Minimally invasive expanding spacer and method

A device to space vertebral members comprising:

• a first plate and a second plate;
• a first linkage pair pivotally attached to the first plate and the second plate;
• a second linkage pair pivotally attached to the first plate and the second plate, the second linkage pair being longer than the first linkage pair;
• a first toothed end of the first linkage pair attached to the first plate mates with a first toothed end of the second linkage pair, and a second toothed end of the first linkage pair attached to the second plate mates with a second toothed end of the second linkage pair when a distance between the first plate and the second plate increases and an angle formed between the first plate and the second plate changes.

A device to space vertebral members comprising:

• a first plate;
• a second plate;
• a pull arm positioned between the first plate and the second plate;
• a first linkage pair and a second linkage pair each comprising a first end connected to the first plate, a second end connected to the second plate, the first linkage pair connected to the pull arm at a first connection point, and the second linkage pair connected to the pull arm at a second connection point, the first linkage pair having a different length than the second linkage pair;
• the device positionable between a first orientation having a first height and a second orientation having a second height greater than the first height, a distance between the first connection point and the second connection point being greater in the first orientation than in the second orientation and an angle formed between the plates being different in the first orientation and the second orientation.