System and method for identifying a landmark

Patent metadata

Field	Value
Publication number	US-9775649-B2
Application number	US-201113323010-A
Country	US
Kind code	B2
Filing date	Dec 12, 2011
Priority date	Feb 28, 2008
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A system ( 1010, 1110 ) for identifying a landmark is disclosed. The system includes a field generator ( 1016, 1116 ) for generating a magnetic field, an orthopedic implant ( 1030, 1130 ) located within the magnetic field, the implant having at least one landmark ( 1028, 1128 ), a removable probe ( 1029, 1129 ) with a first magnetic sensor ( 1026, 1126 ), a landmark identifier ( 1016, 1116 ) with a second magnetic sensor ( 1020, 1120 ) and a processor ( 1012, 1112 ) for comparing sensor data from the first and second sensor and using the set distance to calculate the position of the landmark identifier relative to the at least one landmark. The system allows for blind targeting of one or more landmarks.

First claim

What is claimed is:

1. A probe for guiding placement of an identifier relative to an orthopaedic implant, comprising:
an elongated element that includes an anti-rotation feature, the anti-rotation feature comprising a non-circular cross-sectional geometry of at least a portion of the elongated element,
wherein the elongated element is configured to engage a stop at any of a plurality of points along a length of the elongated element,
wherein the elongated element comprises a plurality of detents,
wherein at least a portion of the elongated element has a longitudinal axis that has a natural curvature, and
wherein the elongated element is configured to limit rotation of the elongated element relative to the stop when the elongated element is received through a slot in the stop; and

a magnetic sensor coupled to the elongated element.

2. The probe of claim 1 , wherein:
the elongated element has a proximal end and a distal end;
the magnetic sensor is coupled to the distal end of the elongated element; and
the elongated element is a flexible elongated element.

3. The probe of claim 1 , wherein the anti-rotation feature comprises the elongated element having a cross-section perpendicular to the longitudinal axis that is at least one of rectangular, oval, or square.

4. The probe of claim 1 , wherein the detents in the plurality of detents correspond to particular insertion depths of the elongated element within a channel of the orthopaedic implant.

5. The probe of claim 4 , wherein one of the detents indicates a position on the elongated element corresponding to an appropriate depth of insertion of the elongated element to target a landmark of an orthopaedic implant having a particular length.

6. The probe of claim 1 , wherein the elongated element has a longitudinal extent from the magnetic sensor to a proximal end where the elongated element terminates, and the non-circular cross-sectional geometry of the elongated element extends continuously along the entire longitudinal extent of the elongated element.

7. The probe of claim 1 , wherein the anti-rotation feature is configured to limit rotation of the elongated element within a cannulation having a circular cross-section.

8. The probe of claim 1 , wherein the orthopaedic implant is an intramedullary nail having a particular length, and at least one of the plurality of detents on the elongated element indicates a position on the elongated element corresponding to an appropriate depth of insertion of the elongated element to target a landmark of the intramedullary nail having the particular length.

9. The probe of claim 1 , further comprising a memory device storing calibration data for the magnetic sensor.

10. The probe of claim 1 , wherein at least one of the plurality of the detents is located at a position where a length of the elongated element between the stop and the magnetic sensor is dimensioned to place the magnetic sensor at a known placement relative to a landmark of the orthopaedic implant when the probe is inserted into a channel of the orthopaedic implant.

11. The probe of claim 10 , wherein, when the stop is at the indicated position, the length of the elongated element between the stop and the magnetic sensor is dimensioned to place the magnetic sensor at the known placement when the stop engages an end of the orthopaedic implant.

12. The probe of claim 10 , wherein, when the stop is at the indicated position, the length of the elongated element between the stop and the magnetic sensor is dimensioned to place the magnetic sensor at the known placement when the stop engages a particular portion of an insertion handle that is separate from the probe.

13. The probe of claim 12 , wherein the length of the elongated element is dimensioned such that, in the known placement of the magnetic sensor, the elongated element extends through a channel of the insertion handle and extends into the channel of the orthopaedic implant, the elongated element being movable through the channel of the insertion handle.

14. The probe of claim 10 , wherein, when the stop is at the indicated position, the length of the elongated element between the stop and the magnetic sensor is dimensioned such that, in the known placement of the magnetic sensor, the magnetic sensor is aligned with a hole defined in the orthopaedic implant or is aligned adjacent to the hole.

15. The probe of claim 1 , wherein the probe has a metal exterior along the elongated element.

16. The probe of claim 1 , wherein the plurality of detents are spaced apart along the length of the elongated element, and wherein the elongated element has the non-circular cross-sectional geometry extending over a region of the elongated element that includes the plurality of detents.

17. The probe of claim 1 , wherein the elongated element is formed of metal and forms at least a portion of the exterior of the probe.

18. A system comprising:
an orthopaedic implant having a landmark and a channel with a proximal region having a circular cross-section, the channel having a proximal end;
a landmark identifier;
a probe configured to be inserted into the proximal end of the channel, the probe including a magnetic field sensor and an elongated element configured to place the magnetic field sensor at a known placement relative to the landmark when the probe is inserted in the channel of the orthopaedic implant, at least a portion of the elongated element having a longitudinal axis that has a natural curvature, and the elongated element including an anti-rotation feature configured to limit rotation of the elongated element at the region having the circular cross-section, wherein the anti-rotation feature of the probe comprises a non-circular cross-sectional geometry of at least a portion of the elongated element, the anti-rotation feature being configured to limit rotation of the elongated element when the probe extends into the proximal end of the channel and into the proximal region having the circular cross-section;
a stop that is adjustable along a length of the elongated element, wherein the stop defines a slot and is configured engage the non-circular cross-sectional geometry of the elongated element to limit rotation of the elongated element while the elongated element is received in the slot, the stop being configured to engage the proximal end of the orthopaedic implant; and
a control unit operably connected to the landmark identifier and the magnetic field sensor,
the system configured such that with the sensor of the probe located in the channel of the orthopaedic implant and positioned at a predetermined position relative to the landmark, the system can be utilized to guide the placement of the landmark identifier relative to the landmark.

19. The system of claim 18 , wherein the stop comprises an alignment feature configured to engage the orthopaedic implant or an insertion handle to limit rotation of the stop relative to the orthopaedic implant; and
wherein the stop has a hole defined through the stop, the hole being offset from the slot.

20. The system of claim 18 , wherein the stop comprises a locking mechanism configured to adjustably maintain the position of the stop along the length of the elongated element.

21. The system of claim 18 , wherein the orthopaedic implant is an intramedullary nail, and wherein the elongated element is a flexible elongated element.

22. The system of claim 18 , wherein the elongated element comprises a metal tape, and wherein the anti-rotati

Assignees

• Rains James K
• Ritchey Nicholas S
• Austin Gene Edward
• Grusin Nathaniel Kelley
• Janna Sied W
• Heotis Charles C
• Smith & Nephew Inc

Inventors

• Rains James K
• Ritchey Nicholas S
• Austin Gene Edward
• Grusin Nathaniel Kelley
• Janna Sied W
• Heotis Charles C

Classifications

• A61B17/1707

  using electromagnetic effects, e.g. with magnet and external sensors · CPC title

• A61B2090/3958

  emitting a signal · CPC title

• A61B5/064 Primary

  using markers (A61B5/062 takes precedence) · CPC title

• A61B2090/397

  electromagnetic other than visible, e.g. microwave · CPC title

• A61B17/1725

  for applying transverse screws or pins through intramedullary nails or pins · CPC title