Centering means for holes of intramedullary nails

Claim 1

Means for determining the centering alignment of blind holes of an installed intramedullary nail, especially for a bone-surgery operation on a fractured limb, comprising: (a) a nail (9) which can be inserted into a medullary cavity (M), which is provided with a distal end (10) and a proximal end (8) and a plurality of spaced transverse holes (11-16) for bone bolts in the proximity of the said ends; (b) a frame (2) for supporting the proximal end of the nail from outside the limb, said frame comprising an elongate template (3) having transverse passages (17-22) for drilling tools, and a transverse arm (4) for removable attachment of the nail to said frame; (c) means (7) for removably coupling the proximal end (8) of the nail (9) to the transverse arm (4) so that the nail (9) is substantially parallel to the template (3) with its holes (11-16) at the same distance from arm (4) as the corresponding passages (17-22) in the template (3); and (d) means (25) for aligning the passages in the template with the holes in the nail by movement of the distal end (24) of the template in a plane which is substantially perpendicular to axes of the passages and the holes, the means of alignment (25) comprising a stabilizing member (26) which can be anchored to the bone beyond the distal end (10) of the nail and which is coupled to the distal end (24) of the template through means of attachment of adjustable length, whereby to selectively position the distal end of the template in said plane and to secure a position of registration as between the distal ends of the template and of the nail.

Claim 12

The method of locating a template guide bore in registry with a blind transverse bolt hole in an intramedullary nail that has been implanted in the medular cavity of a fractured bone, which comprises the steps of: (a) mounting the template external to the bone and parallel to the intramedullary nail with the proximal end of the template connected to the proximal end of the nail, the axes of the template guide bore and of the transverse bolt hole being parallel and equidistant from said connection and the distal end of the template being movable in a plane perpendicular to said axes; (b) selecting a metal-detector having a directional axis of force-field response and mounting the same to the template to position the directional axis perpendicular to said plane and in non-invasive proximity to the bone; (c) moving said distal end in said plane and in a direction which traverses registry with the intramedullary nail, whereby to scan the force field from one to the other side of registry with the nail, whereby to sense a force-field anomaly upon scanned swept traverse of the nail; and (d) determining the center of symmetry of the force-field anomaly, thereby identifying the location of template guide-bore registry with the blind hole in the intramedullary nail.

Claim 13

The method of locating a template guide bore in registry with a blind transverse bolt hole in an intramedullary nail that has been implanted in the medular cavity of a fractured bone, which comprises the steps of: (a) mounting the template external to the bone and parallel to the intramedullary nail with the proximal end of the template connected to the proximal end of the nail, the axes of the template guide bore and of the transverse bolt hole being parallel and equidistant from said connection and the distal end of the template being movable in a plane perpendicular to said axes; (b) selecting a metal-detector having a directional axis of force-field response and mounting the same to the template to position the directional axis perpendicular to said plane and in non-invasive proximity to the bone; (c) moving said distal end in said plane and in a direction which traverses registry with the intramedullary nail, whereby to scan the force field from one to the other side of registry with the nail, whereby to sense a force-field anomaly upon scanned swept traverse of the nail; and (d) determining the center of symmetry of the force-field anomaly, thereby identifying the location of template guide-bore registry with the blind hole in the intramedullary nail.

Claim 16

The method of locating a template guide bore in registry with a blind transverse bolt hole in an intramedullary nail that has been implanted in the medular cavity of a fractured bone, which comprises the steps of: (a) mounting the template external to the bone and parallel to the intramedullary nail with the proximal end of the template connected to the proximal end of the nail, with the axes of the template guide bore and of the transverse bolt hole parallel and equidistant from said connection and the distal end of the template being movable in a plane perpendicular to said axes; (b) establishing a stabilizing reference to a part of the bone which is distal to the distal end of the nail; (c) selecting a metal-detector and mounting the same to establish a force field embracing that part of the nail which is characterized by the bolt hole; (d) moving said distal end in said plane and to one side of the distal end of the nail to a first location of predetermined metal-detector output; (e) measuring in said plane the distance of the distal end of the template from the stabilizing reference of step (b); (f) moving the distal end of the template in said plane and to the other side of the distal end of the nail and to a second location at which the same predetermined metal-detector output is noted; (g) measuring in said plane the distance of the distal end of the template from the stabilizing reference of step (b); (h) calculating from the measurements of steps (e) and (g) the half-way point of the sum of said measurements; and (i) clamping the distal end of the template to the stabilizing reference for a setting of the distal end of the template at the half-way point calculated by step (h).

Claim 17

The method of locating a template guide bore in registry with a blind transverse bolt hole in an intramedullary nail that has been implanted in the medular cavity of a fractured bone, which comprises the steps of: (a) mounting the template external to the bone and parallel to the intramedullary nail with the proximal end of the template connected to the proximal end of the nail, with the axes of the template guide bore and of the transverse bolt hole parallel and equidistant from said connection and the distal end of the template being movable in a plane perpendicular to said axes; (b) establishing a stabilizing reference to a part of the bone which is distal to the distal end of the nail; (c) selecting a metal-detector and mounting the same to establish a force field embracing that part of the nail which is characterized by the bolt hole; (d) moving said distal end in said plane and to one side of the distal end of the nail to a first location of predetermined metal-detector output; (e) measuring in said plane the distance of the distal end of the template from the stabilizing reference of step (b); (f) moving the distal end of the template in said plane and to the other side of the distal end of the nail and to a second location at which the same predetermined metal-detector output is noted; (g) measuring in said plane the distance of the distal end of the template from the stabilizing reference of step (b); (h) calculating from the measurements of steps (e) and (g) the half-way point of the sum of said measurements; and (i) clamping the distal end of the template to the stabilizing reference for a setting of the distal end of the template at the half-way point calculated by step (h).