Artificial Disk Replacement Surgery vs Spinal Fusion
Are you suffering from constant lower back pain? Is the pain making it difficult for you to carry out your everyday activities?
What is lower back pain?
The lower back is called the lumbar region. It is the area starting below the ribcage. Almost all of us experience lower back pain at some point during our lives. In fact, lower back pain has been reported as one of the top causes for missing work in the United States. It causes significant discomfort and pain to the sufferer and hampers with his/her everyday life. The pain ranges from a dull ache to a sharp shooting sensation. It makes it hard for you to sit or stand straight and move freely.
Causes of lower back pain
There are many possible causes of lower back pain. For instance, muscle strain is the most often reported cause. Your muscle is likely to strain due to heavy weightlifting and vigorous exercises. If your work or job includes pulling and lifting heavy objects, your spine might get twisted which can cause severe pain in your lower back.
Disk herniation is another cause of lower back pain. Your spinal cord is made up of a series of bones called vertebrae which are usually stacked upon each other and cushioned by jelly-like discs. These discs, covered within a tough rubbery case, work as a shock absorber to protect the spinal bones or vertebrae. If these discs slip or rupture anyway, their nucleus (jelly-like substance) pushes out of the annulus (outer cover) through a tear. This condition is called disk herniation and it causes severe pain in the back.
Besides muscle strain and herniated discs, sciatica can also cause significant back pain. When one of the discs bulges, it exerts pressure on the sciatic nerve which triggers pain running from the buttock and down to the legs. Other little unknown causes of lower back pain include carrying a heavy purse, briefcase, or backpack, overdoing it at the gym, or being overweight and sedentary. Your lower back supports your upper body and the weight you carry. Thus, heavy weights put greater stress on your lower back, especially when you carry it every day. Moreover, excessive exercising causes overextension of your muscles, causing pain.
Last but not the least, there are many chronic conditions causing lower back pain like:
- Spinal stenosis
- Ankylosing spondylitis
The first condition, spinal stenosis, is characterized by the narrowing of space around the spinal cord. It exerts pressure on the spinal nerves resulting in pain and discomfort. The second condition, ankylosing spondylitis, is the inflammation of the spinal joints causing stiffness and chronic pain in the back. Sometimes it also occurs due to inflammation of joints in the shoulders, ribs, and hips. In extreme cases, spinal vertebrae start fusing or growing together. Lastly, fibromyalgia is a disorder causing musculoskeletal pain along with extreme fatigue, sleep, memory, and mood issues. The condition augments painful sensations by hampering signal processing through the brain and spinal cord. It potentially causes prevalent muscle aches, including back pain.
Non-surgical treatment for lower back pain
Often, lower back pain gets better on its own, sometimes within 72 hours. However, if it doesn't, you should see your doctor before it becomes a more serious issue. Lower back pain is considered chronic if it lasts for more than 3 months. Your doctor may prescribe some effective treatments and give you suggestions to improve your situation. However, the treatment procedures usually vary with the cause of the condition. To be accurately diagnosed, it is important to be very specific in describing the type of pain you feel, its symptoms, location, and any medical history of chronic conditions.
In the initial stages, back pain is treated with non-surgical procedures. In case of slight pain, a little exercise, or a healthy workout, heating pads, and warm baths work great. The first few medical approaches for dealing with lower back pain include:
- Massage therapy
- Spinal manipulation
In these cases, your doctor or therapist uses physical exercise and hand massages to cater to the situation. However, in severe cases, acupuncture and medicine may also be recommended. And when all the non-surgical procedures fail to relieve your pain, surgical options may be suggested.
Surgical treatment for lower back pain
As a patient of constant lower back pain, especially when it is making your everyday life difficult, you should consider reliable surgical treatments to restore your ability to function properly. Experts recommend surgery if at least six months of aggressive nonsurgical treatment has failed to help you.
The two most common surgical treatments for addressing lower back pain are:
- Lumbar spinal fusion
- Artificial disc replacement (ADR)
Lumbar spinal fusion refers to the traditional approach of treating pain and disability from the lumbar degenerative disc. It involves forming a direct bony connection between the painful discs and vertebrae to stop the motion of the discs that are causing pain. The other treatment approach called lumbar disc replacement is a type of spine surgery that involves replacing degenerated or worn-out disc in the lower spine with an artificial one. The artificial disc is usually made of metal or a combination of metal and plastic. Where spinal fusion aims at joining the vertebrae together, lumbar ADR works by replacing it.
These two treatment approaches are often looked upon as the two most promising surgical procedures for lower back pain due to disc herniation. People often get confused about which one is right for them. Thus, Sierra Neuroscience Institute brings you a detailed comparison of the two approaches so that you, along with your doctor, can decide which one is better for you.
Lumbar spinal fusion
Lumbar spinal fusion, as mentioned above, is a permanent surgical approach to connect two or more vertebrae in your spine. It aims at eliminating the motion between them. Spinal fusion includes techniques that are exclusively designed to simulate the natural process of healing in broken bones. During the process, the doctor or the surgeon works to place bones or bones-like material within the space between the two affected spinal vertebrae. The practitioner may use screws and rods to hold the vertebrae together so that they heal into a solid entity. This surgical procedure is likely to connect your vertebrae in your spine permanently and promises improved stability and corrects any deformities, reducing the pain due to vertebrae dysfunction.
Most of the doctors recommend spinal fusion surgery for treating:
- Deformities in the spine
- Weakness and instability of the spine
- Disc herniation
- Lumbar degenerative disc disease
- Lumbar Spondylolisthesis (isthmic, degenerative, or post-laminectomy spondylolisthesis)
In case of spinal deformities, spinal fusion works well for scoliosis, or the sideways curvature of the spine. Also, your spine can lose its stability due to abnormal or excessive vertebral motion. This might also occur due to severe arthritis in the spine. In such a case, spinal fusion is carried out to restore spinal stability. Lastly, this procedure is utilized for spinal stabilization when your damaged or herniated disk is removed.
There are a wide variety of spinal fusion procedures available. Each one of them has its pros and cons. These techniques can be carried out either from the front, back, or both. The internal structural support during bone fusion is provided by spinal instrumentation as implants or pedicle screws while the bone graft is either harvested from the patient, synthetic bone graft substitutes, or extenders. All this is done to stop the motion of the vertebral segment causing you pain. Almost all the approaches for lumbar spinal fusion follow the process mentioned below:
- Addition of a bone graft to a spinal segment.
- Setting up a biological response causing the growth of the added bone graft between the vertebrae. This is intended to create a bone fusion.
- Formation of the bony fusion resulting in a fixed bone as a replacement for a mobile joint. This is where the motion at the joint segment stops.
Types of spinal fusion
As mentioned, there are several technical options available for spinal fusion surgery. Based on these options, the types of spinal fusion surgeries are:
- Posterolateral gutter fusion (PGF): this is the type of spinal fusion involving bone grafting in the posterolateral portion of the spine. This is the region right outside the spine. This procedure has a long history and is the "tried and true" method of fusion by the majority of surgeons.
- Posterior lumbar interbody fusion (PLIF): This type of spinal fusion is also done from the back and involves removal of the disc between the two vertebrae and inserting the space between the consequent spaces. The only difference between the two is that unlike PGF, the PLIF works by inserting a cage of allograft bone or synthetic material. In addition, PLIF is usually supplemented by a simultaneous posterolateral spine fusion.
- Anterior lumbar interbody fusion (ALIF): This fusion procedure was first performed by Dr. Cloward in the 1950s. This procedure is much similar to PLIF but is done from the front.
- Anterior/posterior spinal fusion: This surgical procedure is done from both the front and back.
- Transforaminal lumbar interbody fusion (TLIF): Although this procedure is carried out from the back, it works to fuse the anterior and posterior spinal columns. The anterior portion of the spine is stabilized by an interbody spacer and bone graft. The posterior column is locked in place using a bone graft, rods, and pedicle screws.
- Extreme lateral interbody fusion (XLIF): In this fusion type, the surgeon fuses the lumbar spine from the lateral side of the spine rather than from the front and back. This type of surgery cannot be used for all types of lumbar conditions like the lowest level of the spine.
What can you expect during a fusion surgery?
During the cervical fusion surgery, the patient is given general anesthesia. The technique and type of fusion that is carried out depends on the location of the vertebrae which is to be fused, your body shape, and general health.
The general surgical procedure is carried out as follows:
- Incision: For accessing the vertebrae to be fused, the surgeon makes an incision in one of three locations including your neck or spine back, your throat or abdomen, or on either side of the spine. In the case of the throat and abdomen, your surgeon accesses the spine from the front.
- Preparation of bone graft: Bone grafts are the basic tools for fusing the vertebrae. They may come from your own body (from the pelvis region) or a bone bank. If your bone is used, you're likely to get an incision over your pelvic bone. The surgeon removes a small portion and then closes the incision. In some cases, doctors use a synthetic substance in place of bone grafts which helps to promote the growth of the bone, speeding up the process of vertebral fusion.
- Fusion: The final step is the vertebrae fusion where the surgeon places the bone graft material between the vertebral spaces. Screws, rods, and metal plates are used to hold the vertebrae together while the bone graft heals.
After spinal fusion
You are likely to stay at the hospital for two or three days after the surgery. The length of your hospital stay can be extended or reduced, depending on the location and extent of the surgery. A little pain and discomfort can also be expected for which pain-relievers and other medicines can be given. After you are discharged, stay in touch with your doctor and immediately inform him/her if you experience shaking, chills, high fever, wound drainage, redness, swelling, or tenderness. It might take months for the bones to heal and fuse completely. During that time, you need to keep your spine aligned properly. Physical therapy is recommended to maintain proper spine alignment.
Are there any risks associated?
Lumbar spinal fusion is generally a safe process but it carries some risk of complications. Some of the potential risks associated with the surgery are:
- Blood clots
- Poor wound healing
- Injured blood vessels and nerves around the spine
- Pain at the site of incision site
Keep in mind that despite executing a successful fusion, there is a chance that your pain may not go away. However, in most of the cases, lumbar spinal fusion surgery is very effective, especially for the conditions involving one vertebral section only. There are many factors that contribute to the success of spine fusion surgery like:
- Accurate diagnosis prior to the operation/surgery
- An adept surgeon
- A patient with a healthy lifestyle
- Patient motivation to pursue rehab and restoration
Most patients notice limited motion even after level one spine fusion. If necessary, level two fusion is also carried out. More than 2 levels are not usually recommended because it stresses the remaining joints and restricts much of the normal motion. But in case of scoliosis and deformities, level three or more fusion levels may be carried out.
Lumbar Artificial Disc Replacement
Another popular surgical option for treating damaged lumbar discs is artificial disc replacement. This procedure is designed to alleviate the lower back pain caused by disc herniation. It works by replacing the painful discs with artificial ones and locking the free motion at the particular spinal segment.
This prosthetic implantation is similar to artificial knee joint and hip surgeries used by orthopedic surgeons. These surgeries not only relieve the pain but also maintain motion disturbed by arthritic joints. The only difference between the two is that in the case of hip and knee joint surgeries, the total joint is replaced while in the case of lumbar discs, only one of the three joints at the vertebral level is replaced.
Everyone with lower back pain isn't a good candidate for acquiring disk replacement. Therefore, proper medical diagnosis and tests are necessary to determine if the procedure is right for you. Following are some of the situations where artificial disc replacement is recommended:
- Lower back pain coming from 1 or 2 lower spine discs
- No significant joint disease or compressed spinal nerve
- Normal weight and BMI
- No previous history of spinal surgery
- No spinal deformities or scoliosis
Once you've gone through the medical history and physical tests, your doctor will suggest blood tests, CT scans, MRI, and X-rays. This is crucial in identifying the nature and extent of your back and spinal damage, which is essential for deciding if the procedure is right for you.
Getting ready for the disc replacement surgery
Once you have been prescribed artificial disc replacement surgery, there is a whole process for getting yourself prepared for it. For instance, you may be asked to stop smoking as a part of getting ready for the surgery. You may be told not to eat and drink anything several hours before the surgery. You may not be allowed to drive and carry out your everyday activities. Most importantly, you need to tell your doctor about all the prescriptions and medications you're taking.
What happens during the surgery?
First of all, you'll be given an anesthetic through a vein, with an IV line put into it, in your hand or arm. For the surgery, you'll be lying on your back. The procedure is usually carried out by a team of surgeons including an orthopedic, neurosurgeon, and vascular surgeon. They will make an incision in your abdomen to access your spine. The damaged disc shall be removed and a new artificial or prosthetic disc is placed or implanted. The incision is now closed. Next, you'll be taken to a recovery area where you'll be closely monitored.
You'll be required to stay in the hospital for a few days after the surgery. Since the post-surgery procedure doesn't involve bone healing, the recovery period may be much faster. Pain relievers are always recommended on-demand. The patient is encouraged to stand and walk after one or two days. The doctor may recommend some exercises to train your spine safely. It is necessary for a speedy recovery.
Are there any risks associated with ADR?
Like all surgeries, lumbar ADR also pose some risks. First of all, artificial disc replacement demands greater spinal access than cervical fusion surgery. Other associated risks are:
- Infection in or around the area of the artificial disk
- Displacement or dislocation of the artificial disk
- Implant failure
- Fracture or breaking of the artificial disc
- The implant might wear and tear
- Breaking down of the spinal bones causing stenosis (i.e. narrowing of the spine)
- Problems due to a poorly positioned implant
- Stiffness or rigidity of the spine
- Blood clots in legs due to decreased activity
Depending upon your specific condition, other risk factors can also be anticipated. Be sure to discuss all these concerns with your doctor and consult him/her more.
Spinal fusion or disc replacement: which is better?
Since artificial disc replacement can treat only limited types of disc pathology, fusion surgery remains much prevalent due to its wide condition-coverage. Some of the considerations for both the procedures are the same. For example, the anterior lumbar interbody fusion and artificial disc replacement use an anterior approach which is likely to present similar risks and complications. However, most of the considerations are unique for each type, which will need to be discussed with your doctor.
Before choosing any one type of surgery, it is essential for the patients to know that not all types of lower back pain are treatable. Clinical failure can be expected in both types. Now, let's begin with a critical evaluation of each type for making a choice between the two.
Evaluating the disease condition
Considering lumbar spinal fusion first, it works best for disc-related back pain, degenerative disc disease, arthritis of the facet joints, spinal instability-associated pain, and progressive spinal deformity. However, lumbar artificial disc replacement, or total disc replacement, works exclusively for painful lumbar discs. The treatment demands certain health restrictions like little or no arthritic changes for the facet joints. Moreover, the patient must have no medical history of spinal injury or surgery before, no previous osteoporosis, no pre-existing instability of the spine, or abnormal curvature. Also, the patient must be healthy enough to withstand postoperative pain and complications.
Evaluating the procedure
Varying with the type of spinal fusion (anterior, posterior, lateral, etc.), the location of the surgery might vary but the general procedure remains the same which is an incision, bone grafting, and fusion. An incision is made on the desired location to access the spine, a bone graft is added, a metal rod or a supporter is inserted to hold the two together, the incision is closed, and the bone is allowed to heal. If you don't want to use synthetic bone grafts and metal rods, auto-grafting and bone morphogenetic proteins or BMPs are also available. In auto-grafting, the doctor uses your own body bone or tissue and transfers it from one spot to the surgical one as a bone graft. Secondly, bone morphogenetic proteins (BMPs) are a group of growth factors called cytokines and metabologens which play a crucial role in the morphogenesis of the bone. They are likely to omit the use of metal rods and screws for internal fixation. Using these natural options, you can expect minimum risks and complications from spinal fusion and can opt for it as a safe surgical option for fixing your bones and discs.
For artificial disc replacement, there are no natural alternatives as present in a cervical fusion. You have to get prepared an artificial disc for replacing the damaged, herniated, or painful discs in your vertebrae. The surgical approach for ADR is a bit risky because it involves abdominal incision followed by organ movement for accessing the spine whereby the artificial disc is inserted. The procedure requires great care because some of the vessels are present directly on the front surface of the spine and they must be moved carefully and protectively for avoiding any vascular damage. This is why ADR surgery is carried out by a triad of surgeons to avoid any complications.
Evaluating the results of the procedures
The first and the foremost thing to be considered regarding both the procedure is their effect on disc mobility. Whether or not the procedure was successful enough to stop the painful motion of the herniated discs and facet joints. If the patient has severely limited motion due to pain, the success of the procedure will be measured by the extent to which it relieved the pain and restored normal motion.
Spinal or cervical fusion is needed for long-term relief from the pain. However, the procedure doesn't guarantee 100% pain relief. The clinical success and satisfactory improvement of the pain is reported among 50-80% of the patients only. Therefore, you can never say that successful fusion guarantees pain relief. The reason behind it may be the diagnostic challenges and such a condition is called failed back surgery syndrome when the patient continues to have pain even after successful fusion. ADR, it also cannot guarantee 100% pain relief and replicate normal spinal motion. Each implant design gives rise to different motion patterns. Some cases also report that patients who've undergone artificial disc replacement surgery experience high posterior facet joint degeneration caused by abnormal motion of the artificial disc.
Evaluating the risks and complications
The potential risks and complications associated with lumbar spinal fusion depend on the type of surgical technique used. For instance, some of the potential complications are as follow:
- Almost 1-5% of the cervical fusion cases report postoperative wound infection. It is much higher during metallic fixation. Most of the patients reporting the infection are either overweight or diabetic.
- In the first 6 to 8 weeks following the surgery, patients might experience pain from the bone graft site in the pelvis. In 15-30% of cases, this pain persists and becomes chronic.
- Pseudo-arthrosis is reported among 5-40% of the cases. It is basically the failure of bone healing and its likelihood depends on the specific surgical technique used and the individual risk factors of the patients. For example, using metallic implants, the fusion may not heal which will eventually result in breakage or loosening of screws and rods inside. People who smoke have a lower chance of successful fusion.
- Persistent pain due to pseudo-arthrosis. It might necessitate additional surgery to get the fusion healed. A revised surgery is more complicated than the first procedure and may offer more risks.
- The operative spinal segments are usually stiffened with spinal fusion which exerts an added stress with spine motion on the remaining mobile discs. It might initiate the process of disc degeneration of adjacent discs which may trigger the need for additional surgery to address degeneration and its consequent instability and nerve compression.
Considering ADR, the major complication associated with the procedure includes injury to the blood vessels and organs in the abdominal regions. It includes vessels bringing blood from and to the legs. Furthermore, any mishandling may also damage the ureters, i.e. tubes carrying urine from the kidneys to the bladder and small or large intestines. Among the male patients of ADR, there is an additional complication called retrograde ejaculation reported among 2-5% of the males. In this case, the males have normal orgasms, erections, and penile sensations but they cannot ejaculate. The semen moves into the bladder and is released through urine. Many healthcare experts suggest that males who are about to acquire ADR should bank their sperm if they intend to start a family after the surgery.
In the case of early implants, complications may include migration of the endplates to the central core of the implanted artificial disc. This is unlikely to occur but is one of the anticipated risks of the surgery. These problems may arise due to problems in the initial implant positioning or unrecognized instability of the spine. Such a condition, if it occurs, demands urgent revision with replacements and might convert the approach to cervical fusion.
There are rare chances that the implant may fracture after the surgery or it may cause the vertebrae to fracture. If this occurs, the patient may be placed in a brace and a revision surgery could be expected. Other late complications may include subsidence or collapse of the implant causing limiting implant movement. With time, the implant may wear out and need to be inserted once again. However, many European studies indicate that wearing out of the implant is much less likely to occur even after 10-20 years after the surgery. 2-3% of the ADR patients also reported late infections which could possibly be treated with antibiotics. If the complications keep on increasing, the procedure may be shifted to fusion.
The best option?
Nothing will replace a full and frank discussion of all the surgical and non-operative choices together with your operating surgeon, or multiple surgeons.
Additionally, consider a reliable surgeon with expertise in both artificial disc replacement and anterior spinal surgery. They can let you know which procedure might work well for you.