Fasteners and fastener delivery devices for affixing sheet-like materials to bone or tissue
A fastener for attaching a sheet-like implant to tissue or bone may be provided with a first arm having a proximal end and a distal end, a second arm having a proximal end and a distal end, and a bridge extending therebetween. Each of the first and second arms include a trunk portion defining at least a portion thereof, the trunk portion having a lateral extent larger than a lateral extent of the bridge or non-trunk portion of the arm adjacent thereto and can be mounted eccentrically to the bridge or non-trunk portion of the arm adjacent thereto such that the staple includes a first change in lateral stiffness disposed proximate the bridge or non-trunk portion of the arm abutment with the trunk. Fastener delivery devices and methods are also disclosed.
1. A fastener for attachment to tissue or bone comprising:
a first arm having a proximal end and a distal end;
a second arm having a proximal end and a distal end;
a bridge connecting the first arm and second arm;
each of the first arm and the second arm including a trunk portion extending along at least a portion thereof, each trunk portion having a lateral extent larger than a lateral extent of the bridge and the non-trunk portion of the first arm or the second arm; and
each trunk portion including a first projection and a second projection, the first projection extending away from the trunk portion in a first direction such that a first moment is applied to the trunk in response to a pullout force on the bridge, the second projection extending away from the trunk portion in a second direction such that a second moment is applied to the trunk in response to a pullout force on the bridge,
wherein each trunk portion comprises an area of reduced lateral stiffness located between a first portion of each trunk portion and a second portion of each trunk portion.
2. The fastener of claim 1 , wherein the change in lateral stiffness allows flexing of each trunk portion in response to at least one of the first and second moments.
3. The fastener of claim 2 , wherein the direction of the first moment is generally opposite the direction of the second moment on each arm.
4. The fastener of claim 1 , wherein the first direction extends proximally and laterally away from each trunk, the second direction extends proximally and laterally away from the each trunk and a lateral component of the second direction is generally opposite a lateral component of the first direction.
5. The fastener of claim 1 , wherein each trunk portion defines a cavity, each cavity being spaced laterally from the non-trunk portion or bridge adjacent to each trunk portion, and the cavity defined by each trunk portion is sized to receive a stake of a fastener delivery device.
6. The fastener of claim 5 , wherein each cavity defined by each trunk portion extends from a proximal end to a distal end of each trunk portion.
7. The fastener of claim 1 , wherein the first arm, the second arm and the bridge are integrally formed of a polymeric material.
8. The fastener of claim 7 , wherein the polymeric material comprises a polyether ether ketone (PEEK) material.
9. The fastener of claim 1 , wherein the lateral extent of each trunk portion in at least one direction is at least about three times the lateral extent of at least a portion of the bridge or non-trunk portion of the first arm or the second arm.
10. The fastener of claim 9 , wherein the lateral extent of at least a portion of the bridge and non-trunk portion of the first arm or the second arm is about 0.3 mm to about 3.0 mm.