Patent Publication Number: US-2023145965-A1

Title: Tissue debulking device

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to surgical tools, and related methods, for tissue removal. 
     BACKGROUND 
     Excess body tissue can lead to pathological conditions giving rise to pain, especially when the excess body tissue impinges on a nerve. One such common condition is spinal stenosis: narrowing (stenosis) of the spinal canal, due to excess bone tissue pressing on the spinal cord and resulting in a neurological deficit. Other such common conditions include bulging or herniated discs, which are associated with osteophyte formation in the spinal canal. 
     Standard treatments for spinal stenosis include corpectomy, laminectomy, and osteotomy: surgical procedures involving removing from a vertebra any bone spurs pressing on the spinal cord, and thereby decompressing the spinal cord and nerves and alleviating the neurological deficit. Treatment of a herniated disc typically involves a surgical procedure called discectomy, during which herniated disc material that presses against the nerve root or spinal cord is removed. 
     These surgical procedures, and others, require selective removal of target tissue—which is often difficult to reach—while avoiding damage to surrounding tissue. This task is made doubly difficult when, in addition, the target tissue is hard tissue, such as resulting from excess bone growth on a vertebra. 
     SUMMARY 
     Aspects of the disclosure, according to some embodiments thereof, relate to surgical tools, and related methods, for tissue removal. More specifically, but not exclusively, aspects of the disclosure, according to some embodiments thereof, relate to surgical tools configured for breaking up hard/hardened tissue by hammering/pounding/grounding/grating the tissue. 
     The surgical tools and methods of the present disclosure allow for selective removal of tissue in difficult-to-reach anatomical sites while minimizing damage to surrounding tissue. Advantageously, the surgical tools and methods of the present disclosure make use of the mechanical properties of the tissue, that is to be removed, in order to prevent/mitigate damage to surrounding tissue. According to some embodiments, the surgical tools and methods of the present disclosure are configured for hammering tissue, and, as such, are adapted to debulk hard tissue (such as bone), which is breakable/brittle, while avoiding/mitigating damage to soft tissue (around the bone), which is elastic. More specifically, by virtue of its rigidity, bone poses resistance to hammering by a hard tool, and, as such, is debulked thereby. In contrast, by virtue of its elasticity, soft tissue is not harmed, or substantially not harmed, by hammering by a hard and blunt tool, as the soft tissue moves back and forth with the tool. Advantageously, the inherent safety exhibited by the surgical tools and methods of the present disclosure with respect to soft tissue, may allow to shorten the duration of hard tissue removal procedures, which are performed in close vicinity to neural elements. 
     Thus, according to an aspect of some embodiments, there is provided a surgical tool for debulking hard tissue. The surgical tool includes:
         A hollow member, which is elongated and includes a distally located bent section.   A cable extending within the hollow member, along a predetermined length thereof, from a cable proximal end to a cable distal end. The cable is configured to resist helixing.   A headpiece positioned at, or distally to, the bent section.   A rotation actuator coupled to the cable proximal end and configured to rotate the cable about a longitudinal axis thereof.   A motion converter coupled to the cable distal end and to the headpiece. At least a part of the motion converter is positioned in, and/or distally, to the bent section. The motion converter is configured to transform rotational motion of the cable into an axial, reciprocating motion of the headpiece.       

     The headpiece is configured to break up hard tissue by hammering thereof, when effecting axial, reciprocating motion, while simultaneously minimizing damage to soft tissue if struck. 
     According to some embodiments, the surgical tool is configured to allow the headpiece to strike hard tissue at rate of at least about 10,000 strikes per minute (SPM). 
     According to some embodiments, the motion converter includes a cam, coupled to the cable distal end, and a pushrod mechanically coupled to, or including, the headpiece. The pushrod is configured to engage the cam and to effect axial, reciprocating motion. 
     According to some embodiments, the surgical tool further includes a main section and a distal section. The bent section is joined on a proximal end thereof to the main section and on a distal end thereof to the distal section. The cam is positioned in the distal section. 
     According to some embodiments, at least during a part of the axial, reciprocating motion, the headpiece distally projects from a distal end of the distal section. 
     According to some embodiments, at least a portion of the cable, which extends along the bent section, is flexible. 
     According to some embodiments, the surgical tool further includes a stopper mechanism configured to restrict axial displacement of the pushrod in at least the distal direction. 
     According to some embodiments, the pushrod includes a pinhole extending from one side-surface thereof to an opposite side-surface thereof The stopper mechanism includes a pin extending through the pinhole from one sidewall of the distal section to an opposite sidewall thereof The pinhole may have a diameter greater than the pin, thereby restricting axial displacement of the pushrod while allowing for axial reciprocating motion of the pushrod. 
     According to some embodiments, the surgical tool further includes a linear-motion bearing, positioned at the distal end of the distal section such that the pushrod extends therethrough. The linear-motion bearing is configured to facilitate axial, reciprocating motion of the pushrod. 
     According to some embodiments, the motion converter includes a sleeve element mountable on or insertable into the distal section. The sleeve element includes the pushrod which is at least partially disposed within and along the sleeve element. 
     According to some embodiments, the pushrod includes a pinhole extending from one side-surface thereof to an opposite side-surface thereof The stopper mechanism includes a pin extending through the pinhole from one sidewall of the sleeve element to an opposite sidewall thereof The pinhole may have a diameter greater than the pin, thereby restricting axial displacement of the pushrod while allowing for axial reciprocating motion of the pushrod. 
     According to some embodiments, the cam includes one or more lobes, projecting from a distal end of the cam, such as to engage a proximal end of the pushrod when the cam effects rotary motion. 
     According to some embodiments, a distal end of the cam defines an oblique surface, the cam being thereby configured to engage a proximal end of the pushrod when the cam effects rotary motion. 
     According to some embodiments, the pushrod extends in parallel, or substantially in parallel, to a central axis of the distal section and is displaced relative to the central (longitudinal) axis of the distal section. 
     According to some embodiments, the surgical tool is configured to effect the axial, reciprocating motion of the headpiece at rate of at least about 10,000 SPM when the angle is smaller than 180° and the cable is bent at a bend radius below 10 mm. 
     According to some embodiments, the surgical tool is further configured to operate such that the cable rotates at a rate of at least about 10,000 revolutions per minute (RPM). 
     According to some embodiments, the surgical tool is further configured to effect axial, reciprocating motion such as to allow hammering a rate of up to about 240,000 SPM. 
     According to some embodiments, the cable includes a plurality of braided/intertwined/stranded wires. 
     According to some embodiments, the hard tissue is bone tissue. 
     According to some embodiments, the surgical tool further includes a handle configured to facilitate operation and control of the surgical tool by an operator. 
     According to some embodiments, a distal tip of the headpiece includes an eroding surface, including one or more protrusions, and configured for hammering hard tissue. 
     According to some embodiments, a circumferential surface of the headpiece is eroding, the surgical tool being thereby further configured for debulking hard tissue by grating. 
     According to an aspect of some embodiments, there is provided a surgical tool for debulking hard tissue. The surgical tool includes:
         A hollow member, which is elongated and includes a main section and a distal section. The distal section is positioned at an angle relative to the main section.   A cable, which is elongated and includes a cable proximal end and a cable distal end. The cable extends within the main section there along and is configured to resist helixing.   A work element exposed on a sidewall of the distal section. The work element is configured for transverse, reciprocating motion, wherein, at least during a part of the transverse, reciprocating motion, the work element radially projects from the sidewall.   A rotation actuator coupled to the cable proximal end and configured to rotate the cable about a longitudinal axis thereof.   A motion converter coupled to the cable distal end and to the work element. The motion converter is configured to transform rotational motion of the cable into the transverse, reciprocating motion of the work element.       

     The work element includes a radially facing eroding surface. The work element is configured to break up hard tissue by hammering thereof, when effecting transverse, reciprocating motion, while simultaneously minimizing damage to soft tissue if struck. 
     According to some embodiments, the motion converter includes a rotatable cam and a resilient member. The work element is coupled to the resilient member. The cam includes one or more projections configured to laterally push the work element as the cam revolves. The resilient member is configured to exert a return force on the work element when the work element projects from the sidewall. The work element is thereby configured to effect the transverse, reciprocating motion when the cam revolves. 
     According to some embodiments, the resilient member is a spring. 
     According to some embodiments, the spring is a leaf spring. 
     According to some embodiments, the one or more projections are configured to directly laterally push the work element as the cam revolves. 
     According to an aspect of some embodiments, there is provided a surgical tool for debulking hard tissue. The surgical tool includes:
         An elongated hollow member including a main section and a distal section.   A cable extending within the hollow member along a predetermined length thereof, from a cable proximal end to a cable distal end. The cable is configured to resist helixing.   A headpiece positioned at the distal section.   A rotation actuator coupled to the cable proximal end and configured to rotate the cable about a longitudinal axis thereof.   A motion converter positioned in, or in proximity to, the distal section. The motion converter is coupled to the cable distal end and to the headpiece. The motion converter is configured to transform rotation of the cable into an axial or transverse, reciprocating motion of the headpiece.       

     The headpiece is configured to break up hard tissue by hammering thereof, when effecting axial or transverse, reciprocating motion, while simultaneously minimizing damage to soft tissue if struck. 
     According to some embodiments, the distal section is set at an angle relative to the main section. 
     According to some embodiments, at least a portion of the cable, which extends along a bent section joining the main section to the distal section, is flexible. 
     According to some embodiments, the headpiece is positioned at the distal section of the hollow member, such as to be excentric. 
     According to some embodiments, the surgical tool further includes one or more electrodes positioned on a distal tip of hollow member, such as to render the surgical tool configured for electrophysiological monitoring and/or neurostimulation. 
     According to some embodiments, the surgical tool further includes one or more electrical wires embedded within a wall of the hollow member such that respective distal ends of the one or more wires are connected to the one or more electrodes respectively. 
     According to some embodiments, at least part of the hollow member is made of an electrically conducting material(s) extending along a length of the hollow member until the distal tip thereof The distal tip constitutes the one or more electrodes and is configured to function as a single electrode. The hollow member is thereby configured to allow establishing a voltage between the one or more electrodes and an external electrode placed on/in a body of a subject during a hard tissue debulking procedure. 
     According to some embodiments, at least part of the hollow member is made of an electrically conducting material(s) extending along a length of the hollow member until the distal tip thereof The one or more electrodes include at least two electrodes. The distal tip constitutes the at least two electrodes and is configured to function as two electrodes. 
     The hollow member is thereby configured to allow establishing a voltage difference between the at least two electrodes. 
     According to some embodiments, the surgical tool is configured to allow the headpiece to strike hard tissue at rate of at least about 10,000 strikes per minute (SPM). 
     According to some embodiments, the motion converter includes a cam, coupled to the cable distal end, and a pushrod mechanically coupled to, or including, the headpiece. The pushrod is configured to engage the cam and to effect axial, reciprocating motion. 
     According to some embodiments, at least during a part of the axial, reciprocating motion, the headpiece distally projects from a distal end of the distal section. 
     According to some embodiments, the surgical tool further includes a stopper mechanism configured to restrict axial displacement of the pushrod in at least the distal direction. 
     According to some embodiments, the pushrod includes a pinhole extending from one side-surface thereof to an opposite side-surface thereof The stopper mechanism includes a pin extending through the pinhole from one sidewall of the distal section to an opposite sidewall thereof The pinhole may have a diameter greater than the pin, thereby restricting axial displacement of the pushrod while allowing for axial reciprocating motion of the pushrod. 
     According to some embodiments, the surgical tool further includes a linear-motion bearing, positioned at the distal end of the distal section such that the pushrod extends therethrough. The linear-motion bearing is configured to facilitate axial, reciprocating motion of the pushrod. 
     According to some embodiments, the motion converter includes a sleeve element mountable on or insertable into the distal section. The sleeve element includes the pushrod which is at least partially disposed within and along the sleeve element. 
     According to some embodiments, the pushrod includes a pinhole extending from one side-surface thereof to an opposite side-surface thereof The stopper mechanism includes a pin extending through the pinhole from one sidewall of the sleeve element to an opposite sidewall thereof The pinhole may have a diameter greater than the pin, thereby restricting axial displacement of the pushrod while allowing for axial reciprocating motion of the pushrod. 
     According to some embodiments, the cam includes one or more lobes, projecting from a distal end of the cam, such as to engage a proximal end of the pushrod when the cam effects rotary motion. 
     According to some embodiments, a distal end of the cam defines an oblique surface, the cam being thereby configured to engage a proximal end of the pushrod when the cam effects rotary motion. 
     According to some embodiments, the surgical tool is configured to effect the axial, reciprocating motion of the headpiece at rate of at least about 10,000 SPM when the angle is smaller than 180° and the cable is bent at a bend radius below 10 mm. 
     According to some embodiments, the surgical tool is configured to operate such that the cable rotates at a rate of at least about 10,000 revolutions per minute (RPM). 
     According to some embodiments, the surgical tool is further configured to effect axial, reciprocating motion such as to allow hammering a rate of up to about 240,000 SPM. 
     According to some embodiments, the cable includes a plurality of braided/intertwined/stranded wires. 
     According to some embodiments, the hard tissue is bone tissue. 
     According to some embodiments, the surgical tool further includes a handle configured to facilitate operation and control of the surgical tool by an operator. 
     According to some embodiments, a distal tip of the headpiece includes an eroding surface, is one or more protrusions, and configured for hammering hard tissue. 
     According to some embodiments, a circumferential surface of the headpiece is eroding, the surgical tool being thereby further configured for debulking hard tissue by grating. 
     Certain embodiments of the present disclosure may include some, all, or none of the above advantages. One or more other technical advantages may be readily apparent to those skilled in the art from the figures, descriptions, and claims included herein. Moreover, while specific advantages have been enumerated above, various embodiments may include all, some, or none of the enumerated advantages. 
     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 this disclosure pertains. In case of conflict, the patent specification, including definitions, governs. As used herein, the indefinite articles “a” and “an” mean “at least one” or “one or more” unless the context clearly dictates otherwise. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Some embodiments of the disclosure are described herein with reference to the accompanying figures. The description, together with the figures, makes apparent to a person having ordinary skill in the art how some embodiments may be practiced. The figures are for the purpose of illustrative description and no attempt is made to show structural details of an embodiment in more detail than is necessary for a fundamental understanding of the disclosure. For the sake of clarity, some objects depicted in the figures are not to scale. 
       In the figures: 
         FIG.  1 A  is a schematic, perspective view of a surgical tool configured for hard tissue removal, according to some embodiments; 
         FIG.  1 B  is a schematic, cross-sectional view of the surgical tool of  FIG.  1 A , according to some embodiments; 
         FIG.  1 C  is a schematic, perspective view of a distal portion and a headpiece of the surgical tool of  FIG.  1 A , according to some embodiments; 
         FIG.  1 D  is a schematic, perspective view of a motion converter and the headpiece of the surgical tool of  FIG.  1 A , according to some embodiments; 
         FIG.  1 E  is a schematic, perspective view of a distal portion of a surgical tool configured for hard tissue removal, according to some embodiments; 
         FIG.  1 F  is a schematic, cross-sectional view of a specific embodiment of the surgical tool of  FIG.  1 A ; 
         FIG.  2    is a schematic, cutaway view of a distal portion of a surgical tool for hard tissue removal, according to some embodiments; 
         FIG.  3 A  is a schematic, perspective view of a surgical tool for hard tissue removal, according to some embodiments; and 
         FIG.  3 B  is a schematic, perspective view of a motion converter of the surgical tool of  FIG.  3 A , according to some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The principles, uses, and implementations of the teachings herein may be better understood with reference to the accompanying description and figures. Upon perusal of the description and figures present herein, one skilled in the art will be able to implement the teachings herein without undue effort or experimentation. In the figures, same reference numerals refer to same parts throughout. 
     In the description and claims of the application, the words “include” and “have”, and forms thereof, are not limited to members in a list with which the words may be associated. 
     In the description and claims of the application, the expression “at least one of A and B”, (e.g. wherein A and B are elements, method steps, claim limitations, etc.) is equivalent to “only A, only B, or both A and B”. In particular, the expressions “at least one of A and B”, “at least one of A or B”, “one or more of A and B”, and “one or more of A or B” are interchangeable. 
     As used herein, the term “about” may be used to specify a value of a quantity or parameter (e.g. the length of an element) to within a continuous range of values in the neighborhood of (and including) a given (stated) value. According to some embodiments, “about” may specify the value of a parameter to be between 80% and 120% of the given value. For example, the statement “the length of the element is equal to about 1 m” is equivalent to the statement “the length of the element is between 0.8 m and 1.2 m”. According to some embodiments, “about” may specify the value of a parameter to be between 90% and 110% of the given value. According to some embodiments, “about” may specify the value of a parameter to be between 95% and 105% of the given value. 
     As used herein, according to some embodiments, the terms “substantially” and “about” may be interchangeable. 
     For ease of description, in some of the figures a three-dimensional cartesian coordinate system (with orthogonal axes x, y, and z) is introduced. It is noted that the orientation of the coordinate system relative to a depicted object may vary from one figure to another. 
     Further, the symbol   may be used to represent an axis pointing “out of the page”, while the symbol   may be used to represent an axis pointing “into the page”. 
       FIG.  1 A  schematically depicts a surgical tool  100  for hard/hardened tissue (e.g. bone) removal, according to an aspect of some embodiments. Surgical tool  100  includes a hollow member  102 , which is elongated, and a headpiece  104 . According to some embodiments, hollow member  102  may be tubular (i.e. the lateral cross-section thereof may be circular, cylindrical, square, rectangular, or polygonal) and may include at least one lumen  106  (shown in  FIG.  1 B ) extending distally along a length of hollow member  102  from a proximal end of hollow member  102 . Hollow member  102  includes a main section  112  and a distal section  114  positioned distally relative to main section  112  and at an angle α relative thereto (that is, main section  112  and distal section  114  define the angle α there between). According to some embodiments, distal section  114  is joined to main section  112  or detachably connected thereto. Surgical tool  100  may be configured to allow (distal) projection of headpiece  104  from a distal end  116  (indicated in  FIG.  1 C ) of distal section  114 , and, in particular, a change in the extent of the distal projection (e.g. 
     when headpiece  104  effects axial, reciprocating motion, as described below). According to some embodiments, headpiece  104  is exposed on or (distally) projects from distal end  116 . According to some embodiments, main section  112  and distal section  114  are joined, or detachably coupled, by a bent section  118  (e.g. a curved portion or a portion which is partially folded). 
     According to some embodiments, main section  112  and bent section  118  are not distinct in the sense that a distal end portion of main section  112  and a proximal end portion of bent section  118  are one and the same. Additionally, or alternatively, according to some embodiments, bent section  118  and distal section  114  are not distinct in the sense that a distal end portion of bent section  118  and a proximal end portion of distal section  114  are one and the same. 
     According to some embodiments, wherein (i) the distal portion of main section  112  and the proximal portion of bent section  118  are one and the same, and (ii) the distal portion of bent section  118  and the proximal portion of distal section  114  are one and the same, bent section  118  may be sharply bent. 
     According to some embodiments, and as depicted in  FIG.  1 A , surgical tool  100  further includes a handle  120  configured to facilitate operation and control of surgical tool  100  (e.g. by a surgeon), as elaborated on below. According to some embodiments, and as depicted in  FIG.  1 B , main section  112  may extend into handle  120 . 
     According to some embodiments, the diameter of hollow member  102  is between about 2 mm and about 10 mm. According to some embodiments, wherein the diameter of hollow member  102  varies along the length thereof, the minimum diameter is greater than about 2 mm and the maximum diameter is smaller than about 10 mm. According to some embodiments, the diameter of hollow member  102 , or the maximum diameter thereof, is about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, or about 10 mm. Each possibility corresponds to separate embodiments. According to some embodiments, the length of hollow member  102  is between about 100 mm and about 500 mm. According to some embodiments, the length of hollow member  102  is between about 150 mm and about 250 mm. According to some embodiments, the length of hollow member  102  is about 100 mm, about 150 mm, about 200 mm, about 250 mm, about 300 mm, or about 420 mm. Each possibility corresponds to separate embodiments. 
     According to some embodiments, the angle a between main section  112  and distal section  114  may be between about 90° and about 120°, about 130°, about 135° about 140°, about 150°, about 160°, about 165°, about 170°, or about 180°. Each possibility corresponds to separate embodiments. According to some embodiments, hollow member  102 , and, in particular, bent section  118 , are characterized by a bend radius of about 25 mm, about 18 mm, about 15 mm, about 12 mm, about 9 mm, about 7 mm, or even about 5 mm. Each possibility corresponds to separate embodiments. According to some embodiments, the bend radius may be between about 2 mm and about 4 mm. 
     According to some embodiments, the dimensions and shape of surgical tool  100 —particularly, the dimensions and shapes of hollow member  102  and headpiece  104 —are such as to facilitate a “low profile”, safe insertion of headpiece  104 /distal section  114  in between two adjacent vertebrae and allow access to osteophytes located underneath a vertebra. Specifically, the length and diameter of distal section  114 , and the angle a between main section  112  and distal section  114  (e.g. the amount of curving of bent section  118 ) are such as to facilitate a low profile, safe insertion of headpiece  104 /distal section  114 . Further, according to some embodiments, and as depicted in  FIG.  1 D , headpiece  104  is excentric, in the sense of being offset relative to a central (also referred to as “longitudinal”) axis A (indicated in  FIG.  1 C ) of lumen  106 . According to some embodiments, the offsetting may facilitate safe insertion of headpiece  104 . 
     Referring also to  FIG.  1 B ,  FIG.  1 B  is a cross-sectional view of surgical tool  100 , according to some embodiments. The cross-section lies on a plane parallel to the yz-plane. According to some embodiments, surgical tool  100  further includes a cable  130 , which is elongated, a rotation actuator  132 , and a motion converter  134 . Cable  130  may be disposed within (or at least partially disposed within), and along, hollow member  102 , e.g. along lumen  106 . According to some embodiments, rotation actuator  132  is housed within, or at least partially housed within, handle  120 . Motion converter  134  may be housed within distal section  114  and bent section  118 , and, optionally, hollow member  102  (i.e. such that one or more parts thereof are housed in distal section  114  and one or more other parts thereof are housed in bent section  118 , and, optionally, main section  112 ). Cable  130  extends from a cable proximal end  136  to a cable distal end  138 . Cable proximal end  136  is mechanically coupled to, or connected to, rotation actuator  132 . Cable distal end  138  is mechanically coupled to, or connected to, motion converter  134 , which is further mechanically coupled to, or connected to, headpiece  104 . 
     Rotation actuator  132  is configured to induce rotations (i.e. revolutions) of cable  130  about a longitudinal axis of cable  130 . According to some embodiments, wherein cable  130  is centralized within lumen  106 , the longitudinal axis of cable  130  and the central axis A coincide. The central axis A may lie on the plane of the cross-section of  FIG.  1 B , in parallel to the yz-plane. It will be understood that the central axis A may be curved/bent, i.e. when lumen  106  is curved/bent. According to some embodiments, a central axis of hollow member  102  coincides with the central axis A. 
     Motion converter  134  (indicated in  FIG.  1 C ) is configured to translate cable  130  rotation to headpiece  104  reciprocating motion. According to some embodiments, and as depicted in  FIGS.  1 A- 1 D , headpiece  104  reciprocating motion is axial, so that the extent of headpiece  104  projection from distal end  116  may alternately (i.e. by turns) increase and decrease. 
     According to some embodiments, rotation actuator  132  may be an electrical motor. According to some such embodiments, handle  120  may include an electrical port  140 , which is electrically coupled to rotation actuator  132 , thereby allowing to power rotation actuator  132  using an electrical power source external to surgical tool  100 , and, in particular, handle  120 . More generally, rotation actuator  132  may include any combination of mechanical components configured to tightly grip cable  130  (e.g. at, or near, cable proximal end  136 ), such as to allow high-frequency rotation of cable  130  about the longitudinal axis thereof. 
     Referring also to  FIGS.  1 C and  1 D ,  FIG.  1 C  depicts motion converter  134  disposed within hollow member  102 , and  FIG.  1 D  is a perspective view of motion converter  134  and headpiece  104 , according to some embodiments. More specifically, in  FIG.  1 C , the walls of hollow member  102  are depicted as semi-transparent to facilitate the description (so that components within hollow member  102 , such as motion convertor  134 , are visible). Motion converter  134  includes a cam  142  and a pushrod  144  (i.e. a cam follower/tracker) associated with cam  142 . According to some embodiments, and as depicted in the figures, cam  142  may be mounted on/joined to cable distal end  138 . Cam  142  includes one or more lobes  146  (for example, two lobes, as depicted in  FIGS.  1 C and  1 D ), or a tilted plane, configured to engage the proximal end (not numbered) of pushrod  144 . Pushrod  144  is disposed in parallel, or substantially in parallel, to the central axis A and may be displaced (shifted) relative thereto, such as to allow/facilitate engagement of the proximal end of pushrod  144  by lobes  146 , when cam  142  effects rotatory motion about the central axis A. 
     According to some embodiments, pushrod  144  includes headpiece  104 . That is, a distal portion of pushrod  144  is constituted by headpiece  104 . According to some alternative embodiments (not depicted in  FIGS.  1 A- 1 D ), pushrod  144  is mechanically associated with headpiece  104  such that axial, reciprocating motion of pushrod  144  induces an axial, reciprocating motion of headpiece  104 . 
     According to some embodiments, not depicted in  FIGS.  1 A- 1 D , instead of including lobes  146 , the distal end (not numbered) of cam  142  may be oblique (essentially as depicted in  FIG.  2   ). That is, in such embodiments the distal end of cam  142  defines a slanting surface (in the sense of not being perpendicular to the central axis A), which engages the proximal end of pushrod  144  (which may be displaced relative to the central axis A as described above) when cam  142  effects rotary motion about the central axis A. 
     Axial displacement/motion of pushrod  144  may be restricted by a stopper mechanism. More specifically, according to some embodiments, pushrod  144  includes a pinhole  148  extending from one side-surface (not numbered) of pushrod  144  to an opposite side-surface (not numbered) thereof, e.g. perpendicularly, or substantially perpendicularly, to the central axis A. A pin  152  extends through pinhole  148  and is connected on the ends thereof to opposite sidewalls (not numbered) of distal section  114 . Pinhole  148  is of a greater diameter than pin  152 . The greater diameter of pinhole  148  allows for (limited) axial motion of pushrod  144 . However, the motion of pushrod  144 , particularly in the axial direction, is restricted by pin  152 , which effectively functions as a stopper preventing axial displacement of pushrod  144 , and consequently of headpiece  104 , beyond a preset/fixed extent. 
     According to some embodiments, a distal portion (including cable distal end  138 ) of cable  130  is rigid, such as to facilitate the mounting of cam  142  on cable distal end  138 . According to some such embodiments, cable  130  includes a tube element  154 , into which a flexible portion of cable  130  extends and is attached thereto (such that rotations of the flexible portion induce same and simultaneous rotations of the tube). Cam  142  may be configured to be mounted on tube element  154 . 
     According to some embodiments, distal section  114  includes a (linear-motion) bearing  156  positioned at distal end  116 . Pushrod  144 , and, more precisely, a distal portion thereof (not numbered), may be disposed through bearing  156 , which is configured to facilitate pushrod  144  axial reciprocating motion. (According to some embodiments, headpiece  104  may be positioned distally relative to bearing  156 , at least during part of the time when headpiece  104  effects reciprocating motion.) 
     In operation, when cam  142  effects rotary motion, each of lobes  146 , upon striking pushrod  144 , distally pushes pushrod  144  until a pinhole proximal wall  158  (i.e. the proximal wall of pinhole  148 ) strikes (hits) pin  152 . The impact of the strike reverses the direction of motion of pushrod  144 , propelling (sending) pushrod  144  in the proximal direction (at least when the RPM is 4,000 or greater). Pushrod  144  may then be struck again by a lobe (of lobes  146 ), and the motion is then repeated, so that pushrod  144 , and consequently headpiece  104 , effect axial, reciprocating motion. 
     According to some alternative embodiments, pin  152  may be elastic so that when pressed by pushrod  144 —due to the elasticity of pin  152 —pin  152  pushes back pushrod  144 , reversing the direction of motion thereof (and of headpiece  104 ). In such embodiments, pinhole  148  need not have a larger, or substantially larger, diameter than the diameter of pin  152 . Alternatively, pushrod  144  may include or constitute a resilient member (e.g. a spring) mechanically associated with headpiece  104 . The resilient member may be configured to induce and control headpiece  104  reciprocating motion. 
     According to some embodiments, headpiece  104  is configured for breaking up/fragmenting hard/rigid (i.e. non-elastic) tissue by striking/hitting/hammering/grinding the tissue. In particular, a distal tip  162  of headpiece  104  may be configured for hammering hard tissue. Distal tip  162  may be rounded, as depicted in  FIG.  1 C , or flat or substantially flat (e.g. including a flat or even a concave surface perpendicular to a longitudinal axis of distal section  114 ). According to some non-limiting embodiments, and as depicted in  FIG.  1 C , distal tip  162  may include an eroding surface  164  configured for breaking up hard tissue. Eroding surface  164  may include protrusions  166  (shown in  FIG.  1 C ; not all of which are numbered) configured to facilitate the breaking up of hard tissue. Protrusions  166  may be formed, for example, by diamonds embedded in eroding surface  164 . 
     According to some embodiments, eroding surface  164  may be curved, e.g. in the form of a cap. A circumferential surface  170  of headpiece  104  (indicated in  FIG.  1 D ) is positioned proximally to eroding surface  164 . According to some embodiments, circumferential surface  170  may be configured for reciprocating motion in-and-out of bearing  156  during surgical tool  100  operation. 
     According to some embodiments, lumen  106  may follow the curvature of hollow member  102  and may have a diameter between about 30% and about 100% greater than the diameter of cable  130 , thereby ensuring that cable  130  (particularly, the flexible portion(s) thereof, described below) does not kink or warp within lumen  106 . According to some such embodiments, the diameter of lumen  106  is, for example, between about 1 mm and about 4 mm (e.g. 2.8 mm). Lumen  106  may optionally be centered within hollow member  102  (i.e. such that the longitudinal axes thereof overlap). 
     Cable  130  may include a rigid portion (e.g. tube element  154 ) and a flexible portion (not numbered). The rigid portion may be connected to the flexible portion (e.g. via crimping or welding). The rigid portion may extend along a straight segment of lumen  106  (e.g. in main section  112 ), while the flexible portion may extend along bent section  118 , and, optionally, along one or more straight segments of lumen  106 . As elaborated on below, cable  130  may include a rigid tube crimped over an end thereof. 
     According to some embodiments, cable  130  may be configured for high torsional rigidity and low bending rigidity, such as to allow cable  130  to be rotated about the longitudinal axis thereof at high rotation frequencies while bent at a small radius of curvature. In particular, surgical tool  100  is configured to enable the transfer of torque (from rotation actuator  132  to cam  142 ) when cable  130  is bent. Advantageously, this allows for effecting high frequency axial, reciprocating motion of headpiece  104  against hard tissue located at difficult-to-reach anatomical sites (e.g. between vertebrae), which require surgical tool  100  to be bent (in order to reach the anatomical site). High torsional rigidity and low bending rigidity facilitate rotary motion of a wire/cable when bent/curved. Having a low bending rigidity (bending stiffness) potentially allows for low bending-related stress and higher resistance to fatigue which may result from high rotation frequencies and/or high torques. 
     According to some embodiments, cable  130  includes a core including a plurality of intertwined wires configured for maintaining structural integrity and low bending stress. Cable  130  further includes one or more outer layers, configured for transferring torque. According to some embodiments, the plurality of intertwined wires of the core may be braided, stranded and/or twisted. (In particular, according to some embodiments, the core does not consist of a single solid core (e.g. an elongated shaft, a mandrel). The outer layers may be coiled, winded, or twisted, with adjacent layers being coiled/winded in opposite senses—cable  130  being thereby adapted to transfer torque in both senses (e.g. “right-handed” torque and “left-handed” torque). According to some embodiments, at least some adjacent layers (of the outer layers) may be winded in the same sense. 
     According to some exemplary embodiments, the core of cable  130  may be fabricated, for example, from seven 304V stainless-steel wires (each having a diameter of, for example, between about 0.07 mm and about 0.1 mm, e.g. 0.084 mm) twisted and/or intertwined into a rope. More generally, the core of cable  130  may be fabricated, for example, from wires of any of the  300  stainless series and/or Nitinol. Several layers of coils, e.g. three layers, may be wound around the core. Each successive coil may optionally be wound in an opposite direction to (the winding of) the coil directly beneath it. The inner coil (closest to cable&#39;s inner core) may include, for example, five wires (with a diameter of e.g. about 0.12 mm each), the middle coil may include, for example, five wires (with a diameter of e.g. about 0.14 mm each), and the outer coil may include, for example, five wires (with a diameter of e.g. about 0.16 mm each). 
     Cable  130  design is configured to enable the transfer of rotational and longitudinal motion, i.e. torque and rotational frequency and axial force and speed, along curved paths, including highly curved paths, in a manner resistant to fatigue. Such paths may be fixed, as in embodiments wherein bent section  118  is rigid, or variable, as in embodiments wherein bent section  118  is flexible and may conform to a range of angles or curvatures before and/or during the surgery. 
     According to some embodiments, cable  130  has a diameter between about 0.3 mm and about 5 mm, e.g. about 0.5 mm, about 1.5 mm, or about 3 mm. 
     According to some embodiments, cable  130  may be configured to allow rotation frequencies of up to about 120,000 RPM (about the longitudinal axis thereof) and to be acted on by, and to apply, torques of at least about 5 N·cm (newton-centimeter). According to some embodiments, cable  130  may be configured to allow rotation frequencies of up to about 120,000 RPM for both clockwise and anti-clockwise rotations about the longitudinal axis thereof. According to some embodiments, cable  130  may be configured to be acted on by, and to apply, torques of about 5 N·cm or about 7 N·cm. 
     According to some embodiments, to facilitate operation of surgical tool  100 , handle  120  may be shaped substantially as an inverted cone. According to some embodiments, the handle may have a length, for example, between about 50 mm and about 105 mm, a proximal diameter, for example, between about 10 mm and about 30 mm, and a distal diameter, for example, between about 5 mm and about 30 mm. Handle  120  may be fabricated as a shell composed of one or more cast, machined, or injection-molded pieces. 
     According to some embodiments, handle  120  includes an operational input  172  (also referred to as a suction, irrigation and/or working channel). According to some embodiments, operational input  172  may be fluidly coupled to lumen  106  via a channel (not shown), thereby allowing, for example, to irrigate a target tissue site in order to cool or wash the target tissue site. According to some embodiments, operational input  172  may function as a port for introducing/withdrawing/suction of fluids. In particular, operational input  172  may be configured to be coupled to a vacuum pump (e.g. by having inserted thereinto a suction tip). 
     According to some embodiments, a wall of hollow member  102  may have embedded therein a second lumen (not shown) extending along main section  112  from a distal tip of hollow member  102  onto handle  120 . The second lumen may be fluidly coupled to operational input  172  via a channel (not shown) in handle  120 . In such embodiments, operational input  172  may additionally or alternatively be used to introduce additional surgical instruments (e.g. a tissue dissector, a spatula, an electrophysiological monitoring device/neuro-stimulation device, sensors/cameras, and/or the like). 
     According to some embodiments, a distal tip of hollow member  102  may include or form an electrode. For example, distal end  116  may include or form an electrode. According to some embodiments, an electrical wire (not shown) may be embedded within the wall of hollow member  102 , such that a distal end of the wire is connected to the electrode and a proximal end of the wire is configured to be coupled to an electrical power source (e.g. via electrical port  140  or operational input  172 ). The electrode may be used in conjunction with a second electrode placed on the body of a subject (during a surgical procedure wherein surgical tool  100  is inserted into the body of the subject) to provide neuro-stimulation at or near a target tissue site. According to some embodiments, wherein at a least part of hollow member  102  is made of an electrically conducting material (e.g. stainless steel), hollow member  102  may be used to establish a voltage difference between the electrode and the second electrode (so that the necessity of using an electrical wire at least along hollow member  102  is obviated). 
     According to some embodiments, a distal tip of hollow member  102  may include or form two electrodes. For example, distal end  116  may include or form two electrodes. According to some embodiments, electrical wires (not shown) may be embedded within the wall of hollow member  102 , such that distal ends of the wires are connected to the two electrodes, respectively, and proximal ends of the wires are configured to be coupled to an electrical power source (e.g. via electrical port  140  or operational input  172 ). The electrodes may be used to establish a voltage difference there between, such as to allow for localized neuro-stimulation within the body of a subject (during a surgical procedure) at or near a treatment site. According to some embodiments, wherein at least a part(s) of hollow member  102  is made of an electrically conducting material (e.g. stainless steel), hollow member  102  may be used to establish the voltage difference between the two electrodes. 
     According to some embodiments, handle  120  may include a user interface for operating rotation actuator  132 , setting rotation actuator  132  motor parameters (e.g. RPM and sense of rotation), setting the debulking time, operating and setting irrigation parameters, as well as controlling adjunct devices such as a neuro-stimulation device. The user interface may also include a display for presenting various parameters related to rotation actuator  132  operation or to irrigation, as well as information indicative of headpiece  104  and bent section  118  status and condition, such as temperature thereof, mechanical integrity thereof, headpiece  104  position, and the like. According to some embodiments, the user interface may also be configured to display information related to one or more adjunct devices (e.g. an electrophysiological monitoring device) used during a debulking procedure. 
     Furthermore, handle  120  may be designed and configured such that a surgeon is able to maintain a clear line-of-site along surgical tool  100  (and, in particular, hollow member  102 ), so as to allow the surgeon to monitor progress while debulking target tissue and to avoid damaging surrounding tissue (which is not intended for removal). 
       FIG.  1 E  schematically depicts a distal portion of a surgical tool  100 ′, according to some embodiments. Surgical tool  100 ′ includes a hollow member  102 ′, which may be similar to hollow member  102 , and a headpiece  104 ′ configured for breaking up hard tissue by the grating (e.g. filing, polishing) thereof (in addition to, or alternatively to, breaking up the tissue by the hammering/grounding thereof), as explained below. According to some embodiments, wherein headpiece  104 ′ may be utilized both for grating tissue and hammering tissue, surgical tool  100 ′ may be a specific embodiment of surgical tool  100 . 
     To facilitate the description, in  FIG.  1 E  the walls of hollow member  102 ′ are depicted as semi-transparent, so that components within hollow member  102 , such as a motion convertor  134 ′ (which may be similar to motion converter  134 ), are visible. According to some embodiments, and as depicted in  FIG.  1 E , a circumferential surface  170 ′ (e.g. a cylindrical surface) of headpiece  104 ′ is eroding (e.g. rough-textured at least on a distal portion thereof), being thereby configured for grating/fragmenting hard tissue. More specifically, in these embodiments, by bringing surgical tool  100 ′ against a hard tissue surface such that circumferential surface  170 ′ is adjacent to the tissue surface and is in contact therewith, and activating surgical tool  100 ′, due to headpiece  104 ′ axial, reciprocating motion, circumferential surface  170 ′ grates the tissue surface (by moving back and forth in the axial direction), leading to fragmentation of the tissue. 
     Also indicated are a cam  142 ′ and a pushrod  144 ′, which is configured to function as a cam follower/tracker. According to some embodiments, and as depicted in  FIG.  1 E , cam  142 ′ may include lobes  146 ′. According to some alternative embodiments, not depicted in  FIG.  1 E , a distal surface of cam  142 ′ may be oblique. According to some embodiments, and as depicted in  FIG.  1 E , pushrod  144 ′ includes headpiece  104 ′. Alternatively, pushrod  144 ′ may be mechanically associated with headpiece  104 ′ such that axial, reciprocating motion of pushrod  144 ′ induces an axial, reciprocating motion of headpiece  104 ′. Surgical tool  100 ′ is configured such that rotary motion of cam  142 ′ is translated into axial, reciprocating motion of pushrod  144 ′ (and headpiece  104 ′), essentially as described above with respect to surgical tool  100 . 
     According to some embodiments, surgical tool  100 ′ is a specific embodiment of surgical tool  100 , and is configured for breaking up tissue both by hammering and by grating. In such embodiments, both a distal tip  162 ′ of headpiece  104 ′ and circumferential surface  170 ′ are eroding (e.g. rough-textured, with distal tip  162 ′ optionally including protrusions (not shown in  FIG.  1 E ) such as protrusions  166 ).Further indicated in  FIG.  1 E  are a lumen  106 ′, a distal section  114 ′, and a pin  152 ′ (which may be respectively similar to lumen  106 , distal section  114 , and pin  152  of a surgical tool  100 ), and a central axis A′ of lumen  106 ′. 
       FIG.  1 F  is a cross-sectional view of a surgical tool  100 ″, according to some embodiments. Surgical tool  100 ″ constitutes a specific embodiment of surgical tool  100 . Surgical tool  100 ″ includes a pair of lumens, as described below. More specifically, surgical tool  100 ″ includes a hollow member  102 ″, a headpiece  104 ″, and a handle  120 ″, which are specific embodiments of hollow member  102 , headpiece  104 , and handle  120 , respectively. Hollow member  102 ″ includes an inner lumen  106 ″ (which is a specific embodiment of lumen  106 ) and an outer lumen  174 ″ disposed about inner lumen  106 ″, as described below. Inner lumen  106 ″ is defined by an inner wall  176 ″ (e.g. a cylindrical wall), and outer lumen  174 ″ is defined by an outer wall  178 ″ (e.g. a cylindrical wall having a greater radius than inner wall  176 ″) disposed about inner wall  176 ″. Inner lumen  106 ″ includes a cable  130 ″ disposed therein and extending there along. Cable  130 ″ extends from a cable proximal end  136 ″ to a cable distal end  138 ″ and constitutes a specific embodiment of cable  130 . Outer lumen  174 ″ may be fluidly-coupled to an operational input  172 ″ (which is a specific embodiment of operational input  172 ) via a channel  182 ″ in handle  120 ″, thereby allowing introduction and/or withdrawal/suction of fluids via operational input  172 ″, as well as introduction of additional surgical instruments, essentially as described above in the description of surgical tool  100 . 
     Also indicated are a main section  112 ″, a distal section  114 ″, and a bent section  118 ″ of hollow member  102 ″, and a rotation actuator  132 ″, which are specific embodiments of main section  112 , distal section  114 , bent section  118 , and rotation actuator  132 , respectively. 
     According to some embodiments, a distal tip (not indicated) of outer wall  178 ″ may form a first electrode while a distal tip (not indicated) of inner wall  176 ″ may form a second electrode, such as to allow for in vivo neuro-stimulation (and neuro-monitoring) during a surgical procedure wherein bone tissue is removed from a site including one or more nerves. According to some embodiments, each of the walls may include, embedded therein, an electrical wire (not shown) connected on a distal end thereof to the respective electrode and electrically coupled on a proximal end thereof to an electrical port  140 ″ (which is a specific embodiment of electrical port  140 ) or operational input  172 ″, such as to allow establishing a voltage between the electrodes. According to some embodiments, each of outer wall  178 ″ and inner wall  176 ″ may be made of an electrically conducting material, thereby obviating usage of electrical wires embedded within the walls. 
       FIG.  2    schematically depicts a surgical tool  200  (not fully shown) for hard tissue removal, according to some embodiments. Surgical tool  200  includes a hollow member  202  (not fully shown) and a headpiece  204  similar to hollow member  102  and headpiece  104 , respectively. Hollow member  202  includes a main section  212  (not fully shown) and a distal section  214 , which is distally positioned relative to main section  212  at an angle β relative thereto, and joined thereto (e.g. via a bent section  218  of hollow member  202 ). According to some embodiments, β may be between about 90° and about 120°, about 130°, about 135°, about 140°, about 150°, about 160°, about 165°, about 170°, or about 180°. Each possibility corresponds to separate embodiments. 
     According to some embodiments, main section  212  and bent section  218  are not distinct in the sense that a distal end portion of main section  212  and a proximal end portion of bent section  218  are one and the same. Additionally, or alternatively, according to some embodiments, bent section  218  and distal section  214  are not distinct in the sense that a distal end portion of bent section  218  and a proximal end portion of distal section  214  are one and the same. 
     According to some embodiments, wherein (i) the distal portion of main section  212  and the proximal portion of bent section  218  are one and the same, and (ii) the distal portion of bent section  218  and the proximal portion of distal section  214  are one and the same, bent section  218  may be sharply bent. 
     Surgical tool  200  further includes a cable  230  similar to cable  130 , a rotation actuator (not shown) similar to rotation actuator  132 , and a motion converter  234 . Cable  230  and the rotation actuator may be mechanically coupled essentially as described above with respect to cable  130  and rotation actuator  132 . Motion converter  234  may be installable in and/or on distal section  214 . More specifically, motion converter  234  includes a cam  242 , a pushrod  244  (i.e. a cam follower/tracker), and a sleeve element  280 , which may be tubular, having a circular or oval transverse cross-section, or have or rectangular or polygonal transverse cross-section. Sleeve element  280  includes pushrod  244 , which is disposed along the length of sleeve element  280  (in parallel to a central axis B of distal section  214 , which may also be shared by sleeve element  280 ). Cam  242  may be positioned within distal section  214  and may be installable/mountable on a cable distal end  238  (i.e. the distal end of cable  230 ), such that rotation of cable  230  induces (an equal or substantially equal) rotation of cam  242 . 
     According to some embodiments, sleeve element  280  may be installable/mountable on/in distal section  214 , such as to be concentrically disposed thereon/therein, and such as to allow pushrod  244  to be engaged by cam  242 , as elaborated on below. According to some such embodiments, sleeve element  280  may be slid on distal section  214  (and thereby coupled thereto). According to some embodiments, and as depicted in  FIG.  2   , sleeve element  280  is of a slightly greater diameter than distal section  214 , and as such is configured to be mounted on distal section  214 . According to some such embodiments, sleeve element  280  is of a slightly smaller diameter than distal section  214 , and as such is configured to be partially inserted into distal section  214 . 
     According to some alternative embodiments, sleeve element  280  may be non-removably affixed to on distal section  214  or may be integrally formed therewith. 
     Similarly to pushrod  144 , pushrod  244  may include a pinhole  248  extending from one side-surface of pushrod  244  to an opposite side-surface thereof, e.g. perpendicularly, or substantially perpendicularly, to the central axis B. A pin (not shown) extends through pinhole  248  and is connected on the ends thereof to opposite sidewalls (not numbered) of sleeve element  280 . Pinhole  248  may be of a greater diameter than the pin, such as to allow for (limited) axial motion of pushrod  244 , essentially as described above with respect to motion converter  134  and as explained below. 
     According to some embodiments, and as depicted in  FIG.  2   , a cam distal end  284  (i.e. the distal end of cam  242 ) may be oblique (i.e. defining a slanting surface) in the sense of not being perpendicular to longitudinal axis B. Pushrod  244  may be displaced relative to the central axis B (e.g. in parallel, or substantially in parallel, thereto), such that by starting at a configuration, wherein pushrod  244  is proximally positioned to the maximum (so that a distal wall of pinhole  248  may contact a distal wall of the pin), cam distal end  284  strikes pushrod  244  as cam  242  is rotated (about the central axis B). When so struck, pushrod  244  is sent in the distal direction until a proximal wall (not numbered) of pinhole  248  hits the pin, which sends pushrod  244  back in the proximal direction to be struck again by cam  242 , and so on and so forth, such that axial, reciprocating motion of pushrod  244  and, hence, headpiece  204 , is generated. 
     According to some embodiments, cable  230  includes a tube element  254  (which includes cable distal end  238 ) into which a flexible portion of cable  230  extends and is attached thereto (such that rotations of the flexible portion induce same and simultaneous rotations of the tube). Cam  242  may be configured to be mounted on tube element  254 . 
     According to some embodiments, not depicted in  FIG.  2   , cam distal end  284  may include one or more lobes (similar to lobes  146 ) configured to engage pushrod  244 . According to some such embodiments, cam distal end  284  is not oblique. 
     According to some embodiments, a distal tip  262  of headpiece  204  is configured for axial hammering of hard tissue, essentially as described above in the description of headpiece  104  of surgical tool  100 . More specifically, according to some such embodiments, distal tip  262  may include an eroding surface, which may include protrusions similar to protrusions  166  of distal tip  162 . 
     Additionally, or alternatively, according to some embodiments, a circumferential surface (not numbered) of headpiece  204  may be eroding (e.g. rough-textured at least on distal portions thereof), essentially as described above with respect to circumferential surface  170 ′ of headpiece  104 ′ of surgical tool  100 ′. In such embodiments, in addition to, or alternatively to, breaking up hard tissue by (axial) hammering thereof, headpiece  204  (and, hence, surgical tool  200 ) is configured for fragmenting hard tissue by grating (when effecting axial, reciprocating motion adjacently to a surface of the hard tissue, as described above in the description of surgical tool  100 ). 
     According to some embodiments, headpiece  204  is detachably mounted on pushrod  244 , such as to allow replacing headpiece  204 , e.g. due to wear and tear, or in order to mount a different headpiece, of e.g. a different size, shape, and/or roughness of the eroding surfaces. 
     According to some alternative embodiments, headpiece  204  may form a part of pushrod  244  (for example, headpiece  204  and pushrod  244  may be integrally formed). According to some such embodiments, wherein sleeve element  280  is removable, headpiece  204  may be replaced by replacing sleeve element  280 . 
     According to some embodiments, sleeve element  280  includes a first bearing  256  (e.g. a linear-motion bearing) and a second bearing  286  (e.g. a roller bearing). First bearing  256  may be positioned at a distal end (not numbered) of sleeve element  280 . Pushrod  244 , and, more precisely, a distal portion thereof (not numbered), may be disposed through first bearing  256 , which is configured facilitate pushrod  244  axial, reciprocating motion. According to some embodiments, headpiece  204  may be positioned distally relative to first bearing  256 , at least during part of the time when headpiece  204  effects reciprocating motion. Second bearing  286  may be positioned at a proximal end (not numbered) of distal section  214 . Tube element  254  may be disposed through second bearing  286 , which is configured to facilitate tube element  254  rotary motion (and, hence, the imparting of rotation from cable  230  to cam  242 ). 
     According to some embodiments, motion converter  234  is detachably mountable. That is, each of sleeve element  280  and cam  242  may be removed and replaced, thereby allowing to mount on distal section  214  a debulking element with a different function, such as a drill bit or a cutting bit, so as to allow using surgical tool  200  (omitting headpiece  204 , motion converter  234 , and sleeve element  280 , but with a debulking element installed on distal section  214 ) also for e.g. drilling and/or cutting, and, in particular, for debulking soft (elastic) tissue. According to some such embodiments, surgical tool  200  may be provided as part of a kit including (in addition to headpiece  204 , motion converter  234 , and sleeve element  280 ) one or more debulking elements as described above. 
     According to some embodiments, and as depicted in  FIG.  2   , headpiece  204  is excentric, thereby potentially facilitating safe insertion of headpiece  204 . 
       FIG.  3 A  schematically depicts a surgical tool  300  (of which only a distal portion is shown) for hard tissue removal, according to an aspect of some embodiments. Surgical tool  300  is similar to surgical tools  100  and  200  but differs therefrom at least in being configured for transverse (perpendicular to the axial direction) hammering/pounding of hard tissue, instead of axial hammering/pounding of hard tissue, as explained below. Surgical tool  300  includes a hollow member  302  (not fully shown), which may be similar to hollow member  102 , and a work element  304  (e.g. a plate or plate-like element configured for hammering hard tissue). Hollow member  302  includes a main section  312  (not fully shown) and a distal section  314 , which is distally positioned relative to main section  312 , set at an angle y relative thereto, and joined thereto. According to some embodiments, y may be between about 90° and about 120°, about 130°, about 135°, about 140°, about 150°, about 160°, about 165°, about 170°, or about 180°. Each possibility corresponds to separate embodiments. 
     Work element  304  may form or define an eroding surface  364  configured for breaking up hard tissue by striking/repeatedly striking the tissue. According to some embodiments, and as depicted in  FIG.  3 A , eroding surface  364  may include protrusions  366  configured to facilitate the breaking up of the tissue. Protrusions  366  (not all of which are numbered) may be formed, for example, by diamonds embedded in eroding surface  364 . According to some embodiments, apart from protrusions  366 , work element  304 , or at least eroding surface  364 , is flat or substantially flat. According to some other embodiments, work element  304 , or at least eroding surface  364  is curved (e.g. such that, except for protrusions  366 , eroding surface  364  conforms to the cylindrical shape of distal section  314  when work element  304  is tucked in). Surgical tool  300  may be configured to allow transverse projection of work element  304  from a sidewall  388  of distal section  314 , and, in particular, a change in the extent of the transverse projection (e.g. when work element  304  effects transverse, reciprocating motion, as described below). 
     Referring also to  FIG.  3 B ,  FIG.  3 B  provides a perspective view of a motion converter  334  of surgical tool  300 . Work element  304  is also shown and a cable  330  of surgical tool  300  is shown in part. Cable  330  is similar to cable  130 . Surgical tool  300  further includes a rotation actuator (not shown), which may be similar to rotation actuator  132 , and is configured to induce cable  330  rotary motion. In particular, cable  330  and the rotation actuator may be mechanically coupled essentially as described above with respect to cable  130  and rotation actuator  132 . Motion converter  334  is configured to translate cable  330  rotary motion into transverse (i.e. perpendicular to a central axis C of distal section  314 ), reciprocating motion of work element  304 . According to some embodiments, motion converter  334  may be positioned in distal section  314 . According to some embodiments, some parts of motion converter  334  may be positioned in distal section  314  and other parts of motion converter  334  may be positioned in a bent section  318  joining main section  312  to distal section  314 . More specifically, motion converter  334  includes a cam  342  mechanically associated with work element  304 . Cam  342  may include one or more lobes  346  (four, for example, in  FIG.  3   ) radially (e.g. perpendicularly to the central axis C) extending from a cam body  390 . Cam body  390  may be mounted on a shaft  392  which is mechanically coupled to a cable distal end  338  (i.e. the distal end of cable  330 ). Shaft  392  may extend along, substantially along, or in parallel to, or substantially in parallel to, the central axis C of distal section  314 . According to some embodiments, shaft  392  may be excentric in the sense of being displaced (offset) relative the central axis C, so that cam  342  is also displaced relative to the central axis C. 
     According to some embodiments, main section  312  and bent section  318  are not distinct in the sense that a distal end portion of main section  312  and a proximal end portion of bent section  318  are one and the same. Additionally, or alternatively, according to some embodiments, bent section  318  and distal section  314  are not distinct in the sense that a distal end portion of bent section  318  and a proximal end portion of distal section  314  are one and the same. 
     According to some embodiments, wherein (i) the distal portion of main section  312  and the proximal portion of bent section  318  are one and the same, and (ii) the distal portion of bent section  318  and the proximal portion of distal section  314  are one and the same, bent section  318  may be sharply bent. 
     Motion converter  334  may further include a spring (not shown), such as a leaf spring, which is coupled to work element  304  (and housed within distal section  314 ). The spring may be configured to exert a return force on work element  304  when work element  304  is radially displaced relative to sidewall  388  (i.e. such as to project from sidewall  388 ). 
     In debulking procedure, distal section  314  may first be positioned in parallel to a target tissue surface. The distance between distal section  314  and the tissue surface is selected to be such that when work element  304  is radially projected from distal section  314  (i.e. when transverse, reciprocating motion of work element  304  is effected), eroding surface  364  will strike the tissue surface. When the rotation actuator is switched on, so that cable  330  effects rotary motion, rotary motion of shaft  392 , and hence, of cam  342 , is induced. As cam  342  rotates, each of lobes  346 , in turn, may engage work element  304 , such as to radially push work element  304 , until the force of the spring pulls back work element  304 , which is then engaged again by one of lobes  346 , such that transverse (radial), reciprocating motion of work element  304  is generated. 
     According to some embodiments, distal section  314  includes a first bearing  356  (e.g. a roller bearing), positioned at a distal end  316  of distal section  314 , and a second bearing  386  (e.g. a roller bearing), which may be positioned at a proximal end (not numbered) of distal section  314 . Shaft  392  may be disposed through first bearing  356  and second bearing  386 , which are configured to facilitate shaft  392  rotary motion (cam body  390  is positioned between first bearing  356  and second bearing  386 ). 
     According to some embodiments of the surgical tools disclosed herein (e.g. surgical tools  100 ,  100 ′,  100 ″,  200 , and  300 ), the surgical tools are adapted for debulking hard tissue while leaving intact soft (elastic) tissue (e.g. the mechanical properties of the headpiece/work element and the amplitude and frequency of the reciprocating motion are such that when the headpiece/work element effects reciprocating motion against a bone, it may grind/fragment the bone, but when the headpiece/work element effects reciprocating motion against soft tissue, it will not damage it). 
     Thus, according to an aspect of some embodiments, there is provided a surgical tool, such as surgical tool  100  or surgical tool  200  or similar thereto, for breaking up/fragmenting hard tissue (e.g. bone tissue). The surgical tool includes a hollow member (e.g. a flexible or malleable tube), a cable, a headpiece, a rotation actuator, and a motion converter. The hollow member is elongated and includes a main section and a distal section. The distal section may be positioned at an angle relative to the main section (e.g. to facilitate accessing difficult-to-reach anatomical sites, such as between vertebrae). The cable is elongated and extends within the main section there along from a cable proximal end (i.e. the proximal end of the cable) to a cable distal end (i.e. the distal end of the cable). The cable is configured to resist helixing. The headpiece is positioned in or on the distal section and is configured for axial, reciprocating motion wherein at least some of the headpiece is exposed outside the distal section. The rotation actuator is coupled to the cable proximal end and is configured to effect rotary motion of the cable about a longitudinal axis of the cable. The motion converter is coupled to the cable distal end and to the headpiece. The motion converter is configured to transform rotary motion of the cable into the axial, reciprocating motion of the headpiece. The headpiece may be further configured to break up/fragment hard tissue by hammering of the tissue, when effecting axial, reciprocating motion, while simultaneously minimizing damage to soft tissue if struck. 
     According to some embodiments, wherein the distal section is positioned at an angle relative to the main section, (i) the hollow member further includes a bent section positioned between, or defined by, the main section and the distal section, (ii) the conversion of the rotary motion of the cable into axial, reciprocating motion of the headpiece is generated in the bent section or in proximity thereto. According to some embodiments, the reciprocating motion of the headpiece is generated distally to the bent section. According to some embodiments, the reciprocating motion of the headpiece is generated proximally to the bent section. 
     According to some embodiments, the hollow member may be configured such as to allow controllably changing the angle between the main section and the distal section. 
     According to some embodiments, the bent section is flexible. According some such embodiments, the bent section may be flexible such as to shape-wise adapt to physical (geometrical) constraints within a body of a subject during or a during the surgical procedure. The shape-wise adaptability may potentially aid in reaching difficult-to-access target sites. 
     According to some embodiments, the headpiece may be further configured such as to strike the tissue at a rate of about 10,000-480,000, 20,000-480,000, 50,000-480,000 or any other range within 10,000-480,000 strikes per minute (SPM). Without being bound by any theory, the SPM may be set according to the type of headpiece attached, e.g. whether the headpiece is smooth, eroded or serrated, coated with abrasive material etc. 
     According to some embodiments, at least during the axial, reciprocating motion, the headpiece (also referred to as “cutting head”) distally projects from a distal end of the distal section. 
     According to some embodiments, the headpiece is excentric in the sense of being laterally offset (laterally displaced) relative to a central axis of the distal section. The offsetting of the headpiece may facilitate treatment of sites to which access would otherwise be difficult or require removal of tissue blocking access to the site. 
     According to some embodiments, a distal tip of hollow member includes or constitutes one or more electrodes, being thereby configured for electrophysiological monitoring and/or neurostimulation. According to some such embodiments, the one or more electrodes are configured to function as, a single electrode. The hollow member is thereby configured to allow establishing a voltage between the electrode and an external electrode placed on/in a body of a subject during a hard tissue debulking procedure. According to some alternative embodiments, the one or more electrodes are configured to function as two electrodes. The hollow member being thereby configured to allow establish a voltage difference between the two electrodes. 
     According to some embodiments, at least part of the hollow member—including the distal tip of the hollow member—is made of an electrically conducting material, and wherein the distal tip of the hollow member constitutes the one or more electrodes. 
     According to some embodiments, the motion converter includes a cam and a pushrod (i.e. an elongated cam tracker/follower). The cam is mechanically coupled to the cable distal end. The pushrod is mechanically coupled to the headpiece and is configured to engage the cam and to effect axial, reciprocating motion. 
     According to some embodiments, the headpiece is mounted on a distal end of the pushrod. According to some such embodiments, the headpiece is detachably mounted on the distal end of the pushrod, such as to allow switching between different headpieces varying, for example, in shape and/or dimensions. 
     According to some embodiments, the headpiece and the pushrod are integrally formed with the headpiece constituting the distalmost part of the pushrod. 
     According to some embodiments, the cam is mounted on the cable distal end. According to some such embodiments, the cam is detachably mounted on the cable distal end. 
     According to some embodiments, the hollow member further includes a bent section joined on a first end thereof to the main section and on a second end thereof to the distal section. The cable may extend into the bent section. The cam may be housed in in the bent section. 
     According to some embodiments, a distal end portion of the main section and proximal end portion of the bent section are one and the same. Additionally, or alternatively, according to some embodiments, a distal end portion of the bent section and a proximal end portion of the distal section are one and the same. 
     According to some embodiments, wherein (i) the distal portion of the main section and the proximal portion of the bent section are one and the same, and (ii) the distal portion of the bent section and the proximal portion of the distal section are one and the same, the bent section may be sharply bent (e.g. similarly the spatial relation between two sides of a triangle). 
     According to some embodiments, the motion converter is housed in the distal section or is partially housed in the distal section and partially housed in the bent section. 
     According to some embodiments, at least a portion of the cable, which extends along the bent section, is flexible. 
     According to some embodiments, the surgical tool includes a stopper mechanism configured to restrict axial displacement of the pushrod in at least the distal direction. The stopper mechanism may be positioned in the distal section and/or may constitute a part of the motion converter. 
     According to some embodiments, the pushrod includes a pinhole (i.e. hole) extending from one side-surface thereof to an opposite side-surface thereof The stopper mechanism includes a pin extending through the pinhole from one (inner) sidewall of the distal section to an opposite (inner) sidewall of the distal section. The pinhole is characterized by a diameter which is greater than that of the pin, thereby restricting axial displacement of the pushrod while allowing for axial reciprocating motion of the pushrod. According to some such embodiments, the pin is mounted perpendicularly, or substantially perpendicularly, to the pushrod. 
     According to some embodiments, the distal section includes a linear-motion bearing positioned at the distal end of the distal section with the pushrod extending therethrough. 
     The linear-motion bearing is configured to facilitate the axial, reciprocating motion of the pushrod. 
     According to some embodiments, the motion converter is removably installed, thereby allowing to mount on distal section different tissue-debulking elements, and to switch there between, for example, the motion converter may be used for debulking hard tissue and replaced with a cutting element when soft (elastic) tissue needs to be debulked. 
     According to some embodiments, the cam is irremovably installed on the cam member distal end, while all or some of the remaining components of the motion converter are removably installed. 
     According to some embodiments, the motion converter further includes a sleeve element mountable on and/or in the distal section. The sleeve element includes the pushrod which is at least partially disposed along the sleeve element. 
     According to some embodiments, the cam includes one or more lobes (e.g. rounded projections). Each of the one or more lobes is configured to engage a proximal end of the pushrod when the cam effects rotary motion. According to some such embodiments, each of the one or more lobes may distally projects from a distal end of the cam, such as to facilitate engaging the pushrod. 
     According to some embodiments, a distal end of the cam defines an oblique surface (i.e. angled relative to a lateral cross-section of the bent section), the cam being thereby configured to engage a proximal end of the pushrod when the cam effects rotary motion. 
     According to some embodiments, the pushrod extends in parallel, or substantially in parallel, to a central axis of the distal section (e.g. a rotational symmetry axis of the distal section when the distal section has a circular cross-section and is symmetric, or substantially symmetric, under said rotations). The pushrod may be displaced relative to the central axis of the distal section, thereby facilitating translation of the cam rotary motion into the axial, reciprocating motion of the pushrod. 
     According to some embodiments, the angle between the main section and the distal section is smaller than about 160°. 
     According to some such embodiments, the angle between the main section and the distal section is at least 90°. 
     According to some embodiments, the surgical tool is configured to allow operation thereof when the cable is bent at a bend radius lower than about 15 mm. 
     According to some embodiments, the surgical tool is configured to allow operation thereof when the cable is bent at a bend radius lower than about 12 mm. 
     According to some embodiments, the surgical tool is configured to allow operation thereof when the cable is bent at a bend radius lower than about 10 mm. 
     According to some embodiments, the surgical tool is configured to allow operation thereof when the cable is bent at a bend radius lower than about 9 mm. 
     According to some embodiments, the surgical tool is configured to allow operation thereof when the cable is bent at a bend radius lower than about 5 mm. 
     According to some embodiments, the surgical tool is configured to allow operation thereof when the cable is bent at a bend radius lower than about 2 mm. 
     According to some embodiments, the surgical is configured to allow the cable to generate rotary motion at rates of about 10,000-120,000 RPM, 20.000-120,000 RPM, 40,000-120,000 RPM, or any other range within 10,000-120,000 RPM. 
     According to some embodiments, the surgical tool is configured to generate axial, reciprocating motion of the headpiece such as to allow hammering of hard tissue at rates of about 10,000-480,000 SPM, 20,000-480,000 SPM, or any other range within 10,000-480,000 SPM. More generally, according to some embodiments, the SPM may equal the RPM times n, wherein n is the number of lobes on the cam. 
     According to some embodiments, the cable includes a plurality of wires. According to some such embodiments, the wires are braided/intertwined/stranded (for example, as described with respect to cable  130 ). 
     According to some embodiments, the surgical tool further includes a handle configured to facilitate operation and control of the surgical tool by an operator (e.g. a surgeon). 
     According to some such embodiments, the conversion of the rotary motion of the cable into axial, reciprocating motion of the headpiece is generated distally to the handle. 
     According to some embodiments, the hollow member includes at least two lumens. The cable is disposed along a first lumen (from the at least two lumens). A second lumen (from the at least two lumens) is connected to an operational input (e.g. an electrical port, a port for introducing fluid) and may be configured for the introduction thereinto of e.g. sensing instruments (such as a camera), fluid for irrigating the target tissue site. 
     According to some embodiments, a distal tip of the headpiece includes an eroding surface configured for hammering hard tissue. According to some such embodiments, the eroding surface includes one or more protrusions configured to facilitate the breaking up of the hard tissue. According to some such embodiments, the protrusions may be formed by diamonds embedded on the eroding surface. 
     According to some embodiments, a circumferential surface of the headpiece is eroding, the surgical tool being thereby configured for debulking hard tissue by grating (in addition to, or alternatively to, debulking hard tissue by hammering, as described above). 
     According to some embodiments, the stopper mechanism is at least partially spring-based. 
     According to an aspect of some embodiments, there is provided a method for debulking hard tissue. The method includes providing a surgical tool, such as surgical tool  100 , surgical tool  200 , or a surgical tool similar thereto, as described above. Guiding the distal section of the surgical tool to a target site in a vicinity the hard tissue intended for removal. Positioning the headpiece of the surgical tool in proximity to the hard tissue such as to allow hammering thereof Effecting axial, reciprocating motion of the headpiece such as to hammer and break up/fragment the hard tissue. 
     According to some embodiments, the headpiece of the surgical tool may be positioned adjacently to a surface of the hard tissue such as to allow grating thereof. In such embodiments, in the effecting of the axial, reciprocating motion of the headpiece, the headpiece fragments the hard tissue by grating the surface thereof. 
     According to an aspect of some embodiments, there is provided a surgical tool, such as surgical tool  300  or similar thereto, for breaking up/fragmenting hard tissue (e.g. bone tissue). The surgical tool includes a hollow member, a cable, a work element (e.g. a plate or plate-like element configured for hammering hard tissue), a rotation actuator, and a motion converter. The hollow member is elongated and includes a main section and a distal section. The distal section may be positioned at an angle relative to the main section (such as to facilitate accessing difficult-to-reach anatomical sites, e.g. between vertebrae). The cable is elongated and includes a cable proximal end and a cable distal end. The cable extends within the main section there along and is configured to resist helixing. The work element is exposed on a sidewall of the distal section and is configured for transverse, reciprocating motion, wherein the work element radially projects from the sidewall. The rotation actuator is coupled to the cable proximal end and is configured to rotate the cable about a longitudinal axis of the cable. The motion converter is coupled to both the cable distal end and to the work element. The motion converter includes a rotatable cam and a spring. The work element includes an eroding surface configured for hammering hard tissue and coupled to the spring. The cam includes one or more projections configured to (directly or indirectly) couple to the work element as the cam revolves, such as to laterally push the work element. The spring is configured to exert a return force on the work element when the work element projects from the sidewall. The work element is thereby configured to generate the transverse, reciprocating motion when the cam revolves. 
     According to some embodiments, the spring is a leaf spring. 
     According to some embodiments, the angle between the main section and the distal section is smaller than about 180°. 
     According to some embodiments, the angle between the main section and the distal section is smaller than about 165°. 
     According to some such embodiments, the angle between the main section and the distal section is at least 90°. 
     According to some embodiments, the surgical is configured to allow the cable to generate rotary motion at rates of about 10,000-120,000 RPM, 20.000-120,000 RPM, 40,000-120,000 RPM, or any other range within 10,000-120,000 RPM. 
     According to some embodiments, the surgical tool is configured to generate transverse, reciprocating motion of the work element such as to allow hammering of hard tissue at rates of about 10,000-480,000 SPM, 20,000-480,000 SPM, or any other range within 10,000-480,000 SPM. More generally, according to some embodiments, the SPM may equal the RPM times n, wherein n is the number of projections (e.g. lobes) on the cam. 
     According to an aspect of some embodiments, there is provided a method for debulking hard tissue. The method includes providing a surgical tool, such as surgical tool  300 , or a surgical tool similar thereto, as described above. Guiding the distal section of the surgical tool to a target site in a vicinity the hard tissue intended for removal. Positioning the work element of the surgical tool in proximity to the hard tissue such as to allow hammering thereof. Effecting transverse, reciprocating motion of the work element such as to hammer and break up/fragment the hard tissue. 
     As used herein, according to some embodiments, the term “set” may refer to a collection of elements but also to a single element. Thus, for example, a “set of objects” may refer to one or more objects (e.g. springs). 
     It is appreciated that certain features of the disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the disclosure, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination or as suitable in any other described embodiment of the disclosure. No feature described in the context of an embodiment is to be considered an essential feature of that embodiment, unless explicitly specified as such. 
     Although steps of methods according to some embodiments may be described in a specific sequence, methods of the disclosure may include some or all of the described steps carried out in a different order. A method of the disclosure may include a few of the steps described or all of the steps described. No particular step in a disclosed method is to be considered an essential step of that method, unless explicitly specified as such. 
     Although the disclosure is described in conjunction with specific embodiments thereof, it is evident that numerous alternatives, modifications and variations that are apparent to those skilled in the art may exist. Accordingly, the disclosure embraces all such alternatives, modifications and variations that fall within the scope of the appended claims. It is to be understood that the disclosure is not necessarily limited in its application to the details of construction and the arrangement of the components and/or methods set forth herein. Other embodiments may be practiced, and an embodiment may be carried out in various ways. 
     The phraseology and terminology employed herein are for descriptive purpose and should not be regarded as limiting. Citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the disclosure. Section headings are used herein to ease understanding of the specification and should not be construed as necessarily limiting.