5 RCTs assessed the rate of retrograde ejaculation in 508 men with symptomatic single-level lumbar degenerative disc disease with up to Grade 1 spondylolisthesis. Patients underwent anterior lumbar interbody surgery with stand-alone anterior implants at either L4-5 or L5-S1, with or without recombinant human bone morphogenetic protein-2 (rhBMP-2). The procedure was done either through transperitoneal approach or through the retroperitoneal approach. After 2 years of follow up, the use of rhBMP-2 was associated with a higher incidence of RE, but not statistically significant. A transperitoneal approach had a higher risk of adverse events.