Background The reference surgical procedure for the treatment of lumbar disc herniation is open microdiscectomy. Minimal invasive discectomy with tubular retractors is hypothesised to cause less tissue damage and result in lower blood loss, less postoperative pain and faster recovery. We previously reported our 1 and 2-year results, and found no better outcomes of tubular discectomy compared with open microdiscectomy. Until now, no studies on tubular discectomy have reported results with more than 2 years of follow-up. Studies with long-term follow-up are required to determine if clinical outcomes are sustained and to assess specific long-term outcomes such as reoperation rate and iatrogenic low back pain due to impaired spinal integrity. The aim of this study is to evaluate the 5-year results of tubular discectomy compared with conventional microdiscectomy.

Methods The study was designed as a double-blind randomised controlled trial. 325 patients with a symptomatic lumbar disc herniation were randomly allocated to tubular discectomy (166 patients) or conventional microdiscectomy (159 patients). Repeated standardised follow-up measurements were performed at 2, 4, 6, 8, 12, 26, 38, 52, 78, 104, 156, 208 and 260 weeks after randomisation. Main outcomes are the Roland-Morris Disability Questionnaire for Sciatica (RDQ), Visual Analogue Scale for leg pain and low back pain, self-perceived recovery and reoperation incidence.

Results There was no clinically significant difference between tubular discectomy and conventional microdiscectomy regarding the main clinical outcomes at any time point during the 5 years of follow-up. RDQ scores at 5 years were 4.3 (95% CI 3.3 to 5.2) in the tubular discectomy group and 3.4 (95% CI 2.4 to 4.5) in the conventional microdiscectomy group. The mean difference of 0.9 (95% CI −0.6 to 2.2) was not significant. Mean differences for leg pain and back pain were 0.2 (95% CI −5.5 to 6.0) and 0.4 (95% CI −5.9 to 6.7), respectively. 77% of patients allocated to conventional discectomy reported complete or near-complete recovery of symptoms compared with 74% of patients allocated to tubular discectomy (p=0.79). The reoperation rate was 18% in the tubular discectomy group and 13% in the conventional discectomy group (p=0.29).

Conclusions Long-term functional and clinical outcome did not differ between patients allocated to tubular discectomy and conventional microdiscectomy. Primary and secondary outcome measures did not support the hypothesised advantages of tubular discectomy over conventional microdiscectomy.

Trial registration number ISRCTN51857546.