Bone screw
AssigneeBiedermann Motech GmbH
InventorsLutz Biedermann, Jurgen Harms
Life of this patent
Estimating the term…
Abstract
A bone screw comprises a receiver member (5) and a screw member (1) having a threaded portion (2) and a head (3) having a spherical segment-shaped portion. The receiver member (5) comprises an internal thread (10) for allowing a relative adjustment of receiver member and screw member and the connection of the receiver member with a round rod. A pressure means (12) acts onto the head (3) and the rod (16) is placed on top of the pressure means. The arrangement is locked by means of a rod locking nut (13) and a lock nut (14) is screwed onto an external thread (11).
Claims7
A bone screw for connecting a bone with a rod, said bone screw comprising
- a screw member having a threaded portion and a head, said head having a spherical segment-shaped portion,
- a cylindrical receiver member for receiving said head of said screw member and said rod, said receiver member having a first end and a second end, a bore provided in said receiver member between said first and second ends, a hollow spherical portion in said bore for receiving said head at a position inwards of said second end, said cylindrical receiver member further having a substantially U-shaped cross-section with two free legs which are provided with an external thread, and an internal thread,
- a pressure means having a portion acting on said head, and
- a locking screw screwed onto said receiver member internal thread at said first end thereof for locking said rod in place when inserted into said U-shaped member cross-section and;
- a lock nut screwed onto said external thread.
A bone screw assembly for connecting a bone with a rod comprising
- a screw member having a head and a threaded portion, said head has a spherical segment shaped portion, a cylindrical receiver member with a substantially U-shaped cross-section with two free legs and having an axial bore with an internal threaded portion and a narrow portion means for maintaining the screw head in said bore while said screw threaded portion extends outside said bore,
- a first locking nut positioned on the internal threaded portion of the bore for engaging the head of said screw to hold it in place, and
- a second locking nut on said internal threaded portion of the bore for holding a rod positioned between said legs in place.
Dependencies are inferred from the claim text.