Electromagnetic probe for intramedullary nail and navigation system comprising same

Abstract

The invention relates to an electromagnetic probe for an intramedullary nail (100), the electromagnetic probe (1) comprising: a hollow tube body (10) extending along a longitudinal axis; the probe head (20) is located at the far end of the hollow tube body and provided with a smooth head end, and the size of the probe head is matched with the size of an inner hole (102) of an intramedullary nail; at least two sensors (30) arranged in the hollow tube body and / or the probe head (20), the at least two sensors being spaced apart by a predetermined distance in the longitudinal direction of the hollow tube body; and a carrier member (40, 40 ') adapted to carry at least two sensors and arranged adjacent to or at least partially in the probe head (20). The invention also relates to a surgical navigation system comprising such an electromagnetic probe.

Description

Technical Field

[0001] The invention relates to a positioning device used for orthopedic surgery, in particular to intramedullary nail placement surgery. Background Art

[0002] Intramedullary nail is an internal fixation device commonly used in orthopedic surgery, mainly used to treat long bone fractures. It is inserted into the bone marrow cavity to tightly connect the two ends of the fracture, provide stable support for the bones, and thus promote fracture healing.

[0003] In intramedullary nailing surgery, in order to fix the intramedullary nail to the bones at both ends of the fracture, the intramedullary nail needs to be accurately positioned so that the operator knows the position of the intramedullary nail in the patient's body and the precise position of the locking hole of the intramedullary nail, so as to use a drill to drill a hole at the location of the locking hole and screw in the locking nail for fixation.

[0004] Currently, a variety of technologies are known for positioning intramedullary nails, such as positioning technology based on X-ray imaging, optical tracking systems, electromagnetic navigation technology, and magnetic field transmitter positioning systems.

[0005] The application of electromagnetic navigation technology in intramedullary nail surgery has many advantages, such as significantly reducing radiation exposure; achieving high-precision positioning comparable to optical navigation, by establishing an electromagnetic field grid in the surgical area to track the position of the intramedullary nail in real time; being able to display the position of the intramedullary nail in the patient's body in real time and superimpose it with the preoperative three-dimensional image to help doctors operate more intuitively; compared with the optical navigation system, electromagnetic navigation does not require a clear line of sight, so it can still work normally when the surgical area is crowded or the line of sight is blocked; it can quickly locate, reducing surgical preparation time and patient waiting time; and it is highly flexible and can be quickly adjusted according to surgical needs. Therefore, the application of electromagnetic navigation technology in intramedullary nail surgery not only improves the accuracy and safety of the surgery, but also reduces the patient's radiation exposure and surgical time, and has a high clinical application value.

[0006] In intramedullary nail surgery, electromagnetic navigation technology usually requires the use of a probe to achieve precise positioning and navigation. The probe plays a key role in the electromagnetic navigation system. It detects magnetic field changes in the surgical area through built-in sensors and transmits this information to the navigation system in real time.

[0007] However, in intramedullary nail surgery, existing probe types have some disadvantages and limitations. For example, the positioning accuracy of the probe is highly dependent on the accuracy of preoperative registration; it cannot completely replace intraoperative fluoroscopy, and in some complex cases, intraoperative fluoroscopy may still be required to further confirm the position, which means that radiation cannot be completely avoided; the use of the probe may be limited by the space in the surgical area, etc.

[0008] Therefore, it is necessary to provide an improved intramedullary electromagnetic probe. Summary of the invention

[0009] An object of the present invention is to solve at least one aspect of the above-mentioned problems and defects in the prior art.

[0010] According to one aspect of the present invention, an electromagnetic probe for an intramedullary nail is provided, the electromagnetic probe comprising: a hollow tube body extending along a longitudinal axis; a probe head located at the distal end of the hollow tube body, the probe head having a rounded head end, and the size of the probe head matching the size of the inner hole of the intramedullary nail; at least two sensors arranged in the hollow tube body and / or the probe head, the at least two sensors being separated by a predetermined distance in the longitudinal direction of the hollow tube body; and a bearing member, the bearing member being suitable for carrying the at least two sensors and being arranged adjacent to the probe head or at least partially located in the probe head. The at least two sensors include a first electromagnetic sensor and a second electromagnetic sensor, the bearing member having a spacing portion and a groove portion arranged on both longitudinal sides of the spacing portion, the first electromagnetic sensor and the second electromagnetic sensor being respectively arranged in the grooves of the corresponding groove portions.

[0011] Optionally, a radial dimension of the probe head is larger than an outer diameter of the hollow tube body.

[0012] Optionally, the probe head has a dome-shaped or hemispherical tip.

[0013] Optionally, the load-bearing member is at least partially cylindrical and has a "T"-shaped longitudinal cross-section, the spacing portion protrudes radially relative to the groove portion to form a "T"-shaped middle protrusion, and the spacing portion has a size adapted to the hollow portion of the hollow tube body, the groove portions are arranged on both sides of the middle protrusion to form a "T"-shaped top side extension, and the groove is configured as an open groove located in the top side extension and radially recessed from the surface of the groove portion.

[0014] Optionally, the bearing member is columnar and has a size adapted to fit into the hollow portion of the hollow tube body, and the groove is configured as an inner hole in the groove portion.

[0015] Optionally, a longitudinally extending recess is provided on the outer peripheral portion of the bearing member, and a core wire connected to the sensor can be at least partially arranged in the recess.

[0016] Optionally, the intermediate protrusion formed by the spacer portion has a chamfer on a side facing the probe head. In another optional embodiment, the end of the bearing member has a chamfer.

[0017] Optionally, the electromagnetic probe further comprises a single coupling plug, and the at least two sensors are connected to the single coupling plug via respective core wires.

[0018] Optionally, the electromagnetic probe further comprises a memory disposed in the coupling plug and used to record position parameters associated with the probe head.

[0019] Optionally, the electromagnetic probe further comprises a wire-fixing structure located at the proximal end of the hollow tube body, for fixing the position of a core wire connected to at least two sensors.

[0020] Optionally, the wire clamping structure comprises at least two pins, each pin having a slot extending around the periphery thereof, and the core wire is adapted to be positioned in the slot at least partially around the pin.

[0021] Optionally, the electromagnetic probe also includes a plurality of annular grooves arranged on the outer peripheral portion of the hollow tube body on the proximal side of the electromagnetic probe, and the plurality of annular grooves have different predetermined distances relative to the probe head, which are used to indicate the length of the electromagnetic probe extending into the inner hole of the intramedullary nail, and can cooperate with the tool to provide a limiting function.

[0022] Optionally, the hollow tube body is made of a non-magnetic and highly elastic metal material, and the bearing member is made of plastic.

[0023] Optionally, the end of the carrying member is provided with a threaded hole for connecting with a tool, by means of which the carrying member can be inserted into the hollow tube body of the electromagnetic probe.

[0024] According to another aspect of the present invention, a surgical navigation system is provided, which is used to position an intramedullary nail and a locking hole of the intramedullary nail. The surgical navigation system includes a control device and the aforementioned electromagnetic probe, wherein the electromagnetic probe is suitable for inserting its probe head into the inner hole of the intramedullary nail to sense the position of the intramedullary nail and the locking hole with the aid of at least two sensors, and is connected to the control device through its coupling plug to provide the control device with stored position parameters associated with the probe head.

[0025] The electromagnetic probe according to the present invention has at least one or more of the following advantages:

[0026] 1. Able to smoothly pass through the curved intramedullary nail hole path;

[0027] 2. Ensure that the sensor at the front end of the probe is stably located at or near the locking hole;

[0028] 3. The two sensors can provide mutual calibration without the need for additional calibration tools;

[0029] 4. Two sensors are connected to one power plug, making operation convenient;

[0030] 5. It is equipped with features that facilitate the positioning and installation of two sensors, ensuring accurate installation positions;

[0031] 6. A special wire-locking feature is provided to prevent the core wire from being broken when plugging and unplugging the plug; and

[0032] 7. It can indicate the length of the probe inserted into the intramedullary nail and can be applied to intramedullary nails of different specifications. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The invention is described in detail below by way of non-limiting example with reference to the accompanying drawings, wherein the drawings are merely schematic and are not necessarily drawn to scale, and furthermore they show only those parts necessary for illustrating the invention, while other parts may be omitted or only briefly mentioned. That is, in addition to the parts shown in the drawings, the invention may also include other parts. In the various figures, similar elements or parts are indicated by the same reference numerals, wherein

[0034] Figure 1 is a schematic front view of an electromagnetic probe according to one embodiment of the present invention;

[0035] Figure 2 A Figure 1 A schematic perspective view of an intramedullary nail with an electromagnetic probe shown;

[0036] Figure 3 yes Figure 2 A schematic perspective view of the distal portion (front portion) of the intramedullary nail is shown;

[0037] Figure 4 yes Figure 1 A schematic cross-sectional view of the distal portion (front portion) of the electromagnetic probe shown;

[0038] Figure 5 yes Figure 2 A schematic perspective view of the proximal portion (posterior portion) of the intramedullary nail is shown;

[0039] Figure 6 yes Figure 1 A schematic cross-sectional view of the wire-stuck feature of the electromagnetic probe shown;

[0040] Figure 7a and Figure 7b They are Figure 1 A top view and a side view of the carrier member of the electromagnetic probe shown;

[0041] Figure 8 yes Figure 7a and Figure 7b A schematic perspective view of the load-bearing member shown;

[0042] Figure 9a, Figure 9b and Fig.10 3 are a schematic perspective view, a perspective cross-sectional view and a schematic cross-sectional view of a load-bearing member according to another embodiment of the present invention. DETAILED DESCRIPTION

[0043] The intramedullary electromagnetic probe according to an embodiment of the present invention is described below with reference to the accompanying drawings. In the following description, many specific details are set forth so that those skilled in the art can more fully understand the present invention. However, it is obvious to those skilled in the art that the present invention may be implemented without some of these specific details. In addition, it should be understood that the present invention is not limited to the specific embodiments described. On the contrary, it is contemplated that the present invention may be implemented with any combination of the following features and elements, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments and advantages are for illustrative purposes only and should not be regarded as elements or limitations of the claims unless explicitly stated in the claims.

[0044] Figure 1 The electromagnetic probe according to one embodiment of the present invention is schematically shown, which can be used as follows: Figure 2 The intramedullary nail 100 shown has an inner hole 102 extending longitudinally. Figure 1 As shown, the electromagnetic probe 1 may include a hollow body 10 extending along a longitudinal axis and a probe head 20 located at the distal end (ie, the end away from the operator) of the hollow body 10. The hollow body 10 may be made of a substantially non-magnetic and highly elastic metal material.

[0045] The probe head 20 may have a rounded head end, for example, the probe head 20 may have an arched or hemispherical head end. The size of the probe head 20 may match the size of the inner hole 102 of the intramedullary nail 100, and at the same time, the radial size of the probe head 20 may be greater than the outer diameter of the hollow tube 10. This ensures that the probe head 20 has sufficient rigidity to guide the electromagnetic probe 1 to be inserted into the inner hole of the intramedullary nail and to hold the sensor in a proper position, and on the other hand, the hollow tube 10 with a smaller outer diameter is conducive to improving the flexibility of the electromagnetic probe 1 and reducing resistance.

[0046] like Figure 2 As shown, the intramedullary nail 100 is slender, and its length dimension and inner hole curvature are both large. If the size of the probe tube body is consistent with the inner hole size of the intramedullary nail, it will cause difficulty in inserting the probe. If the size of the probe tube body is smaller than the inner hole size of the intramedullary nail, the probe head may shake near the locking hole and cause position difference, which will affect the sensing accuracy.

[0047] Since the electromagnetic probe 1 of the present invention adopts a probe head 20 with a rounded tip, and the size of the probe head 20 matches the size of the inner hole 102 of the intramedullary nail 100, the smooth probe head 20 can smoothly pass through the curved path of the inner hole 102. At the same time, the probe head 20 matching the size (aperture) of the inner hole 102 also helps to ensure that the sensor 30 located at the front end of the probe remains relatively still at or near the position of the locking hole 104, such as Figure 3 Better shown.

[0048] In addition, the electromagnetic probe 1 may further include at least two sensors 30 arranged in the hollow tube body 10 and bearing members 40, 40' for bearing the sensors 30. The bearing members 40, 40' may be made of plastic. Figure 1 In the illustrated embodiment, there are two sensors 30, which are separated by a predetermined distance in the longitudinal direction of the hollow tube 10. The carrying member 40 is suitable for carrying at least two sensors 30 and can be arranged adjacent to the probe head 20 or at least partially located in the probe head 20. The sensor 30 can be fixed in the carrying member 40 by adhesive bonding, for example.

[0049] See also Figure 1 and Figure 4 In this embodiment, the electromagnetic probe 1 is provided with a first electromagnetic sensor 30a and a second electromagnetic sensor 30b, and the two electromagnetic sensors are arranged in the bearing member 40 at a predetermined interval to ensure accurate installation of the sensors. In this embodiment, the two electromagnetic sensors 30a, 30b can be coaxially arranged on the bearing member 40 (i.e., the longitudinal axes of the two sensors are aligned). However, it is also conceivable that two or more electromagnetic sensors do not have to be coaxially arranged, as long as the respective position parameters are determined and recorded at the factory.

[0050] Figures 7a to 10 Two different load-bearing member embodiments are shown, and the similarities of the two embodiments are that the load-bearing members 40, 40' can have a spacing portion 42, 42' located in the middle thereof and groove portions 44, 44' arranged on both longitudinal sides of the spacing portion 42, 42', and the first electromagnetic sensor 30a and the second electromagnetic sensor 30b can be arranged in the grooves 48, 48' of the corresponding groove portions 44, 44', respectively. Thus, the spacing portions 42, 42' ensure that the two electromagnetic sensors 30a, 30b are separated by a predetermined distance. The two groove portions 44, 44' and their grooves 48, 48' can be configured to be symmetrically distributed about the spacing portions 42, 42'.

[0051] Since the two sensors are arranged at a predetermined spacing distance set at the factory, calibration can be provided. Therefore, there is no need to repeatedly plug and unplug the electromagnetic probe for confirmation after the magnetic field environment changes. The electromagnetic sensor of the present invention refers to an electromagnetic coil, which can perform position tracking in the formed magnetic field environment after power is turned on. If metal interference, magnetic field weakening, or magnetic source position changes are encountered, for a probe that only uses a single sensor, it cannot be guaranteed whether the position displayed by the computer corresponds to the actual position of the single sensor. For this, existing conventional operations usually require the use of other tools with other sensors for position calibration. Since the present invention is provided with at least two sensors separated by a predetermined spacing distance, the predetermined spacing distance can be stored in the computer software. When the distance calculated by the software based on the sensing position of these sensors differs from the predetermined spacing distance by more than a certain threshold, an alarm will be issued, so no additional calibration operation is required.

[0052] Although an example of an electromagnetic probe with two sensors is shown and described in these embodiments, it is also conceivable that the electromagnetic probe according to the present disclosure can be provided with more than two sensors, such as three or four or even more sensors. To this end, the bearing member can be provided with two or three or more spacing parts accordingly to separate three or four or more groove parts, and grooves for mounting sensors are formed in the groove parts, so that multiple sensors can be respectively arranged in corresponding groove parts separated by each spacing part.

[0053] exist Figures 7a to 8 In the illustrated embodiment, the bearing member 40 may be partially cylindrical (e.g., cylindrical in the middle and semi-cylindrical on both sides) and have a "T"-shaped longitudinal cross-section, the spacing portion 42 may protrude radially relative to the groove portion 44 to form a "T"-shaped middle protrusion, the spacing portion 42 may have a size adapted to the hollow portion of the hollow tube body 10, the groove portion 44 may be arranged on both sides of the middle protrusion to form a "T"-shaped top side extension, and the groove 48 may be configured as an open groove located in the top side extension and radially recessed from the surface of the groove portion 44 (see Figure 8 ).

[0054] A recess 420 may be provided at the outer peripheral portion of the bearing member 40 (specifically, the outer peripheral portion of the spacing portion 42) so that the core wire 60 connected to the sensor 30 can extend through the spacing portion via the recess 420 and connect to the coupling plug 50 (see Figure 1 ).

[0055] In addition, the end of the carrier member 40 facing away from the probe head 20 may be provided with a threaded hole 46 for connecting with a tool, by means of which the carrier member can be inserted into the hollow tube 10 of the electromagnetic probe.

[0056] like Figure 7a and Figure 8 As shown, the “T”-shaped middle protrusion formed by the spacing portion 42 may form a chamfer 422 on the side facing the probe head 20 , thereby facilitating the bearing member 40 to be smoothly inserted into the hollow tube 10 of the electromagnetic probe 1 .

[0057] exist Figures 9a to 10 In another embodiment shown, the bearing member 40' may be columnar (eg, cylindrical) and have a size adapted to fit the hollow portion of the hollow tube 10, and the groove 48' may be configured as an inner hole in the groove portion 44' (see Figure 9b ). Similar to Figures 7a to 8 In the embodiment, a longitudinally extending recess 420' is provided on the peripheral portion of the bearing member 40', and the core wire 60 connected to the sensor 30 can be at least partially arranged in the recess 420' (see Fig.10 ), a threaded hole 46' for connecting with a tool is formed in the end of the carrier member 40' (see Figure 9b ). Figures 7a to 8 In the embodiment, the chamfer 422' may be formed at one end of the bearing member 40' or at both side ends of the bearing member 40'.

[0058] Reference again Figure 1 The electromagnetic probe 1 may also include a single coupling plug 50, to which at least two sensors 30 are connected via respective core wires 60. This ensures convenient operation. A memory (not shown) for recording position parameters associated with the probe head 20 may also be provided in the coupling plug 50.

[0059] See also Figure 5 and Figure 6 According to the present embodiment, the electromagnetic probe 1 may further include a wire-fixing structure 70 located at the proximal end (ie, the end close to the operator) of the hollow tube body 10 for fixing the position of the core wire 60 connected to the sensor 30 .

[0060] like Figure 6 As shown, the wire clamping structure 70 includes at least two pins 72, 74, each of which has a slot (not shown) extending around its periphery. The core wire 60 can be at least partially positioned around the pins 72, 74 in the slot to prevent the core wire 60 from being pulled off when the coupling plug 50 is plugged in or out.

[0061] like Figure 1 , Figure 2 and Figure 5As shown, the electromagnetic probe 1 according to this embodiment may also include a plurality of annular grooves 12 arranged on the outer peripheral portion of the hollow tube body 10 at the proximal side of the electromagnetic probe (i.e., the side close to the operator), and the plurality of annular grooves 12 have respective different predetermined distances relative to the probe head 20. When a certain annular groove 12 is aligned with the proximal end surface of the intramedullary nail 100, the operator can be prompted that the electromagnetic probe 1 has been extended into the inner hole 102 of the intramedullary nail 100 by a length corresponding to the position of the annular groove 12, so it can be applicable to intramedullary nails of different specifications. In addition, the annular groove 12 can also cooperate with a tool (not shown) to provide a limit function.

[0062] The electromagnetic probe according to the present invention can be applied to, for example, a navigation system for intramedullary nail surgery to locate the intramedullary nail 100 and its locking hole 104. The surgical navigation system may include a control device not shown and the electromagnetic probe 1 as described above. The electromagnetic probe 1 can be inserted into the inner hole 102 of the intramedullary nail 100 through its probe head 20 to sense the position of the intramedullary nail 100 and the locking hole 104 by means of at least two sensors 30, and is connected to the control device through its coupling plug 50 to provide the stored position parameters to the control device.

[0063] When the electromagnetic probe leaves the factory, the coordinate system can be transferred to or defined at the center of the dome-shaped / hemispherical head end of the probe head 20, so the aforementioned position parameters are associated with the probe head 20. Specifically, the position parameters can indicate the relative position relationship between the center of the probe head 20 and the annular groove 12 in space, and the relative position relationship is associated with the anatomical curvature of the intramedullary nail 100. Therefore, the position parameters can include the length and curvature of each section between the center of the probe head 20 and the plurality of annular grooves 12. The intramedullary nail 100 is designed to have an angle / curvature in order to match the bone marrow cavity, so the curvature of intramedullary nails with different lengths also varies to a certain extent.

[0064] Those skilled in the art can understand that the embodiments described above are exemplary and can be improved by those skilled in the art. The structures described in various embodiments can be freely combined without causing conflicts in structure or principle.

[0065] After describing the preferred embodiments of the present invention in detail, those skilled in the art can clearly understand that various changes and modifications can be made without departing from the scope and spirit of the attached claims, and the present invention is not limited to the implementation methods of the embodiments described in the specification.

[0066] Reference numerals list

[0067] 100 Intramedullary nail

[0068] 102 inner hole

[0069] 104 Locking hole

[0070] 1 Electromagnetic probe

[0071] 10 hollow tube body

[0072] 12 Annular groove

[0073] 20 Probe head

[0074] 30 Sensors

[0075] 30a First electromagnetic sensor

[0076] 30b Second electromagnetic sensor

[0077] 40,40' load bearing member

[0078] 42,42' interval section

[0079] 420,420' recess

[0080] 422,422' Chamfer

[0081] 44,44' groove part

[0082] 46,46' threaded hole

[0083] 48,48' groove

[0084] 50 coupling plug

[0085] 60 core wire

[0086] 70 card line structure

[0087] 72,74 pins.

Claims

1. An electromagnetic probe for an intramedullary nail (100), characterized in that: The electromagnetic probe (1) comprises: A hollow tubular body (10) extending along a longitudinal axis; A probe head (20) located at the distal end of the hollow tubular body, the probe head having a rounded head end and a size matching the size of the inner hole of the intramedullary nail; at least two sensors (30) arranged in the hollow tube body and / or the probe head (20), the at least two sensors being separated by a predetermined distance in the longitudinal direction of the hollow tube body; and a carrying member (40, 40') adapted to carry the at least two sensors and arranged adjacent to the probe head (20) or at least partially in the probe head (20), The at least two sensors (30) include a first electromagnetic sensor (30a) and a second electromagnetic sensor (30b); the bearing member (40, 40') has a spacing portion (42, 42') and groove portions (44, 44') arranged on both longitudinal sides of the spacing portion; the first electromagnetic sensor and the second electromagnetic sensor can be respectively arranged in the grooves (48, 48') of the corresponding groove portions.

2. The electromagnetic probe according to claim 1, wherein: The radial dimension of the probe head (20) is greater than the outer diameter of the hollow tube body (10).

3. The electromagnetic probe according to claim 1, wherein: The probe head (20) has a dome-shaped or hemispherical head end.

4. The electromagnetic probe according to claim 1, wherein: The bearing member (40) is at least partially cylindrical and has a "T"-shaped longitudinal section, wherein the spacing portion (42) radially protrudes relative to the groove portion (44) to form a "T"-shaped middle protrusion, and the spacing portion (42) has a size adapted to the hollow portion of the hollow tube body (10), the groove portions (44) are arranged on both sides of the middle protrusion to form a "T"-shaped top side extension, and the groove (48) is configured as an open groove located in the top side extension and radially recessed from the surface of the groove portion (44).

5. The electromagnetic probe according to claim 1, wherein: The bearing member (40') is cylindrical and has a size adapted to fit into the hollow portion of the hollow tube (10), and the groove (48') is configured as an inner hole in the groove portion (44').

6. The electromagnetic probe according to claim 4 or 5, wherein: A longitudinally extending recess (420, 420') is provided on the outer peripheral portion of the bearing member (40, 40'), and a core wire (60) connected to the sensor (30) can be at least partially arranged in the recess.

7. The electromagnetic probe according to claim 4, wherein: The intermediate protrusion formed by the spacer portion (42) has a chamfer (422) on the side facing the probe head (20).

8. The electromagnetic probe according to claim 5, wherein: The end of the bearing member (40') has a chamfer (422').

9. The electromagnetic probe according to any one of claims 1 to 5, further comprising a single coupling plug (50), to which the at least two sensors are connected via respective core wires (60).

10. The electromagnetic probe according to claim 9, further comprising a memory disposed in the coupling plug (50) and used to record position parameters associated with the probe head (20).

11. The electromagnetic probe according to any one of claims 1 to 5, further comprising a wire-fixing structure (70) located at the proximal end of the hollow tube (10) for fixing the position of a core wire (60) connected to at least two sensors (30).

12. The electromagnetic probe according to claim 11, wherein: The wire clamping structure (70) includes at least two pins (72, 74), each pin having a slot extending around its periphery, and the core wire (60) is adapted to be at least partially positioned around the pins (72, 74) in the slot.

13. The electromagnetic probe according to any one of claims 1 to 5 further includes a plurality of annular grooves (12) arranged on the outer peripheral portion of the hollow tube body (10) on the proximal side of the electromagnetic probe (1), wherein the plurality of annular grooves have respective different predetermined distances relative to the probe head (20), and are used to indicate the length of the electromagnetic probe extending into the inner hole (102) of the intramedullary nail (100), and can cooperate with a tool to provide a limiting function.

14. The electromagnetic probe according to any one of claims 1 to 5, wherein: The hollow tube body (10) is made of a non-magnetic and highly elastic metal material, and the bearing component is made of plastic.

15. The electromagnetic probe according to any one of claims 1 to 5, wherein: The end of the carrier member (40, 40') is provided with a threaded hole (46, 46') for connecting with a tool, by means of which the carrier member can be inserted into the hollow tube (10) of the electromagnetic probe.

16. A surgical navigation system, the surgical navigation system being used for positioning an intramedullary nail (100) and a locking hole (104) of the intramedullary nail, characterized in that: The surgical navigation system comprises a control device and an electromagnetic probe according to any one of claims 1 to 15, wherein the electromagnetic probe (1) is suitable for being inserted into an inner hole (102) of an intramedullary nail (100) through its probe head (20) to sense the position of the intramedullary nail and the locking hole by means of at least two sensors (30), and being connected to the control device through its coupling plug (50) to provide the control device with stored position parameters associated with the probe head (20).

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