Retrograde femoral intramedullary nail, and related systems and methods

Patent metadata

Field	Value
Publication number	US-12004785-B2
Application number	US-202217725865-A
Country	US
Kind code	B2
Filing date	Apr 21, 2022
Priority date	Apr 21, 2022
Publication date	Jun 11, 2024
Grant date	Jun 11, 2024

Abstract

A retrograde intramedullary nail for insertion in the medullary canal of a femur includes a body that is elongate and defines a leading end and a trailing end spaced from each other at a length sufficient to extend from an intercondylar region at least to a subtrochanteric region of the femur. The body further defines a leading portion that extends to the leading end. The leading portion defines at least one locking hole configured to receive a fixation member. The at least one locking hole defines a central hole axis that is oriented to extend through the neck and head of the femur.

First claim

What is claimed:

1. A retrograde intramedullary nail for retrograde insertion in the medullary canal of a femur, comprising:
a body that is elongate and defines a leading end and a trailing end spaced from each other at a length sufficient to extend from an intercondylar region of the femur at least to a subtrochanteric region of the femur, the body further defining a leading portion that extends to the leading end,
wherein the leading portion defines at least one locking hole configured to receive a fixation member, wherein the at least one locking hole defines a central hole axis, and the leading portion is configured such that the central hole axis extends through the neck of the femur and intersects the head of the femur, and
wherein the body defines,
an exterior surface having a primary surface portion that is substantially cylindrical within the leading portion; and
at least one relief formation that deviates from the primary surface portion and is configured to reduce stress concentrations in the leading portion, wherein the at least one relief formation comprises a plurality of annular protrusions that extend outwardly from the primary surface portion.

2. The retrograde intramedullary nail of claim 1 , wherein the at least one locking hole intersects at least one of the plurality of annular protrusions, the body adjacent a periphery of the at least one locking hole defines first and second recesses defining a bump therebetween along the periphery.

3. The retrograde intramedullary nail of claim 1 , wherein the plurality of annular protrusions define respective cross-sectional dimensions that are greater than a cross-sectional dimension of the primary surface portion within the leading portion by a factor in a range from 1.001 to about 1.250.

4. The retrograde intramedullary nail of claim 3 , wherein a trailing-most one of the plurality of annular protrusions is spaced from the leading end by a distance is in a range from about 7.5 mm to about 100 mm.

5. The retrograde intramedullary nail of claim 1 , wherein the body further defines:
a trailing portion that extends to the trailing end; and
an intermediate portion that extends between the trailing and leading portions,
wherein the primary surface portion defines a first diameter within the intermediate portion and a second diameter within the trailing portion, wherein the second diameter is greater than the first diameter.

6. The retrograde intramedullary nail of claim 1 , wherein the at least one locking hole comprises two locking holes each extending through the body along respective central hole axes that are each substantially parallel with the head-neck axis of the femur.

7. The retrograde intramedullary nail of claim 1 , wherein the body defines internal threads within the at least one locking hole, and the internal threads are configured to engage complementary external threads at a head of the fixation member for threaded fixation of the at least one fixation member to the retrograde intramedullary nail.

8. The retrograde intramedullary nail of claim 7 , wherein the at least one locking hole extends through the body along at least one respective hole axis, and the body defines, within the at least one locking hole, a plurality of columns circumferentially spaced from each other around the hole axis by a plurality of recesses, the internal threads traverse the plurality of columns, and the plurality of columns are configured for variable-angle insertion of the fixation member through the at least one locking hole.

9. A system for femoral fixation, comprising:
an intramedullary nail having a body that is elongate and defines a leading end and a trailing end spaced from each other at a length sufficient to extend from an intercondylar region of the femur at least to a subtrochanteric region of the femur, wherein a leading portion of the body extends to the leading end and defines 1) at least one locking hole configured to receive at least one fixation member for affixing the leading portion to the femur, and 2) at least one relief formation configured to reduce stress concentrations in the leading portion, the body further defining an exterior surface having a primary surface portion that is substantially cylindrical within the leading portion, wherein the at least one relief formation deviates from the primary surface portion and comprises a plurality of annular protrusions that extend outwardly from the primary surface portion; and
an aiming assembly configured to connect to the leading portion and insert at least one fixation member through the at least one locking hole.

10. The system of claim 9 , wherein:
the leading portion defines two or more coupling apertures positioned astride the at least one locking hole with respect to a longitudinal direction of the intramedullary nail; and
the aiming assembly comprises:
two or more guide wires for insertion within the two or more coupling apertures; and
an aiming block having 1) two or more guide slots for guiding translation of the aiming block along the two or more guide wires, and 2) at least one aiming channel for guiding movement of the at least one fixation member toward the at least one locking hole.

11. The system of claim 10 , wherein the at least one targeting hole is located between the two or more guide slots along a direction parallel to the longitudinal direction.

12. The system of claim 10 , further comprising two or more guide sleeves insertable along the two or more guide slots, wherein the two or more guide sleeves each define a central bore sized for insertion of the respective guide wire therethrough.

13. The system of claim 10 , further comprising an insertion device insertable through the at least one aiming channel, wherein the insertion device is configured to insert at least one fixation member through the at least one locking hole in the leading portion of the nail body.

14. The system of claim 13 , wherein:
the at least one locking hole comprises first and second locking holes spaced from each other at a hole spacing distance along the longitudinal direction;
the at least one fixation member comprises a first fixation member and a second fixation member;
the at least one aiming channel of the guide block comprises first and second aiming channels spaced from each other at a spacing distance equivalent to the hole spacing distance; and
the insertion device is configured to extend, selectively and sequentially, through each of the first and second aiming channels, and the insertion device is further configured to 1) advance the first fixation member through the first aiming channel and subsequently through cortical bone tissue on a near side of the first locking hole, through the first locking hole, and subsequently into cortical bone tissue on a far side of the first locking hole, and 2) advance the second fixation member through the second aiming channel and subsequently through cortical bone tissue on a near side of the second locking hole, through the second locking hole and subsequently into cortical bone tissue on a far side of the second locking hole.

Assignees

• Depuy Synthes Products Inc

Inventors

• Shinde Rohit
• Keyer Thomas
• Cowens David
• Mcmanus Joshua
• Schmitt Raymond
• Bushelow Michael
• Kmiec Jr Stanley J
• Gabelberger Josef

Classifications

• A61B17/744 Primary

  the longitudinal elements coupled to an intramedullary nail · CPC title

• A61B17/1725

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

• A61B17/1721

  for applying pins along or parallel to the axis of the femoral neck · CPC title

• A61B17/7208

  Flexible pins, e.g. ENDER pins · CPC title

• A61B17/7283

  with special cross-section of the nail · CPC title