as shown in the preferred embodiment of this invention , the configuration of the file assembly wherein the outer tube casing includes a solid plastic tube that describe a particular shape and number of lumens , as will be appreciated by those skilled in this surgical file instrument technology , the shape and numbers of lumen may vary without departing from the scope of this invention . the same is true for the various dimensions and angles of the file assembly which may take the form of non - angularly shaped configurations , and the size including the width and thickness will well depend on the anatomy of the patient being operated on . the types of blades of the file may be different from the one depicted in the preferred embodiment , as for example , it may include abrasive cutting surfaces instead of the micro - holes that are shown in this application . the invention can best be seen by referring to fig1 - 4 which show the surgical file instrument generally illustrated by reference numeral 10 comprising the outer split casing 12 , the s battery 14 , electric motor 16 , the motion converter 18 , and the file assembly 20 . in the assembled condition as seen in fig2 , the casing 12 is formed in two generally cylindrical members 22 and 24 that are suitably attached by the screws 26 threadably engaging the threaded lugs 28 . the terminals 30 and 32 connect the motor 16 to the battery 14 for powering the motor and driving drive shaft 34 . in turn , the drive shaft 32 provides rotary motion to the motion converter 18 , as will be to described in detail herein below . as noted in fig2 , the drive shaft 34 attaches to the coupler 36 which , in turn , is coupled to the driven shaft 38 of the planetary system 40 of the motion converter 18 for rotating the same . as will be explained below , the planetary gear system 40 rotates the cam 42 and via the follower ( see fig3 ), which , in turn , translate the drum 46 and shaft 48 to impart reciprocal motion . the file assembly 20 includes the file 50 having an angular shaft 52 , a blade 54 and tang 56 . tang 56 includes hole 58 ( see fig5 ) that cooperates with a complementary threaded hole 60 formed in the bifurcated end portion 62 ( see fig3 ) and with a suitable bolt 62 fitted into hole 58 is threaded to hole 60 connects the file 50 to drum 46 for imparting reciprocating the file . as is obvious , the casing is split into two halves to gain access to the connection between the file assembly and the dome of the reciprocal converting mechanism . it is typical in this type of these types of instruments to provide irrigation to the surgical site . to this end , the casing 12 includes port 42 and the lubricant transmittal tube 44 that is connected to the lumen 46 formed in the file assembly 20 . the next portion . of this application will describe the inventive cam / drum configuration of the motion converter 18 . the stub shaft 66 is suitably connected to the drive shaft 34 of motor 16 and carries pinion gear 68 at the distal end thereof ( the connection may equally be made by a direct connection without the use of a stub shaft ). pinion gear 68 , in turn , meshes with each of the planetary gears 70 , ( three in number ) which , in turn , meshes with the fixed ring gear 72 . ring gear 72 is fixed to the earn outer casing 73 via the dowel pin 75 disposed in the slot 77 formed in the flange 79 . ( the ring gear can be made integral with the earn outer casing ). as is apparent from fig3 , each of the planetary gears 70 are rotary supported to stub shaft 74 which is suitably pinned to platen 76 . platen 76 is a portion of the rotating cam 78 which is rotated by the spinning planetary gears 70 . cam 69 includes the main body 71 that has formed therein the cam slot 80 that is designed to produce reciprocal motion as will he apparent from the following description . follower 84 fitted into the cam slot 80 is pinned via pin 86 to drum 88 . as noted , and in accordance with this invention , a single cam follower is all that is necessary to drive drum 88 , drum 88 comprises the hollow sleeve 90 ( see fig4 ) having the aperture 92 formed on the peripheral side thereof the follower 44 consists of stub shaft 94 locks roller 96 to the hollow sleeve 90 via the recess 98 . a washer 100 may be used to assure that the roller has sufficient spacing so that its rolling around shaft 94 is not impaired . in accordance with this invention , two ( 2 ) thrust pins 102 and 104 fit into annular groove 106 formed in the cam . the thrust pins 102 and 104 are grounded to the earn casing 108 and serve to absorb the thrust loads so as to allow the efficient operation of the surgical file . in operation , the motor drives shaft 66 and pinion gear 68 which , in turn , meshes with the three ( 3 ) planetary gears 70 which , in turn , meshes with the fixed ring gear 72 . this re - action of all of the above mentioned gears rotates the cam 69 via the platen 76 . the platen 76 which is integral with the cam 69 , as a consequence , is rotated . this motion , in turn , is converted to reciprocal motion via the follower 44 that drives the drum in a reciprocal motion . obviously , this motion is translated to the surgical file by the connection described above . also , in accordance with this invention the surgical file is unique as will be described in detail herein below . as mentioned above the file assembly comprises a longitudinally extending outer tube 112 that has formed thereon at . the distal end a flat or planar shaped shield and guide member 114 . a longitudinally extending solid rod 114 is tightly fitted into tube 112 formed with the “ infinity shaped ” slot 116 and a pair of lumens 46 and 47 . ( see fig2 a ) and a generally longitudinally extending file 50 that fits into the infinity slot 116 and extends beyond the distal end of the solid rod 114 wherein the blade is complimentary dimensioned to the guide / shield and portions of the lower surface thereof are contiguous to portions of the upper surface of the guide / shield and in sliding relationship in the longitudinal direction . in its preferred embodiment , the elements in the surgical file assembly are bent 30 degrees adjacent to the proximal end and at the same angle adjacent to the distal end . obviously , the particular shape and dimensions of the elements in the surgical file assembly will be predicated on its particular use . as shown in fig6 - 8 , the cutting surface of the blade 50 consists of a plurality of radial projecting ring - like elements or micro holes 120 that serve as cutting edges 122 . as mentioned earlier , the particular file head is not a concern of this invention . however , of importance is the shape of the guide / shield 114 and its relationship to the file head . formed on shield 114 is the elongated dimple 124 extending longitudinally along the central portion of shield 114 . the dimple includes the apex 126 and the straight slopes 128 and 130 extending from the top portion along either sides there of . this particular configuration defines a rail that centers the file and keeps its motion in a linear straight line which obviously , is important for the delicate types of precision operations to which the surgical file instrument is used . the lower portion of the shield 114 to extends radial toward the outer edges of file blade 50 and is bent slightly upwardly to be in contiguous contact with the side edges of file blade 50 . as is apparent from the foregoing the guide / shield provides an efficient support for the file blade 50 while assuring that the tissue or body parts adjacent to the operation site are not bruised or injured . although this invention has been shown and described with respect to detailed embodiments thereof , it will be appreciated and understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and scope of the disclosed invention .
a surgical file instrument including a surgical file assembly having an elongated tubular member with a guide / shield supporting the blade of the surgical file and being formed on the distal end thereof , the guide / shield portion being generally planar shaped and having an elongated longitudinally extending dimple defining a rail for guiding said blade and keeping it central and preventing wobbling . the side edges of said guide / shield extend upwardly and bear against the underside of the blade for supporting the same .