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CERVICAL SPINE SURGERY

CERVICAL SPINE UPDATE:
THE AVAILABILITY OF BIOABSORBABLE MATERIALS FOR CERVICAL SPINE SURGERY

We are pleased to announce that the FDA has approved INION'S 2-level Anterior Cervical Plate and Screw system for Anterior Cervical Spine surgery. This complements Medtronic Sofamor Danek's Bioabsorbable Intervertebral "Spacers" that have proved so reliable in our hands over the past years. For select patients this represents another major advance in the treatment of Cervical Spine Disease. This new device and the issues relating to "Anterior Cervical Fusion" surgery are reviewed in ADVANCED MATERIALS FOR SPINE SURGERY found in Sections 2 & 3 of this Cervical Spine Surgery review.


ANATOMY REVIEW

We encourage the reader to take the opportunity to review the ANATOMY OF THE SPINE on this website.

OUT-PATIENT SURGERY

In our practice, the majority of Cervical Spine surgery is carried out on a "Day Surgery" / "Out-patient" basis. All of the operations are conducted using advanced Microneurosurgical Techniques, some incorporating Minimally Invasive principles.

INDICATIONS FOR SURGERY

The indications for surgical intervention in the Cervical Region are quite specific. They are:
  1. High grade Spinal Stenosis (narrowing) resulting in significant Spinal Cord compression with or without neurological deficit. Generally, Spinal Canal diameters of 9 millimeters or less are regarded as "significant stenosis" warranting surgical consideration.

  2. Foraminal Stenosis resulting in Nerve Root injury and Neurological deficit.

  3. Neurological Deficit resulting from an Intraspinal "mass". This can be an Extruded Disc, Calcified Posterior Longitudinal Ligament, Large Bone Spur (or any combination of these) as well as Spinal Cord or Vertebral Tumors.

  4. Spinal Instability with resulting risk to Spinal Cord injury.
IMPORTANT GUIDELINES

"PAIN" IN THE ABSENCE OF NEUROLOGICAL DEFICIT SHOULD BE A RARE INDICATION FOR SURGICAL INTERVENTION SINCE ONE CANNOT NECESSARILY COORELATE THE ABNORMAL APPEARANCE ON NEUROIMAGING STUDIES WITH THE PATIENT'S PERCEPTION OF PAIN.

THE VAST MAJORITY OF PATIENTS WHO EXPERIENCE "NECK PAIN" (EVEN IN THE PRESENCE OF A "HERNIATED DISC") ARE LIKELY TO IMPROVE AND RECOVER WITHOUT ANY INTERVENTION INCLUDING SURGERY.

THOSE WHO FALL WITHIN THE "INDICATIONS FOR SURGERY" CATEGORIES IDENTIFIED ABOVE (AS WELL AS THOSE WHO FAIL CONSERVATIVE MEASURES) AND HAVE NEUROLOGICAL DEFICIT(S) CONSISTENT WITH A "LESION" AT THE APPROPRIATE ANATOMICAL LEVEL(S), MAY THEN QUALIFY FOR SURGERY.


OUR EXPERIENCE AND PRACTICE

Cervical Spine Surgery constitutes a significant portion of our practice. We are pleased to share our information and experience with some of the latest technologies, materials and advanced techniques that have considerably enhanced CERVICAL SPINE SURGERY. In most cases these surgeries are now conducted on an OUT-PATIENT BASIS.

A comprehensive Series of Monographs relating to Cervical Spine Disease and the treatment options is available to you in our Downloads & Information Section under Patient Education Library.

A. Minimally Invasive Cervical Spine Surgery

For those patients with conditions that are amenable to a Minimally Invasive approach (such as has been described in: What is Minimally Invasive and Endoscopic Neurosurgery?) we are pleased to offer this alternative. The conditions that do lend themselves to this technique include Far Lateral Extruded Cervical Intervertebral Discs, Foramenal Stenosis secondary to Cervical Facet Hypertrophy, Spinal Stenosis secondary to Hypertrophic Ligamentum Flavum as well as some Spinal Cord Tumors.

Figure 1: Post-myelographic CT Scan demonstrating a Hypertrophic Cervical Facet The patient's LEFT Foramen (represented on the RIGHT side of EACH IMAGE) is considerably narrowed (Stenotic) by the Hypertrophic Facet (Arrows indicate the diameters of the Neural Foramena.)

Minimally Invasive Resection of the Hypertrophic Facet (Same Patient as Figure 1)

Figure 2A (Left): Intraoperative Lateral Cervical Spine X-ray to show position of Minimally Invasive Retractor.

Figure 2B (Right): Minimally Invasive Retractor in position. Slender Drill is used to remove the facet.

Figure 3: Post-operative CT Scan (Same patient as Figures 1 & 2)

The Hypertrophic Facet has been removed (Arrow) using the Minimally Invasive approach demonstrated in Figures 2A & B.

B. Microsurgical Treatment of Herniated Cervical Disc and Bone Spur (Spondylosis)

The majority of Herniated (extruded) Cervical Discs are operated upon using an Anterior (front) Approach since the "herniations" (and Bone Spurs) compress the Spinal Cord and/or Nerve Root in the front of the Spinal Cord. We frequently find, at surgery, that the Herniated Disc has torn a hole in the Posterior Longitudinal Ligament at or near the center of the Spinal Canal. As part of the operation, we also routinely remove the Bone Spurs along with the Herniated Disc. The Neural Foramena, through which the Spinal Nerve Roots leave the Spinal Canal, are also opened in order to relieve any pressure on these exiting Nerve Roots. This often includes an aggressive removal of HYPERTROPHIC UNCOVERTEBRAL JOINTS (Please see Figure 5B in Cervical Spine for the Anatomical Location of the "UNCOVERTEBRAL JOINTS".) These procedures (Figures 4A & 4B) are conducted using a sophisticated Operating Microscope and a Microneurosurgical Drill in conjunction with specially designed Microneurosurgical instruments. (See Figures 7 - 11 Below for Examples of this type of surgery)

For UNCOVERTEBRAL JOINT Anatomy please refer to Figure 5B in the Previous Section

Figure 4A (Left): Operative Photo. Our Surgeons are conducting an Anterior Cervical Operation using the Leica Neurosurgical Operating Microscope.

Figure 4B (Right): Operative Photo. A Close-up view of Anterior Cervical Operation using a Microneurosurgical drill.

We specialize in the reconstruction of the Cervical Spine for complex and extensive problems such as High-Grade Spinal Stenosis (resulting from Calcified Posterior Longitudinal Ligament, large Bone Spurs and/or Migrated Extruded Disc), Bone Tumors and Instability. For those patients with conditions that warrant this type of procedure, we can routinely remove and replace entire Vertebral Bodies with highly advanced and engineered materials such as with Medtronic's Titanium "Pyramesh" Cage System. The Cage is interposed between the remaining "normal" Vertebral Bodies after the "targeted" Vertebral Bodies have been removed (Figure 5A). Once the Cage is in place, a rigid Anterior Internal Fixation Plate is attached to the FRONT of THE VERTEBRAL BODIES (Figure 5B) as part of the "Reconstruction" procedure. This is usually sufficient to support the patient which avoids the requirement for an additional operation for a "Posterior Screw & Rod Fixation System".

We use the patient's own Vertebral Body Bone, that we remove during the operation (as part of the procedure to alleviate the pressure on the Spinal Cord and Nerve Roots), to fill the Cage. This usually obviates any requirement to obtain bone from any other area of the patient nor do we generally need cadaver bone. THE TITANIUM "PYRAMESH CAGE" REMAINS PERMANENTLY IN PLACE. ULTIMATELY THE "NORMAL" VERTEBRAL BODY BONE at BOTH ENDS OF THE CAGE WILL "FUSE" WITH THE BONE THAT WAS USED TO FILL THE CAGE (see Figures 6A&B and 14A-C for additional examples.) It has been our practice to incorporate "Bone Morphogenic Protein" (BMP) within the implanted Cage which is mixed with the "harvested" Vertebral Bone that is filling the Cage. In our experience the availability of Bone Morphogenic Protein (please see the explanation in the next paragraph) has resulted in earlier, more extensive and stronger bone growth through the Cage.


Figure 5A (Above): Operative Photo. A Titanium "Pyramesh" Cage is in place between C3 & C7 after complete anterior resection (Corpectomies) of the C4, C5 and C6 Vertebral Bodies.

FIGURE 5B (Below): Operative Photo. (Same patient as Figures 5A & 6) A Titanium Anterior Internal Fixation Plate & Screws has been fixed in position (Compare to post-operative neuroimaging 6A & B).


Figure 6A (Left): Early Post-operative X-ray Anterior Multi-level Corpectomy with C3-C7 Pyramesh Titanium Cage, Plate and Titanium Screws. Anterior Internal Fixation Plate is held to the Vertebral Bodies with screws (Arrows.)

Figure 6B (Right): CT Scan (Sagittal View) at 3 months post-operative demonstrating bone growth within the Cage (the "white" material within the Cage) and from the Cage to the Vertebral Bodies on either end of the Cage (Arrow). Note: This patient has a "Fusion" at the C7T1 level.

ADVANCED MATERIALS FOR SPINE SURGERY

1. Bone Morphogenic Protein (BMP)*

One of the important long-term goals of the Anterior Cervical "Fusion" and "Cervical Spine Reconstruction" operations is early and strong bone union (fusion.) BMP is a "medication" (incorporated in the "reconstruction" process) that acts as a "bone growth accelerant" and offers considerable advantage in assisting the patient to grow bone and meet these long-term goals for Spine Stability.

Bone Morphogenic Protein 2 (which is symbolized as BMP2) belongs to a super-family called "transforming growth factor beta" (TGF-beta) and is a protein that induces the formation of bone and cartilage. "RhBMP-2" is the symbol for "recombinant human bone morphogenetic protein". RhBMP-2 has long been recognized for its remarkable potential as a bone graft substitute. In fact, BMPs are the only known proteins capable of inducing new bone formation. The first commercially available BMP ever to exhibit clinically proven osteoinductivity is the INFUSE® Bone Graft (distributed by Medtronic Sofamor-Danek Memphis, Tennessee.)

WE USE (SEE *DISCLAIMER BELOW) "rhBMP-2" IN THE "RECONSTRUCTION" PORTION OF AN "ANTERIOR CERVICAL FUSION", AS WELL AS THE MORE EXTENSIVE "ANTERIOR CORPECTOMY" (See Figures 5 & 6), OPERATIONS. WE MIX THE BMP WITH THE PATIENT’S OWN BONE (that is saved when we remove the patient's Bone Spurs at the time of operation) TO FILL THE HOLLOW CENTER OF THE INTERVERTEBRAL "SPACER" (or the reconstruction Titanium Cage) THAT IS USED TO MAINTAIN THE CRITICAL DISTANCE BETWEEN THE VERTEBRAL BODIES ("intervertebral distance") AFTER THE DISC HAS BEEN REMOVED. (Please see Section 2 A and Figures 7, 8A-E, 9A, 9E & 10 for information on Advanced Materials used for the "spacers".)

***DISCLAIMER***

The use of "rhBMP-2" for the specific purposes described in these sections is considered "OFF LABEL" since the FDA has not approved it for anything other than Anterior Lumbar Interbody Fusions and "Long Bone" implantation. THIS DOES NOT MEAN THE IT CANNOT BE USED. IT DOES MEAN THAT THE PHYSICIAN IS TAKING RESPONSIBILITY TO USE IT IN A MANNER OTHER THAN THAT FOR WHICH IT WAS EVALUATED BY THE FDA.

THERE IS CONSIDERABLE EXPERIENCE in the use of "rhBMP-2" for the specific purposes described in these sections. We are satisfied that it adds substantial benefit for our patients' more rapid and more complete recovery. For additional information concerning "off label use, please consult the following reference.

The PRIMARY GOALS of most Anterior Cervical operations are to:

  1. REMOVE THE PATHOLOGICAL CONDITION(S) (Herniated Disc and/or Bone Spurs/Calcified Posterior Longitudinal Ligament and Hypertrophic Uncovertebral Joint) responsible for the Spinal Cord and/or Nerve Root compression

  2. RESTORE NEUROLOGICAL FUNCTION & MAINTAIN STRUCTURAL STABILITY

  3. RELIEVE PAIN.
ANY "ANTERIOR CERVICAL FUSION" OPERATION REQUIRES THE REMOVAL OF THE CERVICAL DISC AT THE PATHOLOGICAL INTERVERTEBRAL DISC SPACE LEVEL(S). ONCE THE SPINAL CORD AND NERVE ROOTS HAVE BEEN SUCCESSFULLY "DECOMPRESSED", THE INTEGRITY OF THE SPINAL COLUMN MUST BE RESTORED. There are TWO (2) STEPS INVOLVED IN THIS "RESTORATION" PROCESS. (The FIRST STEP, involving the insertion of "Spacers" is reviewed in the next few paragraphs while the SECOND STEP, which involves the installation of an "Anterior Internal Fixation System", is discussed in Sections 3 & 4 Below.)

The FIRST STEP is to RECONSTITUTE THE STRUCTURAL INTEGRITY OF THE SPINE AND THE CRITICAL DISTANCE BETWEEN EACH VERTEBRA IN ORDER TO MAINTAIN THE "WINDOW" (FORAMEN) THROUGH WHICH EACH NERVE ROOT EXITS THE SPINAL CANAL. IN PATIENTS WHO UNDERGO AN "ANTERIOR CERVICAL FUSION", THIS IS ACCOMPLISHED BY INSERTING A "SPACER" TO REPLACE THE DAMAGED DISC THAT HAS BEEN REMOVED AND TO MAINTAIN THE CRITICAL INTERVERTEBRAL DISTANCE.

THE "SPACER" ALSO FACILITATES THE GROWTH OF BONE FROM ONE VERTEBRA TO THE NEXT (AT THE OPERATIVE LEVELS) AS PART OF THE ULTIMATE OPERATIVE DESIGN, WHICH IS TO "FUSE" THE VERTEBRAE TOGETHER (meaning that the adjacent Vertebrae will become a single solid unit once the bone has grown through the "spacer".)

THERE ARE SEVERAL RELIABLE DEVICES CURRENTLY AVAILABLE THAT ARE DESIGNED TO PERFORM THIS FUNCTION. WE CURRENTLY OFFER THE LATEST IN HIGHLY RELIABLE "IMPLANTS" USED TO RESTORE THE INTERVERTEBRAL BODY "SPACING". (Older techniques used a wedge of the patient's own bone (usually a piece taken from the pelvis which was a rather painful experience) as the "spacer". Cadaver bone grafts are also available for this function.)

2. MODERN INTERVERTEBRAL "SPACERS" INCLUDE:

a) BIOABSORBABLE "HYDROSORB®"

ONE OF THE LATEST MATERIALS USED AS A "SPACER" IS A "BIOABSORBABLE" "co-polymer" compound called HYDROSORB® which is a PLDLA co-polymer consisting of 70 percent Poly (L-lactide) and 30 percent Poly (D,L-lactide). THESE "SPACERS" WILL BE REPLACED BY THE PATIENT'S OWN BONE WITHIN 18 MONTHS AS IT SPONTANEOUSLY TURNS INTO WATER (H2O)AND CARBON DIOXIDE (CO2) AND DISAPPEARS. (See Figures 7, 9-13)

This "SPACER" has a HOLLOW CENTER WHICH IS FILLED WITH THE PATIENT'S OWN BONE THAT IS SAVED WHEN WE REMOVE THE PATIENT’S BONE SPURS AT THE TIME OF OPERATION AND MIXED WITH THE "BONE GROWTH ACCELERANT" (BMP) IN ORDER TO FACILITATE A MORE COMPLETE AND RAPID BONE GROWTH.

Figure 7: Operating Photo
2-level Anterior Cervical "Fusion" using Medtronic's HYDROSORB® Bioabsorbable Intervertebral "Spacers" (Arrows)

Each "Spacer" has been filled with the patient's bone (that was saved during the removal of the bone spurs) and mixed with BMP.

b) PEEK (Polyetheretherketone)

PEEK is an inert, long-lasting "plastic" substance that has been used in all manner of implants including for cardiac surgical devices. One of the "revolutionary" designs made from PEEK incorporates an intervertebral "Spacer" that is integrated with an Anterior Internal Fixation System (See Figures 8A - 8E.)

Spinal Elements, Inc. provides this integrated Intervertebral Spacer/Anterior Internal Fixation Plate System.

The Upper Plate is fixed to the C5 & C6 Vertebral Bodies. The Lower Plate is attached to the C6 & C7 Vertebral Bodies.

The Arrows point to the C6 Vertebral Body. Compare the screws in this photo to the screw positions on the X-ray (Figure 8B.)

A "PEEK" Integrated Intervertebral Spacer & Anterior Internal Fixation System at the C5, 6 and C6,7 Levels. PEEK is "radiolucent" rendering it "invisible" on X-ray. A small piece of metal within the "Spacer" identifies the posterior aspect of the implant. The Arrows indicate the placement of the "Spacers" at the C5, 6 & C6, 7 Levels. The screws are well positioned within the Vertebral Bodies.


Figure 8A (Left): Operative Photo. Mosaic™ Spinal Implant System 2 level Anterior Cervical Fusion at C5, 6 & C6, 7 (Mosaic™ Spinal Implant System by Spinal Elements, Inc. Carlsbad, California)

Figure 8B (Right): Intra-operative Lateral Cervical Spine X-ray immediately after placement of the integrated "Spacer" Anterior Internal Fixation System.

Figure 8C (Left): Medtronic's PEEK PREVAIL™ Spinal Implant System. This is an "integrated" intervertebral spacer that incorporates a "fixation" system. This is a "one-level" system. 1 level Anterior Cervical Fusion at C5,6 & C6,7
Figure 8D (Center): Operative Photo. Medtronic's PEEK PREVAIL™ Spinal Implant System in place at C5,6.
Figure 8E (Right): Post-operative Lateral Cervical Spine X-ray (Same patient as Figure 8D) after placement of the integrated PEEK PREVAIL "Spacer"/ Anterior Internal Fixation System for a 1 level Anterior Cervical Fusion at C5,6.

3. Bioabsorbable Anterior Internal Fixation Plates & Screws

Among the latest advances in Cervical Spine surgery is the adaptation of the bioreabsorbable materials for the Anterior Internal Fixation devices. These plates and screws are only available one or two-level operations since their strength is insufficient for multilevel procedures. Nevertheless, they do offer the advantage (for the appropriate patient) for the plate and screws to "disappear" in 18 months without having a permanent implant. These devices are now available from several different surgical equipment manufacturers including Inion and Medtronic.

The Medtronic Sofamor-Danek (Memphis, Tennessee) device is called the "MYSTIQUE™ Resorbable Graft Containment Plating System". It uses the same high-tech biologic co-polymer material (HYDROSORB® described in previous paragraphs) that is absorbed by the body over time, a feature not found in traditional metal implants. The MYSTIQUE™ Plate helps to stabilize the "fusion", prevent "spacer" dislodgement and facilitate healing. (See Figure 9B)

The PLATE IS SOMEWHAT FLEXIBLE and CAN BE CONTOURED TO BETTER MATCH THE PATIENT'S UNIQUE ANATOMY BEFORE INSERTION. This "HYDOSORB®" material dissolves in the body within 18 to 36 months after implantation. As the plate dissolves, its by-products, Carbon Dioxide and Water, are released through the lungs. More than 10 years of clinical experience and research have shown that implants manufactured from this co-polymer material offer a high level of surgical versatility.

Figure 9A (Left): Operative Photo of Bioabsorbable Intervertebral "Spacer".

Figure 9B (Right): Operative Photo (Same Patient) Bioabsorbable Anterior Plate & 4 Bioabsorbable Screws (Arrows).

The Inion 2-level Bioabsorbable Anterior Plate and Screw System (Figures 9 E & F) is a major new advance in our therapeutic armamentarium. This is, of necessity, more robust than the "Mystique" variety (which is restricted to a single level.) The Inion system can be used instead of a Titanium Plate and Screw system where "strength" is not a major issue such as would be required for a) short, heavy-set necks; b) patients with significant osteopenia or osteoporosis; c) patients who smoke; d) patients in whom extensive resection of one or more vertebrae is required.

An excellent example is demonstrated in Figure 9C. This 44 year old female had Left C6 and C7 nerve root deficits with spinal cord compression consequent to bone spurs, calcified Posterior Longitudinal Ligament and Bilateral Uncovertebral Joint Hypertrophy. An Anterior Cervical approach allowed for the resection of the spurs, calcified ligament and bilateral uncovertebral joints at both the C5,6 & C6,7 levels. The cervical spine required "re-contouring" (Figure 9C) in order to accommodate her reconstruction which was accomplished using 2 "Hydrosorb" bioabsorbable "spacers" (Figure 9E) augmented by an Inion 2-level anterior plate and 6 Inion bioabsorbable screws (2 in each of the C5, C6 and C7 vertebral bodies. See Figure 9F)

Figure 9C (Left): (Intra-operative x-ray with a localizing "needle" at the C5,6 interspace) Both the C5,6 & C6,7 interspaces are "collapsed" with large anterior as well as posterior bone spurs. An incidental and exceptionally rare anomaly is seen anterior to the C4,5 interspace. This "Limbus Vertebra" (Curved Arrow), a bone protuberance, is more often encountered in the lumbar spine. In this case, it was removed in order to complete the reconstruction (See figure 9D)

Figure 9D (Left Center): (Post-operative X-ray- Same patient) The small "white dots" within the vertebrae indicate the tips of the Bioabsorbable screws that were inserted. The "dots" at the upper and lower ends (Straight Arrows) indicate the upper and lower borders of the bioabsorbable plate. Notice that the anterior and posterior bone spurs have been completely removed. The anterior profile of the C5, C6 & C7 vertebral bodies have been "re-contoured". The intervertebral spaces now appear wider than "normal" since significant portions of the vertebral bodies have been resected.

Figure 9E (Top Right): (Operative Photo-Same patient as Figures 9C, D & F) The Bioabsorbable Spacers are well seated within the reconstituted intervertebral spaces. The center of the "Spacers" are filled with a combination of the patient's own bone that is preserved after removing the bone spurs from these vertebrae and a bone growth accelerant, Bone Morphogenic Protein (BMP).

Figure 9F (Bottom Right): (Operative Photo-Same patient) The Inion Bioabsorbable 2-level Plate has been contoured to the shape of this patient's spine and held in place with 6 Bioabsorbable Screws two each in the C5,C6 & C7 vertebral bodies.

Figure 10: Operative Photo. Three (3) level Anterior Cervical "Fusion" with Bioabsorbable Intervertebral "Spacers" that serve to maintain the critical distance between the adjacent Vertebral Bodies.

The center of the "Spacers" are filled with a combination of the patient's own bone that is preserved after removing the bone spurs from these vertebrae and a bone growth accelerant, Bone Morphogenic Protein (BMP).

4. Titanium Implants

A. Anterior Internal Fixation

WHERE THE BIOABSORBABLE ANTERIOR PLATE WOULD NOT BE SUFFICIENTLY ROBUST, (such as where MORE THAN ONE INTERSPACE UNDERGOES OPERATION or in most men and "larger" patients as well as in patients REQUIRING MORE COMPLEX AND EXTENSIVE "FUSION" and "RECONSTRUCTION" OPERATIONS) it is important to STABILIZE THE SPINE with a STRONGER "ANTERIOR (FRONT) INTERNAL FIXATION" DEVICE. This is a "permanent" Titanium Plate placed on the front (Anterior) aspect of the Cervical Spine and held in position with special fixation screws placed into the Cervical Vertebrae (SEE FIGURES 11, 12 & 13 BELOW). There are several reliable "plating systems" available. We currently use the latest in Aesculap USA, Inc. technology in the form of their Titanium ABC Plate and Screw System. and the "Atlantis Translational Plate" (Please see Figures 11D and 11E below.) from Medtronic Sofamor-Danek. Both of these "plates" are "load sharing" meaning that they assist in stabilizing the segments of the spine operated upon but the spine itself is the primary weight bearing and stabilizing entity which is the greatest stimulus to bone formation. A major goal of these operations is the permanent "fusion" meaning that the cervical spine segments operated upon have been permanently united by this bone growth.

Figure 11A (Left): Operative Photo. Single Level Anterior Cervical Fusion using a Bioabsorbable "Spacer" which has been filled with the patient's bone saved from the removal of their bone spurs and "BMP".

Figure 11B (Center): Operative Photo (Same Patient) Single level Aesculap ABC Anterior Internal Fixation Plate and Screws.

Figure 11 C (Right): Post-operative Lateral Cervical Spine X-ray demonstrating the "reconstruction" of the disc interspace (indicated by the Curved Arrow) by the Bioabsorbable "Spacer" (which is not visible on x-ray) and the titanium Anterior Internal Fixation Plate & Screws.

Figure 11DC (Left): Operative Photo: One level Anterior Cervical Fusion with Bioabsorbable Intervertebral Spacer.

Figure 11E (Right): Operative Photo. (Same Patient as 11D) Medtronic's Atlantis Translational Anterior Cervical Plate is held fast to the two (2) Vertebral Bodies with 2 titanium screws in each Vertebra.

Figure 11F (Left): Operative Photo. 2-level Anterior Cervical Fusion with "Spacers" well positioned to reconstitute the intervertebral height.

Figure 11 G (Below): Operative Photo (Same patient as Figures 11F & 11 H) Medtronic's Atlantis Translational Anterior Cervical Plate is held fast to the three (3) Vertebral Bodies with 2 titanium screws in each Vertebra.

Figure 11 H (Right): Post-operative X-ray (Same patient as Figures 11F & 11 G) Medtronic's Atlantis Translational Anterior Cervical Plate with screws placed in the C5,C6 & C7 vertebral bodies.


Figure 12: Operative Photo: Three level Anterior Cervical Fusion (Same Patient as Figure 10) Aesculap's ABC Anterior Cervical Plate is held fast to the Four (4) Vertebral Bodies with 2 titanium screws in each Vertebra.

Figures 13 A & B: Post-operative Lateral Cervical Spine X-rays (Same patient as Figures 10 & 12)

A (Left): 10 days post-op.
The Bioabsorbable Spacers (Arrows) are "radiolucent" (do not show up on x-ray) at this early post-op date.

B (Right): 3 months post-operative

Bioabsorbable Spacers have been largely replaced by the patient’s bone growth at 3 months post-op (Arrows).

B. Titanium Cages

There are conditions that require the removal of entire Vertebral Bodies (an operation called "ANTERIOR CORPECTOMY") such as:
  1. SPINAL CORD COMPRESSION from Extruded Discs that have migrated a considerable distance from the intervertebral space.
  2. CALCIFIED POSTERIOR LONGITUDINAL LIGAMENT that extends behind the Vertebral Body at a considerable distance for the intervertebral space and is inaccessible through the limited approach offered by an Anterior Discectomy operation.
  3. DISEASES THAT AFFECT AND/OR DESTROY THE VERTEBRAL BODY (tumors; infection; trauma) may also require the removal of the entire Vertebral Body.
WHEN AN ENTIRE VERTEBRAL BODY HAS BEEN REMOVED, IT THEN BECOMES IMPERATIVE TO "RECONSTRUCT" THE SPINAL COLUMN AND RESTORE ITS STRUCTURAL INTEGRITY.

In past years, the reconstruction portion of the operation required the use of a long bone "strut" harvested from the patient's leg (a piece of Fibula), from the Pelvis (Iliac Crest bone) or from a Rib. Cadaver bone also became available.

The availability of Titanium Cages that can be used to replace entire Vertebral Bodies has made this type of surgery faster, safer, more reliable and less painful than in the past. These "Cages" are permanent implants and can be used for single or multi-level reconstructions (See Figures 5, 6 & 14).

Figure 14A (Left): Operative Photo. Single Level (C6) Anterior Corpectomy Reconstruction using a Medtronic Sofamor-Danek Titanium Cage that has been filled with the patient's own bone (saved from the bone of the Vertebral Body that was removed during this operation) and BMP.

Figure 14B (Center): Operative Photo. (Same Patient) An Aesculap ABC Titanium Anterior Internal Fixation Plate has been installed with screws placed into the C5 and C7 Vertebral Bodies to add to the structural stability of the Spine. The Titanium Cage can be seen (through the Plate's grooves) lying behind the Internal Fixation Plate.

Figure 14C (Right): Post-operative CT Scan (Sagittal View-Same Patient.) The Spinal Alignment and Structural Integrity has been re-established using the Anterior Internal Fixation Plate & Screws and the Titanium Cage.

5. Cervical Spine "Replacement" Discs (CERVICAL DISC ARTHROPLASTY)

"BEST PRACTICES"

For many years, and even at the present time for most patients, the "best" form of surgical therapy for Herniated Disc and/or Degenerative Cervical Osteoarthritis (Spurs/Calcified Posterior Longitudinal Ligament and Hypertrophic Uncovertebral Joints) that result (either alone or in combination) in significant Spinal Cord or Nerve Root compression, comprises some form of Anterior Cervical Spine operation for removal of the offending pathology followed by an immobilization (fusion) of the diseased joint(s).

One of the THEORETICAL DISADVANTAGES of this "fusion" is the transference of “motion” and the forces of that motion to the immediately adjacent joints which may result in an acceleration of progressive degenerative changes (bone spurs) at those adjacent Disc Space levels. Recent Neurosurgical and Orthopedic professional publications have paid considerable attention to this issue (under the newly minted term, "Adjacent Level Disease"). While the actual risk, in our considerable experience, is exceptionally low, there is some truth to the concept.

CERVICAL "MOTION PRESERVATION"

Cervical Spine "motion preservation" is the theoretical concept underlying the development of "Cervical Spine Replacement Discs". The "artificial discs" have been designed to hopefully, reduce the risk for the progression of Spondylosis at the adjacent levels by preserving Cervical Spine motion. These devices are, in fact, definitely not "disc" material, but rather are surgical implants made of one or several durable materials such as advanced polymers and/or metallurgical materials. The first of these new devices became available in mid-July 2007. Currently there are other similar technologies (Figure 18), created by several different commercial enterprises, in various "clinical trial" phases or awaiting FDA approval. THESE OTHER DEVICES ARE AVAILABLE ONLY ON AN EXPERIMENTAL BASIS. This includes the "Bryan" Disc (Figures 15 & 16) and "PRODISC-C®" (manufactured by SYNTHES, Inc. - Figure 17) among others.

Figure 15 A&B: Post-operative x-ray. A two (2)-level "disc replacement" operation has been carried out using the "BRYAN" artificial discs at the C5-6 & C6-7levels. Figure 15 A (Left) is a Lateral Cervical Spine X-ray with the neck flexed forward and Figure 15 B (Right) has been taken with the neck in extension. The "motion" at these 2 Vertebral Disc spaces has been "preserved" as seen by the change in Anterior (Front) portion of the "Artificial Disc" in these two positions.

Figure 16A (Left): "Bryan" Artificial Disc. A Vertically Oriented Diagram demonstrating some of the component parts of this complex structure.

Figure 16B (Center): "Bryan" Artificial Disc 3/4 Profile View. The Anterior part of the device (Arrow) is where it is "anchored" to the Front of the Vertebrae.

Figure 16C (Right): "Exploded" Diagram demonstrating how the "Bryan" Artificial Disc is "seated" between the vertebrae in custom crafted troughs (Curved Arrow) created by a special "jig".

Figure 17A (Left): Post-operative X-ray (Lateral View) A "PRODISC-C®" Artificial Disc (SYNTHES, Inc.) has been inserted at the C5,6 level.

Figure 17B (Center-Left): Post-operative X-ray (Antero-posterior View-Same Patient) of the "PRODISC-C®" at the C5,6 level.

Figure 17C (Center-Left): Anatomical Model demonstrating the position of the PRODISC-C® Artificial Disc in the disc space. (Compare this to the Post-op X-ray image in Figure 17B.)

Figure 17D (Right): Photo of the "PRODISC-C®" Artificial Cervical Disc

Emerging Scientific Studies

Several scientific reports regarding "Artificial Cervical Joint Devices" have become available. One such initial "long term follow-up" for "Artificial Disc Implantation" was reported at the American Association of Neurological Surgeons Annual Meeting held in San Francisco on 26 April 2006. The report was based upon a European Multi-center Study that was tabulated in Leuven, Belgium and consisted of 67 patients, some of whom have been monitored for up to 9 years. The authors identified several unanticipated consequences of the "artificial disc" that was used in this study (the "Bryan"-type device shown in Figures 15 & 16 above.) Whereas it was hoped that progression of Spondylosis (Bone Spur formation) at the adjacent Cervical Levels would be markedly reduced, if not aborted entirely, in actual fact there was progression of the Spondylosis at the adjacent level(s) in 20 of 38 patients (52.6%).

It appears that the device designers and manufacturers, have underestimated the likelihood of significant PROGRESSION of DEGENERATIVE SPONDYLOSIS (BONE Spurs) AT THE OPERATED LEVEL(S) as well as impressive progression of paravertebral calcification (calcification in the "Lateral Longitudinal Ligaments" and the "Uncovertebral Joints" that are positioned on either side of each Vertebra) in 22.4% of these patients. (For information on "Uncovertebral Joints" see Figure 5B of the previous Section)

In fact, once one understands the underlying pathological anatomy and the progressive nature of the Degenerative process, it becomes clear that MOTION IS, IN PART, THE SOURCE OF THE DEGENERATIVE ARTHRITIC CHANGES. Therefore IF A PATIENT ALREADY HAS DEGENERATIVE ARTHRITIS AT THE "ADJACENT LEVEL(S)", ONE WOULD EXPECT THE NATURAL PROGRESSION OF THAT DISEASE PROCESS (at the "adjacent levels") WHETHER OR NOT MOTION IS "PRESERVED" AT THE OPERATED LEVEL.

IN A SIMILAR WAY, IF THERE IS ANY "ARTHRITIS" REMAINING AT THE OPERATED LEVEL (SUCH AS POSTERIOR SPURS AND/OR HYPERTROPHIC UNCOVERTEBRAL JOINTS), THEN THE "PRESERVATION OF MOTION" WILL UNDOUBTEDLY RESULT IN PROGRESSION OF BONE SPUR GROWTH AT THE OPERATIVE LEVEL. IT IS, THEREFORE, HIGHLY LIKELY IN OPERATIVE CASES WHERE THERE IS "PRESERVATION OF MOTION", THAT THERE WILL BE PROGRESSSION OF THE UNRELIEVED SPINAL AND/OR FORAMENAL STENOSIS IF THE SURGEON FAILS TO REMOVE THE SOURCE(S) OF THIS NARROWING.

IN OTHER WORDS, IT IS IMPERATIVE FOR THE SURGEON TO RECOGNIZE THAT ANY PRE-EXISITING DEGENERATIVE (HYPERTROPHIC) UNCOVERTEBRAL JOINT ARTHRITIS MUST BE REMOVED AT THE TIME OF "CERVICAL ARTHROPLASTY". Pre-existing Hypertrophic Cervical FACET JOINT Arthritis would be expected to progress and worsen at any level where motion is "preserved".

OUR CURRENT OPINION

There are certain important issues that these "substitute joint systems" can theoretically address.

In our opinion THESE DEVICES WILL PROBABLY BE BEST USED FOR PATIENTS WHO ARE UNDERGOING AN ANTERIOR CERVICAL DISCECTOMY FOR A HERNIATED INTERVERTEBRAL DISC AND DO NOT HAVE SIGNIFICANT DEGENERATIVE HYPERTROPHIC UNCOVERTEBRAL JOINTS, MORE EXTENSIVE POSTERIOR SPONDOLYTIC "SPURS" AND/OR CALCIFIED POSTERIOR LONGITUDINAL LIGAMENT AND DO HAVE A REASONABLY WELL PRESERVED INTERVERTEBRAL DISTANCE ALL AT THE PROPOSED OPERATIVE LEVEL.

FOR PATIENTS WHO DO HAVE ADVANCED DEGENERATIVE ARTHRITIS, THE "PRESERVATION" OF MOTION AT THE OPERATIVE DISC SPACE MAY ACTUALLY RESULT IN MORE EXTENSIVE AND MORE RAPID DETERIORATION AT THE OPERATED JOINT LEVEL AS WELL AS THE ADJACENT JOINT SPACES.

Figure 18: A montage of some of the current "Artificial Disc" devices under investigation at this time.

THE "PRESTIGE®" "ARTIFICIAL CERVICAL JOINT" DEVICE

The Medtronic Sofamor Danek Company received FDA approval for implantation of the "PRESTIGE®" Cervical Joint Device in mid-July 2007. This Stainless Steel device has gone through multiple developmental stages since 1991. THE CURRENT MODEL MOST CLOSELY REPRODUCES THE NORMAL MOTION AT THE DISC SPACE LEVEL INCLUDING THE "SLIDING" MOTION ASSOCIATED WITH THE FACET JOINTS AT THAT LEVEL.

THE OPERATION TO IMPLANT THIS DEVICE is called "CERVICAL DISC ARTHROPLASTY". An important scientific clinical study was recently reported concerning the results in 276 patients undergoing Cervical Arthroplasty using the "PRESTIGE®" "ARTIFICIAL CERVICAL JOINT" followed for up to 2 years (October 2002-August 2004) and COMPARED TO "MATCHED PATIENTS" UNDERGOING SINGLE LEVEL ANTERIOR CERVICAL FUSION. For those patients in whom this "PRESTIGE®" Cervical Joint Device was implanted, the study suggested a favorable clinical outcome compared to a similar number of patients who underwent a more standard "Anterior Cervical Fusion". Although this comprises a relatively small group of patients followed for a short time, the results are significant. A video relating to this device is available online.

Figure 19A (Left): 3/4 Profile Photo of the "PRESTIGE®" Cervical Joint Device.

Figure 19B (Center): "PRESTIGE®" Cervical Joint Device (Side View)

Figure 19C (Right): Diagram of the "PRESTIGE®" Cervical Joint Device (Anterior View of the Cervical Spine)

This is a Stainless Steel "Ball & Trough" system that is placed in between two adjacent Cervical Vertebrae AFTER THE DISC HAS BEEN REMOVED. The current version requires the surgeon to fix the new "joint" in position with screws placed into the Vertebral Body.

Figure 20A (Left): MRI Scan (Sagittal View) demonstrating a Herniated Cervical Disc (Arrow).

Figure 20B (Right): MRI Scan (Axial View) The Herniated Disc at the C5, 6 level (Curved Arrow) is compressing the Spinal Cord on the Right as well as the Nerve Root exiting the Spinal Canal at this level. While there are small bone spurs at this level, they can be removed at the time of surgery along with the Herniated Disc.

Figure 21 (Left): Post-operative X-ray (Lateral View) in "neutral" position demonstrating the "PRESTIGE®" Cervical Joint Device in place.

WHO MAY QUALIFY FOR "CERVICAL DISC ARTHROPLASTY"?

The "PRESTIGE®" Cervical Joint Device IS APPROVED FOR ONLY ONE (1) CERVICAL LEVEL in PATIENTS WHO ARE 18 YEARS OR OLDER AND HAVE ACHIEVED "SKELETAL" (BONE) MATURITY and WHO ARE NOT PREGNANT or NURSING AN INFANT AT THE TIME OF SURGERY.

THESE PATIENTS HAVE A CERVICAL RADICULOPATHY (NERVE ROOT INJURY) AND/OR MYELOPATHY (SPINAL CORD INJURY) RESULTING FROM A HERNIATED DISC AND/OR SPONDYLOSIS (BONE SPUR FORMATION) AT A SINGLE LEVEL WHERE THE DISC SPACE HEIGHT IS REASONABLY PRESERVED.

WHAT ARE THE CONTRA-INDICATIONS TO "CERVICAL DISC ARTHROPLASTY"?

THIS DEVICE CANNOT BE USED IN PATIENTS WHERE THERE IS:
  1. INFECTION
  2. LOCAL INFLAMMATION
  3. SEGMENTAL INSTABILITY (ABNORMAL MOTION AT THE CERVICAL LEVEL BEING CONSIDERED FOR "ARTHROPLASTY")
  4. MORBID OBESITY
  5. PREGNANCY
  6. MENTAL ILLNESS OF INCOMPETENCY
  7. DOCUMENTED (OR SUSPECTED) METAL ALLERGY OR INTOLERANCE
  8. RAPIDLY ADVANCING BONE DISEASE, BONE ABSORPTION, OSTEOPENIA OR OSTEOPOROSIS
  9. KNOWN HEREDITARY OR ACQUIRED BONE FRIABILITY OR CALCIFICATION PROBLEMS
  10. IMMATURE GENERAL SKELETAL GROWTH (PEDIATRIC-TYPE)
  11. METABOLIC BONE DISEASE OR SEVERE OSTEOMALACIA
  12. CERVICAL SPINE TUMOR, CERVICAL SPINE INFECTION, CERVICAL SPINE CONGENITAL ANOMALIES, LOCAL OPERATING SITE FRACTURE, ELEVATED SEDIMENTATION RATE OR MARKED "LEFT SHIFT" IN THE WBC (WHITE BLOOD CELL) "DIFFERENTIAL COUNT" (This latter finding would indicate an "inflammatory" condition or infection.)

ADDITIONAL INFORMATION

For additional information and/or to determine who qualifies for any of these procedures, please CONTACT OUR OFFICE. This website also offers Cervical Spine Disease monographs which you may download at your convenience.

DISCLAIMER: Every effort has been made by the author(s) to provide accurate and up-to-date information. However, the medical knowledge base is dynamic and errors can occur. By using the information contained herein, the viewer willingly assumes all risks in connection with such use. Neither the author nor Neurosurgical Consultants, p.a. shall be held responsible for errors, omissions in information herein nor liable for any special, consequential, or exemplary damages resulting, in whole or in part, from any viewer(s)' use of or reliance upon, this material.

CLINICAL DISCLAIMER: Clinical information is provided for educational purposes and not as a medical or professional service. Person(s) who are not medical professionals should have clinical information reviewed and interpreted or applied only by the appropriate health professional(s).

OFF-LABEL DRUG USE: The off-label use of FDA-approved drugs is not regulated, but it is entirely legal in the United States as well as many other countries. The FDA does not regulate the practice of medicine. This means that once the FDA approves a treatment, licensed physicians can prescribe it for any purpose they consider medically appropriate. Off-label use can vary greatly from one doctor to another, and depends on the doctor's preferences, knowledge, and past patient experiences. The medical literature reports clinical trials, including those that are not part of the FDA approval process. This is the main source of off-label use information, but treatment guidelines may also offer options that include off-label use. Treatment guidelines are based on information from medical literature, including clinical trials, and explain recommended ways of treating a particular illness. Lack of information on off-label drug use and outcomes may put patients at a higher risk for medication errors and unwanted drug reactions.


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This page last edited on 2/19

All content ©2016 by Neurosurgical Consultants, P.A.
Author, Martin L. Lazar, MD, FACS
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