Abstract: A surgical implant is provided that includes first and second abutment surfaces between which are positioned a force imparting mechanism. A sheath is positioned between the first and second abutment surfaces, and surrounds the force imparting mechanism. The sheath is fabricated from a material that accommodates relative movement of the abutment members, while exhibiting substantially inert behavior relative to surrounding anatomical structures. The sheath is generally fabricated from expanded polytetrafluoroethylene, ultra-high molecular weight polyethylene, a copolymer of polycarbonate and a urethane, or a blend of a polycarbonate and a urethane. The force imparting member may include one or more springs, e.g., a pair of nested springs. The surgical implant may be a dynamic spine stabilizing member that is advantageously incorporated into a spine stabilization system to offer clinically efficacious results.

Abstract: A surgical implant is provided that includes first and second abutment surfaces between which are positioned a force imparting mechanism. A sheath is positioned between the first and second abutment surfaces, and surrounds the force imparting mechanism. The sheath is fabricated from a material that accommodates relative movement of the abutment members, while exhibiting substantially inert behavior relative to surrounding anatomical structures. The sheath is generally fabricated from expanded polytetrafluoroethylene, ultra-high molecular weight polyethylene, a copolymer of polycarbonate and a urethane, or a blend of a polycarbonate and a urethane. The force imparting member may include one or more springs, e.g., a pair of nested springs. The surgical implant may be a dynamic spine stabilizing member that is advantageously incorporated into a spine stabilization system to offer clinically efficacious results.

Abstract: A device includes a tubular element, and a cutter spring-biased relative to the tubular element. In an unloaded configuration the cutter is displaced relative to the tubular element by a displacement distance, and when the cutter is in a loaded configuration the displacement distance is reduced. A first structure is longitudinally fixed relative to the cutter and rotationally engaged relative to the tubular element. A length of the first structure extends proximally in the unloaded configuration. A second structure is longitudinally displaceable relative to the first structure. In the loaded configuration, a driver engages and rotates both the first and second structures, and thus the tubular element and cutter together. Once the cutter breaks through the bone, the cutter spring-biased into the unloaded configuration, resulting in disengagement of the first structure from the driver to prevent rotation of either the tubular element or the cutter.