Spinous process fixation system and methods thereof

A surgical method comprising:

• inserting an implantable device into an interspinous space, wherein the implantable device is in a collapsed form having a first height;
• and
• expanding the implantable device in the interspinous space, wherein the implantable device is expanded to an expanded form having a second height,
• wherein the implantable device comprises:
• an upper assembly including a pair of upwardly facing extensions;
• a lower assembly including a pair of downwardly facing extensions;
• an actuation assembly positioned between the upper assembly and the lower assembly for changing a distance of separation between the upper assembly and the lower assembly, wherein the actuation assembly comprises a first ramped actuator, a second ramped actuator and a central screw, wherein rotation of the central screw draws the first ramped actuator toward the second ramped actuator, thereby causing expansion of the implantable device;
• a first spike plate assembly inserted through at least one of the upwardly facing extensions;
• and
• a second spike plate assembly inserted through at least one of the downwardly facing extensions.