Question: If the surgeon fuses vertebrae L2 through L5 posteriorly, how many units of arthrodesis should I claim? Michigan Subscriber Answer: You should report 22612 (Arthrodesis, posterior or posterolateral technique, single level; lumbar [with or without lateral transverse technique]) along with two units of +22614 (... each additional vertebral segment [list separately in addition to code for primary procedure]). Although this procedure involves four vertebrae (L2, L3, L4 and L5), the surgeon only fuses three separate levels, or interspaces (L2-L3, L3-L4 and L4-L5). Arthrodesis implies a fusion of a motion segment, which includes two adjacent vertebrae and the intercalary disc and/or facet joints (in other words, two segments and the interspace/joints between them). Additionally, the descriptors for 22600-22614 specifically refer to spinal "levels" rather than vertebrae.