Fluoroscopy is used to confirm proper positioning of the interbody cage. After removal of the working channel, a jamshidi needle is localized to the unilateral pedicle either above or below the discectomy level, and positioning is checked using fluoroscopic imaging. A K-wire driver is used to insert a guide certainly wire into the superficial portion of the pedicle. A SEXTANT percutaneous screw system (Medtronic Inc; Memphis, TN) is used to pass a cannulated pedicle screw over the K-wire and into the pedicle under fluoroscopic guidance. This is repeated at all desired pedicles on either side. The SEXTANT holding sleeves are mated, the percutaneous rod holder and guide are attached, and a small skin incision is made to pass the rod percutaneously through the screw head.

After correct positioning of the rod is confirmed with fluoroscopy, the screw head is tightened, the rod holder is released, and the holding sleeve is removed. Skin closure is accomplished in the standard fashion. For a full detailed description see Lawton et al. [18], see Figures Figures11 and and22 for illustrative cases from patients treated with the MI-TLIF procedure. Figure 1 (a) Preoperative lateral MR image of a 72 y/o female patient with back and left leg pain and L4/L5 spondylolisthesis; (b) post-operative lateral MR image from a patient who underwent an MI-TLIF for spondylolisthesis at L4/L5. Figure 2 (a) Preoperative lateral MR image of a 66 y/o female with L4/L5 and L5/S1 spondylolisthesis and neuroforaminal stenosis; (b) Post-operative lateral MR image from a patient who underwent an MI-TLIF for spondylolisthesis at L4/L5, L5/S1.

4. Review of the Literature As noted, our review included 14 articles. Follow-up times ranged across all articles from 6 months to 42 months. The mean follow-up was 20 months, with a mean patient cohort of 52 patients. Within seven of the articles that directly compared outcomes of open TLIF with MI-TLIF, mean duration of MI-TLIF surgery was 220 minutes, compared to 218 minutes for its open counterpart. Furthermore, blood loss was found to be on average 282mL in MI-TLIF cases, while open TLIF resulted in 693mL of blood loss. The length of stay for MI-TLIF was found to be 5.6 days, while open TLIF had patients in the hospital for an average of 8.1 days (see Table 2). Table 2 Comparative studies basic data. 4.1. Complications Though the literature displayed possible benefit of MI-TLIF relative to its open counterpart, both procedures are associated with possible complications. Major sources of complications AV-951 shared by MI-TLIF and Open TLIF are allograft malposition, pedicle screw malposition, and infection [8]. Some minor complications found in both open and MI studies were hematoma, anemia, and cerebrospinal fluid leakage [8].