Open Versus Minimally Invasive Spine Surgery Remains a Global Question – A Commentary on “Open Versus Minimally Invasive Spine Surgery in the Treatment of Single-Level Degenerative Lumbar Spondylolisthesis: An AO Spine Global Cross-Sectional Study”
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The optimal treatment of degenerative lumbar spondylolisthesis (DLS) remains controversial. Many surgeons advocate for decompression alone while others prefer an instrumented or noninstrumented fusion. This debate intensified with the publication of 2 randomized control studies in the New England Journal of Medicine in 2016; the SLIP (Spinal Laminectomy versus Instrumented Pedicle Screw) study [1] and the SSSS (Swedish Spinal Stenosis Study) study [2]. Both were well designed and executed randomized control trials with differing conclusions regarding the benefits of lumbar fusion for DLS. Complicating the conversation is the exact technique used to achieve surgical goals. The past few decades have seen technological advancements including 3-dimensional navigation, endoscopy, tubular retractors, robotics and more which have allowed many fusion surgeries to be performed with less soft tissue injury, lower blood loss and shorter hospital stays as compared to traditional open approaches. However, the choice of technique (open vs. minimally invasive [MIS]) for any given case ultimately depends on the surgeons’ comfort with technique as well as the patient’s clinical and radiographic picture.
The current issue of Neurospine features a report discussing the results of a cross-sectional online survey of AO Spine members exploring the trends in open versus MIS surgery as the preferred techniques for the treatment of 3 different cases of degenerative spondylolisthesis. The cases presented to the surveyed members were all non-isthmic spondylolisthesis at L4–5 with varying degrees of stenosis and instability. Surgeons answered what their preferred treatment was for each case with a multitude of possible options. They could opt for decompression alone or an instrumented fusion (open or MIS). Demographic information of the surgeons was collected including age, geography, fellowship experience, surgical specialty, years in training and their own surgical volumes of DLS cases. There was a relatively wide global distribution of surgeons: North America (8.6%), Latin America (16.2%), Europe & Southern Africa (33.4%), Middle East & North Africa (10.9%), Asia-Pacific (30.9%). The survey results revealed that open surgical techniques were the preferred approach in all 3 cases (58.8%, 57.3%, and 42.4%, respectively), particularly in cases involving central and bilateral foraminal stenosis. Over 80%–90% of respondents opted for an instrumented fusion procedure of some type for each case. In the surveys where surgeons recommended decompression without fusion, there was a slight predominance of MIS technique (including endoscopy) over traditional open laminectomy.
Further analysis showed that MIS options were more popular with younger surgeons and those with spine fellowship training. Older surgeons and those who had been in practice more than 11–15 years were more likely to choose traditional open approaches. And neurosurgeons were more likely to choose MIS options as compared to orthopedic surgeons. There are many possible factors which could explain these trends. Among them, younger surgeons have been exposed to more MIS spine surgery during their training and have an increased comfort level with the techniques. And perhaps the neurosurgical proclivity towards MIS is due to their comfort with microsurgery in intracranial surgery.
Geographic differences also bore statistical significance in surgical choices: lateral lumbar interbody fusion (LLIF) was significantly more common in North America than other regions, while MIS was preferred in the Asia-Pacific and Latin American regions. The authors recognized that there was a relatively small percentage of respondents from North America (8.6%) in the entire study. The survey did separate LLIF and anterior lumbar interbody fusion from “MIS” techniques – although these anterolateral approaches certainly can be considered minimally invasive and falling under the MIS umbrella.
Lewandowski et al. [3] investigated a similar question of regional differences in the acceptance of MIS techniques. Their opinion-based survey was conducted through multiple online platforms and found that the perception of MIS as mainstream in their regions was highest in Asia and South America as compared to North America and Europe. The survey also queried if the surgeons use these MIS techniques in their practices. Interestingly, the analysis demonstrated that rate of implementation of MIS techniques in surgical practice reported by spine surgeons was universally higher than the perceived acceptance rates of MIS into the mainstream in their region. This highlights the intercalation of MIS spine surgery globally – despite many surgeons feeling it is not accepted across their area.
There is high quality evidence that surgical treatment of patients with DLS is beneficial [4]. And multiple studies over the past 2 decades have demonstrated comparable outcomes of MIS lumbar fusion as compared to open approaches, with perhaps some benefits in morbidity, blood loss and hospital length of stay [5]. Chan et al. compiled the evidence regarding the management of lumbar spondylolisthesis into a systematic review to help guide surgeons as to the best evidenced-based treatment [6]. The guidelines could not clearly recommend one fusion technique over another. Future, longer-term follow-up on these relatively newer fusion techniques certainly may elucidate more favorable surgical techniques. However, given the challenges in completing randomized control trials in spine surgery, the field may never get a clear answer.
The cross-sectional study [7] detailing the variety of surgical options for DLS chosen by different AO members is not intended to define which surgery should be done based on the surgeons’ region or experience. Rather, it emphasizes the growing number of options available. The question as to what the optimal surgery is to treat DLS may never be answered – but a continued debate amongst surgeons will propel the field forward. And clearly, this debate is a global one.
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Conflict of Interest
The author has nothing to disclose.