BBI Washington Editor

WASHINGTON Minimally invasive. "That's the buzzword," said Courtney Brown, MD, assistant clinical professor of orthopedic surgery at the University of Colorado Health Sciences Center (Denver) and an orthopedic surgeon at Panorama Orthopedics (Golden, Colorado). Much of what was being presented at the late-February annual meeting of the American Academy of Orthopaedic Surgeons (AAOS; Rosemont, Illinois) was focused on innovative treatments to get patients back on their feet sooner, with the least amount of intervention and pain. Courtney, along with Paul McAfee, MD, orthopedic surgeon at the Scoliosis and Spine Center (Towson, Maryland) and Jeffrey Wang, chief of orthopedic spine service and associate professor of orthopedic and neurosurgery at UCLA Comprehensive Spine Center at the UCLA School of Medicine (Los Angeles), discussed emerging technologies in spinal surgery.

Overall, the standard of treatment for degenerative spinal disorders such as slipped discs or compression fractures is non-operative are. Some patients, however, require surgical procedures that could include spinal fusion, injection of cement into the weakened vertebrae, or the placement of screws and metal plates to stabilize the spine.

Disc replacement a procedure where the injured disc and replaced with an artificial one has emerged as an alternative to fusion, offering some patients less post-operative pain, fewer complications and faster recovery, McAfee said.

McAfee participated in the trials focusing on replacement in the lumbar region using the Charit disc manufactured by the DePuy Spine (Raynham, Massachusetts) division of Johnson & Johnson (New Brunswick, New Jersey). Approved by the FDA last October, Charit is the first product cleared for this indication in the U.S. It has been approved for use in Europe for more then a decade.

The FDA cleared the disc for patients with degenerative disc disease in the lower spine who have had no pain relief despite at least six months of non-surgical treatment. DePuy has estimated that use of the Charit or any other artificial disc might replace from 15% to 35% of fusion procedures.

Other companies working on replacement disc technology for neck and back include Medtronic (Minneapolis), Raymedica (Minneapolis), Stryker (Kalamazoo, Michigan) and Replication Medical (New Brunswick, New Jersey).

McAfee said FDA approval of another similar device is still "a little ways off."

"The great thing about disc replacements is that they allow us to preserve motion in the patient's spine," he explained. He said spinal fusion immobilizes part of the spine, which in turn causes stress on the back and its range of motion.

"Also, if you need to fuse multiple vertebrae, recovery time and the chance of complications increase," he added. "With disc replacement, you don't have those problems.

McAfee said the procedure is not right for every patient, but called it "an excellent option" if the clinical indications are followed. He said Charit trial data showed that replacement patients had an 82.5% increase in the flexion and range of motion two years after surgery compared to spinal fusion. He also reported reduced recovery time, in part due to the minimally invasive nature of the procedure compared fusion, with some patients able to undergo the procedure on an outpatient basis. Around 87% of patients who worked were able to return to their jobs within six weeks of surgery.

DePuy, he said, had "taken the high road" with an extensive program of surgeon training. The training program was part of the FDA's conditions for the Charit product approval in June 2004. In addition to disc replacement, the panel identified other emerging treatments for back and spinal problems, including biological disc regeneration and computer-assisted and image-guidance technology such as surgical navigation where a surgeon uses an interoperative computed tomography (CT) scan to assist in the placement of screws and other devices when performing spinal fusion.

"Spinal fusion is still the best option for some patients, bust studies show that in some cases, the screws are not ideally placed," Brown said. "Interoperative CT scans can help with placement of screws when the anatomy is difficult." He said the drawbacks of the procedure are that is technically demanding and very expensive, with some systems costing upward of $500,000. Overall, Brown said this is a situation when "you have to spend money to save money. We do believe we'll get better patient results, and it will reduce the time of complex surgeries."

Companies with technology in this area include Medtronic Sofamor Danek (Memphis), Stryker and a new a start-up, Breakaway Imaging (Littleton, Massachusetts).

Though much of the research into these emerging technologies is preliminary, according to Wang, they show "great promise."

"Back injuries can be debilitating, so it's great to know that there may be even better ways for us to help those patients," he said. "However, we have to ensure that we don't circumvent the research process because everyone's excited about these new treatments."

Also fitting the theme was a presentation on less- and minimally invasive surgery (L/MIS) for total joint replacement. According to panel members, these procedures have become highly requested procedures. Experts in the field discussed the pros and cons of the latest techniques, the need for more accurate measures to measure patient outcome, the best candidates for the procedure, and appropriate training for surgeons.

Current options for total joint replacement include using a six- to 10-inch incision, which cuts muscles to allow surgeons to clearly see and operate on the joint. MIS procedures use only a three- or four-inch incision. Other smaller incisions are required to insert surgical instruments.

"Minimally invasive surgery is a new, comprehensive approach to pain relief and rapid recovery that enables patients to walk independently and return home the same day after surgery, which is truly remarkable," said Richard Berger, MD, orthopedic surgeon at Rush University Medical Center (Chicago), one of the first surgeons to perform minimally invasive total hip and knee arthroplasty as outpatient procedures.

Alfred Tria Jr., MD, clinical professor of orthopedic surgery at St. Peter's University Hospital, Robert Wood Johnson Medical School (New Brunswick, New Jersey), said MIS is a better choice for knee surgery because it allows surgeons to spare cutting into quadriceps muscle.

Tria was involved in the design of a quadriceps-sparing technique for the knee, with which he says patients recover three times faster, have about a third less pain, 30% less blood loss, and 10 degrees more motion of the knee at the end of first and second years after surgery compared to standard procedures.

Pre-emptive analgesia and other anesthetic improvements, improved radiographic imaging, interoperative rehabilitation and patient education also have acted as major contributors to shorter hospital stays and reduction in recovery time, according to Thomas Thornhill, MD, chairman of the department of orthopedic surgery at Brigham and Women's Hospital (Boston).

"Surgeons will move toward using L/MIS techniques based on evidenced-based date published in peer-reviewed journals, not because of market demand for such surgeries," he said.

Incision size is not the more important aspect of the surgery, cautioned Thomas Vail, MD, director of adult reconstructive surgery and the Total Joint Replacement Center at Duke University (Durham, North Carolina).

"The procedure is a total package," he said. "You must focus on all aspects to ensure you get the best outcome from a combination of the right implant and tools, minimal tissue trauma, proper pain management, and the possibility of accelerated rehabilitation."

Going "beyond all the hype," any new technique must be critically examined as they relate to patient outcomes, said Anthony DiGioia III, MD, director for the Institute of Computer-Assisted Orthopedic Surgery at the Western Pennsylvania Hospital (Pittsburgh).

"However, the goals are to develop new techniques that will permit more procedures to be done less invasively with improved accuracy and precision, but also safely and effectively," he added.

'Electronic knee' holds promise

The theme connecting the myriad topics being presented at the AAOS meeting seemed to be technological innovation from product development to making procedures such as knee and hip replacement much less invasive. The electronic knee, or E-Knee, is one such technological innovation that its developers hope will revolutionize the design of knee replacement components. While the name conjures up images of a bionic body part that allows its recipient to run faster, farther, etc., E-Knee is a prosthesis that allows researchers to directly measure forces on the knee internally, something which only has been done previously through mathematical modeling.

Calling it "a real boon" for knee replacement, Clifford Colwell Jr., MD, orthopedic surgeon and director of the Shirley Center for Orthopaedic Research and Education (SCORE) at the Scripps Clinic (La Jolla, California), said E-Knee has the potential to help device manufacturers develop a more durable and sophisticated artificial knee joint. Current knee replacement components have a life of 13 to 18 years and are difficult to replace when they wear out.

"Everyone who has a knee replacement from now on will benefit from this," Colwell told a gathering of press as he explained the technology. Colwell, along with a team of researchers and industry professionals worked to create E-Knee, which was created for research purposes and is not commercially available.

The project has been a 14-year process, beginning in 1991 with concept development all the way to final implantation performed by Colwell in February of last year. For the past 12 months, Colwell and his team have been gathering data from the implant patient.

The components of E-Knee resemble traditional knee replacement parts. An additional thin layer in the lower plate of the replacement contains four small transducers that measure strain across the knee, which changes as the patient moves.

Also part of the lower plate is an elongated post that is inserted into the center of the bone. In the E-Knee, the post contains a multi-channel transmitter and antenna that sent all the force measurements to a computer. The entire process is activated by a removable electronic coil that fits outside the leg or on the patient's belt.

Most of the computer technology within the implant is smaller than a postage stamp.

Researchers began the process of data-gathering as soon as a few weeks following surgery and the testing is ongoing. Real-time data on the distribution of forces to the implant and load-carrying capabilities of the bone were measured.

"We now have hard data on how much force is placed when the patient does any number of movements, like walking bicycling, or even swinging a golf club," Colwell said. "In many ways, this technology redefines the methodology of knee replacement research."

In addition to SCORE and Scripps Clinic, the team involved in designing E-Knee included representatives from NK Biotechnical (Minneapolis), the DePuy Spine (Raynham, Massachusetts) division of Johnson & Johnson (New Brunswick, New Jersey) and MicroStrain (Williston, Vermont).

"We now have a means of knowing exactly where stress is being placed on the knee every time the patient engages in any type of physical activity," Colwell explained. "These specific measurements may not only result in better implant design, but could also allow us to measure the effectiveness of postoperative physical therapy, overall rehabilitation, bracing and the use of corrective orthotics."

Colwell told The BBI Newsletter that this technology could be used to design activity-specific artificial knees. "So many of our patients want to get back on the golf course, for example," he said. "This could lead to replacements based on certain types of strain, tension or movement."

Based on the information gathered from the one patient so far, Colwell said it seems that patients may be ready for more strenuous activity much sooner following total knee replacement than previously thought. The patient in the trial run of E-Knee was described as an "active, older" individual. In his early 80s, he already has had a knee and joint replacement, but is active in sports including skiing, golf and tennis.

The next step in the process, Colwell said, will be to implant E-Knees in younger adults, women, and individuals of varying weights and body types, which greatly effect how the artificial knee would perform. He said five or six new subjects would be receiving E-Knee replacements in the near future.

Coldwell said that about 400,000 knee replacements are performed every year in the U.S., and the number of younger, more active knee-replacement patients continues to rise. As these numbers continue to grow, he said, so will the demand for longer-wearing knee implants that can withstand more rigorous post-surgery activity.

New use of imaging tech in fighting arthritis

During a scientific presentation at the meeting, an orthopedic specialist presented research on a new, non-invasive way to diagnose, treat and monitor osteoarthritis, a degenerative joint disease that contributes to the most common type of arthritis. People with joint injuries due to sports, work-related activity or accidents may be at increased risk of developing osteoarthritis.

Hollis Potter, MD, director of research at the Department of Radiology and Imaging at the Hospital for Special Surgery (New York), has developed a new technique for orthopedic surgeons to detect cartilage degeneration earlier and more accurately.

Potter used magnetic resonance imaging (MRI) technology from GE Healthcare (Waukesha, Wisconsin) as what she called a "non-invasive microscope."

"We're really excited about this," Potter told BBI. "For the first time, MR has the potential to act as a surrogate for interventional biopsies."

According to Potter, a radiologist specializing in musculoskeletal MRI since 1990, what's been missing has been objective outcome measurement. She says physicians traditionally monitor a patient's progress by asking how they're doing, how they're feeling or functioning measuring pain and how they perform daily activities.

The race to develop cartilage "is big business for pharmaceutical companies," she said, and "that's where imaging can act as a surrogate for biopsy. What these techniques do is allow for very early detection of arthritis, beyond anything we could see before," she added.

According to Potter, GE's 1.5 Tesla and 3 Tesla systems demonstrate greater detail of cartilage and soft tissue injury, permitting earlier detection of clinically significant lesions. "This research shows MR provides reliable, consistent, accurate and non-invasive visualization of cartilage," she said. "It is a step beyond what the orthoscope doesn't show. These new techniques provide an objective measurement of when good cartilage starts to go bad, without always having to send the patient into surgery."

Potter also said the new techniques have been shown to be the most sensitive clinical imaging test in demonstrating bone loss adjacent to joint replacements. According to AAOS, particle disease is the No. 1 failure of joint replacement surgery. Potter said MRI technology has been effective in detecting early forms of particle disease, which occurs when bits of polyethylene and metal break off from implants, affecting the bone around the implants.

Potter describes it as a case of the body reacting against its implants, which then can become loose. The morbidity is much worse for revision surgery than it is for the primary implant procedure. "What's really exciting about this research is that we are offering the patient non-invasive cartilage imaging," said Potter. "After the patient undergoes surgery to replace cartilage, these new MR techniques can act as a surrogate for second look arthroscopy. In other words, the patient will not have to undergo a second operation for purely diagnostic purposes.

She also said that MRI is better for patients because it uses no ionizing radiation. "It's not an X-ray," she said. "Patients and the public are worried about that."

Even beyond being able to detect disease earlier and monitor its progression non-invasively, Potter said these imaging techniques provide a better understanding of "the true biologic process" because clinical symptoms often don't follow arm in arm with what's happening biologically. "Even if the patient is feeling better, the disease may be progressing," she explained. "We know that from a lot of previous data that has been reported on different disease states that though patients may feel better, their disease may be getting worse. You have to look at all stages of the disease."

CAOS draws interest as 'adjunct'

One of the meeting's panel discussions addressed advances in the field of computer-assisted orthopedic surgery, abbreviated as CAOS. According to the panel members, CAOS offers an adjunct to current joint replacement procedures, allowing for more feedback, instant information and more accurate decision-making and potentially fewer complications for patients.

Richard Berger, MD, assistant professor of orthopedic surgery at Rush Presbyterian-St. Luke's Medical Center (Chicago), said that CAOS enables better accuracy in the positioning of prosthetic components, but he added that its use is still a little "under the radar." He added: "As CAOS technology becomes easier to use and receives greater recognition in terms of how it enhances surgical procedures, it will be more widely adopted by the orthopedic community."

The presenters likened CAOS technology in the orthopedic surgery setting to a global-positioning system. CAOS systems use optical sensors, computers and infrared cameras to help map out joints for replacement and provide a guide to position implants with much more precision.

The technology fits right in with the current trend of minimally invasive techniques. Computed tomography scans proved a complete 3-D view of the joint, helping to reduce the incision size and trauma to surrounding bone and tissue. Cost is one drawback of the technology, however. Systems can cost upward of $250,000.

Right now, according to panel members, because the technology is in its infancy, it actually adds time to the surgical procedure, and the longer surgery takes, the more blood is lost and the greater the risk of infection.

Anthony DiGioia, MD, director of The Western Pennsylvania Hospital (Pittsburgh), is considered one of the pioneers of CAOS technology, beginning work in the field in the early 1990s. He said the time and cost factors will drop as the technology is more widely used. "We are just scratching the surface," he noted. "My predication is that minimally invasive procedures with CAOS will be combined with tissue engineering within about 10 years or less." This will allow surgeons to perform biologic resurfacing of patients' joint using their own bone and cartilage as implants, instead of the medal, ceramic or plastic versions used today, DiGioia said.

Commenting on this strategy, William Hozack, MD, professor of orthopedic surgery at Thomas Jefferson Medical School (Philadelphia), said: "The only negative I see is when a surgeon thinks a computer is going to perform the operation, forgetting that surgery is an art. "The surgeon," he emphasized, "still makes the biggest difference."

Surge of new-product news

The orthopedic sector saw a ramp-up in announcements of new technology and other company-related news at the AAOS meeting. With more than 460 companies exhibiting, that marked a substantial increase from around 420 at the previous year's meeting in San Francisco. Among the technology featured at the meeting, Exactech (Gainesville, Florida) reported the successful initial implantation of its Optecure bone graft extender for spinal fusion. The surgery was performed by Hansen Yuan, MD, professor of orthopedic and neurological surgery and director of spine research at the State University of New York. He reported that Optecure worked well as a bone graft extender for spinal fusion, was easy to use and mixed well with autogenous bone.

Optecure is demineralized bone matrix (DBM) in a synthetic bioabsorbable polymer carrier, the first FDA-cleared medical device that includes human DBM as a component, the company said. Earlier in February, Exactech introduced OpteMx, another biomaterial designed for spinal and general orthopedic applications. It is an engineered composite designed to chemically and structurally mimic cancellous bone, providing a conductive scaffold for bone restoration.

The company estimates that its products give it a share of an estimated market of about $200 million, representing more than 100,000 surgeries a year performed in the U.S. using DBM products. The market for all applications of synthetic biomaterials is estimated to be $75 million. Bill Petty, Exactech CEO, called Optecure an "important step" in his company's strategy to "strengthen its focus on biologic solutions to orthopaedic problems."

Another company making news at this year's ASOS meeting was LDR Spine (Austin, Texas), which reported receiving 510(k) clearance from the FDA for two of its fusion spine products. LDR Spine formally introduced its product line during the meeting. The FDA gave the nod to the company's Easyspine posterior osteosynthesis system and the BF+ complementary synthetic bone substitute, comprised of beta tri-calcium phosphate featuring outstanding biocompatibility characteristics.

LDR Spine was formed earlier this year to serve the U.S. market. A division of French company LDR Medical (Troyes, France), the company said its products have been used successfully in more than 2,200 procedures throughout Europe.

In other company news at AAOS:

dj Orthopedics (San Diego), which specializes in rehabilitation and regeneration products for the non-operative orthopedic and spine markets, highlighted new products for orthopedic rehabilitation and bone growth stimulation. dj Orthopedics introduced its first functional brace designed specifically to help prevent ACL injuries in active females. The DonJoy Female Fource addresses biomechanical factors that have been implicated in the high incidence of anterior cruciate ligament (ACL) tears in females. The device incorporates the company's FourcePoint hinge technology, which has been clinically demonstrated to increase knee flexion angle, an important biomechanical variable for reducing ACL injury potential.

The company also unveiled its new Velocity ankle brace, a low-profile, lightweight ankle brace designed to prevent abnormal ankle inversion, eversion, and rotation while allowing natural, unrestricted dorsi- and plantar-flexion. The combination of soft goods with a rigid, hinged footplate and calf cuff provides unsurpassed levels of control, fit, and support. Three Velocity versions are available.

dj Orthopedics also reported that it was launching a new soft goods accessory for its DonJoy SpinaLogic bone growth stimulator, which is designed to improve patient ease of use and comfort. The SpinaLogic device incorporates a patented bone-healing signal that only requires a 30-minute daily treatment time to improve spinal fusion outcomes, while competitive devices require hours of daily treatment time.

The company also noted that an independent scientific exhibit being presented at the meeting highlighted the effectiveness of osteoarthritis (OA) braces in offloading the medial compartment of the knee in OA patients. The study found that out of five different OA braces, manufactured by five different companies, only two were effective in offloading the knee, including dj Orthopedics' DonJoy OA Adjuster. The company said the other three braces in the study showed greater variability and less than optimal offloading capability.

The research study was led by Richard Komistek, PhD, professor of biomechanical engineering and director of the Center for Musculoskeletal Research at the University of Tennessee (Knoxville, Tennessee). In his research, Komistek placed OA braces on subjects with substantial unicompartmental OA with degenerative joint space narrowing. They were then studied utilizing fluoroscopic surveillance in the frontal plane of the knee while walking on a treadmill with the brace off and then with the brace on. Each brace was evaluated for its effectiveness at creating medial OA offloading during walking gait. The study was performed without any form of input or financial support from the brace companies.

PhDx Systems (Albuquerque, New Mexico), a provider of technology services for medical outcomes, reported the release of version 2 of its Hip and Knee Arthroplasty outcomes data measurement software. The company said Hip and Knee v2 incorporates physician requests for fewer forms, more comprehensive device data, optional radiographic data and a longer follow-up period. It also incorporates more in-depth cost-driver information, providing better assessment of the economic impact of new procedures and products.

PhDx said the Hip and Knee v2 would allow physician practices to develop their own in-house benchmarks and patient registries. It will provide healthcare organizations with comparative product and economic data and it will provide a cost-effective basis for post market studies for device companies. Hip and Knee v2 outcomes include an optional radiographic evaluation and tracking module that shows when X-rays should be scheduled. Practices can upgrade both the Hip and Knee v2 to include PhDx DRPro Ortho, radiographic image transmit, storage and retrieval software, which allows images to be analyzed online along with corresponding clinical data.

Orthopedic surgeons can choose from PhDx's two delivery models. The Internet-based Subscription Service, delivered through an application service provider (ASP) model, gives surgeons the ability to manage their data entry, tracking and reporting through a secure web connection to the PhDx software. PhDx retains responsibility for providing and maintaining the database and IT infrastructure. This ASP model offers cost-effectiveness and simplicity of use, implementation and maintenance for single or multi-center users.

As an alternative, surgeons can elect to use the paper-based PhDx Data Service Center to outsource the collection, tracking and management of their data with reports sent monthly to the surgeon's office. PhDx offers PhDx(R) e-View to its paper users to access all of the standard patient reports.

Industry colossus Zimmer Holdings (Warsaw, Indiana) demonstrated a new procedure for minimally invasive joint replacement that was developed to expand patient benefits and geographic reach beyond currently available techniques. The Zimmer Minimally Invasive Solutions (MIS) Anterolateral Hip Replacement Procedure was developed in conjunction with Heinz Roettinger, MD, of the Orthopaedische Chirurgie Muenchen (Munich, Germany). Roettinger has completed more than 600 of roughly 800 procedures that have been performed worldwide.

Zimmer said it worked with surgeons to develop and refine both the surgical technique, which involves weaving through the patient's muscles instead of cutting down through them, and the specialized instruments that are required to perform the procedure. "I believe surgeons will find this procedure to be less technically demanding than other true MIS procedures, and they will be pleased to find that there are Zimmer instruments available for implant designs preferred by surgeons around the world," said Roettinger. "Since I first began using this approach, I have found that my patients are able to return to activities of daily living without the traditional pain and rehabilitation time seen with other procedures."

"Anterolateral" describes the surgeon's approach to the hip joint, which allows the patient to lie on their side during the surgical procedure. That position is widely used and accepted throughout the global orthopedic community, making the procedure attractive to a large base of orthopedic surgeons worldwide.

Ray Elliott, chairman, president and CEO, said, "This new, single-incision, anterolateral technique is the next step in our drive to make minimally invasive joint replacement surgery accessible to a greater number of surgeons and patients. We believe it will appeal to surgeons around the globe as it addresses an expanded range of surgeon philosophies and preferences."

The anterolateral technique is one of several new expansions of Zimmer's platform technologies. A new primary hip stem featuring Trabecular Metal Technology for biologic fixation will be released in limited quantities in mid-2005, along with instrumentation compatible with all Zimmer MIS hip procedures.

Potential benefits for patients of Zimmer MIS procedures include less tissue trauma, faster and less painful rehabilitation, smaller incisions and less scarring, and shorter hospital stays (one to two days, rather than three to vie days for standard surgery, with some patients able to go home in less than 24 hours).

Zimmer says it will immediately begin to offer training in the new approach at all Zimmer Institute locations worldwide. The Zimmer Institute provides hands-on training for orthopedic surgeons through its hub location at Zimmer's headquarters in Indiana and at other locations in North America, Europe and Asia.

Medtronic Sofamor Danek (Memphis) reported the latest expansion of what it termed its industry leading system of poly-axial screws, hooks and rods and other internal fixation devices used in spinal fusion surgery. CD Horizon Legacy 6.35 is an addition to Medtronic Sofamor Danek's CD Horizon Spinal System, the largest-selling system on the market. The company said this family of fixation devices, which also includes CD Horizon Legacy 3.5, 4.5 and 5.5, provides for immobilization and stabilization of spinal segments as an adjunct to fusion of the thoracic, lumbar and/or sacral spine.

CD Horizon Legacy 6.35, available with stainless steel or titanium screws, hooks and rods in the 6.35 mm size, is designed to better accommodate patients who may be larger in size or have more severe curves or disc degeneration, Medtronic Sofamor Danek said.

The initials "CD" stand for Dr. Yves Cotrel and Prof. Jean Dubousset, who in 1983 invented a system of instrumentation designed to provide for 3-D correction in order to stabilize the spine as an adjunct to spinal fusion. CD Horizon Legacy 6.35 is the fourth generation of the system they pioneered. The system received 510(k) clearance by the FDA in 2004. It is available in all markets served by Medtronic's spinal business worldwide.

The company said 400,000 patients undergo spinal fusion procedures annually to address degenerative disc disease, deformity or injury of the thoracic, lumbar and sacral spine. Spinal fusion helps stabilize two or more vertebrae to deal with the associated pain, discomfort or impairment of motion.

Zimmer and Medtronic Navigation (Louisville, Colorado) said that the first electromagnetic computer-assisted solutions knee replacement procedure was successfully performed at Methodist Hospital (Houston). David Lionberger, MD, an orthopedic surgeon at Methodist, performed three successful navigation-assisted procedures using the Zimmer Minimally Invasive Solutions (MIS) Quad-Sparing Total Knee Replacement Procedure and Medtronic Navigation's StealthStation with the AxiEM electromagnetic computer assisted system.

Zimmer and Medtronic Navigation, which have an exclusive partnership for MIS surgical navigation solutions, developed the system, which involves computer-assisted equipment, software and Zimmer instruments. The companies plan to officially launch the system worldwide in July.

Centerpulse, which Zimmer acquired in 2003, had previously been involved in development of electromagnetics for orthopedic navigation, but the Zimmer/Medtronic collaboration is the first to produce a successful system for widespread commercialization. In January, a 510(k) was cleared, allowing the Zimmer system to be used in conjunction with orthopedic knee procedures.

Electromagnetic tracking systems are an alternative that enables "significantly more minimally invasive surgical techniques than the use of infrared camera technology," Zimmer said. It noted that the term "electromagnetic" refers to the method used to locate and track the implants and instruments relative to patient anatomy.

The technology consists of an electromagnetic field transmitter that generates a local magnetic field around a specific area of anatomy. The localization system, armed with magnetic sensors, is able to identify the position of instrumentation. The system's ability to track the implant and instrument positions is not related to line of sight relative to the emitter. Electromagnetic mini reference trackers are attached to the patient's bones and the surgical instruments, producing a real-time, 3-D video display of the surgical procedure.

Wright Medical Group (Arlington, Tennessee) introduced its Odyssey Minimally Invasive Knee Instruments at the meeting. The knee instrumentation is part of Wright's Odyssey Tissue Preserving Initiative, a minimally invasive surgery program for hip, knee and total joint resurfacing procedures.

The company said that while many orthopedic manufacturers have developed minimally invasive instruments and techniques, it has concentrated on offering a minimally invasive instrument system that does not require surgeons to radically change their current surgical techniques.

The Odyssey Knee Instruments are designed for use with Wright's Advance series of knee products. Included in the line are the Advance Medial Pivot Knee, which allows natural knee motion and a high level of stability when a patient's posterior cruciate ligament is damaged or resected, and the Advance Double-High Knee, which the company said offers both high stability and high flexion without sacrificing the patient's posterior cruciate ligament.

Designed to more closely mimic the kinematics of the natural knee, the Advance family of knee implants has more than seven years of clinical success, according to the company. With the introduction of the Odyssey instrumentation, it said surgeons and patients "can now experience the known benefits of this innovative knee line through a less-invasive surgical approach."

In another product announcement, Wright and BrainLAB (Munich, Germany), an innovator in image-guided medical technology, reported release of BrainLAB's software for Wright's Advance Knee System on the VectorVision surgical navigation platform. The CT-free knee application will allow surgeons to implant the Advance Medial Pivot Cruciate-Sacrificing, Double-High Cruciate-Preserving and Posterior Stabilized knees. By adapting the software to the clinical workflow, this software integration will allow surgeons to use navigation effectively for all relevant steps of the procedure, the companies said. In addition, surgeons can use BrainLAB's VectorVision with Wright's Advance knees in both traditional and minimally invasive approaches to total knee arthroplasty. BrainLAB's VectorVision navigation system helps surgeons optimize total joint replacement surgery through exact positioning of the implant and precise alignment of the leg axis.

SpineVision (Paris) said it has received FDA clearance to market its PediGuard instrument as a Class II device. The company said this is the first FDA-cleared device for real-time detection of possible penetration outside the vertebral pedicle, a continuing issue in spine surgery. SpineVision said published rates of intraoperatively "misplaced" pedicle screws range from 10% to 40%. Of that number, 2% to 10% have resulted in pathological consequences such as spinal cord damage, including paraplegia or quadriplegia.

The company describes PediGuard as the first wireless, hand-held instrument capable of accurately detecting changes in tissue type, thus alerting surgeons to potential pedicular or vertebral breaches during pedicle screw site preparation. PediGuard is a drilling instrument that constantly monitors the electrical conductivity of the tissue at its tip throughout the drilling process. It measures and translates the electrical conductivity into an audio and visual feedback. Its sensitivity allows the surgeon to know whether the tip is in contact with cortical bone, cancellous bone, soft tissues or blood. The surgeon is immediately informed through variations of sound cadence, sound pitch and LED flashes, when and if the electrical conductivity at the distal part of the instrument changes.

Orthovita (Malvern, Pennsylvania), a developer of orthopedic biomaterials, reported that a poster titled "A Prospective Multi-Center Pilot IDE Study on the use of Cortoss in Vertebroplasty-Report on the First 20 Cases" was exhibited at the meeting. Hyun Bae, MD, of the Spine Institute at Saint John's Health Center (Santa Monica, California), led the study. Other investigators included Philip Maurer, MD, of the University of Pennsylvania Hospital (Philadelphia), as well as Erik Westerlund, MD, Timothy Peppers, MD, and Raymond Linovitz, MD, of CORE Orthopedic Medical Center (Encinitas, California).

The pilot investigational device exemption (IDE) study was intended to provide preliminary information about the use of Cortoss Synthetic Cortical Bone to treat osteoporotic vertebral compression fractures. The study results suggested that a relatively small volume of Cortoss may be able to reinforce the vertebrae and achieve symptomatic relief, as compared to the larger volumes reported in the literature for polymethylmethacrylate (PMMA) bone cement.

Cortoss appeared to have an interdigitated fill pattern, which is intended to create trabecular reinforcement. The study results appear to be consistent with the results obtained in a prospective vertebroplasty study using Cortoss conducted in Europe, Orthovita said.

A larger, prospective, multi-center IDE study is under way in the U.S. designed to demonstrate that Cortoss is safe and effective for the treatment of osteoporotic vertebral compression fractures.

ConMed's (Utica, New York) orthopedic business unit, ConMed Linvatec, a leader in sports medicine technology, launched several new products at the meeting. They included:

  • The Pinn-ACL CrossPin System for ACL reconstruction is the first crosspin device on the market that allows the surgeon to visually confirm femoral graft placement and point of fixation. Pullout strength in excess of 1700 Newtons is a result of the company's proprietary self-reinforced bioabsorbable technology and unique design of the system.
  • The Advantage Turbo Handpiece, the newest addition to ConMed Linvatec's portfolio of arthroscopic shaver products. It features lighter weight, higher speed and increased torque, along with new enhancements such as custom blade positioning, increased aspiration performance and fine-tuned hand controls.
  • The LightWave Suction Ablator, which expands the company's line of arthroscopic ablation products for precise tissue removal. It incorporates a one-piece integrated handle with a 4 mm electrode and center suction for use in arthroscopic knee, shoulder, wrist, elbow and ankle procedures. ConMed Linvatec said surgeons would appreciate the combination of ablation with suction enabling increased visualization during ablation procedures.
  • ThRevo, the first triple-loaded suture anchor on the market, according to the company. Unlike all other shoulder anchors that are either single- or double-loaded with sutures, the ThRevo provides surgeons with three suture placement options, resulting in significantly stronger rotator cuff repairs. The product is pending 510(k) approval.
  • Pre-threaded Herculine now available on many of the company's shoulder anchors for rotator cuff repair is a new high-strength, nonabsorbable high tensile strength suture with what the company termed "superior handling characteristics."
  • The Hall PowerProMax Battery Powered System, a result of the company's continued research and development in powered surgical instruments. ConMed Linvatec said the system offers the most powerful, ergonomic and high-performance battery-powered handpieces on the market. The system is comprised of six specialized handpieces, five for total joint reconstruction and one smaller handpiece for use in small-bone applications.
  • The PowerProMax System also offers the most complete selection of battery solutions available on the market, including several options for battery processing and sterilization. (Tucson, Arizona), an online resource for radiology professionals worldwide, launched its new Orthopedic Imaging Digital Community. This new special section delivers customized, targeted content on musculoskeletal and orthopedic imaging via the web site. The new digital community was launched with daily coverage from the AAOS meeting.

The Orthopedic Imaging Digital Community was made possible through the sponsorship of Orex Computed Radiography (Yokneam, Israel), a provider of compact computed radiography (CR) systems enabling the acquisition of patient X-ray images digitally. Orex is in the process of being acquired by Eastman Kodak (Rochester, New York) in a $50.5 million cash deal announced in January. Hillel Bachrach, president and CEO of Orex, said, "Orex is pleased to partner with to provide this valuable resource for orthopedic healthcare professionals who rely on orthopedic imaging technology to help their patients on a daily basis."