This invention pertains generally to a method and apparatus for performing pedicle screw fusion surgery.
Pedicle screw fusion surgery generally involves the insertion of pedicle screws into a short tubular structure connecting the vertebral body with the lamina and represents the strongest portion of the vertebra found on each side of the vertebra. This allows the pedicle screws to grab into the bone of the vertebral body, giving them a solid hold on the vertebra. Once the pedicle screws are placed, they are attached to metal rods that connect the screws together. This creates a stiff metal frame that holds the vertebrae still and thereby facilitates decompression for pain relief and healing. Bone graft is typically placed around the back of the vertebra to help the vertebrae heal together, or fuse.
Pedicle screw fusion procedures can incorporate surgical navigation technology wherein the location of a medical device is measured and virtually superimposed on a patient image. The patient image may be pre-recorded, near real-time, or real-time, and is preferably obtained using known imaging technology such as X-ray, computed tomography (CT), magnetic resonance imaging (MRI), or ultrasound (US). Conventional navigation technology measures the location of a remote unit attached to the medical device relative to a reference unit. Patient motion can be taken into account by rigidly mounting the reference unit directly onto the patient. A reference unit attached in this manner is also referred to as a dynamic reference because it moves along with the patient.
A number of medical instruments including an awl, a blunt probe, a ball tip probe-feeler, and a tap are commonly implemented during pedicle screw fusion surgery. Awls have a sharp pointed end that is used to create a shallow pilot hole opening through the bone surface. The pointed end of the awl is particularly well adapted to pedicle screw fusion surgery as blunt instruments would be prone to sliding off the pedicle's dome shaped surface. The blunt probe is used to carve the hole from the pedicle cortex into the vertebal body at an appropriate angle and depth. The ball tip probe-feeler is implemented to verify pedicle integrity via a process of palpation and thereby ensure no violation of the pedicels walls occurred prior to implantation. If a non-significant violation is detected, the pedicle screw is either redirected or the site is abandoned. A tap includes a cutting edge adapted to form internal threads in the cancellous bone of the pedicle canal. The internal treads formed by the tap engage complementary external pedicle screw threads to retain and secure the pedicle screws. These taps that are specifically matched to implant screw counterparts, are commonly used after the pedicle hole is created and prior to implant screw placement.
Conventional awls, blunt probes and taps are individual medical instruments adapted to perform a specialized function as previously described. These individual instruments must be switched back and forth many times during the course of a single pedicle screw fusion procedure. Though these instruments are necessary for the conventional technique, the intra-operative steps associated with switching the instruments are a potential source of inefficiency and can prolong the overall duration of a procedure.
The above-mentioned shortcomings, disadvantages and problems are addressed herein which will be understood by reading and understanding the following specification.
In an embodiment, a medical device adapted to facilitate pedicle screw fusion surgery includes a proximal end and a sharp distal end opposite the proximal end. The distal end is configured to allow the medical device to function as an awl. The medical device also includes a body portion defined between the proximal end and the distal end, and a threaded section defined by the body portion near the distal end. The threaded section is configured to allow the medical device to function as a tap. Accordingly, the medical device provides a single tool adapted to function as both an awl and a tap.
In another embodiment, a system adapted to facilitate pedicle screw fusion surgery includes a position detection process in communication with a remote unit and a reference unit. The position detection process is configured to estimate the location of the remote unit relative to the reference unit. The system also includes a medical device attached to the remote unit. The medical device includes a proximal end, a distal end, and a body portion defined therebetween. The medical device also includes a generally pointed tip defined at the distal end. The pointed tip is configured to allow the medical device to function as an awl. The medical device also includes a threaded section defined by the body portion near the distal end. The threaded section is configured to allow the medical device to function as a tap. The system also includes a display operatively connected to the position detection device. The display is adapted to convey the location of the medical device relative to the reference unit.
In yet another embodiment, a method for securing a pedicle screw to a vertebra includes creating a pilot hole in a pedicle with a medical device, forming a screw hole in the vertebra at the location of the pilot hole with the medical device, forming an internal thread disposed about the periphery of the screw hole with the medical device, and inserting an externally threaded pedicle screw into the internally threaded screw hole. Wherein creating a pilot hole, forming a screw hole, and forming an internal thread are all performed with a single medical device.
Various other features, objects, and advantages of the invention will be made apparent to those skilled in the art from the accompanying drawings and detailed description thereof.
a is a detailed perspective illustration of the distal end of the medical device of
b is a detailed perspective illustration of the distal end of the medical device of
a is a cross sectional view of a vertebra having a pilot hole formed in each pedicle;
b is a cross sectional view of a vertebra having a screw hole formed in each pedicle;
c is a cross sectional view of a vertebra having an internally threaded hole formed in each pedicle;
d is a cross sectional view of a vertebra having a pedicle screw inserted into each pedicle; and
In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments that may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments, and it is to be understood that other embodiments may be utilized and that logical, mechanical, electrical and other changes may be made without departing from the scope of the embodiments. The following detailed description is, therefore, not to be taken as limiting the scope of the invention.
Referring to
The reference unit 14 is preferably rigidly attached to a patient 28 near the target operation site 30 (e.g., a portion of the spine) in a conventional manner. A reference unit attached in this manner is also referred to as a “dynamic reference” because it moves along with the patient. The remote unit 16 is attached to the medical device 10. The present invention will hereinafter be described in accordance with an embodiment wherein the reference unit 14 includes a field generator 38, and the remote unit 16 includes one or more field sensors 40. It should, however, be appreciated that according to alternate embodiments the reference unit may include the field sensors and the remote unit may include the field generator.
The field generator 38 in the reference unit 14 generates a position characteristic field 44 in an area that includes the target operation site 30. The field sensors 40 in the remote unit 16 produce sensor signals (not shown) in response to the sensed position characteristic field 44. The sensor signals are transmitted or input into the position detection process 20. The sensor signals may be transmitted via communication line 46, or may be wirelessly transmitted. The position detection process 20 is adapted to estimate the location of the remote unit 16 relative to the reference unit 14. A known calibration procedure can be implemented to estimate the location of the distal end or tip 36 of the medical device 10.
The location of the medical device 10 may be conveyed via the display 18. According to one embodiment, a graphical representation 48 of the distal end 36 is virtually superimposed onto a patient image 50. More precisely, the graphical representation 48 of the distal end 36 is virtually superimposed onto the portion of the image 50 that corresponds to the actual location of the distal end 36 within the patient 28. The graphical representation 48 may include a dot or cross hairs identifying just the distal end 36, or may include a more complete rendering showing the medical device 10 in detail.
According to one embodiment, the patient image 50 is obtained prior to the medical procedure using known imaging technology such as X-ray, computed tomography (CT), magnetic resonance imaging (MRI), or ultrasound (US). Additionally, during the course of the medical procedure, the imaging device 22 may be implemented to observe the patient 28 in real-time or near real-time. Therefore, the pre-recorded patient image 50 can be replaced with a real-time patient image or a near real-time image as desired. According to an exemplary embodiment, the imaging device 22 may include a fluoroscopic X-ray device mounted to a C-arm, however, other imaging devices may also be implemented.
Referring to
The body portion 52 of the medical device 10 defines a threaded section 58 near the distal end 36. The threaded section 58 is similar to that of a conventional tap (not shown), and includes one or more external threads 60 defining a cutting edge 62. The cutting edge 62 is configured to cut both cortical bone and cancellous bone, and thereby form an internally threaded hole 78 (shown in
Referring to
Referring to
a-3d, illustrate a sequence of procedures that may be performed by the medical device 10 during pedicle screw fusion surgery. Referring to
Referring to
Referring to
At step 102, the target operation site 30 (shown in
At step 104, an optimal configuration for the threaded section 58 of the medical device 10 (shown in
At step 106, the medical device point 56 is implemented to pierce the pedicle 76 (shown in
At step 108, the screw holes 77 (shown in
At step 110, the threaded section 58 of the medical device 10 (shown in
At step 114, a pedicle screw 80 (shown in
Steps 102-114 are repeatable at other sights to place additional pedicle screws 80. Advantageously, step 102-110 can all be performed with a single device (i.e., the medical device 10). Performing these steps in a more conventional manner would require at least three separate tools (i.e., an awl; a probe; and a tap), and the surgeon would have to switch back and forth between these separate tools throughout the procedure. It can therefore be seen that the method 100 which implements a single medical device 10 to perform a variety of different procedures saves the time otherwise required for switching and positioning new instruments during the course of the procedure.
While the invention has been described with reference to preferred embodiments, those skilled in the art will appreciate that certain substitutions, alterations and omissions may be made to the embodiments without departing from the spirit of the invention. Accordingly, the foregoing description is meant to be exemplary only, and should not limit the scope of the invention as set forth in the following claims.