Article by Tony Newson, AvestaPolarit (This article first appeared in Business Briefing: Medical Device Manufacturing & Technology 2002, published by World Markets Research Centre, London www.wmrc.com). The application of austenitic, martensitic and precipitation hardening stainless steel types in medical implant and dental and surgical instruments is discussed. The special implant grades to ISO 5832 are compared to more commonly recognisable ISO 7153-1 instrument grades, used where body contact is only transient. A comparison of electropolished and mechanically polished finishes for stainless steel medical devices is made. The reusability and recycling issues are discussed in relation to single use instruments where the spread of infection is a possible risk.
Stainless steels for surgical implants are specified in ISO 5832. Part 1 (1997) covers two steel types, compositions D and E. Part 9 (1992) covers a single high nitrogen grade.
Stainless steels for surgical instruments are specified in BSENISO 7153-1:2001, which incorporates BS 5194-1:1991. This edition renumbered the previous ISO 7153-1:1991 as the BSENISO 7153-1:2001. This covers metallic materials for surgical instruments, part one covering only stainless steels.
Concerns about the potential for the nickel content of stainless steels to result in health risks have been extensively investigated and reported. The Euroinox publication 'Stainless Steel-The Safe Choice' summarizes the issues and findings.