Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters

Abstract

BACKGROUND CONTEXT Sagittal alignment is becoming an increasingly important consideration in minimally invasive spine surgery. Single level minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) can have immediate impact on segmental and regional sagittal parameters. PURPOSE The purpose of this study was to compare immediate restoration of segmental (SL) and regional lordosis (RL) after single level MIS TLIF using an expandable or static interbody cage. STUDY DESIGN/SETTING All patients underwent single level MIS TLIF using tubular retractor and bilateral pedicle screw fixation with interbody cage. Measurements of preoperative RL and SL were made and compared with post operative values. Patients were divided into 3 groups based on their preoperative SL: low lordosis ( 25°). Mann Whitney u test was used to determine statistical significance of results PATIENT SAMPLE Patients who underwent single level MIS TLIF. OUTCOME MEASURES Segmental and regional lordosis after single level MIS TLIF using an expandable or static interbody cage METHODS A retrospective review of prospectively collected data on patient undergoing single level MIS TLIF using expandable or static interbody cages was performed. All patients underwent single level MIS TLIF using tubular retractor and bilateral pedicle screw fixation with interbody cage. Measurements of preoperative RL and SL were made and compared with post operative values. Patients were divided into 3 groups based on their preoperative SL: low lordosis ( 25°). Mann Whitney u test was used to determine statistical significance of results. RESULTS A total of 114 patients were included with 57 patients in the expandable cohort and 53 in the static cohort. The expandable cohort had an average age of 64 (37–86) and 34 females. The static cohort had an average age of 58 (24–80) and 27 females. In the expandable cage cohort, patients who had low lordosis preoperatively had a statistically significant increase in postoperative SL (p CONCLUSIONS This study compares the immediate impact of MIS TLIF using expandable or static cages on segmental lordosis of the lumbar spine. Our findings suggest that while cage type does not impact postoperative lordosis, a patient's preoperative lordosis can. Specifically, those patients with low lordosis preoperatively (>15°) have the highest likelihood of achieving statistically significant improvement in segmental lordosis while those with moderate (15–25°) or high (>25°) lordosis preoperatively may experience no change or even a loss of lordosis postoperatively.