Direct Lateral Interbody Fusion: Standard and Anterior Column Realignment
Mathew Cyriac
Keith Michael
Illustrative Case
A 70-year-old female with bilateral buttock and leg pain worse with standing/walking and significant relief with rest (Figures 25-1 and 25-2).
 Figure 25-1 ▪ A-D, Anteroposterior and lateral films showing flatback and significant positive sagittal balance. |
 Figure 25-1 ▪ (continued) |
 Figure 25-2 ▪ A, B, Sagittal and axial MRI showing severe L3-4 central and lateral recess stenosis. On the axial, the psoas sits on the lateral aspects of the disk without ventral displacement. Note that the aorta and inferior vena cava are ventral to the disk; when draped over the lateral aspect of the disk space, release of the far annulus must be performed cautiously. |
Radiologic Assessment
Look at anteroposterior (AP) and lateral radiographs to determine accessibility of each disk level relative to the iliac crest and ribs (Figure 25-3).
The approach side is determined by the orientation of the L4-5 disk relative to the iliac crest. This is especially important in scoliosis cases (Figure 25-3B).
Figure 25-3 ▪ A, Lateral lumbar x-ray with ribs and iliac crest superimposed to determine which levels are accessible with a lateral approach. The three yellow lines indicate varying heights of the iliac crest relative to the L4-5 disk. The caudal yellow line allows direct orthogonal access, whereas the cranial yellow line may require use of angled instruments to access the L4-5 disk space. B, The approach side is often determined by using an anteroposterior lumbar x-ray to evaluate the trajectory of the L4-5 disk. In this case, a left-sided approach would be difficult at L4-5 because of angulation of the disk relative to the iliac crest. (Reprinted with permission from Rhee JM et al. (ed.) Operative Techniques in Spine Surgery, 2nd ed., Philadelphia, PA: Wolters Kluwer; 2016.)
Look at axial MRI to determine proximity of inferior vena cava (IVC) and aorta to vertebral body (Figure 25-2). In the setting of scoliosis, sometimes the vessels can be draped over the lateral side, which means contralateral release of annulus with the Cobb should be done with extreme caution.
Look at the shape of the psoas on the axial cut of the disk space. Ventral displacement or “Mickey Mouse” ears, especially at L4-5, indicates that the lumbar plexus is anterior, resulting in a higher likelihood of encountering it during the approach (Figure 25-4).
 Figure 25-4 ▪ Axial MRI comparing a normal psoas to transitional psoas with “Mickey Mouse” ears. |
Special Equipment
Regular OR table reversed with the headpiece attached to the foot of the bed
Free-running and triggered electromyography (EMG) neuromonitoring
Place the leads thumb width apart in the appropriate muscles per company-specific neuromonitoring protocol.
Bar for retractor will be placed on anterior aspect of patient distal to the break in the bed.
Place distal enough so the bar/rod will not be in the way of the C-arm. Make sure tape is not placed right at the break in the bed or it will become loose when the bed is flexed.
Room Setup
Set up the room so that the fluoroscopy monitor can be easily seen from the operative position.
The scrub tech should be on the back side of the patient with the table positioned orthogonally at the foot of the bed.
The C-arm approaches the table in line with the disk space so that when flipped to an AP view it is already in line with the endplate (Figure 25-5).
 Figure 25-5 ▪ Reverse regular OR table position so foot of base will be out of the C-arm path. Head piece is attached to the foot of the bed (opposite to foot of base). The patient’s iliac crest lies around the break in the bed. Do not place any tape directly over the iliac crest/break site. |
Positioning
Ensure that OR table is perpendicular to room landmarks.
Call for C-arm as soon as patient is induced.
Insert neuromonitoring needles for triggered and free-running EMGs with patient in supine position.
Position patient lateral with folded sheet bump under contralateral greater trochanter.
Usual approach is with the left side up
Iliac crest should be positioned 3 inches proximal to the break of the table
Bring patient slightly posterior on table for ease of surgical access by the surgeon, but not all the way to the edge so that longitudinal rail is not in the way of the C-arm lateral view.
Two rounds of tape (3 in) around table at level of greater trochanter
Two rounds of tape around the chest, under the axilla (Figure 25-6)
Figure 25-6 ▪ Tape around the chest and greater trochanter.
Two tape rolls, simultaneously starting from greater troch to the ipsi- and contralateral sides of the bed to tip the pelvis down. This method of taping requires less break of the table but still allows for tilting the pelvis distally (Figure 25-7).
Figure 25-7 ▪ Two rolls of tape are placed near the greater trochanter and pulled to each side of the bed to pull the iliac crest down.
Lower the foot of the bed down to tilt the pelvis. Generally do not need to bring the head down.
Remember that the foot of the bed is really the “head” on the control because the bed is reversed.
Ensure clamp is on bedrail for placement of retractor arm holder.
Ensure arm board for contralateral arm is at 90° or greater from the table so as not to prevent C-arm cross-table AP. All wires should be taped to bed so as not in the way of the C-arm at the operative site (Figure 25-8).
 Figure 25-8 ▪ Final patient position after taping with the C-arm before draping to ensure adequate views can be obtained. |
Localization
Prior to prepping, adjust position of bed (and potentially patient) to ensure that perfect AP and then lateral images can be obtained with the C-arm in the 90° and 180° positions (Figure 25-9).
Adjust rotation of bed (not C-arm) to obtain perfect AP.
Figure 25-9 ▪ A, Perfect anteroposterior view showing the spinous process centered in between the pedicles and a clear view of the pedicles. B, Lateral x-ray showing clear endplates.
Perfect AP: at the level being worked on, the spinous process (SP) should be in the middle of the two pedicles.
Depending on the lordosis, the C-arm will need to be wigwagged to match disk angle because of lordosis. This is the only time the C-arm is adjusted.
Next obtain orthogonal lateral view and then adjust Trendelenburg as needed to get a perfect lateral.
Perfect lateral: endplates at the level being worked are perfectly aligned/overlapped.
After draping, use cruciate localizer or K-wire under lateral fluoroscopy to draw a line along the disk space (Figure 25-10A).Related posts:
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