Patent Application
20050216032
The present invention relates to systems and methods for accurate positioning of tools, fasteners and implants within a patient. More particularly, the invention relates to orthopaedic surgical procedures requiring accurate shaping of the bone or placement of bone engaging elements.
Damage or disease can deteriorate the bones, articular cartilage and ligaments of human joints, such as the knee, which can ultimately affect the ability of the natural joint to function properly. To address these conditions, prosthetic joints have been developed that are mounted to prepared ends of the bones of the joint, namely the tibia and femur in the case of a knee prosthesis.
The implant components define interior mounting surfaces that often require involved cuts into the bone, such as the distal end of the femur or the proximal end of the tibia. The implant components are selected to restore or emulate as much of the natural motion of the knee joint as possible. Consequently, implant positioning with respect to the natural bone is critical. For instance, a proper implant will maintain the proper tension in the retained ligaments supporting the joint.
Preparation of the natural joint to receive a prosthesis must be painstaking to ensure the properly selected implant will work for its intended purpose. For instance, in preparing a knee joint to receive a prosthesis, the orthopaedic surgeon typically uses templates to determine the proper size of the implant components. The surgeon may also measure the joint gap and choose a spacer that can be used in the procedure to maintain that gap. Since the femoral component of the knee prosthesis requires complex cuts in the femur, a femoral resection guide is used, such as the resection guide 10 shown in
While the vertical position of the saw guide slot 14 is adjusted by sliding the adjustment rod 18 relative to the mounting block 16, the angular orientation of the saw guide is determined by the placement of the mounting pins 17 supporting the mounting block. It can be appreciated, then, that the placement of the mounting pins 17 must be as accurate as possible to ensure a proper cut. In order to account for the potential for error in initial placement of the pins, more complex cutting guide assemblies have been developed. These complex devices include multiple degree-of-freedom fine tuning adjustments that can be “dialed in” to optimize the orientation of the saw guide. While accurate bone cuts can be made with these complex devices, they are naturally more expensive and require greater maintenance than cutting blocks as simple as or more simple than the assembly 10 of
Many orthopaedic procedures require performing operations on only partially exposed bones and joints. The use of an imaging modality such as intraoperative x-rays or CT scans can open the surgeon's “field of vision” without requiring greater tissue exposure of the patient. Image guided surgical techniques have been used in orthopaedic surgeries, as well as many other types of surgeries where the surgical site is difficult to view directly.
An example of an image guided surgery (IGS) system is shown in
As the disclosure of the '664 patent reveals, the typical image guided surgery system is complex and requires a great deal of equipment to provide real-time simulation and graphic display of the surgical site. What is needed is a system that allows for accurate bone resection or placement of surgical components without the expense and complexity of prior IGS systems.
In order to address this need, the present invention focuses on accurate placement of pins or screws into an object bone. The pins can then be used to position a standard cutting guide with the confidence that the bone resection conducted using the guide will be optimum. In order to accomplish this accurate pin placement, the present invention utilizes image guides surgical techniques, and particularly the use of a localizing sensor and position tracking elements associated with a surgical tool. In one embodiment of the invention, the surgical tool is a powered tool for placing a locating or support pin into a bone. The tool is outfitted with a position tracking element that can be sensed by the localizing sensor to determine the position of the tool in three-dimensional space. Similarly, the bone itself is provided with a position tracking element, at least initially, that will establish the spatial position of the bone.
A processor is linked to the localizing device or sensor to receive the data generated by the sensor. Software within the processor allows use selection of the proper location and attitude of the pin placement relative to the position tracking element associated with the bone. This position can be established using a pointer or other alignment device that is also provided with a position tracking device. The processor software can then calculate a relative difference between the spatial position of the bone and the spatial position of the proper pin location. Alternatively, if the bone is rigidly held so that it cannot move during the procedure, then only the spatial position of the pointer need be established.
Once the proper spatial location for the pin placement is determined, the surgeon manipulates the tool and its position data is sensed by the localizing device. The localizing device feeds this position information in real-time to the processor which compares the tool position to the proper location for the pin placement. In one embodiment of the invention, an annunciator provides a sensible signal to the surgeon to at least identify when the alignment of the tool matches the proper pin placement spatial position. The annunciator can provide an audible signal indicative of the relative spatial position. For instance, the audible signal can be generated only when the tool and pin placement spatial data coincide. Alternatively, the software can calculate a “closeness” value indicative of how close the tool is to its proper position, and then the audible annunciator can modulate the audible signal in relation to that “closeness” value.
In another embodiment, the annunciator is a visual indicator. The visual indicator can range from a light that illuminates when the spatial positions coincide to a series of lights that signal “closeness” and coincidence. The visual indicator can also constitute an image on a display associated with the processor that signifies the position of the tool relative to the proper pin placement position.
In a further embodiment of the invention, the tool itself is linked to the processor. The tool can be controlled automatically by the processor in relation to the spatial information evaluated by the processor software. In a specific embodiment, the tool is automatically activated when its spatial position coincides with the proper pin placement position. Where the tool is a pin driving tool, the tool is activated to drive the pin into the bone. Where the tool is a drill for driving a screw into the bone, the drill can be activated when it is properly positioned. As a further alternative, the drill can be constantly running but is configured to prevent the drill bit from engaging the bone unless and until the tool is properly positioned. In a specific embodiment, the drill is outfitted with a sheath that covers the rotating drill bit as the tool traverses the surface of the bone. Once the drill reaches its correct location, the sheath retracts, allowing the drill to be advanced into the bone.
In another aspect of the invention, a guide apparatus is provided that facilitates accurate placement of a guide or support pin into a bone. In one embodiment, the guide apparatus comprises a mounting body that is fastened to the bone in the proximity of a pre-determined guide pin location. A guide arm supports a position adjustment assembly over the guide pin location. The position adjustment assembly permits gross and fine adjustments of a pin guide. In this preferred embodiment of the invention, the pin guide is provided with a position tracking element that works through a localizing device or sensor to interactively evaluate the spatial position of the pin guide relative to the pre-determined guide pin location. Once the pin guide has been manipulated into coincidence with the pre-determined position, the surgeon can use the guide to drive a support pin into the bone.
Once the first pin has been properly position within the bone, a second pin can be introduced using the same guide apparatus. Alternatively, a cutting block can be mounted over the single support pin and then rotated into its proper alignment. The cutting block in this alternative embodiment is provided with its own position tracking element so that its spatial orientation can be evaluated in real-time. When the cutting block has been rotated into position, the cutting block itself is used as a pin guide for driving the second support pin into the bone.
It is one object of the present invention to provide systems and methods to facilitate making accurate cuts or resections of bone at a surgical site. It is a further object of the invention to utilize known image guide surgical techniques, while avoiding the high cost and complexity of such systems.
One benefit of the present invention is that it allows an orthopaedic surgeon to use conventional cutting blocks to perform bone resection procedures. Another benefit of the invention is that it can be used for a variety of functions in the orthopaedic arena, ranging from placing support pins for resection cutting blocks to accurate positioning of bone screws or pins. Other objects and benefits of the invention will become apparent upon consideration of the following written description taken together with the accompanying figures
FIGS. 9(a)-(c) are representations of sequential steps for positioning a cutting block using the present invention.
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the invention is thereby intended. It is further understood that the present invention includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles of the invention as would normally occur to one skilled in the art to which this invention pertains.
The present invention provides systems and methods that utilize image guided surgical techniques and systems. More particularly, the invention utilizes a localizing device, such as the localizing sensor 31 shown in
One embodiment of the present invention is depicted in
Once the pre-determined pin location has been established, the surgeon can manipulate a driving tool 40 in the vicinity of the pin location X. In one feature of the invention, the driving tool includes a position tracking element 47 that transmits to the localizing device 31, as shown in
Returning to the flowchart in
Once these coordinates coincide, the processor activates an annunciator 50 (
Once the annunciator signals spatial coincidence between the working end 41 and the location X, the tool 40 can be activated to place the fastener or pin into the femur F. Where the annunciator is sensed by the surgeon, the surgeon can operate the tool in a known manner. In an alternative, described in more detail herein, the processor 49 can direct the activation of the driving tool.
In certain embodiments of the invention, the annunciator provides a visual indication of spatial coincidence. In a specific embodiment, that visual indication can be projected on a display device, such as the monitor 35 of
In another embodiment of the invention, a pin driving tool 55 is configured to propel a pin 56 into bone. The tool can be a driving tool known for use in the orthopaedic field. The tool can be spring-loaded, electromagnetic, pneumatic or a combustion-type tool. The tool 55 includes a position tracking element 58, as described above to provide real-time data regarding the position and orientation of the tool relative to a pin implantation site on a bone. The tool 55 includes an on-board controller 67 that is connected via a communication link 62 to a master controller 60. The master controller 60 can be part of the processor 49 and operates to send signals to the on-board controller 67. The communication link 62 can be a wire connecting the two components or can be wireless, such as an RF transmission.
In one aspect of this embodiment, the annunciator 64 is associated with or mounted on the tool 55 in a position where it is readily visible to the surgeon. The tool 55 can include a plurality of LEDs 65a, 65b that are used to indicate closeness to and coincidence with the pin location. The annunciator is connected to the on-board controller 67 that responds to signals from the master controller 60 to activate the appropriate LED 65a, 65b. In a specific embodiment, one LED 65a can be activated as the surgeon searches for the proper pin location, while the other LED 65b can be activated once the pin 56 is situated over the pre-determined pin location.
In another embodiment of the present invention, the system contemplates automatically controlling the operation of the driving tool when its position coincides with the pre-determined pin position. The on-board controller 67 can also be connected to the motor 68 to activate the motor in response to a signal from the master controller 62. With this embodiment, the surgeon need not activate the tool in response to an annunciator signal. Automatic control thus facilitates the pin placement process.
This automatic control feature can also be implemented where the tool is a drill operable to prepare a bore in bone to receive a bone screw, for instance. Thus, as shown in
In a further alternative, it is contemplated that the drill 70 will be continuously running as the surgeon searches for the proper location to drill into the bone. In this instance, the present invention provides a mechanism for preventing access to the bone until spatial coincidence is achieved. In one specific embodiment, a sheath 80 is provided that encloses or covers the drill bit 71 as it is rotating. The sheath is connected to a retraction mechanism 82 that retracts or extends the sheath in response to a signal from the on-board controller 78. The retraction mechanism 82 can take on a variety of forms, such as the rack and pinion configuration depicted in
The drill 70 includes its own power switch 73 to provide the surgeon with absolute control over the activation of the drill. Thus, rather than rotating the drill bit 71 continuously during the procedure, the surgeon can elect to de-activate the drill until the bit is nearly aligned with the proper location. When the switch 73 is turned on, the on-board controller then takes charge of activating the motor 72 and/or retracting the sheath 80.
In an alternative approach, the bit 71 itself can be retracted into the body of the tool 70. With this approach, the retraction mechanism 82 can be engaged to the drill motor 72 and operate to move the motor back into the body of the tool with the bit 71 engaged thereto. In yet another alternative, the cutting edges of the drill bit 71 can be configured to be withdrawn as the bit is rotating, and then extended when a drilling operation is to be performed.
With the approaches of
These same aspects of the present invention can be used to drill into a bone at a predetermined position. For instance, as shown in
In a further approach of the present invention, a pin guide, rather than the pin itself, is navigated into position using the image guides surgical techniques described above. In this embodiment, a guide apparatus 10 includes a body 101 mounted to a bone F by mounting pins 103, as shown in
The guide arm 105 supports a position adjustment assembly 110 that is configured to align a pin guide 107 with the pre-determined location X. The pin guide 107 is outfitted with a tracking element 108, which can be similar to the tracking elements discussed above. The tracking element is used in conjunction with a localizing device, such as the device 31 described above, for a real-time determination of the spatial location of the pin guide 107 relative to the pin location X, the spatial coordinates of which have been determined beforehand. The relative position between these two points is calculated in the manner described above to determine whether the pin guide spatially coincides with the pin location. In the prior embodiments, the working tool was manually manipulated by the surgeon as the position of the tool was sensed in real-time. With the embodiment of
With this embodiment, the ultimate goal is to accurately position a standard cutting guide, such as the guide C shown in
In an alternative approach, the first pin P1 is positioned using the guide apparatus 100. The guide apparatus is then removed from the bone F. The cutting block C can be provided with a position tracking element 112 that sends signals to a localizing device in the manner described above. The position of the cutting block C can then be compared to a predetermined position value associated with either the cutting block or with the second support pin P2. In the latter case, the cutting block C is acting as like the pin guide 107 in that it is being positioned to align with a second pin location Y (
When the first pin P1 is placed within the bone, the cutting block C is mounted on that pin, as shown in
It can be appreciated that this embodiment of the invention accommodates a simple standard cutting block. Since the location of the mounting pins P1 and P2 is accurately navigated, there is not need for the cutting block to include any gross or fine adjustment capabilities. Of course, differently sized cutting blocks may be required for differently sized bones. This size difference can be accounted for in establishing the pre-determined pin placement locations X and Y.
The details of one specific embodiment of the position adjustment assembly 110 are shown in
In one embodiment of the invention, the position adjustment assembly 110 includes a gross positioning block 115 that is slidably mounted on the guide arm 105, as shown in
The gross positioning block 115 supports a fine adjustment block 117 with a fine adjustment mechanism 118 disposed therebetween. The fine adjustment block 117 supports a support arm 126 at an angle relative to the guide arm 105. Preferably, the support arm 126 is situated at a right angle to the guide arm, as depicted in
The fine adjustment mechanism 118 is configured to permit small changes in the position of the fine positioning block 117 relative to the gross positioning block 115. In other words, the fine adjustment mechanism 118 permits small adjustments in the spatial position of the pin guide 107 in the translational degree of freedom D1 (see also
As explained above, a support arm 126 projects from the fine positioning block 117. A second gross positioning block 115′ is slidably mounted on the support arm 126 in the same manner as the block mounted on the guide arm 105. A second fine positioning block 117′ and a second fine adjustment mechanism 118′ can be provided to permit fine adjustments in the translational degree of freedom D3. The gross and fine positioning adjustment capabilities in the degrees of freedom D3 and D4 relative to the support arm 126 can be the same as the adjustments accomplished relative to the guide arm 105 described above.
The fine adjustment block 117′ supports a vertical support arm 128 to which the pin guide 107 is mounted. The vertical support arm can be slidably mounted within the block 117′ for translation in the degree of freedom D5 and rotation in the degree of freedom D6. Again, the mount between the block 117′ and the vertical support arm 128 can include a friction bushing to control the movement of the arm relative to the block. Alternatively, the vertical support arm 128 can include splines 129 at its free end. The fine positioning block 117′ can include a thumbwheel gear 131 that meshes with the splines 129 to permit fine rotational adjustments of the arm 128 in the degree of freedom D6. The splines 129 allow the arm 128 to translate vertically relative to the thumbwheel gear 131 without disturbing the fine rotational adjustment capability. Fine adjustment in the vertical translational degree of freedom D5 is typically not required because the pin guide 107 can be moved into direct contact with the bone F once the positional adjustments have been made in the other degrees of freedom. The fine rotational adjustment capability provided by the splines 129 and thumbwheel gear 131 can be implemented in the gross positioning blocks 115 and 115′ to accommodate fine rotational adjustments in the degrees of freedom D2 and D4.
In using the guide apparatus 100 of the present embodiment, the gross position of the pin guide 107 can be established relative to bony landmarks on the bone F. The fine adjustment thumbwheel gears 120, 120′ and 131 can be manipulated as the real-time spatial position of the pin guide 107 is reported using the position tracking element 108. When the spatial position of the pin guide coincides with the pre-determined pin location(s) X (or Y), the pin guide can be moved into contact with the bone and the surgeon can drive a pin P1 (or P2) into the bone using a standard driving tool.
The systems and methods of the present invention are not limited to the pin placement or drilling operation s described above, or to any particular location in the body. For instance, the bone being prepared can be anywhere in the skeletal structure, such as the shoulder, elbow, hip, ankle, spine and cranium. The approach described in connection with FIGS. 9(a)-(c) can be used for guide placement of a bone plate, instead of the cutting guide shown the figures. For instance, in some orthopaedic procedures, a bone plate is fastened to a bone spanning a fracture. Accurate placement of the plate and associated bone fasteners can be facilitated with the present invention.
The invention is particularly suited for precision bone working operations. Thus, the invention is not limited to pin placement or drilling into bone, but can include other operations, such as cutting, burring, polishing, grinding, rasping, or other similar operations. For instance, in one alternative procedure, it is necessary to prepare the distal end of the femur to receive an femoral implant. This preparation can require shaving, burring and polishing the distal end of the femur using an appropriate tool. The tool would carry the position locating device 47 described above so that the working end of the tool can be established in real-time. The tool can be activated as described above when it aligns with an array of stored locations or falls within a range of pre-determined locations on the bone. Thus, in the case of a burring tool, the surgeon can move the tool across the distal end of the femur while the tool spatial position is determined by the processor 49. When the burring tool is at a location that has been previously determined to require finishing, the surgeon can be prompted to activate the tool by an annunciator 50, or the tool can be automatically activated in the manners described above. Other tools can be similarly manipulated using the techniques and systems of the present invention.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same should be considered as illustrative and not restrictive in character. It is understood that only the preferred embodiments have been presented and that all changes, modifications and further applications that come within the spirit of the invention are desired to be protected.
