A spinal implant system for placement between first and second spinous processes of adjacent vertebrae of a spine, characterized in that the system comprises: a hollow spacer having a longitudinal axis, a length along the direction of the longitudinal axis, a height, a width, a posterior side of a sidewall, a anterior side of the sidewall, and at least one slot along the length of the spacer separating the posterior side of the sidewall and the anterior side of the sidewall; a first superior lobe of a first extension having a height and a centerline along the first superior lobe height; a first inferior lobe of the first extension having a height and a centerline along the first inferior lobe height; and a second extension connected to the spacer, wherein the second extension includes a second superior lobe and a second inferior lobe; wherein when the system is in an installed condition on a patient, the spacer abuttingly engages the first spinous process and the second spinous process, the first superior lobe is spaced apart from the first inferior lobe in a direction along the height of the spacer, the first superior lobe centerline is spaced apart from the first inferior lobe centerline in a direction along the width of the spacer, and the first superior lobe and the first interior lobe are disposed on a same side of the patient's sagittal plane wherein the first superior lobe and the first inferior lobe as well as the second superior lobe and the second inferior lobe form a generally Z-shape when viewed along the longitudinal axis of the spacer, wherein the posterior side of the sidewall and the anterior side of the sidewall each comprise an inner surface and an outer surface, and wherein the spacer comprises at least one opening other than the at least one slot to promote tissue ingrowth. a hollow spacer having a longitudinal axis, a length along the direction of the longitudinal axis, a height, a width, a posterior side of a sidewall, a anterior side of the sidewall, and at least one slot along the length of the spacer separating the posterior side of the sidewall and the anterior side of the sidewall; a first superior lobe of a first extension having a height and a centerline along the first superior lobe height; a first inferior lobe of the first extension having a height and a centerline along the first inferior lobe height; and a second extension connected to the spacer, wherein the second extension includes a second superior lobe and a second inferior lobe; wherein when the system is in an installed condition on a patient, the spacer abuttingly engages the first spinous process and the second spinous process, the first superior lobe is spaced apart from the first inferior lobe in a direction along the height of the spacer, the first superior lobe centerline is spaced apart from the first inferior lobe centerline in a direction along the width of the spacer, and the first superior lobe and the first interior lobe are disposed on a same side of the patient's sagittal plane wherein the first superior lobe and the first inferior lobe as well as the second superior lobe and the second inferior lobe form a generally Z-shape when viewed along the longitudinal axis of the spacer, wherein the posterior side of the sidewall and the anterior side of the sidewall each comprise an inner surface and an outer surface, and wherein the spacer comprises at least one opening other than the at least one slot to promote tissue ingrowth.