Abstract: A converter for use in a high speed rotationally oscillating surgical burring device comprises an output shaft, and a rotationally oscillating secondary drive rotor coupled to the output shaft. The secondary drive rotor is arranged and configured with a size and mass to minimize its angular momentum. A unidirectionally rotating primary drive rotor is provided. A linearly reciprocating transmission converts unidirectional rotation to bidirectional rotational oscillation coupling the primary and secondary drive rotors. The transmission is arranged and configured with a size and mass to minimize its linear momentum. An input shaft is coupled to the rotating primary drive rotor to which a unidirectional rotational force is applied.

Abstract: A converter for use in a high speed rotationally oscillating surgical burring device comprises an output shaft, and a rotationally oscillating secondary drive rotor coupled to the output shaft. The secondary drive rotor is arranged and configured with a size and mass to minimize its angular momentum. A unidirectionally rotating primary drive rotor is provided. A linearly reciprocating transmission converts unidirectional rotation to bidirectional rotational oscillation coupling the primary and secondary drive rotors. The transmission is arranged and configured with a size and mass to minimize its linear momentum. An input shaft is coupled to the rotating primary drive rotor to which a unidirectional rotational force is applied.

Abstract: A spinal fusion cage comprises an upper half-cage, a lower half-cage, and a plunger with a cam. The upper half-cage and lower half-cage have a first collapsed configuration which has a thin, flat, rectangular envelope and a second expanded configuration. The half-cages have at least one ramped surface on which the cam of the plunger rides. The cam bears against the ramped surface and spreading the two half-cages apart. A method of deploying a spinal fusion cage comprises the steps of disposing in a spinal space an upper half-cage and lower half-cage in a first collapsed configuration which has a thin, flat, rectangular envelope and a second expanded configuration. The method continues with the step of distally advancing a plunger between the upper half-cage and lower half-cage and spreading the two half-cages apart.

Abstract: Correction of a scoliotic curve in a spine comprises the steps of implanting an expanding rod isolated completely under the skin and attached to selected portions of the scoliotic curve of the spine at opposing ends of the rod; and producing a controlled force by means of expansion of the rod over at an extended time period under external control until a desire spinal curve is obtained. An incremental force is generated to stretch the scoliotic curve of the spine between the selected portions where attachment of the rod is defined. The controlled force is provided steadily for at least one month or alternatively 1-3 months. Multiple rods may be employed each associated with a different scoliotic curve of the spine or a different portion of the scoliotic curve.