Posterior Cervical Fusion
Posterior cervical fusion means operating the neck from the back and doing a fusion surgery so as to stabilize the neck. This surgery is usually performed in conjunction with laminectomy. Laminectomy means removing the bone and the tissue from the back of the spinal cord in the neck. Laminectomy is performed to remove the pressure from the spinal cord and possibly nerve roots if needed.
Laminectomy in itself is bound to fail by causing instability of the neck. Posterior cervical fusion provides stability to the neck after laminectomy, to avoid late failures, which can be disastrous.
The surgery of posterior cervical fusion and laminectomy is usually performed on a long segment covering almost 50-70% of the neck as compared to the surgery from the front, which includes anterior cervical discectomy and fusion (ACDF) and Total disc replacement (TDR) and is done at shorter levels of 1 to 3 levels only.
Posterior cervical fusion and laminectomy is usually performed over 4 to 6 segments depending on the need. As it is a fusion surgery, it also leads to more stiffness, but the patients who usually need this surgery are already stiff and have pathology or disease, which can be properly taken care of from the surgery from the back of the neck only. If the disease is localized and can be taken care of from the front, then surgery from the front is preferred.
The most common and widely used indication for laminectomy and posterior cervical fusion is cervical spondylotic myelopathy (CSM). CSM is defined as arthritic changes on the neck due to the ossification of the ligaments or disc disease, which causes compression of the spinal cord leading to changes in the neurological status of a patient.
CSM usually presents with weakness in the upper extremity only or in all four extremities. It may be associated with tingling and numbness. It may also be associated with gait problems due to imbalance and bowel and bladder issues. Patients with such a presentation may either stay stable or deteriorate.
Patients who deteriorate over time can only be treated by surgical options in an attempt to stop the progression and allow recovery. If the surgery involves multiple levels then surgery from the back is a good option to take care of the disease.
Multilevel compression of the spinal cord due to arthritic changes is the most common indication for this surgery. Patients with a small canal, which can be there since birth is at a higher risk of this disease process. For patients who are deteriorating neurological status, surgery is the only good option to halt the progression and possibly allow recovery of the neurological status.
Posterior laminectomy and posterior cervical fusion are done from the back of the neck. It is a major spine surgery, which requires meticulous preparation and skills and instrumentation of the highest quality to carry it out. A thorough discussion with the patient is done before the surgery with regards to expectations and results. All relevant clearances from all the needed specialties as well as the anesthesia team are taken.
The patient is taken to the operating room where general anesthesia is used. A tube is passed into the windpipe to control respiration and breathing. The anesthesia team puts the patient onto multiple monitoring systems. Neurologic monitoring is also used to check the patient’s neurological status during the surgery. The neurological monitoring checks sensory as well as motor functions.
Once everything is in place, the patient is turned onto his belly on the operating table. The head of the patient is usually fixed to the table by the use of tongs (pins). Once a good position is managed, the shoulders are strapped. X-ray in the operating room is used to check the position of the neck as well as the levels.
A straight midline incision is used from the base of the head along the back of the neck. By meticulous dissection and control of bleeding, the bone on the back of the spine is reached and the muscles are separated from the bone. The back part of the vertebrae of the neck is removed meticulously with the use of bur at all the levels required.
Once the bone is removed, the spinal cord is exposed. Further, necessary cleaning up or decompression of the spinal cord is done with the use of precision instruments, this procedure is done at multiple levels as needed.
Now, the screws are planned into the outer part of the vertebral body (lateral mass). The screws are planned at each level, which needs to be fixed so as to prevent the instability from laminectomy and allow fusion. Once the screws are put in place, rods are put to fix the screws on either side to each other.
If the patient has radicular symptoms then a foraminotomy can also be performed at the same time. If there is a deformity then further excision of the facet joints allows the correction of the deformity before the rod fixation. Once the implants are in place and tightened, final pictures are checked with the x-ray.
The facet joints which are of the vertebrae, which are to be fused are decorticated with the use of a bur and bone graft is put over the area of the facets to allow fusion. The central part of the spine and the spinal cord are checked to be thoroughly decompressed. The wound is thoroughly washed and drained. Blood oozings are controlled.
Closure of the wound is done in layers. Vancomycin antibiotic powder is used, which allows the prevention of infection. The skin is closed and the patient is turned onto the back. A collar may be put after the surgery over the dressing. The tube is usually removed by the anesthesia after the surgery. Occasionally, the patient may need to go to ICU with or without the tube for a day for critical monitoring.
Patients after laminectomy and posterior cervical fusion heal gradually over time. These patients may need to go to the rehab depending on their neurological status before and after the surgery. The recovery in the neurological status can take some time. The recovery may not be complete as the recovery of the spinal cord and nerves is unpredictable. The surgery helps in stopping further deterioration of the neurological status, and at the same time optimizing the conditions for the spinal cord to recover as much as it can.
Laminectomy and posterior cervical surgery is major surgery and has risks and complications. A surgery can lead to further deterioration of neurological status due to injury to the spinal cord and nerve roots. Weakness of muscles of one or both shoulders can happen after surgery. There is a risk of bleeding and need for blood transfusion. There is rare risk of injury to the vertebral artery.
Other risks include dural tear, implant failure, failure of fusion, incomplete recovery, failure of the adjacent segment. Other risks include infection and wound dehiscence, which is more common in surgeries from the back of the neck than the front.
Laminectomy and posterior cervical fusion surgery is done in carefully selected patients can help prevent further deterioration of neurological symptoms as well as help in the recovery of the neurological deficits that have already happened. This surgery has higher risks and complications than the surgery from the front, but in carefully selected patients can be helpful and critical.
Overall, the risks and complications are more from surgery from the back than the front of the neck. For the same reason, surgeries on the front of the neck are preferred, but in patients who have multilevel involvement and compression involved from the back are not good candidates for surgery from the front and need to be treated from the back.