Week 8 - Implants Flashcards
What are the basic principles of medical implants
2 types of impants
Implants are placed inside or on body
STRUCTURAL:
1. To replace missing body parts
FUNCTIONAL
1. To deliver medication
2. Monitror body functions
3. Support organs and tissues
List 3 “Functional” Classifications of implants
- Orthopedic Implants
- joint replacements
- fracture fixation
- Opthalmic Implants
- intraocular lenses
- glaucoma drainage
- Cosmetic Implants
- breast
- facial
- rhinoplasty (nose)
List 3 “Purpose” Classifications of implants
- Bonestimulation Implants
- bone grafts
- dental implants
- Drug Delivery Implants
- hormonal implant
- insulin pumps
- pain management
- Neurostimulatory Implants
- vagus nerve stimulators
- deep brain stimulators
List the other classifications of implants
- Material
- metals (titanium, stainless steel)
- ceramics (hydroxyapatite)
- polymers (silicone, polyethylene)
- composites - Regulatory Approval (class)
- Class I = lowest risk
- Class II = moderate risk (requires some premarket data)
- Class III = highest risk (requires premarket testing + clinical trials) - Anatomy (part of body implated in)
- Release Mechanism
- Fixation Methods (is implant cemented, screwed to body etc.)
How do we manage patients with medical implants
Ensure pt awareness of…
- ADRs
- Education on how implant may interact with other drugs
- How to minimise risks
- Counsell on adminstration + potential SE
What are the ideal properties of an implant
- Sterile (or cant be placed in pt)
- Easy to insert
- Small in size (few µm to few cm)
- Biocompatible
- Stable in biological environments / physiological pH
- prevent degredation = therpeautic effect lost - Controlled and Sustained release
- from days to months / years - Good mechanical strength
What are the advantages of an implant
- ↑ compliance
- Convenience (don’t need to set doses)
- ↑ QoL
- Reduced SE
- bypass 1st pass metabolism
- conc. of drug remains stable - More targeted treatment
- Long lasting (sustained release)
- Dont have to remain in hospital like IV treatments etx.
What are the disadvantages of an implant
- Invasive
- Infection risk
- Difficult to remove
- ADR ~ immune response or allergic reaction
- Limited drug compatibility
- not all drugs can be delivered through implant - Implant failure
List the 2 common types of implant + examples
hint: relates to degradability
- Biodegredable
- Non-biodegradable
Describe how “Biodegradable” implant works
with examples
They degrade within the body (dont need to be removed via surgery)
EXAMPLES:
1. In-situ forming Microparticles
- injection solution contains drug + polymer
- once injected into body they solidify forming microparticles
- microparticles release drug slowly via diffusion + degradation
- Scaffolds e.g. Osteoset
- are small calcium sulphate tablets that stimulate bone growth
- place osteoset in gap (after surgical removal of mass)
- osteoset degrade after some weeks + are incorporated into bone
- incorporation helps with bone regeneration - Hydrogels
- can eb wound dressings, injections
Describe how “Non-biodegradable” implant works
with examples
Do not degrade in body + require surgical removal
EXAMPLES:
- Contraceptive implant (delivers hormones)
- Titanium implant (remains in body for life, keeps vertabrae together(
- Gastric stimulator (releives pain)
- Vascular graft (promotes angiogeneisis)
- Eluting stents (remain for life, keep artery open)
- Insulin pump (external ~ on skin)
- maintains consistent glucose levels
- Neurostimulator (for back pain)
- Pacemaker (sends electrical impulses to stimulate heart)
How are most implants formulated
- Casting
- Moulding
- 3D printing
