Surgeons well-versed in the thoracolumbar spine's anatomy can yield superior patient outcomes through a lateral approach, such as reduced infection rates and minimal blood loss.
Choll Kim, MD, of the Spine Institute of Diego, and Robert Eastlack, MD, a spine surgeon in San Diego within Scripps Clinic's division of orthopedic surgery, dive into their approach and the many components involved in successfully employing lateral spine surgery.
Question: Which are the main surgical procedures that you undertake using a lateral approach, and how do you decide which are the most suitable patients and cases?
Dr. Robert Eastlack: I use the lateral approach most often for reconstruction/arthrodesis in the lumbar spine above the fifth lumbar vertebra. This is most often done for instability, such as spondylolisthesis and occasionally for more complex deformities.
Dr. Choll Kim: The lateral lumbar interbody fusion procedure is particularly well-suited to treat patients with stenosis due to degenerative scoliosis. With the increasing age of the U.S. population, the population of patients with stenosis due to degenerative scoliosis is rapidly growing.
Q: How long have you been doing lateral spine surgery and what were the key challenges as you learned the procedures?
RE: I have been using this approach since 2004. The biggest challenge in performing the technique safely is being familiar with the anatomy. The lateral approach is a unique pathway to access the thoracolumbar spine, but the anatomy involved in the surgical approach was not historically well-understood. Greater awareness of this anatomy and well-designed instrumentation systems now allow for tremendous utility and safety in lateral spine surgery.
CK: I have been doing lateral spine surgery for about 12 years. When we originally did the procedure, we did it completely percutaneously through two incisions. In the more contemporary method, spine surgeons make one incision. This was a challenge we had to overcome because spine surgeons generally don't like performing blind surgery.
The second challenge we overcame was related to good imaging. It took a lot of positioning and understanding of the anatomy of the lumbar spine and nerves to go through the psoas muscle. When we get the direct vision, we can be much gentler with that muscle and traumatize it less. It took between about 20 to 30 cases to overcome these challenges.
Q: What benefits do you see from your lateral approach surgeries?
CK: The LLIF approach is minimally invasive so it provides significant improvements in pain, blood loss and infection in this normally frail population of patients. Furthermore, the large size of the implant, together with its position spanning the disc space, provides better implant stability. This is very important in older patients with osteoporotic bone. The LLIF implant is very stable and resistant to subsidence. The LLIF procedure is a cornerstone of my practice.
RE: The main benefits are superior disc removal and endplate coverage, less subsidence than posterior interbody cages, greater fusion rates than posterior interbody approaches with equivalent biologics, greater improvement and maintenance of segmental alignment. [Other benefits include] less morbidity than traditional anterior lumbar interbody approaches, greater stability than posterior interbody cages, less subsidence than posterior interbody devices and offering the potential for indirect decompression of neural elements.
Q: How do you decide whether to stage the lateral and posterior parts of the surgery over more than one day and when to carry them out in a single surgical case?
RE: For the majority of one-level to three-level reconstructions, the procedure can be accomplished in one day. Staging of the procedure is more commonly considered when utilizing the lateral approach as part of a larger deformity operation, in which case the posterior reconstruction is done at a later time/date, and interim standing radiographs can be employed to determine what posterior techniques can be optimally employed to achieve the radiographic goals.
CK: I have some general guidelines [for doing the surgery over the course of more than one day]. These include if the patient is over 65 years old, has three levels or more or other co-morbidities such as diabetes or a history of heart disease. I do it in more than one day for the more complicated and extensive procedures where the patient is more frail. This prolongs the recovery for the patient but is generally safer when it is spread over two days. There is a lot of gray area in that distinction. No one has sat down and figured out the best time to split it into one or two days. We have examples of the two extremes — healthy, level-one or level-two patients and then patients with three levels or more. Besides that, the exact switch point is not clear and we do it on a case-by-case basis.
Q: In terms of patient positioning, what are the key elements and challenges?
CK: The LLIF procedure requires careful patient positioning and optimal intra-operative imaging. The patient has to be secure in true lateral position relative to the floor. If there is rotatory deformity, then the operating table must rotate to accommodate this deformity, whilst still allowing for clear intraoperative radiographic imaging. The major challenge occurs when the C-arm is unduly encumbered by the break in the bed or pedestal of the bed. Therefore, it is imperative that the patient is carefully positioned on the appropriate operating table.
RE: The initial challenge was training the operating room team to adjust to a unique process. The success of the operation depends largely on the precision of initial patient positioning and fluoroscopy preparation. The first key to patient positioning is maintaining hip and knee flexion of both lower extremities, and minimizing any table flexion, so that the psoas and lumbar plexus are kept in relatively relaxed condition. Another key aspect of positioning is placing the patient so that the segmental level is addressed for reconstruction and is orthogonally positioned relative to the fluoroscopy beam that has been set up for anteroposterior and lateral views. This minimizes the potential error in reproducing proper view with imaging and increases efficiency for the technician running the fluoroscopy unit.
Q: Why and when would you reposition the patient during surgery?
RE: The most common reason for repositioning a patient is the need to address more than one level, such as with correction of a deformity, in which there is rotation of the spinal segments. This requires resetting the patient via table control in both rotation and the Trendelenburg [position] to bring the next spinal segment into an orthogonal position for the fluoroscopy beam. The other more obvious need to reposition a patient occurs after the lateral approach is completed, at which point prone positioning is accomplished in order to perform the posterior reconstruction.
There is the option in some cases of doing a single position lateral and posterior reconstruction. In this case, both the lateral and posterior surgery is done with the patient in the lateral decubitus position, and thus avoiding the transfer to another operative table and the requisite repeat draping of the patient.
CK: In healthy patients, we often perform the LLIF procedure and the posterior procedure on the same day. This has been a cumbersome process to placing the patient from the lateral decubitus position to the prone position.
Q: What are the potential hazards of patient repositioning and what are the human factors involved, specifically as it relates to the OR staff?
CK: In my experience, the repositioning process is cumbersome and labor intensive. Currently, we have about five OR staff members involved in moving the patient to a gurney, the switching out the table for the prone frame. At each step, there is lifting involved, which places staff at increased risk of injury, not to mention the risk of contamination of the sterile field.
RE: The primary hazard of repositioning the patient while still in the lateral decubitus position is ensuring that the desired vertebral rotation to neutral position has been accomplished to ensure orthogonal cage delivery. The patient must be secured to the table with strong tape at the trunk, pelvis and lower extremities, in order to safely accommodate rotating the table into the desired position. Prone repositioning does not carry any unusual risks, other than those inherent in putting any patient into a prone position.
Q: How important are OR logistics in creating a true center of excellence for minimally invasive techniques?
CK: A true center of excellence is in constant improvement. We have identified the repositioning step to be a significant weakness in our minimally invasive program, which is why we have been working on developing a simple and efficient strategy that allows the patient to be rolled from the lateral position directly into the prone position. The new Allen® Advance Table L2P™ Platform represents our ongoing efforts to optimize this aspect of minimally invasive surgery.
RE: It is quite critical that the OR team is experienced and well-trained in preparing for and utilizing this technique. The efficiency with which the patient is positioned, and with which the surgery is performed, both depend largely on the skill and experience of the entire operative team.
This article is sponsored by Allen Medical. Allen Medical is an industry leader in patient positioning and surgical site access. Our passion is improving patient outcomes and caregiver safety while enhancing our customers’ efficiency. We strive to provide innovative solutions to address our customers’ most pressing needs. By immersing ourselves in our customers’ world, we can better address these needs and the daily challenges of their environment.