Patient physiology influences the MRI-based vertebral bone quality score.

BACKGROUND CONTEXT: Osteoporosis is a critical issue affecting postmenopausal women and the aging population. A novel magnetic resonance imaging (MRI)-based vertebral bone quality (VBQ) score has been proposed as a method to identify poor bone quality and predict fragility fractures. The diagnostic accuracy of this tool is not well understood. PURPOSE: To examine the ability of VBQ to predict osteoporosis and osteopenia, its correlation with dual-energy x-ray absorptiometry (DEXA), and the influence of patient-specific factors upon the score. STUDY DESIGN: Retrospective cohort study. PATIENT SAMPLE: Patients over the age of 18 with a DEXA scan and noncontrast, T1-weighted MRI of the lumbar spine completed within a 2-year period. OUTCOME MEASURES: Area-under-curve (AUC) values of the VBQ score predicting osteopenia and osteoporosis when controlling for patient characteristics. METHODS: Patients with noncontrast, T1-weighted MRIs of the lumbar spine and DEXA scans completed within a 2-year time frame were retrospectively reviewed. Patient demographics and medical risk factors for osteoporosis were identified and compared. VBQ scores were measured by two trained researchers and interrater reliability was calculated. Patients were separated into three groups defined by lowest DEXA T-score: Healthy Bone, Osteopenia, and Osteoporosis. analysis of variance, Kruskal-Wallis test, chi-square, t tests, Mann-Whitney U tests, and multivariate linear regression were performed to examine the relationship between patient characteristics, DEXA t-scores, and VBQ scores. Receiver operating characteristic analysis and AUC values were generated for the prediction of osteopenia and osteoporosis. RESULTS: A total of 156 patients were included for analysis. Sufficient inter-rater reliability was determined for VBQ measures (intraclass correlation coefficient: 0.81). Most patients were female (83%), postmenopausal (81%), and had hyperlipidemia (64%). Patients with hyperlipidemia and healthy bone density by DEXA had elevated baseline VBQ scores (p<.001) reflective of values seen in osteopenia and osteoporosis. The AUC of the VBQ score predicting osteopenia and osteoporosis changed to be more concordant with DEXA results after controlling for hyperlipidemia (AUC=0.72, 0.70 vs. AUC=0.88, 0.89; p<.001). Sub-analysis of hyperlipidemia subtypes revealed that elevated high-density lipoprotein is associated with elevated VBQ scores. CONCLUSIONS: Hyperlipidemia increased the MRI-based VBQ score in our healthy bone population. The high signal intensities resembled values seen in osteopenia and osteoporosis, suggesting that physiologic variables which impact bone composition may influence the VBQ score. Specifically, elevated high-density lipoprotein may contribute to this. The microarchitectural changes and the clinical implications of these factors need further exploration.

Nerve Root Sedimentation Sign: Can It Predict the Success for Surgical Intervention in Patients With Symptomatic Lumbar Spinal Stenosis?

INTRODUCTION:  The use of interspinous process devices are less invasive surgical methods designed to manage mild to moderate lumbar spinal stenosis symptoms. Symptomatic relief may not be seen in all patients undergoing this procedure. Magnetic resonance imaging (MRI) parameters have been used to predict the success of clinical outcomes in patients with symptomatic lumbar spinal stenosis for decompressive surgeries. The purpose of this study was to determine the feasibility of using nerve root sedimentation sign to predict mid- to long-term clinical outcomes of patients treated with interspinous spacers for lumbar spinal stenosis. METHODS: This was a retrospective study using prospective multicenter Food and Drug Administration Investigational Device Exemption (FDA IDE) trial (Superion™ and X-STOP®) data. Inclusion criteria were patients treated with interspinous spacers, aged 45 or older with lumbar spinal stenosis at one or more contiguous levels from L1 to L5 and symptoms of neurogenic claudication. Preoperative axial T2 weighted MRI images were used to determine nerve root sedimentation sign. Preoperative, six-week, one- and two-year postoperative clinical outcomes were measured using Oswestry Disability Index (ODI) scores. Clinical outcomes were compared between positive and negative nerve root sedimentation sign groups; p ≤0.05 was considered significant. RESULTS: This study included n=374 patients; 40 excluded; 334 included (113=positive nerve root sedimentation sign (NRSS) (34%) and 221=negative NRSS (66%)). At six weeks, significant postoperative ODI correction was noted in both groups (p<0.001). No significant differences in ODI scores were identified between groups. A subgroup analysis with MRI image quality grade 3 and certainty determination grade 5, six-week postoperative ODI correction was significant in both groups. Six-week, one- and two-year postoperative ODI scores were greater by 6 points in the positive nerve root sedimentation sign group compared to the negative nerve root sedimentation sign group. CONCLUSIONS:  Although satisfactory postoperative improvement occurred in both groups, there were statistically significant differences noted in certain sub-categories. The subgroup analysis indicated MRI image quality and nerve root sedimentation sign certainty of determination may be factors that may aid with planning the surgical management of lumbar spinal stenosis.

Employment Status for the First Decade Following Randomization to Cervical Disc Arthroplasty Versus Fusion.

STUDY DESIGN: An analysis of employment status data up to 10 years following the Federal Drug Administration (FDA) Investigational Device Exemption (IDE) randomized trial and extension as post-approval study comparing BRYAN cervical disc (Medtronic, Minneapolis, MN) arthroplasty (CDA) versus single-level anterior cervical discectomy and fusion (ACDF) was performed. OBJECTIVE: Ten-year experience with the BRYAN disc arthroplasty trial provides opportunity to report patient employment data. SUMMARY OF BACKGROUND DATA: The long-term consequences of arthroplasty remain incomplete, including the occurrence of occupational compromise. METHODS: Patients' employment status were measured at regular intervals in both groups up to 10 years. RESULTS: The preoperative employment status proportion was comparable between investigational (BRYAN CDA) and control (ACDF) groups. In the investigational group, 49.2% returned to work at 6 weeks compared with 39.4% of the control group (P = 0.046). At 6 months and 2 years postoperatively, there was a similar likelihood of active employment in both groups. After 2 years at all time points, 10% drop-off seen in control group employment, but not in investigational group. At 10 years, 76.2% CDA patients were employed to 64.1% ACDF patients (P = 0.057). Preoperative variables influencing work status at 10 years following CDA included: preoperative work status, age, and SF-36 Mental Component Score (SF-36 MCS); whereas, no significant preoperative factor identified with ACDF. Time to return to work was influenced in both groups by preoperative work status; and in the ACDF group: reaching age 65 at 10-year visit, preoperative arm pain and NDI score had significant influences. CONCLUSION: More patients returned to work at 6 weeks after CDA compared with ACDF, although there was no difference by 6 months. After 2 years, a nonsignificant trend toward higher employment rates in the arthroplasty group was evident, but this difference could not be validated due to the very high rate of loss of patients to the follow-up. LEVEL OF EVIDENCE: 2.

The Mobi-C® cervical disc and other devices for two-level disc replacement: overview of its safety and efficacy.

INTRODUCTION: Cervical disc arthroplasty (CDA) has become an acceptable alternative for anterior cervical discectomy and fusion (ACDF) for a significant patient population with cervical radiculopathy and/or myelopathy secondary to degenerative changes in the cervical spine. There are sufficient mid- and long-term data supporting performance and safety of one-level CDA. With the success of single-level cervical CDA, considerable interest exists about CDA use for multilevel cervical degenerative disc disease (DDD). This review analyzes the safety and efficacy of two-level CDA for treatment of symptomatic cervical DDD with focus on the Mobi-C® Cervical Disc. AREAS COVERED: This review summarizes previously published articles in a literature search using keywords: 'two-level-anterior cervical arthrodesis; two-level anterior cervical decompression and fusion (ACDF); two-level cervical disc arthroplasty (CDA); two-level cervical total disc replacement; two-level symptomatic degenerative disc disease (DDD); Mobi-C® disc'. EXPERT OPINION: Two-level CDA with the Mobi-C® device demonstrated equivalent, and in certain aspects, favorable outcomes compared to ACDF for treatment of symptomatic cervical 2-level degenerative disc disease (DDD) indicating a satisfactory safety and efficacy profile.

Review of long-term outcomes of disc arthroplasty for symptomatic single level cervical degenerative disc disease.

INTRODUCTION: Cervical disc arthroplasty (CDA) was developed as an alternative for anterior cervical discectomy and fusion (ACDF) for nerve root decompression. The rationale behind CDA was to help prevent adjacent segment degeneration which potentially may lead to additional surgery. Multiple randomized controlled trials have evaluated a myriad of disc arthroplasty devices over the past 10 years and provided data regarding clinical benefits and safety. Their long-term data, reporting results at 5-10 years, presents the opportunity to comment on the overall efficacy, safety and reported complications of these devices. This report reviews results of the Prestige, proDisc-C, Mobi-C Disc and various other arthroplasty devices and provides an overall report of the longest term available data and comparisons between devices. AREAS COVERED: This review summarizes previously published articles in a literature search using keywords: 'cervical disc arthroplasty', 'cervical total disc replacement', 'anterior cervical decompression and fusion', 'anterior cervical arthrodesis', 'symptomatic degenerative disc disease' and commercial names of devices. EXPERT COMMENTARY: CDA, with the devices reviewed, resulted in favorable outcomes in comparison to ACDF for the treatment of symptomatic cervical degenerative disc disease (DDD) taking in to account the long-term functional recovery, adverse events, development of adjacent segment degeneration and subsequent surgical interventions.

Uniplanar Versus Fixed Pedicle Screws in the Correction of Thoracic Kyphosis in the Treatment of Adolescent Idiopathic Scoliosis (AIS).

BACKGROUND: The aim of surgical treatment of scoliosis is to obtain fusion of the spinal column, balanced in the coronal and sagittal planes. Great success has been attained with coronal correction; however, the sagittal profile has received less attention, resulting in little correction of sagittal plane alignment. The purpose of this study was to compare uniplanar and fixed pedicle screws in the correction of the thoracic sagittal alignment in the treatment of adolescent idiopathic scoliosis (AIS). METHODS: The sagittal profile of 2 groups of patients undergoing posterior spinal fusion (PSF) for AIS was compared. One group had uniplanar screws (n=16) as bone anchors, and the second group had fixed screws (n=20). Consecutive patients with AIS treated by PSF during 2004 to 2006 with fixed screws; and those treated in 2008 with uniplanar screws were included in the study. Data included: patient demographics, medical conditions, curve type, Risser stage, coronal and sagittal curve magnitude, curve flexibility, osteotomies, fusion levels, type and location of instrumentation, curve magnitude at the initial postoperative visit and at final follow-up. ANOVA and χ testing was completed. A P<0.05 was considered significant. RESULTS: Both groups were comparable demographically, medically, in relation to the curve characteristics and the surgical treatment. Immediate postcorrection sagittal curvature measurements were greater using the uniplanar than fixed screws, 36 versus 26 degrees and was also statistically significant at final follow-up (P=0.006). There was no difference between groups with respect to coronal thoracic deformity. In the Lenke 1 and Lenke 2 curve population, similar results were found. CONCLUSIONS: In patients undergoing PSF for AIS, uniplanar screws achieved superior correction of the sagittal thoracic alignment than fixed screws. This advantage was maintained in the postoperative follow-up period. The ability of the uniplanar screws to adapt to variable sagittal orientation appears to contribute to better radiographic outcomes. LEVEL OF EVIDENCE: This is a level III respective review study conducted at a single center from a single, pediatric spine surgeon.

Chronic C1-C2 Rotatory Subluxation Reduced by C1 Lateral Mass Screws and C2 Translaminar Screws: A Case Report.

BACKGROUND: C1-C2 rotatory subluxation can result from a variety or etiologies. Pediatric patients are particularly susceptible to C1-C2 rotatory subluxation. If left untreated the condition is termed an atlantoaxial rotatory fixation (AARF) and chronic neck pain and deformity can result. Patients failing conservative treatment or those with recurrent or chronic rotatory subluxation may require halo treatment or surgical intervention. This illustrative case report is about a patient with chronic C1-C2 AARF who was treated with C1 lateral mass screws and C2 translaminar screws, a treatment that has not been addressed by this technique in a pediatric population. METHODS: This is a retrospective case review. RESULTS: After an unsuccessful attempt at reduction, an 11-year-old girl underwent surgery to treat her C1-C2 AARF. Through an all posterior approach, screws were placed bilaterally into the C1 lateral masses followed by the placement of C2 translaminar screws bilaterally. A small amount of distraction was applied through the screw construct to open up the C1-C2 articulation and the AARF was open reduced and fused. A detailed postoperative computed tomographic scan focused on the occiput C1-C2 joint confirmed the anatomical reduction of the joint complex. CONCLUSIONS: The patient had cosmetically pleasing relief of her torticollis and was doing well at 60 months after surgery. LEVEL OF EVIDENCE: Level IV.

Predisposing factors for dural tear in patients undergoing lumbar spine surgery.

OBJECT The purpose of this prospective cohort study was to identify risk factors for incidental durotomies in lumbar spine surgery. The authors hypothesized that the incidence of durotomy would be higher in cases involving multiple operations. METHODS The authors prospectively evaluated 523 patients who underwent lumbar and thoracolumbar spine surgery. They compared data on patients in whom a dural tear occurred and those in whom a dural tear did not occur. Data from patients in whom a dural tear occurred were compared with data from patients who did not experience durotomy. The data included basic demographic information, intraoperative data, and clinical information from a medical record review. RESULTS One hundred thirty-one patients underwent discectomy and 392 patients underwent laminectomy. Among the 131 patients who underwent discectomy 6 patients had a dural tear. Among the 392 patients who underwent discectomy 49 patients had dural tear. Patients with incidental durotomy were older (mean 65 ± 13 vs 60 ± 14 years of age; p = 0.044, t-test), and had longer surgery (146 ± 59 vs 110 ± 54 minutes; p = 0.025, t-test), compared with the patients without dural tear. The incidence of dural tear was more common in patients with a history of previous spine surgery (p < 0.001). CONCLUSIONS In patients who underwent lumbar and thoracolumbar spine surgery for degenerative problems, previous surgery and older age were found to be predisposing factors for dural tear.

Toward a better understanding of direct vertebral rotation for AIS surgery: development of a multisegmental biomechanical model and factors affecting correction.

BACKGROUND CONTEXT: The direct vertebral rotation (DVR) technique involves vertebral manipulation by the application of force in the transverse plane using a pedicle screw as the anchor point. The biomechanics of this technique has not been well studied, and the applied derotation force may affect cosmetic outcome and potential complications. PURPOSE: The purpose of the study was to develop an in vitro biomechanical model replicating DVR and examine the effects of screw placement, derotation direction, and segmental versus en bloc rotation on correction. STUDY DESIGN: This study is based on a cadaveric spine model examining the biomechanics of DVR. METHODS: Short three vertebral segments were dissected from thoracolumbar cadaveric spines (T5-L4). Each pedicle of the central vertebra received a unicortical, bicortical, or in-out-in screw. Unconstrained biomechanical tests were performed in an axial rotation (medial and lateral directions) mimicking DVR surgery. Nondestructive tests were performed examining peak force and rotational stiffness with/without a contralateral rod. A destructive failure test was performed on each pedicle screw with a contralateral rod connecting via the contralateral pedicle screw. Repeated-measures analysis of variance and post hoc Student t tests were used to detect significance with screw placement and loading direction as main factors. RESULTS: Without the contralateral rod, the rotation direction was significant (p=.004, medial stiffness more than lateral). With the contralateral rod, in-out-in placement demonstrated lower stiffness than unicortical or bicortical screws (p=.009), and the rotation direction was significant (p=.003, medial stiffness more than lateral). There was no interaction effect between main factors. Peak force with and without a contralateral rod resulted in a similar pattern of significance as stiffness. Destructive failure tests showed that the placement was significant (p<.02) with in-out-in resulting in lower stiffness than unicortical- and bicortical-placed screws. In-out-in (25±6 N) and unicortical (35±16 N) placements resulted in lower peak load (p<.001) than bicortical (48±17 N) screws. CONCLUSIONS: The biomechanical characteristics of DVR are dependent on the derotation direction and screw placement. Correction for adolescent idiopathic scoliosis can be attempted irrespective of the type of pedicle screw placement, more efficiently if performing derotation maneuvers en bloc on bicortical screws in the medial direction.

Tuberculosis of spine with neurological deficit in advanced pregnancy: a report of three cases.

BACKGROUND CONTEXT: Early decompression in spinal tuberculosis (TB) with complete paraplegia has a better prognosis in relation to the neurological recovery and deformity progression. Advanced pregnancy can complicate this picture in view of the various fetomaternal factors. The prevalent literature is inconclusive regarding the time and extent of surgical intervention. Delay in the surgical intervention may adversely affect the prognosis. PURPOSE: To emphasize the importance of early decompression in spinal TB complicated by neurological deficit in advanced pregnancy. STUDY DESIGN: A case report of three patients to analyze the surgical management of neurological deficit because of spinal TB in pregnancy. OUTCOME MEASURES: Neurological recovery, progression of deformity, healing of the TB lesion, and outcome of the pregnancy. METHODS: Three patients presented with spinal TB with neurological deficit complicating third trimester of pregnancy. The first patient was initially managed conservatively but was operated after a spontaneous abortion. The remaining two patients were managed by urgent Caesarean section followed by spinal decompression and fusion. RESULTS: The first patient who underwent delayed decompression showed good healing of the TB lesion but continued to have spastic paraparesis with kyphosis. This was later managed by repeat decompression and instrumented fusion, without neurological recovery. The other two patients treated by early decompression and fusion showed complete healing with neurological recovery. CONCLUSIONS: Early decompression and instrumented fusion in spinal TB, complicated by neurological deficit in advanced pregnancy, can give good results with respect to neurological recovery, healing of the lesion, and arrest of deformity progression. Neonatal prognosis depends on the fetal maturity. Antitubercular therapy is an essential component of the management; it poses little hazard of inducing congenital anomalies, but possibility of maternal drug toxicity should be considered.

Spinal instability in ankylosing spondylitis.

BACKGROUND: Unstable spinal lesions in patients with ankylosing spondylitis are common and have a high incidence of associated neurological deficit. The evolution and presentation of these lesions is unclear and the management strategies can be confusing. We present retrospective analysis of the cases of ankylosing spondylitis developing spinal instability either due to spondylodiscitis or fractures for mechanisms of injury, presentations, management strategies and outcome. MATERIALS AND METHODS: In a retrospective analysis of 16 cases of ankylosing spondylitis, treated surgically for unstable spinal lesions over a period of 12 years (1995-2007); 87.5% (n=14) patients had low energy (no obvious/trivial) trauma while 12.5% (n=2) patients sustained high energy trauma. The most common presentation was pain associated with neurological deficit. The surgical indications included neurological deficit, chronic pain due to instability and progressive deformity. All patients were treated surgically with anterior surgery in 18.8% (n=3) patients, posterior in 56.2% (n=9) patients and combined approach in 25% (n=4) patients. Instrumented fusion was carried out in 87.5% (n=14) patients. Average surgical duration was 3.84 (Range 2-7.5) hours, blood loss 765.6 (+/- 472.5) ml and follow-up 54.5 (Range 18-54) months. The patients were evaluated for pain score, Frankel neurological grading, deformity progression and radiological fusion. One patient died of medical complications a week following surgery. RESULTS: Intra-operative adverse events like dural tears and inadequate deformity correction occurred in 18.7% (n=3) patients (Cases 6, 7 and 8) which could be managed conservatively. There was a significant improvement in the Visual analogue score for pain from a pre-surgical median of 8 to post-surgical median of 2 (P=0.001), while the neurological status improved in 90% (n=9) patients among those with preoperative neurological deficit who could be followed-up (n =10). Frankel grading improved from C to E in 31.25% (n=5) patients, D to E in 12.5% (n=2) and B to D in 12.5% (n=2), while it remained unchanged in the remaining - E in 31.25% (n=5), B in 6.25% (n=1) and D in 6.25% (n=1). Fusion occurred in 11 (68.7%) patients, while 12.5% (n=2) had pseudoarthrosis and 12.5% (n=2) patients had evidence of inadequate fusion. 68.7% (n=11) patients regained their pre-injury functional status, with no spine related complaints and 25% (n=4) patients had complaints like chronic back pain and deformity progression. In one patient (6.2%) who died of medical complications a week following surgery, the neurological function remained unchanged (Frankel grade D). Persistent back pain attributed to inadequate fusion/ pseudoarthrosis could be managed conservatively in 12.5% (n=2) patients. Progression of deformity and pain secondary to pseudoarthrosis, requiring revision surgery was noted in one patient (6.2%). One patient (6.2%) had no neurological recovery following the surgery and continued to have nonfunctional neurological status. CONCLUSION: In ankylosing spondylitis, the diagnosis of unstable spinal lesions needs high index of suspicion and extensive radiological evaluation Surgery is indicated if neurological deficit, two/three column injury, significant pain and progressive deformity are present. Long segment instrumentation and fusion is ideal.

Occipito-atlanto-axial osteoarthritis: a cross sectional clinico-radiological prevalence study in high risk and general population.

STUDY DESIGN: A cross-sectional clinico-radiologic evaluation of occipito-atlantoaxial (OC1C2) region of 2 population groups. OBJECTIVE: Determine the prevalence of OC1C2 osteoarthritis in porters involved in carrying loads on the head and general male population. Describe its clinico-radiologic manifestations. SUMMARY OF THE BACKGROUND DATA: In addition to age, head loading is a known cause of degeneration affecting the occipito-cervical region. The impact of head loading in the population aged between third and sixth decade is unknown. Head loading is a common custom in the developing countries. MATERIAL AND METHODS: Study group (n = 107) included randomly selected male porters from railway stations who underwent computed tomography (CT) study of the OC1C2 region, plain radiographs of the cervical spine and detailed clinical examination. Control group (n = 107) included randomly selected male patients undergoing CT scan study for diseases of paranasal sinuses with coincidental screening of OC1C2 region along with clinical assessment. The data were analyzed using SPSS 15 software. RESULT: Mean age for study group was 32.6 years and controls was 34.6 years (P = 0.156). In the study group, duration of occupational exposure was 10.9 (+/-8.7) years; 81.3% porters being symptomatic with an age of 33.4 (+/-9.6) years. Radiologic prevalence of OC1C2 osteoarthritis in study group was 91.6% and in control group was 6.8%; age of affected individuals was 33.4 (+/-9.3) and 47.9 (+/-8.0) years, respectively. Most common complaint was suboccipital neck pain (69.7%); while the CT finding was decreased joint space with sclerosis and irregularity of the margins (81.3%). No statistically significant association was found between presence of radiologic changes and symptoms. Age, duration of occupational exposure and its relationship with various clinico-radiologic manifestations was studied. CONCLUSION: This condition has significant prevalence in porters, beginning at an early age. Diagnosis is based on the clinico-radiologic presentation. CT is the investigation of choice. Resultant functional limitations make early identification of this condition imperative.