Patent Publication Number: US-2022211392-A1

Title: Handle for modular tool

Description:
FIELD OF THE INVENTION 
     The present invention relates to modular tools, and in particular a handle element for such tools. 
     BACKGROUND OF THE INVENTION 
     The concept of modularity in tools is almost as old as tool use itself. Many ancient tool designs such as hammers, axes, picks and the like comprise a working element fixed to a handle by some means which allows the periodic replacement of one element or the other. Developments in manufacturing processes over the last two hundred years meanwhile have made it possible to develop releasable fixing mechanisms. For example, screw driver heads are commonly available as 6.35 mm (quarter inch) hexagon bits, which may be inserted as required in a standard handle. The bits may be secured magnetically, or by means of a spring loaded ball bearing engaging a groove in the bit. In some contexts meanwhile, the operational constraints extant in that context may tend to lead away from such approaches. In the field of surgical instruments for example, the high forces involved along with sterilisation requirements may tend to indicate an all-in-one approach. 
       FIG. 1  shows an orthopaedic reamer as known in the state of the art. 
     As shown in  FIG. 1 , a reamer  100  comprises a handle  102  with a strike head  101  and a reamer working surface  103 . The reamer  100  is typically made entirely of stainless steel. 
     Notwithstanding the foregoing, the cost of manufacturing a complete set of stand-alone tools for example as shown in  FIG. 1  can be considerable, and even in the field of surgical tools, some attempts at modular tools are known. 
     In this, as in any field where a solid positive engagement between the handle and further elements is a critical requirement, special consideration must be given to the securing mechanism. 
       FIG. 2  shows a releasable securing mechanism for modular tools as known in the state of the art. 
       FIG. 2  shows a conventional securing mechanism known in the art as a “Hudson Fitting”. In particular,  FIG. 2  shows a male Hudson fitting  200 , attached to a tool element  201 . The fitting comprises a cylindrical member  203  with a semi-circular channel or groove  204 . When the cylindrical member  203  is slid into the corresponding female element, a spring loaded ball bearing  205  engages the channel so as to prevent accidental decoupling. In implementations where uncoupling must be avoided in the presence of a separating force, the ball bearing may be replaced with a removable cotter pin or the like. As shown, the fitting also comprises a flattened flange  202  at the proximal end of the fitting closest to the tool element  201 . The flats of this flange may engage corresponding surfaces on the corresponding female element when the coupling is fully inserted, so that rotational forces may be effectively transferred between the two elements of the coupling. 
     Fittings such as that shown in  FIG. 1  have been found unsatisfactory in terms of their ability to provide a solid positive engagement between the handle and further elements, whilst supporting uncoupling with a minimum of force and dexterity when required, yet averting the risk of accidental uncoupling. As such, it is desired to provide an improved coupling addressing some or all of these concerns. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention in a first aspect there is provided a handle for a modular tool comprising a body having a distal end and a proximal end. The distal end provides a releasable coupling for an element of the modular tool, the releasable coupling comprising a cylindrical member provided with a first external helical thread, and a lateral slot. The slot opens on one periphery of the distal end of the body and widens from the distal end towards the proximal end of the handle. The releasable coupling further comprises a threaded ring, the threads of the ring engaging the first external helical thread of the cylindrical member, the threaded ring being rotatable about the distal end of the member between an extended position in which the ring obstructs the slot opening on one periphery of the distal end of the body, and a retracted position in which the ring leaves the slot opening on one periphery of the distal end of the body unobstructed. 
     In accordance with a development of the first aspect, the lateral slot defines a T slot or dovetail. 
     In accordance with a further development of the first aspect, the dimensions of the lateral slot vary radially so that the force required to slide a corresponding keyed element of the secondary element into the lateral slot increases as the corresponding keyed element of the tool progresses into the slot. 
     In accordance with a further development of the first aspect, the angular displacement of the threaded ring when rotated between the extended position and the retracted position is between 170 and 190 degrees. 
     In accordance with a further development of the first aspect, the threaded ring comprises an indentation at the distal edge thereof, the indentation being positioned on the circumference of the ring such that when the ring is in the retracted position the indentation is aligned with the slot. 
     In accordance with a further development of the first aspect, the cylindrical member is provided with a second external helical thread parallel the first external helical thread, and wherein the threads of the ring engage both the first external helical thread and the second external helical thread of the cylindrical member. 
     In accordance with a further development of the first aspect, the first helical thread has a first root to crest ratio, and the second helical thread has a second root to crest ratio, wherein the threads of the ring are defined so that the ring can only engage the corresponding respective helical thread, and thereby may only be mounted on the handle in one configuration. 
     In accordance with a further development of the first aspect, the pitch, the minor diameter, the major diameter, or the root to crest ratio of the of the first external helical thread varies along the length of the first external helical thread so that the force required to rotate the ring increases as the ring is rotated about the distal end of the member from the retracted position to the extended position. 
     In accordance with a further development of the first aspect, modular tool comprises a surgical instrument. 
     In accordance with a further development of the first aspect, modular tool is for surgery of the orthopaedic surgery or bone traumatology. 
     In accordance with a further development of the first aspect, modular tool comprises a rasp or reamer or impactor. 
     In accordance with a further development of the first aspect, the modular tool comprises the handle, an interface part being releasably coupled to the handle and a working part being releasably coupled to the interface part. 
     In accordance with a further development of the first aspect, the handle is composed of a synthetic material or a synthetic composite material. 
     In accordance with a further development of the first aspect, the handle is composed of a glass fibre reinforced polyarylamide. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other advantages of the present invention will now be described with reference to the accompanying drawings, for illustration purposes only, in which: 
         FIG. 1  shows an orthopaedic reamer as known in the state of the art; 
         FIG. 2  shows a releasable securing mechanism for modular tools as known in the state of the art; 
         FIG. 3  shows a handle for a modular tool in accordance with an embodiment; 
         FIG. 4 a    shows the handle in a first, retracted position prior to the insertion of the secondary element  305 ; 
         FIG. 4 b    shows the handle in a first, retracted position after insertion of the secondary element  305 ; 
         FIG. 4 c    shows the handle in a second, extended position after insertion of the secondary element  305 ; 
         FIG. 5 a    shows a sectional view of the slot in a first embodiment; 
         FIG. 5 b    shows a sectional view of the slot in a second embodiment; 
         FIG. 6  shows a plan view of a keyed element corresponding to the slot of  FIG. 5   a;    
         FIG. 7  shows a tool in accordance with an embodiment; 
         FIG. 8 a    shows further detail of the embodiment of  FIGS. 3 to 7 ; 
         FIG. 8 b    shows a variant of the arrangement of  FIG. 8   a.    
     
    
    
     DETAILED DESCRIPTION 
       FIG. 3  shows a handle for a modular tool in accordance with an embodiment. As shown, the handle  300  is provided with a body  310  having a distal end  301  and a proximal end  302 . The distal end  301  provides a releasable coupling for a secondary element  305  of the modular tool. The releasable coupling comprises a cylindrical member  311  provided with a first external helical thread  312 , and a lateral slot  313 , the slot opening on one periphery of the distal end  301  of the body  310 , the slot widening from the distal end  301  towards the proximal end  302 . The releasable coupling further comprises an internally threaded ring  320 , the threads of the ring  320  engaging the first external helical thread  312  of the cylindrical member  311 , the threaded ring  320  being rotatable about the distal end  301  of the cylindrical member  311 . 
     While the handle is shown substantially as a cylinder with its major axis extending from the distal to proximal end, the skilled person will appreciate that other forms may be provided depending on the intended use of the handle. In particular, the handle may alternatively be “T” shaped, with the cross bar of the “T” at the proximal end of the handle so that the user may grip the handle for example with the index and middle finger on one side of the vertical, and the ring and small finger on the other side. Similarly, the handle may alternatively be “D” shaped, with the vertical of the “D” at the proximal end of the handle so that the user may grip the handle at right angles (or some other angle as required) to the major axis of the handle. 
     Where a plurality of helical threads are provided, one or more of these threads may have dimensions different to other threads, such that the ring can only engage the cylindrical member in the desired orientation, for example so as to ensure proper positioning of the optional detent with respect to the slot in the extended and retracted positions. For example, the helical thread has a first root to crest ratio, and the second helical thread has a second root to crest ratio, wherein the threads of the ring are defined so that the ring can only engage the corresponding respective helical thread, and thereby may only be mounted on the handle in one configuration. 
     Similarly, the circumferential spacing of the threads may be varied to achieve the same effect. 
     The threads on the cylindrical member and/or the ring need not be continuous. 
     As shown, the ring is provided with an optional detent  321 , in the distal circumferential edge thereof. 
     It will be appreciated that there is provided a secondary element having features in correspondence to the handle of the present invention, and in particular to the releasable coupling thereof. In particular, there is provided a secondary element for a modular tool, the secondary element having a distal end and a proximal end disposed on a longitudinal axis, the distal end of said secondary element being enclosed within a notional cylinder  307 . The secondary element comprises a first keyed element  306  widening in a distal direction. A trailing edge  308  of the keyed element conforms to the cylinder  307 , whereby said secondary element may be secured in a corresponding handle by inserting said first keyed element  306  with the trailing edge  308  outward into a corresponding slot defined in said handle, whereby a ring  320  of said handle corresponding to said cylinder may be slid into position so as to block said keyed element  306  in said handle. 
     The trailing edge  308  of the keyed element which conforms to the cylinder may furthermore be partially threaded so as to provide a continuous thread with threads provided in a cylindrical member of the handle, and adapted to engage threads of the ring as described above. 
       FIGS. 4 a , 4 b  and 4 c    show the handle of  FIG. 3  in different configurations. 
     As shown, the threaded ring  320  is rotatable about the distal end  301  of the member  311  from a first, retracted position as shown in  FIGS. 4 a  and 4 b   , to a second, extended as shown in  FIG. 4   c.    
       FIG. 4 a    shows the handle in a first, retracted position prior to the insertion of the secondary element  305 . The secondary element may comprise a tool. For example, the tool may comprise a surgical instrument. More particularly for example, the tool may be for surgery of the orthopaedic surgery or bone traumatology. Still more particularly for example tool may comprise a rasp or reamer or impactor. Alternatively, the secondary element may comprise an intermediate adaptor between the handle and a further component, where the further component may comprise a tool as discussed above or otherwise. 
     As shown, the secondary element  305  comprises a tongue or keyed element  306  which has a form complementary to the slot  313 . As shown the ring  320  is in a retracted position in which the ring leaves the slot opening on one periphery of the distal end of the body unobstructed. By this means, the keyed element  306  of the secondary element  306  may be introduced into the slot  313  of the handle. 
     As shown, the optional detent  321  aligns with the slot in the retracted position. 
       FIG. 4 b    shows the handle in a first, retracted position after insertion of the secondary element  305 . 
     Since the slot  313  widens from the distal end  301  towards the proximal end  302 , a correspondingly formed keyed element  306  may be slid into the slot laterally as shown in  FIG. 4 b   , but once in position, will not be movable along the axis of the handle, i.e. towards or away from the distal end of the handle, but only back or forth along the axis of the slot. 
       FIG. 4 c    shows the handle in a second, extended position after insertion of the secondary element  305 . As shown in  FIG. 4 c   , the ring has been rotated about the cylindrical member  311 , so that through the engagement of the threads of the ring in the threads  312  of the cylindrical member, this rotational movement has been translated into a linear movement towards the distal end of the handle, so that the ring obstructs the slot opening on one periphery of the distal end of the body. 
     As shown, this movement comprises a rotation of 180° clockwise about the axis of the handle when viewed down the length from the proximal to the distal end of the handle. The skilled person will appreciate that the pitch of the threads and the angle through which the ring is rotated will determine the distance along the cylindrical member that the ring  320  travels. On one hand it is desirable that the distance travelled should be as great as possible, to allow the use of a long keyed element  306 , providing a strong and rigid connection between the handle and secondary element. On the other hand, in use it will be desirable that the user be required to turn the circle through as small an angle as possible, so that the manipulation may be performed with the lowest possible demand on the user&#39;s dexterity. The chosen compromise between these considerations is defined by the pitch of the respective threads of the ring and the cylindrical member. On this basis, the angular displacement of the ring between the extended position and the retracted position is preferably less than 361°, more preferably less than 271°, more preferably less than 181°. A multiple of 90° may be advantageous in terms of being more intuitive to the user. The angular displacement of the ring between the extended position and the retracted position is preferably more than 89°. The chosen compromise between these considerations is defined by the pitch of the respective threads of the ring and the cylindrical member. 
     Additional constraints may occur through a desire to limit the likelihood of the ring moving along the cylindrical member under its own weight, or in response to an accidental or incidental pressure, which will tend to favour a tighter pitch, although these considerations may also be managed by selecting materials, surfaces and/or tolerances so that the friction between elements reduces the risk of such unwanted movement. On this basis, the threads of the ring and cylindrical member may be configured in accordance with an embodiment such that the ring is turned through substantially one single revolution or less between the extended position and the retracted position. In accordance with a further embodiment the ring is turned through substantially one half revolution or less between the extended position and the retracted position. In accordance with a further embodiment the ring is turned through substantially one quarter revolution or less between the extended position and the retracted position. In accordance with a further embodiment the ring is turned through substantially one third revolution or more between the extended position and the retracted position. Meanwhile, the threads of the ring and cylindrical member may be configured in accordance with an embodiment such that the ring moves along the axis of the cylindrical member a distance substantially equal to 2 cm or less between the extended position and the retracted position. In accordance with a further embodiment the ring moves along the axis of the cylindrical member a distance substantially equal to 1.5 cm or less between the extended position and the retracted position. In accordance with a further embodiment the ring moves along the axis of the cylindrical member a distance substantially equal to 1 cm or less between the extended position and the retracted position. The skilled person will appreciate that any combination of angle of rotation and linear displacement may be selected within these ranges, and indeed outside these ranges. It may be noted that the thread of the cylindrical member and ring of  FIGS. 4 a , 4 b  and 4 c    comprises a double thread. A double thread may be advantageous in providing a firm engagement between the threads of the ring and the cylinder while permitting a short threaded section along the length of the ring, so as to minimise the dimensions of the ring. The skilled person will appreciate that a single thread may also be adequate in many implementations. The skilled person will appreciate that a three or even more threads may be appropriate in other implementations. 
     As shown in  FIGS. 3 and 4   a , the slot  313  defines substantially a T cross section, and the keyed element  306  is shaped correspondingly. This shape achieves the objective of ensuring that the keyed element can only enter or exit the slot through the lateral opening of the cylindrical section, and that once the ring is in the extended position, no force in any direction on the secondary element with respect to the handle will separate the secondary element from the handle. The skilled person will recognise that the keyed element and corresponding slot may have any form complying with the general requirement that it widens from the distal end towards the proximal end. As such, it may form a wedge, dovetail or T section as described above. It may furthermore be circular, elliptical, rectangular, square, or any other form. The keyed element will generally constitute an extrusion of the chosen cross section from one side to the other. In certain embodiments, the keyed element may taper from one side to the other. Where this is the case the slot may taper from side to side correspondingly. Where this is the case, the slot may be defined as being deeper from side to side that the length from side to side of the corresponding keyed element. On this basis, the tapering walls of the keyed element will engage the sides of the keyed element before the end of the keyed element reached the lateral extremity of the slot. By this means, the slot will become progressively tighter as the keyed element is inserted, and a firm insertion without any play between the handle and secondary element may be achieved by pushing the keyed element fully into the slot. 
       FIG. 4 c    shows the handle in a second, extended position after insertion of the secondary element  305 . 
     As shown, the ring  320  has been rotated through 180° clockwise about the cylindrical member  311 , and by the action of the engagement between the threads  312  on the cylindrical member  311  with those of the ring, the ring has progressed along the length of the cylindrical member so as to block the slot  313 . It may further be noted that while in the retracted position as shown in  FIGS. 4 a  and 4 b    the optional detent  321  aligns with the slot, in the extended position of  FIG. 4 c    the optional detent  321  no longer aligns with the slot. As such, the provision of the slot  321  means that the slot can be effectively blocked by a smaller linear movement of the ring. 
     As such, as shown the keyed element of the secondary element  305  is entirely trapped in the slot by the new position of the ring, as the result of a simple half turn (in the present example) of the ring, which may be effectuated by the user with a movement of the thumb, retaining the tool in the other fingers of the actuating hand, and leaving the other hand free. To further facilitate this action, the ring may be knurled, grooved, provided with a non-slip coating, provided with flats or otherwise treated to improve the users grip thereon. Where the ring is provided with flats, these may be even in number, and may further be dimensioned so that they may be engaged using a spanner of standard dimensions, for example as defined in ISO/TC  29 /SC  10  and the like. 
     In certain embodiments, the shape or dimension of ring and cylindrical member, and in particular the thread on either or both of the ring or the cylindrical member may vary along their length, for example such that their engagement becomes progressively tighter towards the extended position, so that while it may move freely at certain portions of its travel, as it approaches the extended position it becomes somewhat resistant to movement. This approach may be advantageous in further reducing the risk of the ring being moved from the extended position inadvertently, which might otherwise lead to a loosening or even decoupling of the secondary element from the handle. Similarly, the engagement between the ring and cylindrical member may become progressively tighter towards the retracted position, so that while it may move freely at certain portions of its travel, as it approaches the retracted position it becomes somewhat resistant to movement. This approach may be advantageous in further reducing the risk of the ring being moved from the retracted position inadvertently, which might otherwise complicate the task of inserting the keyed element of the secondary element. The variations in shape or dimensions may include for example variations in the pitch, the minor diameter, the major diameter, or the root to crest ratio or any combination of these. Additionally or alternatively a similar effect may be achieved by a variation in the outer diameter of the cylindrical member and/or the inner diameter of the ring along the length thereof, for example so that as the ring moves towards the extended position, it becomes progressively tighter on the cylindrical member and/or so that as the ring moves towards the retracted position, it becomes progressively tighter on the cylindrical member. 
     As discussed above, the slot (and correspondingly the keyed element) widens from the distal end towards the proximal end. As discussed above, the slot, and correspondingly the keyed element may take many forms whilst satisfying this requirement.  FIGS. 5 a  and 5 b    show two possible such implementations. 
       FIG. 5 a    shows a sectional view of the slot in a first embodiment. 
     As shown in  FIG. 5 a   , the slot  313   a  is generally T shaped in cross section. It may be noted that the shoulders defining the top of the narrow stem of the T shape are not entirely parallel with the flat top of the T shape. In other embodiments, these shoulders may be parallel with the top, or adopt any other angle as may be found to be expedient. 
       FIG. 5 b    shows a sectional view of the slot in a second embodiment. 
     As shown in  FIG. 5 b   , the slot  313   b  is generally in the form of a dovetail in cross section. 
     As shown in both  FIGS. 5 a  and 5 b   , the dimensions of the lateral slot vary radially (that is, from the edge towards the middle) so that the force required to slide a corresponding keyed element of the tool into the lateral slot increases as the corresponding keyed element of the tool progresses into the slot. 
       FIG. 6  shows a plan view of a keyed element corresponding to the slot of  FIG. 5   a.    
     The keyed element of  FIG. 6  corresponds to that of the secondary element  305  shown in  FIG. 3 . As shown, the slight tapering of the keyed element is visible. 
       FIG. 7  shows a tool in accordance with an embodiment. 
     As shown, there is provided a modular tool  700  comprising a handle  710  substantially as described above, and a secondary element  705  substantially as described above. The handle  710  comprises a releasable coupling substantially as described above, and in particular comprising a threaded ring  720 , the threads of the ring engaging an external helical thread of the cylindrical member of the handle  700 . The threaded ring  720  is rotatable about the distal end of the member between an extended position as shown in which the ring obstructs a slot opening on one periphery of the distal end of the body, and a retracted position in which the ring leaves the slot opening on one periphery of the distal end of the body unobstructed. 
     The handle may optionally be provided with an angle datum such as a radial line on the guard plate, or a radial lumen through which a bar may by inserted. 
     As shown, the handle further comprises an optional guard plate  702  at the proximal end thereof. Such a guard plate may serve to protect the hand of a user when gripping the handle  710  from blows struck against the proximal end thereof with a hammer, mallet or the like, for example where the tool  705  is a chisel, reamer or other such tool requiring a percussive application. 
     One field in which a handle as described may be appropriate is that of surgical instruments, such that the modular tool as a whole may comprise or constitutes a surgical instrument. More particularly, the modular tool may be for orthopaedic surgery or bone traumatology. More particularly, the modular tool may be is for surgery of the hip, shoulder or knee. More particularly, as shown, a working part  706 , and thus the modular tool as a whole  700  comprises a rasp or reamer or impactor. It will be appreciated that in line with the many fields of application and associated tool types that may be envisaged, many different possible working parts  706  may be envisaged, for use with a single handle in accordance with embodiments as described above. Further examples of possible working parts, and resulting modular tools, include head impactor  706   b  (adapted to exert a force on an implant head  790 ), implant impactor  706   c , which are examples of working parts that may be attached directly to the handle without a separate intervening secondary element  705 , a curved rasp  706   e , osteotome  706   d  which are further examples of working parts that may be attached directly to the handle by means of a separate intervening secondary element  705  and many other tools as will readily occur to the skilled person. 
     While the working part may incorporate the keyed part as described above, there may alternatively be provided a separate interface part as described above being releasably coupled to the handle as described above, and a working part being releasably coupled to the interface part, by a further releasable coupling means, which may comprise an additional ring mechanism as described above, a Hudson fitting as known in the state of the art, or any other convenient mechanism. 
     The handle of the present invention may be formed of any material. In particular, it may be formed of steel, aluminium, titanium or any other suitable metal or alloy. It may also be formed of a thermoplastic or other synthetic material. It may in particular be formed from a polyamide, for example a polyarylamide. The synthetic material may comprise additional components such as a filler, swelling agent and the like. It may still further be formed of a synthetic composite material, comprising a glass, carbon fibre, carbon nanoparticle or any other material exhibiting a high tensile strength, in a matrix of a synthetic material, such as any of those listed above. In certain embodiments, the handle of claim  13  wherein the handle is composed of a glass fibre reinforced polyacrylamide, such as for example that marketed by the Solvay corporation under the trademark “Ixef 1022” or more particularly “Ixef GS 1022”. 
     The handle may be formed of different materials in different regions, including metal parts and synthetic parts. The handle may also comprise voids for the purpose of economy of material, reduced weight and so on. 
       FIG. 8 a    shows further detail of the embodiment of  FIGS. 3 to 7 . 
     In particular,  FIG. 8 a    shows elements  305 ,  306 ,  310 ,  313  and  320  as described above with reference to  FIG. 3 . Meanwhile, as shown a line  801  represents the axis along which a secondary element  305  as described herein may be slid into the coupling element  313 . Meanwhile, element  802   a  defines a plane aligned with the working plane in with which the longitudinal axis of the handle secondary element, and/or tool element mounted therein is aligned. As shown in  FIG. 8 a   , the plane  802   a  is also aligned with the line  801 . 
       FIG. 8 b    shows a variant of the arrangement of  FIG. 8   a.    
     In particular,  FIG. 8 b    shows elements  305 ,  306 ,  310 ,  313  and  320  as described above with reference to  FIG. 3 . Meanwhile, as shown a line  801  represents the axis along which a secondary element  305  as described herein may be slid into the coupling element  313 . Meanwhile, element  802   a  defines a plane aligned with the working plane in with which the longitudinal axis of the handle secondary element, and/or tool element mounted therein is aligned. As shown in  FIG. 8 b   , the plane  802   a  is at an angle α, designated by element  803 , with respect to the line  801 , as rotated about the axis of the handle, so that the secondary element  305  as described herein may be seen as being slid sideways in into into the coupling element  313  of the handle. 
     This approach has the advantage with respect to that of  FIG. 8 a    that forces exerter in the working plane  802   b  will not tend to disassociate the secondary element from the handle as may be the case with the configuration of  FIG. 8   a.    
     As shown in  FIG. 8 b    the angle α the angle is 90°, so that the secondary element is typically inserted from the user&#39;s right. This may be convenient for a left handed user holding the handle in their left hand, and using their right hand to insert the tool holder. The skilled person may select an angle α as may be convenient. For example the angle α the angle may be selected as 270°, so that the secondary element is typically inserted from the user&#39;s left. This may be convenient for a right handed user holding the handle in their left hand, and using their right hand to insert the tool holder. 
     Angles smaller than 90° or greater than as 270° may mean that while forces in the working plane have a component in the insertion axis  801 , this will tend to push the secondary element further into the coupling. 
     Angles between 90° and 270° may mean that a user can conveniently insert the secondary element by bringing the secondary element towards themselves, which may be easier in a constrained space. 
     The skilled person will recognise that intermediate angles may be selected as appropriate in view of the particular intended use conditions, which may combines these and other benefits in desired proportions. 
     Accordingly, there is provided a handle for a modular tool as described above wherein the modular tool has a working plane, and wherein the axis of said lateral slot is at an angle with respect to said working plane. 
     It will be understood that the configurations and/or approaches described herein are exemplary in nature, and that these specific embodiments or examples are not to be considered in a limiting sense, because numerous variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. As such, various acts illustrated and/or described may be performed in the sequence illustrated and/or described, in other sequences, in parallel, or omitted. Likewise, the order of the above-described processes may be changed. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various processes, systems and configurations, and other features, functions, acts, and/or properties disclosed herein, as well as any and all equivalents thereof. 
     Accordingly there is provided a handle for a modular tool in which the handle may be releasably coupled to a working part such as a rasp, reamer or impactor, or to a secondary element which may itself be connected to a working part. The coupling comprises a cylindrical member provided with one or more external helical thread, and a lateral slot opening on one periphery of the handle. A threaded ring has threads engaging the threads of the cylindrical member, and is rotatable about the cylindrical member between an extended position in which the ring obstructs the slot opening, and a retracted position in which the ring leaves the slot opening unobstructed. Accordingly, when the ring is in the retracted position a keyed element of the working part or secondary element may be slide from the side into the slot of the handle, and then once the ring is rotated to the extended position, the working part or secondary element is locked in place. 
     It will be understood that the configurations and/or approaches described herein are exemplary in nature, and that these specific embodiments or examples are not to be considered in a limiting sense, because numerous variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. As such, various acts illustrated and/or described may be performed in the sequence illustrated and/or described, in other sequences, in parallel, or omitted. Likewise, the order of the above-described processes may be changed. 
     The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various processes, systems and configurations, and other features, functions, acts, and/or properties disclosed herein, as well as any and all equivalents thereof.