One requirement of a biomedical implant material is that it must be capable of being sterilized. Since many implant materials are flowable, they must be housed in a container. However, sterilizing the flowable implant material independently from the container, and then aseptically assembling the two units increases the risk of contamination and bioburden. Therefore, sterilization efforts have focused upon sterilizing the flowable implant material while it is housed in the container.
However, it is often the case that such prefilled containers can not be sterilized by traditional approaches (such as irradiation or heat) because the biomedical implant material contained within the container does not remain in a stable condition when undergoing these processes.
As a result of these shortcomings, a gaseous disinfectant is often used in implant-container sterilization procedures. For example, in one such approach, a biomedical implant material is housed in a syringe, and gas is allowed to permeate the material through the two open ends of the syringe. However, due to the slow rate of gas permeation through the implant material, implant material sterilization using this approach can not be accomplished in a practical time frame.
It has been suggested that vents be applied at both ends of the syringe, as this approach has been successfully used to sterilize the internal surfaces of an empty syringe. However, when this approach was tried with a syringe having a curable silicone composition therein, complete sterilization of the composition was not achieved even after 18 hours with high sterilent gas concentrations.
Deep vacuum processes have also been considered to facilitate delivery of sterilent gas into empty syringes. However, such processes offer no advantage when attempting to sterilize a filled syringe.
U.S. Pat. No. 5,997,544 (Nies) discloses a process for making bone cement, utilizing a sterile filter to allow gas entry and release.
U.S. Pat. No. 5,989,852 (Hendricks) discloses the insertion and positioning of a compressible insert to regulate the amount of gas entering a chamber as a test indicator of the amount of sterilant penetration. It does not disclose the use of an insert that protrudes into the material, nor a cartridge insert providing sterilant penetration.
U.S. Pat. No. 5,870,855 (Biddle) discloses the insertion and positioning of a gas-transmissive plug positioned to regulate the amount of gas entering a chamber as a test indicator of the amount of sterilant penetration. It does not disclose the use of an insert that protrudes into the material, nor a cartridge insert providing for sterilant penetration.