Source: https://patents.justia.com/patent/4822370
Timestamp: 2020-02-22 17:05:21
Document Index: 79500737

Matched Legal Cases: ['art 20', 'art 20', 'art 20', 'art 20', 'arts 20', 'arts 20']

US Patent for Hip joint femoral prosthesis Patent (Patent # 4,822,370 issued April 18, 1989) - Justia Patents Search
Justia Patents US Patent for Hip joint femoral prosthesis Patent (Patent # 4,822,370)
Jun 20, 1988 - Orthoplant Endoprothetik
Given a hip joint femoral prosthesis having a shaft, a spherical head and a connecting part between the shaft and the head. Disposed at the proximal end of the shaft and in the head in each case is a conical boring. Located at the shaft side end and at the head side end of the connecting part is a socket cone cooperating with each conical boring. The longitudinal axis of the first socket cone and the longitudinal axis of the second socket cone of the connecting part intersect at a predetermined angle 0.ltoreq..beta..ltoreq.50.degree. (zero is less than or equal to beta and beta is less than or equal to 50.degree.), in order to be able to adapt better the relative position of the head to the shaft, individually, to the conditions of the patient.
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Besides shaft size and head size, still further strongly patient-dependent, as a rule, is the so-called CCD-angle that the shaft axis forms with the shank neck axis running through the head center point and the adjacent shank neck, and crossing the shaft axis. This CCD-angle in the case of the natural femur on the average lies at approximately 126.degree., with a width of variation between 115.degree. and 140.degree.. In the case of the two-piece hip joint acetabular prosthesis in accordance with the German Laid Open Print 27 34 249, the CCD-angle is obtained by approximate curving of the single-piece connecting part formed at the head; the selection of a suitable CCD-angle and the selection of a required head size that is independent thereof is, therefore, not possible in the case of this known hip joint femoral prosthesis. A somewhat sufficient adaptation of CCD-angle and head size to the patient data, much more to the point, can, in the case of this known hip joint femoral prosthesis, only be realized by maintaining in stock (inventory) for each head size a plurality of head parts with different CCD-angles. Therefore, the operator must, e.g. during an operation, select from a large number of different head parts the one displaying the correct head size and, additionally, the correct CCD-angle.
Particularly preferred, the conical boring in the proximal end of the shaft runs at a predetermined angle of .alpha.(alpha)<180.degree. to the shaft axis, with the conical boring then being made in a region of the shaft that retains about the conical boring the greatest possible wall thickness and, therewith, the greatest possible wall strength. With this form of embodiment of the invention, the CCD-angle is obtained by the difference between the angle and .beta. (beta). Particularly preferred, the conical boring of the shaft runs at an angle .alpha..apprxeq.140.degree. (alpha approximately equal) to the shaft axis, and the angle .beta. (beta) between the two socket cones of the connecting part then lies, for realizing a CCD-angle of 140.degree. to 110.degree., in the region of 0.ltoreq..beta..ltoreq.30.degree. (zero is less than or equal to beta and beta is less than or equal to 30.degree.).
The hip joint femoral prosthesis 1 represented in FIG. 1 has a shaft 2, the distal end of which is broken away and whose proximal end has a surrounding collar 4 and a neck section 6 formed on the collar 4. Worked into the shaft 2, from the shaft side neck section 6, is a conical boring 8 whose axis 23 coincides with the axis of the neck section 6, and which, with the shaft axis 3, includes an angle .alpha. (alpha).
Inserted, while forming a firm frictional connection, into the conical boring 8 at the proximal end of the shaft 2 is a first socket cone 22 that is disposed on the shaft side end of a connecting part 20. Adjoining at the socket cone 22 of the connection part 20 is a center section 26 and, thereupon, a second socket cone 24 that represents the head side end of the connecting part 20 and that is capable of being anchored in a conical boring 32 in the head 30. The center section 26, together with the neck section 6 of the shaft 2, represents the hip joint femoral prosthesis and is constructed essentially cylindrically. Axis 25 running through the second socket cone 24 and the center point of the head 30 intersects with axis 23 of the first socket cone 22 and, with this axis 23, includes an angle .beta. (beta) lying approximately between 0.degree. and 50.degree.. The first socket cone 22 is capable of being inserted into and anchored in conical boring 8 in the shaft 2 at any angular position relative to shaft 2 so that the shaft 2 through the connecting part 20 to the head 30 can undergo two angular deflections.
CCD-angle=.alpha.-.beta. (alpha minus beta)
In the form of embodiment represented, the angle .alpha. (alpha) between shaft axis 3 and axis 23 of the conical boring 8 comes to about 140.degree., the angle .beta. (beta) between the longitudinal axes 23 and 25 of the two socket cones 22 and 24 comes to about 25.degree., the CCD-angle between the conical axis 25 and the shaft axis 3 comes then to about 115.degree..
Represented in FIG. 2 are different connecting parts 20 having a different angle .beta. (beta) between the longitudinal axes 23, 25 of the socket cones 22, 24. The connecting part in accordance with FIG. 2a has an angle .beta. (beta)=0, the head then sits aligned straight over the socket cone 22, the CCD-angle is identical with angle .alpha. (alpha) and then comes to about 140.degree. in the case of the shaft represented.
Represented in FIG. 2b and 2c are connecting parts 20 whose angles .beta. (beta) between the longitudinal axes 23, 25 of the socket cones 22, 24 come to 5.degree., respectively 25.degree..
1. Hip joint femoral prosthesis comprising a shaft, a spherical head and a connecting part between the shaft and the head, with a conical boring at the proximal end of the shaft and a corresponding first socket cone on the shaft end of the connection part, and wherein the connecting part displays on the head end a second socket cone, wherein said first socket cone is capable of being inserted into and anchored in a conical boring in the shaft at any angular position relative to said shaft, and that the longitudinal axis of the first socket cone and the longitudinal axis of the second socket cone intersect at a predetermined angle 0.degree..ltoreq..beta..ltoreq.50.degree. (zero is less than or equal to beta and beta is less than or equal to 50.degree.) so that from the shaft through the connecting part to the head may undergo two angular deflections.
4. Hip joint femoral prosthesis according to claim 1, wherein the conical boring of the shaft runs at a predetermined angle.alpha.<180.degree. (alpha is less than 180.degree.) to the shaft axis.
5. Hip joint acetabular prosthesis according to claim 4, characterized by the fact that the angle.alpha. (alpha) is about 140.degree..
2646842 April 1978 DEX
2734249 February 1979 DEX
3340767 May 1985 DEX
2580926 October 1986 FRX
Patent number: 4822370
Assignee: Orthoplant Endoprothetik (Bremen)
Inventor: Klaus-Dieter Schelhas (Bremem)
Application Number: 7/210,200