Fig. 1

CONSORT flow diagram. * Heart attack some days after randomization (n = 1), obvious exclusion criterion discovered some days after randomization (earlier large abdominal operation (n = 1)), degenerative change insufficient to satisfy inclusion criteria (n = 2) or present in more than two lower lumbar discs (n = 2)). # Changed their mind and declined surgery after randomization (3 had social reasons for not receiving treatment, 1 had work related economic reasons, and 5 wanted guaranteed success). & Changed their mind after randomization and did not attend the rehabilitation program (2 had work-related economic reasons, 1 was treated elsewhere with surgery for lumbar disc herniation, 1 had social reasons, and 2 needed to travel long distances/could not stay away from home). % Dropped out after total disc replacement (TDR) surgery (1 had serious complications with a vascular injury and leg amputation, 2 did not want to attend the follow-up and 1 could not be contacted after surgery). £ 6 patients dropped out during the rehabilitation program (1 did not find the program good enough, 1 had lumbar disc herniation during treatment and underwent microdiscectomi, 1 did not manage to go through the training program, 1 developed diabetes during or just before treatment, 1 had psychosocial reasons, and 1 had hypertension and the family doctor did not recommend training), 8 dropped out after completing the treatment (1 took part in another study, 1 patient did not complete the questionnaire, 1 patient moved, 1 patient died of cancer, 3 did not want to attend the follow-up, and there was 1 for whom the reason was unknown). $ Two patients underwent surgery with instrumented fusion before 2-year follow-up. ** One patient crossed over to surgery between 6 months and 1 year and five patients between 1 year and 2 years. Five patients underwent TDR surgery and one patient fusion. § Subjects relevant for analysis were patients with both a pre-treatment MRI and valid score for back pain, Oswestry Disability Index (ODI) score and data on work status at 2-year follow-up. Patients randomized to rehabilitation who crossed over and underwent TDR surgery before 2-year follow-up within (n = 5) or outside (n = 5) the study setting are analyzed in the surgery group, patients who refused TDR surgery and underwent rehabilitation were analyzed in the rehabilitation group (n = 2), according to as-treated principles. μ Refused surgery (n = 7), re-operated upon with a fusion (n = 2). ≠ Did not start the rehabilitation program (n = 7), received a primary fusion (n = 1). ¥ Randomized design (RCT) includes patients with MRI at both pre-treatment and 2-year follow-up. β Re-operated upon with a fusion. ∞ Crossed over to surgery (n = 5 to TDR and n = 1 to fusion), did not complete the rehabilitation program (n = 1)