EP0389188A2

EP0389188A2 - Adjustable support device for surgery

Info

Publication number: EP0389188A2
Application number: EP90302823A
Authority: EP
Inventors: Ram Kumar Chatterjee
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-03-21
Filing date: 1990-03-15
Publication date: 1990-09-26
Also published as: GB2229366A; GB2229366B; GB8906490D0; EP0389188A3

Abstract

An adjustable patient support which is particularly useful in spinal surgery, comprises a base (10), first and second support members (32,34) extending upwardly from the base and being slidably located in an elongate guide (26) in the base. A threaded bar (62) is mounted for rotation about its longitudinal axis which is aligned parallel to the longitudinal axis of the guide (26), and is provided with two portions threaded in opposite senses. Each threaded portion is received in a complementarily-shaped recess in a respective one of the support members (32,34), whereby rotation of the bar causes relative movement of the two support members along the guide groove. The support members each comprise a base portion and a patient engagement portion, and there are means for adjusting the height of the patient engagement portion.

The invention permits unobstructed access to the spine, and since the majority of the weight of the patient is supported on the device, the blockage of arteries and veins is alleviated or prevented. The device also allows an anaesthetist to check that the patient is still breathing, by feeling the movement of the patient's abdomen.

Description

The present invention relates to adjustable support devices for surgery, and in particular, but not exclusively to orthostatic props for use in spinal surgery.
When a patient's spine is operated on, it is necessary to position the patient in such a way as to allow unimpeded access to the spinal area by the surgeon. One way of positioning the patient is to place the patient in a kneeling position on an operating table with the knees under the stomach, and with the patient's chest supported by cushions or pillows placed in front. This, however, has the disadvantage that certain arteries and veins in the patient's upper leg region might be kinked by the flexion of the hips and knees, thus interfering with the patient's circulation. Complications might ensue if such interference occurs throughout the length of an operation. An alternative arrangement is where a patient is laid in the prone position, with the knees and hips flexed over an angled adjustable operating table and being supported bypads at the back of the thighs. Although this does not restrict the patient's circulation, it has the important disadvantage that the patient's chest and stomach are in contact with the operating table, which prevents an anaesthetist from checking the patient's breathing by the preferred method of placing a hand in contact with the patient's abdomen and feeling the expansion and contraction as the patient breathes. Obviously, the checking of a patient's breathing is absolutely vital during the operation.
It will also be noted that the above two arrangements of the patient on the operating table have the further disadvantage that the patient is in a relatively unstable position. Bearing in mind that the patient is unconscious all the time while on the operating table, it will be appreciated that it is quite possible for the patient to fall off the table accidentally, if he or she is not correctly supported.
A third position presently used is with a patient on his or her side. This position does not restrict circulation and allows an anaesthetist to check respiration as described previously, but has the disadvantage that blood tends to flow from the upper side of the patient's body, down over the operation area of the spine, thereby seriously obscuring the surgeon's view of the operative field.
It is an object of the present invention to (i) provide a device which allows stable positioning of a patient for spinal surgery; (ii) to allow the surgeon free access to the posterior lumbar spine and posterior iliac crests to obtain bone graft for posterior spinal fusion; (iii) to eliminate the disadvantages associated with known positions.
In accordance with the present invention, an adjustable patient support for spinal surgery comprises a base, first and second support members mounted on, and extending upwardly from, the base, and displacement means for varying the separation of the support members.
By adjusting the separation of the support members to correspond to the measured separation of a patient's anterior iliac crests, the patient in the prone position can be supported with one anterior iliac crest located on each support member. This produces a firm, supported, stable position in which no veins or arteries are affected, and in which the patient's chest is supported by pillows. The abdomen is free to allow patient breathing, and to allow an anaesthetist to check the patient's respiration.
In a preferred embodiment, the support members are movable in a straight line relative to each other to vary their separation. One, or more preferably both, of the support members are preferably movably mounted on the base. The or each movable support member may conveniently be slidably mounted with respect to the base, and this may be achieved by locating the or each slidable support member in a guide track in the base.
The displacement means for varying the separation may comprise a screw-threaded bar pivotally mounted about its longitudinal axis which lies parallel with the axis of the adjustment direction of the or each support member. The screw-threaded bar would be received in a correspondingly threaded aperture in the or each movable support member, whereby rotation of the screw threaded bar causes the separation of the support members to vary. Where both support members are movable, the portion of the screw-threaded bar to be received in the aperture of one of the support members would be threaded in the opposite sense from the portion of the screw-threaded bar to be received in the aperture of the other support member.
Preferably, there are means for adjusting the height of the support members. This may be achieved by providing support members comprising a base portion and a patient engagement portion, the base portion and the patient engagement portion being connected by a screw-threaded connection. Conveniently, the patient engagement portion may be provided with a threaded shank which projects from the underneath, and which is receivable in a complementarily-threaded aperture in the base portion. Preferably, securing means are provided to releasably secure each support member at a selected height.
Preferably, the support members are concave, in order to provide a stable support for the patient, and to reduce the likelihood of a patient accidentally falling from the support. The support members are also preferably padded, at least in the regions which are intended, in use, to contact a patient. The device may also be provided with a scale to allow easy adjustment of the support members to the desired separation.
The present invention also includes an adjustable patient support for spinal surgery comprising a base, first and second support members extending upwardly from the base and slidably located in an elongate guide groove in the base, a threaded bar mounted for rotation about its longitudinal axis which is aligned parallel to the longitudinal axis of the guide groove, the bar being provided with two portions threaded in opposite senses, each threaded portion being received in a complementarily shaped recess in a respective one of the support members, whereby rotation of the bar causes relative movement of the two support members along the guide groove.
By way of example only, specific embodiments of the present invention will now be described, with reference to the accompanying drawings, in which:-

Fig. 1 is a perspective view of a first embodiment of orthostatic prop for spinal surgery, in accordance with the present invention;
Fig. 2 is a view of the prop of Fig. 1, looking in the direction of arrow X;
Fig. 3 is an exploded perspective view of a support mounting portion of a support of the prop of Fig. 1;
Fig. 4 is a perspective view of a second embodiment of orthostatic prop for spinal surgery, in accordance with the present invention;
Fig. 5 is a perspective view of a third embodiment of orthostatic prop, in accordance with the present invention; and
Fig. 6 is a cross-sectioned side elevation through a portion of the prop of Fig. 5.

Referring firstly to Fig. 1, the orthostatic prop comprises a base portion 10 and two movable support members 12, 14 slidably mounted on the base 10. The base comprises a planar, flat lower portion 16, which is generally rectangular in shape but which has four generally rectangular feet 18 located one at each corner, and two elongate L- shaped members 20, 22 screwed and dowelled to the lower portion 16. The L- shaped members 20, 22 are secured such that the free flanges face each other, and the outer edges of the members 20, 22 are aligned with the respective edges of the generally rectangular portion 16 of the base, thereby forming a central, elongate guide passage 24 having two undercut portions 26.
The movable support members 12, 14 each comprise a respective padded, concave patient support portion 28, 30 which is mounted on a respective mounting block 32, 34 of high density polythene. Each patient support portion 28, 30 is provided with a threaded shank 36 extending from the underside, and the shank is received in a complementarily-threaded collar 38 which is in turn received in an aperture 40 provided in the blocks 32, 34. The collar 38 is a split collar, and two parallel flanges 42, 44 extend from the collar and define the split. When the collar is in position in the aperture 40 in the block 32, the flanges are located in a slot 46 provided in the wall of the block 32. The location of the flanges in the slot prevent the collar from rotating to any substantial degree, and allow the threaded shank 36 of the supports to be screwed into and out of the collar, thereby varying the height of the supports above the base. As indicated in Fig. 3, the depth of the aperture 40 is such that it can receive the shank 36.
The supports may be releasably secured at the desired height by tightening a butterfly nut 48 which is received on a threaded bolt 50 whose shank passes through the flanges 42, 44 thereby causing the collar 38 to tighten about the shank 36 of the support and preventing further rotation of the shank.
Each mounting block comprises a generally cuboidal lower portion 52 and an upwardly tapering middle portion 54, the middle portion being capped by a cuboidal cap 56, in which the aperture 40 and slot 46 are provided. As best seen in Fig. 2, the sides of the lower portion of each block are provided with elongate flanges 58, 60 which are shaped to engage with the undercuts 26 and to be a slidable fit therein. The width of the lower portion is also equal to the width of the central elongate guide passage 24. Thus, the two mounting blocks are slidable in the longitudinal direction of the base only.
In order to displace the mounting blocks (and hence the supports mounted thereon) a screw-advancing mechanism is used. The mechanism comprises an elongate bar 62 which is mounted for rotation about its elongate axis which is disposed parallel to, and in the centre of, the elongate axis of the elongate guide passage 24. The bar is rotatably mounted in three mounting lugs 64, 66, 68, situated in the elongate guide passage and glued to the surface of the portion 16, one lug adjacent to each end of the passage and one lug at the centre. The portions of the bar 62 on either side of the central lug 66 are screw-threaded, but in opposite senses, and each screw-threaded portion is received in a complementarily-threaded through aperture in a respective one of the mounting blocks 32, 34. Thus as the bar is rotated, the mounting blocks move towards or away from each other due to the oppositely-threaded portions of the rod, depending on the direction of rotation. Rotation of the bar is effected by turning a knurled wheel 10 connected to one end of the threaded rod which extends through one mounting lug 64. The wheel may also be rotated by means of a handle 72 mounted on the wheel 70.
The separation of the patient support members may be accurately achieved by means of a calibrated scale 74 secured to the upper surface of the L-shaped member 20. The separation (which is actually the separation of the elongate axes of the shank portions 36 of the supports) is determined by aligning a reference mark 76 on one of the mounting blocks with the desired separation indicated on the scale, and by rotating the threaded rod accordingly.
In use, the distance between the two anterior iliac crests of a patient is accurately measured, and the separation of the patient support members is adjusted as described above to correspond to this distance. The height of the two patient support members is then adjusted as described previously, and the support members are locked in position at the desired height, using the butterfly nuts. In general, the more obese a patient is, the higher the support members should be positioned, so that the patient's weight is mainly supported on the anterior iliac crests rather than on the patient's flesh. The patient is then positioned on the device, which is located transversely on a multi-section operating table, just above the middle break with the anterior iliac crests above the threaded shanks of the support portions. The table will normally be broken at 30^o extension in the middle and 30^o flexion at the lower piece, thus flexing the patient's lumbar spine and keeping the spine horizontal.
The invention permits unobstructed access to the spine, and to both the posterior iliac crests to obtain bone grafts if posterior spinal fusion is required. Furthermore, since the majority of the weight of the patient is supported on the device, the blockage of arteries and veins, especially in the legs, is alleviated or prevented. Moreover, the device allows an anaesthetist to check from time to time that the patient is still breathing, by feeling the movement of the patient's abdomen.
The second embodiment, illustrated in Fig. 4, is very similar to the first embodiment, and identical reference numerals have been used for identical components. The main differences are that the mouting block 34 of the support member 14 is not movable, but instead is glued or otherwise affixed (e.g. bolted) to the base of the guide passage 24, and the threaded bar 62′ is approximately half the length of the bar 62 of the first embodiment and is only received on the other support member 12, thus obviating the requirement for the lug 68, which is not present. Thus, only one 12 of the support members is movable with respect to the base 10, the other support member 14 being fixed relative to the base. The movement of the support member 12 along the guide passage 24 is achieved as before, namely by rotating the screw-threaded rod 62′ passing therethrough. The operation of this embodiment, including the height of the patient support portions 28, 30, is identical to that of the first embodiment.
A third embodiment of the present invention is illustrated in Figs. 5 and 6.
The third embodiments is very similar to the first embodiment, and comprises a base portion 10′ having a central, elongate guide passage 24′ in which two movable support members 12′, 14′ are slidably disposed. In contrast to the first embodiment, the upper and lower faces of undercut portions 26′ of the guide passage 24′ are not parallel with one another, but rather the upper wall slopes upwardly towards the central longitudinal axis of the base 10′. Also in contrast with the first embodiment, the elongate walls 27′ of the overhands forming the undercut portions 26′ are not vertical, but instead slope outwardly to define a downwardly tapering elongate aperture. The movable support members 12′ , 14′ are complementarily shaped with the profile of the central elongate aperture.
It will also be noted that the upper faces of the generally rectangular feet 18′ are inclined upwardly to the central portion of the base 10′, and are contiguous with its sloped upper surfaces. Also, the central mounting lug 66 of the first embodiment has been dispensed with, and is replaced with two bored cylindrical lugs 64′, 68′, one located at either end of the longitudinal guide in the base 10′. The knurled wheel 70 of the first embodiment which was used to rotate the threaded bar 62 has been replaced with a four-lobed knob 80 which is connected rigidly to the threaded bar 62.
The main difference between the third embodiment and the first embodiment is the means for altering the height of the support members 12′, 14′. As in the first embodiment, each mounting block comprises a generally cuboidal lower portion 52′, an upwardly tapering middle portion 54′ and a further upper tapering portion 56′. Each mounting block is provided with a central, vertical square-section through-aperture 82, and each aperture 82 is adapted to receive a complementarily-shaped shank 84 which extends from the underside of the respective patient support portion 28′, 30′ of the respective movable support members 12′, 14′.
As best seen in Fig. 6, one face of the square-section shank 84 is provided with a plurality of saw teeth 86, forming a ratchet bar arrangement, the teeth being engageable with a pawl 88 which is mounted about a horizontal pivot pin 90 attached to the upwardly tapering middle portion 54′ of the mounting block. The pawl is a two-armed pawl, and is biassed towards engagement with the teeth 86 on the shank 84 by means of a torsion spring 92 positioned around the pivot 90. As best seen in Fig. 5, one face of each upwardly tapering middle portion 54′ of each mounting block is provided with a recess 94 which allows the pawl to be pivoted about the pivot 90 out of engagement with the teeth 86 on the square-section shank 84.
In use, the separation of the supports is achieved as before, by rotation of the threaded shank 62 having oppositely-screw threaded portions which engage in complementarily-threaded apertures in the respective generally cuboidal lower portions 52 of the mounting blocks. In order to adjust the height of the supports, the patient support portion 28′, 30′ is pulled upwardly to the desired height. Engagement of the pawl 88 with a tooth 86 at the desired height locks the support portion in position at that height. If it is desired to lower a patient support portion, it is merely necessary to depress the lower arm of the pawl against the force of the spring 92, whereupon the pawl disengages from the teeth 86, allowing the patient support portion to be lowered. When the desired height has been reached, the lower arm of the pawl is released, allowing the upper arm of the pawl to engage with a teeth 86 at the desired height. It should be noted that the patient support portions are prevented from rotating in the apertures 82, since the apertures 82 and the shank 84 are both of square section.
Although the present invention has been described as being most useful for spinal surgery, the stabilised position in which a patient can be held by the device is also very suitable for use in neurosurgery and in general surgery.

Claims

1. An adjustable patient support for spinal surgery, comprising a base (10), first and second support members (12,14) mounted on, and extending upwardly from, the base, and displacement means (62) for varying the separation of the support members.

2. A support as claimed in claim 1, wherein the support members (12,14) are movable in a straight line relative to each other in order to vary their separation.

3. A support as claimed in claim 2, wherein both the support members are movably mounted on the base.

4. A support as claimed in any of the preceding claims, wherein the or each movable support member (12,14) is slidably mounted with respect to the base.

5. A support as claimed in claim 4, comprising a guide (24) on the base along which the or each support member is slidable.

6. A support as claimed in any of the preceding claims, wherein the displacement means for varying the separation of the support members comprises a screw-threaded bar (62) pivotally mounted about its longitudinal axis which lies parallel with the axis of the adjustment direction of the or each support member (12,14), the screw-threaded bar being received in a correspondingly threaded aperture in the or each movable support member (12,14).

7. A support as claimed in claim 6, wherein both support members are movable, and wherein the portion of the screw-threaded bar (62) to be received in the threaded aperture of one of the support members (12) is threaded in the opposite sense from the portion of the screw-threaded bar to be received in the threaded aperture of the other support member (14).

8. A support as claimed in any of the preceding claims, further comprising means for adjusting the height of the support members.

9. A support as claimed in claim 8, wherein the support members comprise a base portion (32,34) which is movable relative to the base (10), and a patient engagement portion (28,30) movable relative to said base portion.

10. A support as claimed in claim 9, wherein the base portion (32,34) and the patient engagement portion (28,30) of each support member is connected by a screw-threaded connection.

11. A support as claimed in claim 10, wherein the patient engagement portion is provided with a threaded shank (36) which is receivable in a complementarily-threaded aperture (40) in the base portion (32,34).

12. A support as claimed in claim 9, wherein the patient engagement portion (28′ ,30′) is provided with a shank (84) which is slidably received in the base portion, and which is provided with a plurality of recesses (86) engageable by a retaining member (88).

13. A support as claimed in claim 11 or claim 12, wherein the retaining member is pivotally mounted on the support member.

14. A support as claimed in claim 11, wherein the retaining member is spring-loaded towards engagement with the shank.

15. A support as claimed in any of the preceding claims, wherein the portions of the support members intended for engagement with a patient are concave.

16. A support as claimed in any of the preceding claims, wherein the portions of the support members intended for engagement with a patient are padded.

17. An adjustable patient support for spinal surgery, comprising a base (10), first and second support members (12,14) extending upwardly from the base and being slidably located on an elongate guide (24) in the base, a threaded bar (62) mounted for rotation about its longitudinal axis which is aligned parallel to the longitudinal axis of the guide, the bar being provided with two portions threaded in opposite senses, each threaded portion being received in a complementarily threaded recess in a respective one of the support members (12,14), whereby rotation of the bar causes relative movement of the two support members (12,14) along the base (10).