Risk factors and clinical significance of posterior slip of the proximal vertebral body after lower lumbar fusion.

BACKGROUND: Adjacent segment disease (ASD) after fusion surgery is frequently manifests as a cranial segment instability, disc herniation, spinal canal stenosis, spondylolisthesis or retrolisthesis. The risk factors and mechanisms of ASD have been widely discussed but never clearly defined. AIM: To investigate the risk factors and clinical significance of retrograde movement of the proximal vertebral body after lower lumbar fusion. METHODS: This was a retrospective analysis of the clinical data of patients who underwent transforaminal lumbar interbody fusion surgery between September 2015 and July 2021 and who were followed up for more than 2 years. Ninety-one patients with degenerative lumbar diseases were included (22 males and 69 females), with an average age of 52.3 years (40-73 years). According to whether there was retrograde movement of the adjacent vertebral body on postoperative X-rays, the patients were divided into retrograde and nonretrograde groups. The sagittal parameters of the spine and pelvis were evaluated before surgery, after surgery, and at the final follow-up. At the same time, the Oswestry Disability Index (ODI) and Visual Analogue Scale (VAS) were used to evaluate the patients' quality of life. RESULTS: Nineteen patients (20.9%) who experienced retrograde movement of proximal adjacent segments were included in this study. The pelvic incidence (PI) of the patients in the retrograde group were significantly higher than those of the patients in the nonretrograde group before surgery, after surgery and at the final follow-up (P < 0.05). There was no significant difference in lumbar lordosis (LL) between the two groups before the operation, but LL in the retrograde group was significantly greater than that in the nonretrograde group postoperatively and at the final follow-up. No significant differences were detected in terms of the |PI-LL|, and there was no significant difference in the preoperative lordosis distribution index (LDI) between the two groups. The LDIs of the retrograde group were 68.1% ± 11.5% and 67.2% ± 11.9%, respectively, which were significantly lower than those of the nonretrograde group (75.7% ± 10.4% and 74.3% ± 9.4%, respectively) (P < 0.05). Moreover, the patients in the retrograde group had a greater incidence of a LDI < 50% than those in the nonretrograde group (P < 0.05). There were no significant differences in the ODI or VAS scores between the two groups before the operation, but the ODI and VAS scores in the retrograde group were significantly worse than those in the nonretrograde group after the operation and at the last follow-up, (P < 0.05). CONCLUSION: The incidence of posterior slippage after lower lumbar fusion was approximately 20.9%. The risk factors are related to a higher PI and distribution of lumbar lordosis. When a patient has a high PI and insufficient reconstruction of the lower lumbar spine, adjacent segment compensation via posterior vertebral body slippage is one of the factors that significantly affects surgical outcomes.

The mitochondrial protein TIMM44 is required for angiogenesis in vitro and in vivo.

The mitochondrial integrity and function in endothelial cells are essential for angiogenesis. TIMM44 (translocase of inner mitochondrial membrane 44) is essential for integrity and function of mitochondria. Here we explored the potential function and the possible mechanisms of TIMM44 in angiogenesis. In HUVECs, human retinal microvascular endothelial cells and hCMEC/D3 brain endothelial cells, silence of TIMM44 by targeted shRNA largely inhibited cell proliferation, migration and in vitro capillary tube formation. TIMM44 silencing disrupted mitochondrial functions in endothelial cells, causing mitochondrial protein input arrest, ATP reduction, ROS production, and mitochondrial depolarization, and leading to apoptosis activation. TIMM44 knockout, by Cas9-sgRNA strategy, also disrupted mitochondrial functions and inhibited endothelial cell proliferation, migration and in vitro capillary tube formation. Moreover, treatment with MB-10 ("MitoBloCK-10"), a TIMM44 blocker, similarly induced mitochondrial dysfunction and suppressed angiogenic activity in endothelial cells. Contrarily, ectopic overexpression of TIMM44 increased ATP contents and augmented endothelial cell proliferation, migration and in vitro capillary tube formation. In adult mouse retinas, endothelial knockdown of TIMM44, by intravitreous injection of endothelial specific TIMM44 shRNA adenovirus, inhibited retinal angiogenesis, causing vascular leakage, acellular capillary growth, and retinal ganglion cells degeneration. Significant oxidative stress was detected in TIMM44-silenced retinal tissues. Moreover, intravitreous injection of MB-10 similarly induced oxidative injury and inhibited retinal angiogenesis in vivo. Together, the mitochondrial protein TIMM44 is important for angiogenesis in vitro and in vivo, representing as a novel and promising therapeutic target of diseases with abnormal angiogenesis.

Size selection and placement of pedicle screws using robot-assisted versus fluoroscopy-guided techniques for thoracolumbar fractures: possible implications for the screw loosening rate.

BACKGROUND: There has been increased development of robotic technologies for the accuracy of percutaneous pedicle screw placement. However, it remains unclear whether the robot really optimize the selection of screw sizes and enhance screw stability. The purpose of this study is to compare the sizes (diameter and length), placement accuracy and the loosening rate of pedicle screws using robotic-assisted versus conventional fluoroscopy approaches for thoracolumbar fractures. METHODS: A retrospective cohort study was conducted to evaluate 70 consecutive patients [34 cases of robot-assisted percutaneous pedicle screw fixation (RAF) and 36 of conventional fluoroscopy-guided percutaneous pedicle screw fixation (FGF)]. Demographics, clinical characteristics, and radiological features were recorded. Pedicle screw length, diameter, and pedicle screw placement accuracy were assessed. The patients' sagittal kyphosis Cobb angles (KCA), anterior vertebral height ratios (VHA), and screw loosening rate were evaluated by radiographic data 1 year after surgery. RESULTS: There was no significant difference in the mean computed tomography (CT) Hounsfield unit (HU) values, operation duration, or length of hospital stay between the groups. Compared with the FGF group, the RAF group had a lower fluoroscopy frequency [14 (12-18) vs. 21 (16-25), P < 0.001] and a higher "grade A + B" pedicle screw placement rate (96.5% vs. 89.4%, P < 0.05). The mean screw diameter was 6.04 ± 0.55 mm in the RAF group and 5.78 ± 0.50 mm in the FGF group (P < 0.001). The mean screw length was 50.45 ± 4.37 mm in the RAF group and 48.63 ± 3.86 mm in the FGF group (P < 0.001). The correction loss of the KCA and VHR of the RAF group was less than that of the FGT group at the 1-year follow-up [(3.8 ± 1.8° vs. 4.9 ± 4.2°) and (5.5 ± 4.9% vs. 6.4 ± 5.7%)], and screw loosening occurred in 2 out of 34 patients (5.9%) in the RAF group, and 6 out of 36 patients (16.7%) in the FGF group, but there were no significant differences (P > 0.05). CONCLUSION: Compared with the fluoroscopy-guided technique, robotic-assisted spine surgery decreased radiation exposure and optimizes screw trajectories and dimensions intraoperatively. Although not statistically significant, the loosening rate of the RAF group was lower that of than the FGT group.

[Cement augmented pedicle screw combined with vertebroplasty for the treatment of Kümmell's disease with type â ¢].

OBJECTIVE: To explore clinical effect of cement-augmented pedicle screw combined with vertebroplasty in treating Kümmell disease with type Ⅲ. METHODS: From January 2015 to December 2018, 37 patients with type Ⅲ Kümmell disease were retrospectively analyzed, including 11 males and 26 females, aged from 61 to 84 years old with an average of (68.6±4.2) years old, and the courses of disease ranged from 2 to 10 months with an average of(6.5±2.3) months. Nine patients were grade C, 20 patients were grade D and 8 patients were grade E according to Frankle grading. All patients were treated by cement-augmented pedicle screw combined with vertebroplasty. Operation time, blood loss, postoperative drainage, hospital stay and complicationswere observed after oeprtaion. Visual analogue scale(VAS), Oswestry Disability Index(ODI), height of anterior vertebral body, Cobb angle before and after operation were compared. RESULTS: All patients were followed up from 12 to 60 months with an average of (22.4±10.9) months. Operation time was (240.9±77.4) min, blood loss was (315.0±149.2) ml, postoperative drainage was (220.8±72.0) ml, hospital stay was (12.6±4.7) days. One patient occurred incision redness and 1 patient occurred infection after opertaion. No loosening of bone cement occurred. Postopertaive VAS and ODI were lower than that of before opertaion(P<0.05), height of anterior vertebral body after opertaion was larger than that of before opertaion, Cobb angle after operation was less than that of before operation (P<0.05). According to Frankle grading of never function at the latest follow up, 2 patients were grade D and 35 patients were grade E. Nerve function and quality of life was improved. CONCLUSION: Cement-augmented pedicle screw combined with vertebroplasty is a safe and effective method for the tretament of Kümmell disease with type Ⅲ.