Mobi-C^® Cervical Disc

Device Description

The Mobi-C^® Cervical Disc Prosthesis (Mobi-C^®) is a single use device for cervical intervertebral disc replacement at one level or two contiguous levels from C3 to C7 designed to maintain/restore segmental motion and disc height. The components of the Mobi-C^® include a cobalt, chromium, molybdenum (CoCrMo per ISO 5832-12) alloy superior spinal plate, an inferior CoCrMo spinal plate, and an ultra-high molecular weight polyethylene (UHMWPE per ISO 5834-2) mobile insert. The inner contact surfaces of the superior and inferior spinal plates are spherical and flat, respectively. This allows for fully congruent contact surfaces between the spinal plates and mobile insert. The two lateral stops of the inferior plate are designed to control and limit the mobility of the mobile insert. The spinal plates, both superior and inferior, feature two rows of teeth which are designed to aid in initial and long term fixation and stability. The teeth are designed to sink into the bone to facilitate endplate fixation and do not require any bone removal or chiseling prior to insertion.  A titanium (per ASTM F1580) and hydroxyapatite (per ISO 13779) plasma spray coating is applied to the bony interface surfaces of the superior and inferior spinal plates.

Indications for Use

The Mobi-C^® Cervical Disc Prosthesis is indicated in skeletally mature patients for reconstruction of the disc from C3-C7 following discectomy at one level or two contiguous levels for intractable radiculopathy (arm pain and/or a neurological deficit) with or without neck pain, or myelopathy due to abnormality localized to the level of the disc space and at least one of the following conditions confirmed by radiographic imaging (CT, MRI, X-rays): herniated nucleus pulposus, spondylosis (defined by the presence of osteophytes), and/or visible loss of disc height compared to adjacent levels.  The Mobi-C^® Cervical Disc Prosthesis is implanted using an anterior approach. Patients should have failed at least 6 weeks of conservative treatment or demonstrated progressive signs or symptoms despite nonoperative treatment prior to implantation of the Mobi-C® Cervical Disc Prosthesis.

Contraindications

The Mobi-C^® Cervical Disc Prosthesis should not be implanted in patients with the following conditions:

• Acute or chronic infection, systemic or at the operative site;
• Known allergy or sensitivity to the implant materials (cobalt, chromium, molybdenum, titanium, hydroxyapatite, or polyethylene);
• Compromised vertebral bodies at the index level due to previous trauma to the cervical spine or to significant cervical anatomical deformity or disease (e.g., ankylosing spondylitis, rheumatoid arthritis);
• Marked cervical instability on resting lateral or flexion/extension radiographs demonstrated by translation greater than 3.5mm, and/or > 11° angular difference to that of either adjacent level;
• Osteoporosis or osteopenia defined as DEXA bone mineral density T-score < -1.5;
• Severe facet joint disease or degeneration.

Warnings

• Mobi-C^® should only be used by surgeons who are experienced with anterior cervical spinal procedures and have undergone hands-on training in the use of this device. Only surgeons who are familiar with the implant components, instruments, procedure, clinical applications, biomechanics, adverse events, and risks associated with the Mobi-C^® should use this device. A lack of adequate experience and/or training may lead to a higher incidence of adverse events, including neurological complications.
• Correct selection of the appropriate implant size is extremely important to assure the placement and function of the device. Information regarding proper implant size selection, implant site preparation, and the use of the instrumentation before, during, and after Mobi-C^® surgery is provided in the Mobi-C^® Surgical Technique Manual and the Mobi-C^® Instrument System Instructions for Use. Users are advised to read and understand the surgical technique manual and instructions for use prior to surgery.
• Due to the proximity of vascular and neurological structures to the implantation site, there are risks of serious or fatal hemorrhage and risks of neurological damage with the use of the device. Care must be taken to identify and protect these structures.
• Heterotopic Ossification (HO) is a potential complication associated with artificial cervical discs and could lead to reduced cervical motion. However, the presence of HO has not been correlated with adverse clinical outcomes involving the Mobi-C^® Cervical Disc Prosthesis in the G050212 clinical trial.

Precautions

The safety and effectiveness of this device has not been established in patients with the following conditions: 

• Skeletally immature patients, pediatric or adolescent children (<21 years old), or those over the age of 67;
• Prior cervical spine surgery, including prior surgery at the index level;
• More than two diseased or immobile cervical spine levels requiring surgical intervention;
• Disc height less than 3mm measured from the center of the disc in a neutral position and disc height less than 20% of the anterior-posterior width of the inferior vertebral body;
• Significant kyphotic deformity or significant reversal of lordosis;
• Active malignancy;
• Paget’s disease, osteomalacia, or other metabolic bone disease;
• Taking medications known to potentially interfere with bone/soft tissue healing (e.g. steroids);
• Pregnancy;
• Diabetes mellitus requiring daily insulin management;
• Clinically extreme obesity (class III) as defined by the NIH Clinical Guidelines Body Mass Index (i.e. BMI >40);
• Neck or arm pain of unknown etiology;
• Systemic disease including AIDS, HIV, and Hepatitis;
• Intractable radiculopathy or myelopathy due to pathology at more than two levels and/or pathology not localized to the level of the disc space;
• Prior fusion at an adjacent vertebral level;
• Neck pain alone;
• Rheumatoid arthritis or other autoimmune disease;
• Neuromuscular disorders such as muscular dystrophy, spinal muscular atrophy, or amyotrophic lateral sclerosis;
• Acute mental illness or substance abuse.

Pre-operative

• Patient selection is extremely important. In selecting patients for total disc replacement, the following factors can be of importance to the success of the procedure: the patient’s occupation or activity level, prior injury or other ongoing illness, alcoholism, or drug abuse; and certain degenerative diseases (e.g., degenerative scoliosis or ankylosing spondylitis) that may be so advanced at the time of implantation that the expected useful life of the device is substantially decreased.
• In order to minimize the risk of periprosthetic vertebral fractures, surgeons must consider all co-morbidities, past and present medications, previous treatments, etc. A screening questionnaire for osteopenia or osteoporosis, SCORE (Simple Calculated Osteoporosis Risk Estimation), may be used to screen patients to determine if a DEXA bone mineral density measurement is necessary. If DEXA is performed, the patient should be excluded from receiving the device if the DEXA bone density measured T score is < -1.5, as the patient may be osteoporotic or osteopenic.
• The patient should be informed of the potential adverse effects (risks/complications) contained in the insert (see ADVERSE EVENTS).
• Preoperative planning may be used to estimate the required implant size and to assure that the appropriate range of sizes is available for surgery. The procedure should not take place if the appropriate range of sizes will not be available.
• Examine all instruments prior to surgery for wear or damage. Instruments which have been used excessively may be more likely to break. Replace any worn or damaged instruments.

Intra-operative

• Use aseptic technique when removing the Mobi-C® from the innermost packaging. Carefully inspect each component and its packaging for any signs of damage, including damage to the sterile barrier. Do not use Mobi-C^® implants if the packaging is damaged or the implant shows signs of damage.
• Use care when handling the Mobi-C^® to ensure that it does not come in contact with objects that could damage the implant. Damaged implants are no longer functionally reliable. Visual inspection of the prosthesis assembly is recommended prior to implanting the device. If any part of the assembly appears damaged or not fully assembled, do not use.
• To prevent unnecessary damage to the bearing surfaces, ensure that tissue or other debris is not trapped within the device.
• The Mobi-C^® should not be used with components or instruments of spinal systems from other manufacturers. See the surgical technique for step by step instructions.
• Surgical implants must never be re-used or reimplanted. Even though the device appears undamaged, it may have small defects and internal stress patterns that may lead to early breakage.
• Perform a complete discectomy of the disc space between the unci and up to the posterior ligament. Take care to release the foramen bilaterally. It is important to remove all anterior and posterior osteophytes on the superior and inferior vertebral endplates. Liberally cover bleeding with bone wax. To prevent weakening of the endplates, use of a burr is discouraged during endplate preparation. Use the Caspar Retractor as needed to maintain or modify distraction. Ensure proper alignment and placement of device components as misalignment may cause excessive wear and/or early failure of the device.

Post-operative

• Patients should be instructed in postoperative care procedures and should be advised of the importance of adhering to these procedures for successful treatment with the device including the avoidance of heavy lifting, repetitive bending, and prolonged or strenuous activity initially and for a period of weeks to months depending on the individual patient’s progress and the stability and functioning of the implant.
• Note to Physician: Although the physician is the learned intermediary between the company and the patient, the important medical information given in this document should be conveyed to the patient.