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U S Patent 0 s 3 US 7 955 386 B2
This application is a continuation-in-part of Ser. No. 10/976,638, filed Oct. 29, 2004 now U.S. Pat. No. 7,288,113, and a continuation-in-part of Ser. No. 11/428,672, filed Jul. 5, 2006, which is a continuation of U.S. Ser. No. 10/666,451, filed Sep. 19, 2003, now issued as U.S. Pat. No. 7,087,081, and claims benefit ofboth Ser. Nos. 60/823,914, filedAug. 30, 2006, and 60/853,938, filed Oct. 24, 2006.
This invention relates to an ossicular prosthesis used for replacement and reconstruction and, more particularly, to a middle ear prosthesis of a deformable material.
BACKGROUND OF THE INVENTION
Due to disease, trauma, or congenital malformation, the ossicles of the middle ear are sometimes damaged. The delicate joint between the incus and the stapes is termed the incudo-stapedial joint (ISJ). The ISJ is a cartilaginous joint having a tendency to ossify in older humans. When the joint is interrupted due to erosion of the joint or the incus itself, vibrations can no longer be transmitted from the incus to the stapes. The result is a conductive hearing loss related to the disrupted ossicular chain.
Medical implants have been developed to reconstruct the ossicular chain when a portion of the incus is missing. However, the entire incus has to be removed and replaced with a prosthesis. This approach destroys the natural joint between the incus and stapes and the lever firnction of the incus in relationship to the malleus and stapes.
One particular implant to address conditions when only the ISJ is eroded or ossified is shown in U.S. Pat. No. 5,306,299. This prosthesis is made from a hydroxylapatite. Particularly, the prosthesis comprises a block of hydroxylapatite having a cylindrical cavity intersecting with a U-shaped channel. The prosthesis cannot be adjusted to conform to various sized incus and stapes. As such, the prosthesis must be provided in different sizes for different size ossicular chains. Because of its mass and lack of features to stabilize its connection to the incus and stapes, it is possible for the prosthesis to migrate and extrude through the ear drum over a period of time. Concems over the weight of the ceramic material and the overall mass of the prosthesis have been raised. Also, the hydroxylapatite material is inherently fragile, prone to breakage and cannot be easily modified to custom fit the incus or stapes head.
An alternative ISJ prosthesis is disclosed in U.S. Pat. No. 5,514,177. This prosthesis is formed of composite construction using pieces of different materials secured together such as by welding.
Certain ossicular prosthetics require that they be manually crimped to the bone. Fixating or crimping an ossicular prosthesis to bone can be diflicult due to problems with prosthesis stability, surgical exposure, appropriate clamping, etc. It is desirable to have a prosthesis that is “self-crimping”. Ideally, the self crimping prosthesis should be low profile and provide secure, stable fixation. It should also be easy to apply without damaging the ossicles and apply a small amount of pressure to the ossicles so as to minimize the potential for pressure necrosrs.
U.S. Pat. Nos. 6,197,060 and 6,554,861 describe various ossicular prostheses that include a shape memory wire or
ribbon reversely tumed on itself to form an open-ended bight. The bight is opened with a tool and then automatically closed and crimped about an ossicle upon the application of a signal such as heat. However, such a bight structure is ineffective for coupling various ossicular bones together, either because of the anatomy or because of the lack of the stability provided.
The present invention is directed to improvements in middle ear prosthetics.
In accordance with one aspect of the invention, there is provided an adjustable middle ear prosthesis.
Broadly, there is disclosed in accordance with one aspect of the invention, an adjustable middle ear prosthesis comprising a unitary body of deformable material capable of retaining different shapes. The body can be reshaped to fit to and retain ossicular bones, such as the stapes and the incus, in a desired relationship. The body is preferably made of a malleable titanium, such as soft unalloyed titanium, or a shape memory material such as nickel-titar1ium or a polymer.
In one embodiment of the invention, the body comprises a generally tubular first cavity for receiving a head of a stapes and an elongate second cavity extending generally perpendicular to the generally tubular first cavity for receiving an incus. The body comprises a collar defining the generally tubular first cavity. The collar may have a longitudinally extending through slot, and may include a pair of opposite longitudinally extending through slots. The body comprises a generally semi-cylindrical wall connected to opposite parallel walls having inwardly extending flanges defining the elongate second cavity. The semi-cylindrical wall may include a keyhole slot. The opposite parallel walls may be connected to the semi-cylindrical wall by bridges to define elongate slots between the opposite parallel walls and the semi-cylindrical wall. The flanges are spaced apart to define a cavity slot. The opposite parallel walls with flanges extending inward therefrom together define a generally U-shaped wall. The U-shaped wall and semi-cylindrical wall together define the second cavity extending generally perpendicular to the first cavity for receiving an incus.
According to a second embodiment of the invention, an ISJ prosthesis is provided including first and second slotted tubular portions perpendicularly arranged relative to each other. The first slotted tubular portion includes one or more wall portions that are opened and the second slotted tubular portion includes fingers that are opened. The wall portions and fingers are deformed about the stapes and incus, preferably by the application of heat, to stably hold the stapes and incus in the desired anatomical relationship.
According to third embodiment of the invention, an angular piston prosthesis is provided in w11ich a slotted tubular portion is provided on a rod element. The slotted tubular portion includes one or more arms that can be deformed about the incus, such as by application of heat, and the rod element is sized in length to extend from the incus to the stapes footplate or oval window.
According to a fourth embodiment of the invention, a partial ossicular replacement prosthesis (PORP) is provided. The prostheses includes an inverted cup defining a cavity for the head of the stapes, a shaft extending from the cup, and a disc at the end of the shaft for placement against the tympanic membrane. The disc may be longitudinally displaceable on the shaft to adjust the length of the prosthesis. According to the invention, the cup includes at least one slot defined in a wall thereof permitting the circumference of the wall to be
defonned into an open position to facilitate receiving the head of the stapes and then closed upon application of heat to retain the stapes.
According to a fifth embodiment of the invention, another PORP is provided including a shaft, a disc at one end, and a mount for engaging the head or capitulum of the stapes at the other end. The mount includes two side walls each provided with a longitudinal recess in which to receive the arch of the stapes. Between the side walls an anchor tab is provided and has a length suflicient to extend across the diameter of the mount. The tab is defonned open to pennit the arch of the stapes access into the recesses. Then, upon application of heat to the tab, the tab automatically defonns to bend through the arch and under the capitulum to lock the stapes to the PORP.
Further features and advantages of the invention will be readily apparent from the specification and from the draw
ings. BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective, partial cross-section of the anatomy of an ear showing a nonnal ossicular chain;
FIG. 2 is a perspective view of an adjustable incudo-stapedial joint (ISJ) prosthesis in accordance with the invention;
FIG. 3 is a top plan view ofthe ISJ prosthesis of FIG. 2;
FIG. 4 is a bottom plan view ofthe ISJ prosthesis ofFIG. 2;
FIG. 5 is a front elevation view of the ISJ prosthesis of FIG. 2;
FIG. 6 is a rear elevation view of the ISJ prosthesis of FIG. 2;
FIG. 7 is a side elevation view of the ISJ prosthesis of FIG. 2;
FIG. 8 is a perspective view illustrating the ISJ prosthesis in accordance with the invention implanted in a human ear;
FIG. 9 is an upper front perspective view of an ISJ prosthesis in accordance with an altemative embodiment of the invention;
FIG. 10 is an upper rear perspective view of the ISJ prosthesis of FIG. 9;
FIG. 11 is a lower front perspective view of the ISJ prosthesis of FIG. 9;
FIG. 12 is a lower rear perspective view of the ISJ prosthesis of FIG. 9;
FIGS. 13-16 correspond to FIGS. 9-12, respectively, showing the ISJ prosthesis defonned for packaging and pre-implantation;
FIG. 17 is an upper rear perspective view of an angular piston prosthesis in accordance with the invention;
FIGS. 18 and 19 are perspective views of an ossicular replacement prosthesis with a cup portion shown as machined;
FIG. 20 is a perspective view similar to FIG. 18 showing the cup in a shape set position;
FIG. 21 is a perspective view similar to that of FIGS. 18 and 20, showing the cup in an open position for packaging and pre-implantation;
FIG. 22 is a side elevation view of a partial ossicular replacement prosthesis with a locking ann in a set position; and
FIG. 23 is an elevation view similar to FIG. 22 showing the locking arm in the open position for packaging and preimplantation.
DETAILED DESCRIPTION OF THE INVENTION
Referring initially to FIG. 1, a human ear 10 includes an extemal or outer ear 12, a middle ear 14 and an inner ear 16.
A tympanic membrane 18, also called the ear drum, separates the outer ear 12 from the middle ear 14. The middle ear 14 includes an ossicular chain 20 comprising three small bones that are connected and transmit the sound waves from the ear drum 18 to the inner ear 16. The three small bones are called the malleus 22, the incus 24, and the stapes 26. The stapes 26 includes a loop or arch 28 connected to a footplate 30. A head (capitulum) 32 at the top of the arch 28 connects to the lenticular process of the incus 24 at an incudo-stapedial joint (ISJ) 34.
In accordance with the invention, an ISJ prosthesis 40, see FIGS. 2-7, is used when only the ISJ and possibly a short segment of the distal aspect of the long arm of the incus is eroded or ossified. In accordance with this disclosed aspect of the invention, the ISJ prosthesis 40 contains a series of slots enabling the prosthesis to be adjusted in multiple planes to provide a custom fit to either the incus 24 or the stapes head 32.
The ISJ prosthesis 40 is of unitary construction manufactured, such as by machining, to form a one-piece defonnable, malleable metal body 42. For ease of description herein, the body 42 is described referring to the left-most part in FIGS. 3 and 4 as the front and the right-most part in FIGS. 3 and 4 as the rear. It should be understood, however, that these relative tenns are for reference only in describing the device and do not describe any particular characteristics of the prosthesis 40.
The body 42 comprises a generally semi-cylindrical wall 44 having a top end 46 and a bottom end 48. A rounded notch 50 is provided proximate the top end 46. A keyhole slot 52 is provided through the semi-cylindrical wall 44 originating at the bottom end 48.
The semi-cylindrical wall 44 is connected to opposite arcuate wall portions 54 and 56 at its bottom end 48. The arcuate wall portions 54 and 56 have respective distal edges 58 and 60 spaced apart to define a collar slot 62. The semi-cylindrical wall bottom end 48 and the arcuate wall portions 54 and 56 form a bottom tubular wall 64 slotted with the keyhole slot 52 and the collar slot 62. The slotted tubular wall 64 defines a generally tubular cavity 66 extending along a first axis A1. The tubular cavity 66 is adapted for receiving the head 32 of the stapes 26 during implantation.
Opposite parallel walls 68 and 70 extend tangentially from the semi-cylindrical wall 44 and are connected thereto by respective bridges 72 and 74. Top rear corners 69 and 71 are rounded. The walls 68 and 70 have respective lower edges 76 and 78 spaced above the respective arcuate wall portions 54 and 56 to define spacer slots 80 and 82. The opposite parallel walls 68 and 70 have inwardly extending, spaced apart flanges 84 and 86 to define an elongate slot 88 therebetween. The opposite parallel walls 68 and 70 are spaced from the semi-cylindrical wall 44 above the respective bridges 72 and 74 to define respective front slots 90 and 92.
The semi-cylindrical wall 44 at the top end 46 and the side walls 68 and 70 form a generally U-shaped wall 94 defining an elongate cavity 96 extending along a second axis A2 substantially perpendicular to an axis A1 for receiving an incus 24. As is apparent, the elongate cavity 96 is open from the top or rear for receiving an incus 24 with the incus 24 resting on the flanges 84 and 86. As is apparent, the orientation of the elongate cavity 96 is generally perpendicular to the tubular cavity 66 owing to the conventional relationship in orientation between the incus 24 and stapes head 32.
In accordance with the invention, the body 42 is of one piece construction of a defonnable or crimpable (i.e., malleable) metal capable of retaining different shapes. In one exemplary embodiment of the invention, the ISJ prosthesis 40