Patent ID: 7549993

Claim:
A cam spreader comprising: an elongated portion comprising a handle and a longitudinal axis extending along its length; a cam portion extending from the elongated portion, the cam portion comprising: a substantially flat first lateral surface and an opposing substantially flat second lateral surface, the lateral surfaces extending substantially parallel to one another and separated by a first width, the lateral surfaces configured to engage a pair of adjacent vertebrae in a first position providing a first amount of lift to the vertebrae; a substantially flat upper surface and an opposing substantially flat lower surface, the upper and lower surfaces extending substantially parallel to one another and substantially perpendicular to the lateral surfaces, the upper and lower surfaces separated by a first height defining a second amount of lift, the first height being greater than the first width, the upper and lower surfaces configured to engage the pair of adjacent vertebrae in a second position providing a second amount of lift greater than the first amount lift; a first arcuate surface extending between the upper surface and the first lateral surface; a second arcuate surface extending between the first lateral surface and the lower surface; a third arcuate surface extending between the lower surface and the second lateral surface; and a fourth arcuate surface extending between the second lateral surface and the upper surface; wherein the first arcuate surface and the second arcuate surface are not defined by a single continuous arc and wherein the third arcuate surface and the fourth arcuate surface are not defined by a single continuous arc; wherein the first, second, third, and fourth arcuate surfaces are configured such that as the cam portion is rotated about the longitudinal axis between the first position and the second position the increase in lift between the first amount of lift and the second amount of lift is directly proportional to the degree of rotation.