【国外标准】 Standard Specification and Test Methods for Absorbable Plates and Screws for Internal Fixation Implants

4.1 Absorbable devices are intended to degrade and absorb over time once they are implanted into the body. This makes a removal operation unnecessary, which is especially advantageous for pediatric patients.4.2 While the polymer degrades due to hydrolytic reaction with the environment, the mechanical performance of the device also deteriorates. The key to developing mechanically effective fracture fixation systems based on absorbable devices is to provide an adequate level of fixation strength and stiffness for a time frame that exceeds that expected for fracture healing. Once the fracture is healed, the device can be completely absorbed by the body. The biological performance of the device, particularly for application at a bony site, may be enhanced by incorporation of bioactive fillers in the polymer.4.3 Absorbable devices will be tested using test methods that are similar to those used to evaluate conventional metallic devices. The pre-test conditioning requirements, handling requirements, and time-dependent mechanical property evaluations for absorbable devices shall be considered.4.4 This specification and accompanying test methods are intended to complement the more general considerations for the assessment of absorbable polymeric implants that are described within Guide F2902.FIG. 1 Screw Parameters1.1 This specification and test methods cover the mechanical characterization of plates and screws for orthopedic internal fixation. Covered devices are fabricated from one or more hydrolytically degradable polymer (from this point on referred to as “absorbable”) resins or resin composites.1.2 This specification establishes a common terminology to describe the size and other physical characteristics of absorbable implants and performance definitions related to the performance of absorbable devices.1.3 This specification establishes standard test methods to consistently measure performance-related mechanical characteristics of absorbable devices when tested under defined conditions of pretreatment, temperature, humidity, and testing machine speed.1.4 This specification may not be appropriate for all absorbable devices, especially those that possess limited hydrolytic susceptibility and degrade in vivo primarily through enzymatic action. The user is cautioned to consider the appropriateness of the standard in view of the particular absorbable device and its potential application.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 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.1.7 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.