WO2015123548A1

WO2015123548A1 - Rotary surgical cutting tools and powered handpieces

Info

Publication number: WO2015123548A1
Application number: PCT/US2015/015865
Authority: WO
Inventors: Shane S. DEXTER; Zachary HEILIGER
Original assignee: Medtronic, Inc.
Priority date: 2014-02-14
Filing date: 2015-02-13
Publication date: 2015-08-20

Abstract

A rotary-driven surgical cutting tool. The tool includes an elongated shaft carrying a cutting head, and a self-energizing latch. The self-energizing latch is configured to provide a normal state and is further configured to self-transition from a deflected state toward the normal state. A maximum outer dimension of the self-energizing latch in the normal state differs from that in the deflected state. The tool can be quickly connected to the drive chuck of a powered handpiece, with the self-energizing latch effectuating an axial lock with the drive chuck upon insertion. The handpiece can include a coupling assembly for user-prompted release of the tool.

Description

ROTARY SURGICAL CUTTING TOOLS AND POWERED HANDPIECES

Background

[01] The present disclosure relates to rotary-type surgical cutting tools and powered handpieces. More particularly, it relates to rotary surgical cutting tools configured for rapid locked coupling to, and release from, a powered handpiece.

[02] Powered surgical handpieces are commonly used in many medical specialties to drive surgical tools. For example, powered surgical handpieces are used to drive surgical drills, blades or other cutting tools in performing various diverse cutting-type functions including drilling, tapping, resection, dissection, debridement, shaving, pulverizing, and shaping of anatomical tissue including bone. The handpieces are typically configured for selective coupling to, and driving of, a variety of different rotary-type surgical cutting instruments that are each designed to perform a specific procedure. During use, based upon the specific surgical procedure, the surgeon selects the appropriate surgical tool and mounts it to the powered handpiece. The powered handpiece is then operated to drive (e.g., rotate, oscillate, etc.) the tool in performing the surgical procedure. Additional procedural steps can later be performed by mounting a differently- styled tool to the same powered handpiece.

[03] The improved capabilities of powered surgical handpieces, as well as the vast number of surgical cutting tools now available, have undoubtedly greatly increased the number of neurological, spine, ENT/head/neck and other procedures that a surgeon can perform utilizing a single surgical system (i.e., a single powered handpiece with multiple surgical cutting tools). Selective driven coupling between the powered handpiece and each tool is typically effectuated within a housing of the handpiece. The housing carries an internal drive chuck configured to receive a shank or tang of the surgical cutting tool in a mating fashion. Thus, the shank of each surgical cutting tool has a common shape, with this shape corresponding to the handpiece drive chuck (e.g., hexagonal). The drive chuck is connected to (or formed as part of) a drive shaft; upon connection of the surgical cutting tool to the drive chuck, powered rotation of the drive shaft rotates the cutting tool.

[04] While the drive chuck/tool shank interface is well-suited for driven rotation of the surgical cutting tool, the powered handpiece must include additional components to ensure that the cutting tool shank is axially locked at the drive chuck. The surgical cutting tool cannot unexpectedly release from the drive chuck during driven rotation. As a point of reference, many surgical procedures entail rotation of the surgical cutting tool at very high speeds and/or subjecting the cutting end of the tool to forces tending to pull the surgical cutting tool away from the handpiece. To prevent unexpected surgical cutting tool release, the handpiece will include clamp mechanisms that must be tightened by the surgeon (or assistant) when loading the surgical cutting tool, and later loosened by the surgeon when release of the surgical cutting tool is desired. These required actions can unnecessarily extend the surgical procedure. Moreover, while a surgeon will likely, over time, become quite familiar with operation of the clamping mechanism, users may at times be unsure whether the surgical cutting tool has been accurately locked to the handpiece. Under these circumstances, the surgeon will likely repeat the attachment process to ensure correct coupling, again overly extending the overall surgical procedure time.

[05] In light of the above, a need exists for rotary-type surgical cutting tools and corresponding powered handpieces providing quick, reliable, self-locking engagement between the surgical cutting tool and the handpiece.

Summary

[06] Some aspects of the present disclosure relate to a surgical cutting tool adapted to be rotatably driven by a motor. The surgical cutting tool includes an elongated shaft, a cutting head, and a self-energizing latch. The elongated shaft defines a distal region and a proximal region. The cutting head is carried by the distal region. The self-energizing latch is carried by the proximal region. In this regard, the self-energizing latch is configured to provide a first, normal state and is further configured to self-transition from a second, deflected state toward the first state. A maximum outer dimension of the self-energizing latch in the first state is greater differs from the maximum outer dimension in the deflected state. With this construction, the surgical cutting tool can be quickly connected to the drive chuck of a powered handpiece, with the self-energizing latch effectuating an axial lock with the drive chuck upon insertion. In some embodiments, the self-energizing latch is self-expanding, configured to self-transition (or expand) from a collapsed state toward a normal expanded state. In some embodiments, the self-energizing latch is a C-shaped ring. In other embodiments, the self- energizing latch is disposed over a portion of the elongated shaft immediately adjacent a driven surface (e.g., a hexagonal driven surface).

[07] Other aspects of the present disclosure are directed toward a surgical cutting system including a surgical cutting tool and a powered handpiece. The surgical cutting tool includes an elongated shaft and a self-energizing latch as mentioned above. The powered handpiece includes a housing, a drive shaft and a coupling assembly. The drive shaft is rotatably maintained within the housing. The coupling assembly includes a drive chuck disposed within the housing and connected to the drive shaft. The system is configured such that upon initial insertion of the proximal portion of the surgical cutting tool into the housing, the self-energizing latch is forced from the first, normal state to the second, deflected state; with further insertion, the self-energizing latch self-transitions from the deflected state toward the first, normal state to provide an axially locked interface with the drive chuck. In some embodiments, the drive chuck forms a capture chamber sized to maintain the self-energizing latch in the first, normal state. In other embodiments, the powered handpiece further includes an actuator assembly associated with the coupling assembly and configured to force the self-energizing latch from the first, normal state to the second, deflected state while located within the capture chamber.

Brief Description of the Drawings [08] FIG. 1 is an exploded perspective view of a surgical cutting system in accordance with principles of the present disclosure;

[09] FIG. 2 is an enlarged, exploded side view of a portion of a surgical cutting tool in accordance with principles of the present disclosure and useful with the system of FIG. 1 ;

[10] FIG. 3A is a cross-sectional view of an elongated shaft component of the surgical cutting tool of FIG. 2, taken along the line 3A-3A;

[11] FIG. 3B is a cross-sectional view of the elongated shaft of FIG. 2, taken along the line 3B-3B;

[12] FIG. 4A is an enlarged perspective view of a self-energizing latch component of the surgical cutting tool of FIG. 2;

[13] FIG. 4B is an end view of the self-energizing latch of FIG. 4A in a normal state;

[14] FIG. 4C is an end view of the self-energizing latch of FIG. 4A in a deflected state;

[15] FIG. 5A is an enlarged perspective view of a portion of the surgical cutting tool of FIG. 2;

[16] FIG. 5B is a cross-sectional view of the surgical cutting tool of FIG. 5A, taken along the line 5B-5B and illustrating a normal state of the self-energizing latch;

[17] FIG. 5C is a cross-sectional view of the surgical cutting tool of FIG. 5A, taken along the line 5C-5C and illustrating a deflected state of the self-energizing latch;

[18] FIG. 6 A is an enlarged cross-sectional view of a portion of another embodiment surgical cutting tool in accordance with principles of the present disclosure and including a self-energizing latch in a normal state; [19] FIG. 6B is an enlarged cross-sectional view of the portion of FIG. 6A and illustrating the self-energizing latch in a deflected state;

[20] FIG. 7 is a perspective exploded view of another surgical cutting tool in accordance with principles of the present disclosure;

[21] FIG. 8A is a perspective view of a self-energizing latch component of the tool of FIG. 7;

[22] FIG. 8B is a side view of the self-energizing latch of FIG. 8A;

[23] FIG. 9A is a side view of the tool of FIG. 7 upon final assembly;

[24] FIG. 9B is a cross-sectional view of the tool of FIG. 9A, taken along the line 9B-9B, and illustrating a normal state;

[25] FIG. 9C is a cross-sectional view of the tool of FIG. 9A and illustrating a deflected state;

[26] FIG. 10 is a perspective exploded view of another surgical cutting tool in accordance with principles of the present disclosure;

[27] FIG. 11 A is a perspective view of a self-energizing latch component of the tool of FIG. 10;

[28] FIG. 1 IB is a side view of the self-energizing latch of FIG. 11A;

[29] FIG. 12A is a side view of the tool of FIG. 10 upon final assembly;

[30] FIG. 12B is a cross-sectional view of the tool of FIG. 12A, taken along the line 12B-12B, and illustrating a normal state;

[31] FIG. 12C is a cross-sectional view of the tool of FIG. 12A and illustrating a deflected state;

[32] FIG. 12D is a perspective view of another self-energizing latch useful with the tool of FIG. 12A; [33] FIG. 13 is an exploded perspective view of a powered handpiece in accordance with principles of the present disclosure and useful with the system of FIG. 1;

[34] FIG. 14 is an exploded perspective view of a coupling assembly of the powered handpiece of FIG. 13;

[35] FIG. 15A is an enlarged, perspective, cross-sectional view of a drive chuck component of the coupling assembly of FIG. 14;

[36] FIG. 15B is a longitudinal cross-sectional view of the drive chuck of FIG.

15 A;

[37] FIGS. 16A-16D are cross-sectional views illustrating insertion of the surgical cutting tool of FIG. 2 into engagement with the drive chuck of FIG. 15 A;

[38] FIG. 17 is a cross-sectional view of a cap component of the coupling assembly of FIG. 14;

[39] FIG. 18 is an enlarged, perspective, cross-section view of the coupling assembly of FIG. 14;

[40] FIGS. 19A and 19B are cross-sectional views illustrating operation of the coupling assembly of FIG. 18 between locked and release positions; and

[41] FIGS. 20A and 20B are cross-sectional views illustrating the coupling assembly of FIGS. 19A and 19B interfacing with the surgical cutting tool of FIG. 2 in the locked and release positions;

Detailed Description

[42] One embodiment of a surgical cutting system 20 in accordance with principles of the present disclosure is shown in FIG. 1, and includes a rotary surgical cutting tool 22 and a powered handpiece 24. Details on the various components are described below. In general terms, the surgical cutting tool 22 is selectively coupled to the handpiece 24. Once mounted, the powered handpiece 24 is operated to rotate (e.g., rotate in a single direction or oscillate) the surgical cutting tool 22 in performing a desired surgical procedure. Aspects of the present disclosure are directed toward coupling between the surgical cutting tool 22 and the powered handpiece 24, and in particular features provided with one or both of the surgical cutting tool 22 and the powered handpiece 24 that promote locked, releasable assembly in a rapid fashion. In some embodiments, aspects of the present disclosure are embodied by the surgical cutting tool 22 alone; in other embodiments, aspects of the present disclosure are embodied by the powered handpiece 24 alone; and in yet other embodiments, aspects of the present disclosure are embodied by complimentary features provided with both of the surgical cutting tool 22 and the powered handpiece 24.

[43] In some embodiments, the surgical cutting tool 22 includes or provides an elongated shaft 30 and a self-energizing latch 32. The shaft 30 can be formed of a rigid, surgically safe material (e.g., stainless steel), and defines a distal region 34 and a proximal region 36. The distal region 34 forms or carries (e.g., has assembled thereto) a cutting head 38. The cutting head 38 can assume a wide variety of forms appropriate for performing a desired rotary surgical cutting procedure (e.g., cutting, debulking, resecting, or removing anatomical tissue including bone). For example, the cutting head 38 can be a bur having any shape, size, flute pattern, etc., as desired. While the elongated shaft 30 is illustrated as being linear or straight, in other embodiments, the shaft 30 can define one or more longitudinal bends or curves; in related embodiments, surgical cutting tools of the present disclosure can further include an outer sleeve (not shown) that supports the curved shaft 30 as the shaft is rotated.

[44] The proximal region 36 maintains the latch 32 and terminates at a proximal end 40. With additional reference to FIG. 2, the proximal region 36 forms or provides a drive segment 42 and a capture segment 44 adjacent the proximal end 40. The drive segment 42 is configured to engage with and be driven by a corresponding component(s) provided with the powered handpiece 24 as described below. The capture segment 44 is configured to retain the latch 32 and thus incorporates one or more features corresponding with one or more complimentary features provided with the latch 32. In some embodiments, the capture segment 44 is located immediately distal the proximal end 40, and the drive segment 42 is immediately distal the capture segment 44. In other embodiments, locations of the drive and capture segments 42, 44 (relative to a length of the elongated shaft 30) can be reversed; in yet other embodiments, one or both of the drive and capture segments 42, 44 can be distally spaced from the proximal end 40.

[45] The drive segment 42 can incorporate various features for driven engagement with the powered handpiece 24. For example, the proximal region 36 has a longitudinal axis L (it being understood that with embodiments in which the shaft 30 is entirely straight, the longitudinal axis L is linear through the distal region 34). The distal region 34 can be cylindrical, and thus has a circular shape in a plane or cross-section transverse to the longitudinal axis L. As reflected by FIG. 3 A, the drive segment 42 can be non-circular in a plane or cross-section transverse to the longitudinal axis L. For example, in the embodiment shown, the drive segment 42 includes or defines a plurality of surfaces 50 in a plane transverse to the longitudinal axis L, with the surfaces 50 collectively forming a hexagonal shape. Other shapes are also envisioned for driven interface with a corresponding component of the powered handpiece 24 (FIG. 1) (e.g., two-sided flats, triangular, square, double square, pentagon, octagon, etc.). Other drive configurations (e.g., splines, Bristol, tri-lobular, pentalobular, hexalobular, poly drive, circular, etc.) are also acceptable. Regardless, the drive segment 42 defines a maximum outer dimension ODDS in the plane or cross-section transverse to the longitudinal axis L. In some embodiments, the maximum outer dimension ODDS is optionally less than a maximum outer dimension (e.g., outer diameter) of the distal region 34 immediately adjacent the proximal region 36 as reflected by FIG. 3A.

[46] Returning to FIG. 2, features of the capture segment 44 are provided in accordance with a configuration of the self-energizing latch 32 as described below. In one exemplary embodiment, the capture segment 44 is cylindrical, defining a circular shape in a plane or cross-section transverse to the longitudinal axis L as shown in FIG. 3B. A variety of other shapes are also envision, and the capture segment 44 can include (or have assembled thereto) other features that facilitate mounting of the self-energizing latch 32. With the one embodiment of FIG. 3B, a maximum outer dimension (e.g., outer diameter) ODcs of the capture segment 44 is less than the maximum outer dimension OD_Ds of the drive segment 42 for reasons made clear below. Further, and as best shown in FIG. 2, the maximum outer dimension ODcs of the capture segment 44 is less than a maximum outer dimension (e.g., outer diameter) of the proximal end 40 such that first and second shoulders 60, 62 are defined at opposite ends of the capture segment 44.

The self-energizing latches of the present disclosure can assume various forms generally providing a first, normal state and configured to repeatedly self- transition from a second, deflected state to or toward, the first, normal state. In some embodiments, the self-energizing latches of the present disclosure are configured to self-expand from the deflected (e.g., collapsed) state to the normal state; alternatively, in other embodiments, the self-energizing latch is configured to self-collapse from the deflected (e.g., expanded) state to the normal state. With the non-limiting embodiment of FIG. 2, the self-energizing latch 32 is configured to expand in self-transitioning from a deflected state to a normal state. With additional reference to FIG. 4A, the self-energizing latch 32 is or includes a ring or collar body 70 forming a longitudinal slot 72 to define the self-energizing latch 32 as C-shaped in transverse cross-section, with the slot 72 being defined between opposing edges 74, 76 and extending an entire axial length of the self- energizing latch 32 from a distal side 78a to a proximal side 78b. While the self- energizing latch 32 is illustrated as being akin to a right cylinder in the normal expanded state (e.g., a uniform or constant outer diameter) other shapes are also acceptable. For example, the self-energizing latch 32 can be conical, partially conical, or frustoconical in shape, optionally having an elevated outer diameter at or adjacent the distal side 78a. With the C clip-like construction, the self- energizing latch 32 is readily deflected (e.g., collapsed) from the first, normal state of FIGS. 4A and 4B to the second, deflected state of FIG. 4C (in which the opposing edges 74, 76 are forced toward one another). Relative to a plane or cross-section transverse to a centerline of the ring body 70 (and thus relative to the longitudinal axis L (FIG. 2) upon final assembly), a maximum outer dimension OD_L of the self-energizing latch 32 in the first, normal state (FIG. 4B) is greater than in the second, deflected state (FIG. 4C). The ring body 70 is formed of a hardened yet resilient material (e.g., spring steel) such that upon removal of the external forces otherwise forcing the self-energizing latch 32 to the deflected state, the ring body 70 readily self-transitions from the deflected state to or toward the first, normal state. In other words, the self-energizing latch 32 can be forced to a smaller maximum outer dimension multiple times, and then self-returns to the normal, larger maximum outer dimension multiple times. The ring body 70 can be made of a material differing from that of the elongated shaft 30 (and in particular the cutting head 38). For example, the cutting head 38 can be tool steel whereas the ring body 70 is spring steel, molded plastic, etc.

Geometrical relationships established between the elongated shaft 30 and the self-energizing latch 32 are shown in FIGS. 5A and 5B. In the first, normal state of the self-energizing latch 32 (reflected by FIGS. 5 A and 5B), the self- energizing latch 32 is co-axially disposed over the capture segment 44. An inner diameter of the ring body 70 (in the normal state) is larger than the maximum outer dimension ODcs (e.g., outer diameter) of the capture segment 44 such that the self-energizing latch 32 can be collapsed on to the capture segment 44 as described below. However, the inner diameter of the ring body 70 is less than the diameters (or other outer dimension) established at the shoulder 60, 62 such that the self-energizing latch 32 is longitudinally constrained between the shoulders 60, 62. Further, the maximum outer diameter OD_L of the self-energizing latch 32 (in a plane or cross-section transverse to the longitudinal axis L) is larger than the maximum outer dimension (e.g., outer diameter) of at least the proximal end 40 and the maximum outer dimension OD_DS of the drive segment 42 for reasons made clear below. With this construction, the self-energizing latch 32 can be compressed or collapsed relative to the capture segment 44 to the deflected state illustrated in FIG. 5C, with the maximum outer dimension OD_L approximating the maximum outer dimension of the proximal end 40. Upon removal of the collapsing force, the self-energizing latch 32 self-reverts back to the first, normal state of FIG. 5B. While the self-energizing latch 32 is shown as being loosely maintained over the capture segment 44, in other embodiments a more robust attachment can be provided (e.g., weld, adhesive, etc.).

[49] The surgical cutting tools of the present disclosure can incorporate other self-energizing latch configurations. For example, FIG. 6A illustrates portions of another surgical cutting tool 22A in accordance with principles of the present disclosure. The surgical cutting tool 22A includes the elongated shaft 30 and a self-energizing latch 32A. The self-energizing latch 32A is maintained along the proximal region 36 of the shaft 30, with the proximal region 36 forming the drive and capture segments 42, 44 in accordance with the above descriptions.

[50] The self-energizing latch 32A is configured to be repeatedly deflected

(e.g., collapsed or compressed) from the first, normal state of FIG. 6A to a second, deflected state, an example of which is shown in FIG. 6B, and self- transition or self-revert back to the first, normal state. The self-energizing latch 32A includes or defines a base 80 and one or more spring fingers 82. The base 80 is configured for assembly to the capture segment 44 (e.g., weld, adhesive, etc.), and can have ring shape. Each of the spring fingers 82 projects from the base 80, and terminates at tip 84 opposite the base 80. The spring fingers 82 are biased relative to the base 80 in the arrangement reflected by FIG. 6A, with the tips 84 being transversely or radially off-set from the base 80. That is to say, relative to a longitudinal axis L of the proximal region 36 (and thus a centerline of the base 80), the spring fingers 82 project radially or transversely outwardly in distal extension from base 80. With this construction, the tips 84 combine to define a maximum outer dimension ODLA of the self-energizing latch 32A in a plane or cross-section transverse to the longitudinal axis L. In the first, normal state, the maximum outer dimension OD_LA of the self-energizing latch 32A is greater than at least the maximum outer dimension (e.g., outer diameter) of the proximal end 40 of the shaft 30, and is greater than the maximum outer dimension OD_Ds of the drive segment 42. [51] The self-energizing latch 32A is formed of a structurally robust material exhibiting a shape memory attribute capable of retaining a shape of the first, normal state, as well as structural integrity when forced to a deflected state. For example, the self-energizing latch 32A can be stamped steel, molded plastic, etc.

[52] Yet another embodiment surgical cutting tool 22B in accordance with principles of the present disclosure is shown in FIG. 7. The surgical cutting tool 22B includes an elongated shaft 30B and a self-energizing latch 32B. The self- energizing latch 32B is maintained over the elongated shaft 30B as described below.

[53] The elongated shaft 30B can have any of the constructions described above, and generally includes a distal region 34B and a proximal region 36B. The distal region 34B forms or is connected to a cutting head 38B (drawn generally). The proximal region 36B terminates at a proximal end 40B, and defines a drive segment 42B and a capture segment 44B. The drive segment 42B can assume any of the forms described above with respect to the drive segment 42 (FIG. 3A). The capture segment 44B is generally configured to receive the self-energizing latch 32B, and has an outer diameter (or other outer dimension) less than that of the drive segment 42B. In some embodiments, the capture segment 44B is optionally axially spaced from the drive segment 42B and the proximal end 40B by intermediate segments 86a, 86b. The intermediate segments 86a, 86b can have an outer diameter greater than that of the capture segment 44B to establish shoulders 60B, 62B.

[54] The self-energizing latch 32B can be self-expanding as shown in greater detail in FIGS. 8A and 8B, and generally includes or defines a collar 88, a first finger 90 and a second finger 92. The collar 88 can have a split ring construction for assembly over the capture segment 44B (FIG. 7) (e.g., an inner diameter of the collar 88 approximates an outer diameter of the capture segment 44B). Regardless, the collar 88 defines opposing, distal and proximal ends 94a, 94b.

[55] The first finger 90 projects from the collar 88 in a direction of the distal end 94a and terminates at a tip 96. In the first, normal state of FIGS. 8A and 8B, extension of the first finger 90 relative to the collar 88 has a radial component, with the tip 96 being radially displaced from an outer diameter of the collar 88. When subjected to an external compressive force, the first finger 90 can deflect inwardly (e.g., pivoting at the point of connection with the collar 88), including the tip 96 being brought into alignment with the outer diameter of the collar 88. When the external force is removed, the first finger 90 self-reverts back to the radially outwardly extending arrangement of FIGS. 8 A and 8B.

[56] The second finger 92 is defined by a cut-out in the collar 88, and forms a central section 98. In the first, normal state of FIGS. 8 A and 8B, the second finger 92 assumes the bulged or deflected arrangement shown, with the central section 98 projecting radially outwardly relative to the collar 88. Stated otherwise, the central section 98 is radially displaced from the outer diameter of the collar 88. When subjected to an external compressive force, the second finger 92 readily deflects, bringing the central section 98 into alignment with an outer diameter of the collar 88. When the external force is removed, the second finger 92 self-reverts back to the bulged or radially outwardly extending arrangement of FIGS. 8A and 8B.

[57] While the first and second fingers 90, 92 have been described as having differing constructions, in other embodiments the fingers 90, 92 can be identical (e.g., both fingers 90, 92 can have the construction of the first finger 90 as shown, or can have the construction of the second finger 92). Further, more than two of the finger 90, 92 can be provided. Regardless, the fingers 90, 92 collectively define a maximum outer dimension OD_L of the self-energizing latch 32B. The maximum outer dimension OD_L can be reduced by subjecting the fingers 90, 92 to a compressive force, for example bringing the fingers 90, 92 into alignment with the outer diameter of the collar 88 (e.g., in a defiected state, the maximum outer diameter OD_L approximates the outer diameter of the collar 88).

[58] The surgical cutting tool 22B is shown in final assembled form in FIGS.

9A and 9B. The self-energizing latch 32B is co-axially disposed over the capture segment 44B (hidden in FIG. 9A, but shown in FIG. 7) of the elongated shaft 30B, with the opposing ends 94a, 94b captured against the shoulders 60B, 62B, respectively. Alternatively, the self-energizing latch 32B can be more rigidly affixed to the elongated shaft 30B (e.g., welded). As best shown by FIG. 9B, in the first, normal state of the self-energizing latch 32B, the fingers 90, 92 extend radially beyond an outer diameter of the proximal region 36B (FIG. 9A) of the elongated shaft 3 OB. That is to say, the maximum outer dimension ODL of the self-energizing latch 32B is greater than a maximum outer diameter of the proximal region 36B. The self-energizing latch 32B can be forced to the second, deflected state of FIG. 9C in which the maximum outer dimension OD_L is reduced. Upon removal of the external force, the self-energizing latch 32B self- reverts or self-transitions back to the first, normal state of FIG. 9B.

[59] Yet another embodiment surgical cutting tool 22C in accordance with principles of the present disclosure is shown in FIG. 10. The surgical cutting tool 22C includes an elongated shaft 30C and a self-energizing latch 32C. The self- energizing latch 32C is maintained over the elongated shaft 30C as described below.

[60] The elongated shaft 30C can have any of the constructions described above, and generally includes a distal region 34C and a proximal region 36C. The distal region 34C form or is connected to a cutting head 38C (drawn generally). The proximal region 36C terminates at a proximal end 40C, and defines a drive segment 42C and a capture segment 44C. The drive segment 42C can assume any of the forms described above. The capture segment 44C is generally configured to receive and maintain the self-energizing latch 32C. For example, the capture segment 44C can form or define opposing first and second platform surfaces 100, 102, opposing first and second receiving surfaces 104, 106, and opposing first and second tabs 108, 110. The first platform surface 100 and the first receiving surface 104 can be substantially flat and substantially coplanar, with the first tab 108 formed as an outward projection between the first platform and receiving surfaces 100, 104. A similar relationship is established by the second platform surface 102, the second receiving surface 106, and the second tab 110. As described below, the tabs 108, 110 are configured to retain the self-energizing latch 32C, with the first and second platform surface 100, 102 shaped and located to facilitate desired deflection.

[61] The self-energizing latch 32C is shown in greater detail in FIGS. 11 A and

11B, and generally includes or defines opposing, spaced apart arms 112, 114 interconnected at a base 116. A finger 118, 120 projects distally from each of the arms 112, 114, respectively, in a direction opposite the base 116. For example, the first finger 118 is connected to the first arm 112 at a trailing end 122 and terminates at a tip 124. The first finger 118 optionally tapers in width from the trailing end 122 to the tip 124. Regardless, in the first, normal state of FIGS. 11 A and 11B, extension of the first finger 118 includes a radially or transversely outward component such that the tip 124 is radially or transversely displaced from a plane of the first arm 112. A similar relationship is established between the second arm 114 and the second finger 120, with the second finger 120 extending from a trailing end 126 to a tip 128 that, in the first, normal state, is radially or transversely displaced beyond a plane of the second arm 114.

[62] The arms 112, 114 can each form or define an aperture 130 sized and shaped to receive and frictionally engage a corresponding one of the tabs 108, 110 (FIG. 10). A slot 132 extending through the base 116 and a portion of each of the arms 112, 114 can also be provided to facilitate assembly over the proximal end 40C (FIG. 10) of the elongated shaft 30C (FIG. 10). In other embodiments, the self-energizing latch 32C can incorporate other features that correspond with features of the elongated shaft 30C and promote mounted assembly that may or may not include one or more of the apertures 130 or the slot 132.

[63] The tips 124, 128 collectively define a maximum outer dimension OD_L of the self-energizing latch 32C. When subjected to an external compressive force, the fingers 118, 120 can deflect inwardly (e.g., pivoting at the corresponding trailing end 122, 126) including the tips 124, 128 being brought into general alignment with the plane of the corresponding arm 112, 114. When the external force is removed, the fingers self-revert or self-transition back to the first, normal state of FIGS. HA and 11B.

[64] FIGS. 12A and 12B illustrate the surgical cutting tool 22C upon final assembly. The self-energizing latch 32C is assembled to the elongated shaft 30C at the capture region 46C, for example by inserting the proximal end 40C through the slot 132 (FIGS. 11A and 11B). The first arm 112 is held against the first platform and receiving surfaces 100, 104 via the first tab 108 (best seen in FIG. 10), whereas the second arm 114 is held against the second platform and receiving surfaces 102, 106 via the second tab 110 (best seen in FIG. 10).

[65] As best reflected by FIG. 12B, in the first, normal state of FIG. 12B, the fingers 118, 120 extend radially or transversely outwardly (in opposite directions) beyond an outer dimension of the proximal region 36C of the elongated shaft 30C. That is to say, the maximum outer dimension OD_L of the self-energizing latch 32C is greater than a maximum outer dimension of the proximal region 36C. The self-energizing latch 32C can be forced to the second, deflected state of FIG. 12C in which the maximum outer dimension ODL is reduced. Deflection of the fingers 118, 120 can include the corresponding trailing end 122, 126 (FIG. 11B) bearing against the corresponding platform surface 100, 102 to promote inward deflection of the tips 124, 128 (FIG. 1 IB). Upon removal of the external force, the self-energizing latch 32C self-reverts or self-transitions back to the first, normal state of FIG. 12B.

[66] Another embodiment of a self-energizing latch 32D useful with the elongated shaft 30C is shown in FIG. 12D. The self-energizing latch 32D is similar to the self-energizing latch 32C, and includes opposing fingers 140, 142 that can be repeatedly deflected from the first, normal state shown to a deflected state, and self-revert back to the first, normal state.

[67] Returning to FIG. 1, the powered handpiece 24 includes one or more features configured to interface with the surgical cutting tools of the present disclosure, including the self-energizing latches, in selectively loading and releasing the surgical cutting tool, as well as other components for rotatably driving a loaded surgical cutting tool. In this regard, the powered handpieces of the present disclosure can employ various drive assemblies or motors (e.g., pneumatically powered or driven, electrically powered or driven, etc.) for effectuating driven rotation at desired speeds.

[68] With the above general parameters in mind, portions of one embodiment of the powered handpiece 24 are shown in FIG. 13. The handpiece 24 includes a housing 200 maintaining various internal components (hidden) for effectuating coupling of the surgical cutting tool 22 (FIG. 1) to a primary drive shaft 202. The housing 200 can assume a variety of forms, shapes and sizes, and in some embodiments can comprise two or more housing segments assembled to one another. For example, FIG. 13 illustrates two housing sections 204, 206. The first housing section 204 is configured for assembly to the second housing section 206 (e.g., via a threaded surface 208), and forms a tube 210 forming a passageway 212 sized to slidably receive the proximal region 36 (FIG. 2) of the surgical cutting tool 22. The tube 210 forms a nose of the powered handpiece 24 upon final assembly to the second housing section 206. As a point of reference, the second housing section 206 is illustrated in FIG. 13 as optionally being assembled to third and fourth housing sections 214, 216.

[69] One of skill will understand that powered handpieces of the present disclosure optionally include various internal components and mechanisms for supporting the surgical cutting tool 22 (FIG. 1) within the passageway 212 during high speed driven rotation, as well as supporting other components (e.g., the primary drive shaft 202, couplings connecting the primary drive shaft 202 to the surgical cutting tool 22, etc.) as the drive shaft 202 is rotated or oscillated. Thus, while multiple rotational support components (e.g., ball bearing assemblies, spacers, springs, etc.) can be included with the powered handpiece 24, detailed explanations of such components are omitted from the description below as unnecessary for understanding basic construction and operation. Aspects of the present disclosure implicate features of the powered handpiece 24 that effectuate coupling with the cutting tool, including quick connection and easy release. [70] One embodiment of a coupling assembly 230 in accordance with principles of the present disclosure and useful for selectively coupling the surgical cutting tool 22 (FIG. 1) to the primary drive shaft 202 is shown in FIG. 14. The coupling assembly 230 includes a drive chuck 232, one or more bearing members 234, a cap 236, a biasing device 238, and an optional transition body 240. The drive chuck 232 is configured to receive and engage the surgical cutting tool 22 in a rotationally and longitudinally (or axially) locked fashion. The bearing members 234 are retained within the cap 236, and function to selectively engage and facilitate release of the surgical cutting tool 22 from the longitudinally locked arrangement relative to the drive chuck 232 with movement of the cap 236 from a locked position to an unlocked position. In this regard, the biasing device 238 biases the cap 236 to the locked position. The transition body 240, where provided, connects the drive chuck 232 with the primary drive shaft 202.

[71] The drive chuck 232 forms various features (e.g. surfaces) to receive and engage the surgical cutting tool 22 (FIG. 1). As shown in FIGS. 15A and 15B, in one embodiment the drive chuck 232 can be viewed as having or defining a leading portion 250, a drive portion 252, a capture portion 254 and a trailing portion 256. The drive chuck 232 is a generally tubular body, defining a central passage 258 that extends from (and is open at) a leading end 260 of the leading portion 250 through at least the drive and capture portions 252, 254. In some embodiments, the passage 258 optionally extends through the trailing portion 256. Regardless, various features and/or geometries are formed along an interior surface of the drive chuck 232 in defining the central passage 258 and relative to a central axis A.

[72] For example, a diameter of the passage 258 along the leading portion 250 can be relatively uniform in initial extension from the leading end 260, and is generally sized to approximate or be slightly larger than the maximum outer dimension ODL (FIG. 5B) of the self-energizing latch 32 (FIG. 5B) in the first, normal state. The leading portion 250 forms ledge or deflection inducing surface 262 adjacent the drive portion 252 and along which the diameter of the central passage 258 tapers or decreases (relative to the central axis A). At an intersection of the leading portion 250 and the drive portion 252, the diameter of the central passage 258 is less than the maximum outer dimension ODL of the self- energizing latch 32 in the first, normal state for reasons made clear below.

[73] The drive portion 252 forms the central passage 258 in accordance with the drive segment 42 (FIG. 2) of the surgical cutting tool 22 (FIG. 1). More particularly, engagement faces 264 are defined along the central passage 258 at the drive segment 252, sized and shaped to engage corresponding ones of the drive surfaces 50 (FIG. 3A) of the surgical cutting tool 22. Thus, the engagement faces 264 can collectively define a hexagonal shape in transverse cross-section, corresponding with the hexagonal shape and geometry of the surgical cutting tool drive segment 42. In other embodiments, the drive portion 252 (and the surgical cutting tool 22) can incorporate other complimentary constructions conducive to rotationally locked interface therebetween; the present disclosure is in no way limited to a hex-type coupling.

[74] The capture portion 254 is configured to selectively capture and lock (in the longitudinal or axial direction) the surgical cutting tool 22 (FIG. 1) relative to the drive chuck 232 as explained in greater detail below. The capture portion 254 forms a leading shoulder or blocking 270 opposite a trailing shoulder or blocking 272. The leading shoulder 270 is located immediately adjacent the drive portion 252, and represents an increase in a diameter of the central passage 258. In other words, the diameter of the central passage 258 at the capture portion 254 is greater than the diameter along the drive portion 252. The diameter of the central passage 258 can be substantially uniform between the leading and trailing shoulders 270, 272 to define a capture chamber 273, and is selected to approximate the maximum outer dimension OD_L (FIG. 5B) of the self-energizing latch 32 (FIG. 5B) in the first, normal state. The trailing shoulder 272 represents a decrease in the diameter of the central passage 258 such that at the trailing shoulder 272, the diameter of the central passage 258 is less than the maximum outer dimension OD_L of the self-energizing latch 32, and optionally less than an outer dimension or outer diameter of the proximal end 40 (FIG. 2) of the surgical cutting tool 22. In this regard, a longitudinal length of the capture chamber 273 corresponds with a length of the capture segment 44 (FIG. 2) of the surgical cutting tool 22 in some embodiments as made clear below. One or more holes 274 are formed through a thickness of the drive chuck 232 along the capture portion 254. The holes 274 are open to the capture chamber 273 and are each sized in accordance with a dimension of a corresponding one of bearing members 234 (FIG. 14). More particularly, the holes 274 are sized to receive or seat a respective one of the bearing members 234, locating a portion of the corresponding bearing member 234 partially within the capture chamber 273.

[75] The trailing portion 256 projects from the capture portion 254 and can incorporate various features for assembly to the transition body 238 (FIG. 14). For example, in one non-limiting embodiment, the trailing portion 256 can form a post 280 sized for assembly (e.g., press-fit mounting) to the transition body 238. A wide variety of other constructions are equally acceptable, and in some embodiments, the post 280 can be omitted. For reasons made clear below, a flange 282 is optionally formed by the trailing portion 256, and represents a radially outward projection adjacent the capture portion 258.

[76] FIGS. 16A-16D illustrate an interface between the surgical cutting tool 22 and the drive chuck 232 with progressive insertion of the surgical cutting tool 22 into the drive chuck 232. It will be understood that the powered handpiece 24 (FIG. 1) can include multiple other components that interface with the surgical cutting tool 22 and/or support the drive chuck 232 (or other components of the coupling assembly 230 (FIG. 14); for ease of understanding, the views of FIGS. 16A-16D illustrate the drive chuck 232 and a portion of the surgical cutting instrument 22 in isolation.

[77] In the arrangement of FIG. 16A, the surgical cutting tool 22 is poised for insertion into the drive chuck 232 (it being understood that at the stage of insertion reflected in FIG. 16A, the surgical cutting tool 22 may previously have been inserted into other components of the powered handpiece 24 (FIG. 1) that serve to guide the surgical cutting tool 22 toward the drive chuck 232, for example the first housing section 204 (FIG. 13)). More particularly, the proximal end 40 is longitudinally or axially aligned with the central passage 258 at the leading end 260. The self-energizing latch 32 is in the first, normal state. As a point of reference, the maximum outer dimension ODL (FIG. 5B) of the self- energizing latch 32 is slightly less than a diameter of the central passage 258 at the leading end 260.

[78] As the surgical cutting tool 22 is moved toward the drive chuck 232

(and/or vice-versa) in the direction of the arrow in FIG. 16A, the proximal end 40 enters the central passage 258 and traverses along the leading portion 250 to the arrangement of FIG. 16B. As shown, the self-energizing latch 32 is longitudinally brought into contact with the ledge 262 of the leading portion 250. A diameter of the central passage 258 tapers along the ledge 262, decreasing to a diameter that is less than the maximum outer dimension OD_L (FIG. 5B) of the self-energizing latch 32. As a result, with further continued proximal movement of the surgical cutting tool 22 relative to the drive chuck 232, the self-energizing latch 32 bears against the ledge 262 and is forced to deflect (e.g., compress or collapse) toward or against the capture segment 44 of the elongated shaft 30. The maximum outer dimension OD_L of the self-energizing latch 32 is thereby reduced, permitting the self-energizing latch 32 to slide into the drive portion 252 (along which the diameter of the central passage 258 is reduced as compared to the diameter along a majority of the leading portion 250) as reflected by FIG. 16C.

[79] As the surgical cutting tool 22 is further directed proximally relative to the drive chuck 232, the self-energizing latch 32 is maneuvered proximally beyond the drive portion 252 and into the capture chamber 273 as shown in FIG. 16D. In the locked condition of FIG. 16D, the proximal end 40 of the elongated shaft 30 abuts the trailing shoulder 272, serving to stop further proximal movement of the surgical cutting tool 22 relative to the drive chuck 232. A longitudinal or axial length of the capture chamber 273 corresponds with (e.g., is slightly greater than) a longitudinal distance between the proximal end 40 and the distal side 78a of the self-energizing latch 32 such that in the locked condition of FIG. 16D, the self-energizing latch 32 is entirely within the capture chamber 273. For example, with the proximal side 78b of the self-energizing latch 32 contacting the proximal end 40 of the elongated shaft 30 and the proximal end 40 bearing against the trailing shoulder 272, the distal side 78a is proximal the leading shoulder 270. Once located within the larger diameter capture chamber 273 (as compared to the diameter of the central passage 258 along the drive portion 252), the self-energizing latch 32 is no longer directly compressed by surfaces of the drive chuck 232 and self-transitions (e.g., expands) to or toward the first, normal state as shown. The maximum outer dimension OD_L (FIG. 5B) of the self-energizing latch 32 in the first, normal state is greater than a diameter of the leading shoulder 270. Thus, once in the first, normal state, the leading shoulder 270 prevents passage of the self-energizing latch 32 in the opposite or distal direction relative to the drive chuck 232, effectuating a longitudinal or axial lock between the surgical cutting tool 22 and the drive chuck 232. As a point of reference, FIG. 16D further reflects a rotational lock between the surgical cutting tool 22 and the drive chuck 232 in the locked condition via interface between the drive surfaces 50 (referenced generally) of the surgical cutting tool 22 and the engagement faces 264 (referenced generally) of the drive chuck 232.

Other engagement formats can be employed to effectuate a rotational and longitudinal lock between the surgical cutting tool 22 and the drive chuck 232 in accordance with principles of the present disclosure (e.g., any of the alternative self-energizing latch constructions described above are equally useful; the drive chuck 232 can provide differently configured surfaces for selectively engaging the self-energizing latch; etc.). With the exemplary embodiments shown, the surgical cutting tool 22 is readily and quickly brought into a locked relationship with the drive chuck 232 by simply inserting and sliding the surgical cutting tool 22 relative to the drive chuck 232 (and/or vice-versa), and thus relative to the powered handpiece 24 (FIG. 1). Further, embodiments of the present disclosure generate a tactile and/or audible confirmation to the user when the locked condition has been attained (e.g., a user cannot pull the surgical cutting tool 22 from the powered handpiece 24, a user may sense or "feel" the self-energizing latch 32 self-transitioning to the first, normal state when grasping the elongated shaft 30, an audible "click" may be generated by the self-energizing latch 32 in self-transitioning to or toward the first, normal state, etc.).

[81] Returning to FIG. 14, other components of the coupling assembly 230 are provided to afford a user the ability to release the surgical cutting tool 22 (FIG. 11) from the locked position relative to the drive chuck 232 by selectively biasing or forcing the self-energizing latch 32 (FIG. 16D) from the first, normal state while in the capture chamber 273 (FIG. 16D). For example, the bearing members 234, the cap 236, and the biasing device 238 are sized and shaped in accordance with geometries of the drive chuck 232, with the cap 236 being generally configured to retain the bearing members 234 relative to an exterior of the drive chuck 232. As described below, the bearing members 234 are generally configured to bear against interface with self-energizing latch 32 (FIG. 1), and can assume a variety of forms. In some embodiments, the bearing members 234 are metal balls or ball bearings.

[82] With additional reference to FIG. 17, the cap 236 is a tubular body defining a passageway 290. The passageway 290 is open at opposing, first and second ends 292, 294 of the cap 236, and is generally sized in accordance with an outer diameter of the drive chuck 232. In this regard, the cap 236 can be viewed as defining a head 296, a neck 298 and a foot 300. A diameter of the passageway 290 is substantially uniform along the neck 298, sized to slidably receive the drive chuck 232. The head 296 forms the passageway 290 at the first end 292 to have a reduced diameter (relative to the diameter along the neck 298), sized to be smaller than diameter of the drive chuck 232. Conversely, a diameter of the passageway 290 along the foot 300 is increased (relative to the diameter long the neck 298), with the foot 300 defining the passageway 290 along a ramp 302 and a skirt 304. The passageway 290 has an increasing diameter along the ramp 302 in extension from the neck 298, and a relatively uniform diameter along the skirt 304 to the second end 294 (with the diameter of the passageway 290 along the skirt 304 being greater than the diameter along the neck 298) for reasons made clear below. [83] Returning to FIG. 14, the biasing device 238 can assume various forms, and in some embodiments is a spring. The spring 238 is sized to be received over the drive chuck 232, nested between the flange 282 of the drive chuck 232 and the second end 294 of the cap 236.

[84] As mentioned to above, the transition body 240 is an optional component that serves to interconnect the drive chuck 232 with the primary drive shaft 202. Thus, the transition body 240 can assume a wide variety of forms. In the non- limiting embodiment shown, the transition body 240 forms a tube 310 sized to receive the post 280 of the drive chuck 232, and a hub 312 sized for assembly over a distal section 314 of the primary drive shaft 202. In yet other embodiments, the transition body 240 can be omitted (e.g., the drive chuck 232 is directly attached to, or is integrally formed by, the primary drive shaft 202).

[85] FIG. 18 illustrates the coupling assembly 230 upon final construction and connected to the primary drive shaft 202. The hub 312 of the transition body 240 is mounted over the distal section 314 of the primary drive shaft 202. The post 280 of the drive chuck 232 is mounted within the tube 310 of the transition body 240. The bearing members 234 are partially disposed within respective ones of the holes 274 in the drive chuck 232. The cap 236 is co-axially disposed over an exterior of the drive chuck 232, capturing the bearing members 234 relative to the drive chuck 232. The biasing member 238 is disposed over the drive chuck 234, lodged between the flange 282 of the drive chuck 232 and the second end 294 of the cap 236. With this arrangement, the biasing member 238 biases the cap 236 longitudinally or axially away from the flange 282 to the locked position illustrated in FIG. 18. In the locked position, the cap 236 is arranged relative to the drive chuck 232 such that the bearing members 234 are not overtly forced through the corresponding hole 274 and into the capture chamber 273. For example, in some embodiments, the skirt 304 of the cap 236 is aligned with or over the bearing members 234 in the locked position. The locked position is further illustrated in FIG. 19A and reflects that due to the relatively large diameter of the passageway 290 along the skirt 304 (as compared to the diameter along the ramp 302 and the neck 298), the bearing members 234 can be directed radially outwardly from the capture chamber 273 as described below. In other embodiments, the locked position includes the cap 236 longitudinally arranged such that the ramp 302 is radially aligned with the bearing members 234 but with the cap 236 in a relaxed condition in which the cap 236 does not overtly force the bearing members 234 into the corresponding hole 274.

[86] The coupling assembly 230 can be transitioned to the release position shown in FIG. 19B by forcing the cap 236 proximally relative to the drive chuck 232 and/or by forcing the drive chuck 232 distally relative to the cap 236 (with a force sufficient to overcome a bias force of the biasing member 238). In the release position, the cap 236 is longitudinally arranged relative to the drive chuck 232 such that the ramp 302 is aligned with or over the bearing members 234. Due to the tapering diameter of the passageway 290 along the ramp 302, the ramp 302 interfaces with the bearing members 234, forcing the bearing members 234 radially inwardly and partially through the corresponding hole 274 in the drive chuck 232. As a result, in the release position, the bearing members 234 are forced into, and rigidly maintained (by the cap 236) within the capture chamber 273. In other embodiments, the release position can be achieved by applying a compressive force on to the foot 300 with the foot 300, in turn, forcing the bearing members 234 into the corresponding hole 274.

[87] Interface of the coupling assembly 230 with the surgical cutting tool 22 in the locked and release positions is illustrated in FIGS. 20 A and 20B. In the arrangement of FIG. 20A, the surgical cutting tool 22 has been fully inserted into the drive chuck 232 as described above, and the cap 236 is in the locked position. Once again, the self-energizing latch 32 self-assumes the first, normal state shown. In the locked position, the bearing members 234 are not overtly forced into the corresponding holes 274 and thus are freely biased or forced out of the capture chamber 273 by the self-energizing latch 32. In other words, in the locked position, the bearing members 234 do not impede the self-energizing latch 32 in self-transitioning to the first, normal state upon being fully disposed or inserted within the capture chamber 273. Thus, with the coupling assembly 230 in the locked position and the self-energizing latch 32 in the first, normal state, the surgical cutting tool 22 is positively locked in the longitudinal or axial direction as described above, with the leading shoulder 270 preventing distal movement of the surgical cutting tool 22 relative to the drive chuck 232 (via abutment with the distal side 78a of the self-energizing latch 32) and the trailing shoulder 272 preventing proximal movement of the surgical cutting tool 22 relative to the drive chuck 232 (via abutment with the proximal end 40 of the elongated shaft 30). Notably, the biasing member 238 biases the cap 236 to the locked position of FIG. 20A as described above such that unless a positive action is taken by a user to transition the coupling assembly 230 to the release position, the coupling assembly 230 will naturally remain in the locked position (with the surgical cutting instrument 22 positively locked to the drive chuck 232 (and thus to the powered handpiece 24 (FIG. 1)).

The surgical cutting tool 22 can be released from the drive chuck 232 in some embodiments by sliding the cap 236 relative to the drive chuck 232, and/or vice-versa, to the release position shown in FIG. 20B. In the release position, the cap 236 positively forces (via interface with the ramp 302) the bearing members 234 partially through the corresponding hole 274 and radially into the capture chamber 273. In other embodiments, the drive chuck 232 and the cap 236 can be held stationary relative to one another, with the release mechanism configured to exert a compressive force onto the cap 236. Regardless, the bearing members 234 are caused to bear against the self-energizing latch 32, compressing or collapsing the self-energizing latch 32 to the deflected state. The extent to which the bearing members 234 deflect the self-energizing latch 32 corresponds with a diameter of the drive portion 252. More particularly, the self-energizing latch 32 is sufficiently deflected to a maximum outer dimension that approximates (e.g., is slightly less than) a diameter of the central passage 258 along the drive chuck drive portion 252. In the deflected state, the self-energizing latch 32 can slide into the drive portion 252. With the coupling assembly 230 in the release position and thus the self-energizing latch 32 in the second, deflected state, the surgical cutting tool 22 can be removed or released from the drive chuck 232 (and thus from the powered handpiece 24 (FIG. 1)) by pulling or sliding the surgical cutting tool 22 distally from the drive chuck 232. [89] A number of mechanisms can optionally be provided with the powered handpiece 24 (FIG. 1) configured to allow a user to actuate or transition the coupling assembly 230 from the locked position to the release position. Further, the powered handpieces of the present disclosure can include various other components or mechanisms as known in the art and appropriate for operating the powered handpiece in driving a surgical cutting tool.

[90] Rotary surgical cutting tools, powered handpieces, and resultant surgical cutting systems of the present disclosure provide marked improvements over previous designs. By providing a self-energizing latch, the surgical cutting tools are highly convenient, capable of quick assembly and locked engagement to the powered handpiece in an intuitive manner. Optional powered handpieces of the present disclosure can be configured to interface with the surgical cutting tool in a similar fashion, and optionally provide mechanisms for quick release the surgical cutting tool.

[91] Although the present disclosure has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the present disclosure. For example, while the self-energizing latch has been described as being provided with the surgical cutting tool and static bearing surfaces included with the powered handpiece for interfacing with the self- energizing latch, in other embodiments, the self-energizing latch can be a component of the powered handpiece (with the surgical cutting tool forming or including corresponding features or surfaces for interfacing with the latch in a desired manner). In other embodiments, the latch provided with the surgical cutting tool can be configured to self-expand toward a normal state upon insertion into the powered handpiece (and in particular upon interfacing with features provided with the handpiece) to achieve the locked arrangement.

Claims

What is claimed is:

1. A surgical cutting tool adapted to be rotatably driven by a motor, the surgical cutting tool comprising:

an elongated shaft defining a proximal region and a distal region;

a cutting head carried by the distal region; and

a self-energizing latch carried by the proximal region;

wherein the latch is configured to provide a first, normal state and is further configured to self-transition from a second, deflected state toward the first, normal state;

and further wherein a maximum outer dimension of the latch in the first, normal state differs from a maximum outer dimension in the second, deflected state.

2. The surgical cutting tool of claim 1, wherein the self-energizing latch is configured to expand in self-transitioning from the second, deflected state toward the first, normal state.

3. The surgical cutting tool of claim 1, wherein the elongated shaft defines a central axis, and further wherein the maximum outer dimension is perpendicular to the central axis.

4. The surgical cutting tool of claim 1, wherein the self-energizing latch is co-axially disposed over the proximal region.

5. The surgical cutting tool of claim 4, wherein the proximal region terminates at a proximal end of the tool, and further wherein the self-energizing latch is arranged immediately adjacent the proximal end.

6. The surgical cutting tool of claim 5, wherein the maximum outer dimension of the self-energizing latch in the first, normal state in a direction perpendicular to a central axis of the shaft is larger than a diameter of the proximal end.

7. The surgical cutting tool of claim 5, wherein the proximal region defines a capture segment and a drive segment, and further wherein the self-energizing latch is disposed over the capture segment, and even further wherein an outer surface of the drive segment is configured for selective coupling with a drive chuck.

8. The surgical cutting tool of claim 7, wherein the outer surface is hexagonal in transverse cross-section.

9. The surgical cutting tool of claim 1, wherein the self-energizing latch is configured to selectively couple with a shoulder formed by a powered handpiece.

10. The surgical cutting tool of claim 1, wherein the self-energizing latch includes a C-shaped clip.

11. The surgical cutting tool of claim 1, wherein the self-energizing latch includes a spring finger.

12. The surgical cutting tool of claim 11, wherein the spring finger includes a base opposite a tip, and further wherein the base is connected to the shaft and the tip is biased away from the shaft in the first, normal state.

13. The surgical cutting tool of claim 12, wherein the tip is disposed proximate the shaft in the second, deflected state.

14. The surgical cutting tool of claim 1, wherein the self-energizing latch includes a ring defining a central section and opposing end sections, and further wherein the central section has a diameter greater than a diameter of either of the end sections in the first, normal state.

15. A surgical system for cutting tissue, the system comprising: a powered handpiece including:

a housing,

a drive shaft rotatably maintained by the housing, a coupling assembly disposed within the housing and including a drive chuck connected to the drive shaft; and

a surgical cutting tool releasably connectable to the powered handpiece, the surgical cutting tool including:

an elongated shaft defining a proximal region and a distal region, a cutting head carried by the distal region,

a self-energizing latch carried by the proximal region, wherein the latch is configured to provide a first, normal state and is further configured to self-transition from a second, deflected state toward the first, normal state,

and further wherein an maximum outer dimension of the latch in the first, normal state is different from the maximum outer dimension in the second, deflected state;

wherein the system is configured such that upon initial insertion of the proximal portion into the housing, the self-energizing latch is forced from the first, normal state to the second, deflected state and with further insertion, the self-energizing latch self-transitions toward the first, normal state for locked interface with the coupling assembly.

16. The system of claim 15, wherein the coupling assembly is configured to engage the self-energizing latch in the first, normal state.

17. The system of claim 15, wherein the coupling assembly includes a bearing surface for biasing the self-energizing latch from the first, normal state to the second, deflected state.

18. The system of claim 15, wherein the drive chuck defines a central passage for receiving the proximal region and a capture chamber configured to maintain the self-energizing latch in the first, normal state.

19. The system of claim 18, wherein the proximal region of the elongated shaft includes a drive segment and a capture segment, the self-energizing latch being disposed over the capture segment, and further wherein an interior portion of the drive chuck and the drive segment of the elongated shaft have a complimentary shape for rotational interface.

20. The system of claim 15, wherein the handpiece further includes an actuator assembly associated with the coupling assembly, the actuator assembly configured to selective articulate the self-energizing latch from the first, normal state to the second, deflected state in the loaded condition