Clamping device

Abstract: 1. A clamping device (10) for clampingly interconnecting a first elongate element (17) and a second elongate element (15). The clamping device (10) comprises a shaft (19), and a first clamping member (21) mounted on the shaft. The first clamping member (21) has first and second clamping sections (31, 32) between which the first elongate element (17) can be slidingly received and clampingly engaged. An aperture (73) is provided in the shaft (19) adjacent the second section (32) of the first clamping member (21) to slidingly receive the second elongate member (15). A second clamping member (22) is mounted on the shaft (19) and is displaceable therealong for clamping the second elongate element (15) between the first clamping member (21) and the second clamping member (22). A cam locking mechanism (23) is operably connected to the shaft (19) for selectively moving the clamping device between clamping and non-clamping conditions. In moving the clamping device (10) into the clamping condition, the cam locking mechanism (23) causes displacement of the second clamping member (22) along the shaft (19) such that the second elongate element (15) is clampingly engaged between the first clamping member (21) and the second clamping member (22).

Description: BACKGROUND OF THE INVENTION The present invention relates to a clamping device for interconnecting two elongate elements. The clamping device has been devised particularly, although not necessarily solely, for use with surgical retractors. In surgical operations requiring access to internal organs and bone structures, it is common to use retractors to hold back tissue about the surgical site, so as to expose the area in which surgery is to be performed. Typically, a retractor includes a retractor blade which engages the tissue, and a retractor shaft onto which the retractor blade is mounted. The retractor is attached to a retractor support structure by some form of clamping device. The retractor support structure typically includes a rail which the clamping device can engage to thereby connect the retractor to the retractor support structure. It is important that the clamping devices allow the retractors to be conveniently positioned on the retractor support structure and to be conveniently adjusted as necessary to achieve appropriate positioning with respect to the surgical site. Additionally, it is important that the clamping devices should not pose any significant obstruction to access to the surgical site and to movement of personnel about the surgical site, during the surgical procedure. Various types of clamping devices have been proposed including those disclosed in US Patents 5,727,899 (Dobrovolny), and 5,888,197 (Mulac); and International Application Number WO-A-9730636. Each of those patents discloses a clamping device which includes a first clamping member for releasably engaging a retractor shaft, a second clamping member for releasably engaging a rail forming part of a retractor support structure, and a shaft which extends between the first and second clamping members and which is operable in association with a camming mechanism to cause the first and second clamping members to move between clamping and non-clamping conditions. Each clamping member includes a mounting section which is mounted on the shaft and a clamping section which is offset from the shaft. Typically, the clamping section includes a clamping aperture in which the component undergoing clamping is received. While such arrangements have proved satisfactory in operation, they do suffer from several deficiencies. One deficiency is that the clamping device does not lend itself to a compact construction owing to the fact that the clamping section of each clamping member is offset with respect to the shaft on which the clamping members are supported. Secondly, the offset relationship between the shaft of the clamping device and the retractor shaft renders the retractor vulnerable to deflection in the event of accidental impact during the surgical procedure. Thirdly, cleaning of and sterilisation of the clamping devices is rendered difficult where they contain large numbers of operational parts. Furthermore, it can sometimes be difficult to insert the retractor shaft of a retractor in the clamping aperture of the appropriate clamping member owing to the close tolerances required for the clamping aperture in order for it to effectively move between clamping and non-clamping conditions upon operation of the clamping device. As a result of the close tolerances, there is little opportunity to accommodate misalignment between the retractor shaft and the clamping aperture when the clamping shaft is being presented to the clamping aperture for insertion therein during the process of setting up the retractor system. US Patent Number 3572326 upon which the two-part form of claim 1 is based discloses a clamping device for use in retractor assemblies and requires multiple separate components including a screw fitting to tighten the clamp, also this device is limited to receiving predefined retractor shafts and the clamping is dependent on force created through sliding movement of a cylindrical knob inside a hollow sleeve. It is against this background, and the problems and deficiencies associated therewith, that the present invention has been developed. SUMMARY OF THE INVENTION The present invention provides a clamping device for clampingly interconnecting first and second elongate elements, the clamping device comprising a shaft, a first clamping member mounted on the shaft, the first clamping member having first and second clamping sections between which the first elongate element can be slidingly received and clampingly engaged, an aperture in the shaft to slidingly receive the second elongate element, a separate second clamping member mounted on the shaft and being displaceable there along for clamping the second elongate element between the first clamping member and the second clamping member characterised in that a cam locking mechanism operatively connected to the shaft applies a compressive force between the second clamping member and the first clamping section of the first clamping member thereby to cause clamping engagement of the first and second elongate elements and in that said aperture is arranged adjacent the second section of the first clamping member such that second elongate element is clamped between said second section of said first clamping member and said second member. Preferably, the cam locking mechanism includes a cam pivotably connected to the shaft and a handle connected to the cam for pivotally moving the cam between clamping and release positions, wherein during movement towards the clamping position the cam contacts the second clamping member to cause displacement thereof along the shaft. Preferably, the first clamping member is a unitary construction whereby the first and second sections are connected by an integral hinge section located remote from the portions of the first and second sections that receive the first elongate element. Preferably, the first and second sections of the first clamping member are resiliently movable with respect to each other from the clamping condition to the non-clamping condition. Preferably, the second clamping member comprises a body having an opening through which the shaft is received, the body presenting a clamping face for engagement with the elongate element received in the aperture in the shaft. Preferably, the second clamping member further comprises an abutment member positioned adjacent the body on the side thereof remote from the aperture in the shaft. Preferably, the abutment member is formed of low-friction plastics material. Preferably, the aperture formed in the shaft is of a size whereby a loose fit is provided between the aperture and the elongate element received therein. Preferably, the aperture is elongated with the longitudinal axis thereof extending along the longitudinal axis of the shaft. Preferably, a stop is provided on the shaft to limit the extent to which the second clamping member can be displaced along the shaft. Preferably, the shaft is threadingly connected to the first clamping section. Preferably, the first clamping member is adapted for engaging a support rail for a retractor assembly. Preferably, the aperture in the shaft adjacent the first clamping member is adapted to slidingly receive a retractor shaft. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood by reference to the following description of one specific embodiment thereof in which: Figure 1 is a perspective view of a clamping device according to the embodiment; Figure 2 is a view similar to figure 1 with the exception that the clamping device is showing connecting a retractor shaft to a support rail of a retractor support structure; Figure 3 is a sectional elevation of the clamping device shown in a non-clamping condition; Figure 4 is a view similar to figure 3 with the exception that the clamping device is shown in a clamping condition; Figure 5 is a sectional side view of the clamping device shown in a non-clamping condition; Figure 6 is a view similar to figure 5 with the exception that the clamping device is shown in a clamping condition; and Figure 7 is an exploded view of the clamping device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The embodiment shown in the drawings is directed to a clamping device 10 for use in connecting a retractor 11 to a retractor support structure 13. In a typical case, the retractor support structure 13 is used to support one or more of such retractors 11 above an operating table. Each retractor 11 includes a retractor shaft 15 on one end of which is supported a retractor blade (not shown) which holds back tissue adjacent a surgical site in a patient in known manner so as to provide access to the site. The retractor support structure 11 includes an elongate element which provides a rail 17 onto which the retractor shaft 15 is mounted by way of the clamping device 10. The retractor shaft 15 and the rail 17 are both of circular cross-section. The clamping device 10 allows the retractor 11 to be adjusted in position with respect to the rail 17 as necessary. The clamping device 10 comprises a shaft 19, a first clamping member 21 mounted on the shaft 19 and a second clamping member 22 also mounted on the shaft 19. The clamping device 10 further comprises a cam locking mechanism 23 operatively connected to the shaft 19 for moving the clamping device between non-clamping and clamping conditions, as will be explained in detail later. The first clamping member 21 comprises a clamping body 27 which is of unitary construction and which has an inner face 28 and an outer face 29. The clamping body 27 includes a first clamping section 31 and a second clamping section 32 connected together at one end thereof by a section which provides an integral hinge 33. A clamping aperture 35 is provided in the end of the clamping body 27 remote from the integral hinge 33. A gap 37 defined between the upper and lower clamping sections 31 and 32 respectively extends between the clamping aperture 35 and a bore 39 in the body adjacent the hinge 33. The bore 39 serves to assist operation of the integral hinge 33. The gap 37 allows the two clamping sections 31, 32 to resiliently flex with respect to each other about the integral hinge 33, thereby expanding and contracting the clamping aperture 35. The resilient nature of the clamping body 27 biasses the clamping aperture 35 into the expanded condition. The clamping aperture 35 is defined by two recesses 41, one formed in the first clamping section 31 and the other formed in the second clamping section 32. The recesses 41 define an arcuate jaw which is of a configuration accommodating the circular rail 17 and which has a mouth 42. A bevel 43 is provided adjacent each recess 41 to provide a guide surface for guiding the rail 17 into the clamping aperture. The rail 17 can enter the clamping aperture 35 sidewardly through the mouth 42 when the clamping aperture 35 is in the expanded condition, as indicated by arrow 44 in figure 5. The first clamping member 21 has a bore 47 extending through the clamping body 27. The bore 47 provides a first hole 51 in the first clamping section 31 and a second hole 52 in the second clamping section 32. The shaft 19 includes a male threaded section 53 at one end thereof, a lug section 55 at the other end thereof, and an intermediate shank section 57 between the threaded section 53 and the lug section 55. A step 59 is provided at the junction between the intermediate section 57 and the threaded section 53. The threaded connection 45 between the shaft 19 and the first clamping section 31 is provided by a retainer 61 which threadingly engages the threaded section 53 of the shaft 19. The threaded section 53 of the shaft 19 is received in, and projects beyond, the first hole 51 of the first clamping section 31, as seen in figure 3 of the drawings. The step 59 on the shaft 19 bears on the inner face of the first clamping section 31. The retainer 61 is accommodated within a recess 65 formed in the outer face 29 of the first clamping section 31. With this arrangement, the shaft 19 is engaged to the first clamping section 31 of the first clamping member 21. The intermediate section 57 of the shaft 19 extends through the second hole 52 in the second clamping section 32 without being connected thereto so as to allow the first and second clamping sections 31, 32 to flex resiliently with respect to each other without interference by the shaft 19. The first hole 51 provides a bore 64 of reduced size to accommodate the threaded section 53 of the shaft 19. The second clamping member 22 is slidably positioned on the shaft 19. More particularly, the second clamping member 22 is slidably positioned on the lug section 55 of the shaft and has a central hole 67 through which the lug section is received. With this arrangement, the second clamping portion 22 can undergo limited displacement along the shaft 19. The extent to which the second clamping member 22 can be displaced along the shaft 19 in the direction towards the first clamping member 21 is limited by a stop 71 in the form of a collar formed integrally on the shaft. The second clamping member 22 presents a clamping face 72. An aperture 73 is provided in the shaft 19 and is so positioned such that it is immediately adjacent the inner face 28 of the first clamping member 21, as well as generally between the first clamping member 21 and the second clamping member 22, (as best seen in figures 3 and 4 of the drawings). The aperture 73 is of a size whereby it can receive the retractor shaft 15 with a loose fit. Indeed, the aperture 73 is elongated in the longitudinal direction of the shaft 19 so as to provide the loose fit. The loose fit is provided to assist insertion of the retractor shaft 15 into the aperture 73. With the retractor shaft 15 received in the aperture 73, the retractor shaft 15 can be clamped between the first clamping member 21 and the second clamping member 22. More particularly, the retractor shaft 15 is clamped between the inner face 28 on the first clamping member 21 and the clamping face 72 on the second clamping member 22. The stop 71 limits the extent to which the second clamping member 22 can move along the shaft 19 into a position in which it covers the aperture 73. Even with the second clamping member 22 displaced into a condition in which it bears against the stop 71, the aperture 73 is sufficiently exposed to allow access for insertion of the retractor shaft 15. In the absence of the stop 71, it is likely that the second clamping member 22 would locate against the first clamping member 21 and thereby interfere with insertion of the retractor shaft 15 in the aperture 73. The second clamping member 22 comprises a first portion 81 and a second portion 82. The first portion 81 is formed of rigid material such as stainless steel and presents the clamping face 72. The first portion 81 is of generally cylindrical construction and incorporates a recess 83 in which the second portion 82 can locate. The second portion 82 is formed of low-friction plastics material and incorporates a cradle 85, the purpose of which will be explained later. The cam locking mechanism 23 is operatively connected to the shaft 19 for providing a compressive force in association with the shaft 19 between the second clamping member 22 and the first clamping section 31 of the first clamping member 21. This compressive force acts to contract the clamping aperture 35 in the first clamping member 21 thereby to clampingly engage the rail 17, and to displace the second clamping member 22 along the shaft 19 towards the first clamping member 21 thereby to clampingly engage the retractor shaft 15 within the aperture 73. The cam locking mechanism 23 comprises a cam 93 which is pivotably connected to the shaft 19, and a handle 95 formed integrally with the cam. The handle 95 provides a lever for operating the cam. The cam 93 comprises two cam sections 97 between which there is a gap 99. The cam 93 is positioned on the shaft 19 with the outer end of the lug section 55 of the shaft 19 received in the gap 99 of the cam. A pivot pin 101 extends through aligned apertures 103, 105 in the cam 93 and the lug section 55 respectively. In this way, the pivot pin 101 pivotally connects the cam 93 to the shaft 19. The cam 93 is accommodated in the cradle 85 within the second portion 82 of the second clamping member 22. The cam 93 has a cam surface 107 which co-acts with the surface 109 of the cradle 85 to cause displacement of the second clamping member 22 upon movement of the cam 93 from a release condition (as shown in figures 3 and 5) to a locking condition (as shown in figure 4 and 6). The axis of rotation of the cam 93 about the pin 101 is normal to the central axis of the aperture 73. In this way, the longitudinal extent of the handle 95 is generally in the same direction as the retractor shaft 15 when the cam is in the locking condition, as best seen in figure 2 and 6 of the drawings. This is particularly advantageous in that it promotes a compact arrangement when the clamping device 10 is in a clamping condition, thereby reducing the opportunity for the clamping device to pose a significant obstruction to a surgeon and other attendants conducting a surgical procedure. The clamping device 10 according to the embodiment provides a simple yet highly effective arrangement for securely mounting the retractor shaft 15 onto the rail 17 of the retractor support structure. With the clamping device 10 in a non-clamping condition, the first clamping member 21 is positioned on the rail 17 of the retractor support structure, with the rail received in the clamping aperture 35. The retractor shaft 15 is then positioned within the aperture 73 such that it is between the first clamping member 21 and the second clamping member 22. The position of the retractor blade (not shown) can be adjusted with respect to the surgical site as necessary by various actions including linear and angular adjustment of the clamping device is with respect to the rail 17, and linear and angular adjustment of the retractor shaft 15 with respect to the clamping device 10. Once the retractor blade is in the required position, the cam locking mechanism 23 can be operated so as to move the clamping device 10 from the non-clamping condition to the clamping condition. In the clamping condition, the first clamping member 21 clampingly engages the rail 17, and the first and second clamping members 21 and 22 respectively cooperate to clampingly engage the retractor shaft 15. Upon subsequent release of the cam locking mechanism 23, the resilient nature, of the first clamping member 21 causes expansion of the clamping aperture 35 to release the rail 17 from the clamping condition. This also allows displacement of the second clamping member 22 away from the first clamping member 21 so as to release the retractor shaft 15 from the clamping condition. A particular advantage of the clamping device according to the embodiment is that the retractor shaft 15 is generally aligned with the shaft 19 of the clamping device. This is beneficial in that any accidental knock or impact against the retractor during a surgical procedure is less likely to cause the retractor to swing about the shaft 19 and move the retractor blade out of position. Furthermore, it provides for a more compact construction as compared to the prior art devices described previously. A still further advantage of the clamping device according to the embodiment is that the clamping force applied by the cam locking mechanism 23 is along the line of the shaft 19. In this way, a clamping force transferred through the clamping device 10 is applied to the retractor shaft 15 along the line of action of the force and so provides for a more effective clamping action. The clamping device according to the embodiment can be constructed of any suitable material. A particularly suitable material is stainless steel, which is used throughout the embodiment apart from the second portion 82 of the second clamping member 22 which is of plastics material. From the forgoing, it is evident that the present embodiment provides a simple yet highly effective clamping device for releasably interconnecting first and second elongate elements. It should be appreciated that the scope of the invention is not limited to the scope of the embodiment described. In particular, it should be appreciated that the clamping device according to the invention can be used to clampingly interconnect any suitable elongate elements and that it is not restricted to clamping elongate elements in the form of retractor shafts and rails of retractor support structures.

Claims: A clamping device (10) for clampingly interconnecting first (17) and second (15) elongate elements, the clamping device (10) comprising a shaft (19), a first clamping member (21) mounted on the shaft (19), the first clamping member having first and second clamping sections (31, 32) between which the first elongate element (17) can be slidingly received and clampingly engaged, an aperture (73) in the shaft to slidingly receive the second elongate element (15), a separate second clamping member (22) mounted on the shaft (19) and being displaceable there along for clamping the second elongate element (15) between the first clamping member (21) and the second clamping member (22) characterised in that a cam locking mechanism (23) operatively connected to the shaft (19) applies a compressive force between the second clamping member (22) and the first clamping section (31) of the first clamping member (21) thereby to cause clamping engagement of the first and second elongate elements (17, 15) and in that said aperture (73) is arranged adjacent the second section (32) of the first clamping member (21) such that second elongate element (15) is clamped between said second section (32) of said first clamping member (21) and said second member (22). A clamping device (10) according to claim 1 wherein the cam locking mechanism (23) includes a cam pivotably connected to the shaft (19) and a handle (95) connected to the cam for pivotally moving the cam between clamping and release positions, wherein during movement towards the clamping position the cam contacts the second clamping member (22) to cause displacement thereof along the shaft (19). A clamping device (10) according to any one of the preceding claims wherein the first clamping member (21) is a unitary construction whereby the first (31) and second (32) sections are connected by an integral hinge (33) section located remote from the portions of the first and second sections (31, 32) that receive the first elongate element (17). A clamping device (10) according to any one of the preceding claims wherein the first and second sections (31, 32) of the first clamping member (21) are resiliently movable with respect to each other from the clamping condition to the non-clamping condition. A clamping device (10) according to any one of the preceding claims wherein the second clamping member (22) comprises a body having an opening through (67) which the shaft is received, the body presenting a clamping face (72) for engagement with the elongate element (15) received in the aperture (73) in the shaft (19). A clamping device (10) according to claim 5 wherein the second clamping member (22) further comprises an abutment member (82) positioned adjacent the body on the side thereof remote from the aperture (73) in the shaft (19). A clamping device (10) according to claim 6 wherein the abutment member (82) is formed of low-friction plastics material. A clamping device (10) according to any one of the preceding claims wherein the aperture (73) formed in the shaft (19) is of a size whereby a loose fit is provided between the aperture (73) and the elongate element (15) received therein. A clamping device (10) according to claim 8 wherein the aperture (73) is elongated with the longitudinal axis thereof extending along the longitudinal axis of the shaft (19). A clamping device (10) according to any one of the preceding claims wherein a stop (71) is provided on the shaft (19) to limit the extent to which the second clamping member (22) can be displaced along the shaft (19). A clamping device (10) according to any one of the preceding claims wherein the shaft (19) is threadingly connected to the first clamping section (31). A clamping device (10) according to any one of the preceding claims wherein the first clamping member (22) is adapted for engaging a support rail (17) for a retractor assembly. A clamping device (10) according to claim 12 wherein the aperture (73) in the shaft (19) adjacent the first clamping member (22) is adapted to slidingly receive a retractor shaft (15).

Inventors: GRAY BRUCE NATHANIEL, GRAY, BRUCE NATHANIEL, Gray, Bruce Nathaniel, Pine Ridge Holdings Pty Ltd
Applicants: PINE RIDGE HOLDINGS PTY LTD, PINE RIDGE HOLDINGS PTY LIMITED
Application year: 1999
Main classification: A61B17
IPC codes: A61B17, F16B2, F16B7