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The need for continuous improvement in product quality, reliability, and safety arises due to recalls, updates of Regulatory requirements, and the desire to gain a competitive advantage. The newly introduced changes may alter the risk profile of the device, and the device manufacturers must revisit risk evaluations that pinpoint and reduce part or system failures over the product's lifecycle.
One of the widely used risk analysis methods is Failure Modes and Effects Analysis (FMEA) which follows the IEC 60812:2018 standard. The FMEA methodology offers a systematic and disciplined approach for assessing all potential failure modes for a product by applying it throughout its many lifecycle phases.
The FMEA tool can evaluate the device design (DFMEA) or the device manufacturing process (PFMEA). The current article elaborates on DFMEA and its most common failure modes, focusing principally on the device, including device features, properties, components, and raw materials used.
Objectives of DFMEA
- Focus on failure modes brought on by faulty design
- Optimize costs while maximizing design quality, reliability, and maintainability
- Identify, remove, or reduce potential hazards to the product and user to an acceptable level
- Identify the product's crucial and essential features
- Assess the probable effects of failure on the product or user before allocating engineering resources and efforts
- Establish a link between manufacturing, quality, service efforts, and design engineering efforts
DFMEA Across Various Phases of Medical Device Life Cycle
Several concepts are developed at the start of the design phase based on the product design target specifications defined in the feasibility phase. DFMEA helps in choosing the most promising concept as a means of locating respective flaws. At this point, there is frequently little information available, but design analysis or product recalls of items with a comparable design can help identify the failure modes. Comparing similar devices and their histories from the medical device reports may be done when assessing the likelihood of danger.
During the development phase, before building the prototype, a more detailed DFMEA can be performed to minimize design defects, obliterate high-severity hazards, and reduce as many medium- and low-severity hazards as possible. As there is substantial flexibility at this early design stage, the cost of major changes to make the device safer would be minimal.
What are the Most Common Failure Modes?
Like any engineered device, medical devices sometimes cease to perform the intended function. It may happen due to purely biological, biomechanical, or service conditions that exceed their intended design limits. Some examples of common failure modes are as below:
Overload- Overload occurs when a part is subjected to a single, monotonic load that exceeds its strength. It can cause significant deformation and fracture of a device. Overloads occur more commonly in surgical tools than in implants. Overload fracture can be generally divided into two types: ductile and brittle. It is often caused due to the use of improper materials.
Fatigue-Fatigue is the accumulation of repeated loading-induced damage that results in the initiation and propagation of cracks. Fatigue is known to cause 80% of all engineering failures in general. It holds mainly in the hip, knee, and vascular implants.
Corrosion-The human body presents an aggressive chemical environment for implants. Moreover, sterilization and cleaning environments potentially contribute to corrosion-induced failures in surgical tools.
Fretting- Fretting is a corrosion-assisted wear process between two metal surfaces that results in surface damage and increased susceptibility to fatigue crack initiation. Fretting is commonly seen in orthopedic and vascular implants, particularly when stents overlap.
It stands to reason that utmost care and meticulous engineering methods need to be employed in the design of medical devices because they play an essential role in health care as they help increase the longevity of consumer lives.
However, FMEA is a review tool to enhance product reliability. To meet the risk management expectations of EU MDR, US FDA, and other Regulatory authorities, medical device manufacturers need to fulfill ISO 14971: 2019 requirements as it provides a more comprehensive approach.
For more insights on FMEA and medical device risk consulting, connect to our Regulatory experts today!
