Biomedical Engineering Reference
In-Depth Information
3.2 Procedure
3.1 Introduction
The manufacture of joint replacement implants and instruments is a complex
process that is, in almost all countries, overseen by some official agency to
guarantee adherence to strict quality standards. In the United States manufacturers
must adhere to the FDA Good Manufacturing Practices (GMP) regulations [1] and
in the EU countries to an International Standard Organization protocol, such as
ISO 13485 and EU Directive MDD 93/42/EC [2, 3]. These manufacturing
standards are enforced by periodic inspections and enforcement actions where
needed.
The application and enforcement of these regulations is, however, a relatively
recent event, even though they have been in place for at least two decades. As a
result most of the earlier, and even some existing designs are not a product of a
formal, well controlled, design procedure. They, thus, often contain important
design defects.
Good design is the key to producing a quality product. The design process
should ensure that the design requirements (Design Input) are understood and
documented; the design should be continuously reviewed to ensure that the design
output matches the design input; and that the design is thoroughly verified and
validated before the design is released for production. The resulting final product
must meet the requirements for the design, meet all of the design specifications for
form and performance, and be introduced in a manner that is in compliance with
applicable regulations (Design Input). The device must also be validated after
initial production to insure that these requirements are met and will continue to be
met.
Good design, unfortunately, cannot be based entirely on adherence to
regulations. It must also be based on sound engineering methods and principles
and the applications of such methods and principles by talented, creative designers
with a high state of knowledge of the science and practice of orthopaedic implants
and instrumentation. Good design involves an understanding and input from
several disciplines such as Engineering, Manufacturing, QA, Medical Director,
Marketing, Sales and Regulatory Affairs.
3.2 Procedure
Product design is an iterative process that demands flexibility and the ability to
change the design, design inputs and design requirements. The procedure given
here is intended to provide a template for guiding the design process. As such,
different projects should have different requirements and all parts of this
procedure may not fit every project. This should be continually assessed during
the project using formal, documented, design reviews. All new designs or
significant changes to existing designs should be managed under such a procedure.
It should be noted that almost all design is actually redesign of some existing
product. Most design is design refinement or correction. Thus, the difference
between a “new” design and a design refinement is quite subjective. Generally a
