173 patients with chronic low back pain due to single-level lumbar degenerative disease were randomized to either total disc replacement or a multidisciplinary rehabilitation program. Patients were followed up for 8 years after treatment for outcome on the Oswestry Disability Index (ODI), as well as pain, quality of life, occupational status, satisfaction, drug use, complications and additional back surgery. After 8 years, the mean improvement in ODI score from baseline significantly favoured TDR over MDR in both intention-to-treat and per-protocol analyses, though the size of the difference between groups was suggested to be below a clinically important difference threshold of 10 points.