Intramedullary anchor for interphalangeal arthrodesis

Patent metadata

Field	Value
Publication number	US-2016338747-A1
Application number	US-201414420260-A
Country	US
Kind code	A1
Filing date	Dec 19, 2014
Priority date	Dec 19, 2014
Publication date	Nov 24, 2016
Grant date	—

Abstract

An intramedullary implant has opposite ends inserted into bores in abutting phalanges for correcting hammer toe and for similar arthrodesis procedures. A rear end of the implant may be threaded and is received in a bore in the proximal phalanx. A front end has an asymmetric pointed shape with longitudinally and/or angularly spaced rear-facing gripping flukes. The pointed front end is received in the middle phalanx. The asymmetric pointed shape is self-aligning, enabling entry to begin without first longitudinally aligning the bones. The rear end when screwed into place can be rotated to select the orientation of the asymmetric pointed shape. The pointed front end is inserted and pushed to bring the phalanges into abutment where the implant holds them against retraction or rotational displacement.

First claim

What is claimed is:

1 . An intramedullary implant, comprising;
an implant body with an anchor end facing along a longitudinal axis, the anchor being configured for insertion in one direction into a bore in a bone for gripping sides of the bore, and resisting retraction of the intramedullary implant from the bone in an opposite direction; wherein the anchor has an anchor head at a leading end of the implant body and surfaces tapering outward and rearward at angles from the point, to respective gripping flukes spaced back from the leading end; wherein at least two said surfaces are at least one of angularly and longitudinally spaced from one another relative to the axis, and taper outward and rearward to respective said gripping flukes at least with one of different angles and different radial spans.

2 . The implant of claim 1 , wherein the respective gripping flukes of the diametrically opposite surfaces are at different longitudinal distances from the point at the leading end.

3 . The implant of claim 2 , wherein at least one of the gripping flukes that is closer to the leading end has a greater angle of outward and rearward taper than at least one of the gripping flukes that is farther from the point at the leading end.

4 . The implant of claim 1 , wherein a diametrical span between the respective gripping flukes of the diametrically opposite surfaces is greater than an internal diameter of the bore, whereby the gripping flukes engage opposite sidewalls of the bore.

5 . The implant of claim 1 , wherein the implant forms at least part of a prosthesis for arthrodesis of an inter-phalangeal joint and is configured for engagement of both phalanges abutting at said joint.

6 . The implant of claim 5 , wherein the end opposite from the leading end is threaded.

7 . A method for surgical repair of an interphalangeal joint, comprising:
forming a bore along a longitudinal bore axis in at least one phalanx at the joint; providing an intramedullary support including an implant body with an anchor end facing along a longitudinal axis, wherein the anchor end has an anchor head having a point at a leading end and outer surfaces tapering outward and rearward at different angles; wherein at least one of the outer surfaces leads to a gripping fluke that is configured to grip in a direction opposite from the leading end; orienting the longitudinal axis of the intramedullary support oblique to the longitudinal bore axis and moving the leading end of the intramedullary support into the bore; advancing the anchor end into the bore, thereby bringing the longitudinal axis of the intramedullary support into alignment with the bore axis; and continuing to advance the anchor end into the bore to an end position at which the gripping fluke engages the bore to prevent retraction.

8 . The method of claim 7 , further comprising inserting an end opposite from the leading end into a second phalanx and rotationally aligning the intramedullary support such that the different angles are oriented parallel to a sagittal plane, prior to moving the leading end into the bore.

9 . The method of claim 7 , wherein the end opposite from the leading end is threaded, wherein said inserting of the end opposite from the leading end comprises screwing the intramedullary support into the second phalanx.

10 . The method of claim 7 , wherein the implant body has a threaded shaft and further comprising screwing the threaded shaft into the second phalanx leaving the anchor end to protrude beyond the second phalanx.

11 . The method of claim 10 , further comprising rotating the threaded shaft to selectively place the outer surfaces in position for guiding along the edge of the bore.

Assignees

• Wright Medical Tech Inc

Inventors

• Shemwell Jessica L
• Branthover Pearce

Classifications

• A61F2002/4228

  for interphalangeal joints, i.e. IP joints · CPC title

• A61B17/7233

  with special means of locking the nail to the bone · CPC title

• A61B17/7291 Primary

  for small bones, e.g. in the foot, ankle, hand or wrist · CPC title

• A61B17/7283

  with special cross-section of the nail · CPC title

• A61B2017/681

  Alignment, compression, or distraction mechanisms · CPC title