Biomedical Business & Technology
And BB&Ts

SAN DIEGO — In a time of war, the orthopedic surgeon probably thinks more deeply about the importance of what he or she does, dealing with terrible injuries that can happen to the young, as well as to the old. Injuries are always qualifiers of life but the sacrifices of wartime seem to carry with them more emotion for a profession such as this.

And emotion was apparent in a whole variety of ways and across a broad spectrum at this year’s 74th edition of the annual meeting of the American Academy of Orthopaedic Surgeons (AAOS; Rosemont, Illinois), one of the most venerable of medical association events in the United States.

But the emotion wasn’t uniformly warm and empathetic.

While the membership was engaged in a variety of outreach activities, ranging from volunteer work on a local park preliminary to the conference, to the development of new public relations campaigns focused on the promotion of musculoskeletal health, orthopedics also involves business concerns. Thus, the exhibit area and presentations featured some occasional tension, focused on the need for, and uses of, gender-specific materials for orthopedic therapy.

Technologies that are new and different is a theme of every annual meeting, and so the AAOS gathering also offered a panoply of innovative presentations — ranging from exhibits of the newest, computer-guided systems to panels focusing on the most forward-looking approaches to musculoskeletal treatments.

Emerging: gene therapy emphasis

Orthopedics has long been one of those med-tech areas attracting futurist predictions that natural materials inevitably will supplant metal and plastic. But such predictions have normally focused on the use of biologics and the bioengineering of muscle tissue, tendons and ligaments.

Offering a relatively new spin on this theme in orthopedics is an increasing emphasis on the newest developments in gene therapy — most often seen in the treatment of heart disease, neurological disorders and genetically-based illnesses.

Regis O’Keefe, MD, PhD, professor of orthopedics with the University of Rochester Medical Center (Rochester, New York), billed gene therapy as a “hot topic across all areas of medicine.” Since the high-profile death of young patient Jesse Gelsinger in 1999, which resulted in a halt of gene therapy trials and the resultant flurry of negative media coverage, the field has been steadily — and much more quietly — moving forward.

These developments generally have not been seen very often in the orthopedic sector, but the AAOS meeting made it clear that orthopedic surgeons are becoming increasingly interested in the potential of this strategy for applications targeting arthritis, osteoporosis, orthopedic tumors and tissue repair. In fact, according to Steven Goldstein, PhD, a professor of orthopedic surgery at the University of Michigan Medical School (Ann Arbor), orthopedics may be the field to “get gene therapy out into the public.”

His rationale: that orthopedics would seem to require a more transient delivery of gene therapy, such as stimulation of protein production just long enough to repair a bone, rather than the permanent alterations required in the treatment of other diseases and genetic disorders.

The specific strategies required for delivery is a core issue in gene therapy, with researchers trying the capture the efficacy of viral vectors, as well as the safety and cost-effectiveness of non-viral approaches. Goldstein pointed to studies that have used direct injection of the gene of interest into a wound and emphasized the promise of “direct matrix” delivery, an off-shoot of this approach that involves coating the genes onto a three-dimensional surface which is then implanted into the injury site.

In the case of bone repair, Goldstein told Biomedical Business & Technology, the 3D surface could be a bone graft, a collagen sponge, a metal implant or a bioresorbable implant. The advantage of this approach in healing musculoskeletal injuries is the ability to help bone “come back to life,” O’Keefe said. He pointed to the fact that bone grafts used following the removal of osteosarcomas are “dead” bone, thus not capable of establishing vasculature. And so the micro-fractures that occur due to everyday life worsen until the bone fractures, which can cause failure of the graft and result in amputation.

In a study published in Nature Medicine (11(3): 291-7, 2005), O’Keefe and his team coated a section of murine bone with recombinant viral vectors, encapsulating the genes that encode for RANK ligand and VEGF. When the coated bones were re-implanted into mice, the surrounding bone took up and expressed the proteins, resulting in bone repair. And he said that his group is currently in discussions with the FDA, with the hope of initiating a clinical trial of the technique in the next year or two.

Goldstein said he could see this application of gene therapy being used in combination with — and also potentially as a “next-generation” alternative to — current treatments, such as recombinant bone morphogenetic protein (rhBMP-2). The Infuse Bone Graft product from Medtronic (Minneapolis) contains rhBMP-2 to stimulate bone regeneration. Recombinant proteins, such as rhBMP-2, are limited by their rapid degradation inside the body. Gene therapy could potentially offer the ability to secrete proteins of interest over a much longer period of time.

Goldstein predicted that clinical trials using gene therapy in orthopedic settings will become more common “within five years.” He noted recent advances in other indications, such as cancer, cardiac ischemia, Parkinson’s disease and sickle-cell disease.

With this relative new orthopedic space, Targeted Genetics (Seattle) is conducting a Phase I/II trial of tgAAC94, a tumor necrosis factor-alpha inhibitor delivered via a viral vector to treat inflammatory arthritis. Additionally, Tissue Repair Company (San Diego) has conducted early-stage clinical research in wound healing using a collagen matrix coated with virally-delivered human Platelet-Derived Growth Factor-B (PDGF-B).

Non-profit and government agencies are also increasing their funding for gene therapy research in the orthopedic space.

Fighting the ‘gender-specific’ battle

While orthopedic manufacturers engage in the usual competitive market battles, Zimmer Holdings (Warsaw, Indiana) over the past two years has put major emphasis on a differentiating marketing effort, in the development of “gender-specific” implant products specifically for women and claiming this addresses anatomy that is different from that of men — in so doing, putting its competition somewhat on the defensive.

At last year’s AAOS meeting, Zimmer launched the Gender Solutions Knee, a knee-replacement product designed to account for the differences in male and female anatomy. The company recently reported that nearly 10,000 surgeries implanting the Gender Solutions Knee were performed in 4Q06, which exceeded company expectations by more than 30%. Spokesperson Brad Bishop told Biomedical Business & Technology that the company has 510(k) clearance for a Gender Solutions Hip that will be launched this year.

Adding additional fuel to the marketing fire, Zimmer came to the ‘07 meeting touting a research emphasis, with its presentations at the meeting structured around this evidence-based strategy. And a special Gender Solutions hip research area and a surgeon education presentation on gender issues in the hip was featured at its AAOS exhibit.

Specifically, it was promoting the upcoming introduction of the Gender Solutions Natural-Knee Flex System and surgeon clinical experiences with the Zimmer Gender Solutions Knee that was released last year, it said.

In terms of the hip sector, Ray Elliott, president/CEO and chairman of Zimmer, said in a statement, “Our gender-focused hip research reflects the ongoing efforts at Zimmer to address very real anatomical differences with product designs and corresponding surgical techniques that help surgeons continue to improve clinical results for their patients. We are committed to expanding our leadership in understanding and addressing women’s musculoskeletal health and are working to apply our gender-specific design philosophy wherever it is appropriate across our complete product line. “

A distinction with no difference?

The competitive response has been to push back with the argument that Zimmer is promoting a difference that does not exist.

As a rather large and very overt challenge to Zimmer’s approach, Exactech (Gainesville, Florida) at its exhibit put on display a two-story banner — positioned directly across from the massive Zimmer booth — asking the question, “What Gender Issue?” as a challenge to Zimmer’s gender-specific emphasis

“We took into account the differences between men and women when we designed our Optetrak knee 30 years ago,” Priscilla Bennett, director of marketing communications and public relations for Exactech, told BB&T. And in its brochure on its Optetrak product, the company took an additional slap at Zimmer, saying that “one manufacturer found that the shape of its implant did not successfully meet the needs of many women, so they created a new gender-specific implant for women to correct this design deficiency.” The brochure goes on to discuss a lack of clinical data supporting the gender-specific knee, saying it “may fail to meet the needs of a majority of female patients.”

The sentiment at the booth of Smith & Nephew (S&N; Memphis, Tennessee) was similar. “Zimmer did a poor job of sizing [its knee] to begin with,” Stefan Kreuzer, an engineer on the Journey Deuce knee, told BB&T.

Chris Robinson, a senior product manager in knee systems for S&N, said that size, not gender, is the key issue in terms of implant fit. “Our sizes are non-linear; a size 2 is not a scaled-down version of a size 8,” he said. “The smaller sizes are more applicable to women, and the larger sizes are more applicable to men.”

The differences between men and women were further discussed by a group of orthopedic surgeons during a media briefing. The presenters concluded that men and women do differ in almost every organ system studied, most obviously in how women metabolize medication and perceive pain, but also in terms of different rates of stress factures, osteoarthritis and non-contact ACL injuries.

Regarding the Gender Solutions Knee, pediatric orthopedic surgeon Laura Tosi, MD, of Children’s National Medical Center (Washington), said there is “still not a lot of data” on differences and outcomes, though she granted that the subject “will be very interesting to watch.”

Gender differences may be just the beginning of this debate in orthopedics. Zimmer’s Bishop said that the company intends to “continue to explore” differences in ethnicity. And it already has launched a high-flexibility knee designed for Asian markets, where squatting and kneeling are more prominent cultural behaviors. Bishop noted that the product has “caught on in Western markets as well.”

Hip resurfacing coming on

A relatively new technique to repair hips — known as hip resurfacing — got a cautious reception at the annual meeting, with many still skeptical that the technology is ready for widespread use.

S&N is the only manufacturer with FDA approval of this technique. Its Birmingham implant replaces the hip joint with a metal ball and cup. Surgeons cut away a tiny amount of the top of femur, conserving bone, vs. a more invasive total hip replacement.

The field is likely to get more crowded soon as Corin Group (Cirencester, UK) in late February received an FDA orthopedic advisory panel recommendation to approve its Cormet device for this purpose. Significantly, perhaps, the approval came despite the lack of a control group in the company’s clinical trial. If approved, the Cormet will be marketed by Corin’s U.S. partner Stryker (Kalamazoo, Michigan).

Other companies hoping to win U.S. approval for hip resurfacing include Wright Medical Group (Arlington, Tennessee) with its Conserve Plus device, and executives of Wright spoke in support of approval for the Cormet at the ortho advisory panel meeting.

Thomas Schmalzried of the Joint Replacement Institute (Los Angeles) said the technology may be superior for a select sub-group of patients. He said a newer version of the technique, with metal on metal bearings, may be a better fit for some patients, including those that are younger and have strong bones.

Schmalzried, who is involved in developing Wright’s product, noted that 10 years of clinical experience in research settings outside the U.S. show the procedure has merit. But he noted that women and patients over the age of 65 are at substantially greater risk with the procedure.

TKR and great alignment

One of the technologies promoted at the AAOS meeting as effective, without qualification, was image-guided technology for providing knee implant alignment with near pinpoint accuracy. For patients undergoing total knee arthroplasty, close to perfect alignment should translate into longer durability of joint replacements, according to a panel of orthopedic surgeons who discussed advancements in computer-assisted total knee replacement (TKR) surgery.

Roughly 300,000 knee replacement surgeries are performed each year in the U.S. Standard knee replacements require the use of an intramedullary (IM) rod, inserted up the length of the femur to determine proper knee implant alignment. No IM rod is necessary for the computer-assisted approach, reducing the risk of fat embolization, a complication that can cause acute respiratory distress. The quality and accuracy of the image guidance may enable surgeons to use smaller incisions while achieving the same successful outcomes.

“Computer-assisted total knee arthroplasty surgery is making rapid progress,” said Daniel Berry, MD, professor and chairman of Orthopedics at the Mayo Clinic (Rochester, Minnesota). “Contemporary methods of computer-assisted surgery now have been proven to provide a high level of accuracy in experienced hands. Current efforts are focused on making the process simpler, more efficient, and more cost effective. As these methods evolve, it seems likely some form of computer assistance will eventually become a routine part of total knee arthroplasty.”

Computer-assisted TKR involves extra time and additional difficulty because it still is in its infancy. As the power of the technology and techniques become more established, it will become a more common procedure and an option for more surgeons and patients, according to AAOS.

Emphasis on war injuries

With considerably less debate, one topic appeared frequently at center stage of the conference: the treatment of war injuries. A panel of orthopedic surgeons, versed in the horrific battle wounds seen in Iraq and Afghanistan, discussed new ways of forging treatment plans for military personnel who in previous wars would have died rapidly from their injuries.

According to the U.S. Department of Defense, the likelihood of surviving a battle wound during World War II was 69.7%. That number has increased to 90.4% in the Iraq war. This is predominantly because of “body armor, battle field hemorrhage control and rapid evacuation,” said Michael Mazurek, MD, of the U.S. Navy.

This is of special significance to the orthopedic sector, however, because while the use of body army has served to protect soldiers from many types of upper-body wounds, such armor leaves the arms and legs vulnerable. Nearly 24,000 soldiers have been injured, thousands of whom have sustained wounds including limb amputations. About 47% of the wounds among Marines in Iraq between March 2004 and February 2005 were fragment and/or blast wounds. An estimated 25% of injuries were gun shot wounds and 21% were blunt trauma.

Four orthopedic surgeons addressed the unique character of these injuries at the meeting, and Captain D.C. Covey, MD, U.S. Navy chair of the Department of Orthopaedic Surgery at Naval Medical Center (San Diego), noted that about 70% of the new war-wounded have injuries affecting the musculoskeletal system.

“We see unique war wounds predominantly due to high energy exploding ordnance such as mortars, RPGs [rocket propelled grenades] and IEDs [improvised explosive devises], that are uncommonly seen in the civilian practice,” Covey said. “Infections that may evolve from the repair of large soft tissue and bony defects challenge us as we treat, transport and continue more sophisticated care away from the battlefield. The fact that our military surgeons often first operate on patients very near the battlefield, and then transport them by air to progressive levels of care across continents, presents unique challenges.”

Explosive injuries and military gunshot wounds are often associated with severe bony and soft tissue injury and can frequently involve the upper extremities. Debridement of injuries often occurs shortly after wounding, with serial debridements often needed for complex or severely contaminated injuries.

The panel members addressed infection, wound exploration, and how to treat severe fractures and improve amputee care. Protocols showing success include surgical debridement, leaving wounds open, early fracture stabilization, broad-spectrum antibiotics and rapid evacuation to tertiary care facilities in the U.S. via Germany.

The current system for battlefield medical treatment involves units known as Forward Resuscitative Surgery Systems (FRSS). Each FRSS is made up of an anesthesiologist, general surgeon, orthopedic surgeon, critical care nurse, advanced emergency medical technician, field medical technician and two operating room technicians. The primary goal of the team is rapid treatment — hopefully within an hour — but not necessarily to fix everything in the field. Team members perform either definitive surgery or “damage control,” depending on injury extent.

Captain HR Bohman of the Camp Pendleton Naval Hospital (Camp Pendleton, California), said that definitive surgery — performed for less serious injuries including penetrating wounds to the abdomen or chest — offers the advantage of only requiring a single procedure for the patient.

Controlling damage

But “guys who come in with severe injuries get damage control,” he told BB&T, which includes stopping the bleeding, controlling contamination and restoring perfusion, and then evacuation to a facility where injuries can be fully treated.

To stop severe bleeding, Bohman said the team often packs the wound with bandages. Developing products for hemorrhage control is an area of interest to healthcare companies, and just last month Nanopeutics (Liberic, Czech Republic) signed a technology and product development deal with HemCon Medical Technologies (Portland, Oregon), focused on hemorrhage control in military markets.

Controlling contamination in the field is a necessary step in reducing infections. While in the past, antibiotics were used primarily to treat follow-on infection, studies indicate that antibiotic use at the time of injury, in a prophylactic rather than reactive fashion, can reduce infection rates two-thirds to three-quarters.

An example is the implantation of antibiotic beads, or surgical cement balls impregnated with antibiotics, into an area of bone where fragments have been blown away to prevent infection.

When it comes to restoring reperfusion, FRSS units use vascular shunts to “keep the guy alive and keep the limb alive” until a larger medical facility can complete vascular grafting, Bohman said.

And last month Vascutek (Renfrew, Scotland) reported FDA 510(k) clearance of its Temporary Limb Salvage Shunt (TLSS), designed specifically for vascular use to salvage limbs injured by trauma (see sidebar, next page).

The surgeons agreed that additional research is needed to further advance orthopedic care for the severely injured, focusing on maximizing functional recovery in order to improve their chances of leading a full life. Much of their work has involved delineating what topics should receive priority in government research funding to help those wounded now, and to contribute to orthopedic improvements in the future for others who suffer grievous injuries.

From benchtop to bedside

One of the global issues tackled at the meeting was the movement — or translation — of scientific research into clinical development.

During a panel titled “Benchtop to Bedside: Examining the Barriers Between the Research Laboratory and the Clinical Setting,” an audience poll revealed that 52% of attendees feel scientists do only “marginally well” at using information from basic science in their pursuits of applied therapies. (Other results from the poll are presented in the Table, below).

Referring to the early-stage work in gene therapy and stem cells presented at the conference to treat osteoarthritis and other conditions, Joshua Jacobs, MD, professor of orthopedic surgery atRush University Medical Center(Chicago), said these biologic techniques have “a long way to go” before being widely used in patient care. He pointed to a lack of “high-level clinical research studies showing new approaches are better than existing joint replacement technology.”

Translating basic research into real improvements in patient care is critical in all areas of medicine, but particularly in orthopedics, where the total cost of treating musculoskeletal injuries tops $149.4 billion annually, according to AAOS. The panelists cited the rigors of regulatory approval as a primary hurdle that translational medicine must negotiate.

Even though there are an estimated 15,000 medical device manufacturers in the U.S., Jacobs complained that he sees “the same materials used over and over.” The panel attributed this to the large time- and cost-savings of the 510(k) pathway rather than the premarket application/approval pathway.

Another hurdle underlined by the panel is the lack of funding for translational research. Venture capitalists have increasingly shied away from early-stage research in favor of funding opportunities that provide a nearer-term exit. And they cited the fact that physicians have very little time available to interact with basic researchers. Yet collaboration between the two is key, as physicians can provide practical input as to whether or not a good research idea can be realistically applied.

Jacobs mentioned a new NIH grant mechanism known as the Clinical and Translational Science Awards (CTSA). He reported that the first round of applications were received in 2006, and most requested funding to develop centers for translational research. He also cited an award known as F32, part of the Ruth Kirschstein National Research Service Award Program, that goes to individual postdoctoral fellows and has been used to give orthopedic residents in training hands-on experience in how to conduct clinical trials.

New product offerings

Besides these presentations giving broad views of the field and its challenges, a variety of new products were rolled out at the meeting.

Medtronic (Minneapolis) reported the availability of the Synergy Experience StealthStation System, combining, it said, navigational procedural solutions with minimal access spinal technologies to better treat spinal conditions by enabling less invasive procedures, smaller incisions and less exposure to radiation.

The Synergy system is designed to enable surgeons and their staff to shorten operating room set-up and procedure time by using software that stores surgeon preferences for each procedure. The system monitor also provides glare-free clarity and the wireless surgeon mouse is fully functional on a variety of different surfaces, allowing for more control and maneuverability in the sterile field.

“Image guidance allows visualization of the spine in multiple planes, simultaneously, like having multiple c-arms activated continuously throughout the procedure,” said Choll Kim, MD, an orthopedic surgeon at the University of California (San Diego). “This provides me with a better 3-D view of the spine and has allowed me to perform complex minimally invasive surgeries in a safe and reproducible fashion, without the burden of wearing uncomfortable lead equipment and the intrusion of the c-arm into the surgical field.”

Canon Medical Systems, a division of Canon U.S.A (both Lake Success, New York), demonstrated how its digital radiography (DR) systems help to streamline and improve a physician’s image workflow. Tsuneo Imai, director and general manager, Medical Systems Division, Canon U.S.A., said, “Today, Canon offers portable DR solutions that deliver excellent image quality, virtually seamless network and workflow integration with DICOM Standard-compliant devices to the orthopedic community.”

Canon DR systems and solutions exhibited at the meeting included Portable DR Systems and Canon DR Image Viewing Software.

• Besides its emphasis on gender-specific products, Zimmer featured its Computer Assisted Solutions (CAS) product portfolio, including expanded applications for its Brigit Bone Resection Instrument Guide and for the iNAV Portable Electromagnetic Navigation System. The company also introduced its disposable Zimmer ICE Cube Instruments for increased precision and ease-of-use in surgery.

“At Zimmer, CAS technologies are not machines intended to replace surgeons; they are value-added SmartTools designed to assist surgeons in improving their clinical results,” said Ray Elliott, Zimmer chairman, president/CEO.

Brigit is intended to provide the surgeon with the ability to accurately position instruments based upon patient-specific, pre-operative plans established through a software interface. The surgeon then makes surgical cuts at precise angles required for the patient’s specific anatomy while the positioning arm assists the surgeon in maintaining the desired position.

Based upon internal estimates only, the device may potentially have a payback of less than one year in hospitals doing 1,000 total knee procedures or more per year. Reduced surgery time may create productivity gains of up to 100 more cases a year, the company said.

Conmed (Utica, New York) reported that its Conmed Linvatec business unit introduced the IM4000 TrueHD high definition camera system, the 24K irrigation system, and a new hip arthroscopy Kit. The IM4000 is designed for use in many types of endoscopic surgery including arthroscopy, laparoscopy, urology and OB/GYN.

The company said the camera system gives surgeons an increased horizontal field of view with a wider screen image to provide a much fuller visualization of the surgical site. With the greater number of pixels, the company said this system has significantly increased resolution and three dimensional perception that offers surgeons greater image quality to a level previously unattainable.

The 24K irrigation system is the company’s newest high-end fluid management system that provides fluid to the joint space for irrigation, distention and hemostasis during arthroscopic procedures. This system includes an inflow/outflow/suction tube set, a shaver sensor, an interarticular pressure sensor, and a remote control.

The new hip arthroscopy kit includes two 120 mm disposable operative cannulas, a 17 g hip distention needle, 40 cc syringe, guidewires, switching stick, extended length banana knife and skin marker/ruler.

Orthocrat (Tel Aviv, Israel) showcased its TraumaCad surgical planning, integrated with the Synapse PACS system from Fujifilm Medical Systems USA, the two companies joining forces last year. A digital orthopedic surgical planning and templating solution, TraumaCad enables manipulation of soft-copy medical images, incorporating visualization of fixation and prosthetic systems. Fujifilm’s drag-and-drop interface enables seamless comprehensive workflow.

The integrated Orthocrat/Fujifilm solution is accessed through a single point of entry, with Synapse providing authentication for both systems. Once logged in, physicians access patient images through the PACS and drag and drop them into the TraumaCad workspace.

TraumaCad enables comprehensive digital planning of a full range of orthopedic surgeries, provides a library of prosthetic templates, and includes an advanced modular deformity correction and pediatric package. Completed surgical plans are saved to the Synapse archive along with other patient files and may be displayed in the operating room. Based on thin-client, Web-based architecture, the Orthocrat-Fujifilm solution supports secure Internet access to the complete digital orthopedic work environment.

“Within the past year, we have installed the Orthocrat-Fujifilm solution for more than 20 enterprise customers,” said Bill Urban, Fujifilm’s Synapse product manager. “Healthcare facilities recognize the power of combining a highly flexible and scalable PACS with a leading digital orthopedic surgical planning tool to deliver an advanced solution for their orthopedic departments.”

Clinical studies unveiled

A variety of clinical studies were reported at the meeting.

• Researchers prsented data from the Osteoarthritis-(OA) trial using Orthokine, a product from Orthogen AG (Dusseldorf, Germany). The prospective, randomized, double-blinded, placebo-controlled multi-center trial at Heinrich-Heine-University Dusseldorf (Dusseldorf, Germany) included 380 patients.

“Patients treated with intraarticular injections of Orthokine showed significantly better clinical improvement during the 26 weeks observation period compared to patients injected with hyaluronic acid (HA) or saline”, said the principal investigator, Axel Baltzer, MD, Center for Molecular Orthopaedics. Orthokine-treatment produced a significant reduction in pain-scores as well as improvement in health-related quality of life after seven, 13 and 26 weeks.

Orthokine is a medical device to produce an autologous conditioned serum (ACS) which contains anti-inflammatory cytokines such as IL-1Ra and growth factors.

“The trial shows that Orthokine is safe and effective not only for the treatment of sciatica but also against OA,” Baltzer said.

“The problem with conventional OA-therapies such as analgesics, steroids and hyaluronic acid is that they act on the symptoms but for the most part leave the underlying causes of the disease untouched,” said Peter Wehling, MD, inventor of the Orthokine-treatment an expert in the role of cytokines in pain and inflammation. In contrast to standard treatments, Orthokine acts on the underlying mechanism of arthritis and prevents further cartilage degeneration in joints.

Chronic musculoskeletal pain conditions such as osteoarthritis and degenerative spine disease affect 10% to 20% of the population.

The Center for Molecular Orthopaedics specializes in the biological treatment of joint and spine diseases.

• According to a study done by the Mayo Clinic, minimally invasive surgery (MIS) in the orthopedics sector is not complication-free. This type of surgery takes more time than the conventional surgery and more anesthesia. It also can cause more muscle damage than the traditional “open” surgery. Other studies have shown “sub-optimal positioning of the knee implants” and virtually no difference in recovery time.

John Callaghan, MD, professor of the Departments of Orthopaedic Surgery and Biomedical Engineering at the University of Iowa College of Medicine (Iowa City) and spokesperson for the AAOS, expressed concern about the number of surgical “revisions” resulting from problems related to the first surgery. Callaghan was joined by Steven Woolson, MD, Lawrence Dorr, MD, and Thomas Sculco, MD, for a media briefing entitled, “Hot Topics in Hip Replacement.”

There are several reasons for the high number of revisions, the said, including restriction of the visual field. “When doing MIS, the surgeon is working with inserting devices through a very small incision. It is critical that [surgeons] make sure the components are in the right position,” Callaghan said.

Another complicating factor is patient size. Obesity is a growing problem in the U.S. Obese patients are not good candidates for hip replacement surgery. “It is very important that we have the good surgical candidates with correct fixation of the parts in hip replacement surgery. I do not want to see this procedure go ‘backwards’,” Callaghan said. In the final analysis, orthopedic surgeons consider long-term durability of the hip replacement more important than the length of hospital stay.

• In its exhibit booth, PLUS Orthopedics (San Diego) bannered the results of a prospective, randomized study concerning its PiGalileo computer-assisted surgery system as compared to conventional total knee replacement, published in the February issue of The Journal of Bone and Joint Surgery. The study reported that 25% of the conventional knee replacement procedures fell outside of accepted tolerance range of 3 degrees, compared to about 3% with the PiGalileo system.

Conducted by Dr. Georg Matziolis and colleagues at the Center for Musculoskeletal Surgery, Charit -University Medicine (Berlin), the study included 60 patients with arthritis of the knee who were undergoing total knee arthroplasty. The patients were randomly assigned to one of two treatment groups: the group to undergo surgery with use of the PiGalileo system (32 knees), and the group to undergo the conventional procedure (28 knees). The post-operative spatial position and alignment of the knee implants was evaluated with computerized tomography.

Surgeries done with PiGalileo are performed by a surgeon, with cut guides that can be precisely adjusted with 6 degrees of freedom. By rigidly holding the femoral cut guide, the system eliminates the need for pins which are a significant source of alignment deviation and provides intra-operative feedback to improve precision and ligament balance, for better balance, implant alignment, and positioning.

Plus Orthopedics USA — a subsidiary of Plus Orthopedics Holding AG (Rotkreuz, Switzerland) — reports that the PiGalileo System has been used for more than 15,000 joint replacement procedures internationally since 1999.