Study Design. A retrospective cohort study at a single institution. Objective. The aim of this study was to analyze the perioperative and postoperative outcomes of patients who underwent open transforaminal lumbar interbody fusion (O-TLIF) and bilateral minimally invasive surgery (MIS) Wiltse approach TLIF (Wil-TLIF). Summary of Background Data. Several studies have compared open TLIF to MIS TLIF; however, comparing the techniques using a large cohort of one-level TLIFs has not been fully explored. Methods. We reviewed the charts of patients undergoing a single-level primary posterior lumbar interbody fusion between 2012 and 2017. The cases were categorized as Open TLIF (traditional midline exposure including lateral exposure of transverse processes) or bilateral paramedian Wiltse TLIF approach. Differences between groups were assessed by t tests. Results. Two hundred twenty-seven patients underwent one-level primary TLIF (116 O-TLIF, 111 Wil-TLIF). There was no difference in age, gender, American Society of Anesthesiologists (ASA), or body mass index (BMI) between groups. Wil-TLIF had the lowest estimated blood loss (EBL; 197 vs. 499 mL O-TLIF, P ≤ 0.001), length of stay (LOS; 2.7 vs. 3.6 days O-TLIF, P ≤ 0.001), overall complication rate (12% vs. 24% O-TLIF, P = 0.015), minor complication rate (7% vs. 16% O-TLIF, P = 0.049), and 90-day readmission rate (1% vs. 8% O-TLIF, P = 0.012). Wil-TLIF was associated with the higher fluoroscopy time (83 vs. 24 seconds O-TLIF, P ≤ 0.001). There was not a significant difference in operative time, intraoperative or neurological complications, extubation time, reoperation rate, or infection rate. Conclusion. In comparing Wiltse MIS TLIF to Open TLIF, the minimally invasive paramedian Wiltse approach demonstrated the lowest EBL, LOS, readmission rates, and complications, but longer fluoroscopy times when compared with the traditional open approach. Level of Evidence: 3

2.

Anterior removal of a lumbar total disc replacement implant is often a very technically demanding procedure. The anterior retroperitoneal anatomy is prone to scarring, limiting remobilization and making a direct anterior exposure above the L5-S1 level difficult if not impossible to achieve safely. Anterolateral approach strategies can be more safely achieved at L4-L5 and above, but may require vertebral osteotomy in order to remove a keeled prosthesis. Successful conversion to a fusion with implant removal can be achieved, even when osteotomy is needed for implant removal. This Grand Rounds case presentation involves an unusual late retroperitoneal abscess following two-level TDR with direct extension to one of the implants, and the subsequent nonoperative and operative management. Removal of a well-fixed keeled implant at the L4-L5 level following nonoperative treatment of a surrounding retroperitoneal abscess and conversion to fusion represents close to, if not a 'worst-case' scenario for revision TDR. However, with proper preoperative planning and surgical experience, a safe and successful procedure can be the end result.

Our results suggest that a PSF using newer-generation multisegmented hook-screw and rod systems can be successful with allograft and/or local bonegraft without the use of supplemental autogenous bone graft (from the iliac crest or ribs) in patients with AIS.