BB&T Contributing Writer
BERLIN — The 7th annual Global Symposium of Motion Preservation Technology, sponsored by the Spinal Arthroplasty Society (Aurora, Illinois), held in early May, drew 1,600 attendees to a program that featured many workshops and presentations that produced a clear theme for the symposium and what this sector is increasingly fo-cused on — the avoidance of spinal fusion.
The spinal fu-sion proceudure has been a somewhat tarnished form of the usual “gold standard” delineation in medical care, since the fusing of vertebrae tends to reduce flexibility and range of motion and usually involves lengthy recovery and rehabilitation, thus driving the search for alternatives.
The presentations and company offerings thus featured a broad and interesting panoply of alternatives to fusion, such as artificial discs, nucleus replacements, facet replacement devices, dynamic stabilization systems and interspinous devices.
One indication of the society’s growing presence was the landmark issuance of the inaugural publication of its new peer-reviewed publication, SAS Journal. But even more impressive is the increasing economic status of what was previously only a niche market. The spine fusion market in the U.S. is estimated at approaching $4 billion in the U.S., motion preservation represents the largest growth opportunity in the spinal implant market overall.
Given these large opportunities, the spinal products arena has become crowded with an increasing number of U.S. and European companies competing with a variety of designs for motion preservation products. Many of the devices that were displayed at the symposium are approved for sale only outside the U.S., mainly in Europe, and were the subject of ongoing clinical trials in anticipation of future entry into the U.S. market.
Rather than fusing discs there is an increasing emphasis on replacing or replacing these materials that serve as cushions between the vertebrae. There are currently two lumbar artificial disc replacement products sold in the U.S.: the Charit from DePuy Spine (Raynham, Massachusetts), and the Prodisc from Synthes Spine (West Chester, Pennsylvania).
Cervical artificial disc replacement products are not yet approved for sale in the U.S., though they are commercialized in Europe by several companies. About a dozen companies are pursuing the U.S. market opportunity for these devices, with products in clinical trials.
The first artificial cervical disc expected to receive FDA clearance is the Prestige LP, from Medtronic Sofamor Danek (Memphis), which is in an investigational device exemption clinical trial. Medtronic is also developing the Bryan cervical disc.
Cervitech (Rockaway, New Jersey) featured its PCM (Porous Coated Motion) artificial cervical disc, a motion-retaining cervical intervertebral replacement disc prosthesis with a metal- (cobalt chrome) on-UHMW polyethylene design and a titanium calcium phosphate surface coating for bone integration. Fixation to the vertebrae above and below the disc space is achieved with a press fit to the teeth and ridges of the implant. It is about 80% through an IDE clinical trial.
Cervitech sells a line of cervical discs in Europe for varied indications. Its PCM-V artificial cervical disc is sold in 28 countries. The company has no product sales in the U.S.
SpinalMotion (Mountain View, California) is focused exclusively on spinal disc arthroplasty. Its Kineflex lumbar and KineflexC cervical discs are metal-on-metal and have a semi-constrained mobile center of rotation. Single and multi-level disc replacements with the Kineflex artificial discs have been performed internationally for over four years. Both discs are being sold in South Africa.
The company is currently conducting two IDE clinical studies in the U.S. The Kineflex lumbar disc study is completely enrolled at 20 sites, and the KineflexC cervical disc is near completion at 23 sites. A published paper recently reported long-term data from outside the U.S. on the first 100 lumbar disc patients and near completion of enrollment in the U.S. cervical trial. Published results reported that 95% of disc implants were radiologically in the ideal position, post-operative hospitalization averaging 2.8 days, and all patients employed before surgery returning to work an average of 31 days after surgery.
Pioneer Surgical Technology (Marquette, Michigan) has the CE mark for its Nubac disc arthroplasty system which its sells in Europe. It is in an IDE clinical study in the U.S. from which there are early clinical results with two-year follow up.
Its PEEK-on-PEEK construction minimizes wear and was the subject of a poster presentation. The Nubac disc has an articulating disc design that is tissue-sparing and preserves natural biomechanical functions, and is a less invasive alternative to total disc arthroplasty and fusion. It is implanted by a unilateral posterior approach. Pioneer markets in the U.S. a full line of spinal products including pedicle screws for fixation, spinal spacers, vertebral body replacement devices and the Quantum spinal rod system.
Replacing the nucleus
Rather than replacing the entire disc, an alternative approach is replacing the disc nucleus.
Raymedica (Minneapolis) and Paradigm Spine (New York), along with Small Bone Innovations (New York), are all 40%-45% owned by Viscogliosi Brothers (New York) and are headed by family members. Raymedica is conducting an investigational device exemption pilot study in the U.S. on HydraFlex, its latest-generation nucleus replacement. It has the CE mark.
Raymedica’s PDN-SOLO prosthetic disc nucleus device is the first commercial nucleus replacement product. Compared to PDN-SOLO, the HydraFlex product is softer, has an increased hydration rate and is a contoured device to more closely approximate the natural anatomy. It expands into a larger footprint and has strong load-bearing characteristics. It also is used with new instrumentation and a different surgical procedure.
At the SAS symposium, Raymedica distributed several volumes of reports entitled “Nucleus Arthroplasty in Spinal Care” that reviewed surgical techniques, technologies and biomechanics.
Nucleus replacement products being developed by other companies include the NeuDisc, an anisotropic synthetic hydrogel from Replication Medical (Cranbury, New Jersey); Dascor, a polyurethane polymer from Disc Dynamics (Eden Prairie, Minnesota); NuCore, a protein-based material from Spine Wave (Shelton, Connecticut); PNR (Percutaneous Nucleus Replacement), an in situ curing silicone from TranS1 (Wilmington, North Carolina); and BioDisc, an in situ polymerizing protein hydrogel from CryoLife (Kennesaw, Georgia/Guilford, UK).
Alternative stabilization to preserve motion
Dynamic stabilization and interspinous devices provide pain relief by off-loading the discs and providing hyper-extension of the spine.
Impliant (Princeton, New Jersey/Ramat Poleg, Israel) featured its Total Posterior Motion Preservation (TOPS) system, an alternative to spinal fusion. It is comprised of titanium plates and an articulating polyurethane construct. TOPS is a mobile posterior device. It is used to stabilize but not fuse the affected vertebral levels in patients suffering from debilitating leg and back pain stemming from moderate to severe spinal stenosis that also may be accompanied by facet arthrosis and degenerative spondylolisthesis.
The device is used for posterior arthroplasty at two adjacent levels in patients and is attached to the spine using six pedicle screws. The company reported positive results on 32 patients with the longest follow-up to date being two years.
The TOPS system is being evaluated in 10 clinical trials underway in South Africa, Belgium and Turkey. It has the CE mark.
Scient’x (Guyancourt, France/Maitland, Florida) was founded in 1987 and has established its presence as a marketer of dynamic stabilization and motion preservation spinal implants. Its IsoBar TTL product has been implanted in more than 14,000 spinal fusion patients worldwide. Scient’x was the first company to launch pure PEEK cages, although the preference in Europe is for metal products. Its Discocerv ceramic bearing cervical disc is sold outside the U.S.
Applied Spine Technologies (New Haven, Connecticut) recently received CE-mark approval for Stabilimax NZ Dynamic, a posterior dynamic spine stabilization system designed to support an injured or degenerated spine. It requires no tissue removal or replacement and is a less invasive option for patients who would otherwise be candidates for fusion or artificial disc implants.
A 400-patient, 20-site IDE trial has begun which will compare posterior dynamic stabilization using Stabilimax NZ to patients receiving traditional fusion stabilization to treat degenerative lumbar spinal stenosis. The initial test sites are Triangle Orthopaedic Associates and North Carolina Specialty Hospital (Durham, North Carolina). The company had previously received FDA 510(k) clearance as well as the CE mark for its Stabilimax BAR for treatment of degenerative lumbar disease.
Paradigm Spine received the CE mark for its DSS (dynamic spine stabilization) system, a pedicle screw-based implantable system indicated for degenerative disc disease of the lumbar spine. It combines elements of fusion and motion preservation. It is considered a truly dynamic stabilization system because it increases segmental stiffness while controlling specific ranges of motion. The posterior segmental height can be adjusted by selecting the appropriate size dynamic coupler.
The system was developed in collaboration with Hans-Joachim Wilke, a professor of biomechanics at the University of Ulm (Ulm, Germany) and Rudolf Bertagnoli, MD, a leading motion preservation spine surgeon in Straubing, Germany. The DSS is Paradigm Spine’s fourth product to receive CE-marking, following the coflex functionally dynamic interspinous implant for the treatment of lumbar spine stenosis, the coflex-F implant system for degenerative disc disease and the DCI dynamic cervical implant. The devices are being sold in Europe.
The coflex device is in a 450-patient study, at 20 sites in the U.S., expected to be completed in 2008. It is being compared with pedicle screw fusion, the current standard-of-care. It is a U-shaped titanium alloy surgical implant indicated for use in patients with moderate to severe spinal stenosis. The company expects to receive the CE mark later this year for Orthobion, a non-fusion system for treating scoliosis in children 8-17 years old.
The X-Stop IPD (Interspinous Process Decompression) spacer which came with the acquisition earlier this year of St. Francis Medical Technologies (Concord, California) by Kyphon (Sunnyvale, California) has gained acceptance as an alternative to the Dynesys device for spine stabilization.
Ulrich (Chesterfield, Missouri/Ulm, Germany) markets a broad line of implants and instruments for anterior and posterior stabilization of the whole spine. Its products are sold in 60 countries and include the Topaz anterior distractable cage, Heliodor PLIF cage, MDS mini disc spacer, Osmium anterior cervical plate system, and Neon superior spine system. Devices for the posterior thoracic and lumbar spine are the Krypton multi-segmental spine fixator, Cosmic posterior dynamic system, TangoRS cannulated polyaxial pedicle screws, and Obelisc vertebral replacement device.
Working in the lumbar region
TranS1 has pursued a trans-sacral approach to lumbar surgery. Its AxiaLF is a percutaneous access and fusion system. It was launched in Europe and the company has submitted an FDA 510(k) application in the U.S. The device enables lumbar fusion to be performed with complete preservation of the disc annulus and all paraspinal soft tissue structures. The company is also developing a percutaneous disc replacement (PDR) for delivery through the trans-sacral approach.
Ranier Technology (Cambridge, UK) is in preclinical trials with CAdisc-L, a fully compliant artificial lumbar disc prosthesis with polyurethane elastomer endplates and an osseo-conductive surface coating of calcium phosphate for rapid and long-term attachment to bone. It is MRI- and X-ray compatible and has a proprietary graduated modulus design which has the functionality of the natural disc for optimized biomechanical performance. It also uses a graduated modulus design for its cervical disc, CAdisc-C.
DePuy Spine (Raynham, Massachusetts) recently introduced in the U.S. its AEGIS anterior lumbar plate system designed to treat degenerative conditions of the lumbar spine. It has a semi-rigid design that allows for load-sharing between the construct and the bone graft, reducing the risk of screw breakage and encouraging fusion.
The company also launched the ExpediumFX cross connector system designed to make cross connector implantation quicker, easier and more secure at the completion of spinal surgery. It is available in fixed and adjustable length configurations and offers a “snap-fit” feature that provides surgeons with audible and tactile feedback to confirm that the connector is securely attached to the rod. The company markets the Discover cervical artificial disc outside the U.S.
Alphatec Spine (Carlsbad, California) markets pedicle screws, cervical plates, spinal spacers, anterior and lumbar interbody fusion (ALIF and PLIF) devices fabricated in PEEK and titanium. Alphtec is one of three publicly traded companies that specialize in spinal products, the others being NuVasive (San Diego) and Kyphon (Sunnyvale, California).
Alphatec licensed from Scient’x the ALIF cage system with a securitized anterior PEEK plate to prevent implant migration and the Dynamo Dynamic Rod, a pre-contoured rod for lordosis available in lengths from 65 mm to 400 mm that allows for load sharing between the vertebral body and the endplates.
Completion of a 510(k) submission is required for use of the rod with its screw system and the company expects to introduce the product later this year. It also licensed from Scient’x an ALIF cage system with a securitized anterior PEEK plate to prevent implant migration
Zimmer Spine (Minneapolis/Winterthur, Switzerland) featured its leading Dynesys, a pedicle screw-based lumbar spine stabilization system that has been used in 30,000 patients. It uses flexible materials to stabilize the affected lumbar spine while preserving the natural anatomy of the spine and is indicated for use as an adjunct to spinal fusion. An IDE clinical study is underway for non-fusion applications.
Zimmer Spine markets a broad line of products for use in spinal surgery, including Trinica anterior cervical plates, Dynardi dynamic artificial disc system, several spinal fixation systems, CopiOs bone void filler and trabecular metal ALIF devices.
Zimmer recently acquired Endius (Plainville, Massachusetts), a marketer of minimally invasive devices for spine surgery. Its key products include the Atavi atraumatic spine surgery system, designed with an Oval FlexPosure retractor for lumbar spine visualization, the newly introduced NexPosure for cervical spine visualization, TiTLE 2 polyaxial pedicle screw system, NorthStar cannulated screw delivery system, TriFix spinal instrumentation system, and the Minit upper thoracic fixation and posterior cervical system.
The percutaneous approach
A report issued by Millennium Research Group (Waltham, Massachusetts) entitled “U.S. Markets for Minimally Invasive Spinal Fusion Technologies 2007,” sets the current size of this MIS market at $345 million with a compound annual growth rate of 28% compound resulting in an over $1 billion market by 2011.
Interventional Spine (Irvine, California) develops and markets implantable spinal devices that can be deployed via percutaneous techniques. Its Perpos system is a complete set of instruments engineered for percutaneous implantation of its one-size-fits-all Bone-Lok implant.
It has a 510(k) approval. Percudyn, for percutaneous dynamic stabilization via bilateral extension of the facet joints, is not yet approved for marketing in the U.S.
Globus Medical (Audubon, Pennsylvania) claims to be the first company to introduce a total disc replacement device for implantation using a minimally invasive posterior approach. The device has two halves that work in unison to achieve the required range of motion.
It is implanted using a procedure that entails a three-inch incision and transforaminal approach which minimizes the need for muscle dissection and retraction. The patients are discharged the day after surgery. Full recovery is expected in three to six weeks, according to Paul McAfee, MD, chief of spinal surgery at St. Joseph’s Medical Center (Towson, Maryland).
Globus calls itself the largest privately held spinal implant mnaufacturer, with more than $100 million in annual revenues. Its recent product introductions are the Gateway thoraco-lumbar stabilization plat and the XPand-R radioucent copectomy spacer. The company says it plans to conduct trials this year under an dIDE for the Flexus Non-fusion interspinous spacer device. Globus markets its products in the U.S. and India and it hs reported plans to enter the Euroopean market this year.
IST Spine (Mansfield, Massachusetts) markets the Paramount pedicle screw for minimally invasive spinal fusion and the VBR system that is made from PEEK-Optima. It is delivered on a steerable inserter that maintains control over the implant during all phases of insertion and removal.
The company also has under development an anterior cervical plate, a mini-open retractor, and a dynamic fixation device to reduce stress at the bone screw interface Enrollment in a pivotal study of a full-motion dynamic stabilization device will be initiated in 2008.