Expandable worm screw jack for installation between upper and lower succeeding articular processes and having enhanced bone gripping geometry and teeth profiles

A spinal jack adapted for installation between first and second vertebral processes, comprising:

• an upper body portion and a lower body portion;
• each of said upper and lower body portions further including bone gripping surfaces adapted for engaging the vertebral processes, said bone gripping surfaces each further including a “U” shaped pocket, aligning apertures formed through spaced extending tabs defining each of said “U” shaped pockets;
• each of said “U” shaped pockets of said upper and lower body portions having a shape and configuration which permits reversible installation in either of one-hundred and eighty degree rotated positions for securing to the vertebral processes;
• rivets inserted between the aligning apertures and adapted to being pressed through a bone of the vertebral processes for securing said upper and lower body portions to the vertebral processes;
• and
• a worm gear mechanism for adjusting a separation distance between said vertebral processes via said upper and lower body portions and including a rotatable worm incorporated into said body for engaging a pair of outer worm gears communicating said worm with a pair of stems extending between communicating interiors of said upper and lower body portions for displacing said upper body portion relative to said lower body portion.