Cervical adjacent segment disease: Risks and complications following cervical fusion

Ross A. Hauser, MD.

Article Outline

  • Understanding Anterior Cervical Discectomy and Fusion surgery, risks and complications following surgery.
  • Understanding the risk factors for cervical adjacent segment disease.
  • I am taking more painkillers now than I did before the ACDF surgery.
  • My sinus headaches and posture problems after fusion.
  • My ACDF was successful except for my new problems.
  • “Delayed and progressively worsening neurological problems following multi-segmental cervical spinal fusion.”
    • What is the evidence a patient has Atlantoaxial Instability? A past C2-C3 Fusion causing problems at C3-C7.
  • Researchers suggest that cervical fusion DOES NOT CAUSE adjacent segment disease.
  • Researchers suggest that cervical fusion DOES CAUSE adjacent segment disease.
    • The rapid formation of bone spurs, adjacent segment disease, neck pain, and cervical spine instability following surgery.
    • Maintaining the curve after fusion surgery can prevent adjacent segment disease.
    • After the surgery: Problems you may not have anticipated – For one: Your doctors don’t believe that there is anything wrong with you
    • Cervical fusion after a shoulder arthroscopic surgery – unforeseen problems.
    • The need for painkillers after surgery is a dangerous need.
    • Patients undergoing ACDF commonly receive high-dose opioid prescriptions after surgery.
    • Within 10 years, 1 in 4 patients can be at risk of clinical adjacent segment disease.
    • Anterior cervical spondylosis surgery: a retrospective study with long-term follow-up found that fusion significantly and negatively alters the curve in the neck.
    • The second cervical spine fusion makes the cervical lordosis even worse.
    • Surgery failed to restore or maintain the cervical lordosis.
    • The surgery to fix the surgery. Revision and more fusion are no easy fix.
    • 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.
  • Surgical correction of the cervical spine curve during fusion surgery. Does it help? Why doesn’t it help?
  • The final outcome of a successful cervical fusion is that the vertebrae can no longer move.
  • Bone spur development after cervical fusion.

What are we seeing in this image?

In this image, we see adjacent segment disease severely impacting the non-fused C6-C7 area. After two fusion surgeries, this 15-year-old patient’s only natural moving cervical segment is at C1-C2. This unfortunately is a classic case of fusion surgery causing more problems than it helped.

In this image we see adjacent segment disease severely impacting the non fused C6-C7 area. After two fusion surgeries, this 15 year old patient only natural moving cervical segment is at C1-C2. This unfortunately is a classic case of fusion surgery causing more problems than it helped. 

 

There are various surgical options to take out the bone, disc, and even ligaments to give the nerves more space. These include cervical fusion surgery, anterior cervical discectomy or corpectomy, posterior microdiscectomy, posterior cervical laminectomy, and of course, if the surgeon feels that so much tissue had to be taken out that the spine is now unstable, then a fusion also has to be performed. When compression of the spinal cord occurs because of severe cervical instability, anterior cervical decompression, and fusion are often the operation of choice, though artificial cervical disc replacements are gaining in popularity. The reasons for spinal arthrodesis or fusion of the cervical spine include:

  • to support the spine when its structural integrity has been severely compromised (to reestablish clinical stability),
  • to maintain correction following mechanical straightening of the spine in scoliosis or kyphosis following osteotomy/laminectomy of the spine,
  • to alleviate or eliminate pain by stiffening a region of the spine (i.e., diminishing movement between various segments of the spine), and,
  • to prevent the progression of deformity of the spine as in cervical scoliosis, cervical kyphosis, and spondylolisthesis.

The risks of spinal surgery include infection; excessive bleeding; adverse reaction to anesthesia; chronic neck or arm pain; inadequate symptom relief; damage to the nerves, nerve roots, or spinal cord; spinal instability; damage to the esophagus, trachea, or vocal cords; injury to the carotid or vertebral arteries; and subsequent stroke and non-healing of the fusion.

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 at our center 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. Some of these stories may sound like yours. In many cases, we can help people with post-surgical pain. cervical spondylosis

Understanding the risk factors for cervical adjacent segment disease

A July 2023 study in the Global Spine Journal (1) investigated the prevalence and risk factors for adjacent segment disease after anterior cervical discectomy and fusion. In this study, a total of 219 patients treated with anterior cervical discectomy and fusion were analyzed. The reported incidence of adjacent segment disease after fusion was 21%. The severity of osteoporosis, the impact of body mass index, and C2-C7 cervical sagittal vertical axis of cervical lordosis were significantly higher in the adjacent segment disease group than in the non-adjacent segment disease group.

An April 2023 paper in the North American Spine Society journal wrote (2) that patients with pseudarthrosis after anterior cervical discectomy and fusion (a symptom of failed fusion surgery – the slippage of the neck bones) may have concurrent adjacent segment disease. Although prior studies have shown posterior cervical decompression and fusion are effective in repairing pseudarthrosis, improvement in patient-reported outcomes has been marginal. (This is a situation where doctors believe the procedure should work better, and show better results than the patients themselves are reporting in follow-up).

“Improvements in patient-reported outcomes are marginal”

The researchers of this study sought to understand if revision surgery by posterior cervical decompression and fusion could achieve symptom relief in patients with pseudarthrosis after anterior cervical discectomy and fusion and whether results are impacted by the additional treatment of the patient’s adjacent segment disease.

  • Thirty-two patients with pseudarthrosis were compared with 31 patients with pseudarthrosis and concurrent adjacent segment disease after anterior cervical discectomy and fusion who underwent revision posterior cervical decompression and fusion with a minimum 1-year follow-up. It is noted that there was a significantly higher mean body mass index (BMI) in the group with concurrent adjacent segment disease.
  • Patients with concurrent adjacent segment disease had almost twice as many levels fused during posterior cervical decompression and fusion (3.7 vs. 1.9 average).

After evaluation of the patient group, the researchers concluded that “posterior cervical decompression and fusion is a standard procedure for the treatment of pseudarthrosis following anterior cervical discectomy and fusion, however improvements in patient-reported outcomes are marginal. Slightly greater improvements were seen in patients whose indication for surgery also included concurrent adjacent segment disease, rather than a diagnosis of pseudarthrosis alone.”

The risks of developing adjacent segment disease.

A January 2023 paper (3) led by doctors at Emory University, Keck School of Medicine, University of Southern California, Bergmannstrost Hospital in Germany, and The Johns Hopkins University School of Medicine examined the impact of these risk factors associated with the development of adjacent segment disease. Analyzing previously published studies and the patient data collected in these studies, the researchers found:

  • No significant differences for adjacent segment disease based on gender, BMI, smoking, alcohol consumption, diabetes, number of segments fused, and preoperative JOA score (assessment of motor and sensory function).
  • Significant risk factors were found for age, congenital/developmental stenosis, preoperative Neck Disability Index, preoperative VAS (neck pain scores), and preoperative VAS (arm pain or radiating pain scores).

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(4) “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. Below are some of the symptoms people revealed to us and the circumstances surrounding the development of these symptoms.

I am taking more painkillers now than I did before the surgery.

I recently had an Anterior Cervical Discectomy and Fusion. The fusion was only at two levels. The fusion did not help my arm pain or neck pain. It made these pains worse.  I now suffer from more problems including headaches and head pressure. I am taking more painkillers now than I did before the surgery. My doctors are not that concerned but I am. I was not told that these complications may be a risk for fusion surgery.

Again, let’s point out that many people have successful surgeries. A person like this would have to better understand their problems leading up to surgery and whether the surgery itself directly caused the headaches or whether the surgery fixed one area but left another area of the neck under more stress.

Patients undergoing ACDF commonly receive high-dose opioid prescriptions after surgery

In September 2019, researchers at Johns Hopkins University and the University of Virginia suggested in their research published in the Spine Journal (5) that “Patients undergoing ACDF commonly receive high-dose opioid prescriptions after surgery, and certain patient factors increase the risk for chronic opioid use following ACDF. Interventions focusing on patients with these factors are 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.

My sinus headaches and posture problems after fusion.

Listen to this person’s problem. How can we help with something like this?

I have had chronic facial pain and sinus headaches following a neck fusion a little over a year ago. It has limited my working out, I can no longer ride my bike because it hurts worse to lean forward. I feel constant pressure in my sinuses now and occasional pain between my shoulder blades. I do not have pain going down my arm or into my fingers. I have been through many spine surgeons and neurosurgeons. I do NOT want to have any more surgeries and fusion in my opinion is the worst operation ever on the neck.

In a person like this, once hardware failure or surgery-caused nerve damage is explored and excluded, we would focus on the adjacent neck segments to see if the fusion made a condition of worsening instability in the neck.

My Anterior Cervical Discectomy and Fusion surgery were successful except for my new problems.

Sometimes Anterior Cervical Discectomy and Fusion surgery are needed when there is a clear neurological impact impacting one’s ability to walk or have control of their bladder. Sometimes Anterior Cervical Discectomy and Fusion surgery can successfully correct these problems but leave behind others.

I had a successful Anterior Cervical Discectomy and Fusion surgery (ACDF) last year, I had balance and sense of space issues that caused me to stagger when I walked. The surgery restored strength and stability in my arms and legs. However I am experiencing worsening pain in my C1-C2 area, my fusion was C3-C7. I am now experiencing jaw pain and problems in my throat. I was told by my surgeon to have patience, my neck bones are fusing. I think the longer I wait to do something, the worse I will get. I get the feeling that my surgeon considers me successful and thinks that I do not need more help. 

Again, many people have had very successful surgeries. Stories like those above represent a small minority of cases post-surgery. However, people do have problems and sometimes we can help them with our various neck repair programs and injections.

“Delayed and progressively worsening neurological problems following multi-segmental cervical spinal fusion.”

Now let’s explore the research that stories like the ones above have a base in medical research. That they do happen.

First, we are going to explore a March 2020 paper presented in the Journal of Craniovertebral Junction and Spine (6) by a group of neurosurgeons from the Department of Neurosurgery, King Edward Medical Hospital, and Seth GS Medical College. 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 multi-segmental cervical spinal fusion.

The neurosurgeons described the cases of three male patients: a 34-year-old man, a 56-year-old man, and a 70-year-old man who all had C3-C6 fusion

In this paper, the neurosurgeons described the cases of three male patients. A 34-year-old man, a 56-year-old man, and a 70-year-old man, all had surgery for cervical spondylosis by multilevel C3-C6 cervical interbody fusion some six to eleven years earlier. After an initial improvement for a few years, the patients observed relatively rapid clinical deterioration. When admitted, all three patients were severely quadriparesis (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 directs 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:

The damage that instability is causing can be on the micro-level, invisible to MRI or other imaging devices.

  • 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 (7) 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 who had long-standing symptoms of progressive cervical myelopathy and where imaging showed the presence of C2-3 fusion, no cord compression related to the 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.)

Researchers suggest that cervical fusion DOES NOT CAUSE adjacent segment disease

A March 2022 study continues the controversial theme as to whether anterior cervical discectomy and fusion cause adjacent segment disease. Writing in the Journal of Biomechanics (8) doctors at the Department of Orthopaedic Surgery, University of Pittsburgh used a different set of diagnostic measurements to suggest that anterior cervical discectomy and fusion do not alter short-term adjacent segment kinematics in a way that would contribute to the development of adjacent segment disease. Here is what they wrote:

“The etiology of adjacent segment disease after anterior cervical discectomy and fusion (ACDF) remains controversial. Range of motion (ROM) is typically used to infer the effects of arthrodesis (fusion) on adjacent segment motion following ACDF, however, ROM only measures the total amount of motion. In contrast, the helical axis of motion (HAM) quantifies how the motion occurs and may provide additional insight into the etiology of adjacent segment pathology.” The helical axis of motion is another way of measuring rotation and movement in the joints.

Using this measurement the researchers reported:  “No differences in adjacent segment helical axis of motion (HAM) were found between patients with one- versus two-level arthrodesis. Neither symptomatic pathology nor arthrodesis appears to change the way motion occurs in the cervical spine during flexion/extension one year after one or two-level arthrodesis. These results suggest anterior cervical discectomy and fusion does not alter short-term adjacent segment kinematics in a way that would contribute to the development of adjacent segment disease.”

These findings were also suggested by a July 2022 paper (9) from the same University of Pittsburgh lead researchers which states: “This study provides in vivo evidence that contradicts long-held beliefs that adjacent segment end-range ROM increases appreciably after anterior cervical arthrodesis and that two-level arthrodesis exacerbates these effects.”

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, and physical therapy among other recommendations. Unfortunately, the patient did not respond to these treatments.

Surgery

  • 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. As demonstrated in the image below.

Maintaining the curve after fusion surgery can prevent adjacent segment disease.

In April 2022, researchers writing in the journal Quantitative Imaging in Medicine and Surgery (10) explored the effect of cervical alignment change after anterior cervical fusion. They noted “Adjacent segment pathology is one of the primary complications affecting the long-term efficacy of anterior cervical fusion. At present, the cause and mechanism of adjacent segmental lesions are still controversial.”

The purpose of this study was to explore these controversies and the research contradictions in reported successful cervical fusion outcomes. In this study, doctors looked at eighty-eight patients suffering from cervical spondylotic myelopathy who had been followed up for at least one year after anterior cervical fusion. The patients were divided into radiological adjacent segment pathology (RASP) and non-RASP groups according to the presence of postoperative radiological adjacent segment pathology. Note: Radiological adjacent segment pathology is the clear development of bone spurs and/or degenerative disc disease. and/or loss of the neck’s natural curve caused by the fusion. What the researchers found after examining the patients was that “Decreased cervical lordosis after ACF may be related to postoperative radiological adjacent segment pathology (RASP). Maintaining good cervical curvature after surgery may reduce the incidence of radiological adjacent segment pathology (RASP) after anterior cervical fusion.

This image shows digital motion x-ray of a bone spur at the adjacent level (C4-C5) that has formed since cervical fusion surgery. Cervical spine instability at C3-C4 is also shown in the offset above the fusion
This image shows a digital motion x-ray of a bone spur at the adjacent level (C4-C5) that has formed since cervical fusion surgery. Cervical spine instability at C3-C4 is also shown in the offset above the fusion.
  • 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, and 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:
  • 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 – For one: Your doctors don’t believe that there is anything wrong with you.

Above, research is cited to suggest that patient-reported outcomes should be better than patients are reporting.

A patient will tell us a story that goes something like this:

I have had neck pain for years. I have had many treatments and seen many doctors. I was told a long time ago to have a cervical fusion. I did not want the surgery so I tried chiropractic, physical therapy, various neck braces, collars, traction devices, acupuncture, yoga, supplements, and anything I could buy online that looked like it would help. Finally, my pain was getting worse and I was losing function. 

I had fusion for cervical stenosis. My surgeon told me the surgery was a success. My stenosis symptoms have vanished. But, since my surgery, I now have tinnitus, fullness in the ears, headaches, vision problems, balance issues, and nausea. I get hot and my skin gets blotchy red patches when I move my neck. I also have blood pressure swings. Then I developed an inability to keep my head up. The physical therapist called this dropped head syndrome.

My doctors do not think my fusion is causing these problems which I think are from upper neck instability. The answer is to send me back to physical therapy. Some of my doctors think this is a psychological problem. They have never heard of my symptoms occurring after fusion.

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.

A change in voice or voice damage

A February 2021 study in the International Journal of Spine Surgery (11) wrote that: “Injury to the recurrent laryngeal nerve has been implicated as a common complication following anterior cervical discectomy and fusion (ACDF) surgery.” The goal of this research was to assess the “true incidence of voice hoarseness and recurrent laryngeal nerve palsy following ACDF surgery, to determine the reliability of symptoms in the diagnosis of recurrent laryngeal nerve injury, and to evaluate factors related to the development of these symptoms.” Let’s explore what these researchers found.

  • In total, 108 patients were included in this study.
  • The average age was about 59 years old and the average patient was considered obese.
  • After surgery and excluding patients who were experiencing preoperative symptoms, 19 patients (20.4%) complained of dysphagia, 2 patients (1.9%) complained of aspiration symptoms, and 5 patients (4.6%) complained of voice hoarseness. There was no incidence of vocal cord palsy from postoperative laryngoscopy.

Conclusions: From the results of this study, the recurrent laryngeal nerve remained functional even a month after surgery despite several cases of postoperative dysphagia, aspiration, and voice changes.

Clinical relevance: “Voice hoarseness does not necessarily indicate recurrent laryngeal nerve injury after ACDF but may be caused by compressive forces on laryngeal tissue during retraction or intubation.”

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 therapy

  • 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

Cervical fusion after a shoulder arthroscopic surgery – unforeseen problems

Surgeons at Brown University wrote in the journal World Neurosurgery, (12) “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”

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 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 led to her initial fusion surgery. A lot of neck pain, muscle tightness from muscle spasms, and 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

The Horrific Progression of Neck Degeneration with Unresolved Cervical Instability

In February 2018, orthopedic surgeons wrote in the Journal of Orthopaedic Surgery and Research (13) 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 Germany and Egypt wrote in the medical journal Spine (14) 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 may be 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 are 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. (15)

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 the 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

In the image below we see the areas above and below a cervical fusion. The black arrow is pointing to a very large calcification. Areas below and above the spinal fusion are prone to become unstable. Over a period of time, the body will stabilize the areas via calcifications or bone spurs. Sometimes the bone spurs are so large that they cause problems with nerves and blood vessels by compressing them.

In the image below we see the areas above and below a cervical fusion. The black arrow is pointing to a very large calcification.
In the image above we see the areas above and below a cervical fusion. The black arrow is pointing to a very large calcification.

Doctors at South Korea’s Pusan National University published this research in the Journal of Korean Neurosurgical Society. (16)

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 underestimated in anterior cervical discectomy and fusion.

The findings:

  • Forty-one (41) patients 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 the 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 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, (17) 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 the 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. (18) 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 a 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 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 causes terrible pain, migraine headaches, vertigo, and all types of symptoms, then Prolotherapy can strengthen the cervical ligament, address the symptoms, and not rob the patients of their natural neck movements.

Ross Hauser, MD discusses a common condition that people reach out to us about-Adjacent Segment Disease. Some have been diagnosed with it, and others are concerned about getting it and want to avoid fusion surgery in the first place. In this video, Dr. Hauser discusses his experience with it and our approach to resolving instability without surgery by strengthening and tightening the ligaments that hold the vertebrae together with Prolotherapy.

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 by 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 by fusion. Sometimes a patient’s cervical vertebrae will have developed spurs and overgrowth so severe that we cannot move the spine to treat it. In other patients, with a good 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?

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References:

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This article was updated August 13, 2023

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