Vanderbilt University researchers have compared the outcomes and costs of minimally invasive TLIF versus open TLIF in over 100 patients with low grade spondylolisthesis. Parker et al showed that MIS TLIF can lead to comparable outcomes with accelerated return to activity and direct and indirect cost savings of $1,758 and $8,474, respectivley.1
"The question now becomes, how can we continue to push this innovation forward to a place where the instrumentation and techniques are used more widely so they become less expensive relative to the standard instruments," says David Hart, MD, director of the Neurosurgery Spine Center at University Hospitals Case Medical Center in Cleveland. Over the past decade, innovation in the spine field has exploded to the point where several new technologies are on their way to becoming a standard of care.
"We have gone from performing all our spine surgeries with inpatient hospital stays to performing them as outpatient procedures," says Raed Ali, MD, an orthopedic spine surgeon at St. Jude Heritage Spine Center in Fullerton, Calif. "The most common outpatient procedures are percutaneous, arthroscopic (through a tube), and mini-incision approaches. Surgeons are even doing less invasive spinal fusions and device companies’ new product designs are making that easier."
One of the biggest challenges minimally invasive spine surgery faces is the learning curve, which can be daunting for experienced spine surgeons. "Surgeons are faced with the choice of taking time out of their practice to go to courses and learn the new techniques; or decide MIS isn't their thing," says Dr. Hart. "I think that challenge will fade away with the new generations of spine surgeons; over time that will drive the adoption of MIS techniques."
Newer innovations also face challenges with gathering enough data and information to prove effectiveness and show surgeons the benefits of new techniques. "If independent groups adopt newer technologies and collect their own data, they could prove their results," says Carl Lauryssen, MD, co-director of spine research and development at Olympia Medical Center in Los Angeles. "Unfortunately, funding is not available like it used to be for industry to sponsor clinical trials. The next best thing is for individual or multi-group surgeons to adopt these newer technologies and collect appropriate data to verify early success."
Minimally invasive transforminal decompressions are making strides forward for managing patients with spinal stenosis and stable grade 1 spondylolisthesis.
"There is a subset of patients who have spondylolisthesis but do not need to be fused and for which we can do a decompression with a device such as Baxano's iO-Flex to preserve stability," says Dr. Lauryssen. "An appropriate decompression can not only reduce the radicular systems and neurogenic claudication but also reduce back pain without a fusion, based on my experience and preliminary data from our clinical trial."
The decompression is achieved without sacrificing the stability of the facet joint. “Using iO-Flex, we are able to decompress ipsi and contralaterally through a unilateral microdiscectomy approach,” says Dr. Lauryssen. “Any other technique that does adecompression via a unilateral approach will result in significantly more compromised facet joints, risking instability and poor outcomes.”
Advances in the direct lateral approach are continuing to drive the adoption of this fast growing segment of the spine surgery market. "Shallow docking retractors, such as the VEO system, are a key step forward," says Dr. Ali. "What has been learned, generally, is that shallow docking techniques may decrease morbidity by minimizing postoperative thigh paresthesia symptoms, which allows the patients to recover and leave the hospital more quickly."
Advances in technology have also made it possible to perform less invasive surgery at L5/S1. Pre-sacral interbody fusion, which is the only new procedure in spine to obtain a Category I Code in the last five years, shows positive short-term outcomes with low complications, thanks to its minimally invasive approach.
A 2013 study from Yale University researcher Dr. Peter Whang compared pre-sacral interbody fusion to open anterior lumbar interbody fusion in 96 patients. Dr. Whang found similar rates of fusion — 85 percent for AxiaLIF and 79 percent for ALIF. The complication rate was 21 percent and 33 percent for pre-sacral interbody fusion and ALIF, respectively. Of note there were no bowel injuries in the pre-sacral interbody fusion group and there was one iliac laceration in the ALIF group.2
"We've definitely shown reduced blood loss, infection rate, less narcotic use and shorter hospital stays with these procedures," says Dr. Hart. "With AxiaLIF, the fact that you don't violate any of the muscular or ligamentus structures of the spine to get to your target is a huge benefit. That's what appeals to me — you have the natural access corridor to get to the disc without damaging the patient's anatomy."
Reducing hospital stays will go a long way in lowering the cost of care. "I think the costs for spine surgery are outrageous — most spine surgeons are aware of this — but patients aren't," says Dr. Ali. "The percentage of costs associated with the hospital stay makes up the majority of overall costs for the procedure. If we can decrease the length of stay we can decrease the financial burden."
Smith etal compared the outcomes and charge data for 202 patients who underwent either an open approach to lumbar interbody fusion or minimally invasive interbody fusion (single-level direct lateral or a two-level combination of direct lateral and pre-sacral approach). The researchers found a lower level of complications in the minimally invasive group along with a 10 percent and 13.6 percent reduction in charges respectively compared to the open approach.3
Despite the potential for lower-cost care, minimally invasive spine surgery still has several challenges as a field. Payers — government and private — looking to cut costs have tightened indications for covering spinal procedures. Cost pressures and the medical device excise tax have also lowered the amount of money available for device companies to fund new innovations.
"There is going to be less money to develop new and better products," says Dr. Ali. "That's going to be one of the challenges that has to be overcome by surgeons and industry together. There has to be a team effort to support and drive innovation to improve techniques and minimize the scope of surgery."
Despite the financial challenges, Dr. Ali still sees immense opportunity for development in the spine field. "In general that's what I love about the spine field — it's not static," he says. "In spine surgery, we've seen revolutionary changes. I'm excited about the scope of possibilities in spine, many of which we haven't even realized yet."
Combining minimally invasive procedures with computer navigation has potential for improving procedures in the future.
"So far, most of the spinal navigation systems have been at best ridiculously expensive and clunky to use," says Dr. Hart. "But we are starting to see some real progress with that. Registration and reference tracking has been the problem in the past because the whole point is to make as few and as small of incisions as possible; but the reference tracker requires a separate incision over the spine or iliac crest, which defeats the purpose. There are companies trying to develop techniques for navigation without the incisions in the future."
1. Parker, S.L., Mendenhall, S.K., Shau, D.N., Zuckerman, S.L., Godil, S.S., Cheng, J.S., McGirt, M.J. (2013 Jan). Minimally Invasive versus Open Transforaminal Lumbar Interbody Fusion for Degenerative Spondylolisthesis: Comparative Effectiveness and Cost-Utility Analysis. World Neurosurg. pii: S1878-8750(13)00102-2. doi: 10.1016/j.wneu.2013.01.041.
2. Whang, P.G., Sasso, R.C., Patel, V.V., Ali, R.M., Fischgrund, J.S. (2013 Dec). Comparison of Axial and Anterior Interbody Fusions of the L5-S1 Segment: A Retrospective Cohort Analysis. Journal of Spinal Disorders and Techniques, 26 (8), 437-443.
3. Smith, W.D., Christian, G., Serrano, S., Malone, K.T. (2012). A comparison of perioperative charges and outcome between open and mini-open approaches for anterior lumbar discectomy and fusion. Journal of Clinical Neuroscience, 19, 673-680.
This article is sponsored by Baxano Surgical.
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