Implantable device having osseointegrating protuberances

Abstract

An implantable device for mounting to a patient's bone includes a housing and at least one osseointegrating protuberance. The housing includes a surface having an abutting portion configured to abut the bone when the housing is implanted in the patient, the abutting portion defining a housing axis orthogonal to the surface. The at least one osseointegrating protuberance: extends from the surface of the housing; is adapted to abut the patient's bone; and has a substantially smooth shaft.

What is claimed is: 
     
         1 . An implantable device for mounting to a patient's bone, the device comprising:
 a housing including a surface having an abutting portion configured to abut the bone when the housing is implanted in the patient, the abutting portion defining a housing axis orthogonal to the surface; and   at least one osseointegrating protuberance extending from the surface of the housing;
 the at least one protuberance being adapted to abut the patient's bone; and 
 the at least one protuberance having a substantially smooth shaft. 
   
     
     
         2 . The implantable device of  claim 1 , wherein the at least one protuberance includes:
 osseointegrating first and second protuberances extending from the surface;
 the first and second protuberances each being adapted to abut the patient's bone; and 
 the first and second protuberances each having a substantially smooth shaft. 
   
     
     
         3 . The implantable device of  claim 1 , wherein:
 the at least protuberance is configured to prevent substantial relative lateral movement between the housing and the patient's bone.   
     
     
         4 . The implantable device of  claim 1 , wherein:
 the at least one protuberance is formed of one of titanium and a titanium alloy.   
     
     
         5 . The implantable device of  claim 1 , wherein the at least one protuberance includes:
 a core member; and   a coating on the core member, the coating being one of titanium and titanium alloy.   
     
     
         6 . The implantable device of  claim 1 , wherein:
 the at least one protuberance has a surface treatment that encourages osseointegration.   
     
     
         7 . The implantable device of  claim 1 , wherein:
 the surface of the housing is coated with a material configured to prevent osseointegration.   
     
     
         8 . An implantable component of a tissue stimulating prosthesis, the implantable component comprising:
 a housing including a surface having an abutting portion configured to abut the bone when the housing is implanted in the patient, wherein the abutting portion defines a housing axis orthogonal to the surface; and   one or more components of the prosthesis mounted in the housing; and   at least one osseointegrating protuberance extending from the surface of the housing;
 the at least one protuberance being adapted to abut the patient's bone; and 
 the at least one protuberance having a substantially smooth shaft. 
   
     
     
         9 . The implantable component of  claim 8 , wherein the at least one protuberance includes:
 osseointegrating first and second protuberances extending from the surface;
 the first and second protuberances each being adapted to abut the patient's bone; and 
 the first and second protuberances each having a substantially smooth shaft. 
   
     
     
         10 . The implantable component of  claim 8 , wherein:
 the at least protuberance is configured to prevent substantial relative lateral movement between the housing and the patient's bone.   
     
     
         11 . The implantable component of  claim 8 , wherein:
 the at least one protuberance is formed of one of titanium and a titanium alloy.   
     
     
         12 . The implantable component of  claim 11 , wherein the at least one protuberance includes:
 a core member; and   a coating on the core member, the coating being one of titanium and titanium alloy.   
     
     
         13 . The implantable component of  claim 8 , wherein:
 the at least one protuberance has a surface treatment that encourages osseointegration.   
     
     
         14 . The implantable component of  claim 8 , wherein:
 the tissue-stimulating prosthesis is a cochlear implant.   
     
     
         15 . The implantable component of  claim 14 , wherein:
 the one or more components mounted in the housing are configured to function as a stimulator unit of the cochlear implant.   
     
     
         16 . A method for implanting an implantable device having a housing with an abutting surface configured to prevent osseointegration of the housing with a patient's bone and at least one osseointegrating protuberance extending from the housing, the method comprising:
 forming a pocket in the patient's bone to receive the housing;   positioning the housing in the pocket such that the at least one protuberance is in direct contact with a surface of the patient's bone forming the pocket; and   allowing osseointegration of the at least one protuberance to occur.   
     
     
         17 . The method of  claim 16 , wherein:
 the allowing osseointegration is accomplished without insertion of the at least one protuberance into the surface of the patient's bone that comprises the pocket,   whereby when the at least one protuberance is osseointegrated the abutting surface of the housing is not osseointegrated.   
     
     
         18 . The method of  claim 16 , wherein:
 the at least one protuberance has a longitudinal axis that lies in a same imaginary plane relative to an implant axis that is substantially orthogonal with the housing abutting surface; and   the method further comprises:
 positioning the at least one protuberance adjacent to the patient's bone such that the implant axis is substantially orthogonal to the patient's bone and such that at least a portion of the housing abutting surface is spaced from patient's bone before osseointegration occurs. 
   
     
     
         19 . The method of  claim 16 , wherein:
 the tissue stimulating prosthesis is a cochlear implant.   
     
     
         20 . The method of  claim 16 , wherein the forming a pocket comprises:
 selecting as the patient's bone one from among the group consisting of a periosteum, skull, and a mastoid process.