This study will comprehensively evaluate the outcomes and endpoints of these two different FDA-approved artificial disc implants used to treat cervical spondylotic myelopathy and/or radiculopathy today: Biomet Zimmer Mobi-C and Nuvasive Simplify. Both implants are structurally different with the Nuvasive Simplify implementing a three-piece design with two endplates and a semi-constrained mobile core while the Biomet Zimmer Mobi-C implements an unconstrained three piece design. Subjects will be age-matched and randomly assigned to either implant with informed consent. All subjects will undergo a variety of assessments that evaluate neck disability, quality of life, pain, physiological outcome (radiographic assessments), and neck range-of motion before and after their procedure. One baseline testing will be conducted along with three post-operation visits (three months, six months, and one year) in accordance to standard follow-up procedure. Thus, the duration of participation in the study will be approximately one and a half years.
Patient is skeletally mature and between 18 to 60 years of age
Experiences cervical spondylotic myelopathy and/or radiculopathy typically caused by disc herniation or degenerative disc disease at a single level between C3 to C7
Is unresponsive to at least six weeks of non-surgical conservative care
Has the intention of undergoing cervical arthroplasty for their chief complaint
Patient has had prior cervical spine surgery
Has more than two diseased levels requiring surgery
Has a known allergy to a metal alloy or polyethylene
Is morbidly obese
Subjects must be experiencing cervical spondylotic myelopathy and/or radiculopathy typically caused by disc herniation or degenerative disc disease at a single level between C3 to C7 after being unresponsive to at least six weeks of non-surgical conservative care. This study is for patients who have the intention of undergoing cervical arthroplasty and have already been recommended to do so by a doctor.
Cohort
Prospective
Cervical arthroplasty
Procedure/SurgeryA joint replacement procedure administered by inserting an artificial disc between the vertebrae to replace a natural spinal disc after it has been removed.
Semi-Constrained Nuvasive Simplify
DeviceThis weight-bearing implant consisting of PEEK (polyetheretherketone) endplates and one semi-constrained, fully articulating, mobile zirconia toughened alumina (ZTA) ceramic core will be administered by cervical arthroplasty into the specified single-level cervical region.
Unconstrained Biomet Zimmer Mobi-C
DeviceThis unconstrained, three-piece implant will be administered by cervical arthroplasty into the specified single-level cervical region.
Cervical range of motion assessments with VICON
Will measure flexion/extension, lateral bending, rotation, protraction/retraction in degrees. The outcome will reflect any improvement in physiological neck range of motion be patients undergoing this procedure.
Questionnaires on neck disability
Will administer surveys on neck disability index, work status, pain intensity worksheet, treatment satisfaction form, and the SF-12 v2 Health Survey. The 12-item Short Form Survey version 2 (SF-12 v2) is a general health questionnaire that reports two summary scores - a mental component score (MCS-12) and a physical component score (PCS-12). The scores are reported as Z-scores (difference compared to the population average, measured in standard deviations) with the US population average PCS-12 and MCS-12 being both 50 points. Scores range from 0 to 100, with higher scores indicating better physical and mental health functioning. Overall, these assessments will help to gauge overall quality of life, pain, and patient satisfaction with their treatment.
Neurological examination: gait assessment
Will take place as part of standard care for this operation. A gait assessment will be performed according to Nurick's Classification. Nurick's classification is graded from 0-5 or normal, with a number grade denoting some neurological deficit. 0 is least severe, with the patient showing root signs and symptoms with no evidence of spinal cord involvement. Grade 5 is most severe, described as chair bound or bedridden.
Neurological examination: foraminal compression test
The foraminal compression test is a physical examination technique which reduces the opening of the foramen which may demonstrate if there is pressure upon the exiting spinal nerve. The test is done to detect spinal nerve root involvement, a herniated disc, bulging disc, or foraminal stenosis. The scoring is binary, either negative or positive, to test for any pain the patient experiences during the exam.
Radiographic assessments: disc height
Will take place as part of standard care for this operation. Anterior and Posterior Disc Height will be measured from neutral lateral radiographs. Anterior (Posterior) Disc Height is defined as the distance between the anterior-inferior (posterior-inferior) corner of the superior vertebra, and the corresponding corner of the inferior vertebra. This distance is measured perpendicular to the superior endplate of the inferior vertebra and will be reported in units of millimeters. Average Disc Height is calculated as the simple average of the Anterior and Posterior Disc Heights.
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