Significance and Use
4.1 This document provides guidance for a range of assessments and evaluations to aid in preclinical research and device development of hard-on-hard total hip replacement and hip resurfacing devices used for the repair of musculoskeletal disorders.
4.2 The user is encouraged to use appropriate ASTM International or ISO standards to conduct the physical, chemical, mechanical, biocompatibility, and preclinical tests on alloy fabricated forms, ceramic material samples, device components, or devices before assessment in an in vitro model.
4.3 Studies to support regulatory submissions should conform to appropriate regulatory requirements and guidelines for the development of medical devices.
4.4 Assessments with physical, chemical, mechanical, biocompatibility, and preclinical tests on hard-on-hard hip prosthesis components are not necessarily predictive of human results and therefore should be interpreted cautiously with respect to potential applicability to clinical conditions. Referenced metal-onmetal or ceramic-on-ceramic hip prosthesis publications can be found in the Bibliography section at the end of this guide for further review.
1.1 This guide covers materials and design recommendations and general test methods for the chemical, mechanical, and preclinical assessment of implantable devices with hard-on-hard articulations intended to replace a hip joint. The provided guidance is intended to encompass both Total Hip Replacement (THR) devices with stems that extend or fix within the intramedullary canal as well as Hip Resurfacing Arthroplasty (HRA) wherein only the hip articulating surfaces are replaced. There has been long term clinical experience with metal-on-metal articulating components manufactured from cobalt-28 % chromium-6 % molybdenum (Co28Cr6Mo) alloy (Specifications , , or ) or high purity alumina (ISO 6474-1) and ceramic-on-ceramic articulating components manufactured from high purity alumina (ISO 6474-1) or alumina matrix composite ceramics (ISO 6474-2). There has also been some limited clinical experience with metal (Co28Cr6Mo) on alumina matrix composite ceramic articulating components. This guide has been created based on the current understanding derived from those clinical histories. Device articulating components manufactured from other metallic alloys, ceramics or with coated or elementally modified articulating surfaces could also be evaluated with this guide. However, such materials that do not have a history of clinical use may present different risks.
1.2 This guide applies to the acetabular and femoral articulating components of hard-on-hard hip replacement devices. Acetabular components can be monoblock, or a modular component with a separate acetabular shell and acetabular liner. As stated above, articulating components have been made from Co28Cr6Mo for a metal-on-metal bearing; high purity alumina or alumina matrix composite ceramics for a ceramic-on-ceramic bearing; and Co28Cr6Mo and alumina matrix composite (ISO 6474-2) for a metal-on-ceramic bearing. Modular acetabular shells have to date been made from Ti-6Al-4V or Co28Cr6Mo. The shell is considered part of the acetabular component. Acetabular components may have external coating and/or porous structure intended for uncemented, press-fit or biological fixation; or, for use with bone cement.
1.3 This standard is a summary of available specifications, test methods, practices, and guides from published standards or the scientific literature. Their clinical relevance is unproven. Most of the methods do not have an established precision and bias; therefore, their repeatability and reproducibility has not been established. As the clinical relevance of these methods have not been established, consequently, most do not have performance requirements. This document does not require that all the listed methodologies are always necessary to evaluate these implant systems provided justification for not using each unused method is provided. This document does not intend to prevent the use of new methodologies as they are developed.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health and environmental practices and determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.