Method and apparatus utilizing interference fit screw shanks for nonmetallic spinal stabilization

A nonmetallic stabilizing plate system, for the purpose of fixing one bone segment with respect to one or more other bone segments within a bone column, said system comprising:

• (a) a nonmetallic plate member having a posterior side for fixation to individual bone segments, selectively providing a plurality of attachment holes to said plate with desired angles for receiving nonmetallic bone screws to achieve a desired plate-screw relationship;
• (b) a plurality of nonmetallic bone screws configured to engage said nonmetallic plate, and to engage the bone segments, for the purpose of retaining said plate to said bone segments;
• and
• (c) said bone screws having a threaded portion, an interference fit portion and a head portion, the interference fit portion having at least one plate contacting surface, and the plate having at least one screw contacting surface, wherein the an interference fit portion is configured and sized such that when the screw is tightened, the at least one plate contacting surface is affixed to the plate by an interference fit, wherein the interference fit decreases bending stresses in the bone screws.

A nonmetallic stabilizing plate system, for the purpose of fixing one bone segment with respect to one or more other bone segments within a bone column, said system comprising:

• (a) a nonmetallic plate member having a posterior side for fixation to individual bone segments, said plate having a plurality of attachment holes for receiving nonmetallic bone screws, wherein the nonmetallic plate member is made of a first material;
• (b) a plurality of nonmetallic bone screws configured to engage said nonmetallic plate, and to engage the bone segments, for the purpose of retaining said plate to said bone segments, wherein the nonmetallic bone screws are made of a second material;
• and
• (c) said bone screws having a threaded portion, an interference fit portion and a head portion, the interference fit portion having at least one plate contacting surface, and the plate having at least one screw contacting surface, wherein the interference fit portion is configured and sized such that when the screw is tightened, the at least one plate contacting surface is affixed to the plate by an interference fit, wherein the first and second materials from which the plate and the screws are made are matched to one another such that the interference fit places the screw contacting surface in compression and substantially decreases bending stresses in the bone screws.