Hearing-aid anchoring element
View Patent ↗A hearing aid anchoring fixture ( 104 ) for anchoring a direct bone conduction hearing aid ( 108 ) to the skull bone ( 106 ), comprising a threaded portion ( 110 ) that has at least one cutting edge ( 118 ). Each cutting edge ( 118 ) has an adjacent cavity ( 120 ) having a volume V c . The threaded portion ( 110 ) has a thread depth d t being half of the difference between the maximum outer diameter d 1 of the threaded portion ( 120 ) and the inner diameter d 2 of the thread, where d t is at least 10% of the maximum outer diameter d 1 of the threaded portion ( 110 ) and where d t is less than 20% of the maximum outer diameter d 1 of the threaded portion ( 110 ). The fixture ( 104 ) may be equipped with a flange portion ( 114 ) that has an outer diameter d 3 being greater than the maximum diameter d 1 of the threaded portion ( 110 ).
1. A hearing aid anchoring fixture for anchoring a direct bone conduction hearing aid to a skull bone, comprising:
a threaded portion having a cutting edge, the cutting edge having a cavity defined therein, the cavity being adjacent to the cutting edge and having a volume V c ;
the threaded portion having a maximum outer diameter d 1 and an inner diameter d 2 ;
a thread having a thread depth d t being half of a difference between the maximum outer diameter d 1 of the threaded portion and the inner diameter d 2 of the thread, where d t is between 10% and 20% of the maximum outer diameter of the threaded portion,
the threaded portion having a surface layer, the surface layer having a thickness greater than 100 nanometers; and
a flange disposed at one end portion of the hearing aid anchoring fixture, the flange having a surface facing the threaded portion, the surface having a groove defined therein, the hearing aid fixture having a thread pitch t p , in an interval 0.5 mm≦t p ≦0.8 mm.
2. The hearing aid anchoring fire according to claim 1 , wherein the volume V c of the cavity is greater than 50% of a cut-off bone volume when the fixture has been screwed into a hole in the bone having a diameter that is 10% greater than the inner diameter d 2 of the thread.
3. The hearing aid anchoring fixture according to claim 1 wherein the fixture has a plurality of cutting edges where each cutting edge has an adjacent cavity defined therein.
4. The hearing aid anchoring fixture according to claim 3 , wherein total volume V ctot of the cavities is greater than 50% of the cut-off bone volume when the fixture has been screwed into a hole in the bone having a diameter that is 10% greater than the inner diameter d 2 of the thread.
5. The hearing aid anchoring fixture according to claim 1 , wherein the threaded portion has a relieving surface disposed behind the cutting edge.
6. The hearing aid anchoring fixture according to claim 3 , wherein the threaded portion has relieving surfaces disposed behind each of the cutting edges.
7. The hearing aid anchoring fixture according to claim 1 , wherein the threaded portion has a relieving portion at a distal end of the threaded portion and wherein the relieving portion has a smaller outer diameter d 4 than the maximum outer diameter d 1 of the threaded portion.
8. The hearing aid anchoring fixture according to claim 1 , wherein the threaded portion has a titanium oxide layer having a thickness that is at least 100 nm.
9. A hearing aid anchoring fixture for anchoring a direct bone conduction hearing aid to a skull bone, comprising:
a threaded portion having a cutting edge, the cutting edge having a cavity defined therein, the cavity being adjacent to the cutting edge and having a volume V c ;
the threaded portion havinga maximum outer diameter d 1 and an inner diameter d 2 ;
a thread having a thread depth d t being half of a difference between the maximum outer diameter d 1 of the threaded portion and the inner diameter d 2 of the thread. where d t is between 10% and 20% of the maximum outer diameter of the threaded portion;
the threaded portion having a surface layer, the surface layer having a thickness greater than 100 nanometers; and
a flange disposed at one end portion of the hearing aid anchoring fixture, the flange having a surface facing the threaded portion, the surface having a groove defined therein;
The surface layer including titanium oxide having a thickness that is at least 100 nm, the titanium oxide surface layer having a porous structure.
10. The hearing aid anchoring fixture according to claim 9 , wherein the treaded portion has a surface roughness S a , where 1 μm≦S a ≦3 μm.
11. The hearing aid anchoring fixture according to claim 9 , wherein the groove extends at least one turn on a side of the flange facing the threaded portion.