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Pareto Analysis: Tools for New Product Testing

Testing is, of course, a critical component to product development. To better understand how it can be proactively employed to help ensure product quality and longevity, we reached out to John McCloy, Founder & President of Engineered Assurance and author of the article on the industry’s 1% failure rate that was published in the March issue. Our conversation evolved into discussion surrounding ways that testing and Pareto Analysis are being used in early upstream stages of product development.

Mr. McCloy stressed that when it comes to analyzing the problems uncovered in your test data don’t confuse the elements of frequency and importance. A poignant example he pointed out during our conversation is that for years, the focus on metal-on-metal hip implants was the common problem of stem breaks and screw fractures on the acetabular cup. Implant wear later became the culprit for massive recalls.

We thought you would find our conversation useful. Mr. McCloy’s insight on the topic follows.

BONEZONE: First, what role does testing play in new product development?

McCloy: Like all industries, the idea is to accelerate product development while improving quality. For some time now, testing has provided the real world baseline data needed for simulation. As new implants and devices are designed, computer-aided design (CAD) models are run through simulation software. This allows multiple design alternatives to be evaluated quickly, verified and validated as they are subjected to the stresses, strains and cycle data provided by testing. As a result, devices are developed at a fraction of the time and cost associated with building and testing multiple physical prototypes.

Like I said, this practice has been around for decades and is certainly not new. But as software tools, methodologies and best practices evolve, new product development will continue to look to testing to provide real-world baseline data.

BONEZONE: Where can one learn more about this in relationship to the orthopaedic industry?

McCloy: The American Society for Quality (ASQ) is an excellent resource. They provide many benefits and tools for the design, manufacture and testing of medical implants.


Frequency and importance don’t always go hand-in-hand. Remember, the most common problems aren’t always the most important problems.


BONEZONE: You mentioned verification and validation. We know from conversations with readers that confusion remains about V&V. Can you simply define the difference?

McCloy: While it’s true that the terms are often used interchangeably, verification and validation are complementary yet independent procedures. They are used together as a means to confirm that a product meets all intended requirements and specifications. Validation provides assurance that a product satisfies external or customer requirements, while verification is generally an internal process used to determine whether a product complies with a regulation, requirement, specification or other conditions. As your readers know, verification and validation are critical components of a quality management system—like ISO 9000. As such, it’s generally recommended that they be performed by a neutral third party.

BONEZONE: So, is implant failure information shared among the industry?

McCloy: Yes, to some extent. FDA publishes Manufacturer and User Facility Device Experience reports—MAUDE—that are freely available to all. These include internal recall and recovery of explant failures while providing insight into cause and frequency. When employed with a Pareto Analysis, weighted with severity, management can act quickly and decisively.

BONEZONE: How is Pareto Analysis used today?

McCloy: Pareto Analysis is based on the Pareto Principle—often referred to as the 80/20 rule. The idea is that for many events, roughly 80% of the effects come from 20% of the cause. I’m sure you’ve heard the expression that in business, 80% of sales come from 20% percent of customers.

Pareto Analysis is a decision-making process used for the selection of a limited number of tasks that produce significant overall effect. So in the business example, we would use Pareto Analysis to find the 20% of clients upon whom we should focus our time and energy.

With regard to medical implants or devices, we can say that 80% of the cost associated with defects will be attributed to 20% of those defects. In other words, some matter more. Instead of a knee-jerk reaction to something that happens frequently or trying to address everything, Pareto Analysis allows us to assign weights and prioritize based on importance. It allows manufacturers to identify and concentrate on fixing that 20% with the biggest consequences.

BONEZONE: Can you give an example?

McCloy: Each year, something like 320,000 people in the U.S. alone undergo hip reconstruction. With those numbers, the opportunity for failure and subsequent litigation costs are staggering. And when this in fact happened, most of the attention was focused on fixing the most common problems: stem breaks and screw fractures on the acetabular cup. This went on for years before massive recalls took place. As it turned out, metal-on-metal wear was the real culprit, and should have been the focus from the start. This issue was noticed two to three years ahead of the recall, but was not elevated as a top priority.