Field of the Invention

The present invention relates to a traction device, and in particular to a device for applying traction to the cervical vertebrae, and reducing fracture dislocations of the cervical spine.

Background of the Invention

Any discussion of the prior art throughout the specification is not an admission that such prior art is widely known or forms part of the common general knowledge in the field.

Spinal cord trauma can be caused by a wide range of injuries to the spine, resulting from (e.g.) motor vehicle accidents, falls, and sports injuries. Spinal cord trauma affecting the cervical vertebrae (i.e. C1 - C7 vertebrae) can be especially serious, in that it affects everything below the site of the trauma, and thus can affect the arms and the legs, as well as causing breathing difficulties. Spinal cord trauma affecting the cervical vertebrae is a distressingly common result of motor vehicle accidents, rugby accidents and diving accidents caused by diving into shallow water.

In all cases of spinal cord trauma, rapid treatment is necessary to reduce the long-term effects; the treatment usually includes spinal traction to reduce dislocation and produce the necessary anatomic realignment. Surgery also is necessary in some cases.

Over the last several centuries, a wide variety of devices have been used to apply traction, especially to reduce dislocation of the cervical vertebrae. At present, the most commonly used arrangement is an arcuate harness secured to the patient's skull and connected to one end of a rope, the other end which passes over a pulley and carries weights. The weights are loaded on to a hangar and can be increased or decreased as necessary.

This arrangement has the merit of being relatively inexpensive, and simple to use. However, in this arrangement the weights hang freely near the end of the bed on which the patient is supported, and are vulnerable to being knocked against and displaced. Further, once traction has been applied, the patient cannot be moved whilst under traction. Another drawback is that the force applied by the traction cannot be increased gradually but only in set increments depending upon the size of the weights being applied.

A number of devices for applying traction which do not involve the use of free hanging weights have been proposed e.g. US 5,451 ,202 and US 4,890,605. However, both of these devices have the disadvantage that, although the angle at which tension is applied can be varied, it cannot be varied whilst the tension is actually being applied; the ability to do this can be important for effective treatment, as maximum flexion of the cervical vertebrae can be achieved with weights on, allowing for easier reduction.

Summary of the Invention

An object of the present invention is the provision of a traction device suitable for applying traction to the cervical vertebrae, which allows the angle at which the tension is applied to be varied whilst the tension is being applied.

The present invention provides a device for applying traction to the cervical vertebrae, said device including:

- a load applying means mounted upon a support ;

- a flexible load transmitting means adapted to be connected at one end to a patient under treatment and at the other end to the load applying means;

- a load measuring means arranged such that in use the load measuring means reads the load on said flexible load transmitting means;

- adjustment means for adjusting the height of said support and said load applying means, so as to adjust the angle at which load is applied to a patient in use; said adjustment means being such height adjustment may be made while the load applying means is in use.

The load applying means may be any suitable means capable of applying consistent and stable loading to the flexible load transmitting means. Suitable load applying means include: a winch providing a winch drum around which the flexible load transmitting means is wound; a hydraulic ram; a screw tensioner. The actual load to be applied to the patient varies depending upon a number of factors, which include the type of treatment being used, the weight of the patient, and the angle at which the load is to be applied. Typical loads are in the range 3 kg - 50 kg.

Preferably, the flexible load transmitting means is a wire; as used herein, the term "wire" includes a wire rope.

Preferably, the load applying means is a winch and the flexible load transmitting means is a winch wire wound around the winch drum.

The load measuring means may be any suitable measuring device capable of accurate measurement. Preferably, the measuring means is a load cell.

The load measuring means preferably is mounted on the support connected to the load applying means, but could be incorporated in the load transmitting means or connected between the load transmitting means and the load applying means.

The adjustment means for adjusting the height of the support may be any suitable means capable of providing very small and accurate adjustment of position, without any appreciable slack or play in the system. Suitable adjustment means include a rack and pinion adjustment means, a hydraulic ram, or a screw threaded adjustment means.

It will be appreciated that adjusting the height of the support and the load applying means adjusts the angle at which load is applied to a patient under treatment, because the height of the support and the load applying means controls the angle of the flexible load transmitting means which extends between the load applying means and the patient. It is advantageous to be able to vary the angle of load applied to the patient over a wide range, e.g. from 0° (that is, a substantially straight line pull) up to about 80° to the horizontal, assuming of course that the patient is being supported on a substantially horizontal surface. Increasing the angle of the load applied to the patient increases the degree of flexion of the cervical vertebrae. In general, the greater the degree of flexion, the lower the load applied, but it will be appreciated that both the load to be applied and the angle at which the load to be applied is a matter for selection by the doctor controlling the treatment, on a case by case basis. Preferably, the adjustment means for adjusting the height of the support is a rack and pinion arrangement, with the rack formed along the length of a post which carries the support, and the pinion movable through a geared drive.

Brief Description of the Drawings

By way of example only, preferred embodiments of the present invention are described in detail, with reference to the attached drawings in which:- Figure 1 is a side view of apparatus in accordance with the present invention;

Figure 2 is a plan view of the upper part of the apparatus of Figure 1 , on a larger scale; Figures 2a and 2b are views similar to Figure 2, but showing other embodiments; Figure 3 is a side view of part of the apparatus of Figure 1 , on a larger scale;

Figures 3a and 3b are views similar to Figure 3, but showing other embodiments; and Figure 4 is a diagrammatic sketch showing the apparatus of Figure 1 in use.

Detailed Description of Preferred Embodiment

Referring to the drawings, a device 10 for applying traction includes a post 1 1 , a height adjuster 12, a load applying means in the form of a winch 13, and a load cell 14. The device 10 is mounted on a convenient support (for example the bed frame of a bed upon which the patient is supported) by means of a bracket 15 which is U-shaped in cross-section and which is hooked over a horizontal bed frame member (not shown) and secured by a manually adjustable clamp 16. The bracket 15 is rigidly secured to one side of the height adjuster 12.

The height adjuster 12 is shown in greater detail in Figure 3 and consists of a hollow rectangular cross-section mounting box 17 which has two spaced parallel sides 18 arranged one on each side of the support post 1 1 , and a pair of spaced parallel end plates 18a. The post 1 1 extends right through the mounting box 17 and projects below the open end of the box. The post 1 1 is guided within the mounting box 17 by two pairs of freely rotatable spaced guide rollers 19,20, which lightly engage the front and rear surfaces of the post 1 1. As shown in Figure 3, the full length of the front surface of the post 1 1 is formed as a gear rack 21 ; this engages with a pinion 22 mounted inside the mounting box 17 which is rotatable by means of the handle 23 via a right angle geared worm/worm wheel drive 24 (indicated in broken lines). Thus, manual rotation of the handle 23 moves the post 1 1 up or down relative to the mounting box 17; the winch 13 and load cell 14 move with the post 1 1 , as described below. Preferably, the gear ratio is 40: 1 , to provide very fine adjustments.

The other end of the post 11 carries a support in the form of a plate 30 on the upper surface of which the winch 13 and load cell 14 are mounted. The plane of the plate 30 is at an acute angle to the horizontal, and is inclined downwards relative to the end of the device nearest to the patient.

The winch 13 is a small geared winch powered by a winding handle 31 which can be manually rotated to rotate a winch drum 32 around an axle 32a, via a right angle geared drive (not visible) mounted below the winch drum 32. Preferably the gear ratio is 30: 1 so that very small movements of the winch wire 33 are possible. One end of a flexible load transmitting means in the form of a winch wire 33 is permanently secured to the drum 32. The winch wire 33 passes from the drum 32 between a first freely rotatable guide pulley 34 and a guide peg 35 and over a second freely rotatable guide pulley 36, which directs the winch wire 33 outwards and downwards towards the patient. The free end of the winch wire 33 (shown only in Figure 4) is fitted with a hook which hooks onto a head harness attached to the patient. Typically, the head harness is the well-known Gardner-Wells harness.

One side of the winch 13 is mounted on one side of a right angle plate 38; the other side of the plate 38 is apertured, and the aperture receives a bolt 40 which provides a load-transmitting connection to the load cell 14. The other end of the load cell 14 is anchored by means of a bolt 41 to the lower end of the plate 30. The winch 13 and the plate 38 can slide relative to the plate 30, so that the load on the wire 33, which is of course transmitted to the winch drum 32, is recorded by the load cell 14. Thus, as the handle 31 of the winch is rotated in either direction the increase or decrease of the load on the wire 33 can be read directly from the display 42 of the load cell 14.

The above described device is used as shown in Figure 4:- a patient 45 to be treated lies on a bed 46, and is if necessary is restrained to enable the required amount of traction to be applied. An arcuate Gardner-Wells harness 47 is secured to the patient's head, by inserting securing screws 48 into the patient's skull. The angle of traction to be applied to the patient is adjusted simply by rotating the handle 23 of the rack and pinion drive to move the post 1 1 up or down as necessary. The hook (not shown) at the free end of the wire 33 is then hooked on to the centre of the harness 47, and the handle 31 is rotated to wind the wire 33 around the winch drum 32 until the load cell 14 indicates that the required amount of traction is being applied to the patient.

If it is necessary to adjust the angle at which traction is applied during treatment, the post is raised or lowered as necessary. The rack and pinion drive on the post 1 1 enables very small adjustments of position to be made, and there is no slack in the adjustment; this enables very accurate control of the angle.

For some patients, it can be very important to be able to adjust the angle at which traction is applied, without any reduction in the degree of traction or even removal of the traction. For such patients, the ability of the device of the present invention to provide a smooth alteration in the angle of applied traction while still maintaining the required load on the patient, is extremely valuable.

The geared drive to the winch drum 32 enables the traction applied to the patient to be increased or decreased by very small amounts if necessary, and the arrangement gives a very positive control of the traction, since over the short length of the wire 33, the wire can be regarded as virtually inelastic.

Both the winch 13 and the rack and pinion drive for adjusting the height of post 1 1 could be driven by one or more suitable motors rather than by manual winding handles.

The above described device may be varied in a number of ways without departing from the scope of the invention. For example, the load applying means could be a hydraulic ram 50 as shown in Figure 2a. In this variant, one end of the wire 33 is secured to the outer end 51 of the piston, and the end 52 of the cylinder is secured to the face 38a of the plate 38, to provide a load transmitting connection to the load cell 14, via the bolt 40. The other end of the wire 33 is secured to the harness 47, as described above. The hydraulic hoses are omitted from Figure 2a for clarity. This variant operates in the same manner as described above, except that load is applied to the wire 33 by retracting the piston 51 of the hydraulic ram 50. Another variant is illustrated in Figure 2b, in which a screw tensioner 55 is substituted for the winch. The screw tensioner consists of a casing 56 and two screws 57,58 which are respectively right-hand and left-hand threaded. The casing 56 is internally screw threaded; one end 56a is right-hand threaded and is engaged with one end of screw 57; the other end 56b is left-hand threaded and is engaged with one end of screw 58. The casing 56 may be rotated manually or by a motor, either directly or via geared connection.

The end of the screw 57 remote from the casing 56 is secured to the face 38a of the plate 38, to provide a load transmitting connection to the load cell 14, via the bolt 40. The end of the screw 58 remote from the casing 56 is secured to one end of a wire 33, the other end of which is secured to the harness 47 as described above.

Rotation of the casing 56 in a first direction extends the screws 57,58 outwards from the casing 56; rotation of the casing 56 in the opposite direction retract the screws 57,58 into the casing. Both screws 57,58 are keyed (not shown) to the casing to ensure that the motion of the screws 57,58 relative to the casing 56, is linear. Extension of the screws 57,58 relative to the casing 56 reduces the load on the wire 33, and retraction of the screws 57,58 into the casing increases the load on the wire 33. If the screw threads selected for the casing 56 and the screws 57,58 are fine, very precise adjustment of the load on the wire 33 is possible.

In all of the arrangements described above, it will be appreciated that the load applying means is substantially stationary relative to the load transmitting means, once the selected load has been applied. This has the advantage that, if the harness 47 slips on the patient's head (generally because one of the securing screws becomes loose), there is effectively no load on the wire 33, and screws are not dragged along the patient's head under load. Securing screws seldom become loose, but it does happen occasionally, and with the older apparatus which used free hanging weights, one or more of the loosened screws could be dragged across the patient's scalp, causing injury.

Another possible variant of the above described device uses a load applying means capable of delivering a static pull. With this arrangement, the load cell is electronically connected to control a motorised load applying means, such that any fluctuation in the applied load recorded by the load cell is automatically compensated for. This has the advantage of automatically compensating for fluctuations in load caused, for example, by movement of the patient. However, it has the disadvantage that if the securing screws of the harness become loose, load will continue to be applied to the wire, with a corresponding risk of injury to the patient.

A further possible variant of the above described device is to use a different type of adjustment means for adjusting the height of the support. Any of a range of adjustment means capable of accurate adjustment can be used. Two possible variants are shown in Figures 3a and b.

In the variant shown in Figure 3a, the height adjuster 12 consists of a hydraulic ram 60 operated by a conventional hydraulic controls (not shown). The outer end 61 of the piston 62 carries the plate 30. The ram 60 is rigidly secured to a mounting bracket 15 which can be secured by a manually adjustable clamp 16, as described above. The height of the plate 30 is adjusted by extending or retracting the piston 62 of the ram 60.

In the variant shown in Figure 3b, the height adjuster 12 consists of a screw adjuster 70 with the plate 30 mounted on the upper end of the screw 71. The screw adjuster 70 consists of a U-shaped housing 72 which provides two parallel opposed limbs 73,74, each of which is formed with an aligned keyed aperture through which the externally screw threaded screw 71 passes. The screw 71 is formed with a corresponding keyway 76 to ensure the motion of the screw relative to the housing 72 is linear.

Between the limbs 73,74 is mounted an internally screw threaded housing 75 which is engaged with the screw 71. Rotation of the housing 75 in one direction raises the screw 71 ; rotation of the housing 75 in the opposite direction lowers the screw 71. The housing 75 may be rotated manually or via a motor (not shown).

Any of the different height adjusters described with reference to Figures 3, 3a and b may be used with any of the above described load applying means.

It will be appreciated that, the device of the present invention is completely supported upon the bed frame, and does not include any parts which can be knocked loose or adjusted accidentally, so that a patient can be moved on the bed whilst traction is being applied, without any risk of accidental increase or reduction in traction. It is envisaged that provision may be made for locking the position of any winding handles as a further precaution during movement.