An intervertebral implant comprising: a body (100, 200, 300, 700) with a plurality of openings (131, 134, 135, 136, 137, 231, 234, 235, 236, 237, 331, 334, 335, 336, 337, 731, 734, 735, 736, 737) therein, each of the plurality of openings being accessible from a single side of the body (100, 200, 300, 700); a fastener (121, 124, 127) disposed in a first opening of the plurality of openings; and a locking element (150A, 150B, 250A, 250B, 350A, 350B, 750A, 750B) disposed in a second opening of the plurality of openings comprising a head, a base abutting the head and a shaft extending from the base, wherein the locking element (150A, 150B, 250A, 250B, 350A, 350B, 750A, 750B) is movable between a first position relative to the body (100, 200, 300, 700) that blocks the first opening and a second position relative to the body (100, 200, 300, 700) that does not block the first opening, the locking element (150A, 150B, 250A, 250B, 350A, 350B, 750A, 750B) characterized in that: the base is a flexible base; and the shaft is a flexible shaft, wherein the flexible base and the flexible shaft extend along a longitudinal axis, and wherein the flexible base is movable from a first position to a second position such that in the first position and in the second position, the flexible base is secured to the body (100, 200, 300, 700) and has a first perimeter and in between the first position and the second position, a portion of the flexible base is deformed causing a cross-sectional size of the locking element (150A, 150B, 250A, 250B, 350A, 350B, 750A, 750B) to decrease in that the flexible base has a second perimeter smaller than the first perimeter, the first perimeter and the second perimeter being measured at the same axial location on the flexible base. a body (100, 200, 300, 700) with a plurality of openings (131, 134, 135, 136, 137, 231, 234, 235, 236, 237, 331, 334, 335, 336, 337, 731, 734, 735, 736, 737) therein, each of the plurality of openings being accessible from a single side of the body (100, 200, 300, 700); a fastener (121, 124, 127) disposed in a first opening of the plurality of openings; and a locking element (150A, 150B, 250A, 250B, 350A, 350B, 750A, 750B) disposed in a second opening of the plurality of openings comprising a head, a base abutting the head and a shaft extending from the base, wherein the locking element (150A, 150B, 250A, 250B, 350A, 350B, 750A, 750B) is movable between a first position relative to the body (100, 200, 300, 700) that blocks the first opening and a second position relative to the body (100, 200, 300, 700) that does not block the first opening, the locking element (150A, 150B, 250A, 250B, 350A, 350B, 750A, 750B) characterized in that: the base is a flexible base; and the shaft is a flexible shaft, wherein the flexible base and the flexible shaft extend along a longitudinal axis, and wherein the flexible base is movable from a first position to a second position such that in the first position and in the second position, the flexible base is secured to the body (100, 200, 300, 700) and has a first perimeter and in between the first position and the second position, a portion of the flexible base is deformed causing a cross-sectional size of the locking element (150A, 150B, 250A, 250B, 350A, 350B, 750A, 750B) to decrease in that the flexible base has a second perimeter smaller than the first perimeter, the first perimeter and the second perimeter being measured at the same axial location on the flexible base. wherein the locking element (150A, 150B, 250A, 250B, 350A, 350B, 750A, 750B) is movable between a first position relative to the body (100, 200, 300, 700) that blocks the first opening and a second position relative to the body (100, 200, 300, 700) that does not block the first opening, the locking element (150A, 150B, 250A, 250B, 350A, 350B, 750A, 750B) characterized in that: the base is a flexible base; and the shaft is a flexible shaft, wherein the flexible base and the flexible shaft extend along a longitudinal axis, and wherein the flexible base is movable from a first position to a second position such that in the first position and in the second position, the flexible base is secured to the body (100, 200, 300, 700) and has a first perimeter and in between the first position and the second position, a portion of the flexible base is deformed causing a cross-sectional size of the locking element (150A, 150B, 250A, 250B, 350A, 350B, 750A, 750B) to decrease in that the flexible base has a second perimeter smaller than the first perimeter, the first perimeter and the second perimeter being measured at the same axial location on the flexible base. the base is a flexible base; and the shaft is a flexible shaft, wherein the flexible base and the flexible shaft extend along a longitudinal axis, and wherein the flexible base is movable from a first position to a second position such that in the first position and in the second position, the flexible base is secured to the body (100, 200, 300, 700) and has a first perimeter and in between the first position and the second position, a portion of the flexible base is deformed causing a cross-sectional size of the locking element (150A, 150B, 250A, 250B, 350A, 350B, 750A, 750B) to decrease in that the flexible base has a second perimeter smaller than the first perimeter, the first perimeter and the second perimeter being measured at the same axial location on the flexible base.