also participated in experimental test protocols consisting of standard kinematic gait testing, the Purdue pegboard test, and the novel SLS test. RESULTS: The SLS test protocol was well tolerated by CSM patients and generated objective performance data over short test periods. In patients who participated in postoperative testing, the group measures of mean SLS errors decreased following surgery. Gait velocity measures followed a similar pattern of group improvement postoperatively. Practical barriers to implementing this extensive battery of tests resulted in subject attrition over time. Compared with kinematic gait testing, the SLS protocol required less space and could be effectively implemented more efficiently. CONCLUSIONS: The SLS test provides a practical means of obtaining objective measures of leg motor sensory functions in patients with CSM. Additional testing with a larger cohort of patients is required to use SLS data to rigorously examine group treatment effects. ABBREVIATIONS: BW, body weightCSM, cervical spondylotic myelopathymJOA, modified Japanese Orthopedic AssociationSLS, single leg squat.

The Application of the Revised Condyle-C1 Interval Method to Diagnose Traumatic Atlanto-occipital Dissociation in Adults.

STUDY DESIGN: Retrospective study. OBJECTIVE: Traumatic atlanto-occipital dissociation (AOD) remains a diagnostic challenge, and delay in diagnosis is associated with catastrophic outcomes. Recently, a revised version of the condyl-C1 interval (CCI) utilizing parasagittal computed tomography (CT) reconstruction was used successfully with unilateral dislocation of 2.5 mm at the level of that joint diagnostic of AOD. We report the utility of this simple technique in the diagnosis of six patients with AOD. METHODS: Two blinded neurosurgeons assessed CTs of six patients with AOD and 30 patients without AOD. The following methodologies were applied: basion-dens interval (BDI), basion-axial interval (BAI), Lee X-lines, Powers ratio, CCI, and revised CCI. The average sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) as well as the kappa statistic indicating interrater reliability of each method were investigated. RESULTS: The average sensitivity for BDI, BAI, Lee X-lines, Power ratio, CCI, and revised CCI was 0.75, 0.33, 0.67, 0.50, 1.00, and 1.00, respectively. The average specificity was 1.00, 1.00, 0.50, 1.00, 0.94, and 1.00, respectively. The average PPV was 1.00, 1.00, 0.25, 1.00, 0.80, and 1.00, respectively. The average NPV was 0.96, 0.88, 0.89, 0.91, 1.00, and 1.00, respectively, and the kappa statistic was 0.57, 0.25, 0.25, 0.20, 1.00, and 1.00, respectively. CONCLUSION: Based on this study, the revised CCI method is simple yet the most sensitive and reliable technique for the diagnosis of AOD.

Successful Treatment of a Three-Column Thoracic Extension Injury with Recumbency.

We report a unique instance of a 66-year-old male patient with an unstable three-column thoracic extension injury at the level of T4/5 who was treated with recumbency and bracing without surgery. A posterior long segment fixation was attempted three times on two separate occasions over the course of a week with failure due to difficulty in ventilating the patient during prone positioning, cardiopulmonary arrest, and hemodynamic instability during prone positioning for surgery. The decision then was to treat this fracture with recumbency. He was fitted with a thoracolumbosacral orthosis (TLSO), and was kept on bed rest for eight weeks. The patient's activity was advanced to head of bed for 45 degrees for four weeks and then to 90 degrees for four other weeks. At his 16th week visit, the patient was asymptomatic, and a computer tomography (CT) scan and magnetic resonance imaging (MRI) of the thoracic spine demonstrated evidence of osteophyte bridging and restoration of normal alignment. Three-column thoracic extension injuries can be successfully treated with recumbency in poor surgical candidates.

Effects of brain derived neurotrophic factor Val66Met polymorphism in patients with cervical spondylotic myelopathy.

Cervical spondylotic myelopathy (CSM) is the leading cause of spinal cord related disability in the elderly. It results from degenerative narrowing of the spinal canal, which causes spinal cord compression. This leads to gait instability, loss of dexterity, weakness, numbness and urinary dysfunction. There has been indirect data that implicates a genetic component to CSM. Such a finding may contribute to the variety in presentation and outcome in this patient population. The Val66Met polymorphism, a mutation in the brain derived neurotrophic factor (BDNF) gene, has been implicated in a number of brain and psychological conditions, and here we investigate its role in CSM. Ten subjects diagnosed with CSM were enrolled in this prospective study. Baseline clinical evaluation using the modified Japanese Orthopaedic Association (mJOA) scale, Nurick and 36-Item Short Form Health Survey (SF-36) were collected. Each subject underwent objective testing with gait kinematics, as well as hand functioning using the Purdue Peg Board. Blood samples were analyzed for the BDNF Val66Met mutation. The prevalence of the Val66Met mutation in this study was 60% amongst CSM patients compared to 32% in the general population. Individuals with abnormal Met allele had worse baseline mJOA and Nurick scores. Moreover, baseline gait kinematics and hand functioning testing were worse compared to their wild type counterpart. BDNF Val66Met mutation has a higher prevalence in CSM compared to the general population. Those with BDNF mutation have a worse clinical presentation compared to the wild type counterpart. These findings suggest implication of the BDNF mutation in the development and severity of CSM.

Vertebroplasty plus short segment pedicle screw fixation in a burst fracture model in cadaveric spines.

The current project investigates the role of vertebroplasty in supplementing short segment (SS) posterior instrumentation, only one level above and below a fracture. In the treatment of thoracolumbar burst fractures, long segment (LS) posterior instrumentation two levels above and below the fracture level has been used. In our study, burst fractures were produced at L1 in eight fresh frozen human cadaveric spines. The spines were then tested in three conditions: 1) intact, 2) after LS (T11-L3), 3) SS (T12-L2) instrumentation with pedicle screws and rods, and 4) short segment instrumentation plus cement augmentation of the fracture level (SSC). LS instrumentation was found to significantly reduce the motion at the instrumented level (T12-L2) as well as the levels immediately adjacent in flexion, extension and lateral bending. Similarly, SSC augmentation was found to significantly reduce the motion compared to intact at T12-L2 but still maintained the adjacent level motion. However, SS instrumentation alone did not significantly reduce the motion at T12-L2 except for left lateral bending. While LS instrumentation remains the most stable construct, SS instrumentation augmented with vertebroplasty at the fracture level increases rigidity in flexion, extension and right lateral bending beyond SS instrumentation alone.

Biomechanical analysis of anterior versus posterior instrumentation following a thoracolumbar corpectomy: Laboratory investigation.

OBJECT: The objective of this study was to evaluate the biomechanical properties of lateral instrumentation compared with short- and long-segment pedicle screw constructs following an L-1 corpectomy and reconstruction with an expandable cage. METHODS: Eight human cadaveric T10-L4 spines underwent an L-1 corpectomy followed by placement of an expandable cage. The spines then underwent placement of lateral instrumentation consisting of 4 monoaxial screws and 2 rods with 2 cross-connectors, short-segment pedicle screw fixation involving 1 level above and below the corpectomy, and long-segment pedicle screw fixation (2 levels above and below). The order of instrumentation was randomized in the 8 specimens. Testing was conducted for each fixation technique. The spines were tested with a pure moment of 6 Nm in all 6 degrees of freedom (flexion, extension, right and left lateral bending, and right and left axial rotation). RESULTS: In flexion, extension, and left/right lateral bending, posterior long-segment instrumentation had significantly less motion compared with the intact state. Additionally, posterior long-segment instrumentation was significantly more rigid than short-segment and lateral instrumentation in flexion, extension, and left/right lateral bending. In axial rotation, the posterior long-segment construct as well as lateral instrumentation were not significantly more rigid than the intact state. The posterior long-segment construct was the most rigid in all 6 degrees of freedom. CONCLUSIONS: In the setting of highly unstable fractures requiring anterior reconstruction, and involving all 3 columns, long-segment posterior pedicle screw constructs are the most rigid.

Effect of steerable cage placement during minimally invasive transforaminal lumbar interbody fusion on lumbar lordosis.

Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is commonly used for the treatment of a variety of degenerative spine disorders. Recently, steerable interbody cages have been developed which potentially allow for greater restoration of lumbar lordosis. Here we describe a technique and radiographic results following minimally invasive placement of steerable cages through a bilateral approach. A retrospective review was conducted of the charts and radiographs of 15 consecutive patients who underwent 19 levels of bilateral MIS-TLIF with the placement of steerable cages. These were compared to 10 patients who underwent 16 levels of unilateral MIS-TLIF with the placement of bullet cages. The average age, body mass index, distribution of the levels operated and follow-up were similar in both groups. The average height of the steerable cage placed was 10.9 mm compared to 8.5mm for bullet cages. The preoperative focal Cobb's angle per level was similar between both groups with a mean of -5.3 degrees for the steerable cage group and -4.8 degrees for the bullet cage group. There was a significant improvement in postoperative Cobb's angle after placement of a steerable cage with a mean of -13.7 (p<0.01) and this persisted at the last follow-up with -13 degrees (p<0.01). There was no significant change in Cobb's angle after bullet cage placement with -5.7 degrees postoperatively and a return to the baseline preoperative Cobb's angle of -4.8 at the last follow-up. Steerable cage placement for MIS-TLIF improves focal lordosis compared to bullet cage placement.

Posterior ligamentous complex healing following disruption in thoracolumbar fractures.

Classification schemes for thoracolumbar fractures attempt to categorize them as either stable or unstable. Stable fractures heal with conservative treatment strategies such as bracing, while unstable fractures require operative internal fixation. Until recently, most classification schemes recognized the importance of the pattern and location of bony disruption in segregating stable and unstable fractures. Recently, the integrity of the posterior ligamentous complex was found to influence the degree of the stability of thoracolumbar fractures. Disruption of the intervertebral disc and ligaments increases spinal instability. Unlike bone, it is thought that these ligaments do not have the capacity to heal. However, this notion is not founded by substantial evidence. It is, hence, important to determine the extent of ligamentous healing in the spine as this will influence directing therapy towards not only bony fusion, but also ligamentous union.

Traumatic intracranial hemorrhage in patients taking dabigatran: report of 3 cases and review of the literature.

BACKGROUND AND IMPORTANCE: Dabigatran is a direct thrombin inhibitor gaining popularity as a stroke prevention agent in patients with atrial fibrillation. In comparison with warfarin, dabigatran showed superiority in stroke prevention, but lower rates of major hemorrhage and intracerebral hemorrhage. Although warfarin has a well-established reversal strategy, there is far less experience reversing dabigatran. CLINICAL PRESENTATION: We present our experience with 3 patients who experienced an intracranial hemorrhage either spontaneously or after low-energy cranial trauma and review the available literature describing dabigatran use in patients with traumatic brain injury. CONCLUSION: Intracranial hemorrhage in patients taking anticoagulants and/or antiplatelets can have either a benign or malignant clinical course. At this time, there is little experience with dabigatran reversal; however, several strategies for rapid reversal have been proposed. All patients with intracranial hemorrhage taking dabigatran should be admitted for close neurological monitoring and serial imaging.

Clinical and radiographic predictors of neurological outcome following posterior fossa decompression for spontaneous cerebellar hemorrhage.

Spontaneous cerebellar hemorrhage often requires surgical suboccipital decompression and clot evacuation. Predictors of postoperative neurological deficits and outcome are not widely addressed in the literature. A retrospective review was conducted on 37 consecutive patients with the diagnosis of cerebellar hemorrhage requiring suboccipital decompression and clot evacuation. Clinical and radiographic variables were analyzed. Outcome measures were postoperative Glasgow Coma Scale (GCS) score, and long-term outcome measured by Rankin score and Glasgow Outcome Scale (GOS) score. A multivariate statistical analysis was conducted. The average age of patients was 71.1 years. There was significant improvement of neurological exam from a mean preoperative GCS score of 8.8 to a mean postoperative GCS score of 13.0. The mortality rate was 37.9%. According to the Rankin scale, 58.6% were functionally independent, 3.4% had a moderate disability, and none had a major disability or was in a vegetative state. Using GOS score, 62.1% had a favorable outcome. The presence of multiple comorbidities was associated with worse postoperative GCS and long-term outcome. A worse preoperative neurological exam, age older than 70 years, and the presence of intraventricular hemorrhage correlated only with a worse postoperative exam but not with the long-term outcome. Patients improve neurologically after posterior fossa decompression for cerebellar hemorrhage and a high percentage attain long-term functional outcome. Only the presence of multiple clinical comorbidities was associated with a worse outcome. Since there are no other preoperative predictors of long-term outcome, we recommend suboccipital decompression, when indicated, for patients with cerebellar hemorrhage regardless of age, hematoma size, or preoperative neurological exam.