Tender et al. Journal of Medical Case Reports 2011, 5:454 http://www.jmedicalcasereports.com/content/5/1/454 Page 5 of 6 Figure 6 Computed tomographic coronal (left) and sagittal (right) images demonstrate successful fusion at one-year follow-up. transforaminal approach followed by percutaneous pedi- cle screw reduction of spondylolisthesis has been described along with a report of acceptable clinical and radiographic results [4]. While this approach provides direct unilateral decompression of the neural foramen, access to the disc space is limited because of the steep angle and narrow working corridor inherent to spondy- lolisthesis cases. Severely collapsed disc spaces are fre- quently encountered in these patients, adding considerable technical challenges to achieving adequate interbody distraction through a minimally invasive approach. In contrast, percutaneous reduction of spondylolisthesis by using bilateral pedicle screws offers several potential advantages. Reduction may be accomplished using simul- taneous bilateral screw fixation, thus decreasing the risk of L5 pedicle screw pull-out and limiting the risk of endplate violation inherent to an initial interbody approach to reduction. Another major advantage of this technique is offered by the axial presacral approach, which allows ante- rior access to the L5-S1 (or L4-S1) discs in the prone posi- tion. Once the spondylolisthesis reduction is achieved with pedicle screws, placement of the anterior axial rod becomes routine and also offers the option of further indirect foraminal decompression. As before, this com- bined technique is possible only because both the percuta- neous pedicle screw reduction and the presacral approach can be performed in the prone position. One major concern with this surgical technique is the potential for the pedicle screw system to fail in reducing the spondylolisthesis. In this situation, the pedicle screws on one side may be temporarily removed and a minimally invasive transforaminal approach may be employed on that side through the same incision to pro- vide the discectomy and interbody graft placement as previously described. The AxiaLIF System is not intended to treat severe scoliosis, severe spondylolisthesis (grade 3 or 4), tumor, or trauma. Contraindications for use include coagulopathy, bowel disease, pregnancy, and sacral agenesis. Use of the AxiaLIF System is limited to ante- rior fusion of the lumbar spine at L5-S1 (2-LEVEL Sys- tem for L4-S1) in conjunction with legally marketed posterior fixation systems. The AxiaLIF System should not be used with facet screws when spinal stenosis correction requires removal of significant portions of the lamina or any portion of the facets. The 2-LEVEL System is additionally contraindicated for patients with vertebral compression fractures or any other condition in which the mechanical integrity of the vertebral body is compromised. Preoperative imaging should be thoroughly evalu- ated with emphasis on perirectal fat pad thickness, identification of the rectum/sacrum interface, aber- rant vasculature, and anticipated trajectory. Thus, relative contraindications for the presacral approach include insufficient presacral fat pad, previously explored presacral space, large vessels crossing the presacral space, and anatomic abnormalities that pre- clude placement of an axial rod through the lower lumbar segments. Conclusions This case series describes an alternative and viable approach for the treatment of lumbosacral spondylo- listhesis. Spondylolisthesis reduction using a percuta- neous pedicle screw system allows the placement of an anterior axial rod, which in turn can further distract the interspace and indirectly decompress the neuroforamina. This minimally invasive approach was used safely in three patients. A larger study with long-term follow-up is needed to validate this procedure.