Expandable intervertebral cage and surgical method

A bio-compatible intervertebral prosthesis for implantation between adjacent vertebrae comprising:

• a) a cylindrically shaped cage body that includes at least first and second separable sections configured and sized to be inserted between adjacent vertebrae, each section having a flat inner surface portion that engages the flat inner surface of the other component;
• b) said separable sections being separable along the longitudinal axis of said cage body;
• c) the cage body having an anterior fitting integral thereto with an internally threaded bore;
• d) the cage body having anterior and posterior end portions;
• e) each of the cage body sections having a conically shaped internal recess with a bearing surface;
• f) an externally threaded expansion screw that engages the internal threads of the fitting, the screw having proximal and distal end portions, the proximal end having a tool receptive socket thereon for forming a connection with a rotary driver tool that can rotate the screw, the distal end portion being sized and shaped to force the first and second components apart as the screw advances longitudinally within the cage body to engage the recess surface along the length of the distal end of said expansion screw and in a direction from the anterior to the posterior end portions thereof;
• g) wherein said expansion screw has a length less than the length of the cage body and wherein said expansion screw does not extend beyond the end of said cage body;
• and
• h) wherein the first and second sections move apart incrementally as the screw advances into the internally threaded bore and recess surface.

A bio-compatible intervertebral prothesis for implantation between adjacent vertebrae comprising:

• a) a cylindrically shaped cage body that includes at least first and second separable cage sections configured and sized to be inserted between adjacent vertebrae, each having
• b) a flat inner surface portion that engages the flat inner surface of the other component;
• c) said separable sections being separable along the longitudinal axis of said cage body;
• d) the cage body having an anterior fitting integral thereto with an internal bore;
• e) the cage body having anterior and posterior end portions;
• f) each of the cage body sections having a conically shaped internal recess surface with a bearing surface;
• g) An expansion pin that engages the bore of the anterior fitting, the pin having proximal and distal end portions, the proximal end having a tool receptive portion thereon for forming a connection with a driver tool that can manipulate the pin, the distal end portion being sized and shaped to force the first and second sections apart as the pin advances longitudinally within the cage body to engage the recess surface along the length of the distal end of said expansion screw in a direction from the anterior to the posterior end portions thereof;
• h) wherein said expansion screw has a length less than the length of the cage body and wherein said expansion screw does not extend beyond the end of said cage body;
• and
• i) wherein the first and second sections move apart incrementally as the pin advances into the bore and recess surface.

A method for providing bio-compatible vertebral interbody fusion in the vertebral column comprising the steps of:

• a) preparing a space for receiving an orthopedic prosthetic device between two vertebrae;
• b) surgically inserting a substantially cylindrically shaped spinal cage body into the space between the vertebrae, wherein the spinal cage includes upper and lower cage sections;
• each of the cage body sections having an internal recess with a bearing surface;
• and
• c) advancing a unitary screw member to separate incrementally the upper and lower cage sections;
• wherein said screw member has a length less than the length of the cage body and does not extend beyond the end of said cage body and wherein the screw member includes a distal end portion being sized and shaped to engage the recess surface of the first and second cage sections and to force the first and second cage sections apart as the screw advances longitudinally into the cage body.