Fusion in degenerative spondylolisthesis: how to reconcile conflicting evidence

The role of fusion in degenerative spondylolisthesis (DS) was hotly debated in the 1990s, until two studies were performed suggesting that patients undergoing fusion in addition to laminectomy had better outcomes and less progression of listhesis than patients undergoing laminectomy alone (1,2). These were single center studies that used rudimentary randomization techniques and generally subjective, surgeon-reported outcomes. While relatively high quality studies for the time, they would be viewed as no better than Level 2 evidence today. Based largely on the results of these studies, laminectomy and fusion became the standard treatment for DS, and over 95% of DS patients undergoing surgery in the United States now undergo a fusion (3). More recently, the role of fusion has been questioned, especially as less invasive decompressive techniques have been developed (4). As a result, two RCTs were performed comparing laminectomy to laminectomy and fusion, with the results recently published in the New England Journal of Medicine.