GB2410289A

GB2410289A - Lockable clamp

Info

Publication number: GB2410289A
Application number: GB0401186A
Authority: GB
Inventors: Grahame David Bannister; Peter James Briggs
Original assignee: Eschmann Holdings Ltd
Current assignee: Eschmann Holdings Ltd
Priority date: 2004-01-20
Filing date: 2004-01-20
Publication date: 2005-07-27
Anticipated expiration: 2024-01-20
Also published as: GB0401186D0; GB2410289B

Abstract

A clamp which comprises a mounting element 102 having a ball 108 at one end and a clamp housing 112 which encloses the ball 108 and allows its rotation therein. The clamp housing 112 further containing two opposed through holes defining a pathway 115 for receiving an elongate bar 106. The clamp further comprising a locking member 116, having a wedge shape, disposed within the housing 112 and having a concave first surface 118 for mating with the ball 108 and a second surface 128 for mating with the elongate bar 106. The housing also having a threaded aperture 138 for receiving a threaded member 40, whose end portion 142 abuts the locking member 116, and is operable to drive the wedge part between the ball 108 and the elongate bar 106, the pathway 115 of the elongate bar being laterally spaced from the rotational axis of the threaded member 140. The clamp may be used for attaching an accessory to a surgical table.

Description

241 0289 LOCKABLE CLA1\IP The present invention relates to a lockable

clamp, in particular a lockable clamp adapted to mount an accessory to a surgical table in a selected orientation.

It is well known to provide surgical tables with venous types of accessory which are intended to be removably fitted to the table dependent on the needs of the surgeon and the patient. Such accessories typically comprise arm or leg supports which extend outwardly from the table surface for supporting the limbs of a patient during a surgical procedure.

Other types of accessory are also known. Such accessories need to be removably fitted to the surgical table, and also orientable into a number of different positions, dependent on the requirements of the particular patient.

Various types of clamp are known for locking the accessory in the selected orientation.

The clamp is required to lock the position of the accessory in such a manner that the accessory does not inadvertently move from that position during the surgical procedure.

Some clamps are required to lock both the translational and rotational positions of the accessory. This locking should ideally be achieved without requiring the medical personnel to use high manual forces when locking the clamp in a particular configuration.

The clamp for the accessory should exhibit versatility to enable a variety of different accessories to be fitted in a wide variety of different configurations. Furthermore, the clamp should be of a construction to permit a variety of different styles and types of rigid fixtures to be fitted to the clamp.

Known clamp assemblies are disclosed in US-A-6058534 (Locking-cylinder supported surgical boot), US-A-5940912 (Surgical armboard), US-A-5802641 (Leg holder system for simultaneously positioning in the abduction and lithotomy dimensions), US-A- 4898491 (Locking pivot assembly with both pivot and tilt axes), US-A- 4698837 (Armboard mounting assembly), WO-A-02/41822 (Accessory support for a patient resting surface), EP-A-0803239 (Leg holder device), and others. Many of these known clamp assemblies suffer from the problem of a lack of versatility, for co-operation with a variety of different surgical table accessories for selectively disposing the accessories in a variety of different configurations. Most particularly, some known clamp assemblies are rather clumsy or difficult for medical personnel to operate in the operating theatre.

Figures 5 and 6 illustrate an example of a particular known clamp assembly for surgical

tables.

The external structure of the known clamp assembly is shown in Figure S. The known ball locking clamp assembly comprises a mounting element 2, for mounting on a surgical table (not shown) and a clamp 4 fitted to the mounting element 2. The clamp 4 supports an accessory bar 6 to which is attached an accessory (not shown) such as a limb support. The mounting element 2 is provided at one end with a spherical ball 8 which fits in the clamp 4 on an annular part- spherical seat l O. The ball 8 is captive in a housing 12 of the clamp 4.

The ball 8, can, when the clamp 4 is unlocked, be rotated on the seat 10 so that the clamp 4 can be disposed in a selected angular orientation with respect to the mounting element 2.

The accessory bar 6 extends through the housing 12 of the clamp 4 between two opposed through-holes 14 in the housing 12. When the clamp 4 is unlocked, the accessory bar 6 can be slid translationally relative to the clamp 4. In this way, when the clamp 4 is unlocked, the accessory mounted on the remote end (not shown) of the accessory bar 6 can be disposed in a selected rotational and translational position with respect to a surgical

table.

The known clamp 4 is permanently attached to the respective accessory bar 6, for example by the clamp 4 being held captive on the accessory bar 6 by the provision of an enlarged end 49 on the accessory bar 6, typically a plastic knob, as shown in Figure S. When the clamp 4 is locked, the clamp 4 is rotationally locked relative to the mounting element 2 and the accessory bar 6 is translationally locked relative to the clamp 4. The locking and unlocking of the clamp 4 is achieved by rotation, in the respective angular direction, of a handle 44 fitted to the clamp 4. The operation of the handle 44 commonly locks and unlocks both the clamp 4 to the mounting element 2 and the accessory bar 6 to the clamp 4.

The internal structure of the known clamp assembly is shown in Figure 6. The ball 8 of the mounting element 2 is received in the annular cylindrical outer housing 12 of the clamp 4 which defines the annular part-spherical seat 10 for the ball 8. The seat 10 is located on the same side of the centre of the ball 8 as that of the mounting element 2 whereby the ball 8 is held captive by the seat 10 within the outer housing 12 of the clamp 4. The pair of opposed through-holes 14 are provided on opposite sides of the outer housing 12 through which the accessory bar 6 extends in a direction orthogonal to the axis of the outer housing 12.

An inner floating block 16 is disposed between the ball 8 and the accessory bar 6. The mner floating block 16 includes, on one side thereof; a part-spherical concave surface 18 mating with the spherical convex surface 20 of the ball 8, and, on the other side thereof, a concave surface 22 shaped to engage the convex outer cylindrical surface 24 of the accessory bar 6. The concave surface 22 has a width, in a direction orthogonal to the axis of the accessory bar 6, which is greater than the diameter of the accessory bar 6. The concave surface 22 includes a partcylindrical end portion 26, a central substantially planar ramp portion 28, and a curved end portion 30. The ramp portion 28 extends tangentially away from the cylindrical surface 24 of the accessory bar 6. A wedge portion 32 of the mner floating block 16 is defined between the ramp portion 28 and the part-spherical concave surface 18. The inner floating block 16 includes an extending part 34, on one side of which the ramp portion 28 and the curved end portion 30 are provided and on the other side of which an urging face 36 is provided.

A threaded hole 38 is provided in the outer housing 12 and a threaded bolt 40 extends through the threaded hole 38 whereby one end 42 of the bolt 40 is disposed against the urging face 36 of the extending part 34 of the inner floating block 16. A manually operable handle 44 is provided at the other end 46 of the threaded bolt 40.

When it is desired to lock the accessory m the selected rotational and translational orientation relative to the surgical table, the accessory bar 6 is translationally slid to the desired translational position relative to the clamp 4 and the clamp 4 is angularly rotated to a desired rotational configuration relative to the mounting element 2. The threaded bolt 40 is then rotated, by rotating the handle 44, so as to be screwed into the threaded hole 38 and urged against the urging face 36 of the extending part 34. This causes the inner floating block 16 to be pushed by the threaded bolt 40 inwardly relative to the housing 12 and towards the accessory bar 6 and the ball 8 so that the inner floating block 16 frictionally engages both the accessory bar 6 and the ball 8. In the orientation shown in Figure 6, the inner floating block 16 is pushed in an upwardly direction. Progressive movement of the inner floating block 16 in this direction causes the accessory bar 6 to be progressively slid along the ramp portion 26 and the wedge portion 32 to be urged between the accessory bar 6 and the ball 8. This tends to urge the inner floating block 16 in a direction towards the ball 8, which is towards the left direction in the configuration shown in Figure 6. The ball 8 is urged against the seat 10, thereby locking the rotational position of the ball 8. The accessory bar 6 is urged against the edges of the through-holes 14 in the annular wall of the housing 12, thereby locking the translational position of the accessory bar 6.

In this way, the inner floating block 16 is moved by the operation of the handle 44 until it securely frictionally engages both the accessory bar 6 and the ball 8 to push each into a locked position. The clamp 4 is thereby locked. The inner floating block 16 acts as a wedge between the ball 8 and the accessory bar 6, thereby locking both using a common clamping action. The clamp 4 is unlocked by rotating the handle 44 in the opposite direction so as to release the end 42 of the bolt 40 from exerting pressure on the urging face 36 of the inner floating block 16.

The handle 44 is pivotally fitted to the threaded bolt 40 via a pin member 48, orthogonal to the threaded bolt 40, in such a way as to ensure a tight friction fit between the handle 44 and the threaded bolt 40. In this way, the handle 44 can be maintained in a compact (parked) position, substantially adjacent to the clamp 4, as shown in Figure 6. Such a configuration is employed to prevent the handle inadvertently sticking out unnecessarily, which could be inconvenient or hazardous.

The present invention aims to provide an improved ball-locking clamp assembly.

Accordingly, the present invention provides a clamp for mounting an accessory to a surgical table, the clamp comprising a mounting element for mounting the clamp to a surgical table, the mounting element having a ball, a clamp housing which at least partially contains the ball and includes an annular seat for the ball, the ball being selectively rotatable in the seat, the clamp housing having two opposed through-holes therein which define therebetween a pathway through the clamp housing for, in use, receiving an elongate bar of an accessory for a surgical table, a locking member disposed in the clamp housing, the locking member having a concave first surface for mating with an outer surface of the ball and a second surface adjacent to the pathway for mating with an outer surface of an elongate bar extending along the pathway, the first surface and the second surface defining therebetween a wedge portion, a threaded opening in the clamp housing, a threaded member extending through the threaded opening into the clamp housing and engaging an urging face of the locking member, the threaded member having a rotational axis, wherein the pathway is laterally spaced from the rotational axis of the threaded member.

Preferably, the pathway is located between the ball and the rotational axis of the threaded member.

Preferably, the locking member has a cavity extending therethrough, the cavity partially defining the pathway for receiving the elongate bar, and an inner surface of the cavity comprising the second surface.

More, preferably, the cavity is substantially oval.

Preferably, the second surface is a ramp surface inclined at an acute angle to the rotational axis of the threaded member.

The clamp preferably further comprises a biasing member for biasing the urging face of the locking member against the threaded member. The biasing member may comprise a compression spring.

The clamp preferably further comprises a rotation preventing device for preventing rotation of the locking member in the housing. The rotation preventing device may comprise a recess in the locking member receiving an end of the threaded member, the recess including the urging face.

Preferably, the clamp further comprises a manually operable elongate handle mounted on the threaded member, the handle having a leaf spring for biasing the handle at least to a position orthogonal to the rotational axis of the threaded member. The leaf spring may have an outer surface which is biased against an outer cylindrical surface of the threaded member. Preferably, the leaf spring and the handle are integrally moulded.

Preferably, the clamp further comprises at least one accessory for a surgical table, the accessory being mounted on an accessory bar, the accessory bar extending through the clamp housing along the pathway. More preferably, the accessory bar is selectively removable from the clamp, when unclamped, by sliding the accessory bar out of the clamp housing along the pathway.

The present invention also provides the combination of a clamp according to the present invention claim and a plurality of accessory bars therefor, each accessory bar having mounted thereon a respective accessory for a surgical table, and each accessory bar being selectively locatable so as to extend through the clamp housing along the pathway.

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure I is a perspective view of a clamp in accordance with a first embodiment of the present invention; Figure 2 is a perspective view of the clamp of Figure 1 fitted with an accessory for a

surgical table;

Figure 3 is an enlarged perspective view of the assembly of the clamp and accessory of Figure 2; Figure 4 Is a schematic sectional view through the clamp and accessory shown in Figures 1 to3; Figure 5 is a perspective view of a known clamp assembled with a captive accessory bar; and Figure 6 is a sectional view of the known clamp and captive accessory bar of Figure 5.

Referring to Figures 1 to 4, these figures show a surgical accessory clamp, in the form of a ball-locking clamp assembly, in accordance with an embodiment of the present invention.

The external structure of the clamp assembly of the embodiment of the present invention is shown in Figure 1, and Figures 2 and 3 show the clamp assembly of Figure 1 in combination with an accessory bar assembled therewith. The ball locking clamp assembly, designated generally as 100, comprises a mounting element 102, for mounting on a surgical table (not shown) and a clamp 104 fitted to the mounting element 102. The clamp 104, in use, supports an accessory bar 106 to which is attached an accessory 107, such as a limb support. The mounting element 102 is provided at one end with a spherical ball 108 which fits in the clamp 104 on an annular part-spherical seat 110. The ball 108 is captive in a housing 112 of the clamp 104. The ball 108, can, when the clamp 104 is unlocked, be rotated on the seat 110 so that the clamp 104 can be disposed in a selected angular orientation with respect to the mounting element 102. The accessory bar 106 extends through the housing 112 of the clamp 104 between two opposed through-holes 114 in the housing 112. When the clamp 104 is unlocked, the accessory bar 106 can be slid translationally relative to the clamp 104. In this way, when the clamp 104 is unlocked, the accessory 107 mounted on the remote end of the accessory bar 106 can be disposed in a selected rotational and translational position with respect to a surgical table.

When the clamp 104 is locked, the clamp 104 is rotationally locked relative to the mounting element 102 and the accessory bar 106 is translationally locked relative to the clamp 104. The locking and unlocking of the clamp 104 is achieved by rotation, in the respective angular direction, of a handle 144 fitted to the clamp 104. The operation of the handle 144 commonly locks and unlocks both the clamp 104 to the mounting element 102 and the accessory bar 106 to the clamp 104.

The internal structure of the clamp assembly of the embodiment of the present invention is shown in Figure 4. The ball 108 of the mounting element 102 is received in the annular cylindrical outer housing 112 of the clamp 104 which defines the annular part-spherical seat 110 for the ball 108. The seat 110 is located on the same side of the centre of the ball 108 as that of the mounting element 102 whereby the ball 108 is held captive by the seat within the outer housing! 12 of the clamp 104. The pair of opposed through-holes 114 are provided on opposite sides of the outer housing 112 through which the accessory bar 106 extends along a pathway 115 m a direction orthogonal to the axis of the outer housing 112.

An inner floating block 116 is disposed in the housing 112 and includes a central portion 117 between the balllO8 and the pathway 115, the pathway 115 including the accessory bar 106 when the latter is assembled in the clamp 104. The inner floating block 116 has a cavity 119 extending therethrough, the cavity 119 partially defining the pathway 115 for receiving the accessory bar 106. The inner floating block 116 includes, on one side thereof, a part-spherical concave surface 118 mating with the spherical convex surface 120 of the ball 108, and, on the other side thereof, an inner surface 122 of the cavity 119 shaped to engage the convex outer cylindrical surface 124 of the accessory bar 106. The cavity 119 is substantially oval and has a major axis inclined at an acute angle to a direction orthogonal to the axis of the housing 112. The cavity 119 has a width along its major axis, in a direction orthogonal to the axis of the accessory bar 106, which is greater than the diameter of the accessory bar 106. The cavity 119 includes a part-cylindrical first end portion 126, a central substantially planar ramp portion 128, and a part-cylindrical second end portion 130. The ramp portion 128 extends tangentially away from the cylindrical surface 124 of the accessory bar 106. A wedge portion 132 of the inner floating block 116 is defined between the ramp portion 128 and the part-spherical concave surface 118, so as in use to be located between the ball 108 and the accessory bar 106.

The inner floating block 116 includes an extending part 134 on a side of the cavity 119 remote from the wedge portion 132. On a side of the extending part 134 an urging face 136 is provided. 8. The urging face 136 is disposed in a recess 137, comprising an axially directed groove, in the inner floating block 116.

A threaded hole 138 is provided in the outer housing 112 and a threaded bolt 140 extends through the threaded hole 138 whereby one end 142 of the bolt 140 Is disposed against the urging face 136 of the extending part 134 of the inner floating block 116. The cavity 119 defining the pathway 115 which, in use, receives the accessory bar 106 is laterally spaced from the rotational axis of the threaded bolt 140. The ramp portion 128 is inclined at an acute angle to the rotational axis of the threaded bolt 140. The reception of the end 142 of the bolt 140 in the groove 137 prevents rotation of the inner floating block 116 in the housing 112. A manually operable handle 144 is provided at the other end 146 of the threaded bolt 140, pivotally mounted thereto by a pin member 151. The manually operable handle 144 is elongate. The handle 144 has an integrally moulded leaf spring for biasing the elongate handle at least to a position orthogonal to the rotational axis of the threaded bolt 140. The leaf spring 145 has an outer surface 147 which is biased against an outer cylindrical surface 149 of the threaded bolt 140.

A biasing member 139, which comprises a compression spring, has opposed ends respectively disposed in recesses 161, 163 in the inner wall of the housing 112 and in the inner floating block 116. The compression spring 139 is coaxial with the threaded bolt 140. The compression spring 139 acts to bias the urging face 136 of the inner floating block 116 against the end 142 of the threaded bolt 140. This ensures that the accessory bar 106 can be readily passed through the cavity 119 when the accessory bar 106 is assembled together with the clamp 104.

A cover member 165 is fitted into the end of the housing 112 remote from the ball 108 so as to inhibit or prevent bacteria or infection from entering the housing 112.

When it is desired to lock the accessory in the selected rotational and translational onentahon relative to the surgical table, the accessory bar 106 is translationally slid to the desired translational position relative to the clamp 104 and the clamp 104 is angularly rotated to a desired rotational configuration relative to the mounting element 102. The threaded bolt 140 is then rotated, by rotating the handle 144, so as to be screwed into the threaded hole 138 and urged against the urging face 136 of the extending part 134. This causes the inner floating block 116 to be pushed by the threaded bolt 140 inwardly relative to the housing 112 and towards the accessory bar 106 and the ball 108 so that the inner floating block 166 frictionally engages both the accessory bar 106 and the ball 108. In the orientation shown in Figure 4, the inner floating block 116 is pushed in an upwardly direction. Progressive movement of the inner floating block 116 in this direction causes the accessory bar 106 to be progressively slid along the ramp portion 126 and the wedge portion 132 to be urged between the accessory bar 106 and the ball 108. This tends to urge the inner floating block 116 in a direction towards the ball 108, which is towards the left direction in the configuration shown in Figure 4. The ball 108 is urged against the seat 110, thereby locking the rotational position of the ball 108. The accessory bar 106 is urged against the edges of the through-holes 114 in the annular wall of the housing 112, thereby locking the translational position of the accessory bar 106.

In this way, the inner floating block 116 is moved by the operation of the handle 144 until it securely frictionally engages both the accessory bar 106 and the ball 108 to push each into a locked position. The clamp 104 is thereby locked. The inner floating block 116 acts as a locking wedge between the ball 108 and the accessory bar 106, thereby locking both using a common clamping action. The clamp 104 is unlocked by rotating the handle 144 in the opposite direction so as to release the end 142 of the bolt 140 from exerting pressure on the urging face 136 of the inner floating block 116 The ball-locking clamp assembly of the present invention exhibits a number of advantages.

First, by laterally offsetting the rotational axis of the manually operable threaded handle 144 relative to location of the ramp 128, and thereby the wedge portion 132, that engages the accessory bar 106, the leverage applied to the inner floating block 116 by rotation of the handle 144 is increased. Therefore the clamping force applied to the clamp assembly for a given rotation of the handle 144 is greatly increased.

Second, the inner floating block 116 of the clamplO4 is prevented from rotating about an axis orthogonal to the axis of the accessory bar 106 by the provision of the end 142 of the threaded bolt 140 bemg received in the groove 137. Therefore the cavity 119 is always maintained In rotational alignment with the opposed through-holes 114. The accessory bar 106 can readily be removed from the clamp 104 without any danger of inadvertent rotation of the inner floating block 116, and so it is readily possible to reinsert the same or a different accessory bar 106 into the clamp 104.

Accordingly, in the ball-locking clamp assembly of the present invention, the clamp 104 can be removably attached to a selected one of a plurality of different accessory bars 106.

There is no requirement for the clamp to be held captive on the accessory bar. This greatly enhances the versatility of the ball-locking clamp assembly of the present invention.

Also, a cover member 165 can be fitted into the end of the housing 112 remote from the ball 108 so as to inhibit or prevent bacteria or infection from entering the housing 112, because it is not necessary to provide any access to the interior of the housing 112.

Third, the clamp handle 144 can be reliably maintained by the leaf spring in a compact (parked) position, substantially adjacent to the clamp housing 112. The provision of the leaf spring 145 however readily permits the handle to be temporarily moved from this position, when it is desired to operate the handle 144, without requiring a high manual force. Therefore the handle 144 is easy and convenient for medical personnel to operate manually.

Claims

CLAIMS: 1. A clamp for mounting an accessory to a surgical table, the

clamp comprising a mounting element for mounting the clamp to a surgical table, the mounting element having a ball, a clamp housing which at least partially contains the ball and includes an annular seat for the ball, the ball being selectively rotatable in the seat, the clamp housing having two opposed through-holes therein which define therebetween a pathway through the clamp housing for, in use, receiving an elongate bar of an accessory for a surgical table, a locking member disposed in the clamp housing, the locking member having a concave first surface for mating with an outer surface of the ball and a second surface adjacent to the pathway for mating with an outer surface of an elongate bar extending along the pathway, the first surface and the second surface defining therebetween a wedge portion, a threaded opening in the clamp housing, a threaded member extending through the threaded opening into the clamp housing and engaging an urging face of the locking member, the threaded member having a rotational axis, wherein the pathway is laterally spaced from the rotational axis of the threaded member.
2. A clamp according to claim 1 wherein the pathway is located between the ball and the rotational axis of the threaded member.
3. A clamp according to claim 1 or claim 2 wherein the locking member has a cavity extending therethrough, the cavity partially defining the pathway for receiving the elongate bar, and an inner surface of the cavity comprising the second surface.
4. A clamp according to claim 3 wherein the cavity is substantially oval.
5. A clamp according to any foregoing claim wherein the second surface is a ramp surface inclined at an acute angle to the rotational axis of the threaded member.
6. A clamp according to any foregoing claim further comprising a biasing member for biasing the urging face of the locking member against the threaded member.
7. A clamp according to claim 6 wherein the biasing member comprises a compression spring.
8. A clamp according to any foregoing claim further comprising a rotation preventing device for preventing rotation of the locking member in the housing.
9. A clamp according to claim 8 wherein the rotation preventing device comprises a recess in the locking member receiving an end of the threaded member, the recess including the urging face.
10. A clamp according to any foregoing claim further comprising a manually operable elongate handle mounted on the threaded member, the handle having a leaf spring for biasing the handle at least to a position orthogonal to the rotational axis of the threaded member.
11. A clamp according to claim 10 wherein the leaf spring has an outer surface which Is biased against an outer cylindrical surface of the threaded member.
12. A clamp according to claim 10 or claim 11 wherein the leaf spring and the handle are integrally moulded.
13. A clamp according to any foregoing claim further comprising at least one accessory for a surgical table, the accessory being mounted on an accessory bar, the accessory bar extending through the clamp housing along the pathway.
14 A clamp according to claim 13 wherein the accessory bar is selectively removable from the clamp, when unclamped, by sliding the accessory bar out of the clamp housing along the pathway.
15. The combination of a clamp according to any foregoing claim and a plurality of accessory bars therefor, each accessory bar having mounted thereon a respective accessory for a surgical table, and each accessory bar being selectively locatable so as to extend through the clamp housing along the pathway.
16. A clamp for mounting an accessory to a surgical table substantially as hereinbefore described with reference to Figures 1 to 4 of the accompanying drawings.