This article is sponsored by Medtronic.
Lateral spine surgery has been an effective procedure for the past decade; now, Oblique Lateral Interbody Fusion (OLIF at L2-L5) gives surgeons lateral access while preserving the psoas and avoiding the iliac crest.
Three spine surgeons discuss the oblique lateral approach.
Q: How have your surgical techniques dealt with the psoas over your career?
Kamal Woods, MD, CFO, Advanced Neurosurgery Associates, Murrieta, Calif.: Early in my neurosurgical training, I did not have a lot of exposure to the retroperitoneal space, with the exception of a handful of retroperitoneal tumors. Later on, I was introduced to the trans-psoas approach, guided by triggered EMG, and immediately realized that this approach was potentially powerful in treating a number of pathologies. However, the trans-psoas approach brought its own setbacks.
Neel Anand, MD, Director of Spine Trauma, Cedars-Sinai Spine Center, Los Angeles: Historically, we always went through the middle of the psoas. The plexus and the nerves are there, so I started to enter more anteriorly a while ago for less psoas disruption. I transitioned to doing more of the oblique procedure around 2010 and realized it's a better way to go.
Q: What do you see as the benefits and disadvantages of the trans-psoas procedure?
Richard Hynes, MD, President, The B.A.C.K. Center, Melbourne, Fla.: The trans-psoas approach is a good one, but has some issues with access to the L4-5 level due to the iliac crest in some patients. If you want to access the L5-S1 space, you have to flip the patient from the side to the supine or prone position to capture it.
For the first time in the history of spine, we are able to reach every disc level from the L5-S1 through the thoracic spine without changing the position of the patient.
KW: Unlike an ALIF or PLIF where the disc space is approached head-on, the initial disc access in OLIF is not orthogonal but oblique. This difference can take some getting used to. Fortunately, it doesn’t take long for a surgeon to makes the mental shift and to appreciate the advantages of the OLIF procedure. It is a beautiful thing to be able to avoid the psoas muscle and the embedded lumbosacral plexus altogether.
NA: You can do a lateral interbody fusion well, but you're still near nerves and the lumbosacral plexus in the psoas. You can avoid that by going obliquely, so it just makes sense.
Q: What lead you to the oblique access offered in the OLIF procedure?
NA: We started seeing neurological issues with the trans-psoas procedure. In 2008, we reported the long-term results for Lateral Lumbar Interbody Fusion (LLIF) patients. We had some issues with patients who underwent the trans-psoas approach and studies from other centers also showed there could be similar complications with around 5 percent of the patients undergoing the procedure.
KW: I would say that there are two main reasons why the OLIF procedure really got my attention. First, OLIF allowed me to access the L5-S1 level in the lateral position thereby obviating the need to reposition the patient just to treat that single level. Also, the oblique access essentially eliminated the challenges sometimes seen at L4-5 pertaining to a high iliac crest and/or an anterior position of the lumbosacral plexus including the femoral nerve.
RH: I wanted a better way to approach the L4-5 and L5-S1 levels after 2006 when a patient experienced a significant femoral nerve injury with transmuscular monitored approach.
Historically we have always done the approach open but anterior to the Psoas. By bringing the MIS tubular approach, Dr. Foley’s method and combining with the historical corridor anterior to the Psoas, we have minimized the risk of lumbar plexus nerve and psoas muscle injury
Q: Do you neuromonitor with OLIF?
RH: When surgeons started doing the transmuscular approaches, they had to do neuromonitoring because they're driving a probe in blindly through the psoas muscle. Patients have increased complaints of transient sensory nerve and Psoas weakness after surgery using the transmuscular methods and the neuromonitoring can only limit some of these complaints and injuries.
Because I am not going through the psoas and the nervous plexus with OLIF, neuromonitoring has become optional. I find it hard to justify this cost and muscular trauma when the goal of access to all of the lumbar disk can be achieved less invasively by simply accessing the disc anterior to the Psoas.
KW: I don't use neuromonitoring for the OLIF procedure, just as I typically don’t use neuromonitoring for ALIFs. The direct visualization during an OLIF is remarkable and allows one to stay away from the psoas muscle and lumbosacral plexus.
NA: I use a neuromonitor with my OLIF cases. I started my spine practice using neuromonitoring and I always have. I do real-time EMG all the time, and it will show you when you're near a nerve. When the neuromonitor is calm, I'm comfortable. When real time EMG is positive or starts to go off, I then do triggered EMG to see how close the nerve is. This has helped me make sure the nerve is not close by and thereby vulnerable to injury. I do think though with the oblique approach as we are not going through the psoas neuromonitoring may be superfluous and not be really needed.
Q: What benefits would you see in avoiding neuromonitoring in lateral procedures?
KW: Lower cost. There is a significant cost associated with using neuromonitoring, especially from a facility standpoint. This cost is partly related to the supplies and personnel needed to perform neuromonitoring, and partly related to the increased time in the operating room from placement and removal of electrodes.
RH: If you don't have to use neuromonitoring, it saves money. In the new era of healthcare, economic savings make a huge impact on care delivery.
Q: How does the use of paralytics effect your lateral procedures?
KW: When doing OLIF vs XLIF and DLIF I’m not doing triggered EMG, so we can paralyze the patient. This relaxes the muscles of the abdominal wall and, therefore, facilitates access. Also, the psoas muscle itself is relaxed, and can be more easily mobilized posteriorly, if necessary, to create a wider window between the aorta and the psoas muscle.
RH: We gave up the use of muscle paralytics with the advent of XLIF, DLIF and other transmuscular approaches. In our practice, relaxed muscle gives the surgeon more fidelity in dissection and less trauma to the patients muscle.
Q: What differences have you experienced with the position of the patient for OLIF versus XLIF and DLIF?
KW: OLIF does not require breaking the table. This is especially relevant as there is increasing consensus that breaking the table may lead to postoperative complications, including femoral nerve injury. Furthermore, OLIF uses a more anterior incision than typical trans-psoas approaches. The surgeon is able to stand upright with the arms and forearms relaxed. The neck is not excessively flexed, and the eyes can readily gaze down the oblique corridor that is created.
RH: When you work with the transmuscular approach, you are working and viewing parallel to the epidural muscle. But with OLIF, because of the angle of the approach, you get a view of the trajectory of the epidural space. We can remove ventral osteophytes and disc herniations to combine the direct and the indirect decompression benefits. Direct view of the ALL anterior longitudinal ligament allows either preservation or release in a safe manner.
NA: There is no difference in my practice. We used to make a big effort to open the space between the iliac crest and psoas, but we stopped doing that around 2007 with the less invasive approaches.
Q: How have you resolved the challenges of the iliac crest and the lateral approach?
KW: With the OLIF procedure at L2-L5, the position of the iliac crest has become for all practical purposes irrelevant. Even when the crest is high, the anterior location of the incision and the oblique trajectory both allow the surgeon to access the spine without limitation.
RH: I've had great success with OLIF at L2-L5 for degenerative scoliosis patients, where I can perform a two-level OLIF with release of anterior longitudinal ligament combined with a PCO, Posterior Column Osteotomy, and obtain the equivalent correction of a single-level PSO, Pedicle Subtraction Osteotomy. This may open up an opportunity for more community based surgeons to perform the correction of the sagittal plate for moderate deformity while preserving PSO for more advanced cases at centers that focus on complex deformity.
NA: If you just go a little anterior and oblique, you clear the crest immediately. That has worked efficiently for me at the L4-5. Even with the most difficult patients with adult degenerative scoliosis, we have had success.
Q: What surgeon benefits have you experienced using oblique access versus traditional access?
RH: The surgeon operates hunched over the patient with the transmuscular approach, looking down with a bent neck and back. That's a poor way to operate (the surgeon has a poor sagittal plane while operating), especially for young surgeons. With the OLIF procedure, the surgeon can feel more relaxed with a more normal posture during surgery. You don't have to bend your head, and you don't have to move the fluoroscopy. It's subtle, but it's nice when you can stand straight and the fluoroscopy image is looking right at you.
For me, I don't have to do this approach for 35 more years, but if I were a younger surgeon, I wouldn't do the current transmuscular lateral approach to save myself physiologically.
KW: The key thing is happy patients. Happy patients make happy surgeons! Before OLIF, my lumbar fusion patients spent two or three days in the hospital, but my OLIF patients want to go home the day after surgery.
NA: There is less disruption of the lumbosacral plexus, and the oblique approach allows you to avoid neurological structures in the psoas.
Indications
The CLYDESDALE® Spinal System is designed to be used with autogenous bone graft to facilitate interbody fusion and is intended for use with supplemental fixation systems cleared for use in the lumbar spine. The CLYDESDALE® Spinal System is used for patients diagnosed with Degenerative Disc Disease (DDD) at one or two contiguous levels from L2 to S1. DDD patients may also have up to Grade 1 Spondylolisthesis or
retrolisthesis at the involved levels. DDD is defined as discogenic back pain with degeneration of the disc confirmed by history and radiographic studies. Additionally, the CLYDESDALE® Spinal System can be used to provide anterior column support in patients diagnosed with degenerative scoliosis as an adjunct to pedicle screw fixation. These patients should be skeletally mature and have had six months of nonoperative treatment. These implants may be implanted via a minimally invasive lateral approach.
Risks Include
Implant migration; breakage of the device(s); loss of proper spinal curvature, correction, height, and/or reduction; loss of neurological function, appearance of radiculopathy, dural tears, and/or development of pain; neurovascular compromise.
Contact Customer Service or your Sales Representative, or visit http://manuals.medtronic.com for the most up-to-date revision of the package insert for the complete list of indications, warnings, precautions, and other important medical information. This therapy is not for everyone. Please consult your physician. A prescription is required. For further information, please go to www.medtronic.com.
The CLYDESDALE® Spinal System incorporates the technology of Gary K. Michelson, MD.