Question:
In patients with sciatica caused by lumbar disc herniation, how does tubular discectomy compare with conventional microdiscectomy?
Design:
Randomized (allocation concealed), blinded (patients and outcome assessors), controlled trial with 1-year follow-up.
Setting:
Seven general hospitals in the Netherlands.
Patients:
328 patients, 18 to 70 years old, who had sciatica due to lumbar disc herniation lasting >6 to 8 weeks and refractory to conservative treatment were enrolled. Exclusion criteria included small disc herniations lacking distinct nerve root compression, cauda equina syndrome, previous spinal surgery at the same disc level, spondylolisthesis, central canal stenosis, pregnancy, and somatic or psychiatric disease. Data were available at 1 year for 307 patients (94%), and 325 patients (99%) (mean age, 41 y; 53% men) were included in the analysis.
Intervention:
Patients were allocated to tubular discectomy (n = 167) or microdiscectomy (n = 161). During tubular discectomy, the skin was retracted and the guidewire and sequential dilators were placed at the inferior aspect of the lamina. A 14 to 18-mm working channel was introduced over the final dilator and was attached to the table. With use of microscopic magnification, the herniated disc was removed through the tubular retractor. Conventional microdiscectomy was performed by ipsilateral paravertebral muscle retraction. With use of microscopic magnification or a headlight loupe, the herniated disc was removed by the unilateral transflaval approach.
Main outcome measures:
The primary outcome was patient self-reported functional disability measured by the modified Roland-Morris Disability Questionnaire (RDQ) for sciatica (range, 0 to 23, with higher scores indicating worse outcome). Secondary outcomes were scores on the 100-mm visual analogue scale (VAS) for leg and back pain (with higher scores indicating worse pain), self-reported recovery, functional and economic scores (Prolo scale [a 4-point qualitative scale, with lower scores indicating worse functioning]), bodily pain and physical functioning scores (Short Form-36 [range, 0 to 100; with higher scores indicating less severe symptoms]), Sciatica Frequency and Bothersomeness Index scores (range, 0 to 6; with higher scores indicating greater frequency and bothersomeness), and complication and reoperation rates.
Main results:
Analysis was by intention to treat. The study had 90% power to detect a 4-point difference between RDQ scores in the first year after surgery. At 8 weeks, the mean RDQ score did not differ between the tubular discectomy and microdiscectomy groups (Table). At 1 year, there was a borderline significant difference (p < 0.05) favoring the microdiscectomy group (Table). Among the secondary outcomes, better scores occurred at 1 year with microdiscectomy in leg and back pain and in patient-reported recovery (Table). The groups did not differ for any other outcomes.
Conclusion:
In patients with sciatica caused by lumbar disc herniation, tubular discectomy was not different from conventional microdiscectomy in functional outcomes and showed less favorable results in patient-reported pain and recovery.
Tubular distraction systems have been developed to decrease the paraspinal muscular damage caused by stripping and retraction, thus decreasing postoperative pain and speeding recovery. Like many minimally invasive surgical advances, efficacy has not been established. This study by Arts and colleagues confirms the observations of three other similarly designed studies that showed no benefit of the tubular retractor system1-3.
The study design was robust and included sufficient numbers of patients to ensure that the results apply to similar patients seen by any orthopaedic surgeon. It is notable that the authors appropriately excluded patients with small herniations or other confounding variables such as cauda equina syndrome, instability, or previous surgery.
The goal of surgery is to remove the offending disc impinging on the neural structures and, when performed in patients with indicated cases, good results can be expected. The ultimate outcome is dependent on the nerve recovery and residual intervertebral disc derangement and most likely is not related to muscle damage from the approach. Muramatsu and colleagues showed no difference in postoperative magnetic resonance imaging of paraspinal muscle properties between tubular and conventional discectomy4. Other theoretical advantages of minimally invasive surgery, such as shortened hospitalization and lower rates of adverse events, were not observed.
In conclusion, although the clinical results of conventional microdiscectomy in this study were significantly better at one year, the differences were small and not likely to be clinically important. The current standard of care for patients requiring surgical treatment of lumbar radiculopathy secondary to a herniated disc is partial discectomy with use of an open technique under loupe or microscopic magnification.
References
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