Unison®-C Anterior Cervical Fixation System
The anterior cervical standalone procedure was developed based on the desire for a less invasive option that also reduces surgical time. When compared to competitive systems, the Unison-C Anterior Cervical Fixation System better meets these requirements through simplicity of implant design and technique efficiencies. The system offers an interbody implant with integrated screw fixation and incorporates an easily deployable screw backout mechanism. Our interbody offering allows surgeons to treat the widest range of patients while the versatility of the instrumentation is designed to accommodate their preferred technique.
- Lordotic implant
- Multiple footprints
- Available in heights from 6 to 10mm
- Large graft space
- Highly visible X-ray markers
- Made with PEEK-OPTIMA® from lnvibio® Biomaterial Solutions
Implants are supplied sterile. Instruments and screws are supplied nonsterile. For sterilization instructions, please reference the package insert.
The Unison-C Anterior Cervical Fixation system is indicated for stand-alone anterior cervical interbody fusion procedures in skeletally mature patients with degenerative disc disease (DDD) at one level from C2 to T1. Degenerative disc disease is defined as neck pain of discogenic origin with degeneration of the disc confirmed by history and radiographic studies. The system is intended to be used with autograft and/or allogenic bone graft comprised of cancellous and/or corticocancellous bone graft to facilitate fusion, and is implanted via an anterior approach. Implants must be used with two of the provided bone screws. This system is to be used in patients who have had six weeks of non-operative treatment.
These implants are contraindicated and should not be used for, including but not limited to, patients with the following:
- Active systemic infection or an active infection at the operative site
- A demonstrated allergy or sensitivity to polyether ether ketone, titanium alloy, tantalum
- Disease conditions which have been shown to be safely and predictably managed without the use of internal fixation
- Severe osteoporosis may increase the occurrence of subsidence, migration, or other implant failure
- Any condition that precludes the possibility of fusion, e.g., kidney dialysis, metabolic disorders or osteopenia
- Conditions that may place excessive stresses on bones and the implants, including but not limited to morbid obesity, or other degenerative diseases
- Foreign body sensitivity
- Whose activity, mental capacity, mental illness, alcoholism, drug abuse, occupation, or lifestyle may interfere with their ability to follow post-operative restrictions and who may place undue stress on the implant(s) during bony healing. These patients may be at a higher risk of implant fatigue, fracture, or dislocation
- Inadequate bone stock to support the implant
- Poor prognosis for good wound healing (e.g., decubitus ulcer, end-stage diabetes, severe protein deficiency and/or malnutrition)
- Use in the posterior elements (pedicles) of the cervical, thoracic, or lumbar vertebrae
- Where attempted correction exceeds the limits of physiological conditions
The same medical/ surgical conditions or complications that apply to any surgical procedure may also occur during or following implantation of this implant system. The surgeon is responsible for informing the patient of the potential risks associated with treatment, including complications and adverse reactions. The surgeon may need to perform additional surgery to address any complications or adverse reactions, which may or may not be implant related.
Potential risks identified with the use of this implant system, which may require additional surgery, include: implant component fracture, loss of fixation, pseudarthrosis (non-union), fracture of the vertebra, neurological injury, and vascular or visceral injury.
No implant system can withstand the forces of sudden dynamic loads such as falls or other accidents.
Mixing metals can cause corrosion. There are many forms of corrosion damage and several of these occur on metals surgically implanted in humans. General or uniform corrosion is present on all implanted metals and alloys. The rate of corrosive attack on metal implants is usually very low due to the presence of passive surface films. Dissimilar metals in contact, such as titanium and stainless steel, accelerates the corrosion process of stainless steel and more rapid attack occurs. The presence of corrosion compounds released into the body system will also increase. Internal fixation implants, such as rods, hooks, wires, etc. which come into contact with other metal objects, must be made from like or compatible metals. Components of other systems should not be used with this system.
Prior to use the surgeon must become familiar with the implant system and the surgical procedure. Use surgical instrumentation, accessories, and surgical technique guide provided with this implant system. The implantation of these implants should be performed only by experienced spinal surgeons with specific training in the use of this implant system because this is a technically demanding procedure presenting a risk of serious injury to the patient.
Correct handling of the implant is extremely important. Notches or scratches put in the implant during the course of surgery may also contribute to breakage. Alterations will produce internal stresses which may lead to eventual breakage of the implant. An explanted implant should never be re-implanted. Even though the implant appears undamaged, it may have small defects and internal stress patterns which may lead to early breakage.
Instruments are available for the implant system to aid in the accurate implantation or removal of internal fixation devices. Intraoperative fracture or breaking of instruments may occur. Instruments are subject to damage during use as well as long-term potentially damaging effects such as wear. Damage may result in significant risks to safety and/or inability to function as intended.
Instruments, which have experienced extensive use or excessive force, are susceptible to fracture. Instruments should be regularly inspected for wear and defects.
If instruments are damaged or broken during use, metal fragments can be viewed by radiographic assessment. It is the surgeon’s responsibility to carefully consider the risks and benefits of retrieving the fragments.
If the fragment is retained in the patient, it is recommended that the surgeon advise the patient of specific information regarding the fragment material, including size and location and the potential risks associated with the retained fragment.
Surgical instruments must be used only for the implant systems for which they are designed. Use of other manufacturer instruments can involve unevaluated risks for the implant and instrument, thereby potentially endangering the patient, user, or third party.
Implants can break when subjected to the increased loading associated with delayed union or non-union. Spinal implants are load sharing implants used to obtain an alignment until normal healing occurs. If healing is delayed or does not occur, the implant may eventually break due to fatigue. The degree or success of union, loads produced by weight bearing, and activity levels will, among other conditions, dictate the longevity of the implant.
MRI Safety Information
The implants are manufactured using non-ferromagnetic materials. These implants have not been tested for safety and compatibility in the MR environment. These implants have not been tested for heating, migration, or image artifact in the MR environment. The safety of these implants in the MR environment is unknown. Scanning a patient who has these implants may result in patient injury.
General Instructions for Use
It is important to read and understand the following instructions prior to clinical use. Improper preparation technique may adversely affect the success of the surgical procedure.
- All users are expected to read the instructions for use that accompany all devices being utilized with these implants.
- Implants and instruments should be stored in their original packaging in a dry environment, away from aggressive or oily chemicals
- Do not re-sterilize the implants in this implant system.
- Inspect the product, including all packaging and labeling materials carefully:
- Do not use past expiration date specified on the product label
- Do not use if the implant or packaging is damaged
- Do not use if there are discrepancies in label information
- Promptly report all product defects and patient adverse events to the manufacturer (see Product Complaints section).
The patient must be made aware of the limitations of the implant prior to consenting to surgery. The patient must be made aware that physical activity and full weight bearing have been implicated in fracture. The patient should understand that an implant is not as strong as normal, healthy bone and will fracture if excessive demands are placed on it in the absence of complete bone healing.
An active, debilitated, or demented patient who cannot properly use weight-supporting devices may be particularly at risk during postoperative rehabilitation.
Complications and adverse reactions have been reported with the use of similar spinal systems. These adverse effects, including the possibility of death, should be discussed with the patient prior to surgery. Possible neurological operative/postoperative complications/adverse reactions that may require medical or surgical intervention include:
- Paralysis, complete or incomplete. Delayed onset has occurred even when evoked potential was unaffected during surgery.
- Dural tear leading to cerebrospinal fluid fistula or pseudo meningocele.
- Other spinal cord injuries not otherwise described due to positioning of the implant.
- Laminar erosion.
- Epidural bleeding.
- Abnormal sensations.
Possible implant postoperative complications/adverse reactions that may require medical or surgical intervention include:
- Loosening, bending, breaking, disassembly, and/or migration of the components
- Collapse of a fracture and/or fusion site.
- Implant failure.
- Corrosion at the screw/locking mechanism interface contributing to breakage, and/or pseudarthrosis.
- Discomfort or pain, soft tissue erosion, or protrusion due to prominent implanted hardware.
- Attachment device pullout, especially with osteoporotic bone.
- Implant or graft extrusion through the skin.
- Postural deformities, pain, skin breakdown, or residual neural compression due to kyphosis or lordosis occurring at the top of the segment being instrumented.
- Bone loss or fracture due to stress shielding.
- Foreign body reaction to the implant including tumor formation, autoimmune disease, metallosis, and/or scarring.
- Non-union or pseudarthrosis.
- Cessation of growth at the fusion site.
- Discitis, arachnoiditis, and/or other types of inflammation.
Possible general or local postoperative complications/adverse reactions that may require medical or surgical intervention include:
- Deep vein thrombosis, thrombophlebitis, and/or pulmonary embolism that may be fatal; may be due to patient position and/or length of surgical procedure
- Decubitus ulcer
- Wound infection, deep or superficial, which may require implant removal and/or other medical interventions
- Wound dehiscence, delayed wound healing, or hematoma
- Pain, possibly severe in nature
- Urinary tract infection
- Blood vessel damage and/or blood loss or hemorrhage
- Fracture(s) of the bone
- Gastrointestinal, urological, and/or reproductive system compromise including sterility, impotency, and/or loss of consortium
- Bone graft donor site pain
- Inability to resume activities of normal daily living
When inserting the implant, care should be taken to avoid using excessive force which has the potential to cause damage to the implant or surrounding tissue.
- When preparing the disc space, care should be taken to ensure an appropriate amount of bone is removed; excessive removal of bone has the potential to cause subsidence while failing to remove enough bone has the potential to cause poor fusion.
- During screw insertion, care should be taken to avoid bone screw stripping which has the potential to cause an unstable screw construct.
- When inserting the implant, ensure a tight fit between the inserter and implant. Release distraction prior to drilling to prevent shifting.
- During distraction of the disc space, care should be taken to prevent over-distraction or under-distraction which has the potential to cause irreversible damage to the patient or an unstable implant construct.
- If existing hardware is present, compatibility between the distraction pin and the existing hardware should be verified prior to use. When the distraction pin is used with existing hardware, extreme care should be taken to prevent damage to existing hardware.
- It is important to be aware of the overall stability of the closure and use as many devices as necessary to achieve adequate fixation based on a surgeon’s assessment for each patient.
Intervertebral body implant:
- Ensure adequate intervertebral body implant position is achieved prior to final screw fixation.
- The screwdriver which has been designed for a particular system of screws must always be used to be sure that proper screwdriver/screw head connection is achieved.
- Incorrect alignment or fit of the screwdriver to the screw head may increase the risk of damage to the implant or screwdriver.
- Screws must be fully seated to verify their connection to the intervertebral body implant; unseated screws may increase the risk of screw back-out or compromise their intended function.
Screw Locking Mechanism:
- After the Screws are fully seated and implant has been verified to be in the proper position the Locking Mechanism is to be turned 90° for coverage of both Screws to minimize the potential for Screw back-out.
The surgeon should provide clear directions, warnings and must obtain verification of patient understanding for patient postoperative compliance. Postoperative care and the patient’s ability and willingness to follow instructions are extremely important aspects of successful bone healing. The patient is to be advised of the need for regular postoperative follow-up examination as long as the implant remains implanted. It is extremely important that the physician provides clear directions and warnings and obtains the utmost compliance from the patient postoperatively:
- Partial or non-weight bearing may be recommended or required to achieve firm bone union. Patients with senility, mental illness, alcoholism, or drug abuse may be at higher risk of implant failure since these patients may ignore instructions and activity restrictions. If appropriate, restrict patient’s mobility at the fusion region, and instruct the patient in the use of external supports and braces that are intended to immobilize the site of the fracture. Provide the patient with load bearing restrictions.
- If appropriate, restrict patient’s mobility to allow bony union
- Warn patient against sudden changes in position, strenuous activity, or falls that may cause additional injury
- Warn patient against smoking, consuming alcohol, and/ or taking steroids, non-steroidal anti-inflammatory agents and aspirin or other drugs not prescribed by the physician and mechanical vibrations or shocks that may loosen the implants.
- Implant presence may cause pain, discomfort, abnormal sensations, and increased risk of infection. Instruct the patient to seek medical attention if sudden changes in appearance at the surgical site are noticed or if an unexplained increase in pain is experienced.
- The patient is to be advised that the implant is a temporary implant intended to stabilize / secure the bone fracture(s) and augment the process of healing after which time, if conditions are unfavorable, the implant may be removed.
See product specific surgical technique manual and package insert for complete instructions and labeling limitations.