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Cervical Disc Replacement or Fusion? Surgery for arm and neck pain, numbness, tingling and weakness from neck arthritis, disc herniation (slipped disc) and radiculopathy
Last updated Thursday, December 31, 2009
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SummaryOverview Edited By: Michael J. Lee, M.D.
A commonly performed surgery for the treatment of a symptomatic herniated disc (“slipped disc”) is an anterior cervical discectomy and fusion (ACDF) (Figure 1). This operation involves removing part of the disc between the cervical vertebrae (neck bones), and fusing (surgically uniting) the adjacent vertebrae together. While this is effective in the treatment of symptoms of arm and neck pain, numbness, tingling and weakness, which often occur in patients with arthritis of the cervical spine (neck), there are some concerns about the possible longer-term effects of having the vertebrae (bones) of the neck fused together.
Imagine having a knee fusion. This operation, which is very occasionally done for treatment of severe infections that can’t be treated any other way, involves removing the joint at the knee and attaching the thigh bone (femur) to the shin bone (tibia), eliminating motion at the joint. At the end of the operation, the knee is locked in an extended (nearly) straight position. Though running difficulties not possible, walking usually is, but the absence of the joint increases the load seen by the other joints in the leg (including the hip and the ankle). Over time, those joints may become arthritic and Painful.
The same thing occurs in the spine. When two vertebrae of the neck are fused, the levels above and below see altered forces and motion, and this appears to give rise to degeneration (arthritis) at levels next to those fused. This is known as adjacent-segment degenerative disease.
Adjacent segment degeneration has been the driving force for the development of cervical total disc replacement (TDR). Total disc replacement in the neck is analogous in some ways to joint replacements elsewhere in the body, such as hip replacements or knee replacements, but there are some special issues unique to joint replacement in the neck, which this article will cover.
TDR is a new technology used to treat herniated discs (“slipped discs”) in the neck (Figures 2 & 3), which can arise. While both total disc replacement and the procedure described earlier (anterior cervical discectomy and fusion) remove the herniated disc, the fusion replaces the disc with bone, while TDR replaces it with a mobile implant (a joint replacement) designed to preserve motion. While in theory, this can prevent the occurrence of adjacent segment disease, long-term data is not yet available and this has not definitively been shown to be the case.
A herniated disc (“slipped disc”) or advanced osteoarthritis in the neck can narrow the space where the nerve root branches off of the spinal cord. This in turn creates pressure on the nerve roots. This pressure and accompanying inflammatory reaction causes pain, numbness, tingling, and weakness. There are other causes of this problem, but arthritis or a herniated disc are by far the most common.
When a nerve root or a branch off of the spinal cord is affected, the condition is termed radiculopathy. Radiculopathy can be treated with surgical and nonsurgical measures, including anterior cervical discectomy and fusion, or, in certain instances, total disc replacement
When the condition affects the spinal cord, it is termed myelopathy. In general, myelopathy in the cervical spine (neck) is a very serious condition, and frequently it is treated surgically; in very mild cases, myelopathy can be observed.
Both anterior cervical discectomy and fusion, as well as total disc replacement have been shown to be highly successful in relieving symptoms of radiculopathy.
Characteristics of cervical radiculopathy Radiculopathy commonly presents as arm pain, numbness and tingling down
the arm, occasional weakness in specific muscle groups (depending on
which nerve root is affected), and neck pain. Certain neck positions
can aggravate the patient’s symptoms. When radiculopathy occurs in the
leg, it is similar to what some patients call “sciatica.”
Myelopathy
can present as changes in walking patterns, clumsy hand coordination,
in severe cases, bowel and bladder changes. Reflexes can be exaggerated
with myelopathy.
Myelopathy and radiculopathy can occur at the same time and the patient can have a combination of these symptoms.
Types Vertebral discs are the doughnut-shaped, shock-absorbing structures
that sit between each vertebrae. An injury or trauma often herniates a
disc, causing part of it to push against a nerve root.
Radiculopathy
also can be a result of advanced arthritis in the neck or upper back.
Bone-spur formation can place pressure on the nerve roots. Similarly,
tumors can emerge around the spinal canal, putting pressure on the cord.
Congenitally,
cervical stenosis presents as a naturally more narrow spinal canal.
This condition can make a person more prone to experience
radiculopathy, especially if the narrowing progresses throughout life.Similar conditions The presence of certain neurological patterns and cervical stenosis
highly suggests that the patient’s symptoms are coming from the
cervical spine. However, other neurological conditions can mimic these
symptoms. For example, if a nerve is compressed in the arm, rather than
the neck, this can mimic symptoms of radiculopathy.
Occasionally,
an electromyography (EMG) test can help differentiate the source of
symptoms. In addition to other potential sites of nerve compression,
certain metabolic conditions like multiple sclerosis can mimic symptoms
of cervical stenosis.
Incidence and risk factors The main benefit of total disc replacement over fusion is the theory
that with preserved motion, there is less likelihood of adjacent
segment degeneration. The rate of adjacent segment degeneration with a
total disc replacement is unknown. The rate of adjacent segment
degeneration with a fusion is estimated to be 26.5% in a 10 year period
following the fusion. In an often quoted study, 26.5% of people
required an additional fusion at a level adjacent to a prior fusion.
However
it is important to note that many surgeons believe that adjacent
segment degeneration is a natural progression of arthritic changes in
the spine and not necessarily a result of the fusion.
Diagnosis Radiculopathy is diagnosed with physical exam. A variety of physical
exam tests examining muscle groups, the distribution of numbness and
tingling, and the quality of reflexes allows the physician to identify
which nerves are affected.
X-rays and MRI serve to confirm
diagnoses and provide more detailed information to help determine the
appropriate surgery. Occasionally, in a clinically challenging patient,
an electromyography (EMG) and nerve-conduction testing are done to
isolate the area of nerve injury.Medications Radiculopathy (nerve root compression) can be successfully treated with
anti-inflammatory medication (ibuprofen, Naproxen), which are sold over
the counter at drugstores and groceries. These medications decrease the
inflammation and can relieve the patient’s symptoms.
If these
medications fail, a steroid injection around the affected nerve can be
performed. The steroid injection delivers a higher concentration of
anti-inflammatory medication directly around the affected nerve.
It
is important that the patient be aware of the possible side effects of
these medications, including stomach irritation, kidney problems and
bleeding. If the patient has a history of difficulty with these
medications, other treatment options should be considered.
For each medication, patients should learn possible interactions with other drugs, the recommended dosage, and the cost.Exercises Therapy can provide some relief for radiculopathy. Traction exercises
can help relieve stenosis affecting nerve roots. These exercises can
provide enough relief until the radiculopathy has resolved.Possible benefits of cervical disc replacement vs. cervical fusion With both procedures, the radiculopathy symptoms of arm pain, numbness,
tingling or weakness are relieved with the removal of the disc
herniation or bone spurs pushing against the nerve. The surgeon removes
the offending disc(s) and/or vertebral bodies, and the spine and its
nerve roots are decompressed in the front. This part of the procedure
directly takes pressure off of the spinal cord and its nerve roots.
For
a fusion, a bone graft is placed to replace the removed tissue. This
bone graft fuses the cervical spine and stabilizes the neck. The bone
may be taken from the patient’s own pelvis (autograft) or from the
tissue bank (allograft –cadaver bone). Cadaver bone has been shown to
have excellent healing rates and avoids a second incision in the
patient at the hip.
In addition to the bone graft, a small
titanium plate is placed at the vertebral levels above and below the
affected vertebra to give additional stability to the fusion after
placement of the bone graft. (Figure 1)
For a total disc
replacement, instead of bone being placed where the disc was removed, a
mobile metal implant is placed. This implant engages the bony surface
above and the bony surface below for stability. There is motion within
the implant itself. This preservation of motion normalizes stresses at
adjacent levels and theoretically may decrease the likelihood of
further arthritic changes in the cervical spine. (Figures 2 & 3)Types of surgery recommended The cervical stenosis can be approached from the front (anterior) or
from the back (posterior) or the patient. The decision to approach the
spine from the front is dependent upon many factors, including:
• how many levels of discs and vertebrae are involved;
• the overall alignment of the cervical spine;
• the presence of radiculopathy, myelopathy, or both;
• the presence of neck pain;
• the extent of arthritis, and more.
The
surgeon weighs these factors and the results of a full diagnostic
workup, and recommends the surgical approach and procedure.
Who should consider cervical disc replacement vs. cervical fusion? Patients with radiculopathy can initially be treated nonsurgically.
Anti-inflammatory medication, therapy, and steroid injections can treat
radiculopathy. If these treatments fail and symptoms persist, surgical
intervention (fusion or disc replacement) is generally recommended.
Proper
patient selection for a total disc replacement is essential for a
successful outcome. Not all patients are candidates for TDR. A fusion
is still more commonly performed than TDR because of selection
criteria. A total disc replacement is FDA approved for a single level
use without prior fusion. In general, if there are extensive arthritic
changes in the cervical spine, a total disc replacement may not be the
ideal treatment choice as it only addresses arthritis in the front of
the spine. If there is extensive arthritis behind the spine, it will
not be affected by a TDR.
The use of TDR for myelopathy
(spinal cord compression) is under much discussion and has not been
well defined in the scientific literature.
What happens without surgery? Radiculopathy often can resolve with nonoperative treatment modalities,
and may not require surgery. Generally, surgery is required for those
who have significant neurological deficits like severe weakness, or for
those who have had extensive non-operative treatment with minimal
improvement.Surgical options Surgical options for cervical radiculopathy include
1) Disc removal and fusion
2) Total disc replacement
3)
Posterior Foraminotomy (an incision and decompression approached from
the back of the neck- not extensively discussed in this article).
Effectiveness In the hands of an experienced surgeon, both fusion and total disc
replacement are extremely effective in relieving symptoms of nerve root
compression. After the patient has healed from the fusion procedure,
the positive effects of surgery level can last decades. The benefit at
the treated level is long lasting, however there are concerns regarding
the adjacent levels. For disc replacement, we do not have extensive
long-term data on how well these implants perform, but the 2-5 year
data is very favorable.Urgency Both fusion and disc replacement for radiculopathy are not generally
emergent procedures. Many patients may not need surgery and may recover
with exercises, anti-inflammatory medication and steroid injections.
If
the patient has severe weakness, it may be more beneficial to the
patient to surgically decompress the nerve root earlier to maximize
recovery.
Risks Any surgical procedure carries a certain amount of risk. With these
surgeries, which approach the spine from an incision on the front of
the neck, these risks include, but are not limited to, infection,
bleeding, nerve injury, and swallowing difficulty. Swallowing
difficulty is fairly common early after surgery, but is expected to
resolve over the following weeks to months
For both ACDF and
TDR, there is a small risk that the implants may lose their fixation in
the bone and not function properly. If the metal implants have
migrated, a revision surgery may be required.
Managing risk In the rare event of a complication, measures can be taken to counter
them. If an infection emerges in the early postoperative period, a
surgical cleansing of the wound can be performed.
For disc
replacement, if the implants fail to achieve fixation in the vertebra
and if they migrate, revision surgery may be required. A failed disc
replacement may have to be converted to a fusion procedure.
For
fusion, if there is a nonunion, or if the bone graft does not fuse and
the patient has symptoms because of this nonunion, a fusion can be
performed posteriorly, or the fusion can be revised from the front.
Preparation Generally, blood transfusion is not necessary, so donation of blood
units is not needed, as is common in other surgical procedures.
Prior
to the surgery, the patient should have a thorough understanding of the
risks, benefits, and potential complications of surgical vs.
nonsurgical treatment. In addition, the patient should have an
excellent understanding of the goals of surgery. Depending on the
condition, the goals of surgery range from preventing further
neurological damage to relieving pain and symptoms.
Costs The surgeon's office should provide a reasonable estimate of:
• the surgeon's fee;
• the hospital fee;
• the degree to which these should be covered by the patient's insurance.
Surgical team A fellowship-trained spine surgeon should perform this procedure, as it
is technically demanding. It should be performed at a medical center
where these procedures are done routinely.Finding an experienced surgeon Because total disc replacement is a relatively new procedure, it is
unlikely that every community has an experienced spine surgeon who
performs many of these procedures. Surgeons specializing in spinal
procedures may be located through university schools of medicine,
county medical societies, or state orthopaedic societies.Facilities Surgery is usually performed in a major medical center that performs
these procedures on a regular basis. These centers have surgical teams
and facilities specially designed for this type of surgery. In
addition, neurological monitoring should be used, depending on the
patients’ condition and this should be avail. They also have nurses and
therapists who are accustomed to assisting patients in their recovery.Technical details Exposure
The exposure for total disc replacement and anterior cervical discectomy and fusion is the same.
After
the anesthesia is administered and the patient is given prophylactic
antibiotic, a horizontal incision (3 cm to 4 cm) is made on the front
of the neck. This incision is made in line with the way the skin runs,
so it can heal along skin lines with minimal scarring.
Dissection
through superficial muscle layers, around the midline esophagus and
airway structures, and onto the cervical spine is then performed.
Retractors are placed. An intra-operative X-ray is performed to confirm
the appropriate level of surgery.
The intervertebral disc is
then completely removed. Foraminotomies can also be performed. A
foraminotomy is the direct decompression of the space through which the
nerve root travels. Disc material or bone spurs can impinge in this
area, and place pressure on the nerve root. (Figure 5)
Total Disc replacement
After
removal of the disc, the disc replacement implant is inserted. X-rays
during the surgery are used to ensure the appropriate position of the
implant. (Figures 2 & 3)
Fusion
After adequate
decompression of the spinal cord and or nerve roots, a bone graft is
then impacted into place where the disc was removed, between the two
vertebrae.
A small titanium plate is then placed on top of the
bone graft and into the bone above and below Screws are placed into the
bone above and below to hold the plate in place. This plate gives
additional stability to the structure. (Figure 1)
Closure
The
surgical wound is then washed out, and the layers are closed with
suture. The skin is closed with an absorbable suture, and there is no
need for suture or staple removal. A drain is placed for 24 hours and
is removed the next day.
Anesthetic General anesthesia is necessary to perform this procedure. For spine
procedures, it is generally advisable to have the patient go to sleep
for their anesthesia than to be partially awake. With such meticulous
dissection around the spinal cord and nerve tissue, sudden inadvertent
patient motion may result in injury.Length of cervical disc replacement vs. cervical fusion In general, the procedure takes 45 to 90 minutes.Pain and pain management Shortly after the patient awakens from surgery, the patient is given a
PCA (patient-controlled analgesia) machine. This is a button that
allows the patient to self-administer pain medicine through the IV. The
pain medicine most commonly used is akin to morphine. This is usually
discontinued the next day, and the patient is given oral pain
medications.Use of medications Initially pain medication usually is administered intravenously or
intramuscularly. Sometimes patient controlled analgesia (PCA) is used
to allow the patient to administer the medication as needed.
Hydrocodone or Tylenol with codeine are taken by mouth. Intravenous
pain medications are usually needed only for the first day. Oral pain
medications are usually needed only for the first two weeks after the
procedure.Important side effects Pain medications can cause drowsiness, slowness of breathing,
difficulties in emptying the bladder and bowel, nausea, vomiting and
allergic reactions. Patients who have taken substantial narcotic
medications in the recent past may find that usual doses of pain
medication are less effective. For some patients, balancing the benefit
and the side effects of pain medication is challenging. Patients should
notify their surgeon if they have had previous difficulties with pain
medication or pain control.Hospital stay After surgery, the patient usually spends an hour or two in the
recovery room. The patient then goes to the hospital floor overnight.
The next day, the drain is removed and the patient is switched to oral
pain medication. Patients are commonly discharged the day after
surgery, but occasionally remain in the hospital for an additional day.Physical therapy The use of physical therapy is variable from patient to patient and can
be used for overall rehabilitation if the patient is deconditioned.
The
goal of physical therapy is long-term pain management and increased
function; it will not change the shape of the spinal canal.
Supervised cervical stenosis physical therapy may continue for weeks or months.
Rehabilitation options If prescribed, it is often most effective for the patient to carry out
exercises so that they are done frequently, effectively and
comfortably. Usually, a physical therapist instructs the patient in the
exercise program and advances it at a rate that is comfortable for the
patient.Can rehabilitation be done at home? Depending on the physical therapist’s prescribed program, some exercises likely can be performed independently at home.Long-term patient limitations After full recovery of the procedure, no long-term limitations on
activities exist. After a total disc replacement, it is advisable to
see your surgeon periodically (once a year) for x-rays to ensure
optimal function of the implant.Summary of cervical disc replacement vs. cervical fusion for cervical radiculopathy In the hands of an experienced surgeon, fusion and total disc
replacement are both very effective in relieving symptoms of
radiculopathy (nerve root symptoms form arthritis or slipped discs).
The
theoretical advantage of a TDR is that it may prevent further arthritic
deterioration in the cervical spine; however this has not yet been
definitively proven.
Not all patients are candidates for disc
replacement surgery. Depending on the extent of symptoms and arthritis,
some patients may be better treated with a fusion.
Surgery for Cervical Radiculopathy at the University of Washington, Department of Orthopaedics and Sports Medicine, Seattle, Washington If you are interested in making an appointment to discuss this procedure in Seattle, you can request an appointment using our online referrals website. To request a referral online, please click here. You can also call 206-598-4288 to make an appointment. Our clinical center is located in Seattle Washington, USA
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