Among patients with spondylolisthesis and lumbar spinal stenosis, laminectomy with fusion was associated with modestly greater improvement in physical health–related quality of life than laminectomy alone but not with significantly greater reduction in disability related to back pain. The increased use of the lumbar spinal fusion procedure in the United States, along with the wide variation in practice, is attracting interest from multiple stakeholders, including patients, physicians, payers, and policymakers. In a report published in 2014, spinal fusion (465,000 hospital-based procedures in 2011) accounted for the highest aggregate hospital costs ($12.8 billion in 2011) of any surgical procedure performed in U.S. hospitals. 1 The randomized, controlled Spine Patient Outcomes Research Trial (SPORT) showed that surgery was superior to nonoperative care for the management of lumbar degenerative spondylolisthesis. 2 In SPORT, most patients in the surgical group were treated by means . . .