Abstract:
The present invention relates to medical and veterinarian rotary tools. In particular, the present invention relates to a rotary tool for the taking of biopsies and drilling into tissues such as nail and bone. More particularly, the present invention relates to nail care devices and procedures to improve the condition of nails, especially relating to the treatment of fungal infections. Onychomycosis is a fungal infection that causes the toenails and/or fingernails to thicken, discolour, and split. Onychomycosis can result in permanent nail deformity. The disease can have a significant impact on a patient&#39;s quality of life arising from psychosocial issues e.g., due to concern regarding the appearance of one&#39;s toenails and fingernails, and may cause pain associated with wearing shoes. The present invention seeks to provide an improved mechanical system for use in the treatment of onychomycosis and other nail bed conditions, and other animal keratin, bone and cartilaginous conditions.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to medical and veterinarian rotary tools. In particular, the present invention relates to a rotary tool for the taking of biopsies and drilling into animal tissues such as nail, claw, hoof, bone and cartilaginous matter. More particularly, the present invention relates to nail care devices and procedures to improve the condition of nails, especially relating to the treatment of fungal infections. 
       BACKGROUND TO THE INVENTION 
       [0002]    Onychomycosis is a fungal infection that causes the toenails and/or fingernails to thicken, discolour, and split. The prevalence of onychomycosis in the United States population as a whole is 13%, onychomycosis being more prevalent in the elderly (60%). Onychomycosis can result in permanent nail deformity. The disease can have a significant impact on a patient&#39;s quality of life arising from psychosocial issues e.g., due to concern regarding the appearance of one&#39;s toenails and fingernails, limiting a choice of sandals or shoes, on the one hand and pain associated with wearing shoes, walking and sports activities on the other hand. There may be occurrences of a foul odour. 
         [0003]    Common causes of onychomycosis include dermatophytes,  Candida,  and nondermatophytic moulds. Dermatophytes are the fungi most commonly responsible for onychomycosis in the temperate western countries; while  Candida  and nondermatophyte moulds are more frequently involved in the tropics and subtropics with a hot and humid climate. Onychomycosis is more likely in the elderly due to diminished blood circulation, longer exposure to fungi, and nails which grow more slowly and thicken, increasing susceptibility to infection. Nail fungus tends to affect men more often than women, and is associated with a family history of this infection. Other risk factors include perspiring heavily, being in a humid or moist environment, psoriasis, wearing socks and shoes that hinder ventilation and do not absorb perspiration, going barefoot in damp public places such as swimming pools, gyms and shower rooms, having athlete&#39;s foot (tinea pedis), minor skin or nail injury, damaged nail or other infection, and having diabetes, circulation problems—which typically also lead to lower peripheral temperatures on hands and feet—or a weakened immune system. 
         [0004]    In view of the above, it is important that diagnosis is correctly performed. To avoid misdiagnosis as nail psoriasis, lichen planus, contact dermatitis, nail bed tumours (melanoma), trauma, or yellow nail syndrome, laboratory confirmation may be necessary. The three main approaches are potassium hydroxide smear, culture and histology. This involves microscopic examination and culture of nail scrapings or clippings. Recent results indicate the most sensitive diagnostic approaches are direct smear combined with histological examination, and nail plate biopsy using periodic acid-Schiff stain. To reliably identify nondermatophyte moulds, several samples may be necessary. Clippings may have been treated with an anti-fungal agent and so may not provide an accurate diagnosis. Other nail conditions include subungual haematoma, usually caused by a crush injury, which causes symptoms such as intense pain and throbbing as blood collects under the nail. The nail develops a black discoloration overlying the nail bed but under the nail plate. 
         [0005]    Treatment of onychomycosis is challenging because the infection is embedded within the nail and is difficult to reach. It may take a year or more of treatment, since new nail growth must entirely replace old, infected growth. Most treatments are either topical or oral antifungal medications. Oral medications include: terbinafine (76% effective), itraconazole (60% effective) and fluconazole (48% effective). Oral terbinafine is better tolerated than itraconazole. The use of an oral antifungal therapy in persons without a confirmed infection is a particular concern because of the side effects of that treatment. For superficial white onychomycosis, systemic rather than topical antifungal therapy is advised. Topical agents include: ciclopirox nail paint, clotrimazole, amorolfine or butenafine. Topical treatments need to be applied daily for prolonged periods (at least one year). Topical ciclopirox results in a cure in 6 to 9% of cases and it is believed that amorolfine might be more effective, although ciclopirox, when used with terbinafine, appears to be better than each agent alone. 
         [0006]    A nail is homologous to a claw, which is a curved, pointed appendage, found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Nails and claws are made of hard protein called keratin. Claws are used to catch and hold prey in carnivorous mammals such as cats and dogs, but may also be used for such purposes as digging, climbing trees, self-defence, and grooming, in those and other species. In tetrapods, claws are made of keratin and consist of two layers. All Carnivora have claws, which vary considerably in length and shape. A nail that is big enough to bear weight is called a “hoof”. Infections such as fungal growth issues affecting humans can also affect pets, farm animals etc. 
         [0007]    Accordingly, treatment will typically involve nail removal by abrasive means and/or by drilling means. U.S. Pat. No. 4,990,134 (Auth) describes an abrasive tipped rotating cutting tool for use in removing abnormal deposits within a patient&#39;s vascular channels. The tip is covered with a material such as diamond grit, and is described as being rotated at high speed to pulverize any abnormal deposits contained within the vessel. The tip can be ellipsoidal in shape, and the coarseness of the abrasive material on the tip is variable from a particularly coarse grade, adjacent a distal end of the tip, to fine grade, adjacent a portion of the tip which has the widest diameter. The tool is described as using either an atraumatic tip or a preformable guide wire to guide the cutting tip through a patient&#39;s vessel. 
         [0008]    U.S. Pat. No. 4,180,058 (Brem) describes a method for treating pathological conditions of the nail, particularly onychomycosis. The method comprises the breaching of the protective keratin of the nail to form an opening therein, placing a caustic-keratolytic agent in the opening to enlarge it, and treating the nail through the opening with topical therapeutic agents for the pathological condition being treated, for instance, an antifungal agent for onychomycosis. In addition, thick calluses and painful plantar warts are described as being removed with modifications of this method. 
         [0009]    U.S. Pat. No. 6,572,580 (Feldman) describes a kit including a patch laden with topical anti-fungal medication and a set depth nail notcher for cutting a notch of predetermined depth in a nail plate, comprising a handle having a smooth flat surface, a longitudinal cutting edge protruding from the smooth flat surface to a height equal to the predetermined depth of the notch. A method is described for treating nail fungus, especially toenail fungus, comprising cutting a notch to a predetermined depth in a nail of a toe or finger infected with fungus and applying a topical anti-fungal medication to the toe or finger from a patch through the notch. 
         [0010]    WO2006104600 (Jamison) describes a nail drill configured to create a hole in a nail, such as a fingernail or toenail. The nail drill has a shaft extending from a handle. A tip is disposed on an end of the shaft not coupled to the handle and has one or more cutting sections configured to cut into a nail. The nail drill is described as being utilized for relieving a pressurized area underneath a nail, such as bodily fluid that may have collected due to a prior trauma or other condition. The method for relieving the pressurized area includes positioning the tip onto an outer surface of the nail. The shaft may be rotated so that the tip turns and cuts a hole in the nail. The shaft is rotated until a hole is created through the nail, enabling the bodily fluid to pass from the pressurized area through the hole, thereby relieving the painful condition. 
         [0011]    WO2013098555 (Thomas) provides a device including a hand held reusable electromechanical system and a single use cutting component as part of a treatment system for onychomycosis. The electromechanical system incorporates an electric motor and drive train to advance the cutting component through a nail, which also incorporates sensors for measuring the cutting resistance for the purpose of preventing the cutting device from overrunning into an associated nail bed below the nail. This document advises that once a suitable cutter has perforated a nail to produce an access port, a suitable anti-fungal agent can be applied to the nail bed through the access port. A helical cutter can be used to extract swarf, as is known and this document teaches that in a reverse mode of operation an antifungal agent may be applied, although scant detail is provided. US2014094808 (Herndon) teaches of a device comprising a bench-top drilling jig/assembly, a control module, mechanically connected to the drilling jig/assembly for controlling the depth of drilling by a drilling-motor and drill-bit; and a sensor, electrically connected to the drilling-motor and drill-bit and control module for detecting a change in an electrical impedance of a material being drilled. The drilling-motor and drill-bit is attached to a housing of the drilling assembly and is provided with an electrically insulated nosepiece made from e.g. Teflon having three or four feet to rigidly locate an entire drill assembly with respect to an outer surface of a material to be drilled. The system is requires hydration of nail material to be drilled, with the subject nail being soaked for two minutes in de-ionized water prior to commencement of drilling. A drill bit retaining chuck, is preferably of an electrically conductive material allowing for electrical impedance sensing through the drill motor to the drill bit in contact with the material to be drilled. US20140222003 (Herndon) relates to a precision bone drill and benefits from an electrically conducting nose piece comprising two tangs which engage into bone or nail substrate. 
       OBJECT TO THE INVENTION 
       [0012]    The present invention seeks to provide an improved mechanical system for use in the treatment of onychomycosis and other nail bed conditions. The present invention also seeks to provide easily replaceable components for the system. 
       STATEMENT OF INVENTION 
       [0013]    In accordance with a first aspect of the present invention, there is provided a rotary tool that is operable to drill into hard animal tissue substrate, the tool comprising a body, a chuck, a drill bit and a shroud, wherein; the body provides a mounting for the chuck to enable rotation of the chuck about an axis of rotation, the chuck being operably associated with a rotary input drive; the drill bit is an elongate member having a cylindrical shank at a first, proximal end, a cutting edge at a distal end; the chuck includes a circularly cylindrical aperture coaxial with said axis of rotation and is operable to accept a shank of the drill bit, there being a resilient member operable to assist coupling of the drill bit and the chuck, the shroud having a proximal coupling portion which engages with the body of the tool and a distal end which engages with the substrate the shroud defines an annular aperture tip about the axis of rotation, the aperture of the shroud having a diameter sufficient to allow axial movement of the distal end of the drill therethrough, the tip being operable to engage with the hard substrate; and, wherein the body is operable to permit axial movement of the chuck and drill bit relative to the shroud such that the drill bit can extend through the tip of the shroud, the shroud tip being operable to engage with a surface of the substrate. The present invention thus provides a hand-held device that can be employed with respect to a hard animal tissue substrate; the tip engaging with the substrate by way of friction or by way of physically engaging with a sharp edge or edges, whereby manual control can be effectively be performed without fear of slippage or damage arising from unwanted twisting and/or displacement arising from torque reaction upon start-up of the motor. 
         [0014]    The shroud may comprise a foot arrangement having a non-invasive gripping surface, being provided with a rubber/polymeric plastics foot. In the alternative, the annular tip has a sharp or pointed edge, which engages with the substrate by cutting into the external surface of the substrate. The shroud tip can define a first section comprising a material operable to engage a surface of the substrate by friction and a second section operable to engage the surface by penetration, by way of a line contact, a point contact or a serrated contact. There can be four or more areas of differing surface engagement type. Applicants have determined that by engaging with the substrate and applying forces axially with respect to the drill bit, then the initial contact torque reaction can be resisted and by reason of the forces reacting to a foot or tip in direct contact with the substrate, then the difficulties encountered by prior art device which do not engage or otherwise contact with the substrate allow imprecise holes to be made, with a risk of damaging soft animal tissue. By arranging a control switch co-axially with respect to the drill-bit, it has been found that in the application of forces used to control the operation can assist in the drilling operation generally. 
         [0015]    The shroud advantageously provides a passage for collection of swarf arising from drilling through the substrate. The present invention can thus provide a simple and easy to use device for producing holes in keratin for collecting biopsy material, drug delivery, relieving conditions such as subungal haematoma and the like. A specific advantage is that if a clinician decides to collect a biopsy for testing, then taking one from the nail root and below the nail plate (where the fungus resides) can be performed safely, simply and with minimal pain with the present invention. By having a shroud about the drill-bit, toward the shank, which opens out to an interior volume about the shank, then it has been found that swarf can be collected, for biopsy use later. 
         [0016]    Conveniently, the drill bit comprises a composite member comprising a first elongate member having a primary shank at a first end of the elongate member and a cutting bit at an opposite end of the elongate member, wherein a secondary shank member is provided having a circular cylindrical symmetry about an axis and an elongate aperture coaxial within said axis, into which the primary shank can be inserted and fastened thereto, whereby to provide a composite drill bit with a shank diameter greater than a cutting diameter. By the provision of a larger diameter shank than would otherwise be the case, the drill bit is more easily handled; small drill bits are particularly brittle and can easily be broken by poor handling. The drill bits can be simply manufactured from HSS materials as is known and preferred in many situations; carbide drill bits and other types of drill can also be used to reduce cost and enable competitive pricing of disposable units. Packaging of such disposable units may contain features to make ejection and disposal of single use cutters simple and safe to perform and facilitate any subsequent processing by laboratories in the case of biopsy examinations. 
         [0017]    The resilient member associated with the chuck and drill bit arrangement is a tight fit about or within one of the chuck and the drill bit and is operable to grip the other of the chuck and drill bit. Conveniently, the resilient member comprises a collet, associated with the shank of the drill bit, the collet having a resilient member which engages with the chuck. The collet can be manufactured from a machineable and mouldable plastics such as polypropylene. In one preferred embodiment, the resilient member comprises a collet arranged about a shank of the drill bit and has extending resilient fingers which operably clip into a surface feature of the chuck, to assist in at least one of retention of the drill bit and indication of securement of the drill bit. The resilient member can perform a first function to prevent the drill bit from sliding out of the chuck and a second function to prevent relative rotation thereof when in situ; this can be performed by elastic grip. In an alternative, mutually engagable portions can prevent relative rotation between the chuck and the shank of the drill bit. 
         [0018]    Conveniently, the tool is arranged such that rotation of the chuck and drill bit is only possible after engagement of the tip of the shroud with a substrate, whereupon the drill bit is permitted to move outwardly of the tip, such that, the drill bit can engage with and drill into the substrate. Conveniently, the motor or power source is torque sensitive whereby to prevent unwanted soft tissue damage. Conveniently, power is supplied upon engagement of the shroud engaging a work-piece such that a pressure switch is activated. Conveniently, the rotation of the drill bit can rotate in first and second directions of rotation abut said axis. This can be beneficial not only in the collection of biopsy material, but can also assist in the delivery of medicament. 
         [0019]    The shroud is provided with an apex that comprises an annular aperture tip with a substrate engagement portion; this aperture tip can comprise one of a sharp edge, a rough surface or an undulating surface. It is preferred that the shroud has have a sharp tip (relative to the keratin) and can be made from metals that will not easily corrode and are suited to sterilisation such as stainless steel or aluminium that has been anodised to increase hardness. The annular aperture tip can include a pressure-sensitive sensor, whereby to enable rotation upon engagement of the annular aperture tip with a surface. The shroud can be fabricated, for example, in part, close to the tip or generally, from a transparent or translucent material, whereby illumination from a light source within the shroud is possible or generally, to assist in viewing of the nail to be drilled. In the alternative, the tip, when provided with a foot having a non-slip polymeric plastics/rubber grip element can be provided in a number of styles. The foot may surround the annular opening for only 180° or 120°, for example, whereby to enable the tip to be placed close to the cuticle or eponychium of a fingernail/toenail. In a still further embodiment, the tip may define a plane that is not perpendicular to the axis f the drill bit, whereby the drill can enter a nail at an angle so as to enable a treatment, for example, to be applied under the cuticle or eponychium. Conveniently, the single use assembly prevents cross-infection and is sterilised during manufacture. 
         [0020]    It will be appreciated that a diameter of the drill bit and a diameter of the annular aperture tip are selected such that, when extended through the aperture of the shroud, the drill bit is close fitting with respect to the aperture of the shroud, whereby to provide support and enable passage of swarf from a substrate and/or passage of a fluid to clean and/or passage of a medicament to the substrate. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0021]    For a better understanding of the present invention, reference will now be made, by way of example only, to the Figures as shown in the accompanying drawing sheets, wherein: 
           [0022]      FIG. 1  illustrate a known drilling system comprising a power tool, drill bit and depth gauge; 
           [0023]      FIG. 2  shows the tool of  FIG. 1  being operated by way of an articulated handling tool; 
           [0024]      FIG. 3  shows a second known drilling system with an electronic depth control system; 
           [0025]      FIG. 4  shows a first embodiment in accordance with the present invention in sectional view; 
           [0026]      FIGS. 4 a -4 k    show specific details associated with the first embodiment; 
           [0027]      FIG. 5  shows an example of the present invention in operation; 
           [0028]      FIGS. 6 a -6 k    show examples of the tip of a shroud in accordance with the present invention in sectional and perspective views; 
           [0029]      FIG. 7  shows a further view of a shroud tip in section; 
           [0030]      FIG. 8  shows another shroud in accordance with the invention; 
           [0031]      FIGS. 9 a -9 e    show how a jig can be utilised in accordance with another aspect of the invention; 
           [0032]      FIG. 10  shows how a vacuum fan can be arranged; and, 
           [0033]      FIGS. 11 a  and 11 b    show how debris can be collected. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0034]    There will now be described, by way of example only, the best mode contemplated by the inventor for carrying out the present invention. In the following description, numerous specific details are set out in order to provide a complete understanding to the present invention. It will be apparent to those skilled in the art, that the present invention may be put into practice with variations of the specific. 
         [0035]    Referring to  FIG. 3 , the present invention relates to a device that is operable to drill a hole through a nail  301  using a drill bit  302  in a controlled manner which device is arranged to prevent an overrun of the drill bit in use, having progressed through the nail, into the nail bed  304  lying below. This prior art device benefits from motor control but suffers from being hand-held: the device must be held in against the nail  300  whereby to determine differences in torque resistance to the drill bit as it rotates. In this known system a drill bit is fixedly attached to a drill bit holder (chuck) in a controlled manner in order to accurately track the progress of the drill bit  302  through the nail  300  thus preventing it overrunning into the nail bed. When the device is first placed against the nail  300  the cutter  302  will not be in contact with the nail  300  (see  FIG. 5 ). Upon activation the cutter will start to rotate and will then be advanced in an axial direction towards the nail  300 . When the cutter  302  makes contact with the nail  300  there will be a reaction force from the nail  300  in a direction corresponding to the axis of the cutter  302  and a reaction torque will act with respect to the cutter  302 . This prior teaching provides a motor control responsive to such forces. 
         [0036]    Notwithstanding the above, difficulties can arise, not least through the axis of cutting changing through relative movement between the drill bit and the nail  300 . Accordingly, the present invention provides a number of modifications to the design to overcome or ameliorate such problems. Referring now to  FIG. 4 , numeral  400  refers generally to a drilling assembly in accordance with one aspect of the invention. The drilling assembly can be coupled to a motor for rotational drive or may be coupled to an output coupling of a flexible shaft, wherein the motor provides rotational drive at an input coupling of the flexible shaft. The assembly comprises a composite drill  403  retained for rotation within a chuck which is surrounded by a shroud  402 , which depends form an upper sleeve member associated with the motor drive unit (not shown), the composite drill being movable relative to the shroud. The shroud, by means of an annular sleeve  407  at a proximal portion of the shroud, engages with a corresponding mating face associated with the body  405  of the rotational tool. The composite drill  403  comprises a drill bit  302  and a shank element  304  (which receives rotational drive about axis Z from a rotational power from coupling member  411 ), associated with a control tool or device (not shown). For ease in handling and to assist in the coupling of the shank to the chuck, the outside diameter of the shank (typically, φ=3.175 mm, corresponding to ⅛th inch, a standard diameter for many engineering applications) is considerably greater than the drill bit (typically, φ=0.1−2 mm), although this would not be necessary for larger drill bits. At a distal portion of the shroud  406 , the shroud reduces in diameter to define an apex with an aperture through which the drill bit can pass and engage with a patient body part. For example, as shown in  FIG. 5 , the apex abuts a nail plate  300  prior to the drill bit being brought towards and through the aperture  406  at the base of the shroud. The chuck coupling member  411  has an inside diameter of 3.175 mm, corresponding to the outside diameter of the shank and an outside diameter of 5.5 mm. Whilst a resilient clip is shown in the specific embodiment, the skilled man will realise that a magnetic assembly can retain ferromagnetic drill bits, as such magnetic connections are widely used many in non-percussive applications, such as multi-bit magnetic screw-driver assemblies. 
         [0037]    In detail, and referring also to  FIGS. 4   a - c,  the shank  304  is retained within a power transfer chuck  411  that enables an extremely simple change of drill bit. With specific reference to  FIG. 4 a   , which shows a plan view of the composite drill  403  from the proximal end, although the drill bit cutter  302  is indicated in outline. The shank of the composite bit is provided with a plastics collet  408 , which has four upstanding elements  409  with inherent resiliency, being manufactured from machinable and mouldable plastics such as polypropylene. Four inwardly extending features  410  are defined at the end of the upstanding elements  409 . These inwardly extending features locate within an annular depression  412  associated with the transfer chuck  411 , whereby not only to assist in the confirmation of the drill bit being fitted satisfactorily but to assist in gripping an outside surface of the power transfer chuck  411 . An insertion tool operable to protect a brittle drill bit and reduce a risk of contamination can be provided, comprising an elongate tool with an inwardly direct opening operable to couple about the shank in a loose fit, an abut against the collet, whereby the drill bit is not touched and therefore not contaminated as the drill bit is placed within the transfer chuck  411 . 
         [0038]    The shank is machined to an outside diameter of 3.175 mm and the inside diameter of the chuck corresponds to provide a sliding fit, to prevent axial jitter of the drill in use; an air passage (not shown) is provided whereby to enable the shank to be simply inserted into the chuck. The tightness of fit is controlled by an amount of interference; the “allowance”. Formulas are readily available to the skilled man t to compute this allowance (planned difference from nominal size) that will result in various strengths of fit such as loose fit, light interference fit, and interference fit. The value of the allowance depends on which material is being used, how big the parts are, and what degree of tightness is desired. Such values have already been worked out in the past for many standard applications, and they are available to engineers in the form of tables, obviating the need for re-derivation. Therefore, if a loose fit is desired for a 3.175 mm shaft made of a particular grade of stainless steel, the engineer can look up the needed allowance in a reference book or computer program, rather than using a formula to calculate it. A flattened face together with a corresponding projection on the shank (not shown) could also be provided, which together with a resilient element such as a clip or similar could enable secure retention of the composite bit within the chuck. Prior to use, like all medical instruments, the composite drill must be sterilised—although this system easily adapts to the disposable, single use environment, typical of modern surgeries/health care centres, the sterilisation conveniently taking place during manufacture, by sterilisation by moist heat, gamma irradiation, and other methods, whereby sterile packed products are provided at said manufacturing facility. The drill together with a plastics shroud can easily be provided as a kit of parts for single use with a particular patient, as shall be discussed below. This would be advantageous in that a single use shroud would assist with any collection of biopsy material, since the drill can be placed in a biopsy package, without being required to be cleaned, possibly with loss of material. 
         [0039]      FIG. 4 d    shows a perspective view of a collet  408 , on its own; the four upstanding members  409  are clearly identifiable; the division of the otherwise circumferential body allowing flexing of the upstanding members outwardly.  FIG. 4 e    is a perspective view of the proximal end of the shroud and shows part of the chuck that, in use, is coupled with a type of device as shown in  FIG. 3  or be coupled to a flexible drive shaft, where a power tool arrangement is inconvenient, for example in veterinary applications. A flexible shaft can transmit rotary motion much like a solid shaft, but, it can be routed over, under, and around obstacles that would make using a solid shaft impractical. A flexible shaft assembly consists of a rotating shaft (sometimes called a core) with metal end fittings for attachment to mating parts. A protective outer casing is used when necessary. Notwithstanding this, torque reaction delay times may arise from motor stop to tool stop due to an inherent resilience in the drive shaft, which increases with increasing length of driveshaft.  FIG. 4 f    shows a composite drill  403  when in place in a power tool with the shroud removed.  FIG. 4 g    shows the drill assembly in outline, clearly showing the upstanding members  409  of the collet  408 , with the inwardly directed features  410 . 
         [0040]      FIG. 4 h    shows an example of an insertion tool  490  having a handle portion at a first end and a cylindrical aperture operable to enclose the shank of a drill bit assembly;  FIG. 4   hi  shows the tool in plan view;  FIG. 4   hii  shows the tool end on showing the a cylindrical bore.  FIGS. 4 i    and  FIG. 4 j    show how the drill assembly is inserted into the tool, whereby handling and positioning is simplified.  FIG. 4 k    shows how the assembly engages the chuck of the tool once the shroud has been removed. If the tool is made of plastics, then it can assist in protection of the drill during storage and transport and be part of a single-use system. Further features to assist in the loading and ejection of the drill bit from the chuck can be provided: for example, the packaging could include the holder may be provided with alignment markings, to assist loading of a drill bit and secure removal therefrom. A further feature or component of the packaging could assist in the provision of a seal for biopsy and to prevent potential cross-contamination issues, although standard stock control techniques should be maintained at all times. 
         [0041]      FIG. 5  shows how the aperture  406  of the shroud  402  engages with, in this example, a fingernail  300 , whereby to enable a secure, non-slip placement of the device and, therefore, reliable drilling of the nail.  FIG. 6 a    shows in cross-section how the annulus  406  abuts a nail plate  300 , whereby to stabilise the drilling system. The drill bit can conveniently be made from a variety of tool steels, as is known. It is preferred that the shroud has have a sharp tip (relative to the keratin) and can be made from metals that will not easily corrode and are suited to sterilisation such as hardened steel, stainless steel or aluminium that has been anodised to increase hardness. The shroud either as a whole or just about the tip can be made from a transparent or translucent material, whereby illumination from a light source within the shroud is possible or generally, to assist in viewing of the nail to be drilled. The form of the shroud should allow good visibility to a work piece and access to all areas (access to the nail root is critical in the treatment of onychomycosis). The annular aperture tip can include a pressure-sensitive sensor, whereby to enable control of a power source to the tool upon engagement of the annular aperture tip with a surface. The annulus tip member could be fitted to a plastics shroud or an aluminium shroud, although, it will be realised a multitude of materials can be employed, it being realised that the components need to be autoclavable or otherwise sterilised. Conveniently, the single use assembly prevents cross-infection and is sterilised sterilised during manufacture. 
         [0042]      FIGS. 6 b -6 d    show three different types of annulus in cross-section, which have sharp edges to enable an annulus to assist in engagement with a nail, to prevent slippage of one with respect to the other. The chuck is arranged so that it grips the collar  408  associated with the drill bit  302  by means of an interference fit. This provides a specific advantage in that, in the event the device that drills into the nail is knocked and the drill bit is forced off-axis with respect to a nail element, then the drill bit, in the event that it locks onto the nail rather than rotating with respect to the nail can slip within the chuck momentarily prior to the torque sensor preventing the motor from further rotation. 
         [0043]      FIG. 6 f    relates to a different form of shroud where alternatively or additionally a sharp substrate engaging tip is replaced with a rubber-like element that grips the surface. The rubber-like compound can be selected—though not necessarily restricted to materials made form or comprised of Suitable materials include, but may not be restricted to the following: a silicone rubber, a nitrile compound such as a hydrogenated nitrile compound, ethylene-propylene compounds, fluorocarbons, fluorosilicones, styrene-butadiene compounds, chloroprene compounds etc., the material being chosen because of its high-grip properties with respect to nail and nail-like substrates.  FIG. 6 g    shows a first alternative where the sharp substrate engaging tip is supplemented with a rubber-like compound. It will be appreciated that a rubber-like grip will not affect the surface of the nail in the same fashion as a sharp tip; it will be less painful in application of axially directed forces as the tool is used. The grip must be such that the torque reaction of the tool is taken into account and the nail is not damaged upon start-up of the tool. Specifically, with reference to  FIG. 6 f   , the shroud has a tip that comprises a rubber foot, which prevents slippage in normal use.  FIG. 6 g    shows a second further variation, where a tip has half rubber grip element  608  and half surface engaging tip  406 .  FIG. 6 h    shows the overall view from underneath, with the tip  406  defining a sharp edge on an inside of the tip. In contrast,  FIG. 6 i    shows a further shroud wherein the tip is half polymeric rubber foot and half a serrated tip  407 : this time the serrated tip lies on the outside of the tip member;  FIG. 6 j    shows how this appears form the underside. By having two types of surface grip/engagement means, the tool is quite adaptable to various conditions of tool. Sometimes the fungal nail will damage the substrate surface such that the entry of the surface of the nail substrate will actually be ineffective to a torque transfer upon start-up of the motor and so the use of a rubber part will assist in a satisfactory placement and maintenance in position of the tool which can therefore be most satisfactorily be held and retained by hand, enabling control by the clinician. 
         [0044]      FIG. 6 k    shows a still further variation, wherein the shroud  610  has a tip which lies in a plane that is not perpendicular to the axis of the drill  612 . This enables a drill to penetrate the nail or other material at an angle other than normal to a surface thereof, whereby to avoid damaging the cuticle, for example in the case of a human nail. 
         [0045]    A further significant advantage provided by this system is that new drill bits, of typically 1 mm in diameter, can be replaced simply by removing the shroud—conveniently located with a rubber O-ring about a part of the body of the tool—inserting the shank into a cylindrical aperture defined within a cylindrical chuck, a resilient collet engaging with an outside surface of the chuck—although other methods of fastening can be easily envisaged. The skilled man will readily appreciate the convenience: there is no possibility of any complication—substantial or otherwise—encountered when chuck key or hand-grip fastening procedures need to be deployed. Instead, a simple push on fit is provided by the collet of the shank gripping the chuck. A chuck is a specialized type of clamp used to hold an object, usually an object with radial symmetry, especially a cylindrical object, and are used most commonly used to hold a rotating tool (such as the drill bit in a power tool). Many chucks have jaws, which can be arranged in a radially symmetrical pattern (like the points of a star) to hold a tool or work-piece, although this does not prevent axial run-out, which is not normally an issue in, say household diy drilling projects, but will obviously have a significant effect when drilling nail, bone etc. since the tolerance corresponds in magnitude to the run-out in such chucks. Often the jaws will be tightened or loosened with the help of a chuck key—a wrench-like tool, typically with a circumferential gear arrangement for engagement with a corresponding radial tightening ring about the chuck. Keyless chucks are also available, their tightening and loosening being performed by hand force alone. Additionally, by having a simple unitary design, the chuck can be manufactured from materials that are sterilisation compatible or deliberately non-compatible in order to prevent reuse. 
         [0046]    Conveniently, single use components are provided with tools that assist in placement within a chuck, for example, in the provision of an alignment mechanism in association with the shroud. Such replaceable tools can comprise part of a treatment package whereby drill bits are provided together with receptacles to not only ensure safety in the provision of the tools but also to enable safe disposal, including the option of providing soiled drill bits and shank for biopsy examination. Conveniently, the shroud can be placed in a package for biopsy examination, in the event that the shroud enables collection of the swarf arising from drilling through a nail or other substrate. 
         [0047]    By having a shank of the drill bits of specific lengths, then control of penetration though particularly deep nail can be assisted and/or the extent of penetration is limited. The diameter of the aperture defined by the annulus is also variable, commensurate with the size of drill bit as shall be discussed below.  FIG. 6 e    shows a still further embodiment wherein the annulus  407  comprises a jagged edge. This design ensures engagement with nail plate, surface gripping features, stability features, forms a seal between a nail plate and the annulus tip, with advantages that can be realised in biopsy capture and drug delivery. 
         [0048]    Returning to  FIG. 4 e   , a perspective view of a distal end of a shroud is shown, which provides a volume  415  which can accommodate a number of features including, but not limited to, a vacuum system to assist in removal and possible storage of swarf form any associated drilling operations; storage for application of medicaments; placement of light sources etc.  FIG. 7  shows the relative sizes of a drill bit  302  within the nozzle of the shroud  406 , where an annular space is defined, which space can be used for biopsy collection, drug delivery, etc., although if the tolerance was tighter, the annulus could also act as a drill guide: the annular gap  702  can be critical for a particular function, given that if a drug is being delivered in reverse rotational mode i.e. acts as screw-feed for drug, which if supplied as a cream may have a viscosity which if delivered by any other means would not necessarily be present in the desired area by virtue of the presence of air-gaps. The use of free-flowing liquid medicaments means that medicament loss is great and therefore the overall treatment can be ineffective. The gap between the outside of the drill and the inside of the tube can be critical. Obviously, interfaces between relatively rotating parts are best provided with O-rings to prevent accumulation of unwanted debris, medicament or other products, or to provide a sealing feature, to ensure prevention of leakage of material; including but not restricted to biopsy material (to prevent cross-infection). 
         [0049]      FIG. 8  shows a still further variation, wherein the shroud  801  is provided with an aperture, which aperture can provide means for the delivery of drug and removal of debris by suction, or airflow towards nail. The present invention can overcome present problems encountered in the delivery of a drip-fed medicament as discussed above, by using the drill bit in reverse rotation, together with use of the as a feed for a medicament. A light source may be arranged within or about the shroud, to assist in illuminating the drilling area. 
         [0050]    In accordance with a further aspect of the invention, there is provided a work-piece jig  901  which cooperates with the annular tip of the shroud  406  to ensure accurate placement of the drill bits using the rotary tool of the invention, under manual control with respect to a nail  300 . Referring to  FIG. 9 a   , a section through the jig  901  shows guide channels  902  for use in enabling drill bits to accurately be placed with respect to the nail.  FIG. 9 b    shows the jig at 90° to jig  901  with respect to the view shown in  FIG. 9 a   , together with the tip of the shroud  406  engaging with the top surface of the jig. Not shown, but an apertured button top, can be arranged so that the tip can couple with the jig, to enable repeatable drilling, with the jig also being provided with conduits  904  and  905  for the introduction of air whereby to clear swarf, for example, or for the introduction of a medicament, with the conduit  905  for the removal of biopsy-swarf. Channels  904  and  905  are optional and can be placed independently of one another. The jig can be placed upon the nail surface; the use of glues across the whole of a nail surface is not recommended, but by the placement of locating dots  908  upon a nail surface, attached by a suitable glue, such as a cyanoacrylate glue, then the jig can be located with respect to the nail. 
         [0051]    With reference to  FIG. 9 c   —the locating dots, retained by glue in confined areas at four points on the nail surface ensure that the jig is securely located, with the underside of the jig having corresponding locating means associated complementary to the locating dots. After the jig has been successfully been employed to enable the rotary to drill into the nail under the hand-held (manual) control of an operator, collect biopsy material and deliver medicament as appropriate, then a false nail  907 , also with complementary locating dots  910  can be placed upon the nail, to protect and seal the area—to the level required for the particular condition of the nail. Other forms of false nail can be employed, with channels for the provision of medicament over time. It will be appreciated that different jigs and false nails having different widths and arcs of curvature will be required to accommodate the differing nature of human beings. It can be envisioned, without departing from the invention, that many variations are possible. 
         [0052]      FIG. 10  shows a further embodiment  422  wherein a fan assembly  1011  is present, placed a short axial distance from collar  408  comprises four blades  1012 , arranged to provide a relative vacuum at the nozzle  406  upon rotation indicated by reference numeral  1013 . Arrow  1006  indicates the direction the air and debris flow from the nozzle; Air indicated at  1016  exits the motor unit through aperture  1015  defined in the wall of the casing  405 . The addition of a fan or fan blades to the rotating component generates an airflow whereby debris is removed from the drilling site. The fan may be included or separate to the clip used to retain the drill bit within the drive shaft. Conveniently, a tube is fastened to the aperture  1015  by way of a coupling member or otherwise whereby the air plus nail debris can be guided away. 
         [0053]    Ideally, there is also provided a trap or other containment system, whereby the debris can be removed from the airflow and collected for biopsy use. The tube can lead to a collection trap.  FIG. 11 a    shows a simple trap whereby debris is deposited either by virtue of changing air velocity and the Bernoulli effect or upon the air flow hitting a baffle member. Preferably, and in accordance with the system shown in  FIG. 11 b   , a filter system is provided whereby the debris is collected on the inside face of the filter or drops down into a containment area. The trap is ideally easily removable to enable simple collection of the debris. By having the fan removed with the drill bit, single use of the fan ensures that cross contamination is reduced. Conveniently, an inner duct (not shown) is provided whereby the duct, tube and fan are removed together with the shroud  402 ; after use all are removed from the drill tool. 
         [0054]    The rotary tool can also be provided with a window or is either transparent or translucent, whereby the hard animal tissue substrate to be drilled can be viewed through the shroud. Conveniently, the shroud is provided with a light source, whereby to illuminate the hard animal tissue substrate to be drilled. Preferably, the light source is a broad spectrum light source that can also provide germicidal ultra-violet (UV) light, whereby to provide irradiation treatment, in addition to the provision of a medicament. It will be appreciated that the effectiveness of germicidal ultra-violet light in such an environment depends on a number of certain factors: the length of time a micro-organism is exposed to ultra-violet light, the presence of particles that can protect the micro-organisms from ultra-violet light, and a micro-organism&#39;s ability to withstand ultra-violet light during its exposure. Further, the effectiveness of this form of sterilization can be dependent upon line-of-sight exposure of the micro-organisms to the ultra-violet light; dirt from a debris-removal airflow upon a lamp can reduce effective light output, whilst poor lamp cooling under the airflow can also detrimentally affect ultra-violet light output. Accordingly, the light source can conveniently be placed such that impingement of the lamp with any airflow does not occur, for example by use of a shield for the lamp together with a parabolic reflector. It should also be recognised that in use, such bulbs require annual replacement and scheduled cleaning to ensure effectiveness. Conveniently, the window of the shroud or the transparent/translucent material of the shroud is not transparent to the ultra-violet light. 
         [0055]    As is known, per WO2013098555 in the name of the inventor of present invention, the drill system employs torque sensitive sensors whereby drilling is stopped after drilling through the nail has completed, prior to penetration into the nail bed. The system uses a drilling procedure that allows the motor to be started once the shroud has been securely located and a pressure switch has been activated. The forces can be measured using various sensors, for example. 
         [0056]    Whilst the present invention has been described solely with reference to matters of onychomycosis in the nails of human beings, the ambit of overall uses is not so limited. The present invention can be used, for example, in the collection of biopsy matter, drug delivery, subungual haematoma, animal claws, skulls e.g. hydrocephalus.