Related factors of severe osteoporotic vertebral compression fracture and clinical outcomes of percutaneous kyphoplasty: A retrospective study.

BACKGROUND: Osteoporosis is the most common disease in postmenopausal women and the elderly, which can lead to vertebral compression fracture. OBJECTIVE: To investigate the related factors of severe osteoporotic vertebral compression fracture (SOVCF) and evaluate the long-term outcomes of percutaneous kyphoplasty (PKP) for treating SOVCF through comparison with mild OVCF (MOVCF). METHODS: From September 2015 to March 2019, 294 osteoporotic vertebral compression fracture (OVCF) patients treated with PKP were analyzed. Compression of the anterior margin of the fractured vertebral body beyond 2/3 of the original height was defined as SOVCF. Baseline data, clinical and imaging findings before and after surgery and at the last follow-up were recorded. Numerical Rating Scale (NRS) was used to evaluate low back pain, the Oswestry Disability Index (ODI) was used to evaluate activity of daily life. Anterior vertebral height (AVH) and local kyphosis angle (LKA) was used to evaluate radiographic outcomes. During the follow-up, patients with recurrent back pain were examined by MRI to identify new fractures and the incidence of adjacent vertebral fracture (AVF) was recorded. Age, sex, body mass index (BMI), dual energy X-ray absorptiometry based T value, duration of symptom, history of trauma, steroid use, and fracture site were collected for univariate logistic regression analysis Variables with a P-value of less than 0.05 were then included in multivariate analysis to determine the related factors for SOVCF. RESULTS: Logistic regression analysis indicated that longer duration of symptom (OR = 1.109, 95%CI: 1.038-1.185, P= 0.002), lower T value (OR = 0.332, 95%CI: 0.139-0.763, P= 0.001), and steroid use (OR = 31.294, 95%CI: 1.020-960.449, P= 0.049) were related factors of SOVCF. Compared with the MOVCF group, the SOVCF group had longer operation time (57.3 ± 13.51 minutes vs 44.9 ± 8.13 minutes, P< 0.001), more radiation exposure (39.9 ± 7.98 times vs 25.5 ± 4.01 times, P< 0.001), and higher cement leakage rate (55.81% vs 18.73%, P< 0.001). At the last follow-up, the SOVCF group had higher NRS (2.28 ± 0.85 vs 1.30 ± 0.71, P< 0.001), and ODI (16.23 ± 4.43 vs 12.88 ± 3.34, P< 0.001). After operation and at the last follow-up, the SOVCF group had higher LKA and lower AVH (all P< 0.05). The AVF rate at the last follow-up was higher in the SOVCF group at the last follow-up (4.78% vs 18.60%, P< 0.001). CONCLUSION: Lower T value, longer duration of disease, and steroid use were related factors of SOVCF. Compared with MOVCF, PKP for SOVCF had longer operation time, more radiation exposure, and higher cement leakage rate, and the long-term outcomes were worsen.

The correlation between self-Hounsfield units and adjacent vertebral fracture after percutaneous vertebral augmentation: a retrospective cohort study.

Background: Adjacent vertebral fracture (AVF) represents a prevalent and challenging complication after percutaneous vertebral augmentation (PVA) treatment for osteoporosis vertebral compressive fracture (OVCF). Lower bone mineral density (BMD) and intervertebral leakage are reportedly independent risk factors for AVF. Vertebral Hounsfield units (HU) measured from computed tomography (CT) scans can evaluate bone quality. This study sought to explore the risk factors associated with AVF and analyze the relationship between AVF and the Hounsfield units of adjacent vertebrae (self-HU) following PVA. Methods: In this retrospective cohort study, we included consecutive OVCF patients who presented to Xuzhou Central Hospital in Jiangsu Province, China from 1 January 2016, to 31 December 2019 for PVA treatment. Clinical and imaging data were collected, and baseline data were recorded. Patients were divided into the AVF group and the no-AVF group based on the presence of AVF during follow-up. Patients in the AVF group were further subdivided into the leakage group and the no-leakage group according to the presence of intervertebral leakage. Age, body mass index (BMI), fracture location, prior fracture, self-HU, and intervertebral leakage were included in univariate logistic regression analysis. Variables with a P value of less than 0.1 were then included in multivariate logistic regression analysis to determine the risk factors for AVF. Kaplan-Meier curves were plotted to assess the effect of intervertebral leakage on AVF using a log-rank test. Results: A total of 460 patients were included in this study and followed up for an average of 50.9 months (range, 37-83 months). Among them, 82 cases (17.83%) developed AVF and were included in the AVF group. Multivariate logistic regression analysis showed that lower self-HU [odds ratio (OR) =0.972, 95% confidence interval (CI): 0.959-0.985, P<0.001] and intervertebral leakage (OR =2.618, 95% CI: 1.415-4.844, P=0.002) were risk factors for AVF following PVA. In the AVF group, 29 patients (35.37%) with intervertebral leakage were included in the leakage group. Patients in the leakage group had a shorter time to AVF (22.07±13.83 vs. 31.42±18.73, P=0.021) and higher self-HU (78.05±16.41 vs. 64.23±20.49, P=0.002) than those in the no-leakage group. Kaplan-Meier curves showed that the fracture-free time was shorter in the leakage group compared to the no-leakage group (log-rank test, P=0.014). Conclusions: Lower self-HU and intervertebral leakage are risk factors for AVF, and higher self-HU may lead to AVF when intervertebral leakage is present.

Clinical outcomes with second injection after insufficient bone cement distribution in unilateral kyphoplasty for osteoporotic vertebral compressive fracture: a cohort retrospective study.

BACKGROUND: Bone cement distribution is an important factor affecting pain relief and long-term prognosis of osteoporotic vertebral compression fracture (OVCF) treated with vertebral augmentation. Unilateral percutaneous kyphoplasty (PKP) is the most common procedure, and insufficient bone cement distribution is more common than bilateral PKP. However, effective remedies are remain lack. In this study, sufficient cement distribution was achieved by adjusting the working channel followed by second cement injection as a remedy in cases with insufficient cement distribution, and the purpose was to evaluate the clinical outcomes by a retrospective cohort study. METHODS: From July 1, 2017 to July 31, 2020, OVCF patients treated with unilateral PKP were included in this retrospective cohort study. According to the bone cement distribution (insufficient cement distribution was confirmed when the cement did not exceed the mid line of the vertebral body in frontal film or/and the cement did not contact the upper/lower vertebral endplates in the lateral film.) and whether second injection was performed during surgery, the patients were divided into three groups. Insufficient group: patients with insufficient cement distribution confirmed by fluoroscopy or postoperative x-ray. Second injection group: patients with insufficient cement distribution was found during the procedure, and second injection was performed to improve the cement distribution. CONTROL GROUP: patients with sufficient cement distribution in one injection. The Primary outcome was cemented vertebrae re-collapse rate. The secondary outcomes included operative time, radiation exposure, cement leakage rate, VAS, ODI, and adjacent vertebral fracture rate. RESULTS: There are 34 cases in insufficient group, 45 cases in second injection group, and 241 cases in control group. There was no significant difference in baseline data and follow-up time among the three groups. PRIMARY OUTCOME: The injured vertebrae re-collapse rate of insufficient group was significantly higher than that of second injection group (42.22% vs 20.59%, P = 0.000) and control group (42.22% vs. 18.26%, P = 0.000). Kaplan-Meier survival analysis showed that there was no significant difference in the survival time between second injection group and control group (P = 0.741, Log-rank test), both of which were significant less than that in insufficient group (P = 0.032 and 0.000, respectively). SECONDARY OUTCOMES: There was no significant difference in VAS score and ODI after operation between second injection group and control group, both of which were superior to those in insufficient group (P = 0.000). At the final follow-up, there was no significant difference in VAS and ODI among the three groups (P > 0.05). The operation time of second injection group was significantly higher than that of insufficient group (53.41 ± 8.85 vs 44.18 ± 7.41, P = 0.000) and control group (53.41 ± 8.85 vs 44.28 ± 7.22, P = 0.000). The radiation exposure of the second injection group was significantly higher than that of insufficient group (40.09 ± 8.39 vs 30.38 ± 6.87, P = 0.000) and control group (40.09 ± 8.39 vs 31.31 ± 6.49, P = 0.000). The cement leakage rate of second injection group (20.59%) was comparable with that of insufficient group (24.44%) and control group (21.26%) (P = 0.877). The length of hospital stay of the second injection group (4.38 ± 1.72) was comparable with that of insufficient group (4.18 ± 1.60) and control group (4.52 ± 1.46) (P = 0.431). CONCLUSIONS: When cement distribution is insufficient during unilateral PKP, second injection may relieve early pain, reduce the incidence of cemented vertebral re-collapse and adjacent vertebral fracture, without increasing the cement leakage rate, although this procedure may increase the operation time and radiation exposure.

Investigation of Preoperative Traction Followed by Percutaneous Kyphoplasty Combined with Percutaneous Cement Discoplasty for the Treatment of Severe Thoracolumbar Osteoporotic Vertebral Compression Fractures.

OBJECTIVE: To evaluate the feasibility, clinical efficacy and imaging results of preoperative traction (PT) followed by percutaneous kyphoplasty (PKP) combined with percutaneous cement discoplasty (PCD) for treating severe thoracolumbar osteoporotic vertebral compression fractures (OVCFs). METHODS: A total of 13 patients with severe thoracolumbar OVCFs treated by PT followed by PKP combined with PCD were enrolled. General information, PT time, operation time, postoperative hospital stay, perioperative complications, visual analog scale (VAS) score, Oswestry disability index (ODI) score, local kyphosis angle, intervertebral angle (IVA), anterior vertebral height (AVH) and posterior vertebral height (PVH) were recorded. RESULTS: The average VAS score at admission was 7.4±3.5, decreased to 4.3±1.7 after PT and 2.3±0.7 three days after operation, and 1.5±0.9 at last follow-up. The average ODI score was 73.7±21.4 before operation, decreased to 26.6±9.3 three days after operation and 13.7±7.1 at last follow-up. Compared to VAS and ODI scores at admission, these at the third day after operation and last follow-up were significantly different. At admission, the IVA was 3.4°±6.8°, the disc height was 5.7±1.2mm, the AVH was 10.7±3.2mm, and the PVH was 25.7±4.2 mm, which, after PT, changed to 8.1°±7.3°, 8.6±2.6mm, 18.5±2.8mm, and 26.2±7.1mm, respectively, and the differences were significant. The average kyphotic angle was 43.4°±17.8° at admission, and decreased to 26.3°±6.7° after PT, 17.5°±8.4° three days after operation and 19.1°±10.3° at last follow-up, and the differences were significant. CONCLUSION: PT followed by PKP combined with PCD for the treatment of severe thoracolumbar OVCFs was an effective and simple procedure with satisfactory short-term clinical outcomes by relieving pain and improving kyphosis.

Preliminary report of modified expansive laminoplasty in the treatment of thoracic ossification of the ligamentum flavum.

OBJECTIVE: This study was performed to evaluate the role of posterior suspension of the laminae-ossification of the ligamentum flavum complex combined with miniplate fixation (modified expansive thoracic laminoplasty) in treating thoracic ossification of the ligamentum flavum (TOLF). METHODS: Eight patients with TOLF treated by modified expansive thoracic laminoplasty were retrospectively analyzed. Their general information, operative time, intraoperative blood loss, and postoperative complications were recorded. Neurological functional recovery was evaluated by the modified Japanese Orthopaedic Association (mJOA) score and Hirabayashi recovery rate preoperatively, postoperatively, and at the final follow-up. Preoperative and postoperative imaging was performed, and the decompression range and internal fixation positioning were evaluated. RESULTS: The mJOA score significantly improved from 4.63 points preoperatively to 9.0 points at the final follow-up (Hirabayashi recovery rate of 77.75%). Postoperative computed tomography and magnetic resonance imaging revealed sufficient decompression of the surgical segment. At the final follow-up, the internal implants were well-placed, the lamina-ligamentum flavum complex showed no significant displacement, and neurological functional recovery was satisfactory. CONCLUSION: Surgical treatment of TOLF is complicated and high-risk. Characterized by simplicity and sufficient decompression, modified expansive thoracic laminoplasty can reduce the risk of cerebrospinal fluid leakage and nerve injury with satisfactory neurological functional recovery.

Study on Low-Temperature Emission Performance of Scandate Cathode with Micro-Blade-Type Arrays.

In order to meet the requirements of high-frequency vacuum electronic devices with small size, high current density, and low working temperature, a kind of porous tungsten scandate cathode with micro-blade-type arrays was developed. The micro-blade-type arrays were fabricated by laser engraving technology. Subsequently, the cathode was prepared by a vacuum copper removal process and impregnated with active substances at high temperature. Experimental results show that the cathode exhibits excellent low-temperature electron emission performance and that the maximum pulse electron emission current density reaches 81.18 A/cm2 at 800 °C. The cathode also shows apparent combined thermal-field emission characteristics. Further analysis shows that a high electric field strength plays an important role in the electron emission of the scandate cathode. By virtue of the electric field enhancement effect formed by the fabricated micro-blade-type arrays on the cathode surface, the prepared cathode achieves high electron emission capacity.

In-Fiber Closed Cavity Interferometric High-Resolution Aqueous Solution and Alcohol Gas Refractometer.

An optical fiber interferometric refractometer for alcohol gas concentration and low refractive index (RI) solution (with 1.33-1.38 RI range) measurement is theoretically and experimentally demonstrated. The refractometer is based on a single-mode thin-core single-mode (STS) interferometric structure. By embedding a suitably sized air cavity at the splicing point, high-order cladding modes are successfully excited, which makes the sensor more suitable for low RI solution measurement. The effect of the air cavity's diameter on the sensitivity of alcohol gas concentration was analyzed experimentally, which proved that RI sensitivity will increase with an enlarged diameter of the air cavity. On this basis, the air cavity is filled with graphene in order to improve the sensitivity of the sensor; and the measured sensitivity of the alcohol gas concentration is -1206.1 pm/%. Finally, the characteristics of the single-cavity structure, graphene-filled structure and double-cavity structure sensors are demonstrated, and the linear RI sensitivities are -54.593 nm/RIU (refractive index unit), -85.561 nm/RIU and 359.77 nm/RIU, respectively. Moreover, these sensor structures have the advantages of being compact and easily prepared.

Hydrogen peroxide and glucose concentration measurement using optical fiber grating sensors with corrodible plasmonic nanocoatings.

We propose and demonstrate hydrogen peroxide (H2O2) and glucose concentration measurements using a plasmonic optical fiber sensor. The sensor utilizes a tilted fiber Bragg grating (TFBG) written in standard single mode communication fiber. The fiber is over coated with an nm-scale film of silver that supports surface plasmon resonances (SPRs). Such a tilted grating SPR structure provides a high density of narrow spectral resonances (Q-factor about 105) that overlap with the broader absorption band of the surface plasmon waves in the silver film, thereby providing an accurate tool to measure small shifts of the plasmon resonance frequencies. The H2O2 to be detected acts as an oxidant to etch the silver film, which has the effect of gradually decreasing the SPR attenuation. The etching rate of the silver film shows a clear relationship with the H2O2 concentration so that monitoring the progressively increasing attenuation of a selected surface plasmon resonance over a few minutes enables us to measure the H2O2 concentration with a limit of detection of 0.2 µM. Furthermore, the proposed method can be applied to the determination of glucose in human serum for a concentration range from 0 to 12 mM (within the physiological range of 3-8 mM) by monitoring the H2O2 produced by an enzymatic oxidation process. The sensor does not require accurate temperature control because of the inherent temperature insensitivity of TFBG devices referenced to the core mode resonance. A gold mirror coated on the fiber allows the sensor to work in reflection, which will facilitate the integration of the sensor with a hypodermic needle for in vitro measurements. The present study shows that Ag-coated TFBG-SPR can be applied as a promising type of sensing probe for optical detection of H2O2 and glucose detection in human serum.

VCSEL-powered and polarization-maintaining fiber-optic grating vector rotation sensor.

A compact fiber-optic vector rotation sensor in which a short section of polarization-maintaining (PM) fiber stub containing a straight fiber Bragg grating (FBG) is spliced to another single mode fiber without any lateral offset is proposed and experimentally demonstrated. Due to the intrinsic birefringence of the PM fiber, two well-defined resonances (i.e. orthogonally polarized FBG core modes) with wavelength separation of 0.5 nm have been achieved in reflection, and they exhibit a high sensitivity to fiber rotation. Both the orientation and the angle of rotation can be determined unambiguously via simple power detection of the relative amplitudes of the orthogonal core reflections. Meanwhile, instead of using a broadband source (BBS), the sensor is powered by a commercial vertical cavity surface emitting laser (VCSEL) with the laser wavelength matched to the PM-FBG core modes, which enables the sensor to work at much higher power levels (~15 dB better than BBS). This improves the signal-to-noise ratio considerably (~50 dB), and makes a demodulation filter unnecessary. Vector rotation measurement with a sensitivity of 0.09 dB/deg has been achieved via cost-effective single detector real time power measurement, and the unwanted power fluctuations and temperature perturbations can be effectively referenced out.