 Laminotomies were then performed at L4-L5 and L5-S1 in a similar fashion using Midas Rex drill with AM8 bit, inferior portion of lamina below and superior portion of lamina above, and the medial facet was drilled down to the thin shelf of bone. 
Laminotomies were then performed at L4 - L5 and L5 - S1 in a similar fashion using Midas Rex drill with AM8 bit , inferior portion of lamina below and superior portion of lamina above , and the medial facet was drilled down to the thin shelf of bone .