A bone fixation system comprising: a bone implant elongate along a longitudinal direction, the bone implant including an implant body that defines an upper surface, a bone-facing surface spaced from the upper surface along a transverse direction that is perpendicular to the longitudinal direction, at least one aperture that extends through the implant body from the upper surface to the bone-facing surface, the at least one aperture defined by an inner wall, wherein the inner wall is defined by a first and a second wire segment (102, 104), and a portion of the inner wall is curved along the transverse direction to define a convexly shaped outer surface, and wherein the inner wall comprises a first threaded region (40, 42) on the convexly shaped outer surface; and at least one bone fixation element configured to be inserted at least partially through the at least one aperture into an underlying bone, the bone fixation element defining a proximal end and a distal end spaced from the proximal end along a central axis in a distal direction, the bone fixation element defining a head disposed at the proximal end and a shaft that extends relative to the head towards the distal end, the head defining a first ridge and a second ridge that is spaced from the first ridge along the distal direction, and a groove disposed between the first and second ridges (56, 58), the groove being unthreaded and recessed into the head toward the central axis between the first and second ridges (56, 58), wherein the groove is configured to receive at least a portion of the inner wall such that the first and second ridges (56, 58) couple the bone fixation element to the bone implant; wherein the first ridge is convex with respect to the central axis and has a first ridge apex; wherein the second ridge is convex with respect to the central axis and has a second ridge outer surface comprising a second threaded region that is configured to threadingly engage the first threaded region (40, 42); wherein the bone fixation element is configured such that the bone fixation element can be inserted through the at least one aperture with the second threaded region disengaged from, and spaced in the distal direction from, the first threaded region (40, 42), and the first threaded region (40, 42) being positioned adjacent the groove and spaced in the distal direction from the first ridge apex. a bone implant elongate along a longitudinal direction, the bone implant including an implant body that defines an upper surface, a bone-facing surface spaced from the upper surface along a transverse direction that is perpendicular to the longitudinal direction, at least one aperture that extends through the implant body from the upper surface to the bone-facing surface, the at least one aperture defined by an inner wall, wherein the inner wall is defined by a first and a second wire segment (102, 104), and a portion of the inner wall is curved along the transverse direction to define a convexly shaped outer surface, and wherein the inner wall comprises a first threaded region (40, 42) on the convexly shaped outer surface; and at least one bone fixation element configured to be inserted at least partially through the at least one aperture into an underlying bone, the bone fixation element defining a proximal end and a distal end spaced from the proximal end along a central axis in a distal direction, the bone fixation element defining a head disposed at the proximal end and a shaft that extends relative to the head towards the distal end, the head defining a first ridge and a second ridge that is spaced from the first ridge along the distal direction, and a groove disposed between the first and second ridges (56, 58), the groove being unthreaded and recessed into the head toward the central axis between the first and second ridges (56, 58), wherein the groove is configured to receive at least a portion of the inner wall such that the first and second ridges (56, 58) couple the bone fixation element to the bone implant; wherein the first ridge is convex with respect to the central axis and has a first ridge apex; wherein the second ridge is convex with respect to the central axis and has a second ridge outer surface comprising a second threaded region that is configured to threadingly engage the first threaded region (40, 42); wherein the bone fixation element is configured such that the bone fixation element can be inserted through the at least one aperture with the second threaded region disengaged from, and spaced in the distal direction from, the first threaded region (40, 42), and the first threaded region (40, 42) being positioned adjacent the groove and spaced in the distal direction from the first ridge apex.