GB2544352A

GB2544352A - Surgical tool

Info

Publication number: GB2544352A
Application number: GB1522408.2A
Authority: GB
Inventors: Malcolm Vickery Ian
Original assignee: DENTMED Ltd
Current assignee: DENTMED Ltd
Priority date: 2015-11-06
Filing date: 2015-12-18
Publication date: 2017-05-17
Anticipated expiration: 2035-12-18
Also published as: GB2544352B; GB201519652D0; GB201522408D0

Abstract

A hand-held surgical tool (e.g. drill) having at least one pad of vibration-absorbent material thereon, the pad being of hydrophobic polyurethane foam made from a polyol and isocyanate composition in which the weight ratio of polyol to isocyanate is from 2.5:1 to 1.5:1. A hand-held surgical tool having at least one pad of vibration-absorbent material thereon, the pad having an irrigation duct therethrough connected to means for supplying irrigation fluid to the duct, and a pad for a hand-held surgical tool, wherein the pad has an irrigation duct therethrough connected to means for supplying irrigation fluid to the duct, are also claimed.

Description

SURGICAL TOOL

The present invention relates to a surgical tool which will be hand held.

Surgical procedures involving bone regularly require drilling, reaming, or sectioning of bones such as the femur, tibia, radius, ulna, mandible and others.

The techniques involved often require the surgeon to place one or both arms/hands in unusual and awkward positions for lengthy periods of time. When these unusual positions involve the, sometimes lengthy, use of hand held cutting equipment there can be a neurological effect on the palms and fingers of both hands.

These peripheral neurological effects can take the form of paraesthesia or anaesthesia which can be intermittent, short term, or more prolonged, they may also become worse during or following multiple operation lists.

Should these symptoms be ignored there can a more generalized hand/wrist muscle weakness which can become progressive .

The present invention results from the measurement of vibrations from hand held cutting equipment and decade's long clinical use of a closed cell hydrophobic polyurethane foam.

Although this problem has been appreciated for some time there has been little clinical trial to try and prevent these developments until the arrival of medico-legal implications.

At its most general, a first aspect of the present invention provides one or more pads of hydrophobic polyurethane foam, which are mounted on the tool for vibration absorption.

Thus, this aspect of the present invention may provide a hand-held surgical tool having a pad of vibration-absorbent material, the pad being of hydrophobic polyurethane foam made from a polyol and isocyanate composition in which the weight ratio of polyol to isocyanate is from 2.5:1 to 1.5:1.

An irrigation duct may extend through the pad. The duct may terminate at an external surface of the pad, so that the movement of the tool accurately controls the movement of the termination of the irrigation duct, to allow irrigation to be directed to the region desired.

Indeed, the use of such an irrigation duct in a vibration-absorb pad represents a second independent aspect of the invention. This aspect may provide a hand-held surgical tool having at least one pad of vibration-absorbent material thereon, the pad having an irrigation duct therethrough connected to means for supplying irrigation fluid to the duct.

The tool may be a saw having a handle being a first-hand grip and an elongate surface being a second-hand grip. The surgeon will normally use his right hand to hold the handle, and place his left hand on the elongate surface, which is normally an upper surface of the tool, to steady the tool.

With the present invention, either or both of the handle and the elongate surface may have a pad mounted thereon.

In the subsequent discussion, the pads will be referred to as VM-A and VM-G and may also be referred to as guards.

The polyurethane foam used in the production of units VM-A and VM-G has been approved for intra cavity use since the 1970's and there was, or has been, no prior art demonstrated.

The polyol composition is as listed below -

Polyoxyalkene Triethanolamine Dipropylene glycol Triethyldiamine

Organo-modified polysiloxanes C9-11 alcohol ethoxylate 2 - {[2 - dimethylamino] methylamino} ethanol

The isocyanate composition is -Methylenediphenyl diisocyanate - MDI

The chemical formulations for each of the three samples of the VM-A and VM-G units tested were adjusted in order to confirm the best protection of the palms and fingers from any vibration.

In the polyol and isocyanate composition that forms the or each pad; (i) the polyol may comprise 94.8% by weight polyoxyalkylene triols, 1.8% by weight triethanolamine, 0.2% by weight dipropylene glycol, 0.1% by weight triethyldiamine, 0.4% by weight organo-modified polysiloxanes, 2.1% by weight C9-11 alcohol ethoxylate and 0.6% by weight 2 — [ [2 — dimethylamino)ethyl]methylamino] ethanol, and/or (ii) the isocyanate may (comprise) 50% to 77% by weight diphenylmethanediisocyanate, isomers and homologues thereof, and 23% to 50% by weight isocyanates that are the reaction product of the polyol with methylenediphenyldiisocyanate.

Initial testing VM-OA [top guard], and VM-G [bottom guard], using an unspecified chemical formulation resulted in a reduction from 0.73g to 0.37g when the top guard was in position and 0.44g to 0.13g when bottom guard was in position.

Chemical formulations for three samples of hydrophobic polyurethane for testing against vibrations induced by a hand held battery powered saw with blade attached but with bone cutting/drilling in action.

Top guard - VM-A- aligner. 1.8.5 polyol 3.9 iso. 2.9 polyol 4.5 iso. 3.9 polyol 5 iso.

Bottom guard - VM-G - grip. 1.15 polyol 6.8 iso. 2.12.5 polyol 6.25 iso. 3.12 polyol 6.7 iso.

The three formulations listed above are calculated to increase the "Shore index" for top and bottom guards in the order 1-3 - in essence increasing the density of each unit and therefore the absorption of the vibrations induced by the saw.

All the top and bottom guards have an acrylonitrile butadiene styrene [ABS] onlay positioned directly against the barrell and the grip sections of the saw/drill reducing vibration reaching the hand and fingers of the operation hands .

With this aspect to the overall polyurethane cushion it becomes possible to retain manual dexterity - "feel" - whilst protecting the surgeon's hands.

Measurements have been carried out of the magnitude and frequency of significant vibrations imposed on the hands holding bone cutting and drilling equipment during orthopaedic surgery.

Peak measurements recorded simultaneously from the outer aspects of the distal phalange, the distal metacarpal and the medical metacarpal of the finger of both right and left hands.

When the VM-A and VM-G units are held, a measurement is taken from the outer aspect of the distal phalange of the index finger when this finger is applied to the on/off trigger - this allows seven simultaneous recordings to be taken. Repeated tests during bone cutting may demonstrate total or near total protection from vibrations measured between 5-2000 Hz .

Specialised polyurethane foam with CE & FDS accreditation is used to form two designs of guard - the VM-A & VM-G which are placed between the cutting/drilling instrument and the surfaces of the hands and fingers.

Thus, specific shaped abs onlays are positioned on the external surfaces of the drive shaft of the drill and the grip section each then held in positon by polyurethane foam of known chemical specifications.

Both VM-A & VM-G units withstand porous load autoclaving 134 degrees c 32 psi with a 5 cycle pulsation followed by 50 mb drying cycle without unit distortion.

Embodiments of the present invention will now be described in detail by way of example, with reference to the accompanying drawings .

Fig. 1 shows a surgical tool to which the present invention is applied. The tool has a body 10 with a handle 12 and an elongate upper surface 14. The body 10 is connected to a power head 16. A trigger 18 operated by the surgeon drives the power head 16. Normally, with the saw being driven by the power head 16, to enable cutting, as previously described, but the saw may be replaced by a drill when needed.

In normal use, the surgeon holds the handle 12 in the right hand, to enable to trigger 18 to be operated, and places the left hand on the elongate upper surface 14 to steady the tool. However, the surgeon's hands, particularly the hand on the elongate upper surface 14, are subject to much vibration as previously discussed. Therefore, according to the present invention, at least one vibration absorbing pad is fitted to the tool. In Fig. 1, that pad is pad 20 (VM-A pad) fitted to the elongate upper surface 14 of the tool.

Figs. 2a to 2f show the pad in more detail. Fig. 2a is a perspective view, Figs. 2b and 2c are end views, Fig. 2b is at a longitudinal sectional view through the pad, Fig. 2e is a side view, and Fig. 2f is a sectional view along the line A to A in Fig. 2e. These views show the general shape of the pad 20, which partially covers the upper surface 14, and lying on the upper surface 14.

The outer surface 22 of the pad 20 is shaped to conform to the surgeon's hand, when that hand is positioned on top of the tool, covering the pad 20, whilst the inner surface 24 conforms to the shape of the elongate upper surface 14 on which the pad 20 is mounted.

Figs. 3a and 3b show a modification of the embodiment of Figs. 2a to 2f, in which there is an irrigation duct formed by a tube 30 which extends through the pad, to terminate at the leading surface 26 of the pad, which leading surface 26 is closest to the power head 16. Irrigation fluid may be supplied by manual or powered means through the tube 30. With this arrangement, the irrigation fluid is supplied directly to the region where cutting or drilling occurs, and the direction of the flow of the irrigation fluid may be controlled by controlling the orientation of the tool. A further modification is illustrated in Figs. 4a to 4d. The pad 20 illustrated in Figs. 4a to 4d is generally similar to the pad of Figs. 2a to 2f, and the same reference numerals are used. However, in this arrangement an onlay 40 is positioned on the inner surface 24 of the pad 20. The onlay is of acrylnitrite butadiene styrene [ABS] and provides additional vibration absorption.

Note that the arrangements of Figs. 4a to 4d may be combined with the arrangements of Figs. 3a and 3b, so the pad has both an irrigation duct and an onlay.

Fig. 5 illustrates how the tool may have a further pad 50 (VM-G pad) mounted on the handle 12. Note that the pad 20 is not shown in Fig. 5, but may be used in an embodiment having two pads .

The pad 50 shown in Fig. 5 is illustrated in more detail in Figs. 6a to 6d. As this can be seen, it is generally shaped to fit the handle 12, and has a projection part 52 which conforms to the surgeon's hand. A slit 54 in the pad 50 enables it to be fitted around the handle 12. There may be an onlay 56 in a surface of the pad. Again, the onlay 56 is made of ABS. A modification of the further pad 50 (VM-G pad) is shown in Figs. 7 and 8a to 8d. It has been found that significant vibration is transmitted via trigger 18 to the user's hand and it is desirable to interpose the material of the pad between that trigger 18 and the user's finger which activates the trigger 18.

Thus, as shown in Fig. 7, the front of the further pad 50 has an extension 60 which covers the trigger 18 and extends to make contact with the surface 62 of the body 10 of the tool immediately above the trigger 18. Furthermore, as can be seen in Fig. 8a, the extension 60 passes around both sides of the trigger 18, so that no part of the trigger 18 can come into contact with the user's hand, and vibrations are thus absorbed.

It can also be seen that, in this modification, the slit 54 is at the back of the pad 50 remote from the extension 60, as it not desirable to have any gap in the extension 60 at the front of the pad. The onlay 56 is also moved to the inner front of the pad.

It may be noted that this arrangement, in which the onlay 56 is at the front and the slit 54 is at the back may also be used with the arrangement of Figs. 5 and 6a to 6d.

Claims

1. A hand-held surgical tool having at least one pad of vibration-absorbent material thereon, the pad being of hydrophobic polyurethane foam made from a polyol and isocyanate composition in which the weight ratio of polyol to isocyanate is from 2.5:1 to 1.5:1.

2. A tool according to claim 1, which tool is a saw having a handle being a first hand grip and an elongate surface being a second hand grip.

3. A tool according to claim 2, which is also adopted for bone drilling.

4. A tool according to claim 2 or claim 3, wherein the at least one pad of vibration absorbent material comprises a first pad mounted on the second hand grip.

5. A tool according to claim 4, having a first onlay between the first pad and the second hand grip, the onlay being of acrylonitrile butadiene styrene [ABS].

6. A tool according to claim 4 or claim 5, wherein the weight ratio of the polyol to isocyanate of the first pad is from 8.5:3.9 to 9:5.

7. A tool according to any one of claims 4 to 6, further including an irrigation duct through the first pad.

8. A tool according to claim 2 or claim 3 wherein the at least one pad of vibration absorbent material comprises a second pad mounted on the first hand grip.

9. A tool according to claim 8, wherein the handle has a trigger extending therefrom for controlling the operation of the tool, and the second pad covers the trigger.

10. A tool according to claim 8 or claim 9, having a second onlay between the second pad and the rest of the tool, the onlay is of acrylonitrile butadiene styrene [ABS].

11. A tool according to any one of claims 8 to 10, wherein the weight ratio of the polyol to isocyanate of the second pad is from 15:6.8 to 12:6.7.

12. A tool according to any one of the claims, wherein, in the polyol and isocyanate composition that forms the at least one pad: (i) the polyol comprises 94.8% by weight polyoxyalkylene triols, 1.8% by weight triethanolamine, 0.2% by weight dipropylene glycol, 0.1% by weight triethyldiamine, 0.4% by weight organo-modified polysiloxanes, 2.1% by weight C9-11 alcohol ethoxylate and 0.6% by weight 2 —[ [2 — dimethylamino) ethyl]methylamino] ethanol, and/or (ii) the isocyanate comprises 50% to 77% by weight diphenylmethanediisocyanate, isomers and homologues thereof, and 23% to 50% by weight isocyanates that are the reaction product of the polyol with methylenediphenyldiisocyanate.

13. A hand-held surgical tool having at least one pad of vibration-absorbent material thereon, the pad having an irrigation duct therethrough connected to means for supplying irrigation fluid to the duct.

14. A tool according to claim 7 or claim 12 wherein the irrigation duct terminates at an outer surface of said pad or said first pad.

15. A pad for a hand-held surgical tool, the pad being of hydrophobic polyurethane foam made from a polyol and isocyanate composition in which the weight ratio of polyol to isocyanate is from 2.5:1 to 1.5:1.

16. A pad according to claim 12 wherein the weight ratio of the polyol to isocyanate is from 8.5:3.9 to 9:5 and 15:6.8 to 12:6.7.

17. A pad for a hand-held surgical tool, wherein the pad has an irrigation duct therethrough connected to means for supplying irrigation fluid to the duct.