GB2218912A - Surgical retractor - Google Patents

Abstract

A surgical retractor has two arms (12) and blades (not shown) attached at 20. A pivotal connection 16 between the arms 12 allows them to be opened and closed to vary the separation of the blades 14 and therefore to vary the size of the wound. A locking mechanism incorporated in the pivotal connection 16 can be used to prevent relative movement of the arms 12 when their positions have been set. <IMAGE>

Description

Surgical Retractor the present invention rclales to surgical retractors, Surgical rclraclors are used to hold the body tissue and organs apart in order to allow a surgeon to have clear access (known as "exposure") to the organ or tissue which is the subject of the operation.

It has long been known for an assistant to hold a retractor blade in each hand and spend the whole of the duration of the operation simply holding these blades apart, to allow adequate exposure for the surgeon.

This arrangement has many disadvantages. The work can be tiring, particulary in the case of deep surgery or surgery on large or obese patients. Fatigue and boredom can give rise to danger of damage being caused to delicate organs, by insufficiently careful handling.

Various attempts have been made to design mechanical retractors which avoid the need for an assistant to operate them once they have been set up, but these have been found to be awkward to use or to have components which interfere with the surgeons access to the cavity which they have opened.

It is therefore an object of the present invention to provide an improved surgical retractor.

According to the present invention, there is provided a surgical retractor comprising two arms, blades mounted on the arms for placing in contact with the tissue of a patient, a pivotal connection between the arms by means of which the arms may be opened and closed to vary the separation of the blades, end a locking mechanism operable to prevent relative movement of the arms, the locking mechanism being incorporated in the pivotal connection.

Preferably the blades are detachably mounted on the arms. The retractor may comprise a set of blades of cii F Fe reri L Forms suil.lblc for holding corresponding organs when inserted in a surgical cavity, the blades being selectively mountable on the arms.

The locking mechanism is preferably operable to prevent the arms closing together while allowing the arms to be opened further. The locking mechanism preferably comprises a ratchet system. The ratchet system may comprise a circular ratchet mounted on one arm, for rotation with that arm relative to the other arm, and a pawl mounted on the said other arm and engagable with the ratchet. The circular ratchet is preferably centred on the pivot axis of the pivotal connection. The ratchet system preferably comprises a resilient member which biasses the pawl into engagement with the ratchet. The resilient member may be a compression spring. The ratchet system may further comprise a release member manually operable to disengage the pawl and the ratchet. The arms are preferably curved between the pivotal connection and the points at which the blades are attached.

One embodiment of a retractor according to the present invention will now be described in more detail, by way of example only, and with reference to the accompanying drawings, in which: Fig. 1 is a front view of the retractor without blades; Fig. 2 is a side view of the retractor, without blades; Fig. 3 is a highly schematic diagram of the ratchet mechanism; and Figs. 4A and 4B show two possible blade designs.

The surgical retractor 10 shown in the drawings comprises two arms 12, and blades 14 (Fig. 4) which are mounted on the arms when the device is in use. There is a pivotal connection 16 between the arms 12 by means of which the arms 12 may be opened and closed to vary the separation of the blades 14. A locking mechanism 18 (Fig. 3) is operable to prevent relative movement of the arms 12. The locking mechanism is incorporated in the pivotal connection 16.

The arms 12 are connected together at one end, and at their free ends they have mounting holes 20 for mounting the blades 14. Between their ends, the arms 12 are curved in two perpendicular planes. In the front view, shown in Fig. 1, the arms 12 are curved to resemble a horseshoe while in the perpendicular plane, shown in Fig. 2, the arms are curved to a lesser degree.

The pivotal connections 16 and locking mechanism 18, to be described below, are housed in a housing 22.

A lever 24 is mounted on a shaft 26 which extends through the housing 22. The lever 24 can be operated to rotate the shaft 26 and release the locking mechanism, as will be described. The housing 22, lever 24, arms 12 and blades 14 are all stainless steel to allow for easy sterilisation, such as by autoclave.

Alternatively, it may be desirable for the whole structure or the arms and blades to be made of a material which is transparent to X-rays to allow the device to be left in place while X-rays are taken during the course of an operation.

The structure of the locking mechanism 18 is indicated in Fig. 3 and the location of the various parts in the housing 22 is indicated in Fig. 2.

The locking mechanism 18 comprises a ratchet disc 28 having a circular ratchet 30 around its circumference. The disc 28 is mounted on the left hand arm shown in Fig. 1 with its centre coincident with the centre of the pivotal connection 16 between the arms 12. This allows the ratchet disc 28 to rotate about its axis in relation to the right hand arm 12 of Fig. 1 when the arms are opened or closed.

A pawl 32 is pivotally mounted at 34 on the right hand arm. The pawl comprises a part-circular disc cut away to provide a tooth region 36 for engaging the ratchet 30, and a flat 38 on the other side of the pivot 34. A compression spring 40 is mounted to act betwen the housing 22 and the flat 38 on the pawl 32, to urge the pawl to rotate in the clockwise direction as shown in Fig. 3. This causes the tooth region 36 to rotate until engaging the ratchet 30. It can be seen from Fig. 3 that the separation of the pivot axis 34 and the tooth region 36 is greater than the separation of the pivot 34 and the ratchet 30 taken along a radius of the disc 28. Accordingly, the tooth region 36 will lie to one side of that radius when the pawl and ratchet are engaged. This choice of dimensions ensures that, once the corner of the pawl 32 at the region 36 has engaged the ratchet 30, the disc 28 is prevented from further anti-clockwise rotation as shown in Fig.

3. This locks the arms 12 from closing. The choice of the dimensions allows the locking to be very strong even when the teeth of the ratchet 30 are small, and the use of small teeth allows the pawl and ratchet to engage immediately the arms 12 begin to close.

Conversely, if the arms 12 are opened, the pawl 32 can be pushed away from the ratchet 30, against the compression spring 40, to allow the arms to open freely. The compression spring 40 ensures that the pawl 32 remains in contact with the ratchet 30 so that the pivotal connection is again locked as soon as the arms cease to be moved apart.

The shaft 26 carrying the lever 24 is attached to the pawl 32, to be co-axial with the pivot axis at 34.

Thus, the locking mechanism can be released to allow the arms 12 to close, simply by pressing the lever 24 until the pawl 32 disengages the ratchet 30.

Figs. 4A and 4B show two possible designs for the blades 14. Each blade is formed from stainless steel sheet and comprises an attachment portion 42 and a working portion 44. The attachment portion 42 is a generally square portion having a central hole 46. The blade 14 is mounted on the end of an arm 12 by means of a screw or bolt passing through the hole 46 and the hole 20 in the arm 12. A bolt may be used which directly engages a thread in the hole 20.

Alternatively, a threaded socket for the bolt may be Fo rmod in a sop. ra Lo socket. nlcrnberr rreceived in the hole 20 which is then preferably non-circular to prevent rotation of the socket member as the bolt is tightened.

The working portions 44 of the blades 14 have dimensions and shapes chosen according to their intended use. The blade shown in Fig. 4A has a curved working portion which could be used for holding the liver up during an operation on the gall bladder or bile ducts. The blade shown in Fig. 48 has a straighter working portion 44 which could be used to hold down the duodenum and small bowel during gall bladder surgery. The blade of Fig. 4A may for instance have a width between one centimetre and six centimetres, according to the size of the patient, and may have a length between three centimetres and twenty centimetres, again according to the type of patient.

The curvature on the working portion 44 is chosen to hold the liver gently, without trauma.

The dimensions of the blade of Fig. 46, and the angle between the working portion 44 and the attachment portion 42 can be varied according to the type of patient and the working methods of the surgeon, but it is expected that the angle between the portions will be in the range 45 degrees to 90 degrees, and the width and length of the blade will be in the same ranges as given above for the blade of Fig. 4A.

In order to use the device, appropriate blades are selected according the the operation being conducted, and these blades are attached to the ends of the arms 12. The blades are then inserted into the cavity and the arms 12 are opened until the organs and tissues are held apart to the satisfaction of the surgeon. It may be appropriate to place small swabs behind the blades to act as a cushion between the blades and the organs.

The locking mechanism 18 will securely lock the arms 12 against closing and therefore ensure that the cavity is kept open.

When the retractor is in position, the curvature of the arms 12 ensures that they interfere to the minimum extent possible with the surgeon's access to the cavity. Similarly, the incorporation of the locking mechanism into the pivotal connection ensures that it does not interfere with access. Finally, the curvature of the arms 12 as shown in Fig. 2 generally follows the curvature of the patient's body, so that the whole device lies close to the surface of the body and causes minimal interference to the freedom of the surgeon.

At the end of the operation, it is a simple matter to release the locking mechanism 18 by operation of the lever 24, thereby allowing the arms 12 to move together and close the cavity.

It will be apparent from the above that variations and modifications to the apparatus described can be made without departing from the spirit and scope of the present invention. In particular, all dimensions of the device described can be changed according to the size of the patient, the nature of the operation and the particular wishes of the surgeon concerned.

Claims (1)

1. A surgical retractor comprising two arms, blades mounted on the arms for placing in contact with the tissue of a patient, a pivotal connection between the arms by means of which the arms may be opened and closed to vary the separation of the blades, and a locking mechanism operable to prevent relative movement of the arms, the locking mechanism being incorporated in the pivotal connection.

2. A retractor according to claim 1, wherein the blades are detachably mounted on the arms.

3. A retractor according to claim 2, further comprising a set of blades of different forms suitable for holding corresponding organs when inserted in a surgical cavity, the blades being selectively mountable on the arms.

4. A retractor according to any preceding claim, wherein the locking mechanism is operable to prevent the arms closing together while allowing the arms to be opened further.

5. A retractor according to claim 4, wherein the locking mechanism comprises a ratchet system.

6. A retractor according to claim 5, wherein the ratchet system comprises a circular ratchet mounted on one arm, for rotation with that arm relative to the other arm, and a pawl mounted on the said other arm and engagable with the ratchet.

7. A retractor according to claim 6, wherein the circular ratchet is centred on the privot axis of the pivotal connection.

8. A retractor according to claim 6 or 7, and comprising a resilient member which biasses the pawl into engagement with the ratchet.

9. A retractor according to claim 8, wherein the resilient member is a compression spring.

10. A retractor according to any of claims 6, 7, 8 and 9, and further comprising a release member manually operable to disengage the pawl and the ratchet.

12. A retractor according to any preceding claim, wherein the arms are curved between the pivotal connection and the points at which the blades are attached.

13. A surgical retractor substantially as described above with reference to the accompanying drawings.

14. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.