Multi-axial expandable pedicle screw and an expansion method thereof

An method of expanding a multi-axial expandable pedicle screw device, comprising:

• connecting a pedicle screw with other medical parts;
• transmitting a pressing force to an inner needle positioned in a bore of a hollow screw, the hollow screw having a tip at an end and an adapter-mating end at another end, the bore including an opening at the adapter-mating end of the hollow screw and a tapered tip at an intermediate location between the adapter-mating end and the tip of the hollow screw, wherein
• an adapting piece is connected to the adapter-mating end of the hollow screw, and a fixation rod is received in a cavity of the adapting piece and positioned above the inner needle in the bore,
• the step of transmitting a pressing force to the inner needle includes transmitting a pressing force from the fixation rod, through a fixation-rod-press technique, to drive the inner needle into the bore of the hollow screw and thereby controllably expand the hollow screw.

A multi-axial expandable pedicle screw device, comprising:

• a hollow screw having a tip at an end and an adapter-mating end at another end, with a bore formed inside, the bore including an opening at the adapter-mating end of the hollow screw and a tapered tip at an intermediate location between the adapter-mating end and the tip of the hollow screw, the bore being adapted to receive an inner needle therein;
• expansion gaps uniformly arranged on, and extending axially along the hollow screw, from the tip of the bore to the tip of the hollow screw;
• the adapter-mating end of the hollow screw being connected with an adapting piece, in the form of a universal joint having a cavity with an open pore, the adapter-mating end being adapted such that, when an inner needle is received in the bore and the adapter-mating end is connected with an adapting piece having a fixation rod mounted in the cavity, the mounted fixation rod will be positioned above the received inner needle in a manner to enable transmittance of a pressing force to the received inner needle, wherein
• the hollow screw is adapted to receive an inner needle that has a length which is greater than the length of the bore,
• the bore is adapted to receive an inner needle in a non-threaded reception, and
• the screw device is configured such that, when an inner needle is received in the bore and an adapting piece is connected to the hollow screw, with a fixation rod received in a cavity of the adapting piece, transmitting a pressing force to the received inner needle, from the fixation rod, will drive the inner needle into the bore to cause an expansion of the hollow screw.