Medical pin removal tool

Patent metadata

Field	Value
Publication number	US-11389222-B2
Application number	US-202016793725-A
Country	US
Kind code	B2
Filing date	Feb 18, 2020
Priority date	Feb 18, 2020
Publication date	Jul 19, 2022
Grant date	Jul 19, 2022

Abstract

A cylindrical shaft may be gripped with an apparatus including a housing having an axis and an inner surface with multiple asymmetric cam surfaces, a proximal end including a means to rotate the housing, and a distal end having an opening configured to receive the cylindrical shaft, at least two cylindrical gripping members configured to grip the cylindrical shaft, where each cylindrical gripping member contacts a corresponding asymmetric cam surface at a first rest position, and a rotatable frame which holds each pair of cylindrical gripping members at a fixed angular orientation relative to each other. The rotatable frame is configured to rotate upon insertion of the cylindrical shaft into a space defined by the gripping members so that each gripping member moves away from the axis of the housing along a first portion of the corresponding asymmetric cam surface. After insertion of the cylindrical shaft, the housing is configured to rotate so as to cause each gripping member to move toward the axis of the housing along the corresponding asymmetric cam surface.

First claim

What is claimed is:

1. An apparatus for gripping a cylindrical shaft, comprising:
a housing having an axis and an inner surface with multiple asymmetric cam surfaces, a proximal end comprising a means to rotate the housing, and a distal end having an opening configured to receive the cylindrical shaft,
at least two gripping members configured to apply a deforming force to the cylindrical shaft, where each gripping member comprises:
a spherical gripping member contacting a corresponding one of the asymmetric cam surfaces at a first rest position, and
a second gripping member, the second gripping member being coaxial with the spherical gripping member; and

a rotatable frame which holds each pair of the gripping members at a fixed angular orientation relative to each other,
wherein:
the rotatable frame is biased into a first position relative to the housing where each said spherical gripping member and each said second gripping member contact a first portion of the corresponding one of the asymmetric cam surfaces at the first rest position;
the rotatable frame is configured to rotate in a first direction relative to the housing upon insertion of the cylindrical shaft into a space defined by the spherical gripping members so that each said gripping member moves away from the axis of the housing along the first portion of the corresponding one of the asymmetric cam surfaces; and
after insertion of the cylindrical shaft, the rotatable frame is configured to rotate in a second direction relative to the housing so as to cause each said spherical gripping member to apply the deforming force by moving toward the axis of the housing along a second portion of the corresponding one of the asymmetric cam surfaces.

2. The apparatus of claim 1 , wherein the rotatable frame is biased into the first position by a torsion spring within the rotatable frame, wherein the torsion spring engages the housing; and
rotation of the rotatable frame relative to the housing disengages the torsion spring from the housing.

3. The apparatus of claim 1 , wherein each said coaxial second gripping member is independently selected from the group consisting of a spherical gripping member, a right cylindrical gripping member having planar ends, and a cylindrical gripping member having non-planar ends.

4. The apparatus of claim 3 , wherein each said second gripping members is a cylindrical gripping member.

5. The apparatus of claim 4 , wherein each said second gripping member is a cylindrical gripping member having non-planar ends.

6. The apparatus of claim 5 , wherein each said second gripping member is a cylindrical gripping member having frustoconical ends, dome shaped ends, or a combination thereof.

7. The apparatus of claim 1 , wherein each said spherical gripping member is made of a material which is harder than the cylindrical shaft, where the material is selected from the group consisting of silicon nitride, zirconium oxide, silicon carbide, and stainless steel.

8. The apparatus of claim 1 , wherein:
each pair of adjacent ones of the asymmetric cam surfaces is connected by a substantially planar surface,
the first portion of each of the asymmetric cam surfaces has a first curvature, and
the second portion of each of the asymmetric cam surfaces has a second curvature which is greater than the first curvature.

9. The apparatus of claim 1 , wherein the means to rotate the housing comprises a handle.

10. The apparatus of claim 1 , wherein the means to rotate the housing comprises a shaft having a first planar surface, the shaft being configured to engage a handle with a bore having a corresponding second planar surface, the shaft having a groove therein, the groove being configured to engage a ball bearing mounted in the bore.

11. The apparatus of claim 1 , wherein the means to rotate the housing comprises a hexagonal shaft configured to engage a handle with a hexagonal bore, the hexagonal shaft having a groove therein, the groove being configured to engage a ball bearing mounted in the hexagonal bore.

12. A method for removing a cylindrical shaft from a material using the apparatus of claim 1 , comprising:
inserting the cylindrical shaft into the opening at the distal end of the housing when each said spherical gripping member contacts the first portion of the corresponding one of the asymmetric cam surfaces at the first rest position;
pushing the cylindrical shaft into the space defined by the spherical gripping members so as to cause each said spherical gripping member to move away from the axis of the housing along the first portion of the corresponding one of the asymmetric cam surfaces, thereby expanding the space defined by the spherical gripping members until it accepts the cylindrical shaft;
after insertion of the cylindrical shaft, rotating the housing relative to the rotatable frame so as to cause each gripping member to move toward the axis of the housing along the second portion of the corresponding one of the asymmetric cam surfaces until the cylindrical shaft is gripped and deformed by the spherical gripping members; and
removing the deformed shaft from the from the material.

13. The method of claim 12 , wherein the cylindrical shaft is a surgical pin, and the material is bone.

Assignees

• Depuy Synthes Products Inc

Inventors

• Wahl Michael

Classifications

• A61B17/8872

  Instruments for putting said fixation devices against or away from the bone (A61B17/7074, A61B17/808 take precedence) · CPC title

• A61B17/162 Primary

  Chucks or tool parts which are to be held in a chuck · CPC title

• A61B17/8886 Primary

  holding the screw head · CPC title

• B25B13/5066

  using rollers moving along radial cams in a cage structure at least partially surrounding the pipe · CPC title

• A61B17/861

  specially shaped for gripping driver · CPC title