Abstract:
A guard for a cast cutter includes a first member securable to a cast cutter and a second member securable to a guard member. The second member is freely movable relative to the first member during operation along a support axis. Stops limiting movement in either direction along the support axis. This cast cutter guard has only one setting which accommodates variations thickness. Pressure exerted upon the cast cutter during operation results in movement of the second member relative to the first member, rather than pressure upon the injured area.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a guard for a cast cutter and, in particular, a cast cutter that utilizes a rotary cutting blade. 
     BACKGROUND OF THE INVENTION 
     Medical staff place a cast over a broken limb of a patient to protect the area of the break and maintain proper bone positioning during healing. A layer of fabric is first placed over the patient&#39;s limb. Plaster is then placed over the layer of fabric. The plaster hardens to provide both support for the injured area and a protective layer. 
     When the cast is to be removed it must be cut away using cast cutters. A common form of cast cutter used in many hospitals uses a rotary blade. Great care must be when a rotary blade cast cutter is used. If penetration of the rotary blade is too deep, the patient will receive a cut from the blade. The blade becomes heated during cutting, so even if the blade does not cut the patient, the patient can receive a burn if the blade is brought too close to the skin. The rotary cutter blades are durable enough to withstand numerous uses. However, when the blade are used on multiple patients there is a danger that they may become instruments for the spread of infectious diseases. 
     An obvious solution to the problem of cuts from the cast cutter is to provide some form of guard. U.S. Pat. Nos. 4,625,405 and 5,020,226 both illustrate cast cutters with hook like guards that maintain a cutting blade a constant distance from a patient&#39;s skin. Due to some inherent disadvantages, these types of guards have not gained favour with medical staff. One disadvantage is that casts come in a variety of thicknesses. As a result, there is a need to adjust the depth of the guard from cast to cast, which is time consuming. Another disadvantage is that casts tend to be irregular in thickness. As a result there is a need to adjust the depth of the guard during the cutting of the cast. A further problem is that the guard tends to exert pressure upon the injured area. This causes the patient discomfort, especially when the cast is being cut in the proximity of stitches or sutures. 
     SUMMARY OF THE INVENTION 
     What is required is an alternative configuration of guard for a cast cutter. 
     According to one aspect of the present invention there is provided a guard for a cast cutter which includes a first member securable to a cast cutter and a second member securable to a guard member. The second member is freely movable relative to the first member during operation along a support axis. A first stop limits movement of the second member toward the first member along the support axis. A second stop limits movement of the second member away from the first member along the support axis. 
     The cast cutter guard, as described above, overcomes the disadvantages inherent in prior art cast cutter guards. The second member moves freely relative to the first member along the support axis during operation. This provides an advantage to medical staff, as the cast cutter guard has only one setting, which accommodates any thickness of cast as well as variations in the thickness of an individual cast. This provides an advantage to the patient, as the pressure exerted by the medical staff upon the cast cutter translates into movement of the second member relative to the first member; rather than pressure upon the injured area. 
     Once the teaching of the present invention of free movement of second member relative to the first member, rather than fixed guard positioning, is understood; there are a number of different physical structures to apply this teaching. The cast cutter guard that will hereinafter be described is merely a preferred one of a number of alternative configurations. 
     Once the teachings of the present invention are understood, it is possible for a manufacturer of a cast cutter to build this form of cast cutter guard into the cast cutter during manufacture. According to another aspect of the invention there is provided a combination of a cast cutter with a cast cutter guard. As this type of cast cutter guard is best suited for rotary blade cast cutters, the cast cutter includes a body with a rotary cutting blade rotating about a rotational axis. The cast cutter guard, as described above, has a first member positioned on the body of the cast cutter and a second member carrying a guard member. The second member is freely movable relative to the first member during operation along a support axis substantially perpendicular to the rotational axis. The first stop limits movement of the second member toward the first member along the support axis to maintain the guard member spaced outwardly a safe distance from a peripheral edge of the rotary cutting blade. The second stop limits movement of the second member away from the first member along the support axis to prevent separation of the second member from the first member. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features of the invention will become more apparent from the following description in which reference is made to the appended drawings, wherein: 
     FIG. 1 is a perspective view of a cast cutter guard constructed in accordance with the teachings of the present invention positioned on a rotary blade cast cutter. 
     FIG. 2 is a front elevation view of the cast cutter guard positioned on the rotary blade cast cutter illustrated in FIG.  1 . 
     FIG. 3 is a rear elevation view of the cast cutter guard positioned on the rotary blade cast cutter illustrated in FIG.  1 . 
     FIG. 4 is a detailed end elevation view of the cast cutter guard positioned on the rotary blade cast cutter illustrated in FIG. 1, with second member a maximum distance from the first member as determined by the second stop. 
     FIG. 5 is a detailed end elevation view of the cast cutter guard positioned on the rotary blade cast cutter illustrated in FIG. 1, with second member a minimum distance from the first member as determined by the first stop. 
     FIG. 6 is a detailed rear elevation view of the first stop and the second stop of the cast cutter guard as illustrated in FIG.  4 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The preferred embodiment, a guard for a cast cutter generally identified by reference numeral  10 , will now be described with reference to FIGS. 1 through 6. 
     Referring to FIG. 1, cast cutter guard  10  includes a first member  12  and a second member  14 . Referring to FIG. 6, first member  12  has a peripheral sidewall  16 , a first end  18 , and a second end  20 . An interior bore  22  extends between first end  18  and second end  20 . A pair of opposed guide slots  24  extend through peripheral sidewall  16  to interior bore  22 . Each of guide slots  24  has a first end  26  and a second end  28 . Referring to FIG. 1, a mounting bracket, generally indicated by reference numeral  30 , is attached to first member  12  by a mounting rod  31 , whereby first member  12  is securable to a cast cutter  32 . Mounting bracket  30  has two bands  29  which clamp around cast cutter  32 . Mounting rod  31  passes through friction fitting apertures  33  on bands  29  of mounting bracket  30 . Mounting rod  31  is telescopically movable relative to mounting bracket  30 , in order to adapt to various makes and models of cast cutter  32 . 
     “J” shaped second member  14  has a first end  34  and a second end  36 . First end  34  is telescopically received in interior bore  22  of first member  12 . Second end  36  of second member  14  serves as a guard member. Second member  14  has opposed radial pins  38  that engage guide slots  24  of first member  12 . Second member  14  is freely movable relative to first member  12  during operation along a support axis defined by interior bore  22  of first member  12 . Referring to FIG. 5, first end  26  of guide slots  24  serves as a first stop, whereby movement of second member  14  toward first member  12  along the support axis provided by interior bore  22  is limited. Referring to FIG. 4 and 6, second end  28  of guide slots  24  serves as a second stop, whereby movement of second member  14  away from first member  12  along the support axis defined by interior bore  22  is limited. A spring  40  is disposed within interior bore  22  of first member  12 . Spring  40  biases second member  14  away from first member  12 . Spring  40  has a first end  42  that bears against first end  18  of first member  12  and a second end  44  that bears against radial pins  38  of second member  14 . 
     Referring to FIGS. 1 through 6, the use and operation of cast cutter guard  10  will now be described in relation to a cast cutter  32 . Referring to FIG. 1, cast cutter  32  includes a body  46  with a rotary cutting blade  48  rotating about a rotational axis defined by a drive shaft  50 . Mounting bracket  30  is attached to cast cutter  32 . Cast cutter guard  10  as described above is attached to cast cutter  32  as will now be described. First member  12  of cast cutter guard  10  is rigidly connected to mounting rod  31 . Mounting rod  31  passes through friction fitting apertures  33  on bands  29  of mounting bracket  30 . The support axis defined by interior bore  22  of first member  12  is substantially perpendicular to the rotational axis defined by drive shaft  50 , as illustrated in FIGS. 4 and 5. Friction fitting apertures  33  permit mounting rod  31  to be moved to adjust the positioning of first member  12  relative to mounting bracket  30 . Prior to use first member  12  is moved relative to cast cutter  32  so that second member  14  is substantially coplanar with rotary cutting blade  48 , as illustrated in FIGS. 2 and 3. First stop  26  limits movement of second member  14  toward first member  12  along the support axis to maintain an inner edge  51  of guard member  14  spaced outwardly a safe distance from a peripheral edge  52  of rotary cutting blade  48 , as illustrated in FIG.  5 . Second stop  28  limits movement of second member  14  away from first member  12  along the support axis to prevent separation of second member  14  from first member  12 , as illustrated in FIG.  4 . 
     When a cast is to be cut, second end  36  of second member  14  is inserted between the cast and the patient. Cast cutter  32  is started, and peripheral edge  52  of rotary cutting blade  48  is brought into engagement with the cast by applying sufficient pressure upon cast cutter  32  to compress spring  40 . When a thicker section of the cast is engaged, the separation of peripheral edge  52  of rotary cutting blade  48  from inner edge  51  of second member  14  is initially increased by reducing the pressure on cast cutter  32 . Spring  40  expands thereby biasing second member  14  away from first member  12 . Second stop  28  prevents second member from separating from first member  12 . The separation of peripheral edge  52  of rotary cutting blade  48  from inner edge  51  of second member  14  is subsequently reduced as the thickness, or the remaining thickness, of that part of the cast is reduced. First stop  26  prevents rotary cutting blade  48  from contacting second member  14  or the patient. A distance is always maintained to avoid the patient receiving a burn as a result of heat generated by rotary cutting blade  48 . When a thinner part of the cast is to be cut, the separation of peripheral edge  52  of rotary cutting blade  48  is reduced by applying sufficient pressure on cast cutter  32  to compress spring  40  until said rotary cutting blade  48  engages the cast. Regardless of the thickness of the cast, whenever pressure is exerted to force rotary cutting blade  48  into engagement with the cast, the pressure exerted is absorbed by spring  40 . This avoids placing undue pressure upon the injured portion of the patient and, in particular, areas where there are stitches or sutures. 
     It will be apparent to one skilled in the art that the manner of relative movement of first member and second member provides numerous advantages to cast cutter guard  10 . Relative movement enables cast cutter guard  10  to accommodate any thickness of cast, and variations in thickness found within an individual cast. Relative movement means that any pressure exerted to force rotary cutting blade into cast, does not result in equal pressure being exerted by cast cutter guard  10  against the injured person. 
     It will be apparent to one skilled in the art that modifications may be made to the illustrated embodiment without departing from the spirit and scope of the invention as hereinafter defined in the claims.