March 18, 2015
14 min read

Minimally invasive spine surgery effective for many indications, but difficult to learn

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Techniques and procedures for minimally invasive surgery of the spine have developed considerably in recent decades and have since become more popular among spine surgeons, in some cases even more so than the traditional open approaches, according to sources who spoke with Spine Surgery Today.


Figure. Gary Ghiselli, MD, has found minimally invasive spine surgery is cost effective, but urged caution with all new surgical innovations.

Source:Laura Kinser

Gary Ghiselli, MD, said he finds minimally invasive surgery (MIS) of the spine more cost-effective than open surgery. It does more to address the quality of life for patients during the immediate recovery period, “as well as the long-term viability of the muscles and tissues overlying the spine,” he said.

With experience, published studies have shown complication rates can be equivalent to, but usually less than those encountered with traditional open approaches, according to Ghiselli.

“As such, if the same surgical procedure can be performed to the same technical degree with less tissue damage, then it makes logical sense that the effectiveness and surgical outcomes should be at least equivalent, but probably superior,” Ghiselli, of Denver, said. “There are many published studies that compare the effectiveness of MIS surgery with traditional open surgery that support this statement. Opponents of MIS opine that ‘traditional’ open surgery allows better exposure and access, as well as a more technically precise operation than can be performed with a MIS approach. The evidence simply does not support that statement,” Ghiselli told Spine Surgery Today.

Improved outcomes, shorter stays

Minimally invasive surgery of the spine is “the mantra of all spine surgeons” who want to benefit from the current trend toward MIS, according to Anthony T. Yeung, MD, of Phoenix. When performed well, minimally invasive spine surgery has greater patient satisfaction, improved outcomes, shorter hospital stays or can be performed safely and more efficiently in an ambulatory surgery center, he said.

Anthony Yeung

Anthony T. Yeung

However, MIS of the spine is not just simply about using smaller incisions, but a combination of techniques and the mastering of a learning curve that comes with many minimally invasive spinal surgeries, Yeung said.

“For patients, the results are dependent on seeking out surgeons who have overcome the learning curve, best overcome when the surgeon has some formal training. Most patients, however, should benefit from the trend toward minimally invasive surgery in spine surgical interventions,” he told Spine Surgery Today.

Broad definitions

Minimally invasive surgery is a broad term that represents surgeons attempting to perform surgeries with less trauma to the soft tissues and using smaller incisions, according to Jeffrey C. Wang, MD, of Los Angeles, who told Spine Surgery Today, “This spans the spectrum from doing small microsurgeries with smaller incisions and retractors, all the way to doing large deformity cases using multiple smaller incisions that span a large area of the spine. It is more of a philosophy. I see many surgeons who do some variety of MIS surgeries, which I believe will grow over time.”

There was a time, however, when spine MIS techniques first came out that Wang used them for nearly every case.

Jeffrey C. Wang

Jeffrey C. Wang

“Then I went away from that because I ended up taking a lot of hardware out…Some of the patients did very well, but then some had hardware pain where we had to go back in and I had to take the hardware out,” Wang said.

At that point he said he had to rethink the advantages of MIS based on the need for a second surgery in some of those cases and the time it took to perform multi-level decompressions via MIS surgery.

“The time probably is not worth it when I can do it quicker just open or even through smaller incisions using open techniques,” Wang said.

Defining MIS

“MIS runs the gamut from people using small retractors and small incisions with the microscope to using it for decompressions. I do that a lot,” Wang said. “I use the same MIS approaches for microdecompressions using very small incisions and things like that, but in certain situations I do not think MIS is appropriate, at least in my practice,” said Wang.


The broad spectrum of possible MIS techniques for the spine allow for a number of different instruments to be used during a procedure, however. Some surgeons prefer an endoscope for MIS procedures of the spine because it allows for a 2-dimensional visualization of the procedure, Wang said.

Both the endoscope and microscope can facilitate good surgical outcomes, according to Wang.

“I prefer the microscope where I am looking at it directly and have the 3-dimensional perception of the anatomy. With the lighting of the microscope and the ability to zoom into the field, the microscope works better for me. However, the endoscope allows potentially a greater variability of visualization angles. There are endoscopes that are made to look into crevices and nooks and crannies that allow us to better look around corners. This way of using the endoscope is a way to extend the visualization,” he said.

Lasers may be ineffective

Spine MIS implants are becoming popular with orthopedic surgeons and neurosurgeons and can offer potential benefits for patients, Wang said.

Another tool surgeons now use for MIS procedures is the laser. But, although it is a powerful instrument when used to smooth out a disc, there is concern that it can possibly damage nearby tissue, he said.

“I think some patients like the sound of the laser and I hear questions about it all the time. There are some uses for it, but I prefer not to use it for my current practice. I like some of the newer implants being designed for MIS approaches. These types of retractors and instruments are critical for MIS surgery and make it much easier. Recently, fusion implants are being designed which allow us to do these surgeries more easily. I see these as advances which will only get better with time. An example of this is a fusion implant that allows an interbody cage to be implanted more easily with the newer systems. These implants represent a continually evolving improvement for all MIS surgeons,” he said.

Based on Yeung’s experience, lasers can actually provide good outcomes when used for certain MIS procedures and they can be cost-effective, as well.

“A laser is just a surgical tool that is especially useful when its delivery is done under endoscopic visualization. It is a surgical tool that is very cost-effective when used for MIS-visualized decompression. It can be cost-effective even in the face of the initial expensive investment because judicious and proper use of the laser as a surgical tool, as opposed to its hype, will improve surgical decompression and ablation,” Yeung said.

Steep learning curve

According to Ghiselli, there are four goals for every type of surgery. The first goal is to fix the problem. The second goal is to do it safely. The third goal is to decrease the chance of the surgery will cause direct or indirect adverse long-term outcomes and the final goal is to perform the surgery with the least amount of trauma possible.

Surgeons who have a firm grasp on MIS techniques for the spine can achieve all four of those goals, Ghiselli said, but they need to be aware the learning curve for many of these spinal MIS techniques can be steep.

“In the best of circumstances, we can do all four. But, if we cannot do all four, we sacrifice the last one. Having a longer recovery is much less important than not addressing the problem adequately, safely or causing an adverse outcome,” Ghiselli said.

Proficiency takes time

The learning curve for MIS of the spine is an important factor just as it is with any surgical technique, John E. O’Toole, MD, MS, of Chicago, told Spine Surgery Today. The learning curve is directly proportional to the complication of the MIS technique, he said.


Typically, for the most routine minimally invasive spine surgical techniques, O’Toole said it typically takes between 20 and 30 surgeries to overcome the learning curve and truly become proficient in the procedure.

“When you start to perform multilevel fusion with instrumentation for conditions like spinal deformity and tumor, it becomes more complicated. The higher up you go in the hierarchy of spinal case complexity, the more experience you need,” O’Toole said. “We are continuing to push for mastery of minimally invasive surgery skills at the resident training level. For those practitioners who did not get that minimally invasive surgery experience during training, we work very hard to bring them up to speed through continuing education opportunities.”

John O'Toole

John E. O'Toole

Wang said in the past when some MIS procedures of the spine were first introduced, the learning curve was even more difficult and procedures took longer to complete than traditional open surgeries. But once surgeons became more proficient and additional MIS techniques were developed, the procedures ended up being completed more quickly and more efficiently.

“Things are now more sophisticated and we have more of a variety of MIS approaches. For some procedures, where smaller incisions are already used, the learning curve may not be worth it,” Wang said. “However, we are now applying these techniques to greater pathologies, and there are patients I see in my practice where an MIS approach has saved the patient an enormous open procedure. I see these in the revision situation or the more complex pathologies. When I find these patients, I look back and feel that the high learning curve was definitely worth it.”

Cost-effective solution

According to O’Toole, once the learning curve is overcome, MIS techniques for the spine can offer a cost-effective solution for many patients. He said it is a misconception among patients and surgeons that minimally invasive procedures of the spine are always more expensive than traditional open procedures. Some minimally invasive techniques can be more expensive on the surface due to equipment start-up costs, but when the actual direct and indirect costs are accounted for they are often less expensive.

Furthermore, O’Toole noted, MIS of the spine has changed the flow for patients and their experiences with spine surgery.

“It has reduced the length of stay, reduced complications, reduced blood loss. Recovery times are faster, patients are returning to normal activities faster, and ultimately all that translates into significant reductions in cost,” O’Toole said. “There are acute care costs at the time of the procedure, so the longer your length of stay is, obviously, the greater the costs associated with hospitalization, transfusions, narcotic requirements and in-patient services.”

The indirect costs and delayed costs are also reduced with MIS techniques in the spine. Patients undergoing those procedures have a shorter return to work time, so they are back to work sooner and require less postoperative assistance or care and home services, he said.

“As you strip away some of those problems, you see fewer indirect costs. Both the direct costs and indirect or delayed costs seem to go down as has been borne out in a number of publications now. It has changed the landscape entirely,” O’Toole said.

An article published in 2011 showed the average per patient cost for minimally invasive transforaminal lumbar interbody fusion was $14,183 and for open lumbar fusion procedure it was $18,633. According to a Journal of Spinal Disorders and Techniques study in 2012, the procedures can also be performed in outpatient centers, which results in shorter hospital stays. Costs on average were reported at $760 less for 1-level surgery and $2,106 less for 2-level surgery compared to open procedures for patients operated on at an outpatient center.


According to Yeung, many MIS procedures for the spine are cost-effective.

“It depends on how cost-effective and surgically effective the procedure is in an individual surgeon’s hands, taking into consideration the costs of expensive disposable and specialized equipment vs. simple surgical decompression vs. surgical stabilization using re-usable surgical equipment,” he said.

Deformity correction

In terms of pediatric cases, for some procedures, minimally invasive spine surgery does not offer the same benefits as can be seen with surgery performed for mature patients, Peter O. Newton, MD, of San Diego, told Spine Surgery Today.

For posterior pediatric deformity correction procedures, open techniques offer better outcomes than MIS techniques. Anterior MIS techniques of the spine using an endoscope can be effective, he said, but minimally invasive posterior techniques do not offer the same outcomes as open procedures.

Newton has extensive experience with MIS in the treatment of pediatric spinal deformity using an anterior endoscopic approach.

“Open posterior surgery generated greater correction and the recovery periods after those open surgeries really were not substantially longer than minimally invasive surgery for anterior procedures, so there was not a great savings in regards to hospital length of stay in comparison to open posterior procedures. Also, given current length of stay data for posterior adolescent idiopathic scoliosis correction of 4 days for many centers, I think we do not do any better than that with minimally invasive surgical anterior procedures,” Newton said. “Maybe there is a better minimally invasive surgical posterior approach that would be appropriate, but I do not think we have the efficacy proven in minimally invasive surgical posterior approaches for deformity that match the deformity correction and fusion rates for open procedures.”

Peter Newton

Peter O. Newton

With two basic approaches to the spine for deformity correction surgery — anterior and posterior — an anterior approach through the chest cavity with an endoscope can be beneficial for patients because the chest cavity offers a large space to work in, according to Newton, who said it is very straightforward MIS procedure. A posterior approach for the pediatric patient may not offer the same beneficial outcomes, he noted.

“The posterior approach in isolation as an MIS procedure has much greater challenges in the deformity world, particularly in the pediatric deformity world, and that makes it a little bit more of a challenge,” Newton said.

In terms of placing pedicle screws via MIS technique in pediatric patients, Newton said it is possible to do so as long as an imaging method is included in the procedure. If the procedure is CT-based or fluoroscopically based, it can work fairly well, he said.

However, according to Newton, problems can develop once pedicle screws are placed in a pediatric deformity patient.

“I do not think pedicle placement is problematic using a minimally invasive procedure, but the challenge is, and the concerns about efficacy are more related to how well you can connect the rod to those screws and how well can you can address deformity correction once the screws have been placed, and how well you can perform a posterior spinal fusion once those screws are placed,” he said.

Future of MIS

The future of MIS for spine procedures is bright, according to Ghiselli, particularly as more surgeons catch up with MIS techniques. Therefore, he predicted this segment of the surgical landscape will continue to see greater adoption and growth.

“Minimally invasive spine lumbar surgery has advanced significantly and there is continued innovation that continues to offer patients a quicker recovery and less trauma than a traditional approach. With time, MIS is proving to be a safe and efficacious option for certain patients and more patients are becoming aware of the availability of this technology. But, being cautious with the latest surgical innovations is always a good idea,” Ghiselli said.


He said neurosurgeons and orthopedic surgeons who want to embrace this technology need to be trained adequately and “suffer through” their own personal learning curves before they can promise patients safe and equivalent outcomes compared to more traditional open surgical techniques. – by Robert Linnehan


Rampersaud YR, et al. SAS Journal. 2011;doi:10.1016/j.esas.2011.02.001.

Wang MY, et al. J Spinal Disord Tech. 2012;doi:10.1097/BSD.0b013e318220be32.

For more information:

Gary Ghiselli, MD, can be reached at Denver Spine, 7800 East Orchard Rd., Greenwood Village, CO 80111; email:

Peter O. Newton, MD, can be reached at Pediatric Orthopedic and Scoliosis Center, 3030 Children’s Way, Suite 410, San Diego, CA  92123; email:

John E. O’Toole, MD, MS, can be reached at Rush University Medical Center, 1725 W. Harrison St., Suite 855, Chicago, IL 60612; email:

Jeffrey C. Wang, MD, can be reached at USC Spine Center, 1520 San Pablo St., Suite 2000, Los Angeles, CA  90033; email:

Anthony T. Yeung, MD, can be reached at Desert Institute for Spine Care, 1635 East Myrtle Ave., Phoenix, AZ 85020; email:

Disclosures: Ghiselli is a consultant to Biomet Spine, is a founder and has 8% ownership of Difusion Technologies. O’Toole is a consultant for Globus Medical and RTI Surgical. Newton is a consultant for and receives royalties from DePuy Synthes for the Expedium product line, both open and MIS implants and he has an intellectual property relationship for a MIS growth modulating tethering system and a royalty relationship for a MIS retractor, both with DePuy Synthes. Wang receives royalties from Stryker, Osprey, Biomet, Synthes, Seaspine, Amedica and Aesculap. He has personal investments or options in Bone Biologics, Alphatech, Axiomed, Amedica, Corespine, Expanding Ortho, Pioneer, Axis, Syndicom, VG Innovations, Pearldiver, Flexuspine, Fziomed, Benvenue, Promethean, Nexgen, Electrocore and Surgitech. He is on the boards of directors for AOSpine and receives honoraria plus travel to board meetings for Collaborative Spine Research Foundation and the North American Spine Society and receives travel to board meetings for the Cervical Spine Research Society. He reports fellowship support paid to the USC Department of Orthopaedic Surgery by the AO Foundation. Yeung receives royalties from Elliquence Inc., and from Richard Wolf as developer of the Yeung Endoscopic Spine System.


Does the perceived benefit of minimally invasive surgery (MIS) of the spine justify the extra cost typically associated with MIS implants and approaches?


Understand health economics

With the implementation of the Affordable Care Act, providers and hospitals are analyzing the cost of surgery with more scrutiny. In this discussion, diagnosis related groups (DRGs) are a critical component of understanding the true cost of care. While surgical implants and approaches play a role in the total cost of care, the actual measure for hospitals and insurance companies are the residual DRG costs. These costs include hospital floor and ICU charges, laboratory testing, pharmacy utilization, ancillary service requirements, etc.

Daniel Refai

Daniel Refai

Thus, the actual costs of an encounter such as a transforaminal lumbar interbody fusion (TLIF) operation are more complicated. The better question to ask is for the same patient with the same DRG and CPT code procedure, for example, TLIF at L4-5, is there a benefit to a minimally invasive surgery (MIS)-based procedure vs. a standard open procedure. The answer is likely yes, since despite the actual increased marginal cost of MIS implants and the associated costs of the approach, the value added of MIS-based procedures is better measured in the reduction in the length of stay, the decreased use of postoperative analgesia and rehabilitation services. I believe that understanding the health economics of the entire procedure from both a surgeon and hospital perspective will shed more insight into better decision making for our patients.

Daniel Refai, MD, is Associate Editor, Neurosurgery of Spine Surgery Today. He practices at the Emory Orthopaedic and Spine Center in Atlanta.
Disclosure: Refai reports no relevant financial disclosures. 


MIS benefits are real

This is a particularly fascinating question. Before addressing it directly, let us look at the inherent bias in its wording. First, consider the phrase “perceived benefits.” “Perceived” implies that surgeons and patients have a “gut feeling” that MIS has benefits, or that it seems reasonable to think MIS has benefits, but there are no real data supporting such benefits. This statement ignores and trivializes the now hundreds of peer reviewed manuscripts documenting less pain, less pain medicine requirement, less blood loss, less need for blood transfusion, less postoperative muscle atrophy, more normal postoperative biomechanics of the spine, lower infection rates, fewer complications, less physiologic stress, shorter ICU stays and shorter hospitalizations. Thus, I argue vociferously, this is not “perception.” The benefits of MIS are now abundantly proven fact.

Next, let us examine “extra cost.” This should be approached in several aspects. First, it is true MIS implants are more expensive than their “open” counterparts. Is that “justified” by the improved results obtained with MIS technique? Perhaps it is, in that additional delivery equipment is frequently required for its use. Alternatively, one can reasonably ask is it ethical to charge more for the same device just because it is utilized with a MIS technique? Here, a “probably not” response can be strongly argued.

Richard Fessler

Richard Fessler

It is also important to distinguish between two fundamentally different MIS approaches. On the one hand, there is the “transforaminal endoscopic” approach to MIS, a technique which utilizes the least invasive technique developed so far, but is essentially limited in application to lumbar discectomy. Thus, in this case, a relatively expensive surgical system has only limited utility. A very real argument can be put forth, therefore, that the benefit might not justify the additional cost.

The alternative MIS surgical technique is frequently referred to as “tubular” MIS, a technique which has evolved to the level where nearly all spine surgery can be performed through its use. Furthermore, the additional surgical equipment required to perform these surgeries is relatively minimal, thus up front costs are negligible. Contrary to “additional cost,” abundant data are now revealing surgical procedures using this technique are less costly. Multiple reports comparing MIS to open transforaminal lumbar interbody fusion have reported cost savings using the MIS approach. In our own analysis of surgical correction of adult degenerative scoliosis we have demonstrated a MIS technique can achieve similar results for a cost savings of $120,000 to $240,000 per case in matched cohorts (submitted for publication).

Thus, I would argue it is time to move beyond stereotyped colloquialisms and start examining the accumulating data. Not only are the perceived benefits real, but they can be achieved with less cost.

Richard G. Fessler, MD, PhD, is a professor in the department neurosurgery at Rush University Medical Center in Chicago.
Disclosure: Fessler is a consultant for DePuy Synthes and co-owner of In Q Innovations.