An interspinous process spacing device, comprising: - a first attachment side; - a second attachment side; - a spacer extending from the first attachment side and slideably insertable through a spacer slot formed in the second attachment side, wherein the spacer has an elongated shape defining a longitudinal axis of the spacer and is adapted to be positioned between a spinous process of a first vertebra and a spinous process of an adjacent second vertebra, and wherein the spacer comprises: -- a proximate end adjacent the first attachment side; -- a distal end opposite the proximate end in a direction of the longitudinal axis of the spacer; and -- a trough formed in a posterior surface of the spacer, wherein the trough has an elongated shape extending in the direction of the longitudinal axis of the spacer; and - securing means configured to engage the trough of the spacer to secure the second attachment side relative to the first attachment side, the interspinous process spacing device being characterized in that the trough comprises: -- a proximate end positioned near the proximate end of the spacer; -- a distal end positioned near the distal end of the spacer; and -- a pair of angled sidewalls extending from the proximate end of the trough in the direction of the longitudinal axis of the spacer and from the posterior surface of the spacer to a bottom surface of the trough, wherein the angled sidewalls taper inward toward the longitudinal axis of the spacer in a direction from the proximate end of the trough to the distal end of the trough. - a first attachment side; - a second attachment side; - a spacer extending from the first attachment side and slideably insertable through a spacer slot formed in the second attachment side, wherein the spacer has an elongated shape defining a longitudinal axis of the spacer and is adapted to be positioned between a spinous process of a first vertebra and a spinous process of an adjacent second vertebra, and wherein the spacer comprises: -- a proximate end adjacent the first attachment side; -- a distal end opposite the proximate end in a direction of the longitudinal axis of the spacer; and -- a trough formed in a posterior surface of the spacer, wherein the trough has an elongated shape extending in the direction of the longitudinal axis of the spacer; and -- a proximate end adjacent the first attachment side; -- a distal end opposite the proximate end in a direction of the longitudinal axis of the spacer; and -- a trough formed in a posterior surface of the spacer, wherein the trough has an elongated shape extending in the direction of the longitudinal axis of the spacer; and - securing means configured to engage the trough of the spacer to secure the second attachment side relative to the first attachment side, -- a proximate end positioned near the proximate end of the spacer; -- a distal end positioned near the distal end of the spacer; and -- a pair of angled sidewalls extending from the proximate end of the trough in the direction of the longitudinal axis of the spacer and from the posterior surface of the spacer to a bottom surface of the trough, wherein the angled sidewalls taper inward toward the longitudinal axis of the spacer in a direction from the proximate end of the trough to the distal end of the trough.