Cervical adjacent segment disease: Risks and complications following cervical fusion
Ross A. Hauser, MD. Danielle R. Steilen-Matias, MMS, PA-C. Brian R. Hutcheson, DC.
Understanding Anterior Cervical Discectomy and Fusion surgery, risks and complications following surgery
Many people have great success with cervical fusion surgery. These are the people we do not see in our clinic. The people seeking our help and the people we see in our clinic did not have such great success with their surgery. They developed more neck pain, more neck instability, and bone spurs. The need for more fusion has been recommended to them as well.
Let’s look at the journey some patients take after cervical neck fusion.
“Delayed and progressively worsening neurological problems following multisegmental cervical spinal fusion.”
First, we are going to explore a March 2020 paper presented in the Journal of Craniovertebral Junction and Spine (1) by a group of neurosurgeons. The paper reports on adjacent-segment “central” or “axial” atlantoaxial instability and C2-C3 instability as the cause of delayed and progressively worsening neurological problems following multisegmental cervical spinal fusion.
In this paper, the neurosurgeons described the cases of three male patients. A 34 year-old man, a 56 year-old man, and 70 year-old man, all who had surgery for cervical spondylosis by multilevel C3-C6 cervical interbody fusion some six to eleven years earlier. After an initial improvement for few years, the patients observed relatively rapid clinical deterioration. When admitted, all three patients were severely quadriparetic (they had severe weakness and function problems in both arms and legs) and were brought to the hospital in a wheelchair (they could not walk.)
In all three men, central atlantoaxial instability was diagnosed. More surgery was required The patients underwent atlantoaxial and C2-C3 fixation, on average 21 months after the new surgery the patients were able to walk independently again.
This paper concludes with an understanding of how this happened to these three men and how it happens to other patients
“The general understanding is that neurological symptoms are a result of direct neural compression (the nerves are getting pinched or impinged) or deformation. Recent studies have identified that rather than compression, neurological symptoms are secondary to instability-related subtle and repeated micro-injuries to neural structures. There could be instability of the spinal segments even when the bones are in alignment on dynamic imaging. Our recent classification identifies atlantoaxial instability even in the absence of any bone mal-alignment or direct neural or dural compression by odontoid process (spinal cord compression of the C2).”
Here are the learning points of this paper concerning cervical spine instability caused by cervical fusion and the resulting adjacent segment instability it can cause:
- Research is showing that “rather than compression, neurological symptoms are secondary to instability-related subtle and repeated micro-injuries to neural structures.” The damage that instability is causing can be on the micro-level, invisible to MRI or other imaging devices.
- In other words, following the fusion surgery, constant micro-tearing is happening. A systemic weakening of the adjacent segment in the cervical spine continues, slowly, deliberately and destructively.
- This slow and deliberate destruction will continue until the patient displays symptoms requiring further medical care. In this article, we hope to show how further medical care is the avoidance of more fusion surgery.
What is the evidence a patient has Atlantoaxial Instability? A past C2-C3 Fusion causing problems at C3-C7
Another paper presented in the March 2020 edition of the Journal of craniovertebral junction and spine (2) by the same group of neurosurgeons looked at patients who had symptoms related to cervical myelopathy and had a previous C2-C3 fusion and the presence of single or multiple level nerve compression of the subaxial (C3-C7 levels) cervical spinal cord attributed to “degenerative” spine.
In this study, the researchers examined seven adult males were analyzed who had long-standing symptoms of progressive cervical myelopathy and where imaging showed the presence of C2-3 fusion, no cord compression related to odontoid process (at C2), and evidence of single or multiple level lower cervical cord compression conventionally attributed to spinal degeneration. Conclusion: The presence of C2-C3 fusion is an indication of atlantoaxial instability and suggests the need for atlantoaxial stabilization (more fusion). Effects on the subaxial spine and spinal cord are secondary events and may not be surgically addressed. (If you fix the instability the pressure on the spinal cord can resolve itself. In our office we use non-surgical means to achieve this same treatment goal.)
This is a video case study of a patient that we are seeing in Caring Medical Florida
- This is a case study of a patient that we are seeing in Caring Medical Florida. This case will demonstrate two points:
- First, the reason to thoroughly consider the problems and challenges that you may face after cervical fusion surgery, and
- Second, what can we do for someone who already had the surgery?
The patient was in a car accident
- This patient is a middle-aged woman. Before the surgery, she led a very active, no pain, very full life. In 2017 she was involved in a car accident. She suffered cervical spine damage. At first, she tried the typical conservative care treatments which include anti-inflammatory medications, rest, physical therapy among other recommendations. Unfortunately, the patient did not respond to these treatments.
- The patient then went to see a surgeon who told her she needed a multi-level cervical spine fusion. In this case C5 – C7. The resulting fusion surgery digital motion x-ray image is shown at 0:40 of this video.
The rapid formation of bone spurs, adjacent segment disease, neck pain and cervical spine instability following surgery
- What this case demonstrates is how quickly bone spurs form and how quickly cervical spine instability and adjacent segment disease can take hold.
The vertebrae are sliding away from each other.
- At (1:15 of the video) Dr. Hauser demonstrates, the patient’s cervical instability at C3-C4. He does this by showing where the back of the C3 vertebrae and the back of the C4 vertebrae are lining up. There is a big misalignment between the two vertebrae.
- At 1:40 of the video, a bone spur at the adjacent level (C4-C5) has formed since the surgery. Demonstrated in the image below.
- This large bone spur formed within 2 years of the fusion surgery.
- At 2:15 of the video the patient is asked to bend her head forward so an assessment of her adjacent segment problems can be made. You can watch this in real-time because the Digital Motion X-Ray or DMX is just that – a motion X-ray.
- At 2:25 of the video the bone spur at C4-C5 is trying to stabilize the cervical spine.
- At 2:40 of the video Dr. Hauser discusses the severe cervical spine instability at the C3-C4 / C4 – C5 levels.
- At 2:50: the patient has anterolisthesis the upper vertebral body of C3 is slipping forward on C4, the upper vertebral body of C4 is slipping forward on C5.
- At 3:10: The slippage is demonstrated. Dr Hauser shows that between C1 and C5 the only thing that is holding this person’s upper cervical spine together above the fusion is the cervical spine ligaments of C2-C3 and they are now under stress and the upper cervical spine will likely require more fusion.
- At 4:20: Dr. Hauser describes the symptoms that the patient already has FOLLOWING the fusion surgery:
- Terrible headaches
- Terrible grinding, clicking, crunching in the neck.
- Swallowing difficulties
- Dr. Hauser summarizes that within 2 years of this fusion surgery, the patient is basically disabled and in need of more medical care with the desire to avoid further cervical spine fusion.
After the surgery: Problems you may not have anticipated
In the video above we present one case study of worsening problems after cervical spinal fusion. We see many patients with even worse situations and we are not alone in this. Here are post-fusion problems discussed in the medical literature.
Longer hospital stays because of blood pressure or weight:
- A March 2019 study (3) from the Ohio State University Wexner Medical Center suggests that if you suffer from metabolic syndrome, (obesity, high blood pressure, high cholesterol, diabetes), you will likely have to stay in the hospital a few days longer than usual.
Problems of constipation and stressful bowel movements
- You may have to deal with problems of constipation and stressful bowel movements that may put a strain on your neck.
Likely need narcotic pain medications
- You will likely need narcotic pain medications but will not be allowed to take NSAIDs such as Aspirin, Advil, Motrin, Aleve, Celebrex, etc., for fear that these medications will negatively impact the bone healing needed to complete the fusion. This recommendation can be anywhere from 3 to 6 months.
- Long-term alteration in your movements will be part of your recovery. This will include limited head movements, being able to lift common everyday objects over 5 pounds (like a gallon of milk or water), and regulating the amount of time you can sit.
Things you can’t do anymore
- You may not be able to drive a car, have sex, or exercise for some time. (Please see our article Patients report problems with sexual function after cervical spine surgery)
Cervical fusion after a shoulder arthroscopic surgery – unforeseen problems
Surgeons at Brown University wrote in the journal World Neurosurgery, (4) “Patients who undergo Anterior Cervical Discectomy and Fusion surgery with a prior shoulder arthroscopy have significantly greater revision rates, respiratory complications, and prolonged opioid use compared with patients without prior shoulder arthroscopy”
The need for painkillers after surgery is a dangerous need
Here is a disturbing study from July 2019 published in the journal Pain Research & Management.(5)
- “Worldwide, 80% of patients who undergo surgery receive opioid analgesics as the fundamental agent for pain relief. However, the irrational use of opioids leads to excessive drug dependence and drug abuse, resulting in an increased mortality rate. . . “
- “Sensory dysfunction is a common symptom of neuropathic pain. Nerve injury as a result of surgical manipulation is a leading cause of neuropathic pain after surgery.”
In the April 2019 issue of Lancet, (6) researchers at the University of Pennsylvania and Harvard wrote that “excessive prescribing of opioids for pain treatment after surgery has been recognized as an important concern for public health and a potential contributor to patterns of opioid misuse and related harm.”
As mentioned above, when your cervical vertebrae are fused to limit cervical instability and related symptoms, the force and energy in your neck movements are transferred to the vertebrae below the fusion and above the fusion. This is why people suffer from the same symptom at different locations a year to 3 years later. This is why many people are sent back to surgery to fuse more segments and why many get the symptoms back and they can even be worse. Let’s explore research from some of the leading universities and research hospitals that support these findings.
Patients undergoing ACDF commonly receive high-dose opioid prescriptions after surgery
In September 2019, researchers at The Johns Hopkins University and University of Virginia suggested in their research published in the Spine Journal (7) that “Patients undergoing ACDF commonly receive high-dose opioid prescriptions after surgery, and certain patient factors increase risk for chronic opioid use following ACDF. Interventions focusing on patients with these factors is essential to reduce long-term use of prescription opioids and postoperative care.” One of these factors was that some of these patients were already taking high dose opioid doses prior to surgery and continued to do so after surgery.
Within 10 years, 1 in 4 patients can be at risk of clinical adjacent segment disease.
These are some of the things we hear from patients and people who email us with questions who have to contemplate another procedure.
- My surgeon has recommended that I get another ACDF. This time the fusion will be below the first fusion I had at C5-C6. The new fusion will be at C7-C8. I am concerned that this will greatly limit my ability to move. I did not realize how much my neck movement would be after the first fusion.
- I had two ACDF fusions. My first surgery was more than 15 years ago at C6-C7. I just had C5-C6 fused. During the second surgery, they discovered a lot of scar tissue from the first. I am having a lot of pain in my neck, shoulders, and back. I am on painkillers now.
- I had a very successful C4-C5 fusion. My problem now is C3. I have degenerative disc disease with rupture. Now they want to expand my fusion to C3-C5.
Doctors at the University of Alberta noted in the Canadian Journal of Neurological Sciences: (8) “Cervical spine clinical adjacent segment pathology has a reported 3% annual incidence and 26% ten-year prevalence. Its pathophysiology remains controversial, whether due to mechanical stress of a fusion segment on adjacent levels or due to patient propensity to develop progressive degenerative change.”
Simply, within 10 years, 1 in 4 patients are at risk of clinical adjacent segment disease because of unnatural stress and destructive forces being placed on the cervical spine.
Some patients did not have a full understanding of what the fusion outcome will be.
In this video, Danielle R. Steilen-Matias, MMS, PA-C explains the challenges of adjacent segment disease
- We often get calls from patients who already had a cervical spine fusion or neck fusion surgery and are still suffering from the symptoms that sent them to the surgery in the first place, or, from patients for whom the cervical fusion helped initially, but the pain relief did not last and any relief was temporary.
- Some patients did not have a full understanding of what the fusion outcome will be. The segment that is fused does not move. Yet the patient still has to do their best to have normal neck movement. They have to move their head. They want to look down and look up and move their heads in a normal way.
- When you have a neck segment fused, the segments above and below the fusion have to take on the extra stress of providing as normal neck movement as possible and they are overworked and develop adjacent segment disease, a rapid deterioration of the cervical spine.
A case presented
- A female patient came in whom I treated. She had undergone two cervical fusions into the lower cervical spine. We did a DMX or digital motion x-ray which is explained and illustrated below to look at how unstable her neck was and we could see that the segment above her fusion was unnaturally moving all over the place. She had the fusion surgery 8 years ago, so this constant strain and degenerative wear and tear condition have been going on for some time. When she came in for her treatments, the symptoms she described were similar to the symptoms she had experienced 8 years prior that lead to her initial fusion surgery. A lot of neck pain, muscle tightness from muscle spasms, pain running down her arm from the vertebrae pinching on the cervical nerves.
- In her case, we determined that she would likely respond very favorably to Prolotherapy injections to stabilize the segment of her cervical spine instability.
Anterior cervical spondylosis surgery: a retrospective study with long-term follow-up found that fusion significantly and negatively alters the curve in the neck
In February 2018, orthopedic surgeons wrote in the Journal of Orthopaedic Surgery and Research (9) about their investigation of the incidence and causes of non-fusion segment disease, both adjacent and non-adjacent to a fused segment, after anterior cervical fusion.
Here are the results of their investigation:
- 171 patients who had an anterior cervical decompression and fusion were followed clinically for more than 5 years.
- Of the 171 patients reviewed, 16 patients had non-fusion segment disease (9.36%), of which 12 had adjacent segment disease and 4 had non-adjacent segment disease.
- Postoperative cervical lordosis in the non-fusion segment disease group was significantly smaller than that of the disease-free group
- The incidences of disc degeneration in unfused segments were more severe in the non-fusion segment disease group than in the disease-free group
- The major factor affecting non-fusion segment disease is postoperative cervical lordosis followed by cervical disc degeneration.
The conclusion: “The incidence of symptomatic non-fusion segment disease after anterior cervical arthrodesis has multifactorial causes. Postoperative cervical lordosis and disc degeneration in non-fusion segments were major factors in the incidence of non-fusion segment disease.”
The second cervical spine fusion makes the cervical lordosis even worse
Surgery failed to restore or maintain the cervical lordosis
In May 2018, spinal surgeons operating in German and Egypt wrote in the medical journal Spine (10) about the problems of the second cervical neck surgery to fix the problems of cervical adjacent segment disease
Let’s focus on the fact pointed out by the researchers:
- “Anterior Cervical Discectomy and Fusion has provided a high rate of clinical success for the cervical degenerative disc disease; nevertheless, adjacent segment degeneration has been reported as a complication at the adjacent level secondary to the rigid fixation.”
We want to stress this point too: People benefit from this surgery, this article is for the people who don’t or maybe poor candidates for this type of surgery.
The learning point of this research is all about the curve of the neck
- 70 patients undergoing surgical treatment for adjacent segment disease after anterior cervical decompression and fusion.
- Surgery for adjacent segment disease was performed after an average period of 32 months from the primary Anterior Cervical Discectomy and Fusion.
- Adjacent segment disease occurred after single-level ACDF in 54% of cases, most commonly after C5/6 fusion (28%).
- Risk factors for adjacent segment disease were found to be preexisting radiological signs of degeneration at the primary surgery (74%) and bad sagittal profile (the curve was bad) after the primary anterior cervical decompression and fusion (90%).
CONCLUSION: Adjacent segment disease occurred predominantly in the middle cervical region (C4-6); especially in patients with preexisting evidence of radiological degeneration in the adjacent segment at the time of primary cervical fusion, notably when this surgery failed to restore or maintain the cervical lordosis.
The curve of the neck will be discussed further below
The surgery to fix the surgery. Revision and more fusion is no easy fix
The removal of implants secured through the endplates of adjacent vertebral bodies
Doctors at the Swedish Neuroscience Institute, Swedish Medical Center, in Seattle Washington led a study examining the failure patterns in standalone Anterior Cervical Discectomy and Fusion Implants. The study appeared in the September 2017 edition of the journal World Neurosurgery.(11)
Take home points:
- The goal of the study was to see how to help patients who suffered from Anterior cervical discectomy and fusion failure.
- Two-hundred eleven (211) patients were included in the study.
- There were 11 (5.2%) readmissions.
- There were 10 (4.74%) implant failures (five involving single-level surgery and five involving two-level surgery),
- There were seven cases of pseudoarthrosis (non-union fusion failure)
- Mechanisms of failure included:
- a C5 body fracture (the fusion cracked the vertebrae).
- Fusion in a kyphotic alignment following graft subsidence, (the bone/fusion collapsed causing a “hunchback,” curve in the patient).
- and acute spondylolisthesis, the condition of “slipped disc” or “slipped vertebra.
- Revision surgery following standalone anterior cervical implants can be complex.
- Surgery from behind Posterior (behind). Posterior cervical fusion remains a valuable approach to avoid possible vertebral body fracture and loss of fusion area associated with the removal of implants secured through the endplates of adjacent vertebral bodies.
Patients with cervical instability are getting surgeries that cause more instability and deformity
Doctors at South Korea’s Pusan National University published this research in the Journal of Korean Neurosurgical Society.(12)
What these researchers are warning is that the cervical spine and its attachment to the thoracic spine are more unstable than thought. This presents a paradox, patients with cervical instability are getting surgeries that cause more instability and deformity. Here is the result of this research:
The quick points:
- Thoracic spine involvement: Prior to Anterior cervical discectomy and fusion doctors should examine the T1 slope (for the correct or incorrect position) and C2-C7 sagittal vertical axis (this is a measure to determine if the spine is “plumb” in a straight line and correct balance).
- If these two factors are out of alignment there is a higher risk of kyphosis after laminoplasty (The bone/fusion collapsed causing a “hunchback,” curve in the patient), which is accompanied by posterior neck muscle damage.
- The researchers warn that these important preoperative parameters have been under-estimated in anterior cervical discectomy and fusion.
- Forty-one (41) patients who underwent ACDF with a stand-alone polyether-ether-ketone (PEEK) cage at one-year follow-up. Fifty-five segments (27 single-segment and 14 two-segment fusions) were included.
- The subsidence (collapse) and pseudarthrosis (non-union) rates based on the number of segments were:
- 36.4% collapse
- 29.1% non-union
- CONCLUSION: Surgeons should examine and be aware of the risk factors associated with T1 slope (for the correct or incorrect position).
Surgical correction of the cervical spine curve during fusion surgery. Does it help? Why doesn’t it help?
We would like to point out again that some people derive great benefit from the anterior cervical fusion surgery, again, these are the people we do not see. We see the people who had less than hoped for success.
In our non-surgical regenerative medicine injection techniques, we recognize that to help the patient who suffers from chronic neck pain, we must address and correct problems of the curvature of the cervical spine to achieve the best results. Surgeons also look at the curvature of the spine and its correction as a possible aid in helping their patients.
In December 2018 in the medical journal Therapeutics and Clinical Risk Management, (13) surgeons asked: “Is correction of segmental kyphosis necessary in single-level anterior cervical fusion surgery?” Here is how they answered that question:
- They examined 181 patients (99 males and 82 females) who underwent single-level ACDF surgery.
- There were 32 patients in the non-correction of curve group and 149 patients in the correction of the curve group.
- Surgical correction of segmental kyphosis in single-level cervical surgery contributed to balanced cervical alignment in comparison with those without satisfactory correction. However, the researchers could not demonstrate that the correction of segmental alignment is associated with better recovery in clinical outcomes.
What does this mean? It means that fusion is a complicated surgery and affects the natural movement of the neck, even when the natural curve of the spine is restored. Let’s go back to this study. The researchers focus on disc height at the fusion level.
- “On the basis of our general practice, we recommended that the restoration of disc height in the index level is essential to correct segmental angle. However, risk factors for progressive cage subsidence, such as endplate excessive resection and oversized cage insertion with excessive distraction, should also be avoided during surgery”
The benefits and risks in summary
As stated earlier in this article. There are patients who do very well with cervical fusion surgery. Some report 100% improvement some report close to 100% improvement. Others get some improvement and they are happy with that. As in any medical treatment, there has to be a realistic understanding of what the benefit may or may not be.
Here is an August 2020 paper published in the Journal of Orthopaedic Surgery and Research.(14) It gives a surgeon’s view of the realities of fusion surgery:
“For patients with two-level symptomatic adjacent segment disease, both anterior and posterior decompression and fusion were effective for improving the neurological function. For patients with radicular symptoms, Anterior Cervical Discectomy and Fusion surgery had less surgical trauma, better restoration of lordosis, and less postoperative neck pain, but higher chance of recurrent adjacent segment disease. Posterior decompression and fusion was an effective surgical option for older patients with myelopathy developing in adjacent segments.”
When you have fusion you can develop adjacent segment disease over the years and the challenges they bring are things to be considered when the first surgery is suggested.
The final outcome of a successful cervical fusion is that the vertebrae can no longer move.
The final outcome of a successful cervical fusion is that the vertebrae can no longer move. This will prevent the nerve from getting pinched, BUT, the neck still moves. The neck’s motion is now transferred to the vertebrae below the fusion and above the fusion. In essence, the problem the surgery sought to fix only transferred excessive pressures to the vertebrae below it and above it. This is why people with cervical fusions inevitably, a year to three years later get the symptoms back.
Now, by definition, that means if somebody is recommended a cervical fusion it means that the doctor is saying that it’s instability causing the problem. In my opinion, the best treatment for cervical instability is Prolotherapy of the neck, not cervical fusion. If it is the excessive movement of the vertebrae that is pinching on the nerves cause terrible pain, migraine headaches, vertigo, all types of symptoms, then Prolotherapy can strengthen the cervical ligament, address the symptoms and not rob the patients of their natural neck movements.
Bone spur development after cervical fusion
We are going to review a recent case:
- The patient is a woman in her late 60s.
- She came in with right-sided neck and shoulder pain and she had a lot of crepitus, a clicking sensation every time she would turn a certain way.
- She had stiffness, neck pain, and really muscle spasms or muscle tightness.
At 0:34 of the video, the patient’s digital motion x-ray shows problems surrounding her cervical fusion.
- We can see that the lower bones in her neck are not moving very well
- There’s also a very big reduction in space between these cervical bones so they’ve essentially fused together through the degenerative process
- She still has a lot of motion in her upper neck but there’s instability here between C2 and C3 and between c3 and C4 and that’s very common when you have a segment that is fused because your neck motion has to come from another part of the neck that typically becomes overworked and stressed.
Ross Hauser, MD at 1:05 talks about cervical fusion
- The problem with fusion is the unnatural distribution of force above and below the fusion. This unnatural force can lead to bone spurs and a “natural,” fusion of the segments above and below the cervical fusion. The bone spurs form to help stabilize the cervical neck instability caused in the adjacent segments of the cervical spine.
- Bone spurs form because of cervical ligament laxity. When the cervical ligaments are weak, stressed, and overused, they cannot hold the vertebrae in their natural position.
Bone spurs caused fusion in the adjacent segments can anything be done?
At 2:29 of video
- There are different levels of bone spur caused fusion. Sometimes a patients cervical vertebrae will have developed spurs and over growth so severe that we cannot move the spine to treat it. In other patients, with range of motion in the neck, we can realistically expect some change.
Summary and contact us. Can we help you? How do I know if I’m a good candidate?
We hope you found this article informative and it helped answer many of the questions you may have surrounding cervical adjacent segment disease. Just like you, we want to make sure you are a good fit for our clinic prior to accepting your case. While our mission is to help as many people with chronic pain as we can, sadly, we cannot accept all cases. We have a multi-step process so our team can really get to know you and your case to ensure that it sounds like you are a good fit for the unique testing and treatments that we offer here.
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