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Study Design Systematic Review. Objective To collect and group definitions of segmental instability, reported in surgical studies of patients with lumbar spinal stenosis (LSS) and/or lumbar degenerative spondylolisthesis (LDS). To report the frequencies of these definitions. To report on imaging measurement thresholds for instability in patients and compare these to those reported in biomechanical studies and studies of spine healthy individuals.To report on studies that include a reliability study. Methods This review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Studies eligible for inclusion were clinical and biomechanical studies on adult patients with LDS and/or LSS who underwent surgical treatment and had data on diagnostic imaging. A systematic literature search was conducted in relevant literature databases. Full text screening inclusion criteria was definition of segmental instability or any synonym. Two reviewers independently screened articles in a two-step process. Data synthesis presented by tabulate form and narrative synthesis. Results We included 118 studies for data extraction, 69% were surgical studies with decompression or fusion as interventions, 31% non-interventional studies. Grouping the definitions of segmental instability according similarities showed that 24% defined instability by dynamic sagittal translation, 26% dynamic translation and dynamic angulation, 8% used a narrative definition. Comparison showed that non-interventional studies with a healthy population more often had a narrative definition. Conclusion Despite a reputation of non-consensus, segmental instability in the degenerative lumbar spine can radiologically be defined as > 3 mm dynamic sagittal translation.

OBJECTIVEThe purpose of this study was to investigate the effect of tranexamic acid (TXA) compared to placebo in low-risk adult patients undergoing elective minor lumbar spine surgery—specifically with respect to operative time, estimated blood loss, and complications. Studies have shown that TXA reduces blood loss during major spine surgery. There have been no previous studies on the effect of TXA in minor lumbar spine surgery in which these variables have been evaluated.METHODSThe authors enrolled patients with ASA grades 1 to 2 scheduled to undergo lumbar decompressive surgery at Middelfart Hospital into a double-blind, randomized, placebo-controlled, parallel-group study. Patients with thromboembolic disease, coagulopathy, hypersensitivity to TXA, or a history of convulsion were excluded. Patients were randomly assigned, in blocks of 10, to one of 2 groups, TXA or placebo. Anticoagulation therapy was discontinued 2–7 days preoperatively. Prior to the incision, patients received either a bolus of TXA (10 mg/kg) or an equivalent volume of saline solution (placebo). Independent t-tests were used to compare differences between the 2 groups, with statistical significance set at p < 0.05.RESULTSOf the 250 patients enrolled, 17 patients were excluded, leaving 233 cases for analysis (117 in the TXA group and 116 in the placebo group). The demographics of the 2 groups were similar, except for a higher proportion of women in the TXA group (TXA 50% vs placebo 32%, p = 0.017). There was no significant between-groups difference in operative time (49.53 ± 18.26 vs 54.74 ± 24.49 minutes for TXA and placebo, respectively; p = 0.108) or intraoperative blood loss (55.87 ± 48.48 vs 69.14 ± 83.47 ml for TXA and placebo, respectively; p = 0.702). Postoperative blood loss measured from drain output was 62% significantly lower in the TXA group (13.03 ± 21.82 ml) than in the placebo group (34.61 ± 44.38 ml) (p < 0.001). There was no significant difference in number of dural lesions or postoperative spinal epidural hematomas, and there were no thromboembolic events.CONCLUSIONSTranexamic acid did not have a statistically significant effect on operative time, intraoperative blood loss, or complications. This study gives no evidence to support the routine use of TXA during minor lumbar decompressive surgery.Clinical trial registration no.: NCT03714360 (clinicaltrials.gov)