Staples for bone fixation

A method of increasing a length span of a staple, which includes the steps of:

• employing prongs which define a z-axis of an x;y;z coordinate system, generally parallel with their longitudinal axis;
• mounting the staple on a staple receptor, which is arranged on the first prong, and which defines an x-axis of the x;y;z coordinate system, parallel with a length direction of the staple;
• and
• sliding a thin cam, arranged on a second prong, and having a width which increases in the direction of increasing y, between the staple receptor and the staple mounted thereon, thus wedging the thin cam between the staple receptor and the staple;
• and
• plastically deforming the staple, to increase its length span.

A staple for bone fixation, formed of a shape-memory alloy having a fully martensitic phase within a first temperature range, and having a fully austenitic phase within a second temperature range, which is higher than the first temperature range, which includes:

• a web having a first length span and a thickness;
• two bending points, forming the end points of said web;
• and
• two semicircular end sections, beginning from said bending points, having a radius of curvature (R1), an angle of curvature (α) that is greater than 90°, and a thickness (t) which is substantially the same as said web thickness,
• wherein by plastically deforming said staple, reversibly, in the fully martensitic phase, to decrease said angle of curvature (α) to 90°, said semicircular end sections are straightened, to facilitate insertion into the bone, and said length span may be increased to a desired value,
• wherein the plastic deformation strain δ for different ratios of R1/t does not exceed 15% in the fully martensitic phase,
• and wherein upon transformation to its austenitic shape, said staple generally resumes its original shape, but with a second length span that is greater than said first length span.

A method of bone fixation, which includes the steps of:

• drilling at least one pair of bores across a fracture interface of a bone;
• measuring the distance span between the two bores of the bore pair;
• employing a staple for bone fixation, formed of a shape-memory alloy having a fully martensitic phase within a first temperature range, and having a fully austenitic phase within a second temperature range, which is higher than the first temperature range, which includes:
• a web having a length span;
• and
• two semicircular end sections, having angles of curvature that are greater than 90°;
• plastically deforming the staple, reversibly, in its martensitic phase, to simultaneously decrease said angle of curvature to 90°, thus straightening the semicircular end sections, to facilitate insertion into the bone, and to increase the length span of the web to a desired value;
• inserting the staple into the bores;
• and
• employing the staple in a partially plastically deformed state, resulting from the length-span increase.

A system for increasing a length span of a staple, which includes:

• a) a staple formed of a shape memory alloy;
• and
• b) an apparatus for increasing a length span of a staple, wherein said apparatus includes:
• proximal and distal ends with respect to a user, which define a z-axis of an x;y;z coordinate system between them;
• and
• first and second prongs, joined by a system which provides a mechanical advantage to selectably bringing said first and second prongs together and pushing them apart,
• wherein said first prong further includes, at said distal end, a staple receptor, with a channel, for mounting said staple thereon, said channel defining an x-axis of the x;y;z coordinate system, parallel to said staple length span, and perpendicular to the direction of bringing first and second prongs together and pushing them apart,
• wherein said second prong further includes, at said distal end, a thin, cam-like head, having a width span that increases in the direction of increasing y, operable to increase said staple length span,
• and wherein, as said first and second prongs are brought together, said thin, cam-like head is arranged to slide between said staple receptor and said staple, mounted thereon, so as to wedge between said staple receptor and said staple and increase the length span of said staple.