A comparison of modern-era anterior lumbar interbody fusion and minimally invasive transforaminal lumbar interbody fusion at the lumbosacral junction.

OBJECTIVE: Interbody fusion is the primary method for achieving arthrodesis across the lumbosacral junction in the setting of degenerative pathologies, such as spondylosis and spondylolisthesis. Two common techniques are anterior lumbar interbody fusion (ALIF) and posterior transforaminal lumbar interbody fusion (TLIF). In recent years, interbody design and technology have advanced, and most earlier studies comparing ALIF and TLIF did not specifically assess the lumbosacral junction. This study compared changes in radiographic and clinical parameters between patients undergoing modern-era single-level ALIF and minimally invasive surgery (MIS) TLIF at L5-S1. METHODS: Consecutive patients who underwent single-segment L5-S1 ALIF or MIS TLIF performed by the senior authors over a 6-year interval (January 1, 2016-November 30, 2021) were retrospectively reviewed. Upright radiographs were used to determine pre- and postoperative lumbar lordosis, segmental lordosis, disc angle, and neuroforaminal height. Improvements in patient-reported outcome scores (Oswestry Disability Index and SF-36) were also compared. RESULTS: Overall, 108 patients (58 [54%] men, 50 [46%] women; mean [SD] age 57.6 [13.5] years) were included in the study. ALIF was performed in 49 patients, and TLIF was performed in 59 patients. The most common treatment indications were spondylolisthesis (50%, 54/108) and spondylosis (46%, 50/108). The cohorts did not differ in terms of intraoperative (p > 0.99) or postoperative (p = 0.73) complication rates. The mean (SD) hospital length of stay was significantly shorter for patients undergoing TLIF than ALIF (1.3 [0.6] days vs 2.0 [1.4] days, p < 0.001). Both techniques significantly improved L5-S1 segmental lordosis, disc angle, and neuroforaminal height (p ≤ 0.008). ALIF versus TLIF significantly increased mean [SD] segmental lordosis (12.5° [7.3°] vs 2.0° [5.7°], p < 0.001), disc angle (14.8° [5.5°] vs 3.0° [6.1°], p < 0.001), and neuroforaminal height (4.5 [4.6] mm vs 2.4 [3.0] mm, p = 0.008). Improvements in patient-reported outcome parameters and reoperation rates were similar between cohorts. CONCLUSIONS: When treating patients at a single segment across the lumbosacral junction, ALIF resulted in significantly greater increases in segmental lordosis, L5-S1 disc angle, and neuroforaminal height compared with MIS TLIF. Improvements in clinical parameters and reoperation rates were similar between the 2 techniques.

Technique for Validation of Intraoperative Navigation in Minimally Invasive Spine Surgery.

BACKGROUND: Intraoperative 3-dimensional navigation is an enabling technology that has quickly become a commonplace in minimally invasive spine surgery (MISS). It provides a useful adjunct for percutaneous pedicle screw fixation. Although navigation is associated with many benefits, including improvement in overall screw accuracy, navigation errors can lead to misplaced instrumentation and potential complications or revision surgery. It is difficult to confirm navigation accuracy without a distant reference point. OBJECTIVE: To describe a simple technique for validating navigation accuracy in the operating room during MISS. METHODS: The operating room is set up in a standard fashion for MISS with intraoperative cross-sectional imaging available. A 16-gauge needle is placed within the bone of the spinous process before intraoperative cross-sectional imaging. The entry level is chosen such that the space between the reference array and the needle encompasses the surgical construct. Before placing each pedicle screw, accuracy is verified by placing the navigation probe over the needle. RESULTS: This technique has identified navigation inaccuracy and led to repeat cross-sectional imaging. No screws have been misplaced in the senior author's cases since adopting this technique, and there have been no complications attributable to the technique. CONCLUSION: Navigation inaccuracy is an inherent risk in MISS, but the described technique may mitigate this risk by providing a stable reference point.