Tracker device

Abstract

The purpose of the present invention is to provide a tracker device which is less invasive to a patient, is excellent in safety, can be firmly fixed to the pelvis of the patient, can be easily removed after surgery, and is less invasive to the skin and bone after removal. This tracker device constitutes a navigation system used when performing orthopedic surgery, and comprises: a tracker unit (110) having optical markers (111)-(114); and a fixing member (120) for fixing the tracker unit (110) to the pelvis of a patient. The fixing member (120) comprises a spiral coil having a pointed end (121).

Description

Tracker Device

[0001] The present invention relates to tracker devices, and in particular bone tracker devices, that are part of navigation and robotic systems used in performing orthopedic surgical procedures.

[0002] Conventionally, for example, in total hip replacement surgery, navigation systems and robotic systems have been proposed that assist in guiding and inserting an acetabular cup into the patient's acetabulum in an ideal position and direction (see Patent Document 1 below).

[0003] The navigation system includes a stereo camera with a near-infrared light emitting unit, a pelvis tracker unit fixed to the patient's pelvis, a registration tracker unit positioned at a landmark or reference position on the pelvis, a tracker unit coupled to an acetabular cutting tool, and a femur tracker unit coupled to the patient's femur.

[0004] Each of these tracker units is equipped with multiple or single reflective markers or self-luminous markers, and by photographing these tracker units with a stereo camera and measuring the positions of the individual trackers using the principles of trigonometry, the relative positional relationships between the tracker units can be obtained.

[0005] After the positional relationship thus determined is registered in the computing device, the positional relationship between the pelvis tracker unit and the tracker unit connected to the acetabular cutting tool is continuously measured (tracked), thereby making it possible to grasp changes in the relative position of the acetabular insertion tool with respect to the patient's pelvis (changes associated with body movement and / or tool movement). As a result, in total hip replacement surgery, an implant called an acetabular cup can be placed in the correct pelvic position with the desired lateral and anteversion angles.

[0006] JP 2014-508549 A

[0007] Pelvis tracker units with markers are typically fixed to the patient's pelvis using bone screws. Specifically, a pilot hole is first drilled through an incision in the skin into the iliac crest of the pelvis using an electric drill, and then a self-tapping bone screw is inserted.

[0008] However, in structures where the marker section and bone tracker unit are separate, the fixation member consisting of a bone screw that attaches the tracker section does not necessarily provide sufficient resistance to pull-out when implanted into the pelvis (cancellous portion). This can lead to problems such as the tracker section becoming unsteady due to dislodging from the pelvis or loosening of the screw, resulting in poor positioning accuracy. This loosening is particularly likely to occur when changing patient position during surgery, which is a major issue for applications requiring high implant placement accuracy and precision. Furthermore, because pins or bone screws, typically with an outer diameter of 4–6 mm or more, are inserted through incisions larger than several millimeters, postoperative scars (suture marks) remain on the skin in addition to the incisions made for implant placement. Furthermore, holes remain in the pelvis after the bone screws are removed, which take time to close.

[0009] Furthermore, the invasiveness of this fixation method to the patient can be extremely dangerous. Cases have been reported in which the electric drill deviated from its intended direction when drilling pilot holes, causing damage to the pelvis or blood vessels (H. Kan, I. Nusem / Arthroplasty Today 19(2023)101070). Therefore, solutions such as increasing the number of bone screws or increasing their diameter have limitations from the perspective of patient safety.

[0010] The present invention has been made in light of the above circumstances, and an object of the present invention is to provide a tracker device that is minimally invasive to the patient, highly safe, can be firmly fixed to the patient's pelvis, can be easily removed after surgery, leaves only small scars on the skin after removal, and is minimally invasive to the bones.

[0011] The tracker device of the present invention is a tracker device that constitutes a navigation system used in performing orthopedic surgery, and is characterized in that it comprises a tracker unit having at least one optical marker and a fixation member for fixing the tracker unit to a patient's bone, the fixation member being a helical coil having a pointed end.

[0012] In the tracker device of the present invention, it is preferable that the spiral coil is formed from a wire having a circular cross section, the wire diameter (d) being 1.2 to 3.0 mm, the coil diameter (D) being 2.8 to 12 mm, the coil pitch (p) being 2.4 to 30 mm, and the coil length (L) being 8 to 140 mm. In this case, it is particularly preferable that the ratio of the coil diameter to the wire diameter (D / d) be 1.5 to 5, and the coil pitch to the wire diameter (p / d) be 1.35 to 6.

[0013] In the tracker device of the present invention, the spiral coil is preferably formed from a wire having a polygonal cross section, such as a circle, semicircle, ellipse, triangle, quadrangle (square, rhombus, rectangle, trapezoid, etc.), pentagon, or hexagon. These wires tend to twist around their central axis when formed into a spiral coil. This twisting can widen the entrance or penetration path when screwing the coil body into the bone, loosening the fixation of the spiral coil to the pelvis or other bone. Therefore, a circular or polygonal shape is desirable.

[0014] In the tracker device of the present invention, if the tip of the spiral coil is machined with a cutting edge, it is preferable because there is no need to drill a pilot hole when penetrating the cortical bone on the bone surface.

[0015] It is also preferable that the fixing member is detachable from the tracker unit. It is also preferable that the tracker unit has at least one light-reflecting marker or light-emitting marker. The tracker unit may have a two-dimensional tracker on which optically readable information (image information such as a two-dimensional matrix) is printed.

[0016] The tracker device of the present invention is suitable for use in fixing to a patient's bones during total joint replacement surgery. For example, it is suitable for use in fixing to a patient's pelvis or femur during total hip replacement surgery. It is also suitable for use in fixing to a patient's femur or tibia during total knee replacement surgery. It is also suitable for use in fixing to a patient's necessary bones during other total joint replacement surgery (e.g., shoulder joint, etc.). However, the tracker device is not limited to use in total joint replacement surgery, and can also be used in other surgeries requiring precise navigation (e.g., pelvic fracture repair surgery, etc.).

[0017] According to the tracker device of the present invention, the fixing member is composed of a helical coil having a pointed end (preferably with a sharp cutting edge), which allows for easy attachment and detachment to the patient's bone (pelvis). Furthermore, the attachment operation of the tracker device can be performed manually without using an electric drill or the like, and the depth can be adjusted slowly, making it highly safe. Once attached, the tracker device of the present invention is firmly fixed to the bone, providing extremely high resistance to removal or loosening. Removal can also be performed manually.

[0018] Furthermore, any scars left on the skin after removing the tracker device of the present invention are caused by the penetration of the wire of the spiral coil (holes equivalent to the diameter of the wire), and are significantly smaller than those left when pins or bone screws are used, so in most cases, suturing is not required. Furthermore, because only a small amount of bone tissue is removed when the spiral coil is implanted into the bone, the hole left in the bone after the fixation member (spiral coil) is removed is also small. Therefore, use of the tracker device of the present invention is extremely minimally invasive to the patient.

[0019] FIG. 1 is a front view showing a tracker device of a first embodiment of the present invention; FIG. 2 is a side view showing the tracker device of the first embodiment; FIG. 3 is a cross-sectional view of a fixing member constituting the tracker device of the first embodiment; FIG. 4 is a front view showing a tracker device of a second embodiment of the present invention; FIG. 5 is a cross-sectional view of a fixing member constituting the tracker device of the second embodiment; FIG. 6 is a front view showing a tracker device of a third embodiment of the present invention; FIG. 7 is a front view showing a tracker device of a fourth embodiment of the present invention.

[0020] First Embodiment A tracker device 100 of this embodiment shown in FIGS. 1A to 1C is a tracker device that constitutes a navigation system used when performing total hip replacement surgery, and is fixed to the patient's pelvis.

[0021] The tracker device 100 includes a tracker unit 110 and a fixation member 120. During a hip replacement surgery, the tracker unit 110 is positioned outside the patient's body, and the fixation member 120 has its distal side implanted in the pelvis and its proximal side located outside the body.

[0022] The tracker unit 110 that constitutes the tracker device 100 has four reflective markers (tracking targets) 111 to 114 that are near-infrared reflective ball markers.

[0023] A fixing member 120 is detachably attached to the distal end of the tracker unit 110. The mechanism for attaching and detaching the fixing member 120 is not particularly limited, and an example of such an attachment mechanism is a locking mechanism such as a screw. The fixing member 120, which constitutes the tracker device 100, is made of a helical coil having a pointed end 121 at its distal end.

[0024] The fixing member 120 consisting of a spiral coil is formed from a wire (round wire) having a circular cross section, and the tip 121 of the fixing member 120 is approximately conical or approximately truncated conical (the apex of the truncated cone may be rounded).

[0025] The fixing member 120 may be made of a metal such as stainless steel, Ni-Ti alloy, Co-Cr alloy, or tantalum, or may be made of any of these metals coated with a low-friction resin.

[0026] The diameter d of the wire forming the fixation member 120 is usually preferably 1.2 to 3.0 mm, and more preferably 1.8 to 2.5 mm. If the wire diameter d is too small, it becomes difficult to form a fixation member with high pull-out strength. On the other hand, if the wire diameter d is too large, it becomes difficult to fully achieve the objectives of the present invention, which are minimal invasiveness and minimal scarring.

[0027] The outer diameter (coil diameter) D of the fixing member 120 is preferably 2.8 to 12 mm, and more preferably 5 to 10 mm.

[0028] Here, the ratio (D / d) of the coil diameter D to the wire diameter d is preferably 1.5 to 5. A fixation member with an excessively small ratio (D / d) cannot exhibit sufficient pull-out strength. On the other hand, a fixation member with an excessively large ratio (D / d) is difficult to embed in bone (attach the tracker device) and remove from bone (remove the tracker device).

[0029] The pitch (coil pitch) p of the fixing member 120 is preferably 2.4 to 30 mm.

[0030] The ratio (p / d) of the coil pitch p to the wire diameter d is preferably 1.35 to 6. A fixation member with an excessively small ratio (p / d) (densely wound) cannot fully achieve the goal of minimal invasiveness. On the other hand, a fixation member with an excessively large ratio (p / d) (loosely wound) cannot exhibit sufficient pull-out strength.

[0031] The length (coil length) L of the fixing member 120 is preferably 8 to 140 mm in order to ensure sufficient pull-out resistance.

[0032] Prior to performing hip replacement surgery, the tracker device 100 of this embodiment is attached to the patient's pelvis. Specifically, the tip 121 of the fixation member 120 is placed in contact with the patient's skin covering the pelvis (the attachment site of the device), and the fixation member 120 is rotated about its axis—in this example, clockwise—to introduce the tip 121 into the body and reach the pelvis. If necessary, the tip is then orientated perpendicular to the cortical bone and twisted to penetrate it. The fixation member 120 is then further rotated in a direction along its original spiral shape, spiraling it forward and implanting it into the pelvis. This allows the tracker device 100 to be attached to the patient's pelvis.

[0033] Here, the operation of embedding the fixing member 120 into the pelvis to attach the tracker device 100 may be performed with the tracker unit 110 attached to the fixing member 120, but it is also possible to first remove the fixing member 120 from the tracker unit 110, and then embed the removed fixing member 120 into the pelvis using a jig such as a T-shaped handle, and then attach the tracker unit 110 to the proximal end of the fixing member 120 extending from the skin.

[0034] The reflective markers 111-114 provided on the tracker unit 110 can be photographed (recognized) by an infrared camera that constitutes the navigation system. The "position of the tracker unit 110 on the patient's pelvis" can be determined by placing registered trackers equipped with reflective markers similar to the reflective markers 111-114 at multiple landmarks or reference positions on the pelvis (e.g., the anterior superior iliac spine, the anterior inferior iliac spine, and the iliac crest), photographing these with an infrared camera, and measuring the relative positional relationship between each registered tracker and the tracker unit 110. The "position of the tracker unit 110 on the patient's pelvis" determined in this manner is registered in the navigation system's computer. This allows changes in the position and orientation of the patient's pelvis to be ascertained by tracking the position (changes) of the tracker unit 110.

[0035] After the hip replacement surgery is completed, the tracker device 100 is removed from the pelvis. Specifically, the fixation member 120 is rotated leftward (counterclockwise) around its axis in this example, and the fixation member 120 is then retracted along the implanted path and removed from the pelvis, thereby removing the tracker device 100.

[0036] The tracker device 100 of this embodiment allows for easy attachment and detachment to the patient's pelvis. Furthermore, the attachment and detachment of the tracker device 100 can be performed manually using a jig (e.g., a T-shaped handle for rotating the fixation member 120) as needed, resulting in excellent safety. Furthermore, the wire forming the fixation member 120 embedded in the pelvis is embedded within the bone tissue. Unlike conventional screws, which are anchored to the bone by the unevenness of the peaks and valleys on their surface, the wire contacts the bone along the spiral perforations. Therefore, the tracker device 100 of the present invention is firmly fixed to the pelvis and offers extremely high pullout resistance when pulled out along the screw's central axis or the central axis of the spiral circle. Furthermore, after removal of the fixation member 120, the scar remaining on the skin is extremely small, equivalent to the diameter of the wire, and no treatment such as suturing is required. Furthermore, the hole remaining in the pelvis is small and can be closed by bone tissue, which regenerates in a short period of time. Taking these factors into consideration, the tracker device 100 of this embodiment is extremely minimally invasive to the patient.

[0037] Second Embodiment A tracker device 200 of this embodiment shown in FIGS. 2A and 2B is a tracker device that constitutes a navigation system used when performing total hip replacement surgery, and is fixed to the patient's pelvis in the same manner as the tracker device 100 of the first embodiment.

[0038] This tracker device 200 includes a tracker unit 210 and a fixing member 220. The configuration of the tracker unit 210 (reflective markers 211 to 214) is similar to that of the tracker unit 110 (reflective markers 111 to 114) in the first embodiment.

[0039] The fixing member 220 constituting the tracker device 200 is made of a helical coil having a pointed end 221. The fixing member 220 is formed from a wire having a square cross section, and the pointed end 221 of the fixing member 220 is in the shape of a substantially square pyramid or a substantially square truncated pyramid (which may have a rounded apex). The fixing member 220 may be made of the same material as the fixing member 120 of the tracker device 100 of the first embodiment.

[0040] The thickness of the wire material forming fixing member 220 (length s of the sides of the square cross section) is preferably 1.5 to 3.0 mm, and more preferably 1.8 to 2.5 mm. The outer diameter (coil diameter) D, pitch (coil pitch) p, and length (coil length) L of fixing member 220 are the same as those of fixing member 120 of tracker device 100 of the first embodiment.

[0041] The tracker device 200 of this embodiment can achieve the same effects as those achieved by the tracker device 100 of the first embodiment.

[0042] <Third Embodiment> A tracker device 300 of this embodiment shown in FIG. 3 is a tracker device that constitutes a navigation system used when performing total hip replacement surgery, and is fixed to the patient's pelvis in the same manner as the tracker device 100 of the first embodiment.

[0043] This tracker device 300 includes a tracker unit 310 and a fixing member 320. The configuration of the tracker unit 310 (reflective markers 311 to 314) is similar to that of the tracker unit 110 (reflective markers 111 to 114) in the first embodiment.

[0044] Fixing member 320 constituting tracker device 300 is made of a helical coil having a tip 321 at its distal end. Fixing member 320 made of a helical coil is formed from a wire having a circular cross section (round wire), and tip 321 is machined to have a cutting edge. That is, fixing member 320 has the same configuration as fixing member 120 of tracker device 100 of the first embodiment, except that tip 321 is machined to have a cutting edge.

[0045] As shown in FIG. 3, the cutting edge processed tip 321 has a substantially regular triangular pyramid shape, and edges are formed on the sides (side edges) of the regular triangular pyramid.

[0046] The tracker device 300 of this embodiment can achieve the same effects as the tracker device 100 of the first embodiment. Furthermore, the cutting edge processing applied to the tip 321 of the fixing member 320 increases its sharpness, and the formed edge can efficiently scrape away cortical bone tissue on the surface of the pelvis, making it possible to more smoothly embed the fixing member 320 in the pelvis.

[0047] Fourth Embodiment A tracker device 400 of this embodiment shown in FIG. 4 is a tracker device that constitutes a navigation system used when performing total hip replacement surgery, and is fixed to the patient's pelvis.

[0048] This tracker device 400 includes a tracker unit 410 and a fixing member 420. The configuration of the fixing member 420 is similar to that of the fixing member 120 in the first embodiment.

[0049] The tracker unit 410 that constitutes the tracker device 400 has a two-dimensional tracker on which optically readable information (image information such as a two-dimensional matrix) is printed.

[0050] The tracker device 400 of this embodiment can achieve the same effects as those achieved by the tracker device 100 of the first embodiment.

[0051] Although the embodiments of the present invention have been described above, the present invention is not limited to these and various modifications are possible. For example, the marker mounted on the tracker unit may be a self-luminous marker. Furthermore, the tracker unit may be equipped with an optical sensor. Furthermore, the cross section of the wire forming the fixing member (spiral coil) may be quadrilateral (e.g., diamond, rectangle, trapezoid) other than a square, semicircular, elliptical, triangular, pentagonal, or hexagonal. Furthermore, the tip of the fixing member may be subjected to cutting edge processing other than that shown in the third embodiment. Furthermore, the tracker device of the present invention can be fixed to the femur, tibia, or other bones of a patient in addition to the pelvis.

[0052] 100 Tracker device 110 Tracker unit 111 to 114 Reflective marker 120 Fixing member 121 Tip of fixing member 200, 300, 400 Tracker device 210, 310, 410 Tracker unit 220, 320, 420 Fixing member 221 321, 421 Tip of fixing member

Claims

1. A tracker device that constitutes a navigation system used in performing orthopedic surgery, the tracker device comprising: a tracker unit having at least one optical marker; and a fixation member for fixing the tracker unit to a patient's bone, the fixation member comprising a helical coil having a pointed end.

2. The tracker device of claim 1, wherein the helical coil is formed from wire having a circular cross-section, the wire having a diameter (d) of 1.2 to 3.0 mm, a coil diameter (D) of 2.8 to 12 mm, a coil pitch (p) of 2.4 to 30 mm, and a coil length (L) of 8 to 140 mm.

3. The tracker device of claim 2, wherein the ratio of the coil diameter to the wire diameter (D / d) is between 1.5 and 5, and the coil pitch to the wire diameter (p / d) is between 1.35 and 6.

4. The tracker device of claim 1, wherein the helical coil is formed from wire having a polygonal cross section, such as a circular, semicircular, elliptical, triangular, square, pentagonal, or hexagonal cross section.

5. A tracker device according to any one of claims 1 to 4, wherein the pointed end of the spiral coil is machined to have a cutting edge.

6. A tracker device according to any one of claims 1 to 4, wherein the fixing member is detachable from the tracker unit.

7. A tracker device according to any one of claims 1 to 4, wherein the tracker unit has at least one light-reflecting or light-emitting marker.

8. A tracker device according to any one of claims 1 to 4, wherein the tracker unit has a two-dimensional tracker on which optically readable information is printed.

9. A tracker device according to any one of claims 1 to 4, which is fixed to a patient's bone when performing a total joint replacement surgery.

10. The tracker device of claim 9, which is secured to a patient's pelvis during hip replacement surgery.

11. The tracker device of claim 9, which is secured to a patient's femur during hip replacement surgery.

12. The tracker device of claim 9, which is secured to a patient's femur or tibia during knee replacement surgery.

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