Stem cells, minimally invasive techniques provide patients and surgeons with alternatives to traditional spinal fusion procedures.
Managing Editor
George Weaver usually broaches the subject of belts and suspenders fairly early in the product development process. He’s not discussing fashion, though. Rather, it is Weaver’s unique way of addressing the strength and integrity of orthopedic implants.
“I just manufactured a spinal implant for a customer where the device is screwed together. The screws are strong, but with all the movement and vibration in the body—especially the back—there’s a risk that the screws could come loose. It needed a belt and suspender system,” said Weaver, vice president of marketing and co-founder of Precision Medical Products Inc., a contract manufacturer based in Denver, Pa.
“The designer said [the implant] would never come apart. I suggested that we weld the two parts together so there’s no chance the implant could ever come apart under any circumstance. Give it the belt and suspender treatment,” he continued. “I often use the ‘belt and suspender’ terminology because it’s easy to understand. It’s like wearing a belt. Sometimes, the belt can slip down under your belly, but if you have both a belt and suspenders holding your pants up they’re not going anywhere. It’s simple thinking really, but there’s a lot of common sense that goes into designing medical products.”
Particularly spinal products. Not only must they be strong and durable, spinal implants must allow for flexibility, and increasingly, possess the ability to be inserted into the body in a less invasive manner. Perhaps most importantly, however, spinal implants must be designed to treat specific conditions, whether it be degenerative disc disease, fractures, herniated discs or scoliosis.
With the tens of millions of Americans who suffer from back pain each year willing to spend tens of billions of dollars for relief, the market for spinal implants and components is ripe for growth. Indeed, statistics from international market research firm iData Research show the U.S. spinal implant market exceeding $8 billion by 2016, with the minimally invasive sector reaching more than $3 billion. In addition, rapid growth in artificial disc use is expected to fuel a six-fold increase in the spinal motion preservation market in the United States by 2016.
Globally, the spinal surgical market is expected to reach nearly $6.5 billion by 2015, a 3.4 percent compound annual growth rate (CAGR) over this year’s value of $5.5 billion, according to industry data. The nonfusion device segment is forecast to experience a CAGR of 10 percent versus 1.3 percent for fusion products, but it is not expected to constitute more than 15 percent of the total spinal surgical device market in the next five years. The nonfusion device sector, valued at $624 million in 2010, is estimated to reach $1 billion by 2015.
Vertebral repair is forecast to experience similar robust growth over the next five years due to a rapidly aging population and an increase in osteoporosis-related fractures. This sector currently is valued at $532 million but is expected to increase at a 10 percent CAGR to reach $858 million in 2015.
Some of that growth certainly will be impacted in the next few years by pricing pressure, fluctuations in patient procedure volume, Medicare and Medicaid reimbursement rates, a revamped regulatory and product approval system, and healthcare reform. Nevertheless, industry experts are optimistic about the sector’s long-term health.
“The market has grown and will continue to grow,” said Josh Sprague, vice president of Hoosier Inc., a full-service spinal contract manufacturing company based in Corona, Calif. “It’s been driven in part by baby boomers staying active for longer periods of time. We’ve become a more active society and we’re starting to wear our bodies out sooner. People now want implants and [surgical] techniques that can get them back to where they want to be sooner. They want their normal life back as quickly as possible.”
Historically, returning a sense of normalcy to someone with back pain meant fusing the spine, which essentially involved “welding” the affected vertebrae together so they healed into a single, solid bone. Devices used in this traditional treatment method include plates, screws, rods, hooks, spacers and cages made mostly of stainless steel, cobalt and titanium based alloys such as Ti-6AI-4V/ELI, Ti-6AI-7Nb, and CP Ti. However, higher strength material is available, with Carpenter Technology Corporation offering a high nitrogen, nickel-free stainless steel with strengths in excess of 200ksi and improved galling resistance. Based in Wyomissing, Pa., Carpenter Technology develops, manufactures and distributes cast/wrought and powder metal stainless steels and specialty alloys.
Though spinal fusion can be an effective technique for relieving back pain, there are drawbacks to the procedure. For starters, most spinal fusion procedures use a traditional open surgical technique to access the spine from either an anterior (front) or posterior (back) approach. Such an open technique requires surgeons to make a large incision in the patient’s abdomen or back in order to clearly see the spine and surrounding area. Invasive, lengthy and complex, these procedures often result in significant blood loss and extensive dissection of tissue, which can prolong hospital stays and complicate the recovery process. Spinal fusions also limit the range of motion in the spine.
Still, fusions remain a fairly common treatment for back pain and certain spine diseases, with more than 600,000 estimated procedures performed annually in the United States. Industry leaders expect that number to remain steady in the next few years despite the emergence and growth of other less invasive spinal repair technologies such as dynamic stabilization, artificial discs and stem cell therapy.
“As you work your way down the spine, the procedures gradually become more invasive and the devices require a tremendous amount of hardware to support the load, particularly in the lumbar region,” said Alan W. Milinazzo, CEO of Orthofix International N.V., a Netherlands-headquartered orthopedic product manufacturer with manufacturing facilities in Lewisville, Texas, and Vista, Calif. “There’s still a large unmet need for spine therapies and there will be some subsets created as the market continues to evolve. The traditional lumbar and cervical fusion therapies will always exist. But in addition to those therapies, there are motion preservation technologies, minimally invasive approaches and other areas like biologics. That’s exciting when you think about the long-term potential of the market.”
The Appeal of MIS and Motion Preservation Therapies
The long-term growth potential of the spine sector most likely will be driven by the variety of products and procedures available to surgeons and patients. Inspired by the benefits of minimally invasive surgical procedures in other areas of orthopedics, many companies have developed techniques that disturb fewer amounts of tissue in the spine.
Adopting these techniques, however, has been a slow and tedious process, hampered mostly by the limited or lack of direct access (and visibility) to the spine and the complex instruments that often are required to perform minimally invasive procedures. Many of the instruments used in these procedures require special training and the completion of numerous trial cases before the surgeon becomes proficient using the system, industry experts noted.
NuVasive Inc. has attempted to improve access to the spine by developing a minimally invasive surgical technique that does not require the dissection or retraction of back muscles, bones, ligaments or nerves. The procedure also can help reduce complications during surgery and lead to shorter hospital stays as well as quicker recovery times, according to the San Diego, Calif.-based firm.
NuVasive’s eXtreme Lateral Interbody Fusion (XLIF)approaches the spine from the side of the body. Surgeons make two small incisions—one directly over the side of the waist (through which most of the procedure is performed), and the second slightly behind the first, toward the back muscles (through which the doctor’s finger guides the approach).
An XLIF fact sheet from NuVasive claims the lateral approach to spine surgery makes it easier for doctors to remove diseased or damaged discs and insert an implant. In addition, the XLIF procedure lowers patients’ risk of vascular injury.
TranS1 Inc. has pioneered a similar inventive approach to access the lumbar spine. The AxiaLIF (Axial Lumbar Interbody Fusion) System developed by the Wilmington, N.C.-based firm features surgical instruments that help doctors stabilize the anterior lumbar column while minimizing trauma to the soft tissue in the lower back. Surgeons using AxiaLIF access the lower spine through a small opening next to the sacral bone; like NuVasive’s approach, this technique allows doctors to avoid cutting through muscles and ligaments, reducing both post-operative pain and complications. Patients typically are discharged from the hospital the day after surgery and return to work in about two weeks.
While demand for minimally invasive spinal procedures (particularly lateral fusion techniques) certainly exist, growth likely will be impacted by reimbursement rates in the near future. “Growth of the lateral fusion market will definitely be hampered by the lack of coverage from private insurers,” argued Deanna Vankessel, an analyst at Millennium Research Group, a global medical technology market research firm. “Instead of performing an XLIF, some surgeons will employ other minimally invasive approaches, such as percutaneous transforaminal or posterior techniques. However, the presence of nationwide CMS [Centers for Medicare & Medicaid Services] coverage for the XLIF and the continued release of favorable clinical data demonstrating its efficacy will curb the negative impact of these insurance providers’ decisions.”
Other newer motion preservation technologies are likely to face the same dilemma as they attempt to penetrate the market. Interspinous spacers and artificial discs are two of the more recent developments in the spinal sector that beginning to resound with both patients and surgeons.
Various designs for interspinous spacers have been developed, ranging from non-compressible metallic spacers to compressible cushion-like devices. Similar to other spinal implants, the spacers are comprised of a variety of materials, including allograft bone, titanium alloy, polyetheretherketone (PEEK) and elastomeric preparations. Though unique in detail, all interspinous spacers share a common goal: restricting painful motions while enabling otherwise normal motions. In medical jargon, the devices effect distraction between adjacent spinous processes, blocking intervertebral extension at that level.
Some of the more well-established interspinous spacers on the market include the X-Stop from Medtronic Inc., the ExtenSure from NuVasive and the Wallis Dynamic Posterior Stabilization System from Abbott Spine (now Zimmer Spine).
“A lot of our customers are designing interspinous spacers because there are some patients that don’t need spinal fusion,” Hoosier’s Sprague told Orthopedic Design & Technology. “Interspinous spacers can bridge the gap for these patients. It can give them another five or 10 years before they may need spinal fusion. Many of these interspinous [implants] are actually same-day procedures…they are quicker, less-invasive surgeries and they result in less pain for the patient. The interspinous spacers do not eliminate the need for spinal fusion—some people may still have fusion at some point down the road, but the spacers may get them through the next 15 or 20 years of their life.”
Many of the artificial disc designs that either currently are on the market or are in the final stages of development are comprised of titanium alloys, stainless steel, cobalt chromium, ceramics, PEEK or elastomer components. The discs developed by Rainier Technology Limited, for example, use a biocompatible polyurethane material with graduated modulus properties, a technology that gives the device durability and ensures the stresses generated in the implant are distributed throughout the product.
Rainier’s Cadisc-L (for the lumbar spine) and Cadisc-C (for the cervical spine) are designed to replicate the physiological biomechanics of a spinal disc. The polymeric, shock absorbing design of the Cadisc implants aims to restore the normal sharing of loads between the disc, vertebrae and other anatomical structures of a healthy spine. The British firm was awarded CE Mark approval for the Cadisc-L in September, and received $8 million in funding from two investment firms in the United Kingdom for the commercialization of the implants.
Stem Cell and Allograft Therapies
One of the newest technologies to infiltrate the spinal sector is stem cell therapy and allografts. Though adult stem cell products have commercially been available for use in spinal fusion surgery since 2005, the growth of these products has been tempered by the controversy over stem cell research as well as uncertainty over the long-term viability of these therapies and reimbursement decisions. However, the U.S. market for stem cells used in orthopedic therapy is expected to grow to an estimated $228 million by 2014, as an aging patient population looks for alternatives to invasive spinal procedures that most likely will affect their future activity levels.
Though the therapy still is in its early stages, stem cell treatments are considered by some industry experts to be an improvement over many existing techniques because of their ability to regenerate healthy tissue.
Companies such as NuVasive, Orthofix and Mesoblast Limited are the apparent pioneers in this treatment category; each company has developed a stem cell-based therapy that promotes bone growth. The companies have based their therapies on adult mesenchymal stem cells (MSCs), which “respond to their environment” and morph into a variety of cells as needed (including muscle, cartilage, fat or bone), making them an ideal alternative to autograft and other bone grafting options in which patients’ own stem cells are harvested for therapeutic use.
“The goal is to stop the degeneration of the spine and the pain in patients,” Orthofix’s Milinazzo noted. “The traditional rod and screw device implants are very invasive techniques. If you can remove the need for hardware, that is a benefit and biologics can play a big role in that.”
It can indeed. And, with the help of organizations such asAlloSource—the world’s largest producer of transplantable adult stem cells—the potential for more effective treatments of spinal diseases and conditions is a virtual slam-dunk.
Though it has spent 16 years turning tissue from donated human tissue into life-enhancing and life-saving products for others, the Centennial, Colo.-based AlloSource began using stem cells for bone growth last year with the launch of its AlloStem Stem Cell Bone Growth Substitute, which the organization describes as an adult human stem cell bone graft from adipose tissue and cancellous bone that is processed and cryopreserved into a bone graft used by surgeons. J. Kevin Cmunt, AlloSource’s executive vice president, said about half of all donated tissue is used to treat spinal conditions (with 25 percent used for the knee and the remaining 25 percent spread throughout the rest of the body).
“Biologics is where the industry is headed,” Cmunt said. “At one time in spinal fusions, the standard of care was autograft procedures. Surgeons would take a portion of a patient’s hip bone and shape it to fit the spine for fusion. But the problem with autograft is the second surgery site can be extremely painful. Many times, patients would complain more about the spot where the bone was taken. Why should surgeons do that when there’s a way to tap into the largest source of human stem cells in the human body? With the [cadaver] donations, we have all kinds of cells. In the future, there may be things we can do with nerve cells or epithelial cells. There are so many wonderful possibilities that exist.”
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Patients suffering from back pain are demanding faster recovery times and longer lasting implants. Such demands have forced orthopedic implant designers to become innovative in both the design of the devices and the techniques used to relieve pain. Innovation, however, has become scarce in the last two years as the global economic crisis suppressed demand and reimbursement rates for certain procedures fell sharply. More recently, the uncertainty over healthcare reform and the re-examination of the U.S. Food and Drug Administration’s device clearance process is discouraging many companies from designing new products and seeking regulatory approval. Despite such discouragements, market demand for spinal implants is expected to grow over the next five years as more baby boomers reach retirement age and conditions such as osteoarthritis and degenerative disc disease continue their assault on the spinal column. When the innovative ideas start flowing freely again, Precision Medical’s Weaver hopes designers will heed his advice: “Design a product that has the ability to be manufactured. When you get to the finish line, you want to have a product that’s going to work.”
Back Support
Innovation in the spine sector continues to evolve, as evidenced by these 10 new spine surgery systems which recently have been released or have received 510(k) clearance from the U.S. Food and Drug Administration (FDA):
1. S4 Cervical Occipital Plating System from Aesculap Implant Systems LLC. The FDA determined substantial equivalence for Aesculap’s S4device,designed to promote spinal fusion of the cervical and thoracic spine—vertebrae C1 through T3—and the occipito-cervico-thoracic junction—the occiput through vertebra T3—in patients with degenerative disc disease or fractures.
2. Gallery Laminoplasty Fixation System from Biomet Spine. The Gallery system features implantable plates and screws that help maintain decompression after a laminoplasty procedure and prevent the allograft from expulsion or encroaching upon the spinal cord. It is designed for use in the lower cervical and upper thoracic spine (C3-T3).
3. Parallax Contour Vertebral Augmentation Device from ArthroCare Corp. The FDA cleared the Contour device for use during kyphoplasty or vertebral augmentation procedures. The product is used to create a space in the vertebral body so it can be filled with Parallax Acrylic resin, or bone cement.
4. Kyphon Xpander II Inflatable Bone Tamp (IBT) from Medtronic Inc. The Kyphon Xpander II is the latest incantation from the creator of balloon kyphoplasty and manufacturer of the Kyphon Xpander IBT. The new IBT has an improved, pre-determined inflation pattern and exerts greater lifting force than that of the original. It also gives doctors the ability to maintain inflation of one IBT while delivering bone cement on the contralateral side of the vertebrae.
5. CHESAPEAKE Anterior-Lumbar Stabilization System from K2M Inc. An interbody device designed to stabilize the spine through an anterior approach, the CHESAPEAKE system features tifix locking technology for screw fixation; according to the company, each screw head forms an autogenic lock to the implant when inserted into the body. CHESAPEAKE is manufactured from PEEK polymer and uses an anterior insertion ramp and controlled threaded insertion while applying a zero-impact load on the interbody.
6. TiLock Pedicle Screw System from Genesys Spine. The system—designed to stabilize the spine—contains polyaxial screws (standard and cannulated) and monoaxial screws in various lengths and diameters, as well as lock plugs, cross-links, tulips and rods (also in different lengths). The system only allows the placement of 5.5-millimeter titanium rods, according to the company’s 510(k) application, though the screws can be implanted either conventionally or in a minimally invasive manner.
7. Vu aPOD Prime Anterior Lumbar Interbody Fusion from Integra LifeSciences. The Vu aPOD gives doctors two fixation options: securing it in place with two self-tapping bone screws (requiring no other steps) or using the SpinPlate internal buttress plate technology, which requires additional fixation steps. The company claims the Vu aPOD’s anatomic shape and large graft window also help to facilitate fusion.
8. Zenius Thoracolumbar Spinal System from Medyssey Co. Ltd. The Zenius System features a 5.5-millimeter titanium rod and thoracolumbar pedicle screws to help treat spinal trauma, deformities and degenerative pathologies. The system uses a dove tail joint set screw with a reverse trapezoid thread design and linear slot to improve holding strength over traditional screw sets.
9. VisuALIF Interbody Fusion Implant System from SpineSmith Partners. The VisuALIF is a two-piece, stand alone device designed for intervertebral body fusion of the lower back. According to the company, the system is the first modular lumbar interbody device with an open-face, which allows for in situ graft placement, tactile feedback with face plate attachment and device placement flush with the anterior aspect of the vertebrae.
10. STALIF MIDLINE Integrated Interbody Fusion System from Centinel Spine Inc. The system features a screw back-out prevention mechanism that includes the Lag Effect Fixation, Lumen Locking and anti back-out screw technology. The MIDLINE comes in various implant sizes to accommodate different patient anatomies as well as a new family of surgical tools designed specifically for the MIDLINE system. — M.B.