麻省理工大学：《Design of Medical?Device》chapter 5 Replacing Organs with Permanent Prostheses

CHAPTER 5 Replacing Organs with Permanent Prostheses 5.1 Defining the clinical problem 5.2 Anatomical Considerations 5.3 Biomechanical considerations 5.4 Functional Requirements 5.5 Goodness of fit 5.6 Fixation

CHAPTER 5 Replacing Organs with Permanent Prostheses 5.1 Defining the Clinical Problem 5.2 Anatomical Considerations 5.3 Biomechanical Considerations 5.4 Functional Requirements 5.5 Goodness of Fit 5.6 Fixation

5.1 ABSORBABLE VERSUS PERMANENT DEVICES/IMPLANTS Absorbable Permanent Regeneration Replacement of function Temporary or permanent (prosthesis"-"artificial organ") Function Template for regeneration Replicate/approximate key Temporary replacement of function(s )of the organ key function(s)until regeneration occurs Materials Absorbable resorbable Metals, nondegradable polymers, biodegradable"polymers (synthetic or natural)and certain calcium compounds Incorporation of Tissue engineering Hybrid artificial organs Cells Requirem Potential for tissue regeneratio Benefit/risk ration for Use 1)ability of cells to divide or regenerate organelles 2) Integration into the organ system

5.1 ABSORBABLE VERSUS PERMANENT DEVICES/IMPLANTS Absorbable Goal Regeneration Function Template for regeneration. Temporary replacement of key function(s) until regeneration occurs Materials "Absorbable, resorbable, biodegradable" polymers (synthetic or natural) and certain calcium compounds Incorporation of "Tissue engineering" Cells Permanent Replacement of Function: Temporary or permanent ("prosthesis" - "artificial organ") Replicate/approximate key function(s) of the organ Metals, nondegradable polymers, and ceramics Hybrid artificial organs Requirements Potential for tissue regeneration: Benefit/risk ration regenerate organelles for Use 1) ability of cells to divide or 2) Integration into the organ system

Limitations Limitations in regeneration erfect ada to changing 1)size of defect, demands of human activity 2)number of tissues involved 3)controlling mechanical and chemical environment during Implications in Incomplete regeneration of Inability to adequately duplicate Falling Short of reparative tissue function(need for revision with Goal (accelerated degeneration) additional loss of tissue Adverse Effects of Premature degradation Fracture. wear. and corrosion the body on the (polymer degradation) Implant(chemical and mechanical Adverse effects Local response Same of the Implant on degradation products cause the bod cell toxicity or inflammation, ("Biocompatibility ) or alteration in strain distribution S ystemic response 1)migration of material to distant organs with effects 2)immune response Complications Bacterial infection Infection (lower incidence than with permanent devices implant surface

Limitations Limitations in regeneration 1) size of defect, 2) number of tissues involved, 3) controlling mechanical and chemical environment during regeneration. Implications in Incomplete regeneration of Falling Short of reparative tissue Goal (accelerated degeneration) Adverse Effects of Premature degradation the Body on the Implant (chemical and mechanical environment) Adverse Effects Local response: of the Implant on degradation products cause the Body cell toxicity or inflammation, ("Biocompatibility") or alteration in strain distribution Systemic response: 1) migration of material to distant organs with effects, 2) immune response Complications Bacterial infection (lower incidence than with permanent devices) Imperfect adaptation to changing demands of human activity. Inability to adequately duplicate function (need for revision with additional loss of tissue) Fracture, wear, and corrosion (polymer degradation) Same Infection: bacteria colonize implant surface