Tender et al. Journal of Medical Case Reports 2011, 5:454 http://www.jmedicalcasereports.com/content/5/1/454 Case presentation Three patients who underwent this operative procedure were evaluated retrospectively. The operations were per- formed between September 2009 and February 2010 at the Louisiana State University academic hospital (New Orleans, LA, USA). Preoperative imaging included lum- bosacral magnetic resonance imaging (MRI) to assess the diseased segments (Figure 1) and to evaluate poten- tial contraindications for the presacral approach (for example, hooked or flat sacrum, large crossing vessels, or minimal presacral fat). Flexion-extension lateral X- rays were used to evaluate spondylolisthesis mobility. The patients were selected on the basis of imaging evi- dence of low-grade spondylolisthesis and axial pain with concomitant lumbar radiculopathy [6]. Preoperative lumbar MRI demonstrated grade 2 spondylolisthesis at L5-S1 in all patients and an associated grade 1 spondy- lolisthesis at L4-L5 in one case. A standardized surgical protocol was used for each case. Each patient was placed prone on a translucent operative table on a Wilson frame (to allow the initial exploration of the presacral space) with ample space for the C-arms underneath the table at the level of the lum- bar and sacral spine. Biplanar fluoroscopy was used throughout each case. The procedure began with the percutaneous pedicle screw placement as previously described [4]. Briefly, two 2 cm incisions were made, and each was about 4 cm on either side of the midline and centered over the disc space of interest. Next, a Jamshidi needle was docked at the junction between the transverse process and lateral facet and then advanced in a lateral-to-medial direction. When the tip of the needle reached the base of the pedicle on the lateral image, the anteroposterior image showed the tip within the oval shape of the pedicle but not past its medial border. Neurostimulation of the Page 2 of 6 needle was performed at this time to confirm that the wall of the pedicle was not breached, and this was fol- lowed by a K-wire, tap, and pedicle screw. This proce- dure was repeated for the other pedicles; the only difference was that a Ferguson modification of the ante- roposterior fluoroscopic view was used for the S1 pedi- cle cannulation. We used the CD Horizon Sextant system (Medtronic Sofamor Danek, Memphis, TN, USA) for percutaneous reduction of lumbar spondylolisthesis as previously described [4]. For the patient with L4-5 and L5-S1 disease, the screws at L5 and S1 were initially placed and the tra- jectory for the L4 pedicle screw was determined to accom- modate the percutaneously inserted rod (Figure 2). The reduction screw extender allowed up to 2 cm of translation of the listhesed vertebral body relative to the extender body, hence the limitation of this technique to spondylolisthesis cases of not more than grade 2. Long screws with good purchase were used for the L5 pedicle since high pull-out strength is essential for successful reduction. Once spondylolisthesis reduction was achieved, the screw caps were attached and temporarily locked in place. Attention was given to the presacral approach. The trajectory of the axial rod was planned on sagittal MRI images before the operation. With the spondylo- listhesis at least partially reduced, this anterior trajectory was deemed feasible in all cases on the basis of preo- perative imaging analysis. Therefore, a 2 cm paracoccy- geal skin incision was made and the presacral approach was performed to place the anterior axial rod as pre- viously described [7]. Specifically, the entry point was selected under fluoroscopic guidance close to the S1-2 junction (on the lateral images) and close to the midline (on the anteroposterior images) so that the extension of a straight line from the entry point would cross the cen- ter of the L5-S1 disc (for the single-level cases) or the Figure 1 Lumbar midline sagittal T2-weighted magnetic resonance images. Grade 2 L5-S1 spondylolisthesis (case 1, left) and combined grade 2 L5-S1 anterolisthesis and grade 1 L4-5 retrolisthesis (case 3, right) are shown. Figure 2 Intraoperative lateral (left) and anteroposterior (right) fluoroscopic images depict Jamshidi needle insertion into the left L4 pedicle (case 3). When the tip of the needle reaches the base of the pedicle on the lateral image, it remains within the pedicle contour on the anteroposterior image.