Compression osteosynthesis screw, and an ancillaty device for use therewith
First Claim
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1. An osteosynthesis screw for applying compression to bone fragments, the screw comprising:
- a screw shank having a thread with a distal zone and a proximal zone, and a screw head for threading on said screw shank and for co-operating with said proximal zone via internal tapping complementary to the thread of said shank, said screw head having an outside thread at a pitch that is smaller than the pitch of the thread of said screw shank, wherein said distal zone and said proximal zone are separated by a central zone, shaped to be inactive during screwing, to form a sliding zone for putting bone fragments into compression.
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Abstract
An osteosynthesis screw comprising both a screw shank, having a thread with a distal zone and a proximal zone, and a screw head for threading on the screw shank and for co-operating with its proximal zone via internal tapping complementary to the thread of the shank is suitable for applying compression to bone fragments. The screw head also has an outside thread at a pitch that is smaller than the pitch of the screw shank, wherein the distal zone and the proximal zone are separated by a central zone shaped to be inactive during screwing so as to form a sliding zone for the bone fragments to be put into compression.
263 Citations
18 Claims
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1. An osteosynthesis screw for applying compression to bone fragments, the screw comprising:
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a screw shank having a thread with a distal zone and a proximal zone, and a screw head for threading on said screw shank and for co-operating with said proximal zone via internal tapping complementary to the thread of said shank, said screw head having an outside thread at a pitch that is smaller than the pitch of the thread of said screw shank, wherein said distal zone and said proximal zone are separated by a central zone, shaped to be inactive during screwing, to form a sliding zone for putting bone fragments into compression. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
a first screwdriver designed for screwing the screw shank and a second screwdriver designed for turning the screw head, said first screwdriver being engaged axially inside the second screwdriver to enable the screw shank and the screw head to be turned simultaneously, and said first screw driver being separable therefrom to enable the screw head to be turned individually, said second screwdriver provided at its working end portion with an internal setback designed to receive a collar of the screw shank in an abutment position against an end of the setback, said setback being of a depth such that when the collar comes into abutment against its end while the screw head is being turned, further turning thereof is automatically blocked before a last turn of the proximal thread has been reached to prevent the screw head from escaping from said proximal thread.
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17. An ancillary device according to claim 16, wherein the depth of the setback is such that turning of the screw head is interrupted automatically while all of the tapping is engaged on the proximal thread.
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18. In a method of uniting bone fragments comprising bringing bone fragments together and putting said bone fragments under compression using an osteosynthesis screw, the improvement wherein said osteosynthesis screw comprises the osteosynthesis screw of claim 1.
Specification