Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Patent
1997-06-19
1999-11-23
Yu, Mickey
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
623 16, 623 11, A61F 230, A61F 228, A61F 202
Patent
active
059892927
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a temporomandibular surgical implant comprising an L-shaped bracket having a first and a second leg extending transversely with respect to each other, wherein a portion of the first leg constitutes a mounting surface adapted to be mounted against an outer lateral surface of a patient's zygomatic arch, the mounting surface facing in a direction in which the second leg extends away from the first leg. More in particular, the invention relates to a temporomandibular joint prosthesis comprising such a temporomandibular surgical implant. Such an implant and such a prosthesis are known from U.S. Pat. No. 4,917,701.
A major problem associated with the use of temporomandibular surgical implants is to obtain a good fit between the temporal implant and the patient's bone structure. Many proposals have been made thus far to solve this problem.
In U.S. Pat. No. 3,597,643 a metallic articular eminence implant is disclosed which covers only the articular eminence of the temporal component of the joint. A good fit of the implant cannot always be achieved without surgical shaving of the eminence, even when a variety of implants of about at least ten sizes per side are available. Apart from the costs associated with providing such a number of implants ready for implantation (i.e. clean and sterilized), each time a patient is treated, the necessity of having to select the best design from such a number of implants during the surgical operation is cumbersome and difficult because the bone structure to which the implant has to be fitted is not well visible.
From the above-mentioned U.S. Pat. No. 4,917,701 an implant is known which comprises a rigid plate of which a part adapted to cover the mandibular fossa portion of the glenoid fossa is provided with a resilient layer to obtain a better fit to the mandibular fossa portion of the glenoid fossa and a more uniform distribution of loads. In implanted condition, this implant exerts considerable forces onto the fossa. However, the fossa is not suitable to bear such forces because the bone structures of the fossa are very thin. Furthermore, fitting this known implant to the articular eminence and to the zygcmatic arch is as problematic as in the previously described implant.
Another known approach is to determine the shape of the bone structure against which the implant is to be seated, in particular of the articular eminence, before surgical treatment. To obtain information regarding the shape of the relevant bone structure, CT-scans or X-ray pictures are made. On the basis of these scans a model is prepared to which the implant is custom-fitted. Although this approach is theoretically very promising, in practice a satisfactory fit is often not obtained, mainly because of a lack of accuracy, in particular where the surfaces of the bone structure are irregular and/or thin. Another disadvantage of custom-fitting is that it is very expensive and time consuming. During X-raying for obtaining information regarding the shape of the bone structure to which the implant is to be fitted, a patient is subjected to substantial irradiation doses.
It is an object of the present invention to provide a temporomandibular implant which provides an improved fit for a wide variety of patients, in a reduced variety of sizes and designs, which is easy to implant and entails substantially less cost than custom-fitting.
According to the present invention, this object is achieved by providing an implant of the type indicated in the opening paragraph hereof, with the characterizing features that the implant further comprises a fitting member having a seating surface which is adapted to be seated against the articular eminence of the patient in mounted position of the implant and that the fitting member is movably connected to the second leg in such a manner that in all possible positions of the fitting member relative to the bracket the seating surface faces at least substantially in a direction in which the first leg extends away from the second leg.
Since the fitting member carr
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patent: 5405393 (1995-04-01), Falkenstrom
patent: 5549680 (1996-08-01), Gordon
Stewart Alvin
Yu Mickey
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