Cervical artificial disc replacement
Ross Hauser, MD. Caring Medical Regenerative Medicine Clinics, Fort Myers, Florida
David N. Woznica, MD. Caring Medical Regenerative Medicine Clinics, Oak Park, Illinois
Danielle R. Steilen-Matias, MMS, PA-C. Caring Medical Regenerative Medicine Clinics, Oak Park, Illinois
“Simply understanding ranges of motion (ROMs) does not capture the quality of normal cervical motion”
This introductory sentence to our article comes from surgical research. It represents the challenges some find with artificial cervical disc replacement. Also, let’s understand that there are many people who get great benefit from a cervical artificial disc replacement surgery. There are a lot of people who do well with the “hybrid” surgery of anterior cervical discectomy with fusion plus cervical artificial disc replacement surgery when multiple areas of the cervical spine are causing them pain. The people who have successful surgery are however, not typically the patients that we see in our office.
- We see the patient who were not considered a good surgical candidate
- We see that patient with new pain issues following the surgery that was suppose to resolve their old pain issues
- We see the patient who feels that their cervical spine could be stronger and more stable following the surgery
- We see the patient who does not want the surgery at all and are looking for realistic options for a surgical alternative.
Generally people who have had a successful Cervical artificial disc replacement surgery will report to us things like this:
- I feel great, the nerve pain is much less. I do have spasms in my neck and shoulders. I cannot resume my old activities yet and it is somewhat frustrating. I have been in Physical Therapy for 6 months. I may need more surgery because the other discs are now showing compression. I am looking for other options moving forward.
- I decided on the hybrid surgery. I had C6/C7 fused with anterior cervical discectomy with fusion (ACDF). My surgeon recommended to preserve range of motion I get the artificial discs at C4 and C5. The surgery went well, I take muscle relaxants mostly, painkillers sometimes. However, my neck does not feel strong and there is a concern that I may need more surgery.
The reason that these people come to our office is that they are exploring regenerative medicine treatments that may help them avoid surgery by strengthening their cervical spine by way of addressing cervical ligament damage and weakness. We will discuss this below. They may be in our office looking for ways to strengthen their cervical spine even after successful surgery. In some of these patients they recognize a weakness in their ability to “hold their head right.” There is a perceived instability.
What makes someone consider a cervical artificial disc replacement surgery?
For many people it is the new onset of a heightened and more constant pain. Pain may move into the upper back, the shoulders, down the arms. Even then these people may choose the route of physical therapy and other non-surgical measures until they are convinced these treatments will not help them. Eventually they may consent to surgery. In some cases three surgical options can be offered. A fusion surgery, a disc replacement surgery, or the hybrid fusion plus disc replacement.
Artificial Disc Replacement – Minimally Invasive Surgery – Who is it best for? Who is not a candidate?
In a cervical artificial disc replacement surgery, the herniated or damaged disc between the vertebrae is removed. As opposed to a fusion surgery where bone and graft are inserted into the void created by the disc removal and then the vertebrae of the cervical spine are held together with rods and screws, the artificial disc replacement surgery inserts a ball and socket joint apparatus. The idea is that this ball and joint can do the job of a natural disc by maintaining disc height and preventing the vertebrae from rubbing against each other, reduce compression on the nerves, and maintain mobility in the cervical spine and a proper range of motion.
As a minimally invasive procedure surgeons hope that they can complete the procedure within 2 hours, have the patient go home the next day, and have them return to a normal lifestyle within 2 months.
The benefits over spinal fusion in discussions between surgeons is
- Patients can move right away and do not need to wear a neck brace
- Faster recovery
- Better long-term relief than cervical spinal fusion
- Restored range-of-motion is very close to the range of motion of a healthy disc.
- Cervical disc replacement may not be the best option for people with significant spinal degeneration, multilevel herniation, loss of natural spinal curve, people with spinal cord compression. They, according to surgeon comparisons would benefit most from spinal fusion.
A comparison of surgical techniques
In new research, the discussion of how cervical surgery positively or perhaps negatively affects a patient is done via comparison of surgical techniques. This is demonstrated with a September 2019 study in the journal World neurosurgery (1). This research is lead by the Department of Neurosurgery, Seoul St. Mary’s Hospital, The Catholic University of Korea. Here the researchers “evaluated clinical and radiologic results as well as biomechanical changes after anterior cervical discectomy and fusion, cervical disc replacement, and posterior cervical foraminotomy . (a minimally invasive surgical procedure performed from the back) and/or discectomy in individuals with unilateral single-level cervical radiculopathy.
- A total of 97 patients received surgical treatment for unilateral intolerable radiculopathy.
- Clinical outcomes included pain scores for neck and arm pain, neck disability scores, and modified Odom’s criteria (A scoring system to assess the outcome of the cervical surgery.)
- Also measured was cervical spine range of motion for the whole cervical (C-ROM), operated segment (S-ROM), and upper and lower adjacent segment.
- A total of:
- 55 anterior cervical discectomy and fusion,
- 21 cervical disc replacements, and
- 21 posterior cervical foraminotomy were performed.
- Clinical improvement in neck disability and pain were significant after surgery; however, there was no statistical significance among groups.
- Satisfaction rate
- posterior cervical foraminotomy (76.2%)
- anterior cervical discectomy and fusion (90.9%) and
- cervical disc replacement (90.5%) without statistical difference.
- Range of motion was reported as only slightly better in the cervical disc replacements and posterior cervical foraminotomy groups, without statistical significance. Complete range of motion significantly increased in cervical disc replacement, slightly increased in posterior cervical foraminotomy group as compared to the results of the anterior cervical discectomy and fusion group, where cervical range of motion decreased.
- anterior cervical discectomy and fusion provides the lowest reoperation rate.
- Cervical disc replacement is effective in ameliorating cervical range of motions.
- posterior cervical foraminotomy has a greater probability of reoperation; however, range of motion after surgery is better than with anterior cervical discectomy.
Yet within the medical community is a debate between what is considered successful cervical artificial disc replacement, when cervical artificial disc replacement should be chosen over anterior cervical discectomy with fusion and when patients should reconsider the surgical recommendation.
If you can make the neck move more naturally, the better the chance treatment will have in achieving success.
Some of the controversial issues surrounding cervical neck surgery is the movement and range of motion, or lack thereof, of the cervical spine following neck surgery. Even in artificial disc surgery, there is a question as to how much, natural movement can be restored. In the above research and research below, a key benefit is the improved range of motion with the disc replacement.
“Simply understanding ranges of motion (ROMs) does not capture the quality of normal cervical motion”
In research from the Department of Orthopedic Surgery, Newton-Wellesley Hospital/Harvard Medical School, published in the Journal of orthopaedic translation, July 2019, (2) doctors wrote: “The subaxial cervical spine (C3, C4, C5, C6, C7) is the most mobile region of the cervical spine, allowing positioning of the head in a multitude of positions for various activities of daily living. As the discs degenerate, the relationship between alteration in kinematics (natural motion), resting alignment and symptom development is not clear.”
(Explanatory note: As cervical degenerative disease occurs, it is not clear what causes the development of the person’s pain challenges or what causes one person to have symptoms of cervical spine degenerative disease and why another person with similar degenerative disease will have no symptoms.)
- The research continues: “Surgical treatment of disc degeneration not responding to conservative measures with anterior cervical discectomy with fusion has been the gold standard although concern remains regarding development of adjacent segment disease. Although total disc replacement (TDR) and other motion-preserving technologies are becoming popular alternatives that are capable of restoring the cervical spine motion, recent follow-up studies indicated that symptomatic adjacent segment degeneration is not eliminated and reoperation rates of approximately 9% were reported at 24 months after surgery. The complications after total disc replacement surgery are thought to be caused by inadequate restoration of the in vivo (within) intervertebral kinematics of the affected segments. “(Note: How the c3-c7 segment moves after surgery).
Again, what the research suggests is that:
- For some patients symptomatic adjacent segment degeneration is not eliminated and reoperation rates of approximately 9% were reported at 24 months after surgery.
- The complications after total disc replacement surgery are thought to be caused by inadequate natural movement restoration
Returning to the research:
- “Simply understanding ranges of motion (ROMs) does not capture the quality of normal cervical motion, nor does it allow appreciation for the change in the quality of motion associated with disease development and restoration of quality motion through surgical treatment.”
The researchers of this study concluded that: “the subaxial cervical intervertebral center of rotation (the place where the vertebrae anchors itself to support rotation) and range of motions were segment level- and neck motion-dependent. (Each vertebrae had its own unique rotation and motions and fusing or replacing one or multiple segments will impact other non-surgical treated segments). This may help to improve the artificial disc design as well as surgical technique by which the neck functional motion is restored following the cervical arthroplasty.”
In other words, there is a concern that cervical spine disc replacement surgery does not restore the normal motion of the cervical spine in some patients and that this lack of normal motion can cause post-surgical complication and complaint. Doctors should look for ways to make the neck move more naturally. If they can, the better the chance the surgery, or any treatment will have in achieving better success.
Surgeons ask: “Are Controversial Issues in Cervical Total Disc Replacement Resolved or Unresolved?”
In the February issue of the Asian Spine Journal, (3) Neurologists in Korea published these findings in their paper: Are Controversial Issues in Cervical Total Disc Replacement Resolved or Unresolved?: A Review of Literature and Recent Updates.
Here are the summary findings and learning points:
- Since the launch of cervical total disc replacement in the early 2000s, many clinical studies have reported better outcomes of cervical total disc replacement compared to those of anterior cervical discectomy and fusion.
- However, cervical total disc replacement is still a new and innovative procedure with limited indications for clinical application in spinal surgery, particularly, for young patients presenting with soft disc herniation with radiculopathy and/or myelopathy.
- In addition, some controversial issues related to the assessment of clinical outcomes of cervical total disc replacement remain unresolved.
- These issues, including surgical outcomes, adjacent segment degeneration, heterotopic ossification, wear debris and tissue reaction, and multilevel total disc replacement and hybrid surgeries are a common concern of spine surgeons and need to be resolved. Among them, the effect of cervical total disc replacement on patient outcomes and adjacent segment disease is theoretically and clinically important; however, this issue remains disputable.
Heterotopic ossification- the growth of bone after cervical disc replacement
Heterotopic ossification is the unnatural formation of bone in the tendons, muscles, and other soft tissue. Speculation in the medical community that the acquired form of heterotopic ossification can occur when muscle is injured. Muscle is injured during surgery. Let’s look at the research:
Doctors at the Department of Orthopedics, The Third Hospital of Hebei Medical University in China wrote in the journal Medicine – (4)
- Occurrence of Heterotopic ossification is an inevitable postoperative complication after cervical artificial disc replacement and can decrease the range of motion at the segment where the disc was replaced. This they note is “contrary to the fundamental goal of artificial disc.”
- Previous studies reported various results on the occurrence of Heterotopic ossification.
- One study they cite reports 17.8% of Heterotopic ossification occurrence in studied patients at 12 months of follow-up
- Another cited study reported 78.6% patients exhibited Heterotopic ossification at an average follow-up period of 43.4 months.
- In this study, the results of Heterotopic ossification and severe Heterotopic ossification were grouped into different subgroups, and the pooled data showed that the prevalence of Heterotopic ossification after cervical artificial disc replacement was:
- within 1 to 2 years after surgery = 38% with a condition of severe Heterotopic ossification reported in 10.9%
- within 2 to 5 years after surgery, and = 52.6 with a condition of severe Heterotopic ossification reported in 22.2%
- within 5 to 10 years after surgery = 53.6% with a condition of severe Heterotopic ossification reported in 47.5%
What causes this?
Doctors at the Spine Institute of Louisiana wrote in a June 2018 study in the International journal of spine surgery (5) that it is difficult to understand why Heterotopic ossification happens.
- Heterotopic ossification is a known risk following cervical total disc replacement surgery, but the cause and effect of Heterotopic ossification are not well understood. Reported Heterotopic ossification rates vary, (as in the research documented above) and few studies are specifically designed to report Heterotopic ossification.
- The findings (of this study) are limited for clinical decision-making, because we cannot yet make causal inferences (a conclusion as to cause. The researchers concluded it happens, they are not sure why it happens. Other researchers have pointed out even if Heterotopic ossification occurs, many times it is asymptomatic and does not bother that patient at all.)
- The rates of Heterotopic ossification were shown to progress over time, warranting further research into the relationship of Heterotopic ossification and inflammatory response.
- There remains a paucity of literature analyzing potential surgical technique and implant-specific causes of Heterotopic ossification following cervical total disc replacement surgery. Further analysis needs to be conducted to understand the significance and relationship between each of these possible predictors, and other potential predictors, such as adjacent-level degeneration, sagittal alignment, and operative levels.
- Although spine surgeons have traditionally referred to Heterotopic ossification as clinically relevant (symptomatic) and nonrelevant (asymptomatic), this nomenclature (classification) appears to be founded on Range of Motion and not impact on clinical outcomes. Based on this analysis, the largest to date, it seems clear that Heterotopic ossification terminology should be more accurately defined as motion-restricting and non–motion-restricting.
We would like to point out that a possible causation is adjacent-level degeneration and possible problems with the cervical neck sagittal alignment. The cervical spine’s natural alignment or curve.
Cervical spinal alignment and curvature after disc replacement surgery
Let’s point out again that people have good success with cervical disc replacement. In some instances, documented in the studies we will cite below, the disc replacement helped restore, in part, the natural alignment of the neck. In others, the artificial disc caused an unnatural curve and alignment in the neck that caused complication.
In the European Spine Journal (6), medical university researchers in Italy researchers examined alignment at the cervical spine in patients following cervical disc replacement surgery.
Here is what they wrote:
“The alignment at the cervical spine has been considered a determinant of degeneration at the adjacent disc, but this issue in cervical disc replacement surgery is poorly explored and discussed in this patient population. The aim of this systematic review is to compare anterior cervical fusion and total disc replacement in terms of preservation of the overall cervical alignment and complications.”
“In most of the retrieved studies, a tendency towards a more postoperative kyphotic alignment in total disc replacement was reported. The reported mean (average) complication rate was of 12.5 % (0% in some research up to 66.2 % in other research). Complications associated with cervical prosthesis included heterotopic ossification, device migration, mechanical instability, failure, implant removal, reoperations and revision.
“Even though cervical disc arthroplasty (replacement) leads to similar outcomes compared to arthrodesis (fusion) in the middle term follow-up, no evidence of superiority of cervical total disc replacement is available up to date. We understand that the overall cervical alignment after total disc replacement tends towards the loss of lordosis, but only longer follow-up can determine its influence on the clinical results.”
Surgical treatments for Cervical Instability – the disc may not be the problem causing pain, loss of cervical curvature, and loss or range of motion
In our practice, we see many patients, not only with neck pain and radiating pain into the back, shoulders, arms and hands, but also with a myriad of symptoms related to cervical neck problems that doctors feel an artificial disc may help remedy, those related to degenerative cervical disc disease including problems of pinched nerves.
CREEP – cervical degenerative ligament disease – why neck surgery fails
Some of the most debilitating conditions attributed to problems in the neck are those due to cervical instability caused ligament laxity. What does this mean? It means that surgery may not address the problems you are experiencing in your neck.
When spinal ligaments are exposed to continued compression or stress, they “Creep.” Creep is a medical condition that results from the deformity or elongation of the ligaments that hold the cervical spinal vertebrae in place. This is cervical neck instability.
- The surgery that cuts away the cervical vertebrae bone that is pressing on the nerves – does not correct or prevent CREEP recurrence
- The surgery that will fuse the cervical vertebrae in place so the vertebrae do not shift out of place and press on the nerves again, MAY NOT be needed at all if CREEP can be repaired and prevented by the use of non-surgical regenerative medicine techniques.
- Regenerative medicine injection techniques such as H3 Prolotherapy explained below, work on the same understanding as fusion surgery, but with big differences.
- The regenerative injections repair the ligaments.
- The injections strengthen the ligaments’ ability to hold the vertebrae in its natural position. Which is what the fusion seeks to do.
- The big difference is that with fusion surgery you will lose a great amount of ability to turn your head from side to side and up and down. In Regenerative medicine injections the treatment repairs and allows for this natural movement of your head.
Range of motion issues are in the ligaments
A study came out of the University of Waterloo in Canada and was published in the November 2017 edition of the Spine Journal.(7) Briefly here was the problem and the goal of the study:
Loose ligaments are not normal
- Predicting physiological (normal) range of motion (ROM) using a finite element (FE) model (a numeric scoring system) of the upper cervical spine requires the incorporation of ligament laxity.
- COMMENT: The doctors understand that ligament laxity (CREEP) is a problem of stability and instability To come up with a scoring system to define the normal range of neck motion, you need to understand how loose ligaments are not normal.
Patients suffer from big problems caused by little damage to the ligaments
- The effect of ligament laxity can be observed only on a macro level of joint motion and is lost once ligaments have been dissected and preconditioned for experimental testing.
- COMMENT: It is hard on any level to accurately determine the amount of ligament damage to the amount of instability because even small injuries or damage, sometimes undetectable, cause big problems. This is what we call cervical ligament microinstability.
Patients suffer because Ligament laxity is a mystery
- As a result, although ligament laxity values are recognized to exist, specific values are not directly available in the literature for use in finite element models.
- COMMENT: Ligament laxity is a mystery, defining it within mathematical equations for the scoring system is difficult. This is why cervical neck pain patients have a difficult time finding the right medical care. Their conditions if based on degenerative ligament disease is a mystery.
Patients suffer because cervical ligament laxity is a mystery
Treating cervical ligaments – published research from Caring Medical
The capsular ligaments (the ligaments of the joint capsule) are the main stabilizing structures of the facet joints in the cervical spine and have been implicated as a major source of chronic neck pain. Such pain often reflects a state of instability in the cervical spine and is a symptom common to a number of conditions such as disc herniation, cervical spondylosis, whiplash injury, and whiplash-associated disorder, post-concussion syndrome, vertebrobasilar insufficiency, and Barré-Liéou syndrome.
When the capsular ligaments are injured, they become elongated and exhibit laxity, which causes excessive movement of the cervical vertebrae.
- In the upper cervical spine (C0-C2), this can cause symptoms such as nerve irritation and vertebrobasilar insufficiency with associated vertigo, tinnitus, dizziness, facial pain, arm pain, and migraine headaches.
- In the lower cervical spine (C3-C7), this can cause muscle spasms, crepitation, and/or paresthesia in addition to chronic neck pain.
- In either case, the presence of excessive motion between two adjacent cervical vertebrae and these associated symptoms is described as cervical instability.
Therefore, we propose that in many cases of chronic neck pain, the cause may be underlying joint instability due to capsular ligament laxity. Furthermore, we contend that the use of comprehensive Prolotherapy appears to be an effective treatment for chronic neck pain and cervical instability, especially when due to ligament laxity. The technique is safe and relatively non-invasive as well as efficacious in relieving chronic neck pain and its associated symptoms.
Stabilizing the unstable neck – the case for treating ligaments with Prolotherapy
Back to our 2014 research headed by Danielle R. Steilen-Matias, PA-C, published in The Open Orthopaedics Journal. Here we outline that the problems of the cervical neck are not always problems of degenerative disc disease but problems of degenerative ligament disease. This explains why traditional treatments focused on the discs will not be successful in the long-term.
The use of conventional modalities for chronic neck pain remains debatable, primarily because most treatments have had limited success. We conducted a review of the literature published up to December 2013 on the diagnostic and treatment modalities of disorders related to chronic neck pain and concluded that, despite providing temporary relief of symptoms, these treatments do not address the specific problems of healing and are not likely to offer long-term cures.
The objectives of this study are to provide an overview of chronic neck pain as it relates to cervical instability, to describe the anatomical features of the cervical spine and the impact of capsular ligament laxity, to discuss the disorders causing chronic neck pain and their current treatments, and lastly, to present Prolotherapy as a viable treatment option that heals injured ligaments, restores stability to the spine, and resolves chronic neck pain.
There are a number of treatment modalities for the management of chronic neck pain and cervical instability, including injection therapy, nerve blocks, mobilization, manipulation, alternative medicine, behavioral therapy, fusion, and pharmacologic agents such as NSAIDs and opiates. However, these treatments do not address stabilizing the cervical spine or healing ligament injuries, and thus, do not offer long-term curative options. In fact, cortisone injections are known to inhibit, rather than promote healing.
Research on 21 patients with cervical instability and chronic neck pain
In our research published in the European Journal of Preventive Medicine we presented the following findings:
- Ninety-five percent of patients reported that Prolotherapy met their expectations in regards to pain relief and functionality. Significant reductions in pain at rest, during normal activity, and during exercise were reported.
- Eighty-six percent of patients reported overall sustained improvement, while 33 percent reported complete functional recovery.
- Thirty-one percent of patients reported complete relief of all recorded symptoms. No adverse events were reported.
We concluded that statistically significant reductions in pain and functionality, indicating the safety and viability of Prolotherapy for cervical spine instability.(9)
In summary, disc replacement surgery can help a lot of people, however, cervical degenerative disease may also be a problem of the cervical ligaments. Addressing the problems of weakened and damaged ligaments may help in alleviating your problems of cervical degenerative disease.
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