Biomedical Engineering Theory And Practice/Requirements of Biomaterials

Requirements for Biomaterials

Mechanical requirements

Table 3. Biological Tissue:Mechanical Properties

Hard Tissue
Tissue	Modulus(GPa)	Tensile Strength(MPa)	Strain at Break(%)
Cortical bone(longitudinal direction)	17.7	133	1-3
Cortical bone(transverse direction)	12.8	52	1-3
Cancellous bone	0.4	7.4	5-7
Enamel	84.3	10
Dentine	11.0	39.3
Soft Tissue
Tissue	Modulus(MPa)	Tensile Strength(MPa)	Strain at Break(%)
Articular cartilage	10.5	27.5	15-20
Fibrocartilage	159.1	10.4	15-20
Smoothe muscle,relaxed	0.006	-	300
Smooothe muscle,contracted	0.01	-	300
Carotid artery	0.084±0.22	-	-
Cerebral artery	15.69	4.34	50
Cerebral vein	6.85	2.82	83
Pericardium	20.4±1.9	-	34.9±1.1
Patellar Tendon	660±266	64.7±15	14±6
skin	0.1-0.2	7.6	-
intraocular lens	5.6	2.3	-

Table 2.How to measure mechanical properties of engineering biomaterials

Biocompatibility

According to Nancy J. Stark, there are commonly three stories in which manufacturers call on CDG for biocompatibility: a) FDA has brought up questions about the safety tests you performed, b) you can decide whether you need sensitization, genotoxicity, or carcinogenicity tests, or not, c) you have a new device and don't have a clue as to what tests to do. Can an expert opinion help?

Initial Consideration from ISO- 10993, "Biological Evaluation of Medical Devices Part 1: Evaluation and Testing"

Table .List of the standards in the 10993 series for biocompatibility evaluation

ISO	Details
ISO 10993-1:2009	Biological evaluation of medical devices Part 1: Evaluation and testing in the risk management process
ISO 10993-2:2006	Biological evaluation of medical devices Part 2: Animal welfare requirements
ISO 10993-3:2014	Biological evaluation of medical devices Part 3: Tests for genotoxicity, carcinogenicity and reproductive toxicity
ISO 10993-4:2002/Amd 1:2006	Biological evaluation of medical devices Part 4: Selection of tests for interactions with blood
ISO 10993-5:2009	Biological evaluation of medical devices Part 5: Tests for in vitro cytotoxicity
ISO 10993-6:2007	Biological evaluation of medical devices Part 6: Tests for local effects after implantation
ISO 10993-7:2008	Biological evaluation of medical devices Part 7: Ethylene oxide sterilization residuals
ISO 10993-8:2001	Biological evaluation of medical devices Part 8: Selection of reference materials (withdrawn)
ISO 10993-9:1999	Biological evaluation of medical devices Part 9: Framework for identification and quantification of potential degradation products
ISO 10993-10:2010	Biological evaluation of medical devices Part 10: Tests for irritation and delayed-type hypersensitivity
ISO 10993-11:2006	Biological evaluation of medical devices Part 11: Tests for systemic toxicity
ISO 10993-12:2012	Biological evaluation of medical devices Part 12: Sample preparation and reference materials (available in English only)
ISO 10993-13:1998	Biological evaluation of medical devices Part 13: Identification and quantification of degradation products from polymeric medical devices
ISO 10993-14:2001	Biological evaluation of medical devices Part 14: Identification and quantification of degradation products from ceramics
ISO 10993-15:2000	Biological evaluation of medical devices Part 15: Identification and quantification of degradation products from metals and alloys
ISO 10993-16:1997	Biological evaluation of medical devices Part 16: Toxicokinetic study design for degradation products and leachables
ISO 10993-17:2002	Biological evaluation of medical devices Part 17: Establishment of allowable limits for leachable substances
ISO 10993-18:2005	Biological evaluation of medical devices Part 18: Chemical characterization of materials
ISO/TS 10993-19:2006	Biological evaluation of medical devices Part 19: Physico-chemical, morphological and topographical characterization of materials

Industrial involvement

the extensive industry-FDA interactions that occur during product development

Ethics

TABLE 5. Ethical Concerns Relevant to Biomaterials Science

Is the use of animals justified? Specifically, is the experiment well designed and important so that the data obtained will justify the suffering and sacrifice of the life of a living creature?

How should research using humans be conducted to minimize risk to the patient and offer a reasonable risk-to-benefit ratio? How can we best ensure informed consent?

Companies fund much biomaterials research and own proprietary biomaterials. How can the needs of the patient be best balanced with the financial goals of a company? Consider that someone must manufacture devices—these would not be available if a company did not choose to manufacture them.

Since researchers often stand to benefit financially from a successful biomedical device and sometimes even have devices named after them, how can investigator bias be minimized in biomaterials research?

For life-sustaining devices, what is the trade-off between sustaining life and the quality of life with the device for the patient? Should the patient be permitted to “pull the plug” if the quality of life is not satisfactory?

With so many unanswered questions about the basic science of biomaterials, do government regulatory agencies have sufficient information to define adequate tests for materials and devices and to properly regulate biomaterials?

Should the government or other “third-party payors” of medical costs pay for the health care of patients receiving devices that have not yet been formally approved for general use by the FDA and other regulatory bodies?

Should the CEO of a successful multimillion dollar company that is the sole manufacturer a polymer material (that is a minor but crucial component of the sewing ring of nearly all heart valves) yield to the stockholders’ demands that he/she terminate the sale of this material because of litigation concerning one model of heart valve with a large cohort of failures? The company sells 32 pounds of this material annually, yielding revenue of approximately $40,000?

Should an orthopedic appliance company manufacture two models of hip joint prostheses: one with an expected “lifetime” of 20 years (for young, active recipients) and another that costs one-fourth as much with an expected lifetime of 7 years (for elderly individuals), with the goal of saving resources so that more individuals can receive the appropriate care?