2. Biocompatibility
• Multidimensional concept
• Scales
– Not physically modified by soft tissue
– Not capable of inciting an inflammatory or foreign body
reaction
– Not capable of producing a state of allergy or
hypersensitivity
– Chemically inert
– Noncarcinogenic
– Capable of resisting strain
– Capable of fabrication in the form desired
– Capable of sterilization
7. Polymers
• Aggregate of atoms usually based on carbon and
linked together to form chains
– Transformation
• Implanted polymer
– Fibrous capsule
• Silastic
– Nonadherant capsule
– Post op failure
• Poly(ethylene) – TORP / PORP
– Embedded in connective tissue
11. Prosthetic Implants
• Silicone rubber - life like texture & color
• Methods:
– Traditionally with adhesives uncertain
– Osseo-integration: exploited by Tjellstorm et al
• Surgery:
– 2 staged
26. MIDDLE EAR IMPLANTS
BASIC DESIGN
• Microphone
• Amplifier
• Transducer
– Convert electrical energy to mechanical energy
– Coupled directly or indirectly to ossicular chain
• Mech of action
– Piezoelectric: direct contact with ossicles
– Electromagnetic : indirect contact with ossicles
27. MIDDLE EAR IMPLANTS
Ossicular coupling:
• Piezoelectric transducer
– Head of stapes : Rion , Envoy
– Incus body : TICA
• Electromagnetic transducer
– Incus: Vibrant sound bridge
– IS joint: Soundtec direct drive hearing system
28. VIBRANT SOUNDBRIDGE
• Partially implantable electromagnetic hearing aid
• Ist to be commercially available :1998 in Europe
• EM transducer uses vibrating ossicular prosthesis
containing rare earth magnet
• External device worn BTE
• Electrically connected to internal receiver
• Demodulator prevents overstimulation
• Floating mass transducer: firmly attached to incus
with titanium clip
31. MIDDLE EAR TRANSDUCER(MET)
• Otologics MET
• Fully implantable device
• Parts
– Subcutaneous Microphone
– Electronic reciever
– Transducer probe(Aluminium oxide probe tip)
connected to Body of incus
• Currently under FDA approved clinical trials in USA
32. SIMEDH
– Semi Implantable Middle ear Electromagnetic Hearing
Device
– Uses electromagnetic transducer
– Magnet cemented to body of incus
– EM coil fixed by titanium frame to temporal bone
– Lacks benefit over conventional hearing aids
– Implanted in cats
– Awaited human trials
33. IMPLANTABLE HEARING AIDS
• Advantages of implantable hearing aids
– Increased gain & dynamic range
– Reduced feedback
– Reduced daily maintenance
– Cosmetic
• Disadv:
– High initial cost
– Risk of surgery
– Difficulty in long term maintenance
34. BAHA
• Bone Anchored Hearing Aid
• 1960’s: First used in Sweden
• Principle
• Parts
– Fixture
– Bone anchored abutment
– Sound processor: ear level/body level
• Candidacy:
– Cochlear threshold <45dB for ear level BAHA
– <65dB for body level BAHA
35. • Indication:
– Unilateral deafness
– AC hearing aid user + chronically draining ear
– ACHA user + discomfort due to otitis externa /COM
– ACHA user + radical mastoidectomy/large meatoplasty
: uncontrollable feedback
– Congenital EAC malformation+ functional cochlea
– Any pt using conventional BC hearing aid
– OS, tympanosclerosis, canal atresia+ c/i to repair :
only hearing ear
– Unilat SNHL>90dB with SDS<20%
36. • Contra indications:
– Poor hygiene
– Insufficient bone volume or inadequate bone
quality
– Age<5 yrs
– Emotional instability , drug abuse
– BC threshold >45 dB & SDS>60%
37. • Implant material
– Pure titanium: 99.75%pure
– Titanium alloy: 90% Titanium+ 6% Al+ 4%
Vanadium
– Form tight bond & corrosion resistant oxide layer
– No toxicity or carcinogenesis reported
– Does not interfere with MRI
39. Medpor Implant
• PHDPE (Porous High density polyethylene)
formed by lattice with 100-250 micrometre
pores
• Function:
– Fibrovascular ingrowth
– Pore size allows ingress of macrophages
44. Materials used for Injection laryngoplasty
Material Location Amt injected Duration Viscosity Needle
guage
FDA
approval
Teflon Lateral to
Vocal lig.
Exact amt. Permanent Low 18 Yes
Bovine
Collagen
Lateral to
vocal lig.
Overinject 6 mths. High 27 No
Human
Collagen
Lateral to
vocal lig.
Overinject 6 mths. High 27 – 30 No
Alloderm
/ Cymetra
Lat. To
vocal lig.
Overinject 6 – 9 mths. Low 22 Yes
Fascia Lat. To
vocal lig./
In
vibratory
memb.
Overinject 3 mths. High 18 – 22 NA
45. Materials used for Injection laryngoplasty
Material Location Amt injected Duration Viscosity Needle
guage
FDA
appr
oval
Fat Lateral to
vocal lig. /
In
vibratory
memb.
Overinject 3 mths. High 18 – 22 NA
Silicone Lateral to
vocal lig.
Overinject 6 mths. Stable non
viscous
material
18 – 22 NA
Gelfoam
paste
Lateral to
vocal lig.
Exact
Temporary
effect is desired
6wks – 3
mths.
18 – 19 NA
Hydroxylap
atite
Lateral to
vocal lig.
Slightly
overinject
2 yrs. Low 26 Yes
Hyaluronic
acid
In
vibratory
memb.
Slightly
overinject
2 yrs. High 26 No
47. KEELS
• Inert ptfluoroethylene
• Indications :
– To prevent adhesion formation
– Restenosis
– Web formation
• Extend : Cricoid to 2- 3 mm
above the post. Commisure
• Angle at superior portion
120° - Minimize granulation
formation
• Placement : Endoscopic /
open
48. Stents
• Internal laryngeal stent in order of preference
– No ideal laryngeal stent available
– 1. Montgomery laryngeal stent
– 2. Aboulker stent
– 3. Rolled Silastic sheeting
– 4. Sterile glove finger packed with foam
• Endolaryngeal stenting
– Provide internal support to laryngeal skeleton
– Maintain lumen of larynx and adhesion formation
– Maintain scaphoid shape of anterior commissure
– to separate Massive / multiple mucosal injuries
Comminuted and multiple displaced fractures of the
laryngeal skeleton
51. Montgomery’s T tube stent
• 1965
• Soft stent / 12 mths.
• Silicon stent
• Long central lumen & smaller
lumen projecting from side
( 90 / 75°)
• Not used in children < 2 yrs.
60. Totally Implantable Cochlear Amplifier(TICA)
• Piezoelectric middle ear implant
• Sensor or microphone implanted subcutaneously
in EAC adjacent to TM
• Actuator couples to incus
• Device can be shut off manually/remote
• Preservation of battery
• Made of titanium: MRI compatible
• Problems of feedback required ossicular chain dis
articulation
• Not in use
61. Direct Drive Hearing System
• Soundtec DDHS is semi implantable hearing
aid
• Uses electromagnetic transducer
• Titanium encased magnet attached to IS joint
• EM coil deep in the canal encased
• Currently not in use
62. RION- PIHA
• Partially implantable piezoelectric hearing aid
• Useful in patients with severe ossicular chain
necrosis
• Mixed HL <50dB in speech frequency
• Actuator attached to stapes head
• Other end fixed over mastoid
• Microphone : BTE external device
• Low acoustic feedback
• Complication : device failure , post auricular
fistula
