Medical Metrology Assists with FDA Reporting Rules
Medical device manufacturers have unique and heavy reporting requirements. Providers of metrology equipment and inspection software are making strides towards helping them respond.
By Bruce Morey
As in the aerospace and automotive industries, medical device manufacturers must collect quality and metrology data and store it for future reference. But the reporting requirements are much heavier in the medical arena, as Dave Criss, CQE, an assistant program manager for Mitutoyo Corporation (Aurora, IL) told ME Media in a recent interview.
“Compared to other industries, medical device manufacturers who work with the FDA have the most stringent requirements, especially in terms of data security and retention,” Criss said. For example, “they also must log who collected and stored the data using an electronic signature.”
Since FDA requirements tend to be the most stringent, Mitutoyo used them—particularly Code of Federal Regulations (CFR) Title 21—to establish the design targets for its Measurlink software package, which collects, stores and manages metrology and quality data.
Mitutoyo offers Measurlink as a scalable solution, tying suppliers, customers, and corporate users into a single system, including SPC analysis and charts. It is not just for CMMs or other high-end metrology devices—it also processes data from digital gaging, multigage fixtures, surface and roundness testing, as well as from devices equipped with wireless data transfer. “Measurlink can also bring in data from competitive equipment, such Starrett or Brown & Sharpe, among many others,” Criss said. Importantly for medical, Measurlink provides user authentication and password protection to ensure that individual users are tracked and logged.
Another important control discipline in medical device manufacturing is tightly maintaining version control of the measuring programs used to drive CMMs and other automated metrology devices, according to Josh Smokovitz, product manager for Carl Zeiss Industrial Metrology (Maple Grove, MN). While important in other industries such as aerospace, he stressed it is especially important in medical device manufacturing to satisfy FDA reporting requirements. The FDA requires that the parts programs themselves be approved. Once approved they cannot be revised. “Once you have a parts program,” Smokovitz said, “the question becomes how do you keep that controlled? How do you control and keep track of revisions to the program, as well as the data the programs generate?”
In larger organizations, it is easy for different programmers to tweak the program and get out-of-sync with other copies in other locations. “If even one programmer in one of those facilities decides they need to change the tolerances to the program in response to, say, a print change, a number of issues arises,” Smokovitz said. “Was he correct in making those changes? What happens to the parts at the other facilities?”
Other issues such as measurement strategies, selection of critical characteristics or features, or tolerance classes all must remain uniform and configured. Zeiss has an answer to this problem with their Master Control Center, or MCC, software. “It supplies one master copy of parts programs, tightly controlled from a central server, with only password access,” Smokovitz said.
In addition, MCC also has modules for onboard diagnostics, machine data logging, and a paperless record archive. The paperless record archive—which configures any documents in any format—can be attached to any one of the parts programs configured in the MCC. These could explain what the measuring program does. Other auxiliary data can also be attached. It also tracks who accesses measurement results with a time stamp, and provides a searchable database. “This is especially important if you are measuring upwards of 500 or 1000 parts a week and want to find that data again,” Smokovitz said. The database is real-time and connects reports to barcode systems used to track individual parts or lots.
How big a network can MCC control? “We currently have a customer in New York who has six or seven different labs across the US running 30 Zeiss machines, and he can tell instantaneously what program they’re running, how much time is left to completion of each [measurement] program, and if there is any error on that machine,” Smokovitz said.
Small Companies, Big Problems
While large companies with multiple machines and facilities have unique problems of maintaining versions and control, small and medium-sized companies have additional problems, especially at the beginning of production for a particular part. There are three phases of qualifications that medical device manufacturers must perform to prove their process is valid to the FDA, according to Nate Rose, Applications Engineering Manager for Optical Gaging Products (OGP; Rochester, NY).
Installation Qualification (IQ) is the first phase, Operational Qualification (OQ) is the second, and Performance Qualification (PQ) is the third and final phase. IQ verifies the system is installed and calibrated according to the manufacturer’s specifications. IQ also includes verification of the environment in which the equipment is installed, and other factors such as documentation, traceability, utilities, and contact materials.
Operational Qualification (OQ) is a procedure to verify that a metrology device operates as intended and is effective and reproducible. The OQ tests include standard operating conditions, verification of accuracy and repeatability (using NIST traceable standards other than those used for calibration) for all axes and sensors. OQ also verifies other aspects of the FDA requirements, including access control and tracking, data management and archiving, preventative maintenance schedules and other factors. “The results of an OQ are documented and maintained as a permanent record of the system’s performance.” Rose said.
The final phase, PQ, for measurement systems, typically includes verification of gage repeatability and reproducibility using typical sample parts and their respective measurement fixtures, routines and procedures.
Although OGP is primarily a supplier of metrology equipment and software, it developed its validation services to help small and medium-sized enterprises through their IQ, OQ, and PQ phases. “Our customers asked us to provide what we call the FDA Service, because many companies do not have the staff or artifacts to conduct the IQ and OQ on their own,” he said. For its FDA Service, OGP created procedures and specialized NIST traceable artifacts designed to verify the equipment, sensors and software they offer. These might be chrome-on-glass line scale artifacts, or specialized gages for verifying specific geometric construction capabilities in the software. The resulting test procedures verify the system meets the intended requirements. “It’s effective for them because they do not need to purchase the artifacts or re-develop detailed procedures and documentation,” Rose said.
OGP developed a package of validation routines using its SmartFeature software. OGP specifically designed it for multisensor metrology programming and support. “We really could not provide the FDA Service without SmartFeature software. It provides the user access control, logging, audit, and editing control of the measurement routines that FDA requires,” Rose said. “We need to log who inspected something, when, and track any modification of the inspection routines.”
At a more fundamental level, medical device manufacturers also need to control and evaluate machine tool performance to meet certain requirements of CFR Title 21, according to Clive Warren of Renishaw (Hoffman Estates, IL). “If a device manufacturer is machining parts, they are expected to know the capabilities of their machines prior to producing those parts,” he said. “The theory is they should not be producing any defective parts—even if they end up inspecting them 100% anyway.” Renishaw offers their QC20W device for ballbar analysis as a key tool for determining machining capability. The QC-20W measures to the standardized circularity test as defined in international standards such as ISO 230-4.
“As an approved methodology for determining the contouring performance of machine tools, it helps meet the reporting requirements for CFR Title 21,” he said. This is critical on complex parts such as knee or hip replacements, with complex curved and contoured surfaces, according to Warren. “You need to know how all the different interrelated machine functions are performing and what their effect may be on workpiece quality. Also, since the QC-20W ballbar test report meets the requirements of ISO 230-4, it can be accepted as part of the reporting requirement in the FDA regulations,” Warren said.
New Sensors and Verifications
Even when developing a new sensor, the data requirements for the FDA are important considerations. Such is the case with Hexagon Metrology (North Kingstown, RI) and a pilot project they are pursuing using Micro-Focal Computed Aided Tomography (Micro-CT). This Micro-CT device measures parts in a working cylinder of space about 140-mm tall and about 200 mm in diameter, about the size of a small can of soda, according to Steve Darrouzet, applications manager for Micro CT. The nominal scan resolution is about 5 µm to capture the whole field-of-view, though the device can scan down to 0.5 µm (by giving up field-of-view).
“It is targeted initially for an implantable cardiac device,” Darrouzet said. Because of this focus, early in their development they knew that calibration routines would be vital in making the device useful to their target market. They made these similar to the international standards for touch probe CMMs, ISO 10360, but adapted for the unique aspects of a CAT scan sensor. “What FDA regulators are looking for is that the equipment is calibrated to known standards,” Darrouzet said.
He pointed out that while rigorous, the FDA gives much flexibility to the manufacturers themselves. What to measure depends on the risks of the part. The variability in medical devices is so vast—from stents, to orthopedic implants, to tongue depressors—flexible regulations are a necessity. An inspection might be quite simple for a set of tongue depressors or drug containers compared to a cardiac drug-eluting stent.
“Simple devices with a low impact on the patient might use simple statistical measures reporting on lots, whereas a cardiac device will be 100% inspected, over many critical features, and tracked by serial number,” he said. Even then, the lot of tongue depressors must be as traceable as an individual cardiac stent.
Hexagon Metrology also offers services to jump-start companies. While some routines in their software, such as PC-DMIS or PC-DMIS Reshaper, are broadly applicable, special-purpose ones are needed for the unique needs of each customer and their parts. “We build in traceability and other requirements that meet the CFR Title 21 needs for our clients. They do not have to simply buy a piece of equipment and then do it on their own—we can help them,” Darrouzet said.
First Article Inspection, Many Times
The variability of the human body is a unique aspect of manufacturing some implants. David Olson of Verisurf (Anaheim, CA) explained the high-tech way of manufacturing prosthetics is to scan the human side of the device and ‘reverse engineer’ it, creating a 3D CAD model to produce a perfect fit.
The Verisurf software package is designed to convert data—especially point clouds from metrology devices—into CAD for reverse engineering or ‘as built’ applications. Olson also believes that creating accurate profiles from point cloud data is a special strength of the Verisurf package, especially creating profiles.
While the concept of First Article Inspection is certainly not unique to medical devices, manufacturing such one-off orthopedic implants takes it to the extreme. In cases requiring perfect match, every prosthetic could be considered a First Article. Olson cites the international ISO 13485 for quality management of medical devices as a critical requirement for First Article Inspection. “A company would cite the requirements of ISO 13485 for First Article Inspection and inform the FDA that is what they are doing,” he said, to meet CFR Title 21.
Of course, not all medical devices are so unique, and in those cases, Olson is quick to point out that the First Article inspection plan developed in Verisurf can be adapted as a production inspection plans as well. Verisurf also contains SPC routines for evaluating production lots that do not require 100% inspection.
While all this is technically challenging, Olson finds one of the bigger challenges is more personal. “The biomedical industry of necessity is very conservative. You are dealing with the human body, human lives, and legal liability,” he said. “Industry professionals are just starting to get comfortable with 3D models and inspections based on 3D CAD. Quality professionals are used to looking at 2D drawings—we have to prove to them that 3D CAD models are better.”
Measuring is a System Process
Criss from Mitutoyo also points out an important aspect of measurement data and quality—software and measuring devices are only part of a quality system. “Sometimes a new customer will ask if our software is FDA compliant,” Criss said. He can point out their Measurlink software has all the functions a system designed to satisfy FDA reporting requirements needs. But, he added, “To be truly FDA compliant, it is all about the process that the customer employs, how they use our software within that process to ensure that they’re adhering to FDA standards.” ME
This article was first published in the May 2013 edition of Manufacturing Engineering magazine. Click here for PDF.