Implantable bone distraction device

An implantable device for distracting first and second bone segments, comprising:

• A. an elongated first plate extending along a first axis between first and second ends thereof, said first plate having an upper surface and a lower surface, and having means near said first end for affixing said first plate to said first bone segment whereby said lower surface of said first plate is adjacent to said first bone segment;
• B. an elongated second plate extending along a second axis between first and second ends thereof, said second plate having an upper surface and a lower surface, and having means near said first end for affixing said second plate to said second bone segment whereby said lower surface of said second plate is adjacent to said second bone segment;
• C. and means for positioning said first and second plates to be slidingly engaged, with at least the portion of said first plate including said second end being adjacent to at least the portion of said second plate including said first end, whereby said first and second axes are substantially parallel, and whereby said first plate is movable with respect to said second plate in the direction of said first and second axes;
• wherein said upper surface of said first plate includes a plurality of parallel saw-tooth ridges extending transverse to said first axis, each of said ridges including a drive surface, said drive surface extending from, and being substantially perpendicular to, said upper surface of said first plate and facing said second end of said first plate,
• wherein said second plate comprises at least one resilient pawl extending from said first end of said second plate, said pawl being biased toward and engaging with one of said ridges, and
• wherein said second plate further comprises at least one resilient elongated ratchet arm having a proximal end extending from said first end of said second plate and a distal end extending toward and engaging with one of said ridges.