Technical Results:research.vuse.vanderbilt.edu/srdesign/2006/group11/Fi… · Web viewEurope has the second largest regional market, accounting for 34.1% of the global market’s

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Abstract

VEXTEC Corporation is a product reliability consulting firm based in Nashville. They have developed a risk-based approach for design and fleet management using a new software tool called Reliability Chain Management (RCM). The company has researched a unique approach to predict the reliability and fatigue failure rates for various complicated devices, and has proven its capabilities in the aerospace and automobile industry. Rather than being empirically-based, the methodology is a physics of failure-based software that incorporates algorithms for crack nucleation, short crack growth and long crack growth. VPS-VIEWz can assess the reliability of systems, and identify weak sub-systems. VPS-MICRO performs detailed analysis on the components that have low reliability. To assess feasibility of VEXTEC’s tools in the medical device sector, Endolite ESKMKL knee prosthesis was analysed for reliability using a top down approach. Stresses were simulated for a 220 lb jogging man. The strut assembly was analysed for failure in bolt, trunnion and the Pneumatic Swing Phase Control and predicted number of failures were calculated for each. The finite element analysis was performed on the strut components and VPS MICROTM software was use to predict the long term reliability for the strut assembly components. A marketing plan to launch VEXTEC in the medical device industry was formulated. The medical device and prosthetic markets are analyzed. The FDA and other regulatory considerations for medical devices are analyzed to create a value proposition for VEXTEC’s techniques. Benefits that a medical device manufacturer can expect from using VEXTEC’s are reduced cost and time in physical testing, structure warranties, better reliability and fewer recalls/liabilities. A competitor analysis showed that Ridgetop would be a direct competitor, while companies with statistical reliability methodology like Relex and Reliasoft could be used as substitutes by the industry. Marketing strategy revealed that Otto Bock, a leading prosthesis manufacturer should be considered as the first target to extend VEXTEC into the medical device industry.

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Introduction

The Age of Technology is marked by a demanding consumer market that chronically warrants faster, bigger, better, and functionally enhanced machinery. At the same time, the increasing dependency on complex devices from cars to computers deepens the ramifications of latent failure in designs. The heightened liability associated with injury as well as inconvenience, dissatisfaction and pollution of brand-name necessitate prescience to product reliability.

The statistical quantification of product reliability is typically delegated to small specialty units buried deep within large corporations. However, the corporate management alone also typically retains responsibility for locking in a sustainable market brand, product sales, and corporate revenue. Therefore, the product reliability methods within specialty groups are of supreme importance in shaping the high-tech industry, from the platform of corporate operations to the demands of the consumer market.

In the past decade, there has been a centralization of capital allocation and international research efforts within the healthcare technology pipe-line. While the forces driving innovation are powerful, restrictive Food and Drug Administration guidelines serve as the gatekeeper to the development and delivery of robust consumer products. Because medical technology may affect virtually all aspects of quality of life for the patient, the healthcare market is hypersensitive to the superior product. Mere subtleties in performance and design of the superior product may make an entire niche market obsolete. Because considerable capital investments are at stake and market success is often determined by small differences in evolving technologies, an effective reliability testing method is essential.

Product reliability methods are relatively uniform across industries comprising complex engineered systems. Methods include probabilistic analyses of component failure, supplemented by physical testing. VEXTEC Corporation has developed a methodology physics of failure models with innovative probabilistic methods to predict component failure in fatigue. In addition to component failure, system level reliability can be computed using the reliability of the sub-systems through VPS-VIEWzTM. Thse tools are computationally efficient and can be run on a 1.8 GHz Pentium desktop computer. The enabling technology incorporates Reliability Chain Management (RCM), an enterprise level decision-making process and a comprehensive business intelligence approach. Since the Federal government provided a $10 million grant in 2000, the platform technology has been validated by predicted failure within a 95% confidence interval and documented cost savings.

VEXTEC Corporation is a technology company based in Nashville, Tennessee founded in 2000. While VEXTEC currently operates on a client base within the aerospace and automotive industries, the goal is to leverage the proven record of success and diversify their client portfolio within the healthcare industry. However, the transferability of the VEXTEC platform prompts proof of concept and validation of reliability analysis methods in medical devices. Furthermore, the target market surrounding a specified medical device dictates the market potential of the VEXTEC technology. Once a specific prototype is selected, the designation of design parameters structure the failure mechanism algorithm. The integrity of the reliability analysis platform is dependent on precise criteria and parameter specifications such as material selection and component geometry, based on the test device. Therefore, the project goals

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are: (1) Apply VEXTEC’s tools to a medical device to assess reliability. (2) Perform finite element analysis on a prosthetic sub-component (3) Use the VEXTEC physics of failure models to predict the minimum time to failure and the sites of failure of the sub-component (4) Analyze the medical device market and quantify a value proposition and a marketing strategy for VEXTEC

Feasibility analysis of the prescribed VEXTEC method encompassed fatigue failure associated with loading in a transfemoral prosthetic device. The preliminary prosthetic device for technology feasibility analysis was proposed based on simplicity of design, and lack of biocompatibility complications. Within the broader prosthetic market, the advent of modular prosthetic devices based on lifestyle and physical stature intrinsically broadens the range of device models susceptible to high failure rates. Finally, the capital market surrounding the prosthetic industry elucidates the consumer demand of prosthetic device engineering. The value of superior reliability analysis methods is further fixed in the time and capital investments devoted to physical testing of prostheses.

While the market for healthcare products and devices is relatively cost-insensitive to manufacturer pricing structure, the financial backlash from device failure is exorbitant. The following generalized model provides a relative scale of cost implications operating within the healthcare industry: cost of preventing a defect before it occurs (1), cost of correcting a defect before it reaches the customer (10), cost of correcting the defect after it reaches a customer (10,000). VEXTEC technology enables presumed failure localization throughout the device development and prototype phases. The sound detection of component failure will therefore have a resounding impact on financial repercussions throughout the manufacturing supply and design chain.

Physical testing for medical devices is a time consuming, expensive and crudely defined process. Medical devices undergo several iterations of real stress simulation in labs to understand modes of failure and mean times. Making alterations to the design or material is costly as the whole reliability testing process has to often be physically repeated.

Methodology

A test case to showcase, the application of VEXTEC's tools to the medical device industry was designed. This involved modeling a kneeling problem found in literature1. Finite element analysis on the knee joint could not be completed due to insufficient data. Next, shock absorber in the knee joint that would get much of the stress from normal walking was analyzed using finite element analysis to find stress points in its design. This allowed for a better chance at showing the power of VEXTEC's software in medical devices. At this time, the analysis has been partially complete, but the specifications have been documented for future work.

An Endolite ESKMKL knee prosthesis was used in this analysis problem. A system level reliability analysis was performed to identify components with high failure rates. This analysis indicated that the strut sub-system had the maximum failure rates. The strut sub-system, when further analyzed indicated that the bolt and the trunnion were the frequently failing components. These components were analyzed using finite elements and VPS-MICROTM to determine the minimum life and scatter in real-life usage. FEA analysis was performed on the trunnion for stresses and deformation Since

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the bolt interfaces with trunion the forces are equal and opposite. The finite element results were used as inputs for the VPS-MICROTM for reliability life analysis. The knee components were made of titanium with a Young’s modulus of 14.8E3 ksi. Failure in trunnion and bolt over a five year period when used by a 220 lb man for jogging was analyzed using FEA analysis and VEXTEC tools. Details of the stress simulation are left out for proprietary reasons

ResultsTechnical

In forming a test case to show the power of VEXTEC’s software in the medical device industry, a knee prosthesis is taken and analyzed.1 Components identified to be possible failure points are shown in Figure 1. The trunnion and bolt upper attachment for the strut assembly were analyzed with finite element analysis and VPS-MICRO for further results. Details of VPS -MICRO and VPS-VIEWz have been left for propriertary reasons

Figure 1: Knee prosthetic system with sub-systems analyzed in VPS-VIEWz

Figures 2,3 & 4 are outputs of VPS Viewz Simulation. Figure 2 shows how the reliability of the prosthesis degrades over 5 years. It is apparent that the reliability decreases almost linearly with respect to time. The analysis is run to simulate 5 years of general use of a knee prosthesis. Figure 3 is a Pareto chart that shows the relative failure rates of each component in the strut assembly outlined in Figure 1. Each colored bar represents a relative reliability for a part of the strut assembly, so it is suggests the reliability of the bolt is lower than the trunnion, which is lower than the reliability of the Pneumatic Swing Phase Control. Figure 4 shows the number of failures in 5 years for the

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strut assembly. The y-axis gives the number of failures for each part outlined on the chart. It shows that the bolt and the trunnion have high failure rates, which in turn reduces the reliability of the strut assembly. These failure rates as a whole reduce the overall reliability of the knee assembly over 5 years.

Figure 2: System Reliability Chart for Knee Prosthesis System over 5 years. In the figure the x-axis gives time in years, and the y-axis shows reliability

Figure 3: Pareto Chart showing relative failure of components in the Strut Assembly

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Figure 4: Number of Strut Assembly Failures in 5 Years

Figure 5 shows the mesh and boundary conditions for the finite element model of the trunnion. The light blue marks are where the mesh was constrained from motion in the vertical direction. A pressure load is placed on the bottom to simulate a jogging step for a 220 lb man. The subsequent VPS-MICRO data for the bolt upper attachment is derived from the trunnion data, because the stresses are assumed to be opposing those forces on the trunnion. Figure 6 shows deformation for the trunnion. The scale in Figure 6 contains results in meters. Note that visual deformation in the figure is magnified many times what the numerical results show. Figure 7 gives the von Mises stress contours for the component in Pascals, and Figure 8 shows contact stresses at the bolt trunnion interface, also in Pascals. All finite element analysis was performed using MSC/PATRAN and MSC/NASTRAN.

The finite element analysis was performed by Jason Deaner, mechanical engineering department. The analysis in VPS-VIEWz and VPS-MICRO was performed with the help of VEXTEC. The output data from finite element analysis is used in VPS-MICRO so that long-term reliability data can be simulated. Important data from FEA is mostly based on stress data. This allows linear static results to contribute to cyclic reliability analysis. While the only FEA performed was for the trunnion, this same process would need to be completed for the rest of the components in each subsystem. When the reliability analysis in VPS-MICRO is completed for all parts, overall reliability can be derived from the results, and problem-areas can be identified and modified for improved reliability of the system as a whole.

Figure 5: Mesh and boundary conditions for trunnion

Figure 6: Deformation results for trunnion. Deformation is shown in meters.

Figure 7: Von Mises Stress Contours for Trunnion. Stresses are shown in Pascals

Figure 8: Von Mises Stress Contours for bottom of ring on Trunnion. Stresses are shown in pascalsFigure 9 shows the VPS-MICRO™ output for the bolt. The simulations have assumed as

weight of 200 lbs for the subject using the prosthetic. The effect of the prosthetic in jogging condition is evaluated assuming the person jogs 3 times a week. In the first year 7 of 1000 failures will occur in the bolt. In the 2nd year there will be 5 failures, 3 in the 3rd, 2 in the 4th and 2 in the 5th year. 19 bolts are predicted to fail in the first 5 years. However 981 are expected to last over 5 years.

Figure 9: Simulated Fatigue Testing of Bolt

Figure 10 shows the VPS-MICRO™ output for the trunnion. As in the previous case, the simulations have assumed that a person of 200 lbs uses the prosthetic. The effect of the prosthetic in jogging condition is evaluated assuming the person jogs 3 times a week. In the first year 4 of 1000 failures will occur in the bolt. In the 2nd year there will be 4 failures, 1 in the 3rd, none in the 4th and 1 in the 5th year. 10 trunnions are predicted to fail in the first 5 years. However 990 are expected to last over 5 years. Thus the simulation effectively identifies the part in the assembly that is most likely to fail and predicts the number of failures over a period of time. Such inputs would be handy for the designer as areas with higher probability of failure can be modified to increase reliability before a medical device in put into the market.

Figure 10: Simulated Fatigue Testing of Trunnion

Economic ConcernsMarket AnalysisThe health care equipment and supplies market consists of manufacturers of health care

equipment and supplies. Market value refers to the revenues generated through the sale of disposable equipment such as syringes, catheters, electrodes, sutures, bandages, implantable prostheses and orthotics and prosthetics; technical aids such as hearing aids and wheelchairs; ophthalmic equipment such as eye glasses, contact lenses and ophthalmoscopes; in vitro diagnostics; and other equipment such as imaging equipment and films and equipment for radiotherapy, dialysis, endoscopy, anaesthetics, etc.14

The US is the world’s largest health care equipment and supplies market, generating 46.3% of global market revenues. Europe has the second largest regional market, accounting for 34.1% of the global market’s value. The United States health care equipment and supplies market grew 4.7% in 2005 to reach a value of $86.3 billion. The market is forecast to have a value of 105.3 billion by 2010, an increase of 22.1% since 2005. Unhealthy lifestyles and an aging demographic are leading to higher incidences of chronic disease, whose diagnosis and treatment is a driver of demand for medical equipment and supplies. Health care spending is also increase and the introduction of Medicare Part D scheme makes medical treatment accessible to a broader socio-economic spectrum of patients, which will boost industry revenues going forward. As a result, healthcare expenditure is at an all-time high and growth is set to continue. This will raise company revenues through increased demand for diagnostic and treatment equipment.

According to Ossur’s Annual Report for 2006 prosthetics manufacturing is a $500 million sector of the $200 billion medical device market dealing with the production and fitting of artificial limbs. The reasons for amputation include vascular diseases such as arteriosclerosis (40%) and ailments resulting from diabetes (34%). Other reasons for amputation include cancer (20%) and trauma (6%). The majority of people losing limbs are older than 50 years, and with the percent of the population over the age of 50 increasing at 2.5% every year, the market will increase. The growth rate is projected to be 3-5%.14 Growth in the prosthetic industry for artificial limb is high due to wars, diabetic amputations and frequent replacements. 2 The two largest prosthetic companies are Otto Bock and Ossur.

Ossur suffered a voluntary recall in March 2006 of their Total Knee prosthesis due to a pin defect in 1% of products. With Ossur having a product liability insurance cap of $20 million, the result of this design defect after introduction has resulted in a loss in revenue in addition to damaging their customer reputation.3

In a study funded by the U.S. Department of Education, the market demand for reliable prostheses rally 27 million persons (or ten percent of the U.S. population) that are disabled and rely on assistive medical devices.18 As one of the most significant third-party providers of prosthetic devices, the Veteran's Association also conducts comprehensive prosthetic market forecasts. Based on prostheses demand adjustments within the aging baby-boomer veteran population, as well as returning soldiers from the Global War on Terrorism, the overall increase in capital investment for prosthetics spans a 1.12 billion dollar allocation in 2006 to a projected 1.34 billion dollar obligating in 2008 . Additionally, there is an initiative to increase healthcare services allocation by 29.3 billion dollars in 2008. Approximately 1.453 billion dollars will be designated to the improvement of durability of prosthetics and sensory aids. Finally, the projected cost of repairs to prosthetic appliances also expected to increase from $89 million in 2006 to $103 million in 2008. 19 The average life of an artificial limb is 3-5 years.2

Otto Bock’s C-Leg is a $50,000 artificial leg that is one of the two prosthetics Iraq and Afghanistan veterans with above-the-knee amputations will be receiving at the Walter Red Medical Center in Washington. The leg allows amputees to walk naturally, climb stairs and return to a normal life. The microprosser-controlled C-Leg is also used as a part of the rehabilitation program because of its ability to adapt functionally as patients progress through rehabilitation17.

In a testimony to the House Committee on Veteran’s Affairs, the CEO and President of Otto Bock Healthcare Mr. Bert Harman says “Otto Bock is proud to be a

(2) The Medical & HealthCare Marketplace Guide, 18th Edition, 2003, Publisher: Dorland Healthcare information.(14) www.datamonitor.com(3) “Defective pin leads Iceland Company Ossur to voluntarily recall Total Knees. Hospital Materials Management. 31.6 (June 2006): 7(1). InfoTrac OneFile. Thomson Gale.(17) Amputees demonstrate leg issued to returning veterans. The Montgomery Advertiser. April 6, 2007.(18) United States Dept. of Education. Natl. Inst. on Disability and Rehabilitation Research. Assistive Technology and Information Technology Use and Need by Persons withDisabilities in the United States. By Dawn Carlson and Nat Ehrlich. Aug. 2005. 2 Mar. 2007. http://www.ed.gov/(19) United States Dept. of Veteran Affairs. Fiscal Year 2008 Budget Estimate. 2 Mar. 2007 http://www.va.gov/budget/summary/VolumeIMedicalPrograms.pdf.

http://www.datamonitor.com/

partner with the VA and DoD to meet the needs of the modern military and veterans. This public-private collaboration is essential to developing high-quality prosthetics to serve all persons with limb loss. While Otto Bock is the largest prosthetic manufacturer in the world, we are a relatively small, privately held company with limited research resources. Expanded collaboration with the private sector is essential to continued development of technologies that will significantly improve the lives, health, and productively of our military and veteran amputees, while also assisting Medicare beneficiaries and other amputees outside of the VA and DoD systems.” 1 It was announced that the Defense Health Program is fully funded with a $19.2 million to improve amputee care at Walter Reed Army Medical Center. 15

Prosthetic and orthotic rehabilitation is unlike other medical care, in that it is primarily concerned with function rather than pathology. Historically the highest growth in the prosthetic market has been in times of war. Total number of lower limb amputations is estimated between 130,000 and 145,000 in the United States.

Much research in the prosthetic industry is devoted to materials and progressive design. For above the knee prosthesis a number of methods are used to maintain the balance between flexibility and stability, including purely mechanical devices, pneumatic devices and hydraulic devices. Material Weight and flexibility is another area of research for above the knee prosthesis. Traditionally used materials like wood or hard plastic are heavy and are more likely to cause blisters and infections. Newer models tend to use carbon composites, acrylic resins, titanium and aluminum.

For below the knee prosthesis, the VA as of 2002 didn’t pay more than $4000. The price ranged from $4000 to as high as $18000 depending on the complexity and functionality of the below the knee prosthesis.2

There are approximately 3300 licensed orthotists and prosthetists that are trained to fit custom prosthetics to patients. As of 2002, there were 100 manufacturers registered with the Food Drug Administration.2

Physical testing for medical devices is a time consuming, expensive and crudely defined process. Medical devices undergo several iterations of real stress simulation in labs to understand modes of failure and mean times. Making alterations to the design or material is costly as the whole reliability testing process has to often be physically repeated.



Benefit AnalysisVEXTEC’s technology can simulate the reliability of any part in a complex

system, this process is called reliability chain management. In industry application the VEXTEC tools can be used to allow for the estimation of warranty cost, reduce recalls and failures, allow for better designs, component or vendor selection, reduce testing and lead to faster market induction of new designs. VPS-VIEWz can assess the reliability of systems, and identify weak sub-systems. VPS-MICRO performs detailed analysis on the components that have low reliability.

The poor reliability of a medical device can lead to high costs to the manufacture, wasted time, customer inconvenience and eventually poor customer reputation. The causes of poor reliability are due to improper design, improper materials, manufacturing errors, assembly and inspection errors, improper testing, improper packing and shipping, user abuse and misapplication. VEXTEC’s tools can be used to analyze the design, select appropriate materials, and improve testing methods. For a medical device manufacturer, higher reliability of the device and appropriate warranty selection will result in an increase in customer satisfaction and customer reputation.

Design of medical device designer has two primary functions: 1) Devise new products uniquely addressing a problem. 2) To provide improvements to existing products. In the medical device field ideas for innovations come from observations made by marketing personnel on hospital visits, discussions with doctors, surgeons, and other medical professionals. According to the ‘biomaterial science and engineering series’, medical device design include the following major steps:

1) Analyze the problem and the hypothesized solution 2) Make a preliminary design for concept evaluation3) Consider material options4) Conduct a feasibility assessment5) Build a prototype and do lab testing6) Produce a fully detailed design7) Laboratory testing8) Consider different manufacturing options and methods of assemble9) Quality assurance testing, and clinical trials. 13

From literature review and conversations with prosthesists and orthopedics it was found that the state of physical testing in the prosthesis industry is time consuming, crude and costly. The extent of testing regulations depends on the class of the medical device. Typically in the design phase prosthetic prototypes undergo real life like stress simulation



in a laboratory based environment to test for modes of failure and mean time between failure. Based on the observations, changes are made to the prototype if necessary and stress simulations are carried on each time. Once the prototype is finalized, a fully detailed design is built and tested in laboratory conditions. Once it passes the laboratory testing, the prosthesis undergoes clinical testing before it is ready to go to the market.

Testing of a medical device is defined as subjecting a device to conditions that indicate its weakness, behavior characteristics and modes of failure. It provides pertinent information to the development team of the device and is a continuous operation during the development cycle. There are three reasons for testing for medical devices which include basic information, verification and validation. 10

The basic information testing allows for vendor evaluation, vendor comparison, and component limitability. While the validation proves that the subsystems and system requirements are met by the device. Hardware testing is performed twice in the development cycle. Once immediately after the design phase to evaluate the robustness and reliability of the design and then after production of customer units begins to evaluate manufacturing process.

Optimization of mechanical reliability occurs with timely elimination of components or assemblies of components through preventative maintenance before the failure rate unacceptably high levels. With VEXTEC tools optimization of mechanical reliability will be possible for prosthesis manufacturers. Electronic reliability will be soon become apart of VEXTEC’s core competency this will allow VEXTEC to expand to other markets in the medical device industry.

FDA and other regulatory body considerationsA medical device includes a wide variety of products; things as simple as a tongue

depressor or as complex as an ocular implant. These devices are regulated by governmental bodies as well as standards organizations. Regulation of medical products is determined and enforced by the Food and Drug Administration (FDA) in the U.S. and the European Commission (EC) in Europe. Also, many products in the prosthesis market and other medical devices adhere to standards set by the International Organization of Standards (ISO).

The FDA originally regulated issues only related to food and drugs, but towards the latter part of the 20th century it began to focus on medical devices as well8. The FDA enacted the Medical Device Amendments to the FFD&C Act in 1976, which purpose was ensuring that medical devices were safe, effective, and correctly labeled for use8. From



this act, the Good Manufacturing Practices (GMP) was created in 19788. The GMP is a quality assurance program which controlled manufacturing, shipping, and installation of medical devices. These acts and programs allow the FDA to inspect a company's operations and enact punishment where needed. If a company is in any way involved with manufacture or preparation of a medical device, they must register with the FDA. This registration must occur concurrently with the initial manufacture of the device and must be renewed yearly for as long as the device is on the market8. Foreign firms do not have to register with the FDA, but they must submit a listing of all products including both product specs and copies of product advertising and labeling8.

The FDA separates medical devices into 3 categories. A 'Class I' device is a non-life sustaining device, which upon failure does not pose risk to the life of the patient or others8. These devices are not required to adhere to performance standards, but still must adhere to registration, the GMP, and listing with the FDA8. Some Class I devices also must adhere to pre-market notification (510(k)), but most devices are deemed exempt1. Also, some of the Class I devices, such as tongue depressors and stethoscopes, can become exempt from even these small requirements9. A 'Class II' device is also non-life sustaining, but is required to comply with all the standards for Class I as well as moderate performance standards, including mandatory pre-market notification (510(k))8. The purpose of the pre-market notification process is to provide manufacturers the opportunity for rapid market approval by proving their devices are "substantially equivalent" to a currently marketed device8. Some examples of Class II devices are powered wheelchairs, infusion pumps, and surgical drapes9. The most stringent category, 'Class III', includes all devices which are either life-sustaining or their failure is life-threatening8. All devices in this category must submit a Pre-Market Approval Application (PMAA)8. This process is long and complicated, and has caused some dissatisfaction within the medical device industry. The PMAA process includes failure mode analysis, animal tests, toxicology studies, and finally human clinical trials8. Some examples of Class III devices are heart valves, pacemakers, balloon catheters, and even silicone breast implants9.

The International Organization for Standardization (ISO) is a regulatory body which imposes product standards (including medical device products) covering all European and American products8. The ISO began in Europe, but has been adopted by the United States Department of Defense and many major U.S. corporations8. Although these standards are not enforced by any national laws, ignoring them is not a viable option. A product lacking ISO standards approval would be severely devalued in the



marketplace. In fact, major customers may require ISO certification as a requirement to even initiate business discussions8. The ISO 9000 series of standards lay out a quality management system to judge how well a business delivers a consistent quality product1. The passage of these standards by U.S. companies has helped FDA approval processes move along more speedily. ISO 9000 standards require design reviews, which include analysis of potential product misuse, overstressed parts, and redesign of weak areas versus high reliability parts8. They do not however require Finite Element Analysis (FEA) in the design reviews of prosthetic devices. The ISO 9001, a section of the ISO 9000 series, is very similar to the Good Manufacturing Practices (GMP) of the FDA8. The European Norm (EN) 46001 standards provide particular requirements for medical devices, specifying the general requirements stated in the ISO 9001 standards8.

Since most prostheses, especially leg prostheses, are Class I devices, there is little difficulty in the FDA process for companies manufacturing these products. However, almost all major prostheses manufacturers adhere to ISO and EN standards on medical devices. Therefore, VEXTEC should focus less on getting its methods approved by the FDA and focus more on the ISO. The ISO is less stringent in its standards than the FDA, and the process of approval is much quicker. If VEXTEC could get its methods approved by the ISO, this would provide a boost to their brand image and would encourage companies to use their services in adhering to ISO standards. Also, being accepted by the ISO would boost VEXTEC's chances of being approved by the FDA, as has been shown with medical devices themselves.

Marketing

Capabilities AnalysisVEXTEC is a product leader and their core competency is the modeling physics

of failure. VEXTEC is an industry leader in developing techniques to model the physics of failure down to the microstructure of the material and further using this expertise for statistical reliability analysis. Their main product is VPS-VIEW, which performs comprehensive reliability chain management that allows the user to evaluate his methods and procedures to improve the reliability of his designs.

VEXTEC's center of gravity is primarily based in the technology discipline and customer intimacy. However, the reason VEXTEC currently excels in customer intimacy may not extend over into the health-care market. VEXTEC has developed personal



contacts in the aerospace and automotive industries. They have a relationship with these industries and thus have earned a level of confidence in their product. VEXTEC needs to develop that same relationship and confidence in the healthcare industry.

VEXTEC's services represent the cutting edge in terms of reliability analysis, but are completely absent from the medical device industry, which has relatively crude reliability analysis and relies on expensive physical testing. VEXTEC must show the medical device industry that its services will improve the quality of medical devices as well has help these manufacturers save money on physical testing and design. The demonstration of feasibility shown in this design project is the first step in convincing these medical device manufacturers to upgrade their reliability analysis techniques.

Competitive AnalysisRidgetop Group is a somewhat similar company to VEXTEC, and some of their

technology is similar to VEXTEC's electronic application. Like VEXTEC, Ridgetop is very small, are mainly funded by SBIR's and STTR's, have experience in the aerospace industry, and have a low operational strength. They focus specifically at the reliability of electronics, and make a product for semi-conductor reliability which could potentially be brought to the medical device market. However, there is little need for electronic reliability analysis in the medical device market, at least not the type that either VEXTEC or Ridgetop Group can provide. In these medical devices there is little stress on the electronic parts, vastly less than in automotive or aerospace applications. Some newer prosthetics do have onboard electronic systems, and this could be a potential market, albet a small one.

Relex provides reliability software to a wide range of engineering applications, as well as accompanying consulting and training services. Relex has been delivering reliability services for over 20 years. Their software performs statistical analysis through FMEA (Failure Mode and Effects Analysis) and Fault Tree Analysis. However, their software and services do not include both top-up and top-down approach provided through the physical modeling by VEXTEC. Essentially, Relex is more of a substitute than a competitor to VEXTEC, because their software methods are based off educated guesses about the product rather than scientifically modeled virtual simulation. Also, Relex is more of an operationally focused company than VEXTEC or Ridgetop Group. They have experience with some of VEXTEC's own customers, such as Lockheed Martin.



Reliasoft sells a number of reliability software solutions, all of which use statistical analysis techniques similar to Relex. Reliasoft presents their products in more of a commoditized manner than Relex, with more than 8 different product libraries. They are also a younger company than Relex, being founded in 1992. Reliasoft has a very large and diverse customer base in a multitude of industries, from aerospace to semiconductor firms and including medical device manufacturers. Consulting relationships may include complete reliability programs, test and experiment design, data analysis, theoretical development, and equipment reliability assessment.

Value PropositionVEXTEC’s reliability analysis solution would allow for reduction in the cost and

time associated with physical testing. Instead of using a generalized testing methodology, VEXTEC’s techniques analyze the design for stress distributions to identify parts of the design that are most likely to fail. A designer can then modify the material and the assembly of the design to avoid stress concentrations and increase the overall life and reliability of the design. Once an optimum design has been built, physical testing can be performed for quality assurance purposes. Using VEXTEC’s solution in the design phase would allow for less physical testing iteration in reaching for an optimal design and thus reduce the cost of testing and allow for faster market induction. The solution would also be handy in the future evolution of medial devices, as any proposed material or design changes as they can be easily be incorporated in the simulation and assessed for reliability

Customer AnalysisOtto Bock Holding GmbH & Co. KG is private company comprised of three core

divisions: HealthCare, Plastics, and Information and Communications Technology. The Plastics division works mainly in Europe with the automobile industry as its customer for foams and plastics. VEXTEC has prior experience and reputation in the automotive industry could be of some interest Otto Bock executives as some revenues come from its automotive parts division. This would lead to a common understanding between VEXTEC and Otto Bock. Also, Otto Bock has stated that they do indeed perform Finite Element Analysis, a necessity for VEXTEC's technology. They have been receptive to the technology so far in phone interviews.

In addition, Otto Bock is currently partnering with VA and DoD to improve amputee care for returning veterans from Iraq and Afghanistan. This could be a benefit



to VEXTEC as they already have an understand of how to approach the DoD. Ossur voluntarily recalled Total Knee models due to faulty pins located in the axis

of the knee in 20061. This is a glaring example of what can happen if reliability analysis of the product is not properly performed. Ossur is looking for many different ways to improve their reliability analysis and the overall reliability of their products, and VEXTEC could help in this regard, and consequently help prevent similar issues in the future. Ossur has also been receptive to VEXTEC's technology in phone interviews.

Conclusion

A test case was evaluated to assess the feasibility of VEXTEC’s simulations in the medical device field. An Endolite ESKMKL knee prosthesis was analysed for reliability using a top down approach. Stesses were simulated for a 220 lb jogging man. The strut assembly was analysed for failure in bolt, trunnion and the Pneumatic Swing Phase Control using VPS Viewz. The bolt and trunnion were found out to have high failure rates. An FEA analysis was performed on the trunnion and the VPS-MICRO was used to asses the long term reliability of the components (Bolt and Trunnion). Failure rates for the first 5 years were quantified. Similar analyses would need to be performed on every component of the prosthesis to quantify the overall reliability and areas of predicted failure. The results show the feasibility of VEXTEC's tools to analyze the reliability for a knee prosthesis. The process enables principal component analysis and top down design reliability. Problem areas can then be identified for detailed modeling and improved design.

The economic and marketing analysis of the medical device industry shows that the prosthesis segment is ideal for VEXTEC to launch into. The best way to receive recognition and funding from the DoD would be to partner with Otto Bock for a feasibility analysis to show the value of VEXTEC tools in the medical device industry. VEXTEC should also focus on getting recognition in Europe with ISO Standards. This will help give credibility to the VEXTEC brand name so eventually their software can be recognized as a valuable tool for the FDA, who are much slower to change design control policies.

Future Recommendations



Technical VEXTEC should perform reliability analysis on other types of prostheses and medical

devices, both mechanical and electronics based. A retrospective study should be performed to test the reliability of a design whose failures have been observed over a period of time. The results given by VPS MICRO and other techniques can then be compared to the actual results to better perform a fesibility analysis of VEXTEC’s techniques in the medical device sector. Otto Bock is currently issuing the C-Leg to all Iraq and Afganistan veterans with above- the- knee amputations. This could be the perfect opportunity to collaborate with Otto Bock to show the Army and/or DoD (Department of Defense) a feasibility study of the VEXTEC tools in relation to the C-Leg. Improved understanding of the reliability uses will save Otto Bock in maintenance and repair costs and lower the cost of the insurance provider of replacing the prostheses.

MarketingVEXTEC should try to develop meaningful relationships with medical device

manufacturers to better understand the needs of the potential customer. This can be accomplished from two separate strategies. First, the bottom-up strategy would involve contacting design engineers first. This is the approach this research group has taken in contacting the prosthesis manufacturers. The process involves selling the engineers on the validity of the technical aspect of VEXTEC's value proposition, namely the microstructure analysis and implementation of FEA data. Once the engineers are convinced of the technical usefulness of the technology, they will refer VEXTEC to upper management for further review. From this research group's experience, it has been easy to contact the engineers and convince them of the usefulness of the technology, but the strategy has had some resistance in bridging the gap between these engineers and upper management. Further work is needed in getting these engineers to gain the attention of their upper management. Perhaps one solution would involve having the engineer set up a conference call that would include both his manager and VEXTEC personnel.

Second, the top-down strategy would involve contacting upper management initially. VEXTEC would try to sell upper management on the Reliability Chain Management (RCM) and the warranty enhancement aspects of its value proposition by providing a feasibility analysis, then the management would refer to their engineers for



assistance in understanding the more technical side of VEXTEC's value proposition. This method has yet to be tried by this research group, and is worth an attempt.

In order to gain attention in the medical device industry, VEXTEC will need a strong brand name. In order to obtain this, VEXTEC should first get published in medical device industry magazines and journals, and also attend the industry trade shows, prosthetic industry trade shows in particular. Aaron Fitzsimmons, a contact previously interviewed by this research group, would be a good contact to determine which trade shows to attend.

In terms of regulatory bodies, VEXTEC would be better served by concentrating on the ISO first instead of the FDA. The ISO is seen by manufacturers as a stepping stone to FDA approval, and their standards are easier and most likely more agreeable to the virtual testing that VEXTEC provides. If VEXTEC can get the ISO to approve their methods for their testing requirements, this would lead to a more favorable treatment from the FDA as well.



Appendix

References(1) Magnissalis, Evangelos Et Al. “Prosthetic Loading During Kneeling of Persons with Transfemoral Amputation.” Journal of Rehabilitation Research and Development 36.3 (1999): 1-15.(2) The Medical & HealthCare Marketplace Guide, 18th Edition, 2003, Publisher: Dorland Healthcare information.(3) “Defective pin leads Iceland Company Ossur to voluntarily recall Total Knees. Hospital Materials Management. 31.6 (June 2006): 7(1). InfoTrac OneFile. Thomson Gale.(4) Reliable design of medical devices. Richard Fries. . Boca Raton : CRC/Taylor & Francis, 2006.(5) http://www.fda.gov/bbs/topics/NEWS/2006/NEW01506.html (6) http://tools.euroland.com/arinhtml/is-ossr/2006/AR_ENG_2006/index.htm(7) Handbook of Medical Device Design. Richard Fries. Marcel Dekker, Inc. 2001(8) David Hill, Design Engineering of Biomaterials for medical devices, 1998, John Wiley & Sons.(9) The Medical & HealthCare Marketplace Guide, 18th Edition, 2003, Publisher: Dorland Healthcare information.(10) Design of Biomedical Devices and Systems. King, Paul. Richard, Fries. Marcel Dekker, Inc. 2003. (11) Fries, Richard C., Medical Device Quality Assurance and Regulatory Compliance. Marcel Dekker, Inc. New York 1998(12) http://www.fda.gov/cdrh/devadvice/3132.html(13) David Hill, Design Engineering of Biomaterials for medical devices, 1998, John Wiley & Sons.(14) www.datamonitor.com(15) www.defenselink.mil/news, July 26,2004(16)http://veterans.house.gov/hearings/schedule108/jul04/7-22-04/bharmand.html(17) Amputees demonstrate leg issued to returning veterans. The Montgomery Advertiser. April 6, 2007.(18) United States Dept. of Education. Natl. Inst. on Disability and Rehabilitation Research. Assistive Technology and Information Technology Use and Need by Persons withDisabilities in the United States. By Dawn Carlson and Nat Ehrlich. Aug. 2005. 2 Mar. 2007. http://www.ed.gov/

(19) United States Dept. of Veteran Affairs. Fiscal Year 2008 Budget Estimate. 2 Mar. 2007 http://www.va.gov/budget/summary/VolumeIMedicalPrograms.pdf.

http://www.defenselink.mil/news


http://www.fda.gov/cdrh/devadvice/3132.html

http://tools.euroland.com/arinhtml/is-ossr/2006/AR_ENG_2006/index.htm

Innovation Work Bench

Ideation Process Project Initiation

Project Name:Reliability Analysis of Above the Knee Prosthesis

Project timeline: Concept should be found and implemented by April, 2007.

Project team:Aashish BapatApril BoldtGrainger GreeneJason DeanerDani Shuck

Innovation Situation Questionnaire

Brief description of the situation

Redesign the existing reliability analysis protocol to cater to the needs of the medical device manufactures. Reduce cost and time and increase quality.

Improve productivity

Improve convenience

Increase reliability

Reduce cost

Reduce time wasted

Detailed description of the situation

Supersystem - System - Subsystems

System name

SocketKnee systemShank Foot-ankle system

For the socket, the problem is biocompatibility, stress shielding, and fatigue failure.

For the knee system, the problem is heat and fatigue failure.

For the shank, the problem is fatigue failure, and deformation.

For the foot-ankle, the problem is fatigue failure, compression loading, traction and stability.

System structure

The socket assembly consists of the following elements:• socket• stump• knee system

Supersystems and environment

Other parts of the socket:• titanium screws• pelvic belt or silesan bandageOther systems located nearby:• stump• knee systemSystems with similar problemsSimilar problems exist in many other areas where weight and mechanical strength are critical issues.

Input - Process - Output

Functioning of the systemReplace the support and function of human leg.System inputsSocket inputs:• weight• fluid

System outputsSocket outputs:• stability• support• translation to knee

Cause - Problem - Effect

Problem to be resolvedSimulate the average and first fatigue failure of above the knee leg prosthesis to reduce the fatigue failure and cost of product testing.Mechanism causing the problemThe socket is the stable attachment of leg prosthesis to stump. It must be biocompatible and have mechanical compression strength. Undesirable consequences if the problem is not resolvedFailure of leg prosthesis would cause injury to subject.Other problems to be solvedFunction of leg prosthesis as replacement of limb.

Past - Present - Future

History of the problemAfter World War II the veterans needed artificial limbs to replace war injuries. These must function and stabilize the subject.Pre-process timeBefore attachment customization and loading of subject.Post-process timeAfter failure of prosthesis.

Resources, constraints and limitations

Available resourcesTechnical Informational resources• VEXTEC• prosthesis manufacturer• Aaron Fitzsimmons

Allowable changes to the system• material • manufacturing• system designConstraints and limitations• stability• patient compliance• low failure rate

Problem Formulation and Brainstorming VEXTEC Diagram 1

11/30/2006 5:53:32 PM.

Find an alternative way to obtain Socket that offers the following: provides or enhances Knee System is not influenced by Biocompatibility and Weight.

Find an alternative way to obtain Foot-ankle system that does not require Shank.

Find an alternative way to obtain Shank that offers the following: provides or enhances Foot-ankle system does not require Knee System.

Find a way to eliminate, reduce, or prevent Biocompatibility.

Develop Concepts

1. Combine ideas that perform the same function

-analyze the stresses of the above the knee leg prosthesis

-focus on different types of gaits

-look at moving parts in above the knee leg prosthesis

2. Combine known systems to develop a concept

-find the maximum stress point of a pin in the knee joint

-use principles of biomechanics and known anthropometric data tables to develop the design

3. Simplify the concept

-make free body diagram using simplified stick model

-analyze the kneeling position as it is known to create the maximum stress

Evaluate ResultsMeet criteria for evaluating concepts

Reliability analysis program would would work best if the FEA analysis identifies a maximum stress point in the knee joint

Reveal and prevent potential failures

Through FEA analysis is necessary because a simulation is only as good as its inputs

Dimension of knee must be thoroughly calculated as they determine the stress outputs

Plan the implementation

Compare the results of the reliability analysis simulation to physical testing results in the paper

Use the results as a case study for further complicated medical device simulations

Analyze the physical testing methodology currently used in medical device industry to identify cost saving and quality improving applications for VEXTEC simulation

Documents

Technical Results:research.vuse.vanderbilt.edu/srdesign/2006/group11/Fi… · Web viewEurope has the second largest regional market, accounting for 34.1% of the global market’s