Tubular discectomy for the treatment of lumbar disc herniation : new standard or transient fashion? : Results of a double-blind randomised controlled trial
Arts, M.P.
Citation
Arts, M. P. (2010, September 23). Tubular discectomy for the treatment of lumbar disc herniation : new standard or transient fashion? : Results of a double-blind randomised controlled trial. Retrieved from https://hdl.handle.net/1887/15975
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Vatnajokull Glacier, Iceland
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Summary
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Chapter 11Radicular leg pain caused by lumbar disc herniation affects many people worldwide and the natural course is favourable in most cases. Patients are offered surgery whenever disabling leg pain persists. Presently, unilateral transflaval microdiscectomy is the golden standard for surgical treatment with which all new techniques should be compared prior to implementation on a large scale. Minimally invasive spine surgery has been popu larised in recent years. The rationale behind less invasive techniques is reduced muscle trauma, less postoperative low- back pain, shorter hospitalisation and faster resumption of work and daily activities.
In 1997 Fo ley and Sm ith introd uced the m uscle-spl itting m in imally invasive tu bu lar approach to replace the conventional muscle-stripping approach. Presently, thousands of people have been operated on worldwide and the technique has proven to be safe and effective. However, large randomised controlled trials of tubular discectomy versus conventional microdiscectomy have not been performed yet. This thesis outlines the results of a double-blind multi centre trial (the Sciatica-MED trial) in which tubular discectomy was compared with unilateral transflaval microdiscectomy in a parallel group design.
Chapter 1 gives a short general introduction and some historical facts about sciatica in general and lumbar disc surgery in particular. Wide laminectomy with transdural removal of the herniated disc has been refined into less invasive approaches. Following general surgery, a shift to minimally invasive surgery of lumbar herniated discs began. One of the developments is the muscle-splitting technique of tubular discectomy by means of the METRx system. The objective and outline of the thesis are described.
Chapter 2 describes a national survey held among Dutch spine surgeons of their daily practice of patients with lumbar disc herniation. In addition, surgeon's expectations of various conventional and minimally invasive techniques regarding leg pain, low-back pain, recurrent disc herniation, and complications are evaluated. Tubular discectomy already belonged to the armamentarium in some neurosurgical and orthopaedic clinics although most of the surgeons performed unilateral transflaval microdiscectomy with headlight-Ioupe or microscopic magnification. This golden standard was expected to be most effective while minimally invasive techniques were expected to be less effective with higher recurrence rates but reduced postoperative low-back pain.
In Chapter 3 the design of the Sciatica-MED trial, a double-blind (cost-) effectiveness study, is presented. To answer the question of whether tubular discectomy is more (cost-) effective than unilateral transflaval microdiscectomy, at least 300 patients with lumbar disc herniation have to be randomised. To enrol enough patients, 14 surgeons from 7 general hospitals participated in the study after approval of the protocol by the medical ethics committees.
Summary
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177The l-year clinical results are presented in Chapter 4. Use oftubular discectomy compared with conventional microdiscectomy did not result in a statistically significant functional improvement as measured by the Roland Disability Questionnaire for Sciatica. The median time until complete recovery was 2 weeks, irrespective of the allocated surgical treatment.
Both groups reported relief of leg pain and low-back pain, although the differences favoured the conventional microsurgery group. However, these differences were small and not clinically relevant. At 1 year after surgery, 69% of patients who underwent tubular discectomy versus 79% of those treated with conventional surgery reported complete recovery.
Chapter 5 describes the cost-benefit analysis of the Sciatica-MED trial. Similar time until recovery makes tubular discectomy unlikely to be cost-effective compared with conventional microsurgery. QALYs during all four quarters and according to all benefits were not statistically different between tubular discectomy and conventional microdiscectomy. The sum of the healthcare costs and the non-healthcare costs resulted in a nonsignificant difference of € 1302 in favour of conventional microdiscectomy.
Certain anamnestic, neurological, and radiological variables might facilitate decision- making between tubular discectomy and conventional microdiscectomy for the treatment of patients with herniated disc-related sciatica. Chapter 6 describes the subgroup analysis of predefined variables and their interaction with the treatment strategy. Patients with contained disc herniation recovered more slowly when they underwent tubular discectomy compared to those who underwent conventional microdiscectomy. No difference in rate of recovery between treatment strategies was found for patients with disc sequestration. Based on these results, patients with a sequestrated disc may choose either tubular discectomy or conventional microdiscectomy, depending on the patients' or surgeons' preferences, but those patients with a contained disc herniation may not be suitable for tubular discectomy.
The 2-year results (Chapter 7) are similar to the l-year results and no significant differences in scores on the Roland Disability Questionnaire for Sciatica were documented.
Patients treated with tubular discectomy reported more leg pain and more low-back pain, although the differences were small and not clinically relevant. At 2 years, 71% of the patients assigned to tubular discectomy reported good recovery versus 77% of the patients assigned to conventional microdiscectomy. Within 2 years after surgery, 15% of tubular discectomy group and 10% of conventional microdiscectomy group needed reoperation, mainly due to recurrent disc herniations.
Muscle trauma is quantified by the release ofthe enzyme creatine phosphokinase (CPK) in serum and reaches a maximum on 1 day after surgery. Postoperative low-back pain is one of
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Chapter 11the main problems after spine surgery and therefore it seems important to limit muscle injury.
The concept of minimally invasive spine surgery implies less tissue trauma, reduced low-back pain, and faster recovery. Chapter 8 describes a clear dose-response relationship between CPK and the extent of surgical invasiveness. Postoperative CPK elevation was influenced by the invasiveness of surgery, duration of surgery, spinal localization, posterior approach, revision surgery, and preoperative level of CPK. Nonspinal intracranial surgery was also associated with a CPK increase. Whether minimally invasive surgery is related to reduced muscle trauma and CPK level is controversial and, therefore, serum samples were taken from a subgroup of patients participating in the Sciatica-MED trial. In addition, the cross sectional area of the multifidus muscle and the multifidus atrophy grade were examined on the postoperative MRI at 1 year (Chapter 9). No statistically significant differences between tubular discectomy and conventional microdiscectomy were found in terms of CPK ratio and grade of multifidus muscle atrophy.
CONCLUSIONS
Although the minimally invasive technique of tubular discectomy seemed to be an attractive surgical method for treating lumbar disc-related sciatica, the data of the Sciatica-MED trial do not support a superior outcome compared with conventional microdiscectomy. Patients undergoing tubular discectomy reported similar functional improvements compared with conventional microdiscectomy, although they fared worse with regard to leg pain and low- back pain and fewer patients reported complete recovery during follow-up. These modest differences were not clinically relevant for the patients and do not warrant the transition from conventional microdiscectomy to less invasive approaches. Therefore, decision-making concerning the surgical strategy for patients with lumbar disc herniation should be based on the preferences of patients and surgeons rather than the overly optimistic argument of "small is better" (Chapter 10).
