# US 8,784,425 B2 · Systems and methods for identifying landmarks on orthopedic implants

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- Number: US 8,784,425 B2
- Document ID: US8784425B2
- Status: Granted
- Kind: B2
- Application number: 12/547,716
- Filed: 2009-08-26
- Published: 2010-06-17
- Granted: 2014-07-22
- Earliest claimed: 2007-02-28
- Assignees: Smith & Nephew, Inc.
- Applicants: Nicholas S. Ritchey; Henry B. Faber; Nathaniel Kelley Grusin; James K. Rains; Gene Edward Austin; Tobias Schwägli; William M. Ricci
- Inventors: Nicholas S. Ritchey; Henry B. Faber; Nathaniel Kelley Grusin; James K. Rains; Gene Edward Austin; Tobias Schwägli; William M. Ricci
- Web page: https://patentgrep.com/patent/US8784425B2

## CPC

- A61B 17/1707: {using electromagnetic effects, e.g. with magnet and external sensors}
- A61B 5/05: Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves (measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24)
- A61B 5/06: Devices, other than using radiation, for detecting or locating foreign bodies {; Determining position of diagnostic devices within or on the body of the patient}
- A61B 5/062: {using magnetic field}
- A61B 5/1127: {using markers}
- A61B 17/1725: {for applying transverse screws or pins through intramedullary nails or pins}
- A61B 2034/2051: {Electromagnetic tracking systems}
- A61B 2034/2072: {Reference field transducer attached to an instrument or patient}
- A61B 2090/0813: {Accessories designed for easy sterilising, i.e. re-usable}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

Systems (10, 110, 1010, 1110) for identifying landmarks (31, 131, 1028, 1128) on orthopedic implants (30, 130, 1024, 1124) are disclosed. The systems (10, 110, 1010, 1110) include a field generator (16, 116, 1016, 1116) for generating a magnetic field and an orthopedic implant (30, 130, 1024, 1124) located within the magnetic field. The implant (30, 130, 1024, 1124) includes at least one landmark (31, 131, 1028, 1128), an optional removable probe (1029, 1129) and a first magnetic sensor (32, 132, 1026, 1126). The systems (10, 110, 1010, 1110) further include a landmark identifier (18, 118, 1016, 1116) with an optional second magnetic sensor (20, 120, 1020, 1120) and a processor (12, 112, 1012, 1112) for comparing sensor data from the first sensor (32, 132, 1026,1126) and second sensor (20, 120, 1020, 1120) or data from the first sensor (32, 132, 1026,1126) and landmark identifier (18, 118, 1016, 1116) using the set distance to calculate the position of the landmark identifier (18, 118, 1016, 1116) relative to the at least one landmark (31, 131, 1028,1128). The disclosed systems (10, 110, 1010, 1110) allow for blind targeting of one or more landmarks (31, 131, 1028, 1128).

## Claims

### Claim 1

A system for identifying a landmark, the system comprising:
a field generator for generating a magnetic field;
an orthopedic implant having at least one landmark, the orthopedic implant defining a cannulation and a longitudinal groove, the longitudinal groove having a proximal end region and a distal end region, wherein the orthopedic implant defines a first opening in an exterior surface of the orthopedic implant, the first opening being open to the longitudinal groove, and wherein, at a location adjacent the opening, the orthopedic implant defines a second opening to receive a cover for the first opening;
a cover that is insertable into the second opening such that the cover covers the first opening and is substantially flush with an external surface of the implant when disposed in the second opening;
a first magnetic sensor mounted to the orthopedic implant, the first magnetic sensor comprising one or more sensor coils disposed in a sensor housing, the first magnetic sensor being located in the distal end region of the longitudinal groove and being spaced apart from the at least one landmark a set distance, the first magnetic sensor being configured to produce sensor data responsive to the magnetic field;
a landmark identifier; and
a processor configured to analyze sensor data from the first magnetic sensor and data from the landmark identifier and use the set distance to calculate a position of the landmark identifier relative to the at least one landmark.

### Claim 2 (depends on 1)

The system of claim 1, wherein the landmark is selected from the group consisting of a structure, a void, a boss, a channel, a detent, a flange, a groove, a member, a partition, a step, an aperture, a bore, a cavity, a dimple, a duct, a gap, a notch, an orifice, a passage, a slit, a hole, or a slot.

### Claim 3 (depends on 1)

The system of claim 1, wherein the orthopedic implant is an intramedullary nail.

### Claim 4 (depends on 1)

The system of claim 1, wherein the orthopedic implant has an outer surface, an inner surface defining the cannulation, and a wall therebetween, and the first magnetic sensor is mounted within the wall.

### Claim 5 (depends on 1)

The system of claim 1, wherein the orthopedic implant further comprises a pocket and the first magnetic sensor is located within the pocket.

### Claim 6 (depends on 1)

The system of claim 1, further comprising an insertion handle removably coupled to the orthopedic implant.

### Claim 7 (depends on 1)

The system of claim 1, further comprising a monitor electrically coupled to the processor.

### Claim 8 (depends on 1)

The system of claim 1, wherein the longitudinal groove is disposed along an outer surface of the implant.

### Claim 9 (depends on 1)

The system of claim 1, wherein the longitudinal groove is generally adjacent the cannulation.

### Claim 10 (depends on 9)

The system of claim 9, further comprising a removable lead coupled to the first magnetic sensor.

### Claim 11 (depends on 1)

The system of claim 1, wherein the landmark identifier comprises a drill sleeve.

### Claim 12 (depends on 1)

The system of claim 1, wherein the landmark identifier further comprises a serrated tip.

### Claim 13 (depends on 1)

The system of claim 1, wherein the processor provides feedback information to a user.

### Claim 14 (depends on 1)

The system of claim 1, wherein the field generator and landmark identifier are disposed within a common handheld housing.

### Claim 15 (depends on 1)

The system of claim 1, wherein the orthopedic implant has an inner surface that defines the cannulation, and the longitudinal groove is defined in the inner surface.

### Claim 16 (depends on 1)

The system of claim 1, wherein at least one end of the cannulation ends at an opening defined in an exterior surface of the orthopaedic implant.

### Claim 17 (depends on 1)

The system of claim 1, wherein the longitudinal groove is offset from the cannulation such that the magnetic sensor is located at least partially outside the cannulation.

### Claim 18 (depends on 1)

The system of claim 1, wherein the longitudinal groove extends from the distal end region of the orthopaedic implant to a proximal end of the orthopaedic implant.

### Claim 19

A system for identifying a landmark, the system comprising:
a field generator for generating a magnetic field;
an orthopedic implant located within the magnetic field, the orthopedic implant having at least one landmark, the orthopedic implant defining an internal cannulation and a longitudinal groove that extends generally adjacent the cannulation, the longitudinal groove having a proximal end region and a distal end region, the longitudinal groove being defined in a wall of the orthopedic implant between an outer surface of the wall and an inner surface of the wall that defines the cannulation, wherein the longitudinal groove has a diameter and is located in the wall of the orthopedic implant such that the diameter is contained between the outer surface and the inner surface;
an insertion handle removably attached to the orthopedic implant;
a first magnetic sensor placed within the orthopedic implant at the distal end portion of the longitudinal groove and spaced apart from the at least one landmark a set distance;
a landmark identifier; and
a processor for comparing sensor data from the first sensor and landmark identifier using the set distance to calculate the position of the landmark identifier relative to the at least one landmark, wherein communication or power leads are routed to the first magnetic sensor through the insertion handle.

### Claim 20 (depends on 19)

The system of claim 19, wherein the field generator and landmark identifier are disposed within a common handheld housing.

### Claim 21 (depends on 19)

The system of claim 19, wherein communication and power leads are routed to the first magnetic sensor through the insertion handle.

### Claim 22

A system for identifying a landmark, the system comprising:
a field generator for producing a set of multiple different magnetic field distributions;
an orthopedic implant having at least one landmark, the orthopedic implant defining an internal cannulation and a longitudinal groove that extends generally adjacent the cannulation, the longitudinal groove having a proximal end region and a distal end region, the longitudinal groove being defined in a wall of the orthopedic implant between an outer surface of the wall and an inner surface of the wall that defines the cannulation, the longitudinal groove being closed to the cannulation wherein the longitudinal groove has a diameter and is located in the wall of the orthopedic implant such that the diameter is contained between the outer surface and the inner surface;
a first magnetic sensor mounted to the orthopedic implant, the first magnetic sensor being located in the distal end region of the longitudinal groove and being spaced apart from the at least one landmark a set distance, the first magnetic sensor being configured to produce sensor data responsive to the magnetic field;
a removable lead coupled to the first magnetic sensor, the removable lead being disposed in the longitudinal groove and extending from a proximal end of the orthopaedic implant;
a landmark identifier; and
a processor configured to analyze sensor data from the first magnetic sensor and data from the landmark identifier and use the set distance to calculate a position of the landmark identifier relative to the at least one landmark.