Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Ear or nose prosthesis
Utility Patent
1998-12-01
2001-01-02
Willse, David H. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Ear or nose prosthesis
Utility Patent
active
06168625
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an ossicular prosthesis used for replacement and reconstruction and, more particularly, to an adjustable length ossicular prosthesis.
BACKGROUND OF THE INVENTION
Due to disease, trauma, or congenital malformation, the ossicles of the middle ear are sometime damaged. If this damage results in a discontinuity of bone between the tympanic membrane and the oval window, no sound conducts and hearing loss results. Some or all of these ossicles can be replaced with a small prosthesis. The material of choice for many years has been and, for some surgeons, continues to be the patient's own bone. Usually, the incus body will be harvested and reshaped into a strut that bridges whatever gap exists between the tympanic membrane and the oval window. Although this is an effective method of reconstruction, the time required to harvest and sculpt the incus bone into a usable prosthesis has caused many to search for a suitable synthetic replacement.
Plastic prostheses used for reconstruction of the ossicular chain have been used for some time. A total prosthesis is generally shaped like a nail or tack and replaces all three bones of the middle ear. A partial prosthesis replaces the malleus and the incus ossicles. This prosthesis is similar in shape, but has a hollow cylinder for the reduced portion of the prosthesis. The hollow cylinder fits over the head of the stapes. All plastic prosthesis require that a disc of cartilage be placed between the head of the implant and the tympanic membrane. These discs are harvested during surgery. The disc prevents the implant, in most cases, from eroding the tympanic membrane and becoming dislodged over time “extruding”.
Improvements have used movable joints to allow angular adjustment or bendable wire cores. Later, bioactive prostheses were developed. A bioactive material is one which incorporates into the surrounding tissues in the same manner that natural bone would. The bioactive material is usually a calcium phosphate ceramic, such as hydroxylapatite. To trim this type of prosthesis a diamond bur mounted on a surgical drill is used. However, due to the brittle nature of the material, it will sometimes shatter or chip during the trimming process. Bioactive bendable prosthesis use a bioactive ceramic head joined to a bioactive ceramic shaft by a bendable intermediate portion. Such a prosthesis can be angulated for better fit. However, the ceramic shaft must still be trimmed to length.
The present invention is directed to solving one or more of the problems discussed above in a novel and simple manner.
SUMMARY OF THE INVENTION
In accordance with the invention there is disclosed an ossicular prosthesis which is adjustable in length.
Broadly, there is disclosed herein an adjustable length ossicular prosthesis including a head formed of a bioactive or bioinert material for contacting a tympanic membrane when implanted in a human ear. The head includes a through opening. A flexible sleeve is mounted to the head at the through opening. The flexible sleeve includes a through opening coaxial with the head through opening. An elongate shaft has a near end extending through the sleeve through opening and the head through opening. The flexible sleeve through opening is adapted to grip the shaft under static conditions but permit the shaft to move axially to adjust shaft length. Means are associated with a distal end of the shaft for contacting a footplate or stapes when implanted in a human ear.
It is a feature of the invention that the flexible sleeve is formed of a biocompatible material. In one aspect the flexible sleeve is formed of an elastomer such as silicone. Alternatively, the flexible sleeve is formed of a plastic such as Teflon®. The sleeve is held to the head by an adhesive or by mechanical interlock.
It is another feature of the invention that the shaft is formed of a malleable material to produce a bendable shaft. According to one aspect of the invention the shaft is made of titanium.
It is a further feature of the invention that the shaft is defined by alternating enlarged portions and reduced portions and the sleeve expands as the enlarged portions pass through it and contract as the reduced portions pass through. This provides a slip lock mechanism.
It is an additional feature of the invention that the near end of the shaft on the opposite side of the head as the distal end is trimmed.
It is still another feature of the invention that the contacting means comprises a smaller bioactive head for contacting a footplate when implanted in a human ear.
In accordance with another aspect of the invention the contacting means further comprises a cylinder receivable on the smaller head. The cylinder has a counterbore for receiving the head of a stapes when implanted in a human ear.
It is yet another feature of the invention that the shaft extends slightly through the contacting means to form an extended tip to allow surgical fixation of the shaft to a footplate or stapes.
More particularly, an adjustable length prosthesis is used for ossicular replacement or reconstruction. The prosthesis uses a pair of bioactive heads connected by a shaft. The shaft is bendable to accommodate angulation for better anatomical fit. The shaft is flexibly received in the head and trimmable with a scissors or scalpel to simplify length adjustment and prevent chipping and breakage of the bioactive portion. The prosthesis can be used as a total or a partial prosthesis and need not be disassembled and reassembled during the trimming process. The prosthesis can be stabilized on the footplate with a sharpened shaft extension or wire core and can be used to protect the cochlea from pressure trauma.
Further features and advantages of the invention will be readily apparent from the specification and from the drawing.
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Jackson Suzette J.
Willse David H.
Wood Phillips VanSanten Clark & Mortimer
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