What is ADR surgery?
In cases of disc degeneration in which either cervical or lumbar conditions cause radicular pain (nerve) surgery is necessary if conservative medical treatment has not been effective.
In these cases, the most commonly performed procedure is lumbar or cervical fusion or fixation.
We believe that ADR (Artificial Disc Replacement) surgery is a better alternative to fusion surgery and much less invasive. It consists in the replacement of degenerated lumbar or cervical discs with an artificial implant designed to mimic the healthy natural disc.
Minimally-invasive lumbar spinal surgery
The most common spinal conditions which we deal with at Barcelona Spine Center are lumbar disc herniation, lumbar canal stenosis and other conditions that can be treated with lumbar instrumented arthrodesis. Amongst the latter are: lumbar spondylolisthesis, lumbar canal stenosis associated with spondylolisthesis, adult scoliosis, hernia recurrence and low back pain due to lumbar degenerative disc disease.
At Barcelona Spine Center the non-invasive approaches that we use in these cases are based on tubular progressive expansion systems. This procedure achieves, by means of small incisions, the same results as open surgery.
In surgeries where accurate placement of instrumentation is necessary, we use a GPS to determine the exact location within the spine. This significantly decreases mal-positioning that can injure nerve structures. This GPS navigation system is known as O-arm. Barcelona Spine Center has installed the first system used in Spain.
Intraoperative neurophysiological monitoring is also very helpful, especially in complex adult scoliosis surgery or reoperations.
Neurophysiological recording is another extra safety measure. A Neurophysiologist constantly monitors nerve conduction during surgery. Any alteration in nerve conduction caused by minimal misplacement of an instrument is detected by our intraoperative registration systems and allows intraoperative correction of instrumentation placements.
Finally, we must say that total disc replacement using ADR is a less invasive technique because all the back muscles are preserved, no vertebral osteotomies are performed and better exposure is achieved to perform lumbar disc removal. It is also the non-invasive technique with the fastest recovery.
Minimally-invasive cervical spinal surgery
Cervical disc hernias can be treated by a non-invasive posterior approach, making a small incision and using tubular retractors to dilate the muscles.
Disc hernias are usually treated using an anterior approach, with almost total discectomy and herniated disk replacement by a new artificial disc. The advantage of the above approach is that no vertebrae bone excision or dissections of the posterior muscles are necessary. Moreover, hernias are always anterior to nerves, thus there is less need for manipulation with an anterior approach.
Said anterior approach, followed by discectomy and replacement with an artificial disc, is also used in cases of cervical degenerative disc disease that cause cervical pain.
In cases of advanced cervical osteoarthritis in patients of more than 70 years of age with significant spinal cord compression we do not use the ADR technique here at Barcelona Spine Center because it is not indicated. In such cases, the technique used is cervical arthrodesis with an intersomatic cervical cage involving one or more levels, followed by placement of a cervical plate.
As in lumbar surgery, during cervical surgery navigation and intraoperative monitoring during placement of posterior instrumentation are extremely useful.
Intraoperative neurophysiological monitoring (IONM) is frequently used to protect nerve structures during surgery. Continuous recording of nerve conduction makes it possible for a neurophysiologist to let us know if a maneuver or malposition of instrumentation can lead to injury. It is especially useful in patients with spinal cord injury prior to surgery or placement of posterior instrumentation.
Types of ADR
The first lumbar disc replacement surgeries were performed in the 80s In the 90s this operation became popular with improved designs and materials and we began to carry out our first procedures in 2000.
Over time, materials, and especially designs, have improved substantially, and now the prostheses implanted are known as “third generation” with good resistance to wear and biomechanical behavior very similar to the natural disc. This makes it possible to perform surgeries with greater safety and improved clinical outcomes. Therefore, in the past eight years ADR surgery has become the best option in cases of lumbar and cervical degenerative disc disease.
DISC NUCLEUS REPLACEMENT
Disc nucleus replacement (core prosthesis) is not possible in the case of cervical discs due to their size, there are complications and poor clinical results have been obtained in different pilot studies over the years.
In the late 90s and up to 2010, different core prosthesis were marketed based on different designs and different artificial substitutes for lumbar disc nuclei.
In 2007 physicians at Barcelona Spine Center participated in a multicenter study of Custom Implantable Medical Devices together with several other European centers.
We thought that if it were possible to design a made to measure prosthetic nucleus this would reduce the incidence of subsidence and extrusion. In addition we looked for the best possible material: polyurethane with very similar characteristics to a lumbar disc. However, significant difficulties in implementation arose and clinical outcomes were of limited success since the disc core is not the only pain generator.
Therefore, despite the apparent attractions of only replacing the disc nucleus, here at Barcelona Spine Center we believe that the best surgical procedure in cases of lumbar and cervical degenerative disc disease is the complete replacement – or almost total replacement – of the disc and subsequent implantation of an artificial disc prosthesis.
TOTAL DISC REPLACEMENT
With total or almost total disk replacement there is excision of all potential pain causing components: the degenerated nucleus, the degenerated and cracked ring, the sinu-vertebral sensory nerve endings and the degenerated plate. Thus, the clinical outcome is usually very satisfactory, with more than 95% good results. We are also able to preserve joint movement.
It is true that many surgeons still consider arthrodesis or lumbar or cervical fusion surgery an elective surgery, however, due to the advantages and improvements in designs and materials that have taken place over the past five years, Barcelona Spine Center considers ADR surgery as the best choice in cases of cervical and lumbar degenerative disc disease, associated or not with herniated discs.
ADVANTAGES OF ADR
This is a much more physiological surgery since joint movement is preserved and therefore there are no immobilized vertebrae.
Secondly, thanks to the above, adjacent disc degeneration is prevented. When vertebral fusion is performed adjacent discs suffer degeneration, since a vertebra is immobilized the adjoining upper or lower disc suffer greater biomechanical stress. In many cases adjacent disc degeneration makes it necessary to perform further surgery in the future.
This is not so in the case of disc prostheses implants, as, by maintaining segment mobility, the lower and upper discs do not undergo degeneration.
Third, the prostheses are placed using an anterior approach. As a result, there is no need to open the back muscles, which leads to less immediate and even medium and long term postoperative pain.
Arthrodesis or fixation is usually performed with long back incisions and considerable large muscle dissection, leading to significant blood loss and muscle atrophy. For this reason, it can cause chronic pain.
Moreover, when using an anterior approach to operate on a disc there is no need to manipulate and mobilize nerves thereby considerably reducing the risk of nerve injury. Not so in fusion surgery in which the placement of implants subjects nerve structures to high risk of suffering lesions.
Fourthly, no osteotomies are performed with consequent vertebral destabilization and significant blood loss. In this surgery a degenerate worn disc is replaced by a new artificial one.
In addition, during arthrodesis osteotomies or cuts in portions of vertebrae are frequently performed to introduce implants or to achieve good bone surface fusion. It matters little that cuts are made in the vertebrae since the functional vertebral unit is fixated and becomes nonfunctioning.
BENEFITS FOR PATIENTS
Patients have a completely normal life after surgery, recovering their quality of life and even practicing sports and activities they carried out preoperatively.
The likelihood of requiring further surgery in the future is practically nil because joint movement is preserved, a fact which decreases adjacent disc disease and therefore the need for further surgery.
Finally, the cost of this type of surgery is less than that of arthrodesis or vertebral fusion, especially if you consider the early return to work.
Barcelona Spine Center is the Spanish center, and one of the best in Europe, with the greatest experience in ADR surgery, which contributes to the good statistics we have with regards to efficacy in this type of surgery, our overall risk of complications is below 3%.
This is so precisely because our experience has also meant we have achieved a decrease in the risk of vascular injury, which is one of the scariest complications. We have occasionally experienced some cases of intraoperative laceration of vascular structures but have always been able to solve this promptly.
We have also achieved satisfactory outcomes with a significant decrease in back or neck pain in 95% of cases and a high percentage of return to sporting activity. We have seen that about 70% of operated patients once more practice sports fully. Given that not all patients are athletes we can consider this result as excellent, because such a high percentage has not been achieved with any other type of spine surgery.
In this procedure they are due mainly to the route of approach. In this case as an anterior approach is used abdominal vessels are mobilized and can suffer laceration. This is a very rare complication and is easily resolved intraoperatively.
In addition the new generation of discs – better designs and materials – have eliminated complications associated with artificial discs themselves.
ADR Surgery involves a series of procedures beginning before the actual operation itself and continuing during the surgical procedure and postoperative phase. All with the aim of ensuring the best possible results for the patient.
ADR lumbar or cervical surgery, like all surgeries, involves a preliminary and detailed assessment of each case. To undergo this assessment patients should contact Barcelona Spine Center and make an appointment so as to provide our specialists with all necessary information.
Once we have received all relevant information from the patient, in approximately one week, the patient will receive our specialists’ full assessment.
Before surgery, patients must have undergone all requested tests.
Sometimes, patients have previously undergone different surgical and non-surgical treatments in order to mitigate and resolve their pain. This medical history is of interest to the surgeon before any intervention. We must also see the patient’s overall medical history, history of previous surgeries – in particular if there have been any abdominal surgeries – and current medical treatments.
Patients are admitted on the day of surgery and taken to the operating room. They must be in a fasting state for at least six hours before surgery.
Waiting prior to the surgical procedure is in a hospital room and the patient may be accompanied by friends and family. Once taken to the surgical area the patient will be briefly interviewed by the anesthetist who will require the patient to sign an informed consent regarding anesthetic risks.
Surgical time for lumbar or cervical interventions is usually about one hour. Every extra level adds about fifteen minutes.
When the operation is finished, the patient is awakened in the operating room and taken to a recovery area where he is monitored for about two hours before being transferred to a hospital room.
During the postoperative period it is normal to feel some discomfort in the area of the wound or in the cervical or lumbar area, but these discomforts disappear after a few days.
Hospital stay varies. The average patient remains hospitalized for two nights in cases of cervical arthroplasty, and three nights in cases of lumbar arthroplasty.
SIDE EFFECTS OF THE OPERATION
In some cases we have seen that some patients had residual pain or new low back pain which can be attributed to mechanical stress on the interapophyseal joints, also known as facets joints. These cases respond favorably to infiltrations or radiofrequency of the facet joints.
In our experience we have seen very few cases of subsidence of lumbar disc prosthesis. These cases have occurred in postmenopausal women over 50 years of age. That is why all patients over 50 years of age – women over 40 years of age – undergo bone densitometry testing to determine vertebral bone quality prior to surgery.
We have only experienced one case of extrusion or exit of the prosthesis which was solved by further surgery and placement of a new prostheses.
Finally, we have observed some cases of retrograde ejaculation that usually resolve over time. For this reason we advise men, especially when the L5-S1 disk is to be operated, that there is an incidence of around 0.5% retrograde ejaculation, which is usually transient.
Recovery from ADR surgery, whether it is cervical or lumbar, is a progressive recovery during which, as is normal, the patient may suffer discomfort. The patient is referred for follow-up at seven to ten days after surgery for wound dressing and removal of strips, since there are no external sutures. During the first week the patient is advised to walk and not make any efforts that will place undue strain on the operated area, and after that period to continue walking as this is the best exercise to achieve recovery.
Here at Barcelona Spine Center we do not advise the routine use of lumbar support belts after surgery. Only in some patients who notice some abdominal bloating we recommend the use of a lumbar elastic or semi-rigid girdle for a few days.
After cervical ADR we recommend that patients wear a soft cervical collar – provided in the hospital, and which can be removed to eat and sleep – until the day of the withdrawal of suture strips.
In general patients should not make efforts that will place undue strain on the operated area or adopt poor posture during the first three months after surgery, especially during the first month. Patients can start swimming a month after surgery; and jogging and cycling 3 months after surgery.
After about three weeks patients can go back to work, if this activity does not involve effort. Patients who do perform efforts that place undue strain on the operated area during work, can usually return to work 6 weeks after surgery. Alternatively, it is advisable that supervised rehabilitation sessions are carried out in a specialized physiotherapy center.
At all times, Barcelona Spine Center staff is available to patients who wish to consult or have any queries during their recovery through the usual channels, such as telephone or email.
During their hospital stay all patients are given sufficient analgesia intravenously during the first days after surgery; once they are discharged, painkilling medication is oral. Patients should take the medications prescribed at the time of discharge, which will be withdrawn gradually during subsequent visits to Barcelona Spine Center.
Medication prescribed during and after hospitalization sufficiently covers the analgesic needs of ADR cervical and lumbar surgery.
After ADR surgery, patients must perform a series of exercises.
CANDIDATES FOR ADR SURGERY
In general all patients are candidates for ADR surgery. Only elderly patients are excluded who have a degree of disc, ligament and facet degeneration that do not make this type of operation advisable.
On the other hand, this type of surgery is rare in patients under 20 years of age, because even if they have low back pain and degenerative disc disease an attempt is made to treat them conservatively.
Athletes can return to full activity and even compete after about three months.
In fact, since this type of operation has a significantly faster recovery than disc fusion and movement is preserved, athletes can return to full activity and even compete after about three months.
At Barcelona Spine Center we have seen in our series of cases as much as 70% of patients undergoing lumbar ADR return to sporting activity.
Once delivery has taken place, and after approximately six months, surgery may be performed. Furthermore a patient who undergoes ADR lumbar surgery may become pregnant a year after the intervention.
ADR lumbar surgery is not advisable in pregnant women due to the fact that an anterior approach is used. So in these cases back pain is best treated with medication.
As for cervical ADR surgery, it should only be carried out in pregnant patients in cases of extreme necessity, i.e. in cases where there is a cervical spinal cord compression.
PATIENTS WHO HAVE SUFFERED AN ACCIDENT
Patients who have suffered an accident are usually not good candidates for lumbar or cervical ADR surgery. The reason is that there is often an associated disc or ligamentous injury that results in segment instability.
LATERAL APPROACH ROUTE
The lateral approach route is a proven technique used for minimally invasive surgery of selected lumbar disc pathologies, especially for cases of arthrodesis, and recently we are also using it to replace the disc with an artificial disc (ADR). It minimizes hospital stay and the rehabilitation period. The lateral approach consists in reaching the intervertebral disc through a small incision in one side of the lumbar area.
ANTERIOR AND LATERAL APPROACHES TO THE LUMBAR SPINE
Anterior approaches to the lumbar spine consist of operating on the spine through a natural entrance that we all have in our bodies, called the retroperitoneum. Depending on the entrance point, we refer to it as an anterior approach (if we enter from the front through the belly), oblique approach (if we enter through the flank of the torso) or lateral approach (if we enter from the side). Despite choosing different entry points, they will all take us along the same pathway, or anatomical route, which is called the retroperitoneum. We will be able to reach the spine without needing to damage tissues, using special separators. The most suitable entry point for each case is chosen on the basis of the surgery, the patient, and the implant to be fitted.
The advantages of approaches of this type are:
- Non-traumatic access to the spine, without cutting tissue, since we use one of the body’s natural pathways.
- We avoid having to handle nerve structures, since the spinal canal, where they are located, is on the rear part of the spine.
- Complete excision of the damaged disc, so that it can be replaced with a disc prosthesis or fusion box.
- In the case of fusion surgery, the success rates are in excess of 95% (much higher than the classical posterior route).
- Possibility of correcting deformities with fusion boxes, without the complications of the posterior route.
- They reduce time in hospital and, hence, the rehabilitation period.
Anterior lumbar approaches are typically used to address lower levels of the spine, when, for example, we wish to fit lumbar disc prostheses or we need to perform fusion surgery with significant spinal corrections. They can also be used to improve the results of a classic posterior arthrodesis technique, since we will be performing 2 minimally invasive surgeries by fitting fusion boxes via the anterior route and then the classic screws through small incisions via the posterior route. Thus, despite the patient’s undergoing two procedures, the functional result is superior and the patient’s recovery faster.
Oblique approaches to the spine are used to access the mid-lumbar levels, between L2 and L5. With this approach, we will be able to reach the disc between a small window we find between the blood vessels running in front of the spine and the psoas muscle which covers the lateral part of the spine. This technique is used for vertebral fusion, principally with the fitting of boxes between the vertebrae, avoiding the mobilization of blood vessels. This will be the first-line technique in elderly patients, since the arteries and veins are no longer as elastic, thus avoiding complications with them.
The lateral approach to the spine is a minimally-invasive technique for the treatment of the intervertebral disc through a small incision on one side of the lower back.
We will use the completely avascular retroperitoneal route with the progressive dilation of the psoas muscle, located on the lateral part of the disc.
This allows us to treat different intervertebral disc pathologies with the fitting of fusion boxes via the lateral route.
- Degenerative lumbar disc disease in segments L1 to L5.
- Unilateral foraminal stenosis.
- Correction of deformities in the coronal plane in scoliosis surgery.
This approach will always need supplementing with posterior transpedicular screws. The advantage of fitting lateral implants lies in its not needing to handle the delicate posterior nerve structures, thus simplifying subsequent surgical procedures.
Artificial discs, either lumbar or cervical, are made of similar materials and have similar mechanical properties. However, the pressures they are subjected to are different and cause different biomechanical behavior.
ARTIFICIAL CERVICAL DISCS
It should be noted that in the cervical spine there are small joints in the back of the disc called uncovertebral joints that accompany the disc segment in lateral movements. During these movements, the center of rotation of the vertebral segment is not located in the lower vertebra but moves to the upper vertebra.
For this reason kneecap or “ball and socket” designs do not seem the most appropriate, since they do not take into account this biomechanical change that occurs in lateral movements and can therefore cause pain.
Furthermore, when the cervical vertebral segment is flexing there is translation of the articular surfaces. It is therefore important that the cervical disc prosthesis does not have a fixed center of rotation, in order to adapt to the biomechanical demands of the cervical spine.
LUMBAR ARTIFICIAL DISCS
Lumbar artificial discs support a greater load than cervical artificial discs, they have to maintain or restore a physiological lumbar curve and decrease as much as possible the load transfer to the lumbar facet joints.
In the last 10 years there has been an important evolution of lumbar artificial discs, both as to materials and design.
TYPES OF ARTIFICIAL DISCS
PRODISC – SYNTHES (for cervical and lumbar use)
The Prodisc prostheses were designed at the end of the nineties and they consist of two titanium discs finishing in one single upper and lower keel. In the middle, there is a polyurethane core with a convex upper part that fits into the hollow lower part of the upper plate. It is therefore an inverted “ball and socket” design.
M6 – SPINALKINETICS (for cervical and lumbar use)
This design is certainly innovative, the biomechanical behavior is the most similar to a natural disc. It consists of two titanium plates that are attached to the upper and lower vertebrae. In the middle, there is a core of polyurethane with a surrounding ring of polyethylene joining the two plates of titanium in the same way that the disc annulus surrounds the disc nucleus in a healthy human disk.
This prosthesis offers 6 degrees of movement, it rotates and moves in 3 spatial axes. Obviously, ball and socket designs do not achieve this, since although they can rotate and even move on their X and Y axes, they cannot move on their Z axis, i.e., they lack shock absorption capacity, a characteristic movement of disc joints.
In mechanical tests polyurethane has demonstrated stability and durability, the same can be said for the interlocking ring of polyethylene fibers.
BRYAN CERVICAL DISC – MEDTRONIC (for cervical use)
The Bryan prosthesis was the first elastomeric core to be successfully implemented and has now been extensively used for many years. Its placement must be very accurate, and it requires extensive milling of the vertebral endplates to accommodate the prosthesis which has a height of 8 mm. This prosthesis is not extensively used at Barcelona Spine Center due to these drawbacks regarding its placement.
MAVERICK – MEDTRONIC (for lumbar use)
This is a lumbar disc prosthesis consisting of two metallic discs made of a cobalt-chrome alloy. The lower half of the finished prosthesis has a domed shape which articulates with the concavity of the upper half. Published clinical results regarding the use of this prosthesis have been good and show it is a better option than lumbar fusion.
ACITV-L – AESCULAP (for lumbar use)
Activ-L, consists of three parts, two metal plates and a polyethylene nucleus. Its mechanical characteristics are very similar to those of a natural disc, i.e. it translates in flexion. The upper disc has a convex shape that adapts to the hollow form of the lower disc of the upper vertebra. The fixation system is by means of “spikes” that hook into the plate and not by means of vertebra perforating keels. Our experience with this implant has been positive.
CP-ESP (for cervical use)
Cervical disc prosthesis with improved stability due to its anatomical design, fixation by means of spikes and rough coating of pure titanium. The elastomeric cushion is made of polycarbonate urethane (PCU) and silicone, while the plates are made of titanium.
The upper plate has a convexity that adapts to the concavity usually present in the lower plate of the upper vertebra. It is the only 5 mm high elastomeric prosthesis.
LP-ESP (for lumbar use)
Lumbar disc prosthesis consisting of a central silicone core, a surrounding polycarbonate urethane ring and two titanium plates.
This prosthesis offers 6 degrees of freedom, and its good fixation features due to its spikes or tips and its rough surface coating of titanium make it possible to implant this prosthesis anteriorly as well as anterolaterally, overcoming any difficulties in vascular dissections.
This is, undoubtedly, the most constricted elastomeric prosthesis.
Cervical and lumbar ESP prostheses are the product of ten years of research, development and implantation in patients. They are designed to simulate natural spine features and are quick and easy to put in place. They offer 6 degrees of freedom, a center of adaptive rotation and shock absorbency.
For years prostheses manufacturing companies have put on the market designs that try to mimic natural discs.
In recent times, designs incorporating an elastomeric core (polyurethane, hydrogel, silicone) are those which provide a more physiological movement.
Changes have also been made to fixation systems. Initial fixation systems- some of these are still used – included fixation screws or a single high upper and lower keel. Fortunately, over time simpler and less invasive fixation systems have evolved that provide sufficient stability to the bone.
In general, implant surfaces are covered with a porous coating of plasma and hydroxyapatite which promotes bone growth on the implant. This growth comes to an end one year after surgery, for this reason we advise patients not to practice extreme sports until a year has elapsed after their operation.
By definition, any surface moving over another suffers wear in varying degrees and just like natural discs suffer degeneration this is also the case for prostheses.
However, the duration of artificial discs surpasses all the thousands of movements that a patient may perform throughout their lifetime. This prolonged duration is due to improved materials and designs, but also to the fact that spine loads are not of the same magnitude as those supported by a hip or a knee.