Disclosed is a prosthetic device for distracting spinal column segments in the lumbar and the lumbar-sacral regions comprising a first engagement arm, a second engagement arm, a coupling mechanism and a locking mechanism. The first and the second engagement arms are configured to receive a lamina portion of the spinal column segment. The coupling mechanism is disposed between the first and the second engagement arms and is configured to allow the device to transition from an unextended configuration to an extended configuration in order to distract the spinal column segment. The locking mechanism is configured to maintain the extended configuration of the device.