Source: https://patents.justia.com/patent/7121755
Timestamp: 2020-02-25 16:52:07
Document Index: 160285772

Matched Legal Cases: ['art 2', 'art 25', 'art 25', 'art 25', 'art 25', 'art 25', 'art 25', 'art 25', 'art.\n5', 'art.\n8']

US Patent for Device for a ball-and-socket joint type connection of two members Patent (Patent # 7,121,755 issued October 17, 2006) - Justia Patents Search
Justia Patents With Threaded JointUS Patent for Device for a ball-and-socket joint type connection of two members Patent (Patent # 7,121,755)
Device for a ball-and-socket joint type connection of two members
Jun 30, 2004 - Synthes (U.S.A.)
A device for a ball-and-socket-type connection of two members includes a first member having a head and a second member having a cavity that receives the head. The cross-sectional surface of the cavity is tapered at the lower end of the second member as a result of a constriction. The head and/or cavity is configured spherically with a center of articulation (Z). The ball-and-socket-type connection between the two members can be detachably fixed by a clamping element that can be connected to the second member. The head has a recess in which the front end of the clamping element can rest. The recess and/or the front end has an at least partially spherical surface with a centre (C). In the clamped position of the device, the center of articulation (Z) and the centre (C) are identical.
This application is a continuation of pending application PCT/CH01/00744 filed Dec. 31, 2001.
The invention relates to a device for the ball-and-socket joint type connection of two parts.
A stabilization device that interconnects the bone-fixation means, such as pedicle screws, with a longitudinal member, such as a longitudinal spinal rod, extending along at least a portion of a patient's spinal column, is used, for example, for the internal stabilization of the spinal column. In order to securely stabilize the spinal column, it should be possible to connect the bone-fixation means, on the one hand, firmly with the vertebrae and, on the other, with the longitudinal member. Preferably, the head of the bone fixation means and the longitudinal member are connected by a connecting mechanism, which permits the longitudinal member to be fixed with respect to the bone-fixation means at a variety of different angles. Moreover, the connecting mechanism may be detachable, so that the mechanism may be later removed without large openings being formed in the tissue of the spinal column region.
Such a connection mechanism between a bone-fixation means and a longitudinal member for the internal stabilization of a vertebrae is known, for example, in U.S. Pat. No. 5,466,237 to Byrd which discloses a bone-fixation screw having a screw head, which is constructed with a spherical shaped lower surface and a convexly shaped upper surface. The spherical shaped lower surface is mounted in a borehole formed in the connecting mechanism, this borehole comprising a concave section, which tapers towards the screw shaft, as a result of which, and together with the screw head, a ball-and-socket type joint connection is established between the bone-fixation screw and the connecting mechanism. This connection is locked by tightening a nut, which can be screwed over an external thread formed on the upper portion of the connecting mechanism. Tightening the nut, forces the nut against the longitudinal member, which is placed in a transverse channel formed in the connecting mechanism for this purpose. The longitudinal member thereafter presses on the convexly-shaped upper surface of the boKne-fixation screw, so that, as the nut is tightened, the longitudinal member and the bone-fixation screw are locked in the connecting mechanism.
The present invention addresses these problems and others by providing a device, which comprises a spherically shaped connection between two members, the mechanism comprising clamping means, the front end of which contacts the surface of a depression formed in the joint head of the bone-fixation means, as a result of which a smaller overall height of the connection mechanism is possible, and which, in the unlocked state, permits polyaxially angular positioning of the central axes of the two parts relative to each other.
due the coincidence of the center of the joint and of the center of the spherically shaped contact surface at the front end of the clamping means and/or of the depression at the joint head, locking of the two members with respect to one another at different angles of the central axes of the two members becomes possible without the occurrence of levering forces associated with the prior art; and
because the joint head is fixed in the cavity by the clamping means, the front end of which can be brought into contact with a depression at the joint head, the latter can be configured lower, as a result of which the device has smaller dimensions.
As will be described herein, the clamping means in various, different embodiments can be configured differently at their front end, depending on the desired form of contact with the depression, for example:
by configuring the front end of the clamping means as a point, which is concentric with the central axis, a punctiform contact between the front end and the depression can be achieved;
by configuring the front end of the clamping means as a flattened surface, orthogonally to the central axis, linear contact between the front end and the depression can be attained and
by configuring the front end of the clamping means spherically, a contact surface can be established between the front end and the depression.
In further embodiments, the depression formed in the joint head of the bone-fixation means may be spherical or conical, as a result of which, by pairing clamping means with a spherically formed front end, a contact surface or a linear contact can be attained between the front end of the clamping means and the depression.
a) a first member which is sized and configured as a bone-fixation means, for example, as a pedicle screw, a pedicle hook, etc., the lower segment of which is used to fix the bone-fixation means to a patient's bone; and
b) a second member which is sized and configured as a connecting mechanism and/or part for interconnecting the longitudinal member, for example, a longitudinal spinal rod, with the bone-fixation means. The second member may further include a channel, disposed transversely to the central axis, for accommodating the longitudinal member and a central borehole with internally formed threads, disposed coaxially with the central axes.
Furthermore, the device may include mounting means for fixing the longitudinal member, inserted into the transverse channel, so that the device can be used, for example, as a spinal fixation device.
FIG. 2a shows a section of the clamping means of an embodiment of the inventive device,
FIG. 2b shows a section of the clamping means of a different embodiment of the inventive device,
FIG. 4a shows a section through the joint head of an embodiment of the inventive device,
FIG. 4b shows a section through the joint head of a different embodiment of the inventive device,
The second part 2 may also have a central axis 6, an upper end 21, a lower end 22, an upper segment 23 and a cavity 4, which is disposed at the lower end 22 and forms the second joint segment 20. The cavity 4 may be disposed coaxially with the central axis 6 and is tapered at the lower end 22 of the second member 2 by a constriction 14 formed on the lower end 22. Preferably, the constriction 14 has a spherical shaped support 37 forming a center which coincides with the joint center Z. The spherically shaped support 37 being directed towards the interior of the cavity 4. Preferably, the spherically shaped support 37 is complementary with the surface of the joint head 3, so that the two joint segments 10; 20 can be rotated with respect to one another about three mutually perpendicular axes.
As shown, in FIGS. 2a and 2b , in each case showing different embodiments of the clamping means 7, the front end 16 of the clamping means 7, as shown in FIG. 2a, may have a point which is coaxial with the central axis 6, whereas, as shown in FIG. 2b, the front end 16 of the clamping means 7 is shown as being convexly spherical.
As shown in FIG. 4a, the joint head 3 differs from the embodiments described above only in that the depression 8 at the upper end 11 of the first member 1 has a conical, coaxial section 40 and an axially adjoining circular cylindrical section 41 with the diameter D at a depth T, measured from the upper end 11. The diameter D is selected so that the depression 8 is constricted at the depth T by the circular cylindrical section 41, so that a circular edge 39, concentric with the central axis 6, is formed by the transition between the conical section 4 and the circular cylindrical section 41. Furthermore, the diameter D and the depth T are dimensioned so that the circular edge 39 coincides on an imaginary spherical surface with the center C, lying on the central axis 6, and with the radius R, as was the case with the embodiment depicted in FIG. 3.
As shown in FIG. 4b, the joint head 3 may have a conical depression 8 forming a cone 42. The diameter of the cone 42 at the upper end 11 of the first member 1 and the conical angle of the cone 42 are dimensioned so that the cone 42 touches an imaginary spherical surface with the center C, lying on the central axis 6, and with a radius R, as was the case with the embodiment depicted in FIG. 3.
A linear contact between the clamping means 7 and the depression 8 can be achieved by a configuration of the depression 8 and of the front end 16 of the clamping means 7 of one of the FIG. 3, 4a or 4b.
As shown, in FIGS. 5–7 and 10, an alternate embodiment of the present device is shown wherein the device comprises, a first member 1 having bone fixation means 24, which as shown is a pedicle screw, but which may also be a pedicle hook, etc., and a second member 2 having a connecting part 25 for connecting a longitudinal spinal member 26 to the bone fixation means 24. As partially shown, the bone fixation means 24 may include a lower threaded shaft segment 13 and a joint screw head 3. The lower surface side of the screw head, i.e., on the side facing the screw shaft, the screw head is preferably constructed with a partially spherically surface having a radius R2, the center of the spherical lower surface, preferably lying on the central axis 6, forming the joint center Z.
As shown in FIG. 8, the device differs from the embodiment, shown in FIGS. 1 and 3, only in that the second member 2, may include a channel 27 formed in the connecting part 25 for accommodating a longitudinal member, the channel 27 being open at the upper end 21 of the connection part 25. The clamping means 7 may be screwed coaxially along the central axis 6 against the internal threads 31 formed in the central borehole 30 of the connecting part 25, so that the front end 16 of the clamping means 7 can be pressed against the surface 9 of the depression 8 at the upper end 11 of the first member 1. When the device is installed, the clamping means 7 is thus disposed between the longitudinal member 26, placed in the channel 27, and the cavity 4 in the second member 2. The longitudinal member 26 being locked in the channel 27 by mounting means 29, which is shown as an externally threaded setscrew and which, after the longitudinal member 26 is placed in the channel 27, can be screwed from the upper end 21 of the connecting part 25 into engagement with the internal threads 52. The internal thread 52 and the internal thread 31, both of which are disposed coaxially with the central axis 6 in the central borehole 30, can also be formed as a single internal thread.
As shown in FIG. 9, the device differs from the embodiment shown in FIG. 8 only in that the internal thread 52 formed in the central borehole 30 extends only so far from the upper end 21 of the connecting part 25, so that a longitudinal member 26, placed in the channel 27, can be locked in the channel 27 by means of the mounting means 29. As shown, the central borehole 30 is configured circularly cylindrically between the longitudinal section of the central borehole 30, which is provided with the internal thread 52, and the cavity 4, so that the clamping means 7 can be moved parallel to the central axis 6 in the central borehole 30. At its rear end 17, the clamping means 7 may include a notch 51, which extends transversely to the central axis 6. In the installed device, the longitudinal member 26, placed in the channel 27, rests in the notch 5 1, so that, when the mounting means 29 is tightened, it presses against the longitudinal member 26, which, in turn, presses on the clamping means 7. The clamping means 7 thereafter being moved parallel to the central axis 6 against the front end, 22 of the connecting part 25 thereby pressing with its front end 16 onto the surface 9 of the depression 8 at the upper end 11 of the first member 1. Thus, tightening the mounting means 29, locks the longitudinal member 26 and the first member 1 simultaneously in the device.
1. A device forming a ball-and-socket joint connection of two parts, comprising:
a first member and a second member, which are connected with one another in the form of a ball-and-socket joint;
the first member having a central axis, a first joint segment with an upper end, and a lower segment;
the second member having a central axis, a second joint segment with a lower end, and an upper segment with an upper end;
the first joint segment being configured as a joint head having a depression at the upper end whereas the second joint segment is configured as a cavity, which accommodates the joint head, the cavity being concentric with the central axis of the second member and having an opening for the passage of the lower segment of the first member therethrough;
wherein the cavity further includes a constriction formed by a tapered surface formed in the lower end of the second member; the constriction having a support for the joint head, which is directed towards the interior of the cavity;
wherein at least one of the joint segments in the contact region of the joint segments is configured spherically with a joint center (Z);
wherein the joint connection between the two joint segments is fixable by clamping means, the clamping means including a front end sized and configured to contact the depression formed in the first joint segment and including a rear end, the clamping means connectable with the second joint segment;
wherein at least one of the depression and the front end of the clamping means includes a partially spherical surface, which has a center (C) characterized in that the joint center (Z) and the center (C) of the clamping means are identical when the device is locked together.
wherein the second member is a connecting part for connecting a longitudinal member with the first member, the connecting part including a channel sized and configured to accommodate the longitudinal member, the channel further including a channel axis which is disposed transversely to the central axis of the second member;
wherein the channel axis is displaced laterally with respect to the central axis of the second member such that the clamping means does not protrude into the channel;
wherein the clamping means is operative to lock the first and second members to one another independent of locking the longitudinal member; and
wherein the device further comprises a covering cap having a tab parallel to the central axis of the second member, the covering cap being sized and configured to slidably engage the connecting part; wherein the covering cap is fixed with respect to the connecting part by mounting means.
2. The device of claim 1, wherein the second member further comprises a central borehole, which is disposed coaxially with the central axis of the second member.
3. The device of claim 2, further comprising mounting means for securing the longitudinal member into the channel.
4. The device of claim 2, wherein the central borehole has an internal thread and the clamping means is a clamping screw, which is sized and configured to threadedly engage the internal thread formed in the connecting part.
5. The device of claim 1, wherein the channel is opened toward the side of the connecting part and has a lateral channel opening, which is disposed transversely to the central axis of the second member and transversely to the channel axis.
6. The device of claim 1, wherein, when the covering cap is installed, the tab is sized and configured to laterally surround at least a portion of the longitudinal member so that the longitudinal member is fixed in the channel by the mounting means.
7. The device of claim 1, wherein the channel is opened towards the upper end of the connecting part.
8. The device of claim 7, wherein the second member further comprises a central borehole and the clamping means is axially movable in the central borehole.
9. The device of claim 8, wherein the central borehole has an internal thread and the clamping means has an external thread, the internal thread being sufficiently long, so that the clamping means can be brought into contact with the first member.
10. The device of claim 1, wherein the connecting part has an external thread at its upper end and that the mounting means is a nut having an internal thread sized and configured to threadably engage the external threads so that the covering cap via the mounting means can be brought into contact with the longitudinal member inserted in the channel.
11. The device of one of the claim 1, wherein the front end of the clamping means has a tip, which is concentric with the central axis of the second member.
12. The device of claim 1, wherein the front end of the clamping means has a flat surface, which is orthogonal to the central axis of the second member.
13. The device of one of the claim 1, wherein the front end of the clamping means has a spherical configuration.
14. The device of claim 13, wherein the front end of the clamping means is spherical with the center (C) of the clamping means and has a radius (R).
15. The device of one of the claim 14, wherein the depression is spherical with the center (C) of the clamping means.
16. The device of claim 14, wherein the depression is configured as a cone having a diameter and a conical angle, the diameter of the cone at the upper end of the first part and the conical angle being dimensioned so that the cone touches an imaginary spherical surface having the center (C) of the clamping means and a radius (R).
17. The device of claim 14, wherein the depression has a circular edge, which is concentric with the central axis of the first member, the circular edge resting on an imaginary spherical surface having the center (C) of the clamping means and a radius (R).
18. The device of claim 1, wherein the joint head is rigid so that, when the device is locked, movement of the joint head is not possible.
19. The device of claim 1, wherein the at least one spherical surface of the device has a roughened surface.
20. The device of claim 1, wherein at least one of the members of the device, which is provided with a spherical surface, is softer, at least in the contact region, than the other member of the device.
21. The device of claim 1, wherein the first member comprises bone fixation means, so that the lower segment secures the device to a bone.
22. The device of claim 1, wherein the channel axis is offset laterally and longitudinally from the joint center (Z).
23. The device of claim 1, wherein the first joint segment has two flat perimeter sides opposite each other that enable the first member to be inserted into the second member through the opening of the cavity from the lower end of the second member.
6540748 April 1, 2003 Lombardo
2810533 December 2001 FR
WO 01/22893 April 2001 WO
Patent number: 7121755
Patent Publication Number: 20050033436
Assignee: Synthes (U.S.A.) (West Chester, PA)
Inventors: Fridolin Schlapfer (Glarus), Renzo Defranceschi (Ramlinsburg)
Assistant Examiner: Michael P. Ferguson
Application Number: 10/881,166
Current U.S. Class: With Threaded Joint (403/77); Articulate Joint Is Ball And Socket (403/76); Ball And Socket (403/90); Including Internal Tie Means (403/123); Rod Received In Open Channel (403/399); 606/61; Spine Bone (623/17.11); Having Ball And Socket Means (623/17.14)