Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Reexamination Certificate
1998-09-16
2001-04-24
Hirsch, Paul J. (Department: 3732)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
C623S016110
Reexamination Certificate
active
06221110
ABSTRACT:
The invention relates to a set of prostheses of different sizes according to the preamble of claim
1
.
Sets of prostheses of different sizes are made available by prosthesis manufacturers in order to take into account the different sizes of bones which are found in different patients. The surgeon selects the suitable prosthesis for each individual case from the set which is made available to him.
Furthermore, there are two fundamentally different classes of prosthesis on the market, namely so-called shaft prostheses, which are connected to the wall of a cavity produced in the bone using a cement, and so-called cement-free prostheses, in which the anchoring section introduced into the bone end comprises cavities or openings into which spongiosa can grow during the healing process. Which of these two basic types is used by the surgeon in each individual case needs to be determined prior to the operation.
For some operations, it would be desirable if it were possible to decide between a cemented prosthesis and a prosthesis implanted without cement during the course of the operation depending on the conditions which are encountered.
In order to attain this object, according to the invention a set of prostheses of different sizes is proposed having the features disclosed in claim
1
.
According to the invention, the surgeon is therefore provided with a pair of alternative prostheses for use for each standard size, one of which corresponds to the cemented type, the other to the cement-free type. These two prostheses have the same basic geometry, although the exposed external contour of the anchoring section of the cement-free prosthesis lies beyond the clear external contour of the cemented prosthesis; in practice, the distance between these two contours corresponds approximately to the desired thickness of the cement layer between the internal surface of the bone cavity and the external surface of the prosthesis shaft when cementing the cemented prosthesis in place.
For both prostheses, the same resectioning of the corticalis of the end section of the bone which is to be connected to the prosthesis is therefore to be carried out, and the formation of the cavity is also effected in essentially the same manner (with the exception of a possible fine finishing).
For a first provision of a bone with a prosthesis, the cement-free prosthesis is usually preferred, since following the healing process this most closely reproduces the natural structure of a healthy bone. If, after carrying out the appropriate preparation of the bone end, the surgeon ascertains that the cement-free prosthesis is not as suitable after all for the operation which has been performed as the cemented prosthesis, he can easily use a cemented prosthesis instead of the cement-free prosthesis provided.
Advantageous developments of the invention are contained in the subclaims.
The distances given in claim
2
between the clear external contours of the cement-free prosthesis and the cemented prosthesis result in particularly advantageous fitting conditions and particularly advantageous thicknesses of cement layers.
The developments of the invention according to claims
3
to
6
have as their subject matter geometries of the anchoring sections which adapts particularly well to the corticalis of a thigh bone in such a manner that a distance which is substantially constant over the cavity is formed between the clear external contour of the anchoring section of the prosthesis and the internal surface of the cavity defined by the corticalis.
If a tool is used as depicted in
FIGS. 7 and 8
for the finishing of the internal surface of the cavity accommodating the anchoring section of the prosthesis which is to be incorporated, then it is ensured on the one hand that an optimal thickness of the cement layer used for the cementing in place is obtained where a cemented prosthesis is used, and on the other hand where a cement-free prosthesis is incorporated that the latter sits with snug friction locking in the cavity.
The above-mentioned advantages are preferably obtained in practice with relationships between the clear external contours of the two prostheses and the tool as depicted in
FIGS. 7 and 8
.
FIGS. 7 and 8
depict tools which ensure a finishing of the cavity which precisely matches the contour and on the other hand are very simple to manufacture.
REFERENCES:
patent: 3938198 (1976-02-01), Kahn et al.
patent: 4064567 (1977-12-01), Burstein et al.
patent: 4068324 (1978-01-01), Townley et al.
patent: 4435854 (1984-03-01), Keller
patent: 4570271 (1986-02-01), Sump
patent: 4728335 (1988-03-01), Jurgutis
patent: 5180395 (1993-01-01), Klaue
patent: 5387243 (1995-02-01), Devanathan
patent: 5507814 (1996-04-01), Gilbert et al.
patent: 5571185 (1996-11-01), Schug
patent: 5766261 (1998-06-01), Neal et al.
patent: 5807407 (1998-09-01), England et al.
patent: 230006 (1987-07-01), None
patent: 1627171 (1991-02-01), None
Hirsch Paul J.
Priddy Michael B
LandOfFree
Set of prostheses of different sizes does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Set of prostheses of different sizes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Set of prostheses of different sizes will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2453664