A herniated disc in the cervical spine is most often the result of the normal aging process called degenerative disc disease. It can also be due to a more acute event such as direct trauma to the cervical spine. The disc herniates posteriorly into the spinal canal, putting pressure on the spinal cord or the exiting nerve roots that supply sensation and motor control to the arms and hands. Symptoms of a cervical herniated disc man include pain in the neck, shoulders, arms, and hands, weakness of the arms or legs, numbness and tingling in the upper extremities, difficulty walking or imbalance. Non-surgical treatments for cervical disc herniations include a short course of oral steroids, physical therapy, chiropractic care, steroid injections, and pain medication. When these modalities fail to improve symptoms over time, surgical intervention is considered.
Anterior cervical discectomy and fusion (ACDF) has been the standard surgical treatment for degenerative conditions of the cervical spine, including degenerative disc disease and cervical spondylotic myelopathy, for almost half a century. Considerable research has demonstrated the efficacy of the ACDF procedure with plate fusion for the treatment of cervical disc herniations with successful resolution of preoperative symptoms. ACDF is a well-accepted treatment for patients experiencing neck and arm symptoms due to degenerative disc disease of the cervical spine. This procedure has long been performed by making an incision in the front of the neck, removing the diseased disc, and inserting an interbody device in its place to maintain intervertebral disc height and encourage fusion across the vertebral bodies. The implant is frequently held in place with a titanium plate anchored by screws. Studies have shown that the addition of an anterior plate with screws to an interbody cage or spacer provides enhanced stability and increased fusion rates.
Although successful in achieving fusion, anterior plating is not without complications. Dysphagia is the most common postoperative complication, and it has been linked to the anterior prominence associated with plate and screw constructs and the adhesions that form in response to the plate. The risk of complications with the ACDF surgery increases substantially with a multi-level discectomy and plate fusion, as a larger incision is necessary to adequately dissect the cervical spine and place the plate across multiple vertebral bodies. This increases the potential for greater blood loss during the procedure as well as postoperative wound infection. By eliminating the need for a cervical plate, a smaller incision can be used, allowing for less manipulation of the airway, vocal cords, esophagus, and vascular structures. This more minimally invasive approach allows for a decrease in the rate of complications and shortens the length of hospital stay.
In an effort to reduce the potential complications associated with these plate constructs, surgeons in the Department of Neurological Surgery have adopted a novel technique using a zero-profile interbody fixation device that eliminates the need for an anterior plate after a discectomy procedure. The STALIF-CTM, developed by Centinel Spine, is a radiolucent cervical integrated interbody fusion device constructed of polyether-ether-ketone (PEEK) with three integrated cancellous screws designed to provide lag compression between the adjacent vertebral bodies and confer anterior column fixation. The design avoids the need for any additional internal fixation devices while providing the segmental rigidity necessary for cervical spinal fusion.
This zero-profile device is contained entirely within the disc space and does not protrude past the anterior wall of the vertebral body as does an anterior cervical plate. This minimizes soft tissue irritation and contact with the esophagus and vocal cords. The risk of future complications in adjacent levels of the cervical spine is also theoretically minimized, as it has been shown that cervical plates placed near an adjacent level may lead to bone formation and degeneration of that adjacent disc. This device is biomechanically similar to a cage and plate fusion, providing the patient with immediate mechanical stability while reducing the morbidity associated with plate fusion.
In order to carefully evaluate this new technique, a prospective investigation was performed on all patients who underwent implantation of the zero-profile STALIF-C device instead of a cervical plate fixation for both single level as well as multi-level cervical discectomy surgery starting back in January 2011. The primary indication for surgery was symptoms of radiculopathy and/or myelopathy due to a herniated disc that had failed non-surgical measures of treatment. The mean age of patients undergoing surgery was 54 years old, with ages ranging from 28 to 69 years. Cervical fusion was assessed at three months using antero-posterior and lateral plain radiographs. Self-reported outcomes were measured using patient questionnaires, including the SF-12, the Neck Disability Index, EuroQol-5D, and a visual analog scale for pain, that were completed preoperatively, and at three and six months following surgery.
Our study found that there was a statistically significant improvement in preoperative symptoms for the entire cohort (p=0.001). There were no cases of persistent dysphagia, vocal cord injury, or pseudoarthrosis (i.e. failure of fusion) in all patients who have so far had the device implanted. Perhaps most importantly, there was no statistical difference in outcomes between patients undergoing multi-level discectomy surgery (in some cases up to four levels) and those patients who underwent surgery for a single level alone. This study has supported our adoption of zero-profile devices over plate fixation for all patients undergoing routine cervical discectomy surgery.