Myringopexy type titanium prosthesis

[0001] This invention relates to an ossicular prosthesis used for replacement and reconstruction and, more particularly, to a myringopexy type prosthesis.

[0002] Due to disease, trauma, or congenital malformation, the ossicles of the middle ear are sometimes damaged. Pexy is a medical term which generally refers to fixation. Myringo is a medical term generally referring to the ear drum. Myringopexy is a condition where the ear drum becomes fixed to the ossicles. More specifically, myringostapediopexy is a condition where the eardrum is fixed to the stapes with the stapes acting like a columella. Retraction of the ear drum occurs when negative pressure builds up in the middle ear from eustachian dysfunction. Specifically, the tube that leads from the ear to the back of the nose no longer passes air into the middle ear. Under such conditions, a retraction pocket can form in the eardrum and eventually the pocket may turn up skin, forming a skin cyst or cholesteatoma. The entire eardrum collapses and drapes over the bones of the middle ear. Further progression of retraction pockets can cause erosion of the middle ear bones or ossicles. While a ventilation tube is the first corrective step for retraction of the eardrum, in more severe cases a prosthesis may be needed to replace damaged bones.

[0003] The distance where a prosthesis may be used can be anywhere from 0.5 mm to 1 mm. Existing middle ear prosthesis used for myringopexy indications require major modifications at the time of surgery. This is because the length of the prosthesis is far too long for the distance between the eardrum and the mobile stapes. It is not uncommon that even when a prosthesis is modified, it is still too long to place between the eardrum and stapes. Additionally, existing prostheses are currently made from materials that are heavy or lack support.

[0004] One known prosthesis is mushroom-shaped having an enlarged head and a shaft. The current method of modifying such a prosthesis for myringopexy is to cut the shaft of the prosthesis as short as possible. Additionally, notches in the shaft may need to be added to better fit over the stapes. The current material of choice for such a prosthesis is Plasti-Pore which can be easily cut and shaped. Plasti-Pore is porous polyethylene which permits tissue ingrowth into the interconnecting pores of the implant material. Because of the sponge like characteristics of Plasti-Pore, sound conduction is dampened compared to using a more rigid material. A surgeon may also opt to use just the head or platform of a hydroxylapatite prosthesis. In such a case the shaft which is affixed to the hydroxylapatite head must be removed at the time of surgery. Alternatively, the head can be sold independently. Hydroxylapatite is a ceramic based material that closely mimics natural bone. However, weight of the material can be a concern.

[0005] The present invention is directed to improvements in a myringopexy type prosthesis.

[0006] In accordance with the invention, there is provided a myringopexy type prosthesis formed of a malleable body.

[0007] Broadly, there is disclosed in accordance with one aspect of the invention, a middle ear prosthesis comprising a one piece disk shaped prosthesis comprising a generally circular malleable body including a bore. The body engages a tympanic membrane and the bore receives a head of a stapes when implanted in a middle ear.

[0008] It is a feature of the invention that the bore comprises a through bore.

[0009] It is another feature of the invention that the body comprises a titanium body.

[0010] It is a further feature of the invention that the body comprises a ring, a hub and spokes connecting the ring to the hub. The hub may comprise a tubular hub having opposite arch-shaped notches to align with arches of the stapes.

[0011] It is still another feature of the invention that the body is cannulated on opposite sides of the bore to provide visibility of the stapes during implantation.

[0012] There is disclosed in accordance with another aspect of the invention a middle ear prosthesis comprising a body comprising an annular head, a collar, and a plurality of radially extending members connecting the head to the collar. The head engages a tympanic membrane and the collar receives a head of a stapes when implanted in a middle ear.

[0013] It is a feature of the invention that the plurality of radially extending members comprise a pair of aligned, malleable radially extending members to enable the head to be tilted relative to the collar.

[0014] It is another feature of the invention that diameter of the head is relatively large compared to height of the collar.

[0015] It is still another feature of the invention that an axis of the collar is perpendicular to a plane of the head.

[0016] In accordance with another aspect of the invention, there is disclosed the method of treating myringopexy comprising: removing an incus and malleus of a middle ear; providing a one piece disk shaped prosthesis comprising a generally circular malleable body including a bore; aligning the prosthesis with a stapes so a head of the stapes is received in the bore; and releasing a tympanic membrane so that it collapses on the body to retain the prosthesis in the middle ear.

[0017] Further features and advantages of the invention will be readily apparent from the specification and from the drawings.

[0027] Referring initially to FIG. 1, a human ear 10 includes an external 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. Referring to FIG. 6, the stapes 26 includes a loop or arch 28 connected to a footplate 30. A head 32 at the top of the arch 28 connects to the incus 24.

[0028] In accordance with the invention, a prosthesis 34 is used for treating myringopexy. The procedure for treating myringopexy in accordance with the invention is for a surgeon to initially remove the incus 24 and malleus 22. This leaves only the stapes 26 in the middle ear 14, as shown in FIG. 2. The prosthesis 34 is aligned with the stapes 26 to be received thereon. The tympanic membrane 18 can then be released so that it collapses on the prosthesis 34 to retain the prosthesis 34 in the middle ear 14.

[0029] Referring to FIGS. 3-5, the prosthesis 34 is illustrated. The prosthesis 34 comprises a one piece disk shaped body 36. Particularly, the body 36 comprises a generally circular malleable body including a bore 38. The body 36 engages the tympanic membrane 18 and the bore 38 receives the stapes head 32 when implanted in a middle ear 14. In the illustrated embodiment of the invention, the bore 38 comprises a through bore. The body 36 is formed of titanium. Advantageously, the body is made of a softer grade titanium, such as, for example, ASTM F67 grades 1 or 2.

[0030] More particularly, the body 36 comprises an annular ring 40 defining a head or platform. An outer edge of the ring 40 is turned downwardly at 42 to provide a smooth edge for engaging the tympanic membrane 18. A generally tubular collar or hub 44 defines the through bore 38. An upper edge of the hub 44 comprises a flange 46 coplanar with the ring 40. A pair of radially extending members, or spokes 48, connect the ring 40 to the hub 44. The body is cannulated on opposite sides of the hub 44, formed by arc shaped openings 50. The tubular hub 44 includes opposite arch shaped notches 52 opposite the flange end 46.

[0031] The body 36 is approximately 3.0 mm in diameter and has a height of approximately 0.5 mm to provide a disk shape. The canulation provided by the openings 50 provides maximum visibility of the stapes 26 and footplate 30 during surgery. The malleability of the titanium enables each side of the ring 40 to be bent and/or tilted along an axis of the spokes 48, as shown in FIG. 7 according to the patient's anatomy. The arch cut outs or notches 52 anatomically align with the arches 28, as shown in FIG. 6. Flexibility is provided by the head design which can be trimmed such as by removing a portion of the ring 40, as shown in FIGS. 8 and 9 to custom fit the patient. Titanium is considered a superior implant material because it weighs less than other implant materials and conducts sound vibrations well.

[0032] Referring specifically to FIGS. 2 and 6, during implantation, the prosthesis 34 is aligned with the stapes 26. The stapes head 32 is received in the bore 38. The notches 52 rest on the arches 28. The openings 50 provide visibility for the surgeon to see the arches 28 and foot plate 30 during implantation. According to the anatomy of the particular ear, the ring 40 can be bent, can be tilted as shown in FIG. 7, or can be trimmed as shown in FIGS. 8 and 9. Further, the body 36 can be covered with cartilage so that the tympanic membrane 18 rests on the cartilage, rather than the body 36. The body 36 floats on the cartilage, while the cartilage can grow into the tympanic membrane 18. The negative ear pressure causes the ear drum 18 to collapse onto the prosthesis 34 to provide pressure contact. The tension of the tympanic membrane 18 relative to the stapes head 32 sandwiches the prosthesis 34 to maintain it in position.

[0033] Thus, in accordance with the invention, there is provided a one piece disk shaped titanium prosthesis used for treating myringopexy. The prosthesis is designed for flexibility and stability and is lightweight and provides good sound conduction.