Medical Device & Diagnostic Industry
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An MD&DI August 1999 Column
MDEA AWARD WINNERS
Medical Design Excellence Awards Recognize Form and Function
Twelve companies recognized for outstanding achievements in medical device development received gold awards during the presentation ceremony for the Medical Design Excellence Awards of 1999.
Jeffry Still
This year's Medical Design Excellence Awards again underscore the unique nature of medical device development. Each device recognized for its design excellence was the fulfillment of a vision. Many resulted from the focused efforts of design teams that had been formed specifically to meet a carefully defined technical challenge. Other products were developed by persistent individuals who were struck by sudden inspiration or who looked at conventional technology from a new perspective and saw the potential to make a significant improvement.
It is clear that the need for improved or new medical products continually drives the pursuit of innovation in novel device designs and advanced manufacturing technologies. The emergence of new clinical applications and the availability of new technologies also spark the development of new medical products. These processes, however, are seldom bound by any rigid timetable. Most often, the process is long and arduous, involving years filled with numerous redesigns and prototypes, as well as continuous product and market testing. In rare instances, when all factors are in perfect accord, an innovation will burst quickly onto the market—sometimes within months.
This is the remarkable nature of the process of invention and innovation that leads ultimately to the introduction of new or advanced medical devices. The development of new products clearly requires a knowledge of the general process of technological improvement and an awareness of the many generations of incremental changes that often make predicting a device's ultimate use and design so difficult. Developers must recognize the value of product feedback rendered by users in real-life settings and of the critical role played by entrepreneurs and small companies in the creation of some of the most innovative products. They also must remain aware that the ability to correctly assess future trends and needs is of the utmost importance in the development of products that will succeed in the marketplace.
In developing new devices, designers must also strike a precarious balance between form and function. Does the device perform the tasks necessary to provide the desired medical treatment? Does it offer any advantages over conventional methods? Is use of the product cost-effective? Is the device simple to operate and easy to learn? Will it be readily accepted by end-users?
Form and function, cost-effectiveness, user acceptance, ease of use, and simplicity of training were among the factors considered by this year's panel of eight MDEA judges. The following 1999 gold-award winners were selected for having achieved excellence in their pursuit of innovation and invention.
THE On3: ENABLING HEALTHCARE WORKERS TO MOVE A PATIENT—WITHOUT BECOMING ONE
According to the U.S. Department of Labor, each year 56% of all healthcare workers injure their backs on the job, and back injuries account for up to 80% of total injury costs among this group. Thomas W. Votel, MD, inventor of the On3 lateral transfer device, had witnessed his fair share of back injuries when he decided to design a system that would remedy the situation. "We developed an easy-to-use device that allows one person to do what it used to take six to do. And, better yet, it reduces the risk of a back injury to a respectable level—like zero," the inventor explains.
The On3 allows a single healthcare worker to move a patient by wrapping the patient's draw sheet around the On3's transfer rod, clamping a belt to the rod, and clicking a retract-able, handheld control. The device smoothly transfers the patient from bed to cart in about 20 seconds.
From his initial concept for a one-person transfer device, Votel developed a crude mock-up. Because the common denominator between a hospital bed and a cart is the bed rail, he decided to use a mechanism attached to the bed rail to pull the patient. He took the hand crank off his tennis court net and fashioned it into a 25-lb unit that attached to the bed rail, yet was strong enough to pull a patient when a caregiver simply turned the crank.
At this point, Ergodyne (St. Paul, MN), distributor and manufacturer of the On3, approached redgroup (Minneapolis) to oversee R&D for the device, says the inventor's son, Thomas F. Votel, Ergodyne president and CEO. When the design team took this early, nonfunctional concept to three Minnesota hospitals for validation, the staff members told them they would not want to pick up and carry a device that heavy, and that they had no place to store it. They suggested the design team mount the device on a rolling cart, a commonly accepted way to transport heavy equipment in hospitals.
The R&D program soon changed dramatically, says Lars Runquist, a principal with redgroup. "Real estate is scarce in hospitals. The pushcart idea allowed the device to be moved easily and stored conveniently, even in hallways."
Reliability and strength were other important factors in the On3's design. "We needed a unit that could safely transfer a 500-lb patient, and that would last for years and be reliable to the end-user. If they (healthcare workers) didn't trust the machine, they wouldn't use it on a daily basis," Runquist explains. Extensive life and strength testing of the product were conducted at redgroup to ensure heavy-lifting capability and durability.
"Once we had a workable prototype, we tested it in about half a dozen hospitals," Votel says. In particular, Ergodyne hired the market research firm Marquette Research (Minneapolis) to conduct focus groups at two area hospitals. "We wanted to capture the end-user response to the device before we started the manufacturing process," he says. The focus groups were asked to fill out sophisticated questionnaires and were interviewed extensively for their input.
This research helped designers fine-tune the product's appearance as well as function. "We didn't want a heavy-duty industrial look, like a winch, but one that was simple and accessible, not only for the hospital workers, but also something that looked comforting to the patient," Runquist emphasizes.
"From an interface standpoint, we kept it very simple," Runquist says. "It's battery operated, and the transfer rod folds in half to fit right in the unit for storage. Also, while standing on one side of the bed, the operator can adjust [bed] height with foot pedals, align the patient, and begin transferring by clicking the remote control without walking around the bed several times. Even the remote control has just two buttons, one to adjust for skew [if the patient is off-center] and one to begin transfer."
The name also reflects the device's accessible nature. "We didn't want a name like XJ-2000. The name needed to convey how simple this product is to use," Runquist says. On3 is a reference to a physician's directive to move a patient on the count of three, Runquist explains.
Overall, Runquist thinks the feedback from end-users was the most crucial decision-making tool in the design process. "The users dictated where things should go as opposed to the client," he explains. "We got their input, and every milestone was validated by the hospital staff. The end result exceeded their expectations."
THE ORAL-B CROSSACTION: A NEW ANGLE ON THE TOOTHBRUSH
In April 1996, Brad Baker assembled Team Discovery at Oral-B Laboratories (Belmont, CA). Its mission: to develop a breakthrough product—a toothbrush that could clean teeth more effectively while offering an innovative ergonomic design. After three years of R&D, 26 patent filings, and a $70 million investment in new manufacturing processes, Oral-B has succeeded by delivering the most thoroughly researched product in its history: the CrossAction toothbrush.
One of the first challenges after assembling the design team was to rapidly develop prototypes, Baker explains. "Generally, it takes four to six months from the time we have an idea for a brush to when we can try it out on a consumer," Baker says. "With our dedicated focus on the product (the CrossAction) and a clear objective, we were able to reduce that to five weeks." Ultimately, consumers tested and gave feedback on more than 50 prototypes Team Discovery had designed based on the consumers' input.
Data were obtained from 72 tests involving more than 4000 consumers to determine desirable features, including a head that is tapered to reach back teeth, bristles that can reach around back teeth, high and low bristles to fit tooth shapes and crevices, and a rubber handle for a better grip. Experts then observed brushing and gripping behavior both in laboratory settings and in consumers' homes. Using the data, ergonomists, kinesiologists, and design research experts defined optimal cross sections for the toothbrush bristles, center of gravity location, elastomeric grip zones, and handle-head geometry. The bristles are also microtextured, making the entire bristle—not just the tips—more effective. Blue indicator bristles fade when it's time to replace the brush. Drawing on the expertise of a diversified design team was vital to the product's success, Baker says.
One of the CrossAction's most innovative features is the CrissCross bristle design. High-speed video cameras and computer imaging analysis of people brushing their teeth revealed that bristles are most effective the moment the brush changes direction because that's when they are angled enough to penetrate between teeth. The CrissCross bristles fill the space between the teeth longer than standard vertical bristles. After spending more than $2 million on independent clinical studies, the company determined that the bristle design removes 25% more plaque than today's top-selling toothbrush.
A second notable innovation is the brush's handle design. Research revealed five basic toothbrush grips: precision, power, spoon, oblique, and, the most common, the distal oblique. The CrossAction handle addresses all five grips and various hand sizes by using a unique combination of flat and curved surfaces, and rubber gripping areas.
THE HEMATYPE SEGMENT DEVICE: ENSURING USER SAFETY
Protecting blood samples—and healthcare workers—from contamination, especially in the age of HIV, is a serious problem in blood banks and hospital laboratories where lab technicians routinely draw samples for typing and cross-matching. Typically, a technician obtains a sample by cutting a flexible segment of tubing filled with blood with scissors, then squeezing the sample into a glass test tube. This results in a number of problems, such as blood spraying onto the healthcare worker or work surfaces, sharps injuries from cleaning scissors between cuttings, and the improper cleaning of scissors blades between cuttings, resulting in cross-contamination.
To address this problem, there is the Hematype, a small, disposable plastic device designed to eliminate virtually all problems associated with scissors. The Hematype houses a tiny steel needle that never comes in contact with the healthcare worker's skin. To use the Hematype, a technician places it atop an upright empty test tube in a rack and pushes one end of a blood-filled tube into the device until it is pierced by the needle. The technician then gently squeezes the tube to obtain a blood sample. Because the tubing stays inside the device, once a few drops of blood have been squeezed into the test tube, the remaining sample and Hematype can be discarded in a biohazard medical waste container, reducing a worker's exposure to blood.
"There are other products that improve user safety, but to take it to the next level, we needed to minimize the breaking of the test tube and make a product that is intuitive—one you can understand just by looking at it," says Alan Wanderer, MD, medical director of Medical Safety Products Inc. (MSPI; Englewood, CO).
After a prototype was developed, MSPI conducted a clinical trial with several hospitals and one blood bank. Each facility was given the Hematype and several other devices and asked to compare features and performance. They were not told which product was being tested and were asked to choose the one they believed was the safest and easiest to use. Users' comments confirmed that the Hematype's inventors had created an easy-to-use solution.
To reduce test tube breakage, MSPI designed the Hematype so that its force is vertical and directed at the top, or rim, of the test tube, the strongest part. This design requires less downward vertical force to puncture the tubing segment than do other devices created for this purpose. Most such devices are situated inside the test tube and radial forces can cause the sides of the test tube to break when pressure is applied.
Another challenge in designing the Hematype was in accounting for different blood tubing manufacturers. Each brand of tubing has a slightly different thickness, width, and flexibility, and there are various methods of heat-sealing the segment ends. The Hematype accounts for all types of tubing. The inside of the device is ringed with alternating ribs and slots that are intended to help guide various-sized segments toward the needle.
Getting the healthcare community to accept new safety products can be difficult because of the intense cost-consciousness of most healthcare organizations, a reluctance to change procedures, and regulatory controls that hamper new product development, Wanderer notes. "Because [the Hematype] is disposable, the price was extremely important," he says. "We needed to be able to mass manufacture multimillion units cost-effectively. The mission was to be able to manufacture a product at a low enough cost that permitted acceptable pricing in a price-conscious market. This was accomplished using thoughtful design development both for the product and the multicavity tooling, cost-conscious materials selection, and efficient assembly techniques. The end result has been our ability to market a product at a reasonable price with an acceptable profit margin."
THE HI & DRI ISOLATOR: SIMPLIFYING DENTAL VISITS
The Hi & Dri, a 67-cent plastic oral isolation and protection device, keeps a patient's tongue and cheek out of harm's way while the dentist is at work. The Hi & Dri attaches to a piece of flexible tubing on the dental station's vacuum line, providing the dentist with access to the teeth while simultaneously protecting the patient's tongue and cheek from the drill and keeping the patient's mouth open. The vacuum suction keeps the patient's mouth clean and dry, removing saliva and aerosol mists from the dental drill and particulate material such as stray pieces of filling material. This single device replaces an arsenal of dental helpers including cotton rolls, saliva ejector tubes, tongue depressors, cheek retractors—and, sometimes, even the dental assistant. The device is so effective that it enables a dentist to perform most procedures single-handedly, freeing the dental assistant for other important tasks.
From its inception, the Hi & Dri was on the fast track. DriDent, the developer of the Hi & Dri system, initially approached the industrial designer Microplas Inc. (Clinton, MA) with a breadboard model of the device and with the desire to get molded parts to a dental show in October, which was only five months away.
One of the first issues for the design team to tackle was to determine the appropriate size and form for the device. Although DriDent wanted a shape that would work for 95% of the adult population, two sizes were eventually designed after the company was convinced that a "one size fits all" approach would not work. By using anatomical models and plaster castings of patients' mouths, a series of hand-fabricated models was created. The device shape also had to maximize the working area for the dentist. This meant keeping the material thickness and size of the vacuum chamber to a minimum. After experimenting with several shapes and sizes, a final form was selected and a functional model was created for testing.
"We came up with the concept and designed the best way to manufacture it first," says Steven Callahan, Microplas president. "Then we engineered the device and came up with the final aesthetic form." Pro/Engineer software was used to create the 3-D database that was created during the engineering process. "This would have been impossible with the old 2-D process," says Christopher Reinke, senior product designer at Microplas.
Determining the best and most cost-effective manufacturing process was the most significant factor in the design process, says Callahan. "The downstream people were involved the whole way," he adds. "The collaborative effort between design and manufacturing is the reason for this product's success. Manufacturing an amorphic form required a tricky process—it's not easy to mold." Because of the tight cost restriction, and because the device had to be hollow and airtight to work with the vacuum line, a polypropylene injection molding process was eventually chosen to produce the final two-part design. A secondary ultrasonic welding operation is used to assemble the two halves. Multicavity tooling is being used along with semiautomated assembly equipment to achieve pricing goals and first-year volumes of 4–6 million units.
THE INTUITIVE SYSTEM: MAKING SURGERY EASIER FOR BOTH PHYSICIAN AND PATIENT
Until recently, cardiac patients had to choose between two types of surgery: traditional open surgery and minimally invasive surgery (MIS). Traditional open surgery allows surgeons direct access to the organs but requires a large incision and results in trauma and lengthy recovery times for the patient. MIS minimizes incisions and accelerates recovery time. Such procedures require surgeons to use awkward, long-handled instruments, however, and the surgeon's movements are guided in a counterintuitive way via a CRT monitor. The Intuitive Surgical System eliminates the problem, combining the natural hand movements of open surgery with the less-traumatic benefits of MIS.
A government-funded research project by SRI, a Menlo Park, CA, think tank, served as inspiration for the Intuitive system. SRI's research involved the development of robotic ambulances in which surgery could be performed on wounded soldiers on the battlefield. When the founders of Intuitive Surgical Inc. (Mountain View, CA) came across the project, they realized it held potential for a novel form of MIS and formed a partnership with SRI to use the project as a launching point. Intuitive Surgical made several iterations of the design, resulting in the first product developed by the company, which was a privately held start-up.
Intuitive Surgical also consulted with several local surgeons who used MIS, particularly those with extensive cardiac and endoscopic surgery experience. Based on suggestions from the surgeons, they took the project to the dry-lab stage and worked with animals.
Spearheading a revolutionary product was a daunting task, says Steve Holmes, senior mechanical engineer for Intuitive Surgical. "There was no precedent," he explains. "The details of how it would work mechanically were difficult, and the hardware and software were tricky, but most challenging was envisioning how this would fit into the operating-room environment." The current system is the fifth generation, he estimates. "This [device] has undergone radical revisions as we learned more and more about the surgeon's environment."
The Intuitive system consists of two primary components: the viewing and control console and the remote surgical arm. Surgeons perform procedures seated at a console while viewing a high-resolution 3-D image of the surgical field. Highly specialized visual technology simultaneously transfers the surgeon's exact hand movements to precise microsurgical movements at the operative site, which requires only a 1-cm incision. Pencil-sized instruments incorporating the company's EndoWrist technology function like tiny computer-enhanced mechanical wrists, mimicking the dexterity of a surgeon's hand.
To create an immersive environment akin to open surgery, Intuitive Surgical developed its own proprietary 3-D viewing display system, used advanced robotics, replicated surgical instruments in the console, and created the EndoWrist technology that enhances performance by motion scaling, eliminating hand tremor, and providing sensory feedback. Because the surgeon's movements are counterintuitive in most traditional MIS systems—moving the hand to the left displays as rightward movement on the monitor—the firm addressed the problem by using a more straightforward viewing system.
Ergonomics was another challenge because the designers needed to strike a balance between the working position of a surgeon, who is usually standing up and looking down while operating, and the new position, in which the surgeon sits with arms at a 90° angle and looks at a monitor. Following numerous wood and foam model evaluations and clinical studies, the design team responded by moving some controls, such as camera movement, focus, and cauterizing, to a foot pedal. Hand instruments were modeled after actual instruments but were enlarged slightly, and a comfortable armrest was provided. The stereovision system was improved as well.
Integrating nine subsystems into the design while keeping it simple posed other problems. "We wanted everything to combine to make a surgeon feel that he's working in a minimally invasive environment," Holmes says. "We needed a coherent product that was not intimidating—that surgeons would want to interact with." The design team also needed to keep costs down to make surgery with the Intuitive system competitive with an open-surgery procedure. The entire business model was developed with the goal of not increasing costs for a procedure. Several of the tools are "reposable," meaning they can be used multiple times before disposal, and the cosmetic covers over the console are cast urethane for cost savings. The system "opens up the possibility of doing almost any surgery in a minimally invasive environment," Holmes says.
THE LIGHTSHEER LASER DIODE: COSMETIC HAIR-REMOVAL TAKES A STYLISH TURN
Communicating quality and state-of-the-art technology while instilling trust and confidence in users and patients were the goals behind the LightSheer diode laser system. Unlike other systems that locate the laser source in the console and pipe the light through large and obtrusive tubing, the LightSheer's small, diode laser technology resides in the handpiece. "It's the crown jewel of the system," says Gerard Furbershaw, senior vice president at Lunar Design (Palo Alto, CA), the firm hired by manufacturer Coherent Star Medical Technologies (Pleasanton, CA) to work on the device.
"We wanted to place all the focus on the handpiece and the remarkable technology inside it," Furbershaw says. The handpiece had to be easy to maneuver and trigger, as well as highly ergonomic, correctly balanced, durable, and protected during shipping. "From the beginning we thought the handpiece should be like a pistol. We spent a lot of time with weighted models so we could optimize it for long periods of use without fatiguing the doctor's hand."
With the LightSheer, a dermatologist or medical technician places the power-tool-like handpiece on a patient's skin and depresses a trigger to strike unwanted hair with laser light. Feedback from dermatologists and technicians was invaluable in modifying features and maintaining the device's flexibility and ease of use, Furbershaw adds.
Creating a two-part console was an important design milestone as well. The upper console houses the cpu and handpiece, which account for most of the system's cost. The lower console contains the power supply. The dual-component system enables doctors to keep power consoles at different clinics and transport a single, high-priced upper module between the sites. Servicing the device is also easier because only the relevant piece needs to be shipped.
Meeting Federal Express size and weight requirements was a tough challenge, Furbershaw says. "The outside envelope was already determined (by FedEx)," he says. "It was a constraint for both the top and bottom of the unit and especially difficult to get the console door to hold the handpiece and umbilical cord." For handpiece storage, the designers made more than a dozen models, the first consisting of a coarse foam core. By the end, they were using machined-foam models that would reflect the final elastomeric form. The cord was limited to 6 ft, and the handpiece had to be stored in a recessed area. The final solution kept the interface simple and intuitive and involved wrapping the cord around three times, then rotating and dropping the handpiece into place. To keep the weight below 50 lb, engineers had to minimize the weight of the internal components by using lightweight materials. Because the handpiece is insulated with foam core rather than cast like many devices, it is surprisingly light and not cold to the touch.
The top console contains a tilt-and-swivel touch screen display that folds down during transportation. An elastomeric pocket protects the handpiece when not in use and while being calibrated, and a flexible umbilical cable allows for maximum movement during hair removal. The collaborative relationship between designer and manufacturer resulted in a precise engineering process that took into account material shrinkage rates, strength, warpage, cosmetic finish, and component costs.
THE QUICKIE XTR: MAKING THE WHEELCHAIR "COOL"
Doug Garven's experience as a mountain bike racer was the inspiration for the suspension and shock absorber technology used in the Quickie XTR, a lightweight wheelchair that takes the edge off the harsh impact of daily use.
An industrial designer for Sunrise Medical (Longmont, CO), Garven has also been a wheelchair user for the past 10 years as the result of a car accident. His firsthand experience helped him realize that while many chairs are lightweight and flexible, they are uncomfortable because they offer little protection against curbs, bumps, and other street and sidewalk hazards.
In developing and improving wheelchairs, the trade-off has always been weight versus comfort. Typically, weight receives more emphasis because the lighter the chair, the easier it is to push. Many suspension chairs are not well designed and are simply too heavy. Their rigid tube structure acts as a conduit that transmits shock forces from the road through the wheels and up to the user's spine. "You always try to keep the weight down and the strength up to meet standards, but finding the perfect balance can be difficult," Garven says.
"The suspension is great on mountain bikes, and I wanted to get that into a wheelchair," he says. After finding his inspiration, he developed the first prototype and showed it to the upper-level management at Sunrise. He got the go-ahead and made more prototypes, testing them himself and recording his impressions. By the third-generation prototype, he had tweaked the chair extensively but was still using off-the-shelf shock absorbers by Rock Shox (San Jose), the industry leader in mountain bike shocks. Rock Shox was instrumental in completing the final version of the chair, because it specializes in high-performance, customized shocks for clients like Trek and Schwinn.
The use of custom-tuned shock absorbers like those used in mountain bikes was a key component in obtaining the desired level of energy transfer from the user to the rear wheels. Another important aspect was using a monoshock design, one shock absorber instead of two, which was an industry first. This requires the proper positioning of the shock absorber relative to the user's seating position, but maximizes rear-wheel travel while maintaining energy efficiency. "We played around with where to attach the shock to the swing arm because we wanted a lot of suspension travel but not wasted energy," Garven says.
The dual-shock system used in most chairs has several drawbacks. Obviously two shock absorbers weigh more than one and can create a feeling of instability in leaning to either side. One shock placed under or in front of the user's center of gravity is more efficient and eliminates much of the support tubing, decreasing weight further.
Comfort, usability, and ease of manufacturing were also important to Garven. He designed the chair to be more compact, easier to break down for storage or transport, and easier to maneuver than traditional models. The simple frame design requires less welding and setup, and the use of a single shock absorber makes the wheelchair easier to manufacture. The Quickie XTR also exhibits a quantifiable reduction in vertical impact forces that cause discomfort for the spine and buttocks. As a result, users experience less fatigue and can stay comfortably seated throughout the day.
AIRIS II: IMPROVING PATIENT COMFORT DURING MRI
Magnetic resonance imaging (MRI) procedures have traditionally been uncomfortable. Cramped inside a long, dark tube, a patient feels anxiety and panic, which often leads to incomplete MRI examinations that waste time, money, and resources. To alleviate this problem, Hitachi created the Airis II with an open-gantry design that offers patients a comfortable environment during the MRI examination, alleviating feelings of claustrophobia, and allowing physicians immediate access to their patients for consultation and positioning.
The Airis II design team, consisting of members from Hitachi's engineering and marketing departments, evaluated various configurations to accommodate the most open concept that was technically feasible. In the final evaluation stages, three designs were reviewed with a group of radiologists who use MRI systems before a final design was chosen.
"We were relentless in finding a better open design for a more comfortable patient environment," says Sheldon Schaffer, vice president of marketing at Hitachi Medical Systems America Inc. (Twinsburg, OH). "We placed the structural columns that support the magnet toward the back. This allows access to the patient on both sides, front and back." Although many obese patients often can not be accommodated in the tunnel-like structure of conventional MRI systems, the improved patient table of the Airis II supports up to 500 lb.
Comfort wasn't the only goal for Hitachi. "We didn't compromise on the system's diagnostic quality just for patient comfort," Schaffer says. "We chose components that provided excellent diagnostic quality and took us to a new level of imaging performance." State-of-the-art components include Hitachi's proprietary 0.3-Tesla permanent magnet, a fast and powerful 15-mT/m gradient to provide thin-slice imaging at small fields-of-view for exceptional detail, an advanced digital RF system that provides a high signal-to-noise ratio and extended coverage, and phased-array coils. A 64-bit, RISC-based computer makes viewing and processing fast and efficient, and a Windows-based graphical user interface makes the system easy to learn and use, Schaffer says.
"Even siting the Airis II is easy," Schaffer says. "The magnetic field is very confined, so we can easily place the system into existing facilities. The high-energy permanent magnet material requires virtually no supplemental power; it does not need a refrigeration system to keep it cool, for example." With a space requirement of only 380 sq ft, including self-shielded magnet, user workstation, and all system electronics, and minimal ongoing operating expenses, the system readily fits into existing imaging centers and hospital radiology departments.
BODYFORM: IMPROVING THORACO-LUMBAR FIXATION
Randy Theken, president of Theken Surgical (Barberton, OH), was inspired to develop the BodyForm thoraco-lumbar fixation system after learning from surgeons that they were dissatisfied with existing products on the market. Physicians complained that many of the plates used for temporary spinal stabilization were fracturing, and they needed a plate that would not break. Theken set to work with a surgeon, Ben Taylor, in the United Kingdom to develop a prototype and move to trials within three months. Using Sun workstations, they performed all solid modeling and finite-element analysis and fully developed the product before any sample manufacturing was performed.
The BodyForm fixation system uses a variety of plates, screws, setscrews, and instrument sets. All components are made from implant-grade titanium alloy. Potential applications for the system include anterior decompression and bone grafting, vertebrectomy, and anterior fusion. The system also augments the development of solid fusion.
Although most available fixation systems consist of flat plates connected to the vertebrae with bolts and screws, the new device is designed to fit into the contours of the thoraco-lumbar vertebrae. The heads of the screws have a Morse taper that matches the plates and prevents screws from backing out once tightening force is applied. The body-fitting shape is what most distinguishes the product, Theken says. "It's so easy to put in and fits so well with the spine."
Besides the fracturing problem that initially inspired the device, Theken identified several other areas that needed improvement. Physicians wanted plates that were easier and faster to implant. By eliminating drill guides, temporary fixation screws, and plate-holding forceps, he was able to reduce implantation time. The medial surface contours of the plate fit into the lateral profile of the vertebral bodies, allowing the plate to "guide itself" into the proper spot, and requiring fewer steps and less time to implant. Theken also designed the system so a bone graft would be visible from a postoperative lateral x-ray in order to assess the healing process. The BodyForm system has a large, elliptical window that gives surgeons an additional view to diagnose a patient's progress.
Component fracture and failure was a major concern that is mitigated by enhanced device biomechanics. Because the system provides ledges for the vertebral endplates to rest against, the load is transferred directly from the vertebrae to the plate, rather than to the screws. This direct loading protects the screws from high stress and provides a stiffer construct than other systems that place the load onto the bolts and screws, which are the smallest and weakest components of the system.
Another challenge was the complex geometry of the device, Theken says. "Our system uses improved 3-D geometry that conforms to the body and spine—the other products are two-dimensional rectangles. This required five-axis robotic CNC [computer numerical control] machines." Decreased surgical complexity was also an important goal in designing the system. Other systems have six or fewer plate sizes, which do not accommodate the full range of patient body sizes. Although such systems allow surgeons to keep a small inventory, they also require more surgical skill in using the numerous slots and nests. The BodyForm comes in 11 different sizes with no slots to adjust, no bolts to place and align, and no templates required to start the screws. The surgeon selects the proper plate size, punches a pilot hole with an awl, and drives the four identical screws into place.
INTIMA II CATHETER: ENHANCING AN EXISTING DESIGN
Most disposable medical products present limited design opportunities. Unlike MRI systems, computers, or other high-tech devices that can be enhanced by more aesthetic enclosures and advanced features, an inexpensive disposable device's aesthetic and functional design must be closely tied: function is design, design is function. In the case of the Intima II intravenous (IV) catheter, the design also had to be a surrogate instructor of the product's function because it was being created for use in China, an emerging market.
"We needed a device that could be self-taught," explains Chris Cindrich, industrial designer for Becton Dickinson Infusion Therapy Systems (Sandy, UT). "It had to be obvious to use, because in a country as vast as China, training is difficult." The design team tried to mimic other products that Chinese medical professionals might use, and to incorporate superior technology and materials. The Intima also had to inspire user confidence. "Because of the way it looks, they know how it works. Usually, if we set the product in front of them with a fake arm, they can figure it out," he says.
In most emerging markets, the standard of practice for infusion therapy is a steel needle attached to an extension tube. These needle sets have wings that are used as a grasping element during insertion. All the preliminary designs of the Intima II included such wings, but the final version had only a single wing that can be flipped over for left- or right-handed users. Since this wing is the primary user interface, it includes an intuitive elliptical design and a series of raised touch bumps to indicate where the user should grasp. Because the wing is white, rather than translucent, most users understand that it is acceptable to grasp it, but it should not be left in the body.
User feedback was vital in developing the product, Cindrich says. Field testing was done initially in China, modifications were made back in the United States, and prototypes were again tested in China. Cindrich explains that, "Our biggest challenge was, would they get it? Was it similar enough to existing products that they could use it with confidence?"
Many developing countries still use steel-needle catheters, which are considered poor clinical practice because they can only be left in place for a few minutes, requiring multiple needle sticks each day. With a clinically superior over-the-needle plastic catheter, patients only have to endure one stick every three days. Other benefits are reduced infection and thrombosis rates, mitigated vein damage, less time in the hospital, and less overall discomfort.
Clinicians and hospitals benefit by using a more updated approach with modern technology and by realizing cost savings. One 90-cent Intima II catheter replaces up to nine 15-cent needle sets, requires less labor, and results in fewer complications. It also reduces the overall amount of needle-borne biohazardous waste.
Cost and manufacturing processes were a constraint because the product had to be affordable to developing countries, requiring a streamlined and efficient design. "Everything must come molded into it. You can't apply any extraneous elements when it's being manufactured by the millions," Cindrich says. "You can't afford to add on even one tenth of a cent to it. Every feature must offer multiple benefits to the end-user."
ACCESS CRANIAL PERFORATOR: ADVANCING THE ART OF MODERN NEUROSURGERY
The invention of the Access cranial perforator has all the elements of a classic story: a hero, an innovative scientist in this case, pursues and achieves his goal with fortitude, determination—and a little luck. "Creative work is something you do 24 hours a day," says Eddy Del Rio, inventor of the Access cranial perforator. "An idea can come up at any time, day or night." Del Rio, who is also director of R&D for The Anspach Companies (Palm Beach Gardens, FL), was working on a speed reducer for the pneumatic motors the company specializes in when he accidentally came across information on 24 patents for tools to gain access to the cranium. The discovery helped him realize that little had been done to advance the state of the art in this area.
The main difficulty in gaining cranium access, Del Rio found, was making sure the drill-like tool cut only bone without harming vital brain tissue. Existing tools consisted of concentric blades, one inside the other, that required high pressure to begin cutting, and a clutchlike mechanism a neurosurgeon would engage when reaching soft tissue.
A few weeks later, Del Rio was in his garage refinishing some furniture when inspiration struck. "I had a wood plane in my hand and passed it over the wood and nothing happened. I advanced the blade gradually because I didn't want to cut much wood. I could feel the blade with my finger, and when I went back to the wood, it cut. I realized it all had to do with the angle of the blade and my finger. The blade deflected the flexible skin enough so that it wouldn't cut, but something hard and parallel to it, it would cut," Del Rio recounts. It was suddenly clear to him that the soft tissue of the brain could be protected during surgery by somehow shielding the cutting edge.
Although Del Rio was excited about his idea, when he took the concept to management, they were hardly enthusiastic. They felt the risk and exposure were too great because all the other players in the field were billion-dollar corporations, and an error with this type of product would be catastrophic. He went ahead and developed an initial prototype anyway. When he was done, he invited the CEO into the lab, loaded the device into a power tool, put it against the CEO's palm, and pressed hard. There were no cuts. He had a cranium bone nearby and made a 6-mm-deep, 12-mm-wide cut in seven seconds. Everyone was excited by now, and the project was given the green light.
Of course, there were many problems to solve, such as how to accommodate the diverse topography of the cranium, which varies from 2 to 15 mm thick, and how to safeguard against plunges. The Access cranial perforator uses a pin bridge to prevent dangerous advancement beyond the dura, or soft tissue. The DuraGuard has a smooth, rounded edge and shields the cutting edge unless it is deflected by hard bone and cutting begins. When the perforation of the bone is complete and the DuraGuard meets soft tissue, a pin bridge locks into place while resting on the cranium and prevents further advancement of the perforator. Bone loss is minimized because the Access perforator eliminates bone dust and shards and creates a uniform bone plug that can be used for cranial flap closure. An extended-length center pin stabilizes and centers the perforator to reduce walking or skidding at start-up.
Modifications to the design were necessary because the first prototype had 22 components, making it too complex and costly to produce. Del Rio simplified and unitized some of the parts and eventually whittled down the final device design to only seven parts.
Support for the design came from a local neurosurgeon who was extremely skeptical of the endeavor at first. Devices for drilling cranial burr holes are notorious for being some of the most contentious in modern medicine. Many medical schools will not use them because of the risks involved. When this surgeon tested the device, he selected six of the most difficult parts of the cranium (because of unknown and unpredictable bone thickness) and didn't cut the dura in any of them. "It looks like you have something here," he proclaimed.
Perhaps the best safety endorsement comes from the inventor himself. Says Del Rio: "If my children or myself had to be operated on, I'd feel comfortable with a surgeon using this."
THE UNIJECT: ENSURING SAFE DRUG INJECTION
Developing countries have an urgent need for low-cost, single-dose vaccinations because the common practice of syringe reuse leads to the spread of bloodborne diseases, such as HIV and hepatitis B. The World Health Organization in fact has warned that more than 30% of injections for immunizations are unsafe because of reused needles.
UniJect, a prefillable single-use device for intramuscular and subcutaneous injections, solves this problem in a novel way. The medication is housed in a reservoir, or bubble, and activation occurs when the user pushes the needle shield and forces a double-pointed needle through the isolation barrier. The dose is then delivered by depressing the reservoir with the thumb and forefinger. The collapsed reservoir has a one-way valve that inhibits attempts to refill the device. The device is enclosed in a sealed foil pouch that must be opened at the point of use.
"This is a whole new concept for delivery of injectable drugs that is not based on the standard syringe-and-piston design. The proper use of materials, product design, and high-speed automation equipment enables the production of a low-cost product that can also be processed efficiently at the drug manufacturer," says Roderick Hausser, director of R&D for Becton Dickinson Pharmaceutical Systems (Franklin Lakes, NJ).
After the basic concept and rough prototypes were developed, preliminary design efforts were focused on redesigning the product for ease of manufacture, user safety, and functionality. Prototype molds were constructed for the injection-molded components to produce samples for development on pilot manufacturing lines, product testing, and clinical evaluations. Several iterations occurred, including changing the needle-shield material for improved rigidity and altering dimensions on plastic components to facilitate handling in high-speed automation assembly equipment.
Developing the film-reservoir material was important in determining the final configuration. The material had to be compatible with storing drugs for a long time. The film structure also needed to be easy to form, give sufficient visual clarity for content inspection, seal tightly to ensure closure, protect against handling damage, and ensure structural performance for collapsible nonreuse features. Designing the reservoir shape posed other problems. It had to ensure consistent dose delivery while minimizing drug waste. The reservoir consists of two parts, a straight cylindrical portion and radius domes on each side. During drug release, the two spherical domes are compressed, changing from convex to concave. Once the two concave domes "oil-can in," the reservoir cannot be reformed and reused.
Because the needle is isolated from the drug until the time of injection, the integrity of the medication is ensured until the moment of administration. The prefilled reservoir delivers an accurate dose and requires no calibration or use of syringes and vials. According to the firm, the conventional disposable syringe, ampule, or vial method can be inefficient and can cause vaccine and supply waste because vials and leftover supplies must be discarded after an individual or small-group immunization. Healthcare workers often will deny vaccinations to avoid opening and "wasting" a new multidose vial. With a prepackaged single dose, UniJect reduces vaccine waste and encourages healthcare workers to give individual inoculations. It also produces a lower volume and weight of medical waste compared with glass vials and plastic disposable syringes. This is a significant step forward in improving healthcare in developing nations. "We've developed an injection device that functions drastically differently from a piston syringe yet provides all of the standard and accepted capabilities of a syringe," Becton Dickinson's Hausser says.
Jeffry Still is a freelance contributer to MD&DI. He is based in Santa Monica, CA.
