Cimetidine (CIM) is an H2-receptor antagonist that has been used in racehorses in an attempt to reduce the occurrence of stress-related gastric ulceration. It has also been shown to produce several useful effects other than its gastric acid suppression properties. Further, it is a well documented antagonist of cytochrome P-450 (CYP) mediated oxygenation reactions. Nitric oxide (NO), a recently discovered mediator or modifier of numerous physiological functions, is generated by several forms of nitric oxide synthase (NOS), one of which is inducible (iNOS). Inducible NOS, expressed in neutrophils and macrophages as part of the inflammatory response to noxious stimuli, contains both a CYP and a CYP reductase domain. Because of the similarity of structure of iNOS and CYP, it was decided to determine whether CIM could reduce NO production, using a carrageenan inflammation model in the horse. Two experiments were conducted. In Trial 1, six female Thoroughbred horses each had three tissue chambers inserted subcutaneously on the sides of the neck. The study was divided into three treatments: 0.9% NaCl (NaCI), CIM (3 mg/kg), and aminoguanidine (AG; 25 mg/kg), an inhibitor of iNOS. Each mare received three i.v. injections 12 h apart prior to instillation of 1 mL of carrageenan into the test chamber. Blood and tissue chamber fluid (TCF) were collected serially. Concentrations of NO3- (the major metabolite of NO), albumin, total protein, CIM and AG were measured and complete cell counts and differentials were conducted. Trial 2 also used six female Thoroughbred horses implanted with at least two tissue chambers inserted subcutaneously on the sides of the neck. The study was divided into two treatments: NaCl (0.9%) and CIM (6 mg/kg). Each mare received seven i.v. injections of either NaCl or CIM 8 h apart prior to instillation of 1 mL of carrageenan into the test chamber. Blood and TCF were collected serially as before, and analysed for NO3- and CIM content. Areas under the curve (AUC) of the different parameters were calculated for the periods of -1-1, -1-3 and -1-7 days (Trial 1) and -2-1 for Trial 2. Absolute values were also compared at 4, 8 and 12 h postcarrageenan. Saline treatment did not reduce the elevated concentrations of NO3- in either plasma or TCF. Plasma, test chamber and control chamber NO3-concentrations rose from 0 to 12 h, and were very similar in all three sampled fluids. Cimetidine significantly (P< or =0.05) decreased NO3- production in plasma over the periods of -1-1, -1-3, and -1-7 days post inflammation when compared to NaCl treatment in Trial 1. Aminoguanidine and CIM decreased NO3-production in TCF for the periods -1-1, 1-3, and -1-7 days post inflammation in Trial 1 and -2-1 for Trial 2. Both CIM and AG also significantly reduced NO3-concentrations in plasma and TCF at 12 h postinitiation (Trials 1 and 2). Thus CIM, at the doses studied, was capable of reducing NO3- concentrations in this model as effectively as AG, a relatively specific inhibitor of iNOS activity.

To compare the radiographic and clinical outcomes of static versus expandable interbody cages in transforaminal lumbar interbody fusion using minimally invasive surgery (MIS-TLIF). Overview of Literature: Expandable interbody cages may potentially improve radiographic and clinical outcomes following MIS-TLIF compared to static pages, but at a potentially higher cost and increased rates of subsidence. Methods: A retrospective chart review of 1-and 2-level MIS-TLIFs performed from 2014 to 2020 was reviewed. Radiographic measurements were obtained preoperatively, 6 weeks postoperatively, and at final follow-up. Patient-reported outcome measures (PROMs) including the Oswestry Disability Index, Visual Analog Scale (VAS) back, and VAS leg were evaluated. Multivariate linear regression analysis determined the effect of cage type on the change in PROMs, controlling for demographic characteristics. Alpha was set at 0.05. Results: A total of 221 patients underwent MIS-TLIF including 136 static and 85 expandable cages. Expandable cages had significantly greater anterior (static: 11.41 mm vs. expandable: 13.11 mm, p<0.001) and posterior disk heights (static: 7.22 mm vs. expandable: 8.11 mm, p<0.001) at 1-year follow-up. Expandable cages offered similar improvements in segmental lordosis at 6 weeks (static: 1.69° vs. expandable: 2.81°, p=0.243), but segmental lordosis was better maintained with expandable cages leading to significant differences at 1-year follow-up (static: 0.86° vs. expandable: 2.45°, p=0.001). No significant differences were noted in total complication (static: 12.5% vs. expandable: 16.5%, p=0.191) or cage subsidence rates (static: 19.7% vs. expandable: 22.4%, p=0.502) groups at 1-year follow-up. Conclusions: Expandable devices provide greater improvements in radiographic measurements including anterior disk height, posterior disk height, and segmental lordosis, but this did not lead to significant improvements in PROMs, complication rates, subsidence rates, or subsidence distance.

OBJECTIVE For patients with cervical and thoracolumbar AO Spine type C injuries, the authors sought to 1) identify whether preoperative vertebral column translation is predictive of a complete spinal cord injury (SCI) and 2) identify whether preoperative or postoperative vertebral column translation is predictive of neurological improvement after surgical decompression. METHODS All patients who underwent operative treatment for cervical and thoracolumbar AO Spine type C injuries at the authors’ institution between 2006 and 2021 were identified. CT and MRI were utilized to measure vertebral column translation in millimeters prior to and after surgery. A receiver operating characteristic (ROC) curve was generated to predict the probability of sustaining a complete SCI on the basis of the amount of preoperative vertebral column translation. ROC curves were then used to predict the probability of neurological recovery on the basis of preoperative and postoperative vertebral column translation. RESULTS ROC analysis of 67 patients identified 6.10 mm (area under the curve [AUC] 0.77, 95% CI 0.650–0.892) of preoperative vertebral column translation as predictive of complete SCI. Additionally, ROC curve analysis found that 10.4 mm (AUC 0.654, 95% CI 0.421–0.887) of preoperative vertebral column translation was strongly predictive of no postoperative neurological improvement. Residual postoperative vertebral column translation after fracture reduction and instrumentation had no predictive value on neurological recovery (AUC 0.408, 95% CI 0.195–0.622). CONCLUSIONS For patients with cervical and thoracolumbar AO Spine type C injuries, the amount of preoperative vertebral column translation is highly predictive of complete SCI and the likelihood of postoperative neurological recovery.