Anti-splay head and set screw for spinal fixation

An anti-splaying system comprising:

• a bone anchor;
• a spinal rod;
• a receiver being configured for connection with the bone anchor, the receiver having a base, a first arm, a second arm, a first locking channel, and a second locking channel, the first arm and the second arm each extending from the base defining a rod-receiving cavity between the arms, the first and second arms including first and second inner threads formed in respective inner surfaces of the first and second arms, the first locking channel being formed in the inner surface of the first arm and extending from a proximal opening to a proximal bottom at or adjacent a first proximal beginning of the first inner thread, and the second locking channel being formed in the inner surface of the second arm and extending from a proximal opening to a proximal bottom at or adjacent a second proximal beginning of the second inner thread;
• and
• a set screw for securing a rod in place in the receiver in a portion of the system, the set screw having a driving portion, a body portion, external threads extending from the body portion, and an intermediate locking component connected rotatably to the body portion;
• wherein the intermediate locking component of the set screw and the locking channels of the receiver are configured such that the locking component can, in operation of the system, be moved into a securing position in the locking channels and, when in the secured position, fixes the two arms from splaying away from each other.

A method for making an anti-splaying system comprising:

• forming a receiver configured for connection with a bone anchor, the receiver having a base, a first arm, a second arm, a first locking channel, and a second locking channel, the first arm and the second arm each extending from the base defining a rod-receiving cavity between the arms, the first and second arms including first and second inner threads formed in respective inner surfaces of the first and second arms, the first locking channel being formed in the inner surface of the first arm and extending from a proximal opening to a proximal bottom at or adjacent a first proximal beginning of the first inner thread, and the second locking channel being formed in the inner surface of the second arm and extending from a proximal opening to a proximal bottom at or adjacent a second proximal beginning of the second inner thread;
• and
• presenting a set screw for securing a rod in place in the receiver in portion of the system, the set screw having a driving portion, a body portion, external threads extending from the body portion, and an intermediate locking component connected rotatably to the body portion and having opposing locking ends,
• wherein the intermediate locking component of the set screw and the locking channels of the receiver are configured such that the locking component can, in operation of the system, be moved into a securing position in the locking channels and, when in the secured position, fixes the two arms from splaying away from each other.