Abstract:
A device for applying traction to the cervical vertebrae to reduce fracture dislocation of the cervical spine, said device including: a support surface adapted to support a patient lying upon his or her back; a load transmitting means adapted to be connected at one end to a patient under treatment and lying upon said support surface; the other end of said load transmitting means being adapted to be connected to a load applying means; said load applying means being movable along a regular or irregular curve to any of a range of predetermined positions between a first position which places the patient&#39;s cervical spine in flexion and a second position which places the patient&#39;s cervical spine in extension.

Description:
FIELD OF INVENTION 
       [0001]    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 
       [0002]    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. 
         [0003]    Spinal cord trauma can be caused by a wide range of injuries to the spine, resulting from, for example, 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 side of the trauma, and thus can affect the arms and legs, as well as causing breathing difficulties. Spinal cord trauma affecting cervical vertebra is a distressingly common result of motor vehicle accidents, rugby accidents and diving accidents caused by diving into shallow water. 
         [0004]    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. 
         [0005]    It has been found that rapid treatment (preferably within four hours or less of the accident) can be particularly effective in the case of low velocity injuries to the cervical vertebrae. Typically, low velocity injuries are caused by sports accidents, e.g. accidents during rugby, or trampolining or wrestling or gymnastics. Low velocity injuries typically cause damage in the form of a kink in the spinal cord, but the damage is at a sufficiently low level that if traction can be applied rapidly, soon after the injury, it is possible to achieve a complete, or almost complete, recovery. 
         [0006]    Over the last several centuries, a number of devices have been proposed to apply traction to the spine. Many of the devices for this purpose are essentially physiotherapy devices, which are designed simply to apply a lower level of traction to various parts of the spine, as part of a regular physiotherapy treatment, or to relieve relatively mild discomfort, as opposed to applying traction specifically to realign damaged cervical vertebrae. 
         [0007]    For applying traction for medical treatment purposes, the most commonly used medical apparatus involves an arcuate harness which is secured to the patient&#39;s skull and connected to one end of a rope, the other of which passes over a pulley and carries weights. The weights are loaded onto a hangar and can be increased or decreased as necessary. 
         [0008]    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 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 further drawback is that it is not possible to vary the angle at which the weights are applied to the patient. 
         [0009]    A number of devices have been proposed, which avoid the use of free hanging weights—see for example U.S. Pat. No. 6,984,217. However, none of the existing devices for applying traction allow traction to be applied through a wide angular range, so that the traction can not only be applied along a neutral line, (i.e. approximately in line with the undamaged portion of the spine), but can also be applied from above the patient so as to place the spine in flexion (i.e. forward bend), and below the patient, so as to place the spine in extension (i.e. backward bend. 
       SUMMARY OF THE INVENTION 
       [0010]    An object of the present invention is the provision of a traction device suitable for applying traction to the cervical vertebrae, which allows traction to be applied through a sufficiently wide angular range so as to place the spine in flexion or in extension or in any of a range of preselected positions between these two extremes. 
         [0011]    The present invention provides a device for applying traction to the cervical vertebra to reduce fracture dislocation of the cervical spine, said device including: 
         [0012]    a support surface adapted to support a patient lying upon his or her back; 
         [0013]    a load transmitting means adapted to be connected at one end to a patient under treatment and lying upon said support surface; 
         [0014]    the other end of said load transmitting means being adapted to be connected to a load applying means; 
         [0015]    said load applying means being movable along a regular or irregular curve to any of a range of predetermined positions between a first position which places the patient&#39;s cervical spine in flexion and a second position which places the patient&#39;s cervical spine in extension. 
         [0016]    In a preferred embodiment of the present invention, the load applying means is mounted upon a support which is in the shape of a regular or irregular curve and which is adapted to be moved relative to said support surface so as to move said load applying means between said first and second positions. The support may be formed as a gear rack which is adapted to be moved relative to said support by means of a pinion connected to said support surface. 
         [0017]    Another possibility is to mount said load applying means upon a support in the shape of a regular or irregular curve, said load applying means being adapted to move relative to said support, between said first and second positions. 
         [0018]    Preferably, the angle between said first and second positions is at least 90°. 
         [0019]    The curve through which the load applying means can be moved may be a regular or irregular curve, but preferably is a regular curve formed as an arc of a circle with a radius of about 650 mm. 
         [0020]    Any suitable load applying means may be used. 
         [0021]    The load transmitting means may be any suitable rigid, semirigid or flexible load transmitting means. Preferably, however, the load transmitting means is flexible, e.g. a wire or a wire rope, used in conjunction with a load applying means in the form of a winch which provides a winch drum around which the load transmitting means is wound. 
         [0022]    Preferably, the support surface is adapted to be tiltable between a base position in which the plane of the support surface is substantially horizontal and a tilted position in which the plane of the support surface is at at least 45° to the horizontal, and to any of a range of predetermined positions between said base and said tilted positions. 
         [0023]    The actual load to be applied to the patient depends 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 2 kg to 50 kg. 
         [0024]    Preferably, the device includes a load measuring means arranged such that in use the load measuring means reads the load on said load transmitting means. The load measuring means may be any suitable measuring device capable of accurate measurement, and preferably is a load cell. The load measuring means may be mounted adjacent 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. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    By way of example only, a preferred embodiment of the present invention is described in detail, with reference to the attached drawings, in which:— 
           [0026]      FIG. 1  is a diagrammatic side view of a support surface and a traction device in accordance with the present invention, showing the application of neutral traction; 
           [0027]      FIG. 2  is a view similar to  FIG. 1 , but with the support surface tilted; 
           [0028]      FIG. 3  is a view similar to  FIG. 2 , with the traction device applying maximum flexion; 
           [0029]      FIG. 4  is a view similar to  FIG. 1 , but with the traction device applying maximum extension; 
           [0030]      FIG. 5  is a view of part of the traction device, on a larger scale, with the rack and pinion shown straight rather than curved, for clarity; 
           [0031]      FIG. 6  is a side view of the load applying means; and 
           [0032]      FIG. 7  is a plan view of the load applying means. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0033]    Referring to the drawings, as shown in  FIGS. 1-4 , a patient  10  to be treated for fracture dislocations of the cervical spine is supported upon a support surface  11  in the form of a Howard Wright trauma stretcher. The trauma stretcher is of known type, and provides a mattress  12  carried upon a mobile base  13  which can be adjusted in angle (see  FIGS. 2 and 3 ). The base  13  can be tilted from the ‘base’ position shown in 
         [0034]      FIG. 1 , in which the plane of the base is substantially horizontal, up to a position in which the plane of the base is at about 25° to the horizontal, or even up to 45°. The base  13  also may be tilted to any of a range of positions between these extremes. The stretcher also provides means for securing the patient to the stretcher, so that traction can be applied as described below without actually pulling the patient along the stretcher. 
         [0035]    For clarity, in the drawings the head of the patient  10  is shown unsupported, with the patient&#39;s shoulders aligned with the end of the mattress; in practice the patient&#39;s head is supported by a pillow. 
         [0036]    A flexible load transmitting means  14 , in the form of a wire rope, is connected at one end to the patient  10  by Gardner Wells tongs  15 . The tongs are of known design, and the free ends of the tongs are connected directly into a patient&#39;s skull. 
         [0037]    The other end of the wire rope  14  is wound around the drum  16  of a load applying means in the form of a winch  17  (see  FIGS. 6 and 7 ). 
         [0038]    The winch  17  is mounted at one end of a curved support  18  which forms the rack of a rack and pinion drive, the pinion  19  being rigidly secured to the midpoint of the end of the trauma stretcher  11 , adjacent the head of a patient  10  in use, by means of a bracket  20  and a clamp  21 . 
         [0039]    It is important that the length of the bracket  20  is sufficient to space the device from the head of the stretcher:—there must be room for the rack  18  to move relative to the pinion whilst remaining clear of the stretcher, and the length of the wire  14  between the patient and the winch should be at least 300 mm at the start of the procedure, to allow adequate scope for increasing the tension as necessary. 
         [0040]    The pinion  19  is curved to match the curve of the rack  18 . The rack  18  is shown as a smooth, arcuate, curve, but may in fact be formed as any of a range of regular or irregular curves, and preferably is formed as a C shape. Forming the rack  18  as a smooth arc with a radius of about 650 mm has been found to work well in practice. In practical terms, the radius of the curve of the rack  18  (if regular) or the shape of the rack  18  (if irregular) must be such that the load applying means can be positioned to apply everything from a maximum extension load, through a neutral load, to a maximum flexion load to a patient, but such that the rack  18  does not contact the floor or the stretcher in any position; and preferably such that the rack  18  is not inconveniently high above the stretcher either. Within these practical limits, the radius and shape of the curve of the rack may be varied as required. 
         [0041]    The above described arrangement of means that the angle at which traction is applied to a patient can be varied by moving the rack  18  relative to the pinion  19  to raise or lower the winch  17  relative to a patient supported upon the stretcher, and the angle can also be varied by tilting the stretcher, as shown in  FIGS. 2 and 3 . 
         [0042]    The degree of traction applied to a patient can be increased or decreased by winding more or less of the wire rope  14  around the drum  16  of the winch  17 , but also can be varied by varying the angle at which the traction is applied:—increasing the angle at which traction is applied will not only increase the degree of flexion of the cervical vertebrae, but also increase the load applied. Conversely, decreasing the angle at which traction is applied will decrease the degree of flexion, and if the neutral point has been passed, (i.e. where the load is applied aligned with the undamaged portion of the patient&#39;s spine) will increase the extension, and will also increase the load applied. 
         [0043]      FIG. 5  shows a detail of the rack and pinion, but with both the rack and the pinion shown straight rather than curved, for clarity. The rack  18  is formed along the whole of its length as a gear rack which engages with a pinion  19  mounted inside a mounting box  23 . The pinion  19  can be rotated by means of a handle  24  via a right angle geared worms/worm wheel drive (not shown) of known type. Preferably, the gear ratio is 40:1, so that very fine adjustments can be provided by rotating the handle. It would of course be possible to drive the pinion using motorised drive means, if preferred. 
         [0044]    Thus, rotating the handle  24  moves the rack  18  up or down relative to the pinion  19 , depending upon the direction of rotation of the handle. 
         [0045]      FIGS. 6 and 7  show the winch  17  in greater detail. The winch  17  is carried on a plate  25 , which also supports a load cell  26  as described below. The underside of the plate  25  is secured to the upper end of the track  18  such that in the neutral position shown in  FIG. 1 , the plane of the plate  25  is substantially horizontal. 
         [0046]    The winch  17  is a small geared winch powered by a winding handle  27  which can be manually rotated to rotate the winch drum  16  around an axle  16   a , via a right angle geared drive (not visible) mounted below the winch drum  16 . Preferably the gear ratio is 30:1 so that very small movements of the winch wire  14  are possible. The winch  17  could be driven by a motor if preferred. 
         [0047]    One end of the wire rope  14  is permanently secured to the drum  16 ; the winch wire  14  passes from the drum  16 , between a freely rotatable guide pulley  28  and a peg  29 , and over a second free rotatable guide pulley  30  which directs the winch wire  14  outwards to hook onto the Gardner Wells tongs  15  secured to the patient, by means of a hook  31  secured to the free end of the wire rope. 
         [0048]    One side of the winch  17  is mounted on an angled plate  32  which is bent through a right angle. The other side of the plate  32  is apertured to receive a bolt  33  which provides a load transmitting connection to the load cell  26 . The other end of the load cell  26  is anchored by means of a bolt  34  to the plate  25 . The winch  17  and plate  32  can slide relative to the plate  25 , so that the load on the wire rope  14 , which is of course transmitted to the winch drum  16 , is recorded by the load cell  26 . Thus, as the handle  27  of the winch is rotated in either direction, the increase or decrease of the load on the wire  14  can be read directly from the display  35  of the load cell  26 . 
         [0049]    The above described device is used as shown in  FIGS. 1-4 . The patient  10  lies on the stretcher  11  and is secured using known means (not shown). A Gardner Wells tongs  15  is connected to the patient&#39;s skull in known manner, and the wire rope  14  from the winch  17  is hooked onto the tongs  15  by the hook  31 . 
         [0050]    In the position shown in  FIG. 1 , the stretcher  11  provides a support surface in the horizontal plane, and the rack  18  is positioned so that the winch  17  is approximately opposite the end of the patient&#39;s spine. This means that the wire rope  14 , when tensioned by the winch  17 , applies a neutral traction to the patient, i.e. in a direction aligned with the undamaged portion of the patient&#39;s spine. 
         [0051]    The objective of the traction is to rapidly but gently reduce any distortion of the spinal cord, to remove abnormal pressure from the spinal cord, and to realign any displaced portions of the spine. 
         [0052]    In the neutral position shown in  FIG. 1 , the winch wire is used to apply a loading of (typically) 2 to 2.5 kg. X-rays normally are taken before starting treatment, and also taken at every stage during treatment with the device:—the patient is x-rayed after every five kg increase in loading. 
         [0053]    In the next stage of treatment, the leg end of the stretcher  11  is lowered to an angle of about 16° to the horizontal, as shown in  FIG. 2 . This maintains a straight, (i.e. neutral) traction on the patient, but increases the load applied to the patient, e.g. to 5 kg. The rack  18  is then slowly moved relative to the pinion  19 , using the hand wheel  24 , to raise the winch  17  to the position shown in  FIG. 3  thus gradually increasing the flexion of the cervical spine, to realign that portion of the spinal cord to the correct alignment. The full limit of maximum flexion is when the patient&#39;s chin contacts his or her chest. If necessary, the load applied by the winch  17  may be raised during this stage, e.g. to 15 kg. 
         [0054]    In general, increasing the angle of the load increases the degree of flexion of the cervical vertebrae and also increases the load applied. Decreasing the angle of the load decreases the degree of flexion and also decreases the load applied, until the neutral loading point has been passed, as described above. 
         [0055]    It will be appreciated that the degree of loading, and the angle at which the traction is applied, both are varied depending upon the patient&#39;s size and weight and the degree and type of damage to the spine:—a constant monitoring of the treatment by means of x-rays of the cervical spine area are needed to make sure that both the traction and the degree of flexion or extension are kept to the minimum needed for the desired effect. 
         [0056]    When the x-rays indicate that the dislocated vertebra(e) has been correctly reduced, i.e. realigned, the stretcher  11  is gradually moved back to the horizontal position shown in  FIG. 4 , and the angle of traction is gradually reversed to place the cervical spine in extension rather than flexion:—this means that the winch  17  is actually at a level below the patient&#39;s head, as shown in  FIG. 4 . Maintaining the cervical spine in extension, at a relatively low traction loading, maintains the reduction of the spine without over distracting the spine. When the spine is in extension, typically the loading in kilograms applied by the winch is the same as the number of the vertebra at the break—C5 break has a 5 kg loading, C4 break has a 4 kg loading, and so on.