Biomedical Engineering Theory And Practice/Requirements of Biomaterials

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Requirements for Biomaterials[edit]

Mechanical requirements[edit]

Table 3. Biological Tissue:Mechanical Properties[1]

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 [2]

Biocompatibility[edit]

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?[3]

Initial Consideration from ISO- 10993, "Biological Evaluation of Medical Devices Part 1: Evaluation and Testing"[4]

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ISO 10993-8:2001 Biological evaluation of medical devices Part 8: Selection of reference materials (withdrawn)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

Healing[edit]

Industrial involvement[edit]

the extensive industry-FDA interactions that occur during product development

Ethics[edit]

TABLE 5. Ethical Concerns Relevant to Biomaterials Science[5]

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?

Regulations[edit]

  1. Black J, Hastings GW. Handbook of Biomaterials Properties. London, UK: Chapman and Hall, 1998
  2. Invalid <ref> tag; no text was provided for refs named mechanicalproperties2
  3. >"Medical Device Biocompatibility". http://clinicaldevice.typepad.com/cdg_whitepapers/biological-safety/. Retrieved 31 May 2011. 
  4. "Use of International Standard ISO-10993, 'Biological Evaluation of Medical Devices Part 1: Evaluation and Testing' (Replaces #G87-1 #8294) (blue book memo)". FDA. http://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/GuidanceDocuments/ucm080735.htm. Retrieved 12 December 2014. 
  5. Invalid <ref> tag; no text was provided for refs named biomaterials