Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Utility Patent
1999-02-19
2001-01-02
Milano, Michael J. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
C623S021120
Utility Patent
active
06168630
ABSTRACT:
BACKGROUND OF THE INVENTION
The human wrist can execute pivoting movements in all spatial directions, the most important being the pivoting in the dorsal-palmar plane. In a known wrist prosthesis (DE-U 295 00 476), two articulations are therefore provided one behind the other or one within the other, one of them being designed as a transverse axis articulation which is able exclusively to execute a hinge movement for the dorsal-palmar pivoting, the other of them being designed as an elongate socket which is arranged to move essentially transverse to the former. In the case of an unstable ligament apparatus or certain muscle imbalances, prostheses are preferred in which the transverse pivoting is suppressed, with only the transverse axis articulation being provided (DE-U 70 12 087). Hitherto, it has been necessary to decide in each case between different makes, which is difficult when the decision can only be made during surgery.
SUMMARY OF THE INVENTION
The invention is therefore based on the object of making available a prosthesis which allows a decision to be made during surgery.
Accordingly, the proximal part of the transverse axis articulation is connected releasably to the radial element to be anchored in the ulna and is either designed to be rigid per se or is equipped with the further articulation permitting the transverse movement. A prosthesis system is thus obtained which makes it possible to make a decision during surgery as to whether a transverse mobility should be allowed or not and, accordingly, one or other of the alternative embodiments of the proximal part of the transverse axis articulation is used, while the other prosthesis parts remain the same. In particular, this system makes it possible for those elements of the prosthesis to be anchored in the bone to be implanted before a decision has to be taken regarding the transverse mobility of the prosthesis. A subsequent exchange is also made possible by this means.
The connecting arrangements provided between the proximal part of the transverse axis articulation and the radial element are expediently equipped for transmitting force with positive locking. According to a further feature of the invention, these can be pushed into one another essentially in the ulnoradial direction. In this way, a reliable connection is achieved which is independent of any screwing or clamping mechanisms. On the other hand, the said prosthesis part can be inserted without any great distraction between the already implanted carpal and radial elements.
The transverse axis articulation comprises, on one side, a T-type journal and, on the other side, a bearing part which comprises two aligned bores for receiving the T-type journal or its bearing. The T-type journal is pushed into these bores from one end, the outer of these two bores being slotted in the longitudinal direction to allow passage of the central pin of the T-type journal. The insert opening at the end of the bore is then closed. According to the invention, a threaded closure can be provided for this purpose.
The boundary between the mutually releasable distal and proximal parts of the transverse axis articulation can coincide with these bearing surfaces. However, since the bearing functions on the one hand, and the functions relating to the releasability and mutual fixing of the articulation parts, on the other hand, do not necessarily go together, it may be more expedient for all the bearing elements of the transverse axis articulation to be arranged on the distal part.
The carpus element has a plurality of distally extending pegs which are to be inserted into the metacarpal bones and which are connected by a transverse member extending essentially perpendicular to the pegs. It is known to arrange the articulation axis of the transverse axis articulation at an acute angle thereto. According to the invention, this angle is chosen in a range between 0° and 15°, preferably in a narrower range of 5° to 10°.
In the known prosthesis, the socket of the additional universal joint is arranged steeply inclined in relation to the transverse direction. According to the invention, this inclination is reversed in favor of an almost symmetrical design in which the edge tangent, i.e. the connecting line of the edges of the articulation surface of the socket in the palmar plane, encloses an angle of at least 5° and at most 25°, preferably from 10° to 15°, with the radius transverse direction or the complementary angle with the longitudinal direction of a stem to be fixed in the ulna. This angle can be greater in the sagittal plane. The difference between this angle and the angle mentioned in the preceding paragraph gives the directional difference between the carpus element and the radius element, which preferably lies between 0° and 10°. Correspondingly, the angle which the bearing axis encloses with the radius transverse direction, in the rigid version of the proximal part of the transverse axis bearing, is advantageously of the same order of magnitude.
REFERENCES:
patent: 4259752 (1981-04-01), Taleisnik
patent: 4307473 (1981-12-01), Weber
patent: 5314485 (1994-05-01), Judet
patent: 5755804 (1998-05-01), Schmotzer et al.
patent: 5766258 (1998-06-01), Simmen
patent: 5782926 (1998-07-01), Lamprecht
patent: 41398 (1970-03-01), None
patent: 24 45 758 A1 (1975-04-01), None
patent: 27 26 379 A1 (1978-04-01), None
patent: 30 08 292 A1 (1980-09-01), None
patent: 44 06 090 A1 (1995-08-01), None
patent: 44 33 483 C2 (1997-02-01), None
patent: 0 454 646 A1 (1991-10-01), None
patent: 0 532 440 A1 (1993-03-01), None
Keller Arnold
Thabe Heiner
Alix Yale & Ristas, LLP
Milano Michael J.
Pellegrino Brian
Waldemar Link (GmbH & Co)
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