Expandable implant with deflectable sequence of segments
An implant ( 100, 200, 300, 400 ) includes a base ( 10 ), and a sequence of at least two segments including a first segment ( 12 ) and a last segment ( 14 ). The first segment ( 12 ) is pivotally linked to base ( 10 ). Adjacent segments are interconnected at pivotal connections ( 18 ). A bolt ( 20 ) has a threaded shaft ( 22 ) and a head ( 24 ). The threaded shaft ( 22 ) is engaged in a threaded channel ( 26 ) of the base ( 10 ) so that rotation of the bolt ( 20 ) about a central axis of the threaded shaft ( 22 ) varies a degree of overlap between the base ( 10 ) and the bolt ( 20 ). The last segment ( 14 ) and the head ( 24 ) define therebetween a spherical bearing ( 28 ). Rotation of bolt ( 20 ) thus varies a distance between spherical bearing ( 28 ) and hinge pin ( 16 ), thereby causing deflection of the sequence of segments.
1. An implant comprising:
(a) a base;
(b) a sequence of at least two segments including a first segment and a last segment, said first segment being pivotally linked to said base, adjacent segments of said sequence of segments being interconnected at pivotal connections; and
(c) a bolt having a threaded shaft with a central axis and a head, said threaded shaft being engaged in a threaded channel of said base, wherein said last segment and said head define therebetween a spherical bearing such that rotation of said bolt about said central axis varies a degree of overlap between said base and said bolt, and causes deflection of said sequence of segments.
2. The implant of claim 1 , wherein said sequence comprises only two segments.
3. The implant of claim 2 , wherein a first of said two segments extends along a majority of a length of said sequence, and wherein a second of said two segments extends along less than half of the length of said sequence.
4. The implant of claim 3 , wherein said first segment and said second segment are interconnected at a pivot axis, wherein said pivot axis is located within a medial 50% of a length of said first segment.
5. The implant of claim 1 , wherein said sequence includes three segments.
6. The implant of claim 5 , wherein said three segments comprise a major intermediate segment and first and last linking segments.
7. The implant of claim 6 , further comprising a gear-tooth engagement to preserve parallel orientation of the intermediate segment to the base.