179 patients were randomized to determine the efficacy of disc prosthesis surgery compared to non-operative rehabilitation in the treatment of low back pain. Pain and disability outcomes were evaluated over 2 years, along with return to work and mental health criteria. Results indicated that pain and disability measured through the Oswestry Disability Index (ODI), visual analog scale, and SF-36 physical component summary were significantly improved patients who had undergone surgery compared to patients who had received rehabilitation only. The clinical importance of ODI reduction can be debated, however.