Computer-aided surgery apparatus - Patent Review 5305203

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BACKGROUND OF INVENTION

1. Field of the Invention

The invention relates to a computer-aided surgery apparatus. More specifically, the invention relates to such an apparatus which aids a surgeon in accurately positioning surgical instruments for performing surgical procedures on a patient.

The invention also relates to a linkage mechanism for connecting a fixed point on a portion of interest of a patient (for example, a fixed point on a leg or arm of a patient) with a fixed point on the apparatus, and for maintaining a fixed separation between the fixed points, whereby, to maintain a fixed relationship between the portion of interest of the patient and the apparatus even when the portion of interest of the patient is being moved.

2. Description of Prior Art

Many surgical procedures, particularly in the fields of orthopedic surgery and neurosurgery, involve the careful placement and manipulation of probes, cutting tools, drills and saws amongst a variety of surgical instruments.

There are available mechanical apparatus which are used for different surgical procedures to help the surgeon guide the surgical instruments to ensure proper alignment. These alignment mechanisms must be referenced to certain anatomical landmarks and the set-up time for the various alignment jigs can represent a significant portion of the total surgical duration.

When surgical procedures are required on, for example, unexposed tumors or the like, fluroscopy is used to indicate to the surgeon the position and orientation of the surgical procedure. This has the disadvantage of exposing a patient and physician to radiation. In addition, the accuracy is less than adequate for precision requirements of the surgery.

In addition, in procedures relating to the cutting of boney parts for the purposes of joint replacement, fracture repair or deformity correction, among others, there is the problem of tool orientation such as drilling from point to point, sawing, locating planes in specific orientations with other planes of specific orientations, etc. The problems of 3-dimensional control of the surgical instruments becomes formidable. As above mentioned, some jigs exist for the performance of limited procedures permitting safe and reproducible orientation of tools. However, these have the disadvantage of being less than adaptable to variations that occur during surgical procedures. In addition, the limits of inaccuracy permissible for satisfactory results during surgery leave many of the currently accepted techniques for surgical instrument control unacceptable.

Although the field of 3-dimensional imaging as represented in the techniques of MRI (magnetic resinence imaging) and CAT scans (computer aided tomography) provide an abundance of 3-dimensional information concerning the locations of, for example, unexposed tumors, there is presently no interface between this information and the surgical processes which provide remedies. Required is an apparatus which can transpose the information of the 3-dimensional imaging systems from the reference system of the 3-dimensional imaging systems to a reference system of the apparatus.

U.S. Pat. No. 4,473,074, Vassiliadis, Sep. 25, 1984, teaches a device providing a laser beam in the performance of microsurgical procedures. The apparatus of the '074 patent does not have the facilities for providing electronic feedback of 3-dimensional information from 3-dimensional imaging systems for the purposes of presentation and feedback to the surgeon to thereby complete a feedback loop necessary to make full use of the instrument in sophisticated procedures. In addition, the device of the '074 patent can be used only to direct a laser beam at an exposed target, so that it is not applicable for surgical procedures on unexposed portions of a patient.

SUMMARY OF INVENTION

It is therefore an object of the invention to provide a computer-aided surgery apparatus which provides significant improvements over present technologies for aiding a surgeon in accurately positioning surgical instruments for performing surgical procedures on a patient such as hole drilling, bone sawing, distance measurement and site location (e.g. point to point distance, blind hole location), and stereotaxic aiming and locating.

It is a more specific object of the invention to provide such an apparatus which includes a computer driven precision instrumented linkage attached to a surgical instrument and providing the surgeon with instantaneous and continuous feedback on 3-dimensional orientation of the tool.

It is a still further object of the invention to provide such a linkage which can also be used as an independent anatomical point digitizer so that important reference landmarks can be located and subsequently used as points of reference for surgery.

It is a still further object of the invention to provide an apparatus which eliminates time-consuming set-up of jigs and other apparatus for guiding the surgical instruments and which apparatus is really an intelligent jig capable of adapting to the vageries and unexpected developments often confronted during surgery.

In accordance with the invention, there is provided a computer-aided surgical device for aiding a surgeon in positioning a surgical instrument (power or manual) when performing surgery on unexposed and exposed portions of a patient.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be better understood by an examination of the following description, together with the accompanying drawings, in which:

FIG. 1 is a 3-dimensional view of the apparatus in relationship to a patient on an operating table;

FIG. 2 illustrates the rolling upright stand, the monitor and the electrogoniometer;

FIG. 3 illustrates one means for connecting surgical instruments to the electrogoniometer;

FIG. 4 is a more detailed view of the reference block;

FIGS. 5, 6, 7 and 8 illustrate how the Double Self Indexing Screw (DSIS) is attached to a bone of a patient;

FIG. 8A illustrates an alternative to the DSIS;

FIG. 9 illustrates the first link to the DSIS;

FIG. 10 illustrates the complete link between the DSIS and the reference block of the apparatus;

FIG. 11 is a cross-section through XI--XI of FIG. 9 (with the shaft removed);

FIG. 12 is a cross-section through XII--XII of FIG. 9 (with the shaft removed);

FIGS. 13 and 14 are examples of screen displays to aid in drilling procedures;

FIGS. 15 and 16 are examples of screen displays to aid in sawing procedures;

FIGS. 17 and 18 are examples of screen displays to aid in spinal curvature measurement procedures; and

FIG. 19 is a screen display to aid in an implant placement procedure.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, the apparatus in accordance with the invention, illustrated generally at 1, is disposed for operation on a patient 3 lying on an operating table 5. The apparatus includes an electrogoniometer 7 which is preferably of the type described in my U.S. Pat. No. 4,571,834. The six degree of freedom electrogoniometer is designed to provide easy access to any part of the patient in the surgical venue. Surgical instruments are connected to the free end 7a of the electrogoniometer. The other end of the electrogoniometer is connected to a reference block 9 which will be more fully discussed below.

In order to permit movement of the electrogoniometer and reference block to different positions along the patient, the reference block and electrogoniometer are connected to a swinging balanced arm 11. The other end of the balanced arm is connected to an upright post 13 of a rolling upright stand 15. The upright post 13 also supports a monitor support arm 17 which carries a monitor, preferably a colour monitor, 19.

The swinging balanced arm 11 may consist of two portions, 10 and 12, which are pivotal relative to each other, and the portion 10 is pivotal relative to the upright post 13. In a like manner, monitor support arm 17 is pivotal relative to the upright post 13 so that its position can be altered for better viewing by the surgeon.

Foot pedal switch 21 is provided for controlling the displays on the monitor 19, and remote computer 23 performs computations for providing the displays on the monitor.

Turning to FIG. 2, the rolling upright stand 15 comprises rollers 25 to roll the apparatus into different positions alongside the operating table. The electrogoniometer and the swinging balanced arm are covered by a tubular sterile barrier 27 to maintain the integrity of the sterile field around the patient. Instruments which are attached to end 7a of the electrogoniometer are sterilizable in an autoclave to further maintain the integrity of the sterile field.

One mechanism for attaching the surgical instrument to the end 7a of the electrogoniometer is illustrated in FIG. 3. As can be seen, this constitutes a V block 29 disposed within the tubular sterile barrier 27. The instrument itself includes a mating V block 31, and the protruding V of 31 is inserted into the indented V of 29. A pin, such as 32, extends through aligned openings in both 29 and 31. This type of connecting mechanism ensures that the position and orientation of the instrument relative to the electrogoniometer is fixed during the entire surgical procedure.

Turning now to FIG. 4, the reference block includes a reference backplate 33, reference top surfaces 35, reference holes 37 and a V-groove drill reference 39. The purpose of these elements of the reference block, as will be seen below, is to determine the position, orientation and length of various ones of the surgical instruments, as well as the security of the installation of the instruments.

It is also seen in FIG. 4 that the reference block is connected to swinging balanced arm 11 by a ball support 41 which includes an internal ball joint so that spherical motion of the reference block relative to the arm 11 is possible.

From a review of the above-referenced U.S. Pat. No. 4,571,834, it will be clear that the position 7a of the electrogoniometer relative to the reference block (or perhaps more accurately a point on the reference block) will constantly be calculated by the computer which receives inputs from the transducers connecting the various portions of the electrogoniometer. It will also be apparent that the dimensions of the surgical instrument, especially the location of the operating portion of the surgical instrument relative to the end 7a of the electrogoniometer, will both be known and verified by tests on the reference block as will be described below. Accordingly, the position of the operating portion of the surgical instrument will be constantly calculated by computer 23, as described in U.S. Pat. No. 4,571,834, and this position can therefore be continuously displayed on the monitor 19.

As the position and orientation of the surgical instrument is determined relative to the reference block, it is desirable to maintain a fixed separation and relationship between the portion of the patient on which operating procedures are to be performed and the reference block. As the portion on which surgical procedures are being performed may have to be moved from time to time during these surgical procedures, it is desirable that the means for maintaining the fixed relationship constitute a mechanical linkage whereby, when the portion of the patient is moved, the reference block, and therefore the electrogoniometer, will move with it. For this purpose, there is provided in accordance with an aspect of the invention, a Double Self Indexing Screw and mechanical linkage illustrated in FIGS. 5 to 12. The Double Self Indexing Screw (DSIS) is illustrated in FIGS. 7 and 8 at 42 and includes a cylindrical portion 43 and a top cap portion 44 as well as a bottom central screw 45 and bottom alignment pins 47 and 49. Screw 45 and pins 47 and 49 are in alignment with each other. The procedure for mounting the DSIS on a portion of interest of the patient is illustrated in FIGS. 5 to 8. Turning first to FIG. 5, the DSIS is to be mounted on, for example, a leg 51. The recent advent of surgical techniques employing arthroscopy in order to minimize soft tissue trauma during surgery requires that the DSIS attachment be made through an incision no greater than 20 mm. Such an incision is shown on the leg 51 with a skin flap 53 lifted to expose bone 55. A first hole 57 is drilled, by drill 59, into the bone 55. A drill guide 61, which includes holes 63 and 65 and guide pin 67, 63, 65 and 67 being in alignment, is then manipulated so that pin 67 is inserted into the hole 57. A second hole is then drilled in bone 55 through, for example, hole 65 of drill guide 61. A reference pin 69 (see FIG. 6) is then inserted into the second drilled hole through hole 65 of drill guide 61 as shown in FIG. 6. A third hole is then drilled in the bone through hole 63. As holes 63, 65 and guide pin 67 are in alignment, the drilled holes will be in alignment as shown at 73, 57 and 71 in FIG. 7.

The DSIS is then connected to the bone by inserting screw 45 into hole 57, pin 47 into hole 73 and pin 49 into hole 71. The screw 45 is screwed into hole 57 by rotation of screw handle 75 which rotates only the screw 45. With the DSIS mounted as shown in FIG. 8, the attachment is both firm and the DSIS is, because of the pins 47 and 49 being inserted in holes 73 and 71 respectively, restrained from rotary motion about its own longitudinal axis.

At times, it may be inconvenient or undersirable to drill holes 71 and 73 for the purpose of mounting the DSIS. Accordingly, an alternative means is provided to replace the DSIS. Specifically, a saw-tooth self-indexing screw is provided.

Referring to FIG. 8A, it can be seen that the alignment pins 47 and 49 have been eliminated and that the bottom end of the cylindrical portion 43 includes a saw-tooth arrangement 150. Cylindrical portion 143 is shown bent in FIG. 8A, although it could be straight as cylindrical portion 43 is shown in FIG. 8. The bent portion of 143 includes an opening 147 through which screw 145 is passed. Accordingly, when screw 45 is screwed into a hole such as 57 in FIG. 7, the saw-tooth will be embedded in the surrounding bone so that the self-indexing screw will once again be restrained from rotary motion about its longitudinal axis.

The first link from the DSIS to the reference block is illustrated in FIG. 9 and comprises a linear spherical DSIS clamp illustrated generally at 77. The DSIS clamp 77 includes a ball joint arrangement 79 and a clamping member 81.

As seen in FIG. 10, the complete link includes a plurality of clamping members 81 interconnected by shafts 85. Each clamping member includes at least one through hole 83 to receive a shaft 85. The clamping members may also include two transverse through holes 83 as shown at 81a. In addition, the clamping members may also be adapted to receive a shaft at the bottom end thereof as shown in 81b. Each clamping member 81 includes a handle 87, and shaft 85b is insertable into an opening of T member 87 mounted on reference block 9.

Referring now to FIG. 11, clamping member 81 includes a screw 89 which is rotatable by handle 87 to move the screw upwardly or downwardly in the interior of the clamping member. Movement of the screw will cause similar movement of V block 91 which is disposed in opposition to V block 93 in the interior of the clamping member 81. With the V blocks 91 and 93 as illustrated in FIG. 11, the cross-sectional shapes of the shafts 85 would be diamond shaped so that, when screw 89 is tightened, the shaft will be firmly grasped between V blocks 91 and 93. Obviously, shafts with different cross-sectional shapes could be used whereupon the shapes of blocks 91 and 93 would be appropriately altered.

Referring to FIG. 12, the ball joint arrangement 79 includes a spherical ball bearing joint having a split outer race 95. The head 44 of the DSOS 43 (see FIGS. 7 and 8) is inserted into opening 80 (see FIG. 9) of ball joint arrangement 79. The spherical ball joint permits spherical rotation of the DSOS 43 relative to the ball joint arrangement 79. When handle 87 is rotated to move screw 89 downwardly, downward pressure will also be applied against block 93 to thereby close the split O-ring 95. Accordingly, the head 44 of the DSOS 43 will be firmly grasped in ball joint arrangement 79.

With the linkage arrangement as illustrated in FIG. 10, there is therefore a fixed and firm relationship between a point on the patient's, for example, leg and the reference block 9. Any motion which is imparted to the leg will therefore also be imparted to the reference block. Thus, for example, if the surgeon should lift the leg while drilling a hole or sawing a plane on the knee, the orientation of the reference plane with respect to the bone will not be disturbed since the reference plane is freely following that bone during this minimum motion. Thus, the surgeon will be able to carry on surgical procedures in his normal customary fashion without disturbing the accuracy or verity of the apparatus.

The apparatus is menu driven and the operation of the apparatus will be described in terms of various menus which are given as examples of how the apparatus may be used.

The Main Menu, illustrated in Table 1 below, is divided into four main categories: Drilling Menu; Sawing Menu; Measurement Menu; Stereotaxic Misc. Menu.

TABLE 1 ______________________________________ MAIN MENU ______________________________________ *1 Drilling Menu 2 Sawing Menu 3 Measurement Menu 4 Stereotaxic Misc. Menu 5 Return to Master Menu ______________________________________

The menu selections are made by depressing the right pedal of the foot switch 21, depressing the left pedal to confirm. Each time the right pedal is pressed, the pointer will move down one space. When the pointer is adjacent the required menu, then the left pedal is pressed. Selection of an item, for example, the Drill Menu, will result in the presentation of the Drill Menu.

Considering now the Drill Menu, illustrated in Table 2 below, the performance of drilling operations involves four basic steps, namely, digitizing the entry/exit points, installing the drill, installing the drill bit, and drilling the hole. In steps 2 and 3, the configuration, alignment and size of the drill and drill bit are defined.

TABLE 2 ______________________________________ DRILL MENU ______________________________________ *1 Digitize Entry/Exit Points 2 Install Drill 3 Install Drill Bit 4 Drill Hole 5 Return to Main Menu ______________________________________

To perform the digitization step (step 1) a digitization tip is installed at end 7a of the electrogoniometer. The digitization tip is then calibrated by inserting it into holes 37 of the reference block to verify the axis (orientation) of the digitization tip. It is noted that it is inserted into two holes so that the reproducibility is also confirmed.

The desired entry point is then digitized by placing the end of the digitizer tip at the desired entry position. The desired exit point is similarly digitized.

The end 7a of the electrogoniometer can, of course, accept a variety of different surgical instruments including different drilling instruments. A selected drilling tool is mounted at 7a. A reference pin is then mounted in the drill bit and inserted into holes 37 of the reference block 9. Once again, this verifies the axis (orientation) as well as the security of the installation of the drill mounting on the electrogoniometer. When the axis of the drill has been determined, the reference pin is replaced with the desired drill bit, and the drill bit is then placed in the groove 39 of reference block 9 with the free end of the drill bit up against backstop 33 of the reference block whereby to determine the orientation and length of the drill bit.

When item 4 of Table 2 is sele