Additive Manufacturing for Personalised Knee Systems Cyient

Additive Manufacturing for Personalized Knee Systems Driving better outcomes for patients as well as healthcare providers

Contents

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Abstract

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Introduction to Knee Replacement Systems

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Standardized Knee Systems

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Personalized Knee Systems for Better Results

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Additive Manufacturing: Reengineering Medical Procedures

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Multi-Dimensional Benefits of Additive Manufacturing

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Regulatory View on Additive Manufacturing

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Partnering with a Vendor: Overcoming Challenges in Personalizing Knee Systems through Additive Manufacturing

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References

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Authors

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About Cyient

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Additive manufacturing enables increased value and facilitates enhanced patient satisfaction.

Abstract Medical devices companies across the world today are more focused than ever on developing innovative products for global orthopedic demand. This demand is driven by surgeons and caregivers to provide better clinical outcomes to patients and reducing hospital stay.

Conventional knee systems are standardized by various manufacturers and are approximations of patients’ knees, based on knee anatomy data collected in a specific geography. However, in recent times personalized systems have become increasingly appealing to manufacturers and marketers because of the value addition they provide. Personalized systems are built on the premise that each patient is unique.

They are designed very precisely to ensure that the alignment is personalized for each patient leading to reduced efforts at the time of surgery. This innovation will help meet the unfulfilled demand, especially in the emerging markets where patients are reluctant to opt for surgery.

Traditional manufacturing methods like CNC machining, plastic molding, and casting have a long lead time due to the involvement of activities such as tool design and development, and manufacturing trials.

Additive manufacturing can reduce this manufacturing lead time and result in improved patient satisfaction eventually.

There has been an unprecedented growth in additive manufacturing across the medical devices industry, leading to a significant level of investment and interest across the globe. It is poised to become one of the most valued forms of manufacturing. Scientists and engineers have made great strides in additive manufacturing creating prosthetics and instruments. Additive manufacturing approach is being deployed in pre-operative planning at hospitals along with imaging techniques for simulation of procedures.

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Medical device manufacturers must therefore consider moving beyond conventional manufacturing practices and leverage this innovation to bring high value solutions to market. This could prove to be a win-win situation for all stakeholders – manufacturers, healthcare providers, surgeons and end users – in terms of lower costs, faster time to market, and improved results in personalized orthopedic therapies.

Introduction to Knee Replacement Systems Knee is one of the most complicated joints in our body. The knee joint is a hinge joint comprising of two joints between the bones of the leg. The most important joint is between femur – the thigh bone of the upper leg, and tibia – the shin bone of the lower leg. The smaller joint is located between patella—the kneecap, and the femur. The articular cartilage is the smooth, tough tissue that covers the ends of the bones, and facilitates smooth sliding over each other. The synovial fluid, produced by the synovial membrane over the other surfaces of the knee joint, lubricates the joint, and reduces friction.

Many factors such as loosening of femoral and tibial components, sacrificed or torn ligaments and mobile bearing components can aggravate the wear rate of the bearing surface, increasing the risk of osteolysis1. If articular cartilage is damaged or worn to the extent that the ends of the bones rub or grind against each other, the flexibility and articulation of the joint is significantly reduced. This leads to severe pain, swelling and stiffness. In such a scenario, the patient may be offered knee replacement surgery.

Knee replacement refers to surgery that helps alleviate the effects of severe knee damage.

Total knee replacement involves removal of

While standardized knee systems enable patients to lead a healthy lifestyle, they lead to complications in many cases.

damaged cartilage and bone from the surface of the knee joint and replacing them with an artificial surface. Cemented knee implants have been into existence for the past many decades. However, cementless implants have also been in existence for almost three decades now. In the long run, stability of implants is mostly dependent on bone growth into the implant; however, screws can be used to stabilize the implant.

Standardized Knee Systems Conventional knee systems are standardized by various manufacturers and are approximations of patients’ knees, based on knee anatomy data collected in a specific geography. Implants are selected by surgeons based on a patient’s knee shape and size, with necessary corrections made during the surgical procedure. In most cases, standardized implants help patients lead an active lifestyle, but some patients face complications after surgery. Typical causes of complications include2: • Uneven stress distribution in the femur The distal end of femur bears various forces generated by a patient’s weight and routine activities. In conventional surgical procedures, the distal end of the femur is squared off from its original round shape by planar cuts using cutting guides. This results in uneven stress distribution in the distal end of the femur, which may lead to loosening of the joint. The underlying reason is explained by physics: shapes with corners carry uneven stress distribution, while stress is evenly distributed in round shapes.

• Imperfect size of tibial implant Similar to the distal end of femur, the proximal end of tibia is also reshaped by planer cut using a cutting guide. The placement of the tibial tray plays a crucial role during surgery. Tibial tray is positioned using a stem configuration. During the procedure of tibial implant, stresses are 02

caused in the bone and if there is insufficient cortical bone for support, the bone can collapse leaving a void around the stem. If the surgeon is unable to find a perfect tibial implant size in the product portfolio, an oversized implant might damage the soft tissues and ligaments around the knee joint while an undersized implant might protrude into the cancellous bone which can cause post-surgical pain. To avoid these issues, surgeons need to have a perfectly sized tibial implant matching the patient anatomy.

• Wear of Ultra High Molecular-Weight Polyethylene (UHMWPE) The UHMWPE implant is placed over the tibial tray to avoid metal-to-metal contact between the femoral and tibial implants.

Unintended micro motion between the tibial tray and UHMWPE causes the UHMWPE to wear-out. Additionally, tiny particles created by joint between femoral implant and UHMWPE accelerate the knee joint failure.

In the worst cases, the bearing surface is completely worn out causing metal-tometal contact between femoral and tibial components, leading to discomfort and loss of motion. The wear particles of UHMWPE cause osteolysis, which might result in lack of mobility and pain. A revision surgery may be required to alleviate these painful conditions.

• Resurfacing of patella The insertion of the femoral implant might require resurfacing the patella to fit. In many cases, this causes post-operative pain. A personalized femoral implant with a sufficient patellar groove can avoid the need for resurfacing the patella, and help reduce the risk of post-operative pain.

Personalized Knee Systems for Better Results In recent times, the appeal of personalized knee systems has increased among surgeons and clinicians because they are designed on the principle that each patient is unique.

Personalized knee systems are more appealing as they are designed on the principle that each patient is unique.

Capture patient’s anatomy scan data

Build 3D geometry using standardized design as a base

Convert to STL format

Manufacture the system

Fig. 1 | Personalized knee system development and manufacturing process

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Implants and/or instrumentation in the knee replacement system are personalized depending upon various factors such as the patient’s age and bone density, disorder, type of surgery, surgeon’s preferences and other related factors. Since personalized systems are specific to patients, all designs are unique.

The design of each personalized knee system is highly precise, factoring in the patient’s unique anatomy and lifestyle. It results in an almost perfect fit, uniform stress distribution, and better load bearing capacity. It also helps the surgeon perform cuts in the bone and soft tissue exactly where they need to be.

As the alignment is personalized for each patient, reduced effort is required at the time of surgery to analyze alignment and proper positioning of the implant.

The typical process of producing a personalized knee system is illustrated in Fig. 1.

Key advantages of the personalized knee system over standardized systems include2: • Improved alignment • Decreased operative time • Increased patient throughput • Decreased instrumentation • Reduced risk of fat embolism and intraoperative bleeding due to minimal bone removal (i.e., no intramedullary canal reaming) • Decreased tissue loss • Shorter recovery • Reduced postoperative pain • Decreased incidence of infection • Lowered costs

Additive Manufacturing: Re-engineering Medical Procedures

Additive manufacturing is one of the techniques that helps meet this goal with justin-time response to a surgeon’s request. This benefit of additive manufacturing is not limited to the medical devices industry. For instance, in Formula One motor racing, engineers use additive manufacturing to manufacture parts in a highly proactive manner. “They can now analyze the car’s performance while it goes round the circuit and have a new part getting ready before it finishes the race,” said Graham Tromans, Principal and President of AM consultancy GP Tromans Associates3.

Additive manufacturing is the process of building components using 3D design data, by adding material to previously built areas in layers, as opposed to traditional methods such as subtractive manufacturing.

Additive manufacturing comprises several unique processes defined by a range of characteristics. Some of the standardized processes of additive manufacturing are mentioned in the Table 14.

In additive manufacturing, components are built using 3D design data, by adding material to previously built areas in layers.

These processes vary from each other in their strengths and flaws in the following aspects: • Material they can use – such as polymers or metals, waxes or paper • Build speed or the speed at which they can build parts • Accuracy of dimensions, and quality of the surface finish of components • Material properties of manufactured components • Cost of machine and raw materials • Complexity of operation, and the associated accessibility and safety Based on these varying aspects, these processes are applied in different areas including prototyping, tooling, direct part production, and repair of damaged parts.

• Design freedom, with reduced cost5 Producing parts with high complexity in geometry like patient specific knee implants is no longer a challenge. Additive manufacturing addresses this effectively, as it is independent of design complexity unlike conventional manufacturing methods.

Process

Materials

Market

1

Vat photopolymerization

Photopolymers

Prototyping

2

Material setting

Polymers, waxes

Prototyping, casting patterns

3

Binder setting

Polymers, metals, foundry sand

Prototyping, casting molds, direct part

4

Material extrusion

Polymers

Prototyping

5

Powder bed fusion

Polymers, metals

Prototyping, direct part

6

Sheet lamination

Paper, metals

Prototyping, direct part

7

Directed energy deposition

Metals

Repair, direct part

Table 1 | Standardized processes of additive manufacturing

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Multi-Dimensional Benefits of Additive Manufacturing Additive manufacturing offers multiple benefits for a wide range of markets. Some of the key advantages include:

Additive manufacturing has witnessed several advancements such as improved system process control, enhanced speed, cost effectiveness, greater accuracy and reliability, along with the introduction of better materials and/or changes to existing materials. These advantages have translated to a significant increase in the application of parts manufactured through this process.

Sl. No.

Due to its unique characteristics, additive manufacturing is best suited for producing applications that demand flexibility and quick development cycles, products belonging to high-value markets, as well as complex components. Manufacturers looking to avoid using tooling that increases costs can also rely on additive manufacturing and reduce cost per part substantially.

Additive manufacturing is independent of design complexity, and reduces lead time, as well as energy consumption and waste generation.

Cost Conventional production

3D Printing

Design complexity

Additive manufacturing market in the medical industry6 • The medical device industry, as of 2012, forms 16% of the total market size of 3D printing and is the third largest market.

• Services revenue, such as revenue from personalized solutions for end users who do not have the capital for a 3D printer, accounts for more than 50% of the total sales. The remaining 50% comes from printer and material sales.

Fig. 2 | Cost vs. design complexity 1400

$1260m

1200

• Reduced lead time The ability to manufacture the personalized knee systems without tooling enables device manufacturers to quickly deliver the device to surgeons according to their preferences, thus reducing the lead time that goes in relieving the patient’s pain.

• Precision in surgery Operating with patient specific surgical instruments is easier for the surgeon.

The instrument design can be optimized to match the specific patient anatomy and condition to enhance the overall functionality.

• Reduced energy consumption and waste generation Additive manufacturing methods help with energy and waste management. Using additive instead of subtractive methods results in lesser waste. The ratio of input material to output product material usage is very low compared to traditional manufacturing processes.

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$1000m 1000

Revenue

Additive manufacturing enables cost effective and low-volume manufacturing of personalized knee system by removing tooling and eliminating the need for large-scale investments.

800 600

$900m

24% CAGR

$672m $551m

$440m $353m 400 $282m $225m $180m 200 0 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021

Year Fig. 3 | Revenue forecast of additive manufacturing in the medical industry

Regulatory View on Additive Manufacturing7 The FDA is expanding its research efforts and capabilities required for reviewing innovative medical products. In fact, additive manufacturing is fast becoming the focus of the FDA’s practice of regulatory science — that is, the science of developing new tools, standards and approaches to assess the safety, effectiveness, quality and performance of FDA-regulated products. Two laboratories in the FDA’s Office of Science and Engineering Laboratories (OSEL) are investigating how the technology may affect manufacturing of medical devices of the future.

FDA is paying increased focus on AM in regulatory science that involves developing new tools, standards and approaches to evaluate FDA regulate products.

At the FDA’s Functional Performance and Device Use Laboratory, computer-modeling methods have been developed and adapted to determine the effect of design changes on the safety and performance of devices when used in different patient populations.

In an era of increasingly personalized solutions tailored to an individual patient or a group that shares certain characteristics, including anatomical features, additive manufacturing helps fine-tune the patient-fitted products.

At the FDA’s Laboratory for Solid Mechanics, investigation is underway to ascertain how different printing techniques and processes affect the strength and durability of materials used in medical devices. This study will help develop standards and set parameters for scale, materials, and other critical aspects that contribute to product safety and innovation.

Partnering with a Vendor: Overcoming Challenges in Personalizing Knee Systems through Additive Manufacturing Medical device manufacturers face challenges in launching their products globally due to challenges in managing the supply chain as well as understanding the needs of patients in markets with limited manufacturer presence.

Manufacturers can overcome these challenges by partnering with a reliable vendor.

Engineering service providers with expertise in medical devices and additive manufacturing can provide the requisite services, solutions and capabilities. This will enable avoiding risks associated with personalized knee systems

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and additive manufacturing while exploring their potential to the maximum. A few key areas in which vendors can play a role in the additive manufacturing of personalized knee systems include: • Design and development Specialized vendors with superior capabilities in design and development of orthopedic implants and instruments can provide experienced concurrent engineers to execute design transfer to manufacturers and ensure quality of end products. By collaborating with third parties, medical device manufacturers can leverage a whole gamut of services and solutions for personalized knee systems.

Many specialize in design software that helps manufacture high quality, precise and madeto-fit knee systems to enhance customer satisfaction. Third party firms also provide support for adopting industry standards in processes, along with leading-edge design and data formats.

• Supply chain management By leveraging their robust supplier network and efficient supplier management processes, vendors can help manufacture at competitive prices. These vendors, with their experience of working with multiple medical device manufacturers based across the globe, can assist in reducing cultural gaps and can help manage the supply chain with their global presence.

• Market needs Medical device manufacturers can utilize vendors’ experience of working with hospitals, surgeons, and clinical laboratories to understand the voice of the customer through market surveys.

References Research Article by BioMed Central on:

1.

Custom-designed orthopedic implants evaluated using finite element analysis of patient-specific computed tomography data: femoral-component case study

http://www.ncbi.nlm.nih.gov/pmc/articles/ PMC2100040/ Emerging technology evidence report “Total Knee Replacement Using Patientspecific Templates” © 2012 ECRI Institute.

2.

https://www.ecri.org/Documents/Sample_ Reports/Emerging_Technology_Report.pdf Summary of a roundtable forum “Additive manufacturing: Opportunities and Constraints” held on 23 May 2013 hosted by the Royal Academy of Engineering

3.

http://www.raeng.org.uk/news/ publications/list/reports/Additive_ Manufacturing.pdf Report by IDA Science and Technology Policy Institute on “Additive Manufacturing: Status and Opportunities (March 2012)”.

4.

http://www.metal-am.com/ articles/002731.html

5.

RBC Capital Markets report on “3D Printing: From Prototyping Evolution to Manufacturing Revolution”

6.

Blog by FDA Voice - “FDA Goes 3-D” posted on August 15, 2013 by Steven K. Pollack, Ph.D. and James Coburn, M.S.

7.

Steven K. Pollack, Ph.D. is Director of FDA’s Office of Science and Engineering Laboratories (OSEL) at FDA’s Center for Devices and Radiological Health. James Coburn, M.S. is a Research Engineer in OSEL.

http://blogs.fda.gov/fdavoice/index.php/ tag/national-additive-manufacturinginnovation-institute/

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Authors Kuldeep is head of medical business unit at Cyient and is responsible for global operation of the medical technology group. Kuldeep is based out of Bangalore, India.

Kuldeep’s primary focus is global strategy and business development. He is well experienced in product development, system value engineering, and innovative technology development projects in the medical industry.

He has expertise in various medical segments, including: • Medical devices: Orthopedic, cardiovascular, spine and trauma • Medical equipment: Diagnostic imaging (MRI, X-Ray, ultrasound and CT), ultra low temperature freezers, In-vitro-diagnostics, patient monitoring, sterilization and endoscope re-processors Kuldeep studied at University of Allahabad and holds a Bachelor’s degree in Mechanical Engineering.

Ankur, a program manager in medical business unit is responsible for managing pre-sales and program management for medical device customers. Ankur is based out of New Delhi, India.

He is senior level GDTP certified by ASME and a certified value engineer. Ankur has experience in the areas of product design and development and system value engineering.

He has delivered various projects into the therapeutic areas including spine and orthopedics, cardiology and diagnostics.

Ankur studied at Institute of Technology and Management, Gurgaon, India and holds a Bachelor’s degree in Mechanical Engineering.

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Updated June 2016

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