Abstract:
In the context of bone surgery and in particular arthroscopic surgery, there is frequently a need for the application of “percussive force” to the distal end component(s) of a surgical device, i.e., repetitive percutient or striking force analogous to that of a hammer driving a nail. Disclosed herein are mechanisms and methods for automating and/or controlling the application of such a percussive force so as to avoid the present need in the art for a “third hand”. The present invention addresses the significant and long felt need by providing a powered percussive driver device that may be controlled directly by the primary surgeon.

Description:
PRIORITY 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/964,180 filed Dec. 26, 2013, the contents of which are hereby incorporated by reference in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to the field of endoscopic surgery and powered surgical instruments for use therein. More particularly, the invention relates to a minimally invasive endoscopic percussive driver for producing indentations in bony surfaces or driving implants into bone. In the context of the present invention, the rotational motion of a device such as an arthroscopy shaver handpiece is converted into percussive energy usable for surgical applications. 
       BACKGROUND OF THE INVENTION 
       [0003]    Many surgical procedures, and in particular arthroscopic surgeries, require the application of “percussive force”, i.e., repetitive percutient or striking force. In the typical case, the percussive force (or energy) is supplied by a mallet striking a proximal portion of a device requiring such application, such as a surgical awl. In a first instance the percussive force may be required to drive the distal portion of the awl into a bony surface so as to form the recesses required for the microfracture treatment of an articular lesion. In another instance, the percussive force may be applied to the proximal end of a driver used to place an interference plug implant (also called an “anchor”) for the purpose of securing a tissue graft to a bony surface. In the context of arthroscopic surgery, the surgeon often needs to manipulate an endoscope so as to maintain visualization of the surgical site while also controlling a device introduced for its clinical effect. As a result, both hands of the surgeon are usually occupied and thus it is necessary that a third hand to apply the percussive force (e.g., the mallet to the device) to achieve the desired clinical effect. This has certain distinct drawbacks. First of all, it means that every surgery requires a minimum of a surgeons plus a skilled medical professional. Second, application of an external percussive force, especially in the form of a striking mallet, by another person places the surgeon&#39;s hands at some risk for injury. Finally, the degree of precision of the result may be compromised by the application of excess force by the mallet wielder. 
         [0004]    Accordingly, there is a need for a powered percussive loading device that may be controlled directly by the primary surgeon. The present invention addresses this significant and long felt need by providing a control mechanism, for example in the form of a foot pedal or hand control on the interventional surgical device itself. 
       SUMMARY OF THE INVENTION 
       [0005]    A primary goal of the present invention is to provide means and methods for automating and/or controlling the application of the requisite percussive force that frequently accompanies surgical procedures, such as arthroscopic surgeries, so as to avoid the present need in the art for the “third hand” in such context. To that end and accordance with that goal, it is an objective of the present invention to provide a percussive surgical device, for example as herein described and comprising:
       a. an outer assembly characterized by (i) a proximal outer hub having proximal and distal ends, wherein the proximal end of the outer hub includes a first cooperating element, and (ii) a distal tubular portion having proximal and distal ends and an elongate lumen extending therebetween, wherein the proximal end of the distal tubular portion is configured to the distal end of the outer hub and the distal end of the distal tubular portion includes a distally projecting penetrating element positioned and axially movable within the elongate lumen; and   b. an inner assembly characterized by (i) a proximal inner hub having proximal and distal ends, wherein the proximal end of the inner hub includes a drive portion for transmitting rotational motion from an external shaver handpiece to the inner assembly, and the distal end of the inner hub includes a second cooperating element that engages the first cooperating element, and (ii) a distal portion comprising an elongate driving rod slidably positioned and rotationally and axially movable within the elongate lumen of the distal tubular portion of the outer assembly;
 
wherein:
   the proximal end of the outer hub is connected to the distal end of the inner hub; and   the drive portion of the inner hub further comprises an elastic member that transmits an axial force distally on the inner member to maintain the engagement of the first and second cooperating elements when the inner member hub and outer member hubs are connected;
 
whereby:
   rotation of the inner assembly relative to the outer assembly drives an interaction between the first and second cooperating elements which causes the inner assembly to move axially from a first extended position to a second retracted position while simultaneously compressing the elastic member; and   rotation of the respective inner and outer assemblies past a pre-determined stop limit results in a release of the compressed elastic member, which, in turn, propels the inner assembly in distal direction such that the distal end of the driving rod strikes the proximal end of the distally projecting penetrating element with a percussive force sufficient it to move axially in the distal direction.       
 
         [0012]    It is a further objective of the present invention to provide a percussive arthroscopic shaver assembly, for example as herein described and comprising an arthroscopy shaver handpiece having a distal end defining the opening of a central lumen and a proximal end characterized by a rotational drive element, assembly to the above-described percussive surgical device, wherein the outer assembly is received with the central lumen such that rotation of the distal rotational drive element causes rotation of the inner assembly. 
         [0013]    It is yet a further objective of the present invention to provide a method for producing a plurality of microfractures in a bony surface in a patient in need thereof using, for example, the above-described percussive arthroscopic shaver assembly, for example as herein described and comprising the following steps:
       a. introducing the percussive arthroscopic shaver assembly into a target surgical site comprising the bony surface of interest;   b. positioning the distally projecting penetrating element of the outer assembly of the percussive surgical device against the bony surface;   c. rotating the distal rotational drive element of the arthroscopic shaver handpiece so as to cause rotation of the inner assembly relative to the outer assembly, which, in turn, causes the inner assembly to axially move from a first extended position to a second retracted position while simultaneously compressing the elastic member;   d. continuing to rotate the respective inner and outer assemblies past a pre-determined stop limit so as to cause release of the elastic member, which, in turn, propels the inner assembly in distal direction such that the distal end of the driving rod strikes the proximal end of the distally projecting penetrating element with a percussive force sufficient it to move axially in the distal direction; and   e. repeating steps (c) and (d) as needed until a plurality of microfractures are formed in the bony surface.
 
Such a method finds utility in connection with arthroscopic knee repair, for example.
       
 
         [0019]    Aspects and embodiments of the present invention in accordance with the afore-noted objectives are as follows: 
         [0020]    In a first aspect, the present invention relates to a surgical device and method for converting the rotary motion of a conventional shaver handpiece to percussive energy, which is then transmitted to an axially movable distal element. In an illustrative embodiment, such a device has an elongate distal portion housing the interventional component(s) and a proximal portion that includes inner and outer hubs for removable mounting of the device to the handpiece. 
         [0021]    In a particularly preferred embodiment, a proximal portion of the outer hub has formed thereon a helical cam element with proximally facing cam surfaces that coordinates with mating cam surface(s) on a distal portion of the inner hub. Distal surface(s) of the inner hub are configured to follow the cam surface of the outer hub so as to create axial relative motion between the inner and outer hubs and the assemblies to which they are affixed. A spring mounted to the device provides the distal axial force between the inner hub and handpiece necessary to maintain contact between the cam and follower surfaces of the inner and outer hubs. The cam components are constructed such that rotation of the inner member causes compression of the spring to a predetermined limit whereupon further rotation allows the inner assembly to freely advance distally, propelled by the compressed spring. In this manner, rotational energy supplied to the device by the handpiece is converted to stored energy in the spring, and, upon release by the cam, to kinetic energy as the inner assembly is propelled distally by the spring force. Distal to the inner hub and affixed thereto is an inner assembly that includes an elongate rod member of predetermined mass. Coaxial with the elongate rod member of the inner assembly is an outer assembly that includes an outer tubular member having a proximal end attached to the outer hub and a distal end that includes a cannulated element affixed thereto. Positioned within the lumen of the distal end cannulated element is an axially movable distal element that freely moves between a first proximal position and a second distal position. When in the second distal position, the distal end of the axially movable distal element protrudes beyond the distal limit of the cannulated element. The protruding distal end of the axially movable distal element may optionally be configured for penetration into a bony surface, or, alternatively, may be configured for transmitting percussive energy to an implant that is to be inserted into bone. The maximum travel of the axially movable element between its first proximal position and second distal position (i.e., between its proximal and distal limits) is configured to be less than the travel of the inner assembly within the outer assembly caused by the cooperative interaction of the cam and follower. Because of this, the inner assembly rod element travels freely and is accelerated by the stored spring force until the distal end of the rod element contacts the proximal end of the axially movable distal element of the outer assembly so as to percussively transmit energy thereto. If the distal portion of the axially movable distal element is configured for penetration of bone and the distal end thereof is in contact with a bony surface, the repeated application of this percussive force will cause incremental penetration of the distal portion of the movable element into the bone, much like repeated strikes against a hammer drive the insertion of a nail into a substrate of interest. Alternatively, if the distal portion of the axially movable distal element is configured for the placement of an implant, incremental distal advancement of the implant into the bone will occur. In either case, the device of the present invention adaptively converts the rotational energy of the shaver handpiece first to stored spring energy, then to kinetic energy of a rod element that is percussively applied to the proximal side of the axially movable distal element where it is then dissipated in achieving a desired clinical effect. The percussive energy that may be dissipated in achieving the clinical effect is limited by the maximum axial travel of the inner assembly within the shaver handpiece and by the maximum constant of the spring that can be compressed by the shaver handpiece. In this manner, both the duration and power of the percussive force may be strictly controlled so as to avoid damage (to the patient or the surgeon) that can result from overstrike. 
         [0022]    A second aspect of the present invention relates to a percussive surgical system that includes a removable device for transmitting percussive energy to an axially movable distal element, and a handpiece configured to provide percussive energy to the device. Because the percussive energy source is a handpiece designed for the production of percussive energy, the limitations on maximum percussive energy available for producing clinical effects due to the use of a shaver handpiece are eliminated. Such a system finds particularly utility in the context of clinical applications that require greater percussive energy. For instance, devices of the instant invention system may be used to produce holes having non-circular geometries that cannot be produced by a rotary drill. Such holes may be used as sockets for the placement of implants having optimized non-radial forms. 
         [0023]    These and other aspects are accomplished in the invention herein described, directed to a powered percussive surgical device. Further objects and features of the invention will become more fully apparent when the following detailed description is read in conjunction with the accompanying figures and examples. To that end, other embodiments of the percussive surgical device of the present invention may include or utilize manual instruments that convert energy input by the surgeon to percussive energy applied to a distal element. For example, in one such embodiment, a force applied by the surgeon to an element of the device may compress an elastic member, such as a coil spring, that is attached to an axially movable weight. When the elastic element reaches a predetermined degree of compression, the compression mechanism is released so as to allow the weight to travel distally, propelled by energy supplied by the elastic member. The weight continues distally until striking a distal element thereby transferring percussive energy thereto. However, it is to be understood that both the foregoing summary of the invention and the following detailed description are of a preferred embodiment, and not restrictive of the invention or other alternate embodiments of the invention. In particular, while the invention is described herein with reference to a number of specific embodiments, it will be appreciated that the description is illustrative of the invention and is not constructed as limiting of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0024]    Various aspects and applications of the present invention will become apparent to the skilled artisan upon consideration of the brief description of figures and the detailed description of the present invention and its preferred embodiments that follows: 
           [0025]      FIG. 1  depicts an illustrative outer assembly for a surgical percussive driver constructed in accordance with the principles of this invention. 
           [0026]      FIG. 2  is a side elevational view of the objects of  FIG. 1 . 
           [0027]      FIG. 3  is a side elevational sectional view of the objects of  FIG. 1  at location A-A of  FIG. 2 . 
           [0028]      FIG. 4  is an expanded side elevational sectional view of the objects of  FIG. 1  at location A-A of  FIG. 1 . 
           [0029]      FIG. 5  is a perspective view of the objects of  FIG. 1 . 
           [0030]      FIG. 6  is an expanded view of the proximal portion of the objects of  FIG. 5 . 
           [0031]      FIG. 7  is a plan view of an illustrative inner assembly for a surgical percussive driver constructed in accordance with the principles of this invention. 
           [0032]      FIG. 8  is a side elevational view of the objects of  FIG. 7 . 
           [0033]      FIG. 9  is an expanded side elevational sectional view of the proximal portion of the objects of  FIG. 7  at location A-A of  FIG. 8 . 
           [0034]      FIG. 10  is a distal perspective view of the objects of  FIG. 7 . 
           [0035]      FIG. 11  is an expanded view of the proximal portion of the objects of  FIG. 10   
           [0036]      FIG. 12  is a proximal perspective view of the objects of  FIG. 7 . 
           [0037]      FIG. 13  is an expanded proximal axial view of the objects of  FIG. 7 . 
           [0038]      FIG. 14  is a distal perspective view of an illustrative surgical percussive driver constructed in accordance with the principles of this invention, including the inner assembly of  FIG. 7  fitted with the outer assembly of  FIG. 1 . 
           [0039]      FIG. 15  is a proximal perspective view of the objects of  FIG. 14 . 
           [0040]      FIG. 16  is a plan view of the objects of  FIG. 14 . 
           [0041]      FIG. 17  is an expanded elevational sectional view of the distal portion of the objects of  FIG. 16  at location A-A of  FIG. 16 . 
           [0042]      FIG. 18  is an expanded elevational sectional view of the proximal portion of the objects of  FIG. 16  at location B-B of  FIG. 16 . 
           [0043]      FIG. 19  is a proximal perspective view depicting a surgical percussive driver constructed in accordance with the principles of this invention, such as depicted in  FIG. 14 , mounted in the distal portion of a conventional arthroscopy shaver handpiece, with the inner assembly coupled to the drive mechanism of the handpiece, and in its retracted (first proximal) position. 
           [0044]      FIG. 20  is a distal perspective view of the objects of  FIG. 19 . 
           [0045]      FIG. 21  is a side elevational view of the objects of  FIG. 19 . 
           [0046]      FIG. 22  is a plan sectional view of the objects of  FIG. 19  at location A-A of  FIG. 21 . 
           [0047]      FIG. 23  is a plan view of the objects of  FIG. 19 . 
           [0048]      FIG. 24  is an expanded side elevational sectional view of the distal portion of the objects of  FIG. 23  at location B-B of  FIG. 23 . 
           [0049]      FIG. 25  is an expanded side elevational sectional view of the proximal portion of the objects of  FIG. 23  at location C-C of  FIG. 23 . 
           [0050]      FIG. 26  is a plan view of the objects of  FIG. 19  with the inner assembly in the advanced (second distal) position. 
           [0051]      FIG. 27  is a side elevational sectional view of the objects of  FIG. 26  at location A-A of  FIG. 26 . 
           [0052]      FIG. 28  is a side elevational view of the objects of  FIG. 26 . 
           [0053]      FIG. 29  is an expanded plan sectional view of the distal portion of the objects of  FIG. 28  at location B-B of  FIG. 28 . 
           [0054]      FIG. 30  is an expanded plan sectional view of the proximal portion of the objects of  FIG. 28  at location C-C of  FIG. 28 . 
           [0055]      FIG. 31  is a perspective view depicting a surgical percussive driver constructed in accordance with the principles of this invention, such as depicted in  FIG. 14 , mounted in the distal portion of an arthroscopy shaver handpiece, such as depicted in  FIG. 19 , and positioned for microfracture treatment of an articular lesion. 
           [0056]      FIG. 32  is an expanded mid-line sectional view of the distal portion of the elements of  FIG. 31 . 
           [0057]      FIG. 33  is a perspective view of the elements of  FIG. 31  at the beginning of percussive penetration of the bony surface of the lesion. 
           [0058]      FIG. 34  is an expanded mid-line sectional view of the distal portion of the elements of  FIG. 33   
           [0059]      FIG. 35  is a perspective view of the elements of  FIG. 31  at completion of percussive penetration of the bony surface of the lesion. 
           [0060]      FIG. 36  is an expanded mid-line sectional view of the distal portion of the elements of  FIG. 35 . 
           [0061]      FIG. 37  is a perspective depiction of the articular lesion at completion of microfracture treatment using a percussive surgical instrument of the instant invention. 
           [0062]      FIG. 38  is a perspective view of an alternate embodiment of the instant invention as illustrated in  FIG. 19  in which the distal end is configured for forming flat regions on bony surfaces. 
           [0063]      FIG. 39  is an expanded view of the distal portion of the elements of  FIG. 38  at location A. 
           [0064]      FIG. 40  is a perspective view of an alternate embodiment of the instant invention as illustrated in  FIG. 19  in which the distal end is configured for forming grooves in bony surfaces. 
           [0065]      FIG. 41  is a perspective view of an alternate embodiment of a percussive surgical device of the instant invention that is configured for the placement of an interference plug type suture anchor with a loading loop in place for the loading of sutures into the device. 
           [0066]      FIG. 42  is a plan view of the objects of  FIG. 41 . 
           [0067]      FIG. 43  is a side elevational view of the objects of  FIG. 41 . 
           [0068]      FIG. 44  is a plan view of the objects of  FIG. 41 . 
           [0069]      FIG. 45  is an expanded sectional view of the objects of  FIG. 44  at location B-B. 
           [0070]      FIG. 46  is a perspective view of the embodiment of  FIG. 41  with sutures loaded into the device. 
           [0071]      FIG. 47  is a plan view of the objects of  FIG. 46 . 
           [0072]      FIG. 48  is a side elevational view of the objects of  FIG. 46 . 
           [0073]      FIG. 49  is an expanded sectional view of the objects of  FIG. 47  at location A-A. 
           [0074]      FIG. 50  is a schematic representation of the first step in a procedure for the placement of an interference plug type suture anchor for the purpose of affixing a tissue graft using the embodiment of the instant invention depicted in  FIGS. 41 through 49 . 
           [0075]      FIG. 51  is a schematic representation of the second step in a procedure for the placement of an interference plug type suture anchor for the purpose of affixing a tissue graft. 
           [0076]      FIG. 52  is a schematic representation of the third step in a procedure for the placement of an interference plug type suture anchor for the purpose of affixing a tissue graft. 
           [0077]      FIG. 53  is a schematic representation of an interference plug type suture anchor placed using the embodiment of the instant invention at the completion of the placement process. 
           [0078]      FIG. 54  is a distal perspective view of an alternate embodiment device of the instant invention for use with a handpiece that provides axial percussive energy rather than rotational energy as in the previous embodiments. 
           [0079]      FIG. 55  is an expanded view of the distal portion of the objects of  FIG. 54 . 
           [0080]      FIG. 56  is a distal axial view of the objects of  FIG. 54 . 
           [0081]      FIG. 57  is a plan view of the objects of  FIG. 54 . 
           [0082]      FIG. 58  is a side elevational view of the objects of  FIG. 54 . 
           [0083]      FIG. 59  is an expanded sectional view of the objects of  FIG. 57  at location C-C. 
           [0084]      FIG. 60  is an expanded sectional view of the objects of  FIG. 57  at location B-B. 
           [0085]      FIG. 61  is a plan view of the embodiment of  FIG. 54  with elements of a handpiece configured to supply percussive energy to the device, and with the device in its retracted (first proximal) position. 
           [0086]      FIG. 62  is an expanded sectional view of the objects of  FIG. 61  at location A-A of  FIG. 61 . 
           [0087]      FIG. 63  is an expanded sectional view of the objects of  FIG. 61  at location B-B of  FIG. 61 . 
           [0088]      FIG. 64  is a plan view of the embodiment of  FIG. 54  with elements of a handpiece configured to supply percussive energy to the device, and with the device in its advanced (second distal) position. 
           [0089]      FIG. 65  is an expanded sectional view of the objects of  FIG. 64  at location A-A of  FIG. 64 . 
           [0090]      FIG. 66  is an expanded sectional view of the objects of  FIG. 64  at location B-B of  FIG. 64 . 
           [0091]      FIG. 67  is a perspective view of the distal portion of an alternate embodiment device of the instant invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0092]    Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, the preferred methods, devices, and materials are now described. However, before the present materials and methods are described, it is to be understood that the present invention is not limited to the particular sizes, shapes, dimensions, materials, methodologies, protocols, etc. described herein, as these may vary in accordance with routine experimentation and optimization. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope of the present invention which will be limited only by the appended claims. Accordingly, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. However, in case of conflict, the present specification, including definitions below, will control. 
         [0093]    In the context of the present invention, the following definitions apply: 
         [0094]    The words “a”, “an” and “the” as used herein mean “at least one” unless otherwise specifically indicated. Thus, for example, reference to an “opening” is a reference to one or more openings and equivalents thereof known to those skilled in the art, and so forth. 
         [0095]    The term “proximal” as used herein refers to that end or portion which is situated closest to the user of the device, farthest away from the target surgical site. In the context of the present invention, the proximal end of the powered percussive device includes the hub region. 
         [0096]    The term “distal” as used herein refers to that end or portion situated farthest away from the user of the device, closest to the target surgical site. In the context of the present invention, the distal end of the powered percussive device includes the axially movable distal element optionally configured for penetration of a bony surface. 
         [0097]    In the context of the present invention, the term “cannula” is used to generically refer to the family of elongate lumened surgical instruments that facilitate access across tissue to an internally located surgery site. 
         [0098]    The terms “tube” and “tubular” are interchangeably used herein to refer to a generally round, long, hollow component having at least one central opening often referred to as a “lumen”. 
         [0099]    The terms “lengthwise” and “axial” as used interchangeably herein to refer to the direction relating to or parallel with the longitudinal axis of a device. The term “transverse” as used herein refers to the direction lying or extending across or perpendicular to the longitudinal axis of a device. 
         [0100]    The term “lateral” pertains to the side and, as used herein, refers to motion, movement, or materials that are situated at, proceeding from, or directed to a side of a device. 
         [0101]    The term “medial” pertains to the middle, and as used herein, refers to motion, movement or materials that are situated in the middle, in particular situated near the median plane or the midline of the device or subset component thereof. 
         [0102]    The term “rotational” as used herein refers to the revolutionary movement about the center point or longitudinal axis of the device. In the context of the present invention, the inner assembly is rotated relative to the outer assembly, which typically is held in a stationary position, or vice versa. In either case, the rotary motion results in an energy potential that is stored and then subsequently transformed into an axial percussive force having clinical utility. 
         [0103]    In the Summary above and the Examples below, the present invention makes reference to the use of a linear spring to store and subsequently release kinetic energy in the form of a percussive force. However, the present invention contemplates other compressible and/or elastomeric configurations for potential energy storage, i.e., alternative mechanisms, such as a bow or torsional spring, that may be deformed under pressure, tension or compression (i.e., stressed) and then subsequently released from stress, thereby transforming the stored energy into a kinetic energy that may be directed to a target location or component as a percussive force. 
         [0104]    In the Examples below, the present invention makes reference to various lock-and-key type alignment mechanisms that serve to establish and secure the arrangement of the various device components, such as the outer assembly to the arthroscopy handpiece. It will again be readily understood by the skilled artisan that the position of the respective coordinating elements (e.g., mating slots and protrusions) may be exchanged and/or reversed as needed. 
         [0105]    In the Summary above and the Examples below, the present invention makes reference to a “cam” and “cam surfaces”. In the context of the present invention, a cam is a rotating or sliding piece in a mechanical linkage used especially in transforming rotary motion into linear motion or vice-versa. It is often a part of a rotating wheel (e.g. an eccentric wheel) or shaft (e.g. a cylinder with an irregular shape) that strikes a lever at one or more points on its circular path. The cam can be a simple tooth, as is used to deliver pulses of power to a steam hammer, for example, or an eccentric disc or other shape that produces a smooth reciprocating (back and forth) motion in the follower, which is a lever making contact with the cam. 
         [0106]    The present invention contemplates the use of alternative cooperating elements for automatically transmitting relative axial movement when the inner and outer hubs are relatively rotated, in particular cooperating elements disposed on or within the inner and outer hubs. Examples of such cooperating elements include, but are not limited to, screw threads, worm gears, worm wheels, pneumatic devices, hydraulic mechanisms, magnetic assemblies, ratchet-and-pawl assemblies, and push-pull connectors. 
         [0107]    The instant invention has both human medical and veterinary applications. Accordingly, the terms “subject” and “patient” are used interchangeably herein to refer to the person or animal being treated or examined. Exemplary animals include house pets, farm animals, and zoo animals. In a preferred embodiment, the subject is a mammal. 
         [0108]    Hereinafter, the present invention is described in more detail by reference to the Figures and Examples. However, the following materials, methods, figures, and examples only illustrate aspects of the invention and are in no way intended to limit the scope of the present invention. For example, while the present invention makes specific reference to arthroscopic procedures, it is readily apparent that the teachings of the present invention may be applied to other minimally invasive procedures and are not limited to arthroscopic uses alone. As such, methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. 
       Examples 
       [0109]      FIGS. 1 through 6  depict an outer assembly  200  for a surgical percussive driver constructed in accordance with the principles of this invention. Assembly  200  has a polymeric proximal portion forming a hub  202  with alignment key  203  for mounting in an arthroscopy shaver handpiece. A tubular cam element  204  having a helically formed proximal surface is mounted in the proximal end of hub  202 . Outer assembly  200  has a distal tubular portion  206  terminating in a distal sub-assembly having a fixed portion  208  mounted to the distal end of tubular portion  206  and an axially movable portion formed of distal penetrating element  210  together with tubular retaining element  212  mounted to the proximal end of element  210  that acts as a stop mechanism, preventing the dislodgment or removal of the penetrating element  210  from the lumen of tubular portion  206 . Distal penetrating element  210  can move axially distance  220  within element  208 . 
         [0110]      FIGS. 7 through 16  depict an inner assembly  300  for a surgical percussive driver constructed in accordance with the principles of this invention. Assembly  300  has a proximal portion including a polymeric hub  320  with a proximal end drive portion  324  for transmitting rotational motion provided by an arthroscopy shaver handpiece, and a distal portion  322  in which is mounted the proximal end  312  of metallic distal rod element  310 , distal rod element  310  having a distal end  314 . Hub  320  has mounted to its proximal drive portion spring  340  which has an initial compression supplied by, and is maintained in its position by spring retainer  350 . Hub  320  has a helical distal-facing surface  326  having a pitch equal to that of the helical proximal surface of cam element  204  ( FIGS. 1 through 6 ). 
         [0111]      FIGS. 14 through 18  depict a surgical percussive driver  100  formed in accordance with the principles of this invention and formed of outer assembly  200  and inner assembly  300 . Distal rod portion  310  of inner assembly  300  is positioned within tubular distal portion  206  of outer assembly  200  such that inner assembly  300  may be moved axially and rotationally, the axial motion being provided by cooperative interaction of the helical surface of cam  204  of outer assembly  200  and distal helical surface  326  of inner hub  320 . The respective helical surfaces ( 204  and  326 ) are formed such that rotation of inner assembly  300  within outer assembly  200  causes proximal axial motion of inner assembly  300  a predetermined distance whereupon inner assembly  300  is allowed to return to its distal-most position as depicted in  FIGS. 16 through 18 . In this distal-most advanced position, metallic distal rod portion forces pointed penetrating element  210  to a distal position, though not its distal-most position. 
         [0112]      FIGS. 19 through 25  present a schematic representation of surgical percussive driver  100  (formed through the coordination of inner and outer assemblies,  300  and  200  respectively) mounted in a conventional arthroscopy shaver handpiece, wherein only those portions of the handpiece essential to the understanding of the operation of device  100  are depicted. Accordingly, fixed element  402  with keyway  403 , and rotatable element  404  with keyway  405  are distal elements of a shaver handpiece. In use, rotatable element  404  is positioned such that keyways  403  and  405  are aligned and hub  202  with alignment key  203  can be inserted and positioned as shown in  FIG. 25 , whereupon rotatable element  404  is repositioned such that keyways  403  and  405  are not aligned and the axial position of hub  202  is maintained in the handpiece. Element  410  corresponds to the rotational drive element of the shaver handpiece. As best seen in  FIG. 22  proximal end drive portion  324  of hub  320  is engaged by slot  412  of drive element  410 , and the tapered proximal portion of spring retainer  350  engages the tapered distal portion of drive element  410  such that inserting device  100  into the handpiece causes compression of spring  340 . The compression of spring  340  is depicted at its near maximum in  FIGS. 19 through 25  wherein, as best seen in  FIG. 21 , the helical proximal surface of cam  204  in cooperative action with helical distal surface  326  of hub  320  has positioned inner assembly  300  at its maximum proximal deflection. Referring to  FIG. 24 , distal rod portion  310  of inner assembly  300  is positioned proximally a distance  520  from the proximal end of penetrating element  210  and retaining element  212 . As shown in  FIG. 24 , penetrating element  210  is in its proximal-most position with distance  510  between the distal-most surface of retaining element  212  and the proximal-most surface of element  208 . Distance  520  is less than the maximum proximal deflection of inner assembly  300  caused by the cooperative action of cam  204  and surface  326  of hub  320 . Distances  510  and  520  together are greater than the maximum proximal deflection of inner assembly  300  caused by the cooperative action of cam  204  and surface  326  of hub  320 . 
         [0113]      FIGS. 26 through 30  depict the same elements as  FIGS. 19 through 25  except that, as best seen in  FIG. 26 , inner assembly  300  has been rotated such that the helical proximal surface of cam  204  and helical surface  326  of hub  320  are disengaged and inner assembly  300  has traveled to its distal-most position as determined by cam  204  and inner hub  320 . When helical surface  326  of hub  320  is rotated past the angular limit of the helical proximal surface of cam  204 , force exerted by the (now released) spring  340  causes inner assembly  300  to rapidly travel to its distal limit. Potential energy stored in spring  340  (i.e., kx where k is the spring constant and x is the spring deflection) is converted to kinetic energy (i.e., ½ mv 2  where m is the mass of the inner assembly and v is the velocity of the inner assembly). As best seen in  FIG. 29 , the distal end of distal rod  310  of inner assembly  300  contacts the proximal end of penetrating element  210  forcing it distally distance  530 . 
         [0114]    In use, the pointed distal end of penetrating element  210  is positioned against a bony surface to be penetrated. The shaver handpiece is activated such that inner assembly  300  is rotated, with cam  204  and helical surface  326  of hub  320  causing inner assembly  300  to be repeatedly deflected proximally and allowed to “snap” back to its distal position, in the process transferring its kinetic energy to the penetrating element so as to cause iterative penetration of the bony surface. Device  100  depicts only two such cycles per revolution of inner assembly  300 . However, this is meant to be illustrative only; as such other embodiments are contemplated wherein the axial cycles per revolution may range from 1 to 5, preferably 2 to 4, more preferably 2 to 3. 
         [0115]    The energy transferred to penetrating element  210  is determined by the spring constant of spring  340 . Accordingly, the spring constant can be increased to maximize the energy transferred, the maximum spring constant being determined by the torque required to rotate the inner so as to result in compression of spring  340 . The torque required will be determined by the spring constant and by the helical pitch of cam  204  and helical surface  326  of hub  320 . This pitch can be minimized by having a single compression of the spring per rotation of inner assembly  300 . To increase the rate of penetration of penetrating element  210  into a bony surface, the speed of the handpiece can be increased. The mass of inner assembly  300  ideally should not affect the transfer of the stored spring energy since a lower mass would result in a correspondingly higher velocity; however, the efficiency of the transfer of the kinetic energy and penetration of the bony surface at high velocities may be less efficient. Accordingly, the velocity may be decreased by increasing the mass of distal rod  310  of inner assembly  300  either through maximizing its diameter and length, or by forming it from a high-density metal. 
         [0116]    In the embodiment above, spring  340  is retained on inner hub  320  by spring retainer  350 . In other embodiments a spring is incorporated in the shaver handpiece and spring  340  and spring retainer  350  are eliminated. 
         [0117]    In the illustrative embodiment herein depicted, the penetrating element  210  and distal rod  310  are coaxial. However, other embodiments are anticipated in which the axis of the penetrating element  210  is angularly offset from the axis of distal rod  310 , thereby allowing surgeons to penetrate bony surfaces in locations which do not allow coaxial alignment. In such embodiments, the proximal-most surface of penetrating element  210  and retaining element  212  will not be normal to the elements&#39; axis, but rather formed at a predetermined angle such that striking this surface with distal rod  310  produces a penetrating force that is not coaxial with rod  310 . 
         [0118]      FIG. 31  depicts surgical percussive driver device  100  positioned for the microfracture treatment of an articular lesion  602  in bone  600 . In form, lesion  602  has a form resembling that of a pot-hole. In preparation for treatment, the walls of the “pot-hole” have been cleared back to stable articular cartilage and surface  604  has been abraded using a powered device or curette. As seen in  FIG. 32 , the distal end of element  210  is placed in contact with surface  604 . Rotation of hub  320  and cooperative action between element  204  and surface  324  of hub  320  causes compression of the proximal spring such that distal end  314  of element  310  is displaced proximally from element  312  and the proximal end of element  310 . Referring now to  FIGS. 33 and 34 , continued rotation of hub  320  allows inner assembly  300  to travel distally as stored spring energy is converted to kinetic energy. As best seen in  FIG. 34 , distal end  314  of rod  310  impacts the proximal end of element  210  and element  212  thereby percussively transferring energy to element  210  causing penetration of surface  604 . Continued activation of the shaver handpiece causes repeated percussive transfer of energy to element  210  thereby causing continued penetration of element  210  into surface  604  until element  210  has reached a predetermined depth as depicted in  FIGS. 35 and 36  creating conical void  606 . The process is repeated so as to form a plurality of conical voids  606  as depicted in  FIG. 37 . 
         [0119]    Percussive surgical devices of the present invention may be advantageously used for a variety of applications and is thus not limited to the application described above. For instance, in an alternate embodiment  1000  depicted in  FIGS. 38 and 39 , the construction and operation of which are identical to percussive surgical driver device  100  except as described hereafter, distal element  210  with its conically pointed distal portion is replaced by planar elongate distal element  1210  having a sharpened distal edge  1211 . Element  1210  functions as a chisel, the percussive energy transferred to it allowing the sharpened distal end  1211  to remove material from bony surfaces so as create flat surfaces.  FIG. 40  depicts the distal portion of a similar embodiment in which the elongate element  1210  has a curved cross-section and sharpened distal edge  1211  so as to allow device  1000  to create grooves in bony surfaces. 
         [0120]    The use of implants to affix tissue grafts to bone is well known. Common procedures in which such implants (also called “anchors”) are used include the repair of rotator cuff tears, and the repair of torn ligaments in the knee, among others. In these procedures, a socket is drilled or punched in the bone at the attachment site and a graft is secured to the bone using an implant placed in the socket. The graft may be secured to the implant by sutures, or an end of the graft may be placed in the socket and secured directly by an implant. Such implants may be threaded and placed in the socket by torque applied to the anchor. Alternatively, the anchor may be an interference plug-type that is not rotated for insertion, but rather forced into the socket by percussive energy that is conventionally supplied by a mallet applied to the anchor driver proximal end. 
         [0121]    The placement of an interference plug-type anchor in a prepared socket may be advantageously accomplished using a percussive surgical device of the instant invention.  FIGS. 41 through 45  depict device  2000  with interference plug-type anchor  2700  loaded to the distal end thereof in preparation for placement of anchor  2700  in a prepared socket for the purpose of securing a graft. In all aspects of construction and function, device  2000  is identical to device  100  except as subsequently described. As best seen in  FIG. 45 , distal element  2210  has an elongate cannulated distal portion  2211  on which implant  2700  is positioned, and a proximal lateral opening  2209  in communication with the central lumen of distal portion  2211 . Loading loop  2702  is formed from a suitable wire and has formed on its proximal end pull-tab  2704 . By placing sutures in loading loop  2702  and withdrawing the loop proximally using pull tab  2704 , sutures may be loaded into elongate portion  2211  of distal element  2210  such that the distal portion of the sutures extend beyond the distal end of distal element  2210  and implant  2700 , and the proximal portion extends proximally from lateral opening  2209 .  FIGS. 46  through  49  depict device  2000  with sutures  2800  so loaded there to. Distal portions  2802  of sutures  2800  extend distally beyond the distal end of anchor  2700  and distal portion  2211  of distal element  2210 , and proximal portions  2804  extend proximally from lateral opening  2209  of distal element  2210 . 
         [0122]    Illustrative steps for placing anchor  2700  in prepared socket  2902  of bone  2900  to affix graft  2910  are depicted in  FIGS. 50 through 53 . Referring first to  FIG. 50 , sutures  2800  have been passed through graft  2910  in the usual manner, and loaded into device  2000  in the manner previously herein described such that distal portions  2802  of sutures  2800  are secured to graft  2910 , and proximal portions  2804  of sutures  2800  extend proximally from distal element  2210  to outside of the joint space where they may be tensioned by the surgeon. Device  2000  is positioned as depicted in  FIG. 50  such that the distal end of anchor  2700  is adjacent to the top of socket  2902 . In  FIG. 51 , the surgeon has applied tension to proximal portions  2804  of sutures  2800  so as to draw graft  2910  into positioned a predetermined distance from socket  2902 , the distance being determined such that when implant  2700  is placed in socket  2902 , graft  2910  will be in the desired position for fixation. While maintaining tension on sutures  2800  so as to maintain the graft position, the distal end of anchor  2700  is inserted into the socket and, while maintaining slight distal force, the shaver handpiece is activated so as to percussively force implant  2700  into socket  2902 . When graft  2910  is at the desired fixation location and implant  2700  is inserted such that its proximal end is below the proximal end of socket  2902 , the handpiece is deactivated and anchor placement is complete as depicted in  FIG. 52 , suture distal portions  2802  being trapped between anchor  2700  and the wall of socket  2902 .  FIG. 53  depicts the fixation using anchor  2700  with sutures  2800  trimmed just proximal to anchor  2700 . 
         [0123]    Anchor  2700  is of a type known as a “knotless anchor”. When a graft is secured using a knotless anchor, suture are passed through the graft prior to anchor placement and the tying of knots to secure fixation of the graft is not required. Percussive driver device  2000  may also be used for placing anchors in which the sutures are loaded into the anchor before it is placed in the socket, the sutures being subsequently passed through the graft and fixation of the graft achieved through the tying of knots proximal to the anchor and graft. 
         [0124]    In the exemplary fixation of graft  2910  using implant  2700  previously herein described, fixation of sutures  2800  is achieved by trapping the sutures between anchor  2700  and the wall of socket  2902 . In other embodiments, fixation is achieved by trapping a portion of graft  2910  between anchor  2700  and the wall of socket  2902 , a technique known as bio-tenodesis. The placement of anchor  2700  for bio-tenodesis differs from the technique previously herein described in that, instead of leaving a predetermined length of distal suture portions  2802  between the distal end of anchor  2700  and graft  2910 , graft  2910  is drawn to the distal end of anchor  2700  by tension applied to proximal portions  2804  of sutures  2800 . Thereafter, anchor  2700  and a portion of graft  2910  are inserted into socket  2902  in the manner previously herein described. 
         [0125]    Embodiments of the instant invention heretofore described are configured for use with standard shaver handpieces, particularly arthroscopic shavers, wherein the devices of the instant invention convert the rotational motion (and torque) native to the handpiece to axial percussive energy that may be applied to the distal end device component(s). The hubs described herein are standard shaver hubs on which cooperating cam and follower geometries have been formed. The inner assembly is propelled distally by the spring (or other compressible element) that is part of the device assembly. The travel of the inner assembly relative to the outer assembly is limited by the engagement between the inner hub proximal torque transmitting portion and the driving element of the shaver handpiece. The percussive energy transmitted to the distal element of the outer assembly may be increased by increasing the spring constant of the device spring. The maximum percussive energy which may be applied to the distal element is therefore limited by characteristics of the device, i.e. the maximum axial travel of the inner assembly, and the maximum spring constant which the shaver handpiece has sufficient torque to compress. 
         [0126]    The present invention contemplates embodiments that utilize a handpiece for driving the device that is not a standard shaver handpiece but rather a handpiece which provides percussive energy rather than rotational energy and is constructed in accordance with principles of the instant invention. Because percussive energy is supplied to the device by the handpiece rather than by conversion of rotational energy to percussive by the device, the amount of percussive energy supplied to the distal element may be much greater. This, in turn, allows the use of larger distal elements that require higher levels of percussive energy to achieve clinical effects. 
         [0127]      FIGS. 54 through 60  depict such an alternate embodiment device  3000  configured for use with a handpiece that supplies percussive energy to the proximal end of the inner assembly of the device, the handpiece and device  3000  together forming a percussive surgical system constructed in accordance with the principles of the instant invention. Referring to the figures, device  3000  is alike in construction to embodiments previously herein described, except as subsequently described. Distal element  3210  of device  3000  has a distal portion with a square cross-section, a central lumen  3240 , a sharpened distal edge therebetween, and a proximal lumen  3242 . As best seen in  FIG. 60 , inner hub  3302  has no features for torque transmission, being instead configured to provide a means for transmitting proximal spring force from spring  3340  positioned between outer hub  3202  and inner hub  3302  to inner rod element  3310 . Referring to  FIG. 59 , distal element  3210  may move axially within element  3208  distance  3510 . In its unconstrained state, distal end  3314  of inner rod element  3310  is displaced distance  3520  from the proximal end of elements  3210  and  3212 . 
         [0128]    Referring now to  FIGS. 61 through 63 , which depict device  3000  with corresponding elements of a percussive handpiece, thereby forming a system of the instant invention, drive element  3410  of the handpiece is in its retracted position in preparation for release causing drive element  3410  to travel distally at high velocity so as to cause distal end  3314  of inner element  3310  to impact the proximal end of element  3210  and element  3212  thereby impart percussive energy thereto. Proximal force provided by spring  3340  on hub  3302  and therethrough to inner rod member  3310  maintains contact between the proximal end of member  3310  and drive element  3410  of the handpiece. 
         [0129]      FIGS. 64 through 66  depict the elements of  FIGS. 61 through 63  except as depicted in  FIG. 64 through 66  drive element  3410  of the handpiece is at the distal extent of its travel, having imparted percussive energy to rod element  3310  and therethrough to distal element  3210  thereby causing distal element  3210  to travel distally distance  3560 . Thereafter drive element  3410  is retracted proximally in the handpiece, spring  3340  maintaining contact between the proximal end of inner rod element  3310  and the distal end of drive element  3410 . When drive element  3410  has reached its proximal limit of travel, device  3000  and elements of the handpiece are as depicted in  FIGS. 61 through 63 . Cycling of the handpiece and device  3000  mounted thereto as herein described results in the repetitive transfer of percussive energy to distal element  3210  so as to allow penetration of element  3210  into a bony surface, or the driving of an implant into a prepared socket as previously herein described. The cycling frequency is preferably between one and ten Hertz, and more preferably between one and five Hertz. In a preferred embodiment the handpiece cycle rate is controlled by the surgeon by means of a proportional control for activation, the cycle rate at full displacement of the control being the device maximum rate. At slight levels of displacement of the activation control the speed is minimal so as to allow a high level of control of the penetration of the distal element  3210 . 
         [0130]    Distal element  3210  of device  3000  is configured for the forming of square holes in a bony surface, the holes being formed in the following manner. A guide-wire (a small diameter rod) is placed at the desired location. Using a cannulated drill having a diameter equal to lumen  3240  of element  3210 , a hole is drilled to a predetermined depth. Thereafter, device  3000  with is associated percussive handpiece is introduced to the site such that the guidewire enters cannulation  3242  of distal element  3210  thereby aligning element  3210  with the drilled hole. The distal sharpened end of element  3210  is then brought into contact with the bony surface and the handpiece activated so as to percussively drive element into the bone so as to create a square hole for the placement therein of a graft. 
         [0131]    Distal element  3210  is configured to form a square socket by the removal of material. In an alternate embodiment depicted in  FIG. 64 , cannulated distal element  4210  is configured to produce a square socket by dilation of the bone adjacent to the previously drilled round hole. That is, instead of removing bone to create the square profile of the socket, bone is compacted to form the corners, the distal end of element  4210  being rounded so as to compact bone rather than sharpened as in element  3210  for the removal of bone. In all other aspects, the embodiment is identical to device  3000 . 
         [0132]    The ability to form a rectangular or square socket or tunnel is useful for surgeons who use a bone-patellar tendon-bone construct for ACL repair. Currently the graft has trapezoidal bone plugs at its ends when harvested and these bones must be made round to fit into standard round tunnels. Eliminating this rounding step by using square or rectangular tunnels in the repair allows significant savings in procedure time. 
       INDUSTRIAL APPLICABILITY 
       [0133]    As noted previously, the present invention is directed to a surgical assembly having powered driver components that serve to control and automate the application of “percussive force” to the distal end component(s) of the assembly. By automating the percussive force, the present invention not only avoids the present need in the art for a “third hand” but further allows for precisely metered and controlled application of percussive force, thereby minimizing the risk of patient trauma and maximizing device efficiency. Although described in detail with respect to arthroscopic applications, it will be readily apparent to the skilled artisan that the utility of the present invention extends to other minimally invasive endoscopic interventions, particularly with respect to orthopedic procedures such as compound fracture repair and bone grafting. 
         [0134]    The disclosure of each publication, patent or patent application mentioned in this specification is specifically incorporated by reference herein in its entirety. However, nothing herein is to be construed as an admission that the invention is not entitled to antedate such disclosure by virtue of prior invention. 
         [0135]    The invention has been illustrated by reference to specific examples and preferred embodiments. However, it should be understood that the invention is intended not to be limited by the foregoing description, but to be defined by the appended claims and their equivalents.