Reproducibility of 3D pH-weighted chemical exchange saturation transfer contrast in the healthy cervical spinal cord.

Spinal cord ischemia and hypoxia can be caused by compression, injury, and vascular alterations. Measuring ischemia and hypoxia directly in the spinal cord noninvasively remains challenging. Ischemia and hypoxia alter tissue pH, providing a physiologic parameter that may be more directly related to tissue viability. Chemical exchange saturation transfer (CEST) is an MRI contrast mechanism that can be made sensitive to pH. More specifically, amine/amide concentration independent detection (AACID) is a recently developed endogenous CEST contrast that has demonstrated sensitivity to intracellular pH at 9.4 T. The goal of this study was to evaluate the reproducibility of AACID CEST measurements at different levels of the healthy cervical spinal cord at 3.0 T incorporating B1 correction. Using a 3.0 T MRI scanner, two 3D CEST scans (saturation pulse train followed by a 3D snapshot gradient-echo readout) were performed on 12 healthy subjects approximately 10 days apart, with the CEST volume centered at the C4 level for all subjects. Scan-rescan reproducibility was evaluated by examining between and within-subject coefficients of variation (CVs) and absolute AACID value differences. The C4 level of the spinal cord demonstrated the lowest within-subject CVs (4.1%-4.3%), between-subject CVs (5.6%-6.3%), and absolute AACID percent difference (5.8-6.1%). The B1 correction scheme significantly improved reproducibility (adjusted p-value = 0.002) compared with the noncorrected data, suggesting that implementing B1 corrections in the spinal cord is beneficial. It was concluded that pH-weighted AACID measurements, incorporating B1-inhomogeneity correction, were reproducible within subjects along the healthy cervical spinal cord and that optimal image quality was achieved at the center of the 3D CEST volume.

Does design matter? Cervical disc replacements under review.

The present article reviews the design rationale of currently available cervical disc replacements. Recent prospective randomized control trials comparing cervical disc replacement and anterior fusion have demonstrated safety as well as equal or superior clinical results. Increasingly, more devices are becoming available on the market. Understanding design rationale will provide context for the surgeon to optimize decision making for the most appropriate prosthesis. Cervical arthroplasty is a technique that is undergoing rapid design refinement and development. Further improvements in device design will enable patient-specific device selection. Understanding the design rationale and complication profile of each device will improve clinical and radiographic outcomes.

Cervical Spondylotic Myelopathy: Metabolite Changes in the Primary Motor Cortex after Surgery.

Purpose To characterize longitudinal metabolite alterations in the motor cortex of patients with cervical spondylotic myelopathy (CSM) by using proton magnetic resonance (MR) spectroscopy and to evaluate white matter integrity with diffusion-tensor imaging in patients who are recovering neurologic function after decompression surgery. Materials and Methods Informed written consent was obtained for all procedures and the study was approved by Western University's Health Sciences Research Ethics Board. Twenty-eight patients with CSM and 10 healthy control subjects were prospectively recruited and underwent two separate 3-T MR imaging examinations 6 months apart. Patients with CSM underwent surgery after the first examination. N-acetylaspartate (NAA), an indicator of neuronal mitochondrial function, normalized to creatine (Cr) levels were measured from the motor cortex contralateral to the greater functional deficit side in the patient group and on both sides in the control group. Fractional anisotropy and mean diffusivity were measured by means of diffusion-tensor imaging in the white matter adjacent to the motor and sensory cortices of the hand and the entire cerebral white matter. Clinical data were analyzed by using Student t tests. Results In patients with CSM, NAA normalized to Cr (NAA/Cr) levels were significantly lower 6 months after surgery (1.48 ± 0.08; P < .03) compared with preoperative levels (1.73 ± 0.09), despite significant improvement in clinical questionnaire scores. Fractional anisotropy and mean diffusivity were the same (P > .05) between the patient and control groups in all measured regions at all time points. Conclusion NAA/Cr levels decreased in the motor cortex in patients with CSM 6 months after successful surgery. Intact white matter integrity with decreased NAA/Cr levels suggests that mitochondrial metabolic dysfunction persists after surgery. © RSNA, 2016 Online supplemental material is available for this article.

Zinc oxide tetrapods inhibit herpes simplex virus infection of cultured corneas.

PURPOSE: Infection of the human cornea by herpes simplex virus type-1 (HSV-1) can cause significant vision loss. The purpose of this study was to develop an ex vivo model to visualize viral growth and spread in the cornea. The model was also used to analyze cytokine production and study the antiviral effects of zinc oxide tetrapods. METHODS: A ß-galactosidase-expressing recombinant virus, HSV-1(KOS)tk12, was used to demonstrate the ability of the virus to enter and develop blue plaques on human corneal epithelial (HCE) cells and corneal tissues. Freshly obtained porcine corneas were cultured and then scratched before infection with HSV-1(KOS)tk12. The blue plaques on the corneas were imaged using a stereomicroscope. Western blot analysis for HSV-1 proteins was performed to verify HSV-1 infection of the cornea. Using the ex vivo model, zinc oxide tetrapods were tested for their anti-HSV-1 potential, and a cytokine profile was developed to assess the effects of the treatment. RESULTS: Cultured corneas and the use of ß-galactosidase-expressing HSV-1(KOS)tk12 virus can provide an attractive ex vivo model to visualize and study HSV-1 entry and spread of the infection in tissues. We found that unlike cultured HCE cells, which demonstrated nearly 100% infectivity, HSV-1 infection of the cultured cornea was more restrictive and took longer to develop. We also found that the zinc oxide tetrapod-shaped nano- and microstructures inhibited HSV infection of the cultured cells, as well as the cultured corneas. The cytokine profile of the infected samples was consistent with previous studies of HSV-1 corneal infection. CONCLUSIONS: The ability to visualize HSV-1 growth and spread in corneal tissues can provide new details about HSV-1 infection of the cornea and the efficacy of new cornea-specific antiviral drug candidates. The ex vivo model also demonstrates antiviral effects of zinc oxide tetrapods and adequately portrays the drug delivery issues that cornea-specific treatments face.

Effects of Oxygen Concentrations on Postresuscitation Myocardial Oxidative Stress and Myocardial Function in a Rat Model of Cardiopulmonary Resuscitation.

OBJECTIVE: Lipid peroxidation induced by free-radical species plays a prominent role in myocardial injury following ischemia and reperfusion. However, there is a lack of data in different oxygen concentrations on myocardial lipid peroxidation during the early phase of reperfusion. In this study, we investigated whether ventilation with medium or normal concentration of oxygen would decrease the severity of myocardial lipid peroxidation and postresuscitation myocardial dysfunction. DESIGN: Prospective, randomized, controlled experimental study. SETTING: University-affiliated animal research institution. SUBJECTS: Sixty-three healthy male Sprague-Dawley rats. INTERVENTIONS: Animals were randomized into three groups: 1) 100% group, 2) 50% group, and 3) 21% group. Ventricular fibrillation was induced and untreated for 8 minutes, and defibrillation was attempted after 8 minutes of cardiopulmonary resuscitation. Ventilation with 100%, 50%, or 21% oxygen was initiated in all groups during cardiopulmonary resuscitation and 1 hour following the return of spontaneous circulation. Normoxic ventilation was maintained thereafter. MEASUREMENTS AND MAIN RESULTS: Myocardial function, including ejection fraction and myocardial performance index, were measured at baseline, 4, or 72 hours after resuscitation. Blood samples were drawn at baseline, 15 minutes, 1, 4, or 72 hours after resuscitation for the measurements of blood gas or biomarkers. Significantly better myocardial function and longer duration of survival were observed in the 50% group. Compared with the 21% and 100% groups, a mild hyperoxia and greater oxygen extraction with lower 8-iso-prostaglandin F2α were observed in the 50% group. Pearson correlation analysis confirmed that 8-iso-prostaglandin F2α was positively correlated with myocardial performance index at 4 hours postresuscitation. CONCLUSIONS: In a rat model of cardiac arrest and resuscitation, ventilation with 50% inspired oxygen during early postischemic reperfusion phase contributed to a decreased lipid peroxidation and a better myocardial function and duration of survival.

Reduced Endotracheal Tube Cuff Pressure to Assess Dysphagia After Anterior Cervical Spine Surgery.

STUDY DESIGN: This was a prospective, randomized control pilot study. OBJECTIVE: The aim of this study was to determine whether continuous monitoring and adjustment of the endotracheal tube cuff pressure (ETTCP) to 15 mm Hg during ACSS would alter the incidence of postoperative dysphagia. SUMMARY OF BACKGROUND DATA: Postoperative dysphagia is a recognized potential complication of anterior cervical spine surgery (ACSS). Recent findings on preventive measures suggest that certain intraoperative practices may minimize this complication. METHODS: Fifty patients undergoing ACSS, arthroplasty, or fusion, completed routine lateral cervical preoperative plain films and questionnaires [Dysphagia Disability Index (DDI), Bazaz-Yoo Dysphagia Score (BYDS), and Short Form (36) Health Survey]. Patients were randomized into 2 groups: treatment group with ETTCP maintained at 15 mm Hg and control group with cuff pressure monitored without manipulation. Radiographs and questionnaires were obtained at 24 hours, 6 weeks, and 3 and 6 months postsurgery to assess soft tissue thickness and rates of dysphagia. RESULTS: There were no significant differences between the groups in the soft tissue thickness or questionnaire scores at any timepoint (P>0.05). Within-group analysis revealed treatment and control groups had a significantly higher 24-hour postoperative soft tissue thickness and questionnaire scores compared with follow-up measurements (P<0.05). In the pooled group (n=50), the 24-hour postoperative DDI, BYDS, and soft tissue thickness were significantly higher compared with all other timepoints (P<0.01). DDI scores ≥10 related to dysphagia were in 59% of patients at 24 hours, 35% at 6 weeks, 24% at 3 months, and 18% at 6 months. CONCLUSIONS: This study suggests decreased ETTCP has no effect on the prevalence of dysphagia. The incidence of dysphagia decreases over time and normalizes by 6 months postsurgery.

The Impact of Neuroanesthesia Fellowship Training and Anesthesiologist-Surgeon Dyad Volume on Patient Outcomes in Adult Spine Surgery: A Population-Based Study.

INTRODUCTION: Extensive research has explored the impact of surgeons' characteristics on patient outcomes; however, the influence of anesthesiologists remains understudied. We performed a population-based retrospective cohort study to investigate the impact of anesthesiologists' characteristics on in-hospital morbidity after spine surgery. METHODS: Adult patients who underwent spine surgery at the London Health Science Centre, Ontario, Canada between January 1, 2010 and June 30, 2023 were included in this study. Data was extracted from the local administrative database. Five anesthesiologists' characteristics (neuroanesthesia fellowship and residency training backgrounds, surgeon familiarity, annual case volume, and sex) were examined as primary exposures. The primary outcome was composite in-hospital morbidity, encompassing 141 complications. Multivariable logistic regression was performed to assess the association between anesthesiologists' characteristics and postoperative morbidity with adjustment of patients' sex, Charlson Comorbidities Index, surgical complexity, and surgeon characteristics. RESULTS: A total of 7692 spine surgeries were included in the analysis. Being a neuroanesthesia fellowship-trained anesthesiologist and high anesthesiologist-surgeon annual dyad volume were associated with reduction in in-hospital comorbidity; adjusted odds ratio (95% CI) of 0.58 (0.49-0.69; P<0.001) and 0.93 (0.91-0.95; P<0.001), respectively. Conversely, anesthesiologist annual case volume, characteristics of residency training and anesthesiologist sex showed only nuanced associations with outcomes. CONCLUSIONS: Neuroanesthesia fellowship training and high surgeon-anesthesiologist dyad familiarity was associated with a reduction in in-hospital morbidity following spine surgery. These findings underscore the superiority of structured fellowship education over case exposure experience alone, advocate for dedicated neuroanesthesia teams with high surgeon-anesthesiologist dyad volume and recognize neuroanesthesia as a crucial subspecialty in spine surgery.

Characterizing mJOA-defined post-surgical recovery patterns in patients with degenerative cervical myelopathy.

Background: Degenerative cervical myelopathy is a spinal disorder resulting in progressive cord compression and neurological deficits that are assessed using the modified Japanese Orthopedic Association (mJOA) questionnaire. It is difficult to predict which patients will recover neurological function after surgery, making it challenging for clinicians to set postoperative patient expectations. In this study, we used mJOA subscores to identify patterns of recovery and recovery timelines in patients with moderate and severe myelopathy. Methods: Fifty-three myelopathy patients were enrolled and completed the mJOA questionnaire both pre-surgery, and six weeks and six months post-surgery. Pearson chi-square tests were performed to assess relationships of both recovery patterns and recovery timelines with severity of disease. Results: Moderate myelopathy patients were significantly more likely than severe myelopathy patients to experience full recovery of upper extremity, lower extremity, and sensory domains. Disease severity did not significantly impact the timeline during which recovery occurs. Overall, >90% of patients experienced at least partial recovery by six months post surgery, 80% of which demonstrated it within the first six weeks. Conclusions: This study shows the more severe the disease experienced by myelopathy patients, the more likely they will be left with permanent disabilities despite surgery. Early identification and treatment are therefore necessary to prevent worsening quality of life and increased costs of functional dependence. The recovery timelines for each subscore are similar and provide new values to guide patient expectations in their potential post-operative recovery. The overall recovery timeline is more generalizable though potentially lacking the specificity patients seek.

Proton magnetic resonance spectroscopy of the motor cortex in cervical myelopathy.

Alterations in motor function in cervical myelopathy secondary to degenerative disease may be due to local effects of spinal compression or distal effects related to cortical reorganization. This prospective study characterizes differences in metabolite levels in the motor cortex, specifically N-acetylaspartate, creatine, choline, myo-inositol and glutamate plus glutamine, due to alterations in cortical function in patients with reversible spinal cord compression compared with healthy controls. We hypothesized that N-acetylaspartate/creatine levels would be decreased in the motor cortex of patients with cervical myelopathy due to reduced neuronal integrity/function and myo-inositol/creatine levels would be increased due to reactive gliosis. Twenty-four patients with cervical myelopathy and 11 healthy controls underwent proton-magnetic resonance spectroscopy on a 3.0 Tesla Siemens Magnetom Tim Trio MRI. Areas of activation from functional magnetic resonance imaging scans of a finger-tapping paradigm were used to localize a voxel on the side of greater motor deficit in the myelopathy group (n = 10 on right side and n = 14 on left side of the brain) and on each side of the motor cortex in controls. Neurological function was measured with the Neck Disability Index, modified Japanese Orthopaedic Association and American Spinal Injury Association questionnaires. Metabolite levels were measured relative to total creatine within the voxel of interest. No metabolite differences were detected between the right side and left side of the motor cortex in controls. The myelopathy group had significantly decreased neurological function compared with the control group (Neck Disability Index: P < 0.001 and modified Japanese Orthopaedic Association: P < 0.001). There was a significant decrease in the N-acetylaspartate/creatine metabolite ratio in the motor cortex of the myelopathy group (1.21 ± 0.07) compared with the right (1.37 ± 0.03; P = 0.01) and left (1.38 ± 0.03; P = 0.007) motor cortex in controls suggesting neuronal damage or dysfunction distal to the lesion in the spine. No difference was observed in levels of myo-inositol/creatine. Thus, cortical levels of N-acetylaspartate/creatine may be a meaningful biomarker in cervical myelopathy, indicative of neuronal damage or dysfunction.

The importance of measuring prolactin prior to surgical management of a pituitary lesion: An illustrative case.

The characterization of sellar and suprasellar lesions is reliant on patient presentation, medical imaging, and hormone profiling. Prolactinomas are the most common type of functional pituitary adenomas, accounting for up to 57%. Importantly, prolactinomas can present without clear symptoms and with doubtful or even normal imaging. A 41-year-old male patient was referred to neurosurgery for consideration for resection of a sellar lesion, as initial CT imaging suggested a large meningioma. Subsequent MRI of the sella favored macroadenoma, meningioma, and craniopharyngioma as the top differential considerations. These conditions all indicate a diagnosis that would require surgical management. Clinical evaluation of this patient did not elicit any obvious clinical features suggestive of hyperprolactinemia. Fortunately, we obtained a full hormone panel which revealed a significantly elevated prolactin level of 17,390 µg/L. Based on this elevated prolactin level, we diagnosed a pituitary giant prolactinoma. Treatment with a dopamine agonist therapy was initiated and the response confirmed this diagnosis. This case demonstrates the importance of obtaining a prolactin level prior to surgical management of a sellar lesion. Had a prolactin level not been obtained, this patient would have undergone surgical resection based on both the imaging and clinical judgment.

ProDisc-C: an in vivo kinematic study.

STUDY DESIGN: A prospective study of 22 patients with single-level cervical spondylosis. OBJECTIVE: To quantify the changes in the biomechanics of the cervical spine after the insertion of a ProDisc-C (Synthes Spine, Paoli, PA) artificial disc. SUMMARY OF BACKGROUND DATA: Cervical arthroplasty is designed to maintain cervical motion of the functional spinal unit (FSU) after cervical discectomy. The impact of the ProDisc-C on in vivo kinematics and sagittal alignment requires further assessment. METHODS: Flexion/extension lateral radiographs of the cervical spine were prospectively collected and reviewed in 22 patients preoperatively and after the placement of ProDisc-C. Disc height (DH), FSU angle, range of motion (ROM), and center of rotation (COR) were calculated at each time point using validated, computer-assisted methods. Preoperative values were compared with the postoperative values using paired student t tests. RESULTS: Mean follow-up time was 11.0 months (SD, 2.4 mo). At the surgical level, the ProDisc-C produced increased segmental ROM (P = 0.03), an anterior shift of 1.1 mm in COR X (P = 0.004), and increased DH both anteriorly (P < 0.0001) and posteriorly (P < 0.0001). At the inferior adjacent level, anterior DH decreased (P < 0.05) and posterior DH increased (P = 0.02) after surgery. The FSU angle at the surgical level increased (P < 0.0001), but the inferior adjacent-level FSU angle decreased (P = 0.002). No significant changes were observed at the superior adjacent level. CONCLUSIONS: The ProDisc-C increased segmental ROM and shifted the COR anteriorly at the surgical level. DH increased at the surgical level. The surgical level became more lordotic, whereas the inferior adjacent level became more kyphotic after ProDisc-C implantation.

Chondroblastoma of the knee in a teenager.

Chondroblastoma is an uncommon osseous neoplasm that accounts for less than 1% of all bone tumors. Characteristically it arises in the epiphysis or apophysis of long bones in young patients and may extend into the metaphysis. A sixteen-year-old male presents with a 1-year history of left knee pain associated with joint stiffness and interfering with performing daily activities. Radiographic and contrast enhanced magnetic resonance imaging favored the diagnosis of chondroblastoma. This was then confirmed histologically. The clinical signs and symptoms of Chondroblastoma are usually nonspecific, pain is most often moderate and can be revealed as a result of a trauma. The definitive diagnosis is mainly pathological due to the lack of specificity of radiological findings consistent with the presented case.

Pfeiffer syndrome in an adult with previous surgical correction: A case report of CT findings.

Pfeiffer syndrome, affecting roughly 1 in 100,000 individuals is characterized by acrocephalosyndactyly - the premature closure of skull sutures (craniosynostosis). These acrocephalosyndactyly syndromes which are often sporadic de novo but also autosomal dominant in inheritance can be characterized by the fact that they often involve FGFR and TWIST genes. In the presented case, a 27-year old male level three trauma admission displayed skull abnormalities on physical examination that history taking confirmed was the result of pediatric surgically corrected Pfeiffer syndrome. Noncontrast brain CT as part of his trauma work-up revealed characteristic Pfeiffer syndrome imaging pattern of midface hypoplasia, nonvisualization of coronal and sagittal sutures, and a degree of obstructive hydrocephalus. Pfeiffer syndrome requires extensive pediatric surgery often with poor adult follow up. The case presented provides good visualization of characteristic skull abnormalities in a surgically corrected adult. By virtue of imaging an adult, this provides readers with a unique look at the long-term viability and the body's resulting physiological adaptations of the extensive mandatory pediatric surgery these patients undergo.

Spinal cord compression is associated with brain plasticity in degenerative cervical myelopathy.

The impact of spinal cord compression severity on brain plasticity and prognostic determinates is not yet fully understood. We investigated the association between the severity of spinal cord compression in patients with degenerative cervical myelopathy, a progressive disease of the spine, and functional plasticity in the motor cortex and subcortical areas using functional magnetic resonance imaging. A 3.0 T MRI scanner was used to acquire functional images of the brain in 23 degenerative cervical myelopathy patients. Patients were instructed to perform a structured finger-tapping task to activate the motor cortex to assess the extent of cortical activation. T2-weighted images of the brain and spine were also acquired to quantify the severity of spinal cord compression. The observed blood oxygen level-dependent signal increase in the contralateral primary motor cortex was associated with spinal cord compression severity when patients tapped with their left hand (r = 0.49, P = 0.02) and right hand (r = 0.56, P = 0.005). The volume of activation in the contralateral primary motor cortex also increased with spinal cord compression severity when patients tapped with their left hand (r = 0.55, P = 0.006) and right hand (r = 0.45, P = 0.03). The subcortical areas (cerebellum, putamen, caudate and thalamus) also demonstrated a significant relationship with compression severity. It was concluded that degenerative cervical myelopathy patients with severe spinal cord compression recruit larger regions of the motor cortex to perform finger-tapping tasks, which suggests that this adaptation is a compensatory response to neurological injury and tissue damage in the spinal cord.

Use of tissue glues in endoscopic pituitary surgery: a cost comparison.

BACKGROUND: Post-operative cerebrospinal fluid (CSF) leaks are a common complication of endoscopic pituitary surgery and account for a significant proportion of hospital costs associated with this procedure. Tisseel® is a tissue glue commonly used as an adjunct in dural repair but is not optimal for this purpose. DuraSeal® has several properties advantageous for dural repair but is not widely accepted in Canada partly due to its increased cost. OBJECTIVE: A cost analysis of DuraSeal® versus Tisseel® in endoscopic pituitary surgery. METHODS: A cost analysis was performed based on typical endoscopic pituitary surgery cases performed at our tertiary care institution. Operating room, hospital admission, and surgical sealant costs were obtained directly while estimates of patient recovery time and post-operative CSF leak rates were based on consensus values reported in the literature. Outcomes were reported for various possible clinical scenarios of sealant use. RESULTS: In a model where surgical sealant is employed only in high-risk cases, use of DuraSeal® allows for a yearly cost savings of at least $4486.72. If surgical sealant is used in all cases, regular use of DuraSeal® versus Tisseel® either marginally reduces yearly costs or increases them by a maximum of $7619.25, depending on the case volume and estimated post-operative CSF leak rate. CONCLUSION: In most clinical scenarios, use of DuraSeal® in endoscopic pituitary surgery may reduce overall yearly hospital costs compared to Tisseel®.

Conservative management of pituitary macroadenoma contacting the optic apparatus.

OBJECTIVES: To describe the tumor characteristics and visual function in conservatively managed patients with non-functioning pituitary macroadenoma (NFMA) that contacted/compressed the visual pathway. DESIGN: Retrospective case-series. SETTING: Tertiary-care academic institution. PARTICIPANTS: Six patients with diagnosis of NFMA. MAIN OUTCOME: Visual function and radiological characteristics of the optic apparatus and pituitary tumor. RESULTS: All patients had radiological evidence of optic apparatus compression but only one had visual field defect at the initial presentation. While two of the six patients developed visual field changes during followup (41±34.8 months), the patient with visual field defect at the time of diagnosis improved to normal vision. CONCLUSIONS: Select NFMAs that contact the optic apparatus, without visual dysfunction, may be managed with close ophthalmological and radiographic monitoring, depending on tumor and imaging characteristics. This may be of particular relevance in patients considered to have a high peri-operative risk, such as advanced age or significant co-morbidities.

Biomechanics of a posture-controlling cervical artificial disc: mechanical, in vitro, and finite-element analysis.

Different methods have been described by numerous investigators for experimentally assessing the kinematics of cervical artificial discs. However, in addition to understanding how artificial discs affect range of motion, it is also clinically relevant to understand how artificial discs affect segmental posture. The purpose of this paper is to describe novel considerations and methods for experimentally assessing cervical spine postural control in the laboratory. These methods, which include mechanical testing, cadaveric testing, and computer modeling studies, are applied in comparing postural biomechanics of a novel postural control arthroplasty (PCA) device versus standard ball-and-socket (BS) and ball-in-trough (BT) arthroplasty devices. The overall body of evidence from this group of tests supports the conclusion that the PCA device does control posture to a particular lordotic position, whereas BS and BT devices move freely through their ranges of motion.

Effect of arthroplasty design on cervical spine kinematics: analysis of the Bryan Disc, ProDisc-C, and Synergy disc.

OBJECT: Cervical total disc replacement has emerged as a surgical option to preserve motion and potentially avoid adjacent-segment disease after anterior cervical discectomy and fusion. Recently, much attention has been directed at the ability of a given device to maintain and/or restore normal segmental alignment. Nonphysiological disc and segmental angulation could result in increased stresses transmitted to the facet joints and posterior elements, conflicting with the essence of arthroplasty and potentially leading to adjacent-segment disease. The goal of this study was to contrast device alignment and segmental kinematics provided by 3 different cervical disc prostheses. METHODS: Sixty patients were retrospectively analyzed and divided into 3 groups receiving the Bryan, ProDisc-C, or Synergy disc. Only single-level arthroplasty cases were included in the study. Lateral dynamic radiographs of the cervical spine were analyzed using quantitative motion analysis software (Medical Metrics, Inc.) to analyze the kinematics at the index level both preoperatively and postoperatively. Several parameters were noted, including range of motion, disc angles, shell angles, anterior and posterior disc heights, translation, and center of rotation. Preoperative and postoperative data were compared using the Student t-test with a significance level of p < 0.05. RESULTS: Postoperatively, all 3 disc groups maintained adequate range of motion at the implanted level. With respect to the shell angles, the Synergy disc demonstrated the least variability, maintaining 6 degrees lordotic configuration between the device endplates. In the Bryan disc group, significant shell kyphosis developed postoperatively (p < 0.0001). Both ProDisc-C and Synergy discs significantly increased anterior and posterior disc heights (p < 0.0001). The Bryan and Synergy discs maintained the natural center of rotation, whereas significant anterior shift occurred with ProDisc-C. CONCLUSIONS: The goal for motion preservation at the implanted level was achieved using all 3 devices. The Synergy disc was unique in its ability to alter device angulation by 6 degrees. The Bryan disc demonstrated device endplate kyphosis. Both the Synergy disc and ProDisc-C increased disc space height.