CORR Insights®: Reoperation Rates of Microendoscopic Discectomy Compared With Conventional Open Lumbar Discectomy: A Large-database Study

Where Are We Now?

In patients with lumbar disc herniation, microendoscopic discectomy and open microdiscectomy are used to treat pain caused by lumbar radicular compression in patients whose symptoms persist despite medication and other nonsurgical interventions. Microendoscopic discectomy is being used more widely because it offers a shorter recovery period and its clinical results seem to be comparable to those of open microdiscectomy [2, 8], but whether the short-term benefits come at a cost in terms of longer-term problems (such as reoperations) remains unknown [4]. In particular, whether the smaller approach results in more-severe damage to the remaining disc has not been characterized, and the “microendoscopic” and “open” techniques include adaptations that have varied across studies on the topic. Thus, it is questionable whether comparing these two procedures in any broad sense based only on the reoperation rate will be sufficient to answer all the clinical questions we might have about these surgical approaches.

But it’s a start. The present study by Masuda et al. [7] is the first step in this direction; they compared microendoscopic discectomy against open discectomy and traditional microdiscectomy and found that the risk of reoperation was higher among patients who underwent microendoscopic discectomy than among patients who underwent an open discectomy or traditional microdiscectomy at a median follow-up of 4 years after surgery in a large group of patients. Based on this finding, surgeons should make an educated decision about which technique to use and inform their patients accordingly. Because techniques and instrumentation are developing rapidly, an analysis of outcome measures is of the utmost concern.

Where Do We Need To Go?

The key question is: When is microendoscopic discectomy or open microdiscectomy indicated, and for which patient, while minimizing the risk of reoperation and possibly improving the final functional result? With a thorough understanding of the benefits and limitations of the two main surgical treatment options for lumbar disc herniation, surgical intervention could be tailored to a specific patient. Neither of these techniques is the best solution in all patients with lumbar disc herniation, and ideally, surgeons should be experienced in both.

Both techniques rely on intraoperative fluoroscopy for initial localization of the disc and the needed trajectory [11]. The radiation exposure is clearly larger in microendoscopic discectomy. However, fluoroscopy delivers a two-dimensional image in one plane of orientation, and placement of guidewires during microendoscopic discectomy can be challenging because several punctures might be needed to position the guidewires adequately [1]. Three-dimensional navigation and robotic assistance can considerably improve accuracy during positioning [5, 9]. Additional benefits include less surgical time, decreased radiation exposure, less soft tissue damage, and fewer complications [9-11]. Navigation can be used not only for localization but also for improving the quality of discectomy and resection of a herniation. Microendoscopy and open microscopy are only able to show the surface of the structure in view. Three-dimensional navigation augments this perception with information about structures beyond our direct field of view [10]. This would allow the surgeon to achieve a more-precise orientation with the ability to protect neural structures and decompress the nerve root. Navigational systems can be based on MRI, CT, and fluoroscopy and can merge these data [3]. Merging of MRI and CT data enables the surgeon to see soft tissue and bony structures.

These systems also allow us to check the result of decompression intraoperatively, beyond the direct field of view in an endoscope or microscope. Retrospective studies have suggested that navigation-assisted spinal surgery can improve a patient’s treatment and outcome [6, 9]. However, the main disadvantages of using imaging navigation and robot assistance are the additional costs, training, and learning curve. Nonetheless, I believe that implementing navigation-assisted spinal surgery and robotic assistance will be the next step in improving the treatment of lumbar disc herniation [5].

How Do We Get There?

Microendoscopic discectomy and open microdiscectomy yield the same clinical outcome, but microendoscopic discectomy might result in an increased reoperation rate despite its benefits. Thus, a comparison of both methods in a standardized clinical setting is ethically defensible [2]. Although retrospective studies might be instrumental in indicating possible differences in outcome and complications between surgical techniques, only high-quality prospective studies focusing on the essential questions at hand will be able to determine the superiority of one technique over another. The first step would be to design a standardized protocol for lumbar disc herniation surgery using both techniques, including the parameters of recurrence at the same disc level and side; recurrence at additional levels; and short-term, mid-term, and long-term functional results. The implementation of a protocol supported by national, and ideally international, spine surgeons would enable us to start collecting data and perform analyses prospectively. With the expected rapid introduction of imaging navigation and robot assistance, these techniques should be evaluated further. Without a proper analysis, betting on one technique and losing precious information holds the risks of harming our patients and not offering the best treatment option.