Surgical attachment instrument and method

A surgical attachment instrument and method according to which a housing is adapted to be coupled to a motor. A tubular member is coupled to the housing so that an end of the tubular member extends from the housing at a predetermined distance. The predetermined distance may be selectively adjusted by a repeatable increment.

FIELD OF THE INVENTION

The present invention relates generally to surgical instruments and in particular to surgical instruments for dissecting bone and other tissue.

BACKGROUND

During various surgical procedures, it is necessary to dissect bone or other tissue. Many conventional surgical instruments used for the dissection of bone or other tissue employ pneumatic or electrical motors to rotate a cutting element. In their most basic form, such surgical instruments typically include a motor having a rotary shaft, a dissection tool having a cutting or abrading element that is moved by the rotating shaft of the motor, and a coupling arrangement for connecting the dissection tool to the rotary shaft. The dissection tool often has a small shaft diameter in relation to its length. The shaft may bend or flail in use if not adequately supported or protected. The risk of bending is heightened when the shaft is used with a motor that is designed to reach speeds in excess of 72,000 rpm.

To support and/or protect a dissection-tool shaft, an attachment or tube may be provided that engages the motor and receives a portion of the dissection-tool shaft. Some attachments or tubes may remain stationary relative to the motor. An example of a stationary attachment is disclosed in detail in co-pending patent application Ser. No. 10/200,683, filed Jul. 22, 2002, the disclosure of which is incorporated by reference.

Other attachments or tubes may move axially or telescope relative to the motor, thereby allowing the surgeon to vary the distance that the distal end of the tube extends from the motor, and hence vary the distance that the distal end of the dissection-tool shaft extends from the distal end of the tube. Thus, the portion of the dissection-tool shaft received and supported and/or protected by the tube may be varied as desired or needed. For example, a decrease in the portion of the dissecting-tool shaft received by the tube may be required to accommodate spatial constraints associated with the surgical area. An example of a telescoping attachment is disclosed in detail in co-pending patent application Ser. No. 10/326,178, filed Dec. 20, 2002, the disclosure of which is incorporated by reference.

However, problems may arise during the operation of a surgical instrument having a typical attachment or tube. For example, the stiffness of the tube may not be sufficient to provide adequate stability to the cutting or abrading element, especially in light of the dissection-tool shaft being subjected to various static and/or dynamic loads during normal dissection operation. Also, due in part to vibration, any threadably engaged components of the attachment may disengage from each other during normal dissection operation.

In addition to the foregoing, for telescoping attachments, many configurations require one or more components to be added to the attachment to provide the telescoping functionality. These components may interfere with the surgeon's line of sight to the surgical area during the dissection operation. Also, it may be difficult for the surgeon to telescope the attachment in an incremental and repeatable manner.

Therefore, what is needed is a surgical attachment instrument that overcomes one or more of the above-described problems.

All patent publications listed in Table 1 are hereby incorporated by reference herein in their respective entireties. As those of ordinary skill in the art will appreciate readily upon reading the Summary of the Invention, Detailed Description of the Preferred Embodiments and Claims set forth below, many of the devices and methods disclosed in the patent publications of Table 1 may be modified advantageously by using the teachings of the present invention.

SUMMARY OF THE INVENTION

In one embodiment, a surgical attachment instrument includes a housing adapted to be coupled to a motor. A tubular member is coupled to and extends from the housing at a predetermined distance. The predetermined distance may be adjusted in repeatable increments so that the tubular member telescopes relative to the housing in an incremental and repeatable manner. Further, the tubular member may be locked so that longitudinal movement of the tubular member relative to the housing is prevented. Means for adjusting and locking the tubular member are provided without appreciably increasing the surgical attachment instrument's interference with the surgeon's line of sight to the surgical area.

Further, a coupling connects the tubular member and the housing, and an arcuate member is concentrically disposed between the coupling and the housing. At least a portion of the arcuate member extends in a channel formed in the housing to resist disengagement of the coupling from the housing during operation of the surgical attachment instrument. Still further, the tubular member extends around at least two adjacent bearing assemblies that support a shaft adapted to be coupled to the motor. A spacer extends between the two adjacent bearing assemblies and is lockingly engaged with the tubular member to stabilize the shaft.

Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It is understood that various embodiments of the present invention may overcome one or more of the above-described problems. It is further understood that the detailed description is intended for the purpose of illustration only and is not intended to limit the scope of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIG. 1, the reference numeral10refers, in general, to a dissection tool assembly used to dissect human bone or other tissue. For example and as shown, the dissection tool assembly10may be used during a neurological operation on a human patient A to dissect a portion of the patient's bone or other tissue B in order to provide access to the brain or other neurological structures.

Referring toFIG. 2, the dissection tool assembly10includes a surgical attachment instrument12having an attachment housing14. A pneumatic motor16having a distal portion16ais coupled to a cavity portion14aformed in the housing14so that the distal portion is disposed in the cavity portion. The motor16is connected to a hose assembly18that supplies pressurized air to the motor and vents low-pressure exhaust air away from the surgical area. The motor16, the hose assembly18and the coupling of the motor16to the housing14are disclosed in detail in co-pending patent application Ser. No. 10/200,683, filed Jul. 22, 2002, the disclosure of which is incorporated by reference.

A dissection tool20includes a shaft22and a surgical element such as a dissection head24connected to the distal end of the shaft. The shaft22is disposed through the surgical attachment instrument12, and is inserted in and coupled to the distal portion16aof the motor16. This coupling of the shaft22to the motor16is disclosed in detail in the above-incorporated patent application.

Referring toFIGS. 3 through 5D, the surgical attachment instrument12further includes a coupling26having an external threaded portion26aand a circumferentially-extending channel26bformed in the coupling adjacent to the threaded portion. A protrusion26cextends out of the channel26b. A ring26dextends around the coupling26and is disposed adjacent to the channel26b. Opposing through-openings26eand26fare formed in the channel26b. A groove26gis formed in the proximal end portion of the coupling26and a pair of markings26hand26iare printed or formed near the distal end of the coupling, the marking26hindicating a “locked” position and the marking26iindicating an “unlocked” position, as will be further described. A bore26jlongitudinally extends through the coupling26.

A tubular member28includes a bore28aand a plurality of grooves28bformed in the wall of the bore at the proximal end of the tubular member. Transverse index markings29athrough29eare printed or formed in the tubular member28. Arrow markings30athrough30care also printed or formed in the tubular member28perpendicular to and through the index markings29athrough29e. A plurality of crimps31a,31band31care formed in the tubular member28so that each crimp includes a protrusion portion extending from the inner wall of the tubular member28. A plurality of transversely-extending locking channels32a,32b,32c,32dand32eare formed in the proximal end portion of the tubular member28. The longitudinal (or axial) spacing between the channels32aand32b,32band32c,32cand32d, and32dand32eare substantially equal and correspond to the spacing between the index marks29aand29b,29band29c,29cand29d, and29dand29e, respectively.

As more clearly shown inFIG. 4, locking detents34athrough34eare formed in the tubular member28at the ends of the channels32athrough32e, respectively. Likewise, positioning detents36athrough36eare formed in the tubular member28at the opposing ends of the channels32athrough32e, respectively. The depth of each detent34athrough34e, and each detent36athrough36e, is greater than the depth of each channel32athrough32e, respectively. A longitudinally-extending positioning channel38is formed in the proximal end portion of the tubular member28and extends from the detent36ato the detent36e, passing through the detents36bthrough36d. The channel38is not continuous, but instead is interrupted by the detents36athrough36ebecause the depth of the channel is less than the depth of each detent36athrough36e.

The foregoing arrangement of the channels32athrough32e, the detents34athrough34e, the detents36athrough36eand the channel38is replicated on the surface of the tubular member28opposite the surface shown inFIGS. 3 and 4so that, if the tubular member28shown inFIG. 4was rotated 180 degrees, the view with respect to these replicated channels and detents would be identical to that ofFIG. 4. These replicated channels and detents are referred to by corresponding prime reference numerals (the detents34a′,34b′,34c′,34d′ and34e′ are shown inFIG. 5B).

Bearing assemblies40a,40b,40cand40dare disposed in the bore28aof the tubular member28. Spacers42a,42band42care also disposed in the bore28aso that the spacer42ais positioned between the bearing assemblies40aand40b, the spacer42bis positioned between the bearing assemblies40band40c, and the spacer42cis positioned between the bearing assemblies40cand40d. Channels42a′,42b′ and42c′ are formed in the spacers42a,42band42c, respectively. As clearly shown inFIG. 5C, the spacers42athrough42care positioned in the bore28aso that the protrusion portions of the crimps31a,31band31cextend into the channels42a′,42b′ and42c′, respectively, and lockingly engage the spacers.

A stop44is connected to the distal end of the tubular member28and a portion of the stop is positioned in the bore28a. A plug46having a pair of channels46aand46bis positioned in the bore28anear the proximal end of the tubular member28so that the channels are associated the grooves28b. The plug46applies a force against the bearing assembly40aand is positioned in the bore28aso that, due to the fixed position of the stop44, clamping forces are applied to the bearing assemblies40athrough40dand the spacers42athrough42c. The channels46aand46band the grooves28bare filled with an adhesive such as epoxy so that the plug46is fixed within the bore28a, thereby maintaining the aforementioned clamping forces. The plug46, the bearing assemblies40athrough40d, the spacers42athrough42cand the stop44form a substantially continuous bore48(shown inFIG. 5B).

A bore50of varying cross-section extends through the housing14, from the cavity portion14aand to the distal end of the housing. Balls52aand52bare received by the openings26eand26f, respectively. A keeper spring54is disposed in the channel26bof the coupling26and in a channel50aformed in the inner wall of the bore50, contacting and applying inwardly-directed radial forces on the balls52aand52b. An arcuate member56partially extends about the proximal end portion of the coupling26. The arcuate member56includes a tab56athat is disposed in the groove26g.

When the dissection tool assembly10is in its assembled condition shown inFIGS. 5A through 5D, the coupling26is disposed in the bore50and is threadably engaged with the housing14via the threaded portion26aso that the distal end of the housing is adjacent to or abuts the ring26d. The outer surfaces of the housing14and the ring26dare substantially flush. It is understood that an adhesive such as epoxy may be applied to the threaded portion16a. The tubular member28is slidably engaged with the coupling26so that the balls52aand52bare seated in the opposing detents34eand34e′, respectively, and the distal end of the tubular member28extends from the housing14at a predetermined distance. The outer diameter of the coupling26decreases from the ring26dto the distal end of the coupling so that, at the distal end, the difference between the outer diameters of the coupling and the tubular member28is relatively small.

The shaft22of the dissection tool20extends through the bore48and, as discussed above, is inserted in the distal portion16aof the motor16which, in turn, is positioned within the cavity portion14aof the housing14(motor not shown). The dissection head24and the distal portion of the shaft22extend out from the tubular member28. The tubular member28is in a “locked” position, as indicated by the alignment of the arrow marking30cwith the marking26hshown inFIG. 5A, because the tubular member28is unable to move relative to the coupling26, as will be further described in detail below.

In operation, the motor16receives high-pressure air via the hose assembly18to rotate a rotor shaft (not shown in the Figures) that is coupled with the shaft22of the dissection tool20, as disclosed in detail in the above-incorporated patent application. Due to this coupling, the shaft22rotates, thereby rotating the dissection head24, which may be applied against bone or other human tissue to cut or dissect the bone or tissue. Low-pressure exhaust air exits the motor16through an exhaust passage in the hose assembly18.

During this time, the dissection tool assembly10is in its assembled condition described above and the shaft22rotates in the bores48and50. The bearing assemblies40athrough40dsupport the rotating shaft22. Due to the above-described clamping forces, the spacers42a,42band42climit any movement of the bearing assemblies40athrough40drelative to the bore28bof the tubular member28, providing increased stability to the shaft22.

The locking engagement of the crimps31a,31band31cwith the channels42a′,42b′ and42c′, respectively, facilitates the binding of the wall of the bore28bto the spacers42a,42band42c, respectively, thereby limiting any movement of the spacers relative to the bore28b. This serves to better stabilize the shaft22while the dissection head24is dissecting the bone or tissue, during which time the dissection tool assembly10is subjected to a variety of static and/or dynamic (shock or vibrating) loads in a variety of directions. The binding of the wall of the bore28bto the spacers42athrough42calso increases the stiffness of the tubular member28, providing increased stability to the shaft22, especially when the coupling26or the tubular member28is subjected to static or dynamic transverse loading.

The adhesive applied to the threaded portion26aprevents the coupling26from disengaging from the housing14while the dissection tool assembly10is undergoing the above-described static and dynamic loading. The arcuate member56secondarily prevents the coupling26from disengaging from the housing14, as will be further described in detail below.

As noted above and during operation, the tubular member28is in a “locked” position where the tubular member28is unable to move in a longitudinal direction relative to the coupling26, the housing14and the tool20. It is understood that a “locked” position during operation of the dissection tool assembly10is desirable in order to prevent any unwanted axial movement of the tubular member28, relative to the coupling26and the shaft22, that might interfere with the surgeon's line of sight or the cutting operation of the dissection head24, thereby possibly increasing the risk of harm to the human patient.

As shown inFIGS. 5B and 5D, the tubular member28is prevented from moving longitudinally relative to the coupling26because the balls52aand52bare seated in the detents34eand34e′, respectively. If the surgeon attempts to move the tubular member28in a direction towards the dissection head24, the tubular member28will remain substantially in position due to the contact between the walls of the detents34eand34e′ and the substantially immobile balls52aand52bextending through the through-openings26eand26f, respectively. It is understood that the tubular member28is prevented from moving relative to the coupling26when the ball52ais seated in any one of the detents34athrough34e, and the ball52bis seated in any one of the detents34a′ through34e′.

The keeper spring54prevents the balls52aand52bfrom falling out of the through-openings26eand26f, respectively. The keeper spring54holds the balls52aand52bin place due to the spring's application of inwardly-directed radial forces on the balls. The protrusion26climits the rotation of the keeper spring54about the coupling26in the channel26bto the extent that the location of the split in the keeper spring54does not correspond to the location of the through-openings26eand26f(split shown inFIG. 3).

As shown inFIGS. 5A and 5B, the distal portion of the shaft22is exposed to view, extending out from the tubular member28as far as possible while remaining in a “locked” position as described above. The alignment of the distal end of the coupling26with the index marking29efurther indicates this condition of maximum shaft22extension and the corresponding maximum insertion of the tubular member28into the coupling26. In order for the tubular member28to protect and/or support a greater amount of the distal portion of the shaft22, the tubular member is moved axially in a direction towards the dissection head24, relative to the coupling26, the housing14and the tool20.

To so move the tubular member28, the motor16is adjusted so that the shaft22of the tool20ceases to rotate. The tubular member28is then rotated counterclockwise (as viewed inFIGS. 3 and 4) about its longitudinal axis while the coupling26remains stationary. Rotation of the tubular member28results in the rotation of the channel32e(FIG. 5D) towards the ball52a. The difference between the depths of the detent34eand the channel32eis sized so that the channel32eis able to slide underneath the ball52a. The keeper spring54resists the sliding of the channel32eand the corresponding outwardly-directed radial movement of the ball52a, providing tactile and/or acoustic feedback to the surgeon that indicates that the channel is indeed underneath the ball52a. It is understood that the operation of the tubular member28with respect to the ball52b, and the corresponding channels and detents referred to by prime reference numerals, is identical to the foregoing, and is also identical to the below-described operation with respect to the ball52a, and therefore will not be described.

Referring toFIGS. 6A through 6C, rotation of the tubular member28is continued so that the channel32econtinues to slide against the ball52auntil the ball52afalls into the detent36e, assisted by the force applied on the ball by the keeper spring54. The falling of the ball52afrom the channel32eand into the detent36e, and the corresponding decrease in loading on the keeper spring54, provides both acoustic and tactile feedback to the surgeon, indicating that the ball is indeed in the detent36eand in an “unlocked” position. The alignment of the arrow30cwith the marking26iprovides further confirmation of this “unlocked” position. The contact between the ball52aand the wall of the detent36eprevents the tubular member28from further counterclockwise rotation.

A longitudinally-directed force is applied to the tubular member28so that the tubular member is moved axially in the direction towards the dissection head24, during which time the channel38slides along underneath the ball52a. As the detents34d,34cand34balso slide underneath the ball52aduring this movement, the ball drops down into each detent, providing acoustic and tactile feedback to the surgeon as to the extent of the tubular member28's movement. The movement of the index markings29athrough29erelative to the coupling26further indicates the extent of the tubular member28's movement. The tubular member28continues to be moved axially until the detent36aslides underneath the ball52aand the ball drops into the detent. Contact between the ball52aand the wall of the detent36aprevents further axial movement of the tubular member28in the direction towards the dissection head24.

The tubular member28is placed in a “locked” position by rotating the tubular member28in a clockwise direction (as viewed inFIGS. 3 and 4). During this rotation and referring toFIGS. 7A through 7C, the detent34arotates towards the ball52awhile the channel32aslides underneath the ball. The ball52afalls into the detent34a, providing acoustic and tactile feedback to the surgeon, indicating that the ball is indeed in the detent34aand in a “locked” position. At this point, the tubular member28protects and/or supports the greatest amount of the distal portion of the shaft22while still being in a “locked” position, as indicated by the alignment of the distal end of the coupling26with the index marking29a, and the alignment of the arrow30awith the marking26h. Normal operation of the motor16, and the corresponding rotation of the shaft22and the dissection head24, may now resume.

Instead of axially moving the tubular member28until the ball52afalls into the detent36a, it is understood that the movement of the tubular member28may be stopped at any point along the channel38. If the tubular member28movement is stopped when the ball52ais located in the detents36b,36cand36d, the acoustic and tactile feedback of the ball52afalling into any one of these detents indicates to the surgeon that the tubular member28may be locked with respect to its current position relative to the coupling26and the shaft22. The alignment of one of the index markings29athrough29ewith the distal end of the coupling26further indicates to the surgeon that the tubular member28may be placed in a “locked” position. Regardless of which detent36athrough36ethe ball52ais seated in, the procedure for locking the tubular member28is identical to the above-described procedure. Further, rotation of the shaft22and the dissection head24may safely resume as long as the tubular member28is locked, that is, the ball52ais seated in one of the detents34athrough34e.

It is understood that the tubular member28may be unlocked in the above-described manner, moved axially in either direction with respect to the coupling26, and then locked in the above-described manner. Thus, the tubular member28may be selectively adjusted so that it telescopes in and out of the coupling26, towards and away from the dissection head24in discrete, repeatable, and indexed increments. Further, this selective adjustment may be carried out without an appreciable increase in the surgical attachment instrument12's interference with the surgeon's line of sight to the surgical area. This lack of interference is due in part to the outer surfaces of the housing14and the ring26dbeing substantially flush, and the decrease in the outer diameter of the coupling26from the ring to the distal end of the coupling. This lack of interference is further due in part to the positioning of the balls52aand52band the keeper spring54within the housing14.

As noted above, the arcuate member56prevents the threaded portion26aof the coupling26from disengaging from the housing14. Referring toFIGS. 8A through 9B, with continuing reference toFIG. 3, a recess58having walls58aand58bis formed in the wall of the bore50, and a recess60is formed in a wall58bof the recess58. The recess60includes two walls60aand60band a channel62is formed in the wall60b. When the dissection tool assembly10is in its assembled condition, the edge of the arcuate member56opposing the tab56ais contacting the wall60a. A portion of the arcuate member56is crumpled and extends into the channel62formed in the wall60b(most clearly shown inFIG. 9B). It is understood that the material of the arcuate member56is softer than the material of the coupling26and the housing14.

In operation, the arcuate member56initially has an L-shaped cross-section, before the coupling26is fully engaged with the housing14, as shown inFIG. 9A. During assembly, as the coupling26is threadably engaged with the housing14via the threaded portion26a, the proximal end of the coupling26moves axially towards the wall58aand the arcuate member56moves towards and engages the wall60a. The threaded engagement of the coupling26with the housing14is continued so that the proximal end of the coupling26continues to move towards the wall58a. Due to the interfering engagement between the arcuate member56and the wall60a, a portion of the arcuate member crumples and is forced upwards into the channel62, as shown inFIG. 9B. During the normal operation of the dissection tool assembly10, the threaded portion26aof the coupling26is prevented from disengaging from the housing14due in part to the contact between the crumpled portion of the arcuate member56and the walls of the channel62.

During disassembly, a predetermined amount of torque applied to the coupling26will either break or severely damage the arcuate member56so that the coupling may be disengaged from the housing14. The partial circumferential extension of the arcuate member56enables the arcuate member to be easily removed from the coupling26and/or the channel62. The broken or damaged arcuate member56may be discarded and a new arcuate member may be used when re-assembling the coupling26and the housing14.

Variations

It is understood that variations may be made in the foregoing without departing from the scope of the disclosure. These variations include the following:

1. The ball52bmay be removed from the dissection tool assembly10, along with the corresponding channels32a′ through32e′ and38′, and the detents34a′ through34e′ and36a′ through36e′.

2. The number of balls may be increased to three or more, along with a corresponding increase in the channels and detents formed in the tubular member28.

3. The spacers42athrough42cmay be in the form of resilient components such as elastomer or helical springs. For such embodiments, it is understood that the crimps31athrough31cand the corresponding channels42a′ through42c′ may be removed.

4. The position of the plug46in the bore28amay be varied.

5. Instead of using an adhesive in conjunction with the channels46aand46band the grooves28b, the plug46may be connected to the tubular member28by other means such as, for example, with fasteners.

6. In addition to the pneumatic motor16, other types of motors using electricity or other motive forces may be used with the dissection tool assembly10. It is understood that, if other types of motors are employed, the hose assembly18may be removed from the dissection tool assembly10.

7. In addition to the dissection head24, other types of dissection heads may be connected to the distal end of the shaft22. Further, in addition to dissection heads, other types of surgical elements may be connected to the distal end of the shaft22such as, for example, polishing elements.

8. The number of bearing assemblies and spacers in the tubular member28may be varied.

9. The design of the keeper spring54may be modified so that there is one keeper spring engaging each ball52aand52b. Also, the keeper spring54may be in the form of other types of resilient members such as, for example, a helical spring.

10. Any foregoing spatial references, such as “upper,” “between,” “front,” “right side,” “side,” “above,” “beneath,” etc., are for the purpose of illustration only and do not limit the specific spatial orientation of the structure described above.

The preceding specific embodiments are illustrative of the practice of the invention. It is to be understood, therefore, that other expedients known to those skilled in the art or disclosed herein, may be employed without departing from the invention or the scope of the appended claims. For example, the present invention is not limited to instruments and methods for telescoping an attachment tube, stabilizing a rotating shaft in connection with a dissection tool assembly, or connecting different components of a dissection tool assembly. The present invention is also not limited to instruments and associated methods for dissecting bone or other tissue per se, but may find further application in other operations such as, for example, dental procedures. The present invention further includes within its scope the methods of making, assembling and using the dissection tool assembly10described hereinabove.

It is intended that the scope of the disclosure be defined by the claims appended hereto and their equivalents. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts a nail and a screw are equivalent structures.