Abstract: A compression fastener may include a shaft and a helical thread disposed about the shaft. The shaft may include a proximal end, a distal end, a proximal shaft portion, and a distal shaft portion. The helical thread may include at least one concave undercut surface and a plurality of pitches that may include at least one first pitch along the proximal shaft portion and at least one second pitch along the distal shaft portion. The at least one concave undercut surface may be angled towards one of the proximal end and the distal end of the shaft, and the at least one first pitch and the at least one second pitch may not be equal to each other.

Abstract: A femoral fixation device may include a shaft and a helical thread disposed about the shaft between a first location and a second location along the shaft. The helical thread may include a concave undercut surface. The femoral fixation device may be configured such that, when the femoral fixation device is implanted within a neck and a head of a femoral bone: the first location, the second location, and the helical thread therebetween may be disposed within the head of the femoral bone; the concave undercut surface may be oriented toward a proximal end of the femoral fixation device; and the concave undercut surface may be configured to transmit at least one force from the head of the femoral bone to the neck of the femoral bone.

Abstract: A process of forming a fastener with improved threading to resist multi-axial forces and off-axis loading scenarios is provided. The process may include placing first and second mill tools adjacent a shaft of the fastener having a proximal end and a distal end, rotating the shaft and the first and second mill tools, and translating the first and second mill tools along at least part of a length of the shaft to form: a first concave undercut surface oriented toward the proximal end, a first convex undercut surface oriented toward the distal end, a second concave undercut surface oriented toward the distal end, and a second convex undercut surface oriented toward the proximal end.

Abstract: A fastener with improved threading for resisting multi-axial forces and off-axis loading scenarios is provided. The fastener may include a shaft and a plurality of helical threads disposed about the shaft. The plurality of helical threads may include a first helical thread and a second helical thread adjacent the first helical thread. The first helical thread may include a first concave undercut surface and a first convex undercut surface. The second helical thread may include a second concave undercut surface and a second convex undercut surface. When the fastener is viewed in section along a plane intersecting a longitudinal axis of the shaft, the first concave undercut surface and the second convex undercut surface may be oriented toward the proximal end of the shaft, and the first convex undercut surface and the second concave undercut surface may be oriented toward the distal end of the shaft.

Abstract: A pedicle bone fastener may include a shaft, a helical thread, and an integrated attachment feature. The shaft may include a proximal end, a distal end, and a longitudinal axis. The helical thread may be disposed about the shaft along the longitudinal axis between the proximal and distal ends of the shaft. The helical thread may include a first undercut surface and a second undercut surface. The first undercut surface may be angled toward one of the proximal end and the distal end of the shaft and the second undercut surface may be angled toward the other one of the proximal end and the distal end of the shaft. The integrated attachment feature may be disposed at the proximal end of the shaft and configured to be adjustably secured to a spinal stabilization implement.

Abstract: A femoral fixation device may include a shaft and a helical thread disposed about the shaft between a first location and a second location along the shaft. The helical thread may include a concave undercut surface. The femoral fixation device may be configured such that, when the femoral fixation device is implanted within a neck and a head of a femoral bone: the first location, the second location, and the helical thread therebetween may be disposed within the head of the femoral bone; the concave undercut surface may be oriented toward a proximal end of the femoral fixation device; and the concave undercut surface may be configured to transmit at least one force from the head of the femoral bone to the neck of the femoral bone.

Abstract: A method of preventing bone blowout may include forming a hole in a bone, the hole having a bone hole diameter, and inserting a bone fastener into the hole. The bone fastener may include a shaft having a minor diameter and a helical thread. The helical thread may be disposed about the shaft and may include a first undercut surface and a second undercut surface. The first undercut surface may be angled toward one of the proximal end and the distal end of the shaft, and the second undercut surface may be angled toward the other one of the proximal end and the distal end of the shaft. The minor diameter of the shaft may not be greater than 5% larger the bone hole diameter.

Abstract: A pedicle bone fastener may include a shaft, a helical thread, and an integrated attachment feature. The shaft may include a proximal end, a distal end, and a longitudinal axis. The helical thread may be disposed about the shaft along the longitudinal axis between the proximal and distal ends of the shaft. The helical thread may include a first undercut surface and a second undercut surface. The first undercut surface may be angled toward one of the proximal end and the distal end of the shaft and the second undercut surface may be angled toward the other one of the proximal end and the distal end of the shaft. The integrated attachment feature may be disposed at the proximal end of the shaft and configured to be adjustably secured to a spinal stabilization implement.

Abstract: A process of forming a fastener with improved threading to resist multi-axial forces and off-axis loading scenarios is provided. The process may include placing first and second mill tools adjacent a shaft of the fastener having a proximal end and a distal end, rotating the shaft and the first and second mill tools, and translating the first and second mill tools along at least part of a length of the shaft to form: a first concave undercut surface oriented toward the proximal end, a first convex undercut surface oriented toward the distal end, a second concave undercut surface oriented toward the distal end, and a second convex undercut surface oriented toward the proximal end.

Abstract: A fastener with improved threading for resisting multi-axial forces and off-axis loading scenarios is provided. The fastener may include a shaft and a plurality of helical threads disposed about the shaft. The plurality of helical threads may include a first helical thread and a second helical thread adjacent the first helical thread. The first helical thread may include a first concave undercut surface and a first convex undercut surface. The second helical thread may include a second concave undercut surface and a second convex undercut surface. When the fastener is viewed in section along a plane intersecting a longitudinal axis of the shaft, the first concave undercut surface and the second convex undercut surface may be oriented toward the proximal end of the shaft, and the first convex undercut surface and the second concave undercut surface may be oriented toward the distal end of the shaft.

Abstract: A dual-start fastener is disclosed having two threads helically wound about its shaft. The thread tooth profile (in section) constitutes substantially parallel upper and lower facets on each thread flank. A first thread has a crest diameter greater than a second thread. A distal end of the fastener includes self-tapping cutters formed on the threads which force shards of bone to advance into shallow troughs adjacent the cutters for subsequent resorption by adjacent osseous tissue.

Abstract: A fastener for embedment in bone includes a chevron-shaped thread pattern having a first radial superior surface at an angle beta on a blank relative to a longitudinally extending axis of the fastener, a second radial superior surface at an angle alpha inboard to the first radial superior surface and relative to the longitudinally extending axis such that the two superior surfaces form a V-shape geometry. The fastener further includes a flank surface underlying the second radial superior surface at an angle gamma, the angle gamma defining an angle with the longitudinally extending axis that is 90°, a relief surface underlying the first radial superior surface such that the flank surface and the relief surface form a V-shape geometry, and a radially-outermost surface adjacent to the relief surface and defining a major diameter of the thread pattern, the radially-outermost surface being parallel to the longitudinally extending axis of the fastener.

Abstract: A threaded fastener for embedment into bone is disclosed. Threads are formed on cylindrical stock. The thread pattern features upper and lower surfaces. The upper surface includes (in section) two facets which intersect to form a “V” shaped contour and a lower surface which is undercut below an upper facet nearest a root of the fastener thread. The fastener includes a self-tapping cutter at a distal extremity and a driving head at its proximal extremity. The cylindrical stock contemplates two variants: it may be hollow from the proximal end to the self-tapping cutter or from the self-tapping cutter to its distal end. The self-tapping cutter is configured to feed bone shards into the hollow.