Surgery with disc prosthesis may produce better outcomes than multidisciplinary rehabilitation for patients with chronic low back pain

Hellum C et al (2011) Surgery with disc prosthesis versus rehabilitation in patients with low back pain and degenerative disc: two year follow-up of randomised study. BMJ 342: d2786 doi:10.1136/bmj.d2786. [Prepared by Margreth Grotle and Kåre Birger Hagen, CAP Editors.]

Question: What are the effects of surgery with disc prosthesis compared to multidisciplinary rehabilitation for patients with chronic low back pain?

Design: A single blind randomised controlled multicentre trial.

Setting: Five university hospitals in Norway.

Participants: Men and women 25-55 years with low back pain as the main symptom for at least one year, physiotherapy or chiropractic treatment for at least six months without sufficient effect, a score of at least 30 on the Oswestry disability index, and degenerative intervertebral disc changes at L4/L5 or L5/S1, or both. Patients with nerve root involvement were excluded. Randomisation of 179 participants allocated 86 patients to surgical treatment and 87 to rehabilitation.

Interventions: Rehabilitation consisted of a cognitive approach and supervised physical exercise directed by physiotherapists and specialists in physical medicine and rehabilitation. Intervention was standardised and organised as outpatient treatment in groups; it lasted for about 60 hours over 3-5 weeks. Follow-up consultations were conducted at 6 weeks, 3 and 6 months, and 1 year after the intervention. Surgical intervention consisted of replacement of the degenerative intervertebral lumbar disc with an artificial lumbar disc. Surgeons were required to have inserted at least six disc prostheses before performing surgery in the study. Patients were not referred for postoperative physiotherapy, but at 6 weeks follow-up they could be referred for physiotherapy if required, emphasising general mobilisation and non-specific exercises.

Outcome measures: The primary outcome was the Oswestry Disability Index (ODI, 0-100 scale) at 2 years. Secondary outcomes included low back pain (0-100 VAS), SF-36, and EQ-5D scores.

Results: The drop-out rate at 2 years was 15% in the surgical arm and 24% in the rehabilitation arm. At 2 years follow up, the between group differences (95% CI) in favour of the surgical treatment were -8.4 (-13.2 to -3.6) for ODI, -12.2 (-21.3 to -3.1) for pain, and 5.8 (2.5 to 9.1) for SF-36 physical health summary. No differences were found in SF-36 mental health summary or EQ-5D.

Conclusion: Surgery with disc prosthesis produced significantly greater improvement in variables measuring physical disability and pain, but the difference in ODI between groups did not exceed the pre-specified minimally important difference of 10 points, so it is unclear whether the observed changes were clinically meaningful.