A Preliminary Study on the Morphological Changes of an NiTi-Shaped Memory Alloy Stent in the Vertebral Body.

OBJECTIVE: At present, the most commonly used filler polymethyl methacrylate (PMMA) has the disadvantages of monomer toxicity, heat and leakage, and cannot be applied in young people. Therefore, finding a minimally invasive and good tissue-compatible alternative material has been a research hotspot in spine surgery in recent years. The aim of this study is to explore whether the memory alloy stent can avoid the complications of bone cement or not. METHODS: Four non-adjacent vertebral bodies of the thoracic and lumbar spine in the 18 10-month-old pigs were selected as the surgical site and were randomly divided into the scaffold group and the bone cement group. The memory alloy scaffold and PMMA (polymethyl methacrylate) bone cement were placed via percutaneous puncture, and intraoperative fluoroscopy and micro-CT were used to observe the changes in the height of scaffolds and bone cement in the vertebral body immediately, 6 weeks, and 12 weeks after operation, the microstructural parameters of the bone trabeculae (bone volume fraction, bone surface volume ratio, bone trabeculae number) were also measured. RESULTS: The memory alloy stent could expand in the vertebral body, and its height gradually increased with time; additionally, the height of the bone cement mass did not change with time (p = 0.00). New bone trabeculae could grow into the scaffold along the gap, and the volume fraction of bone, the volume ratio of bone surface area, and the number of bone trabeculae increased gradually (p = 0.00). However, the volume fraction of bone, the volume ratio of bone surface area, and the number of trabeculae in the cement block decreased gradually (p = 0.00). CONCLUSIONS: Memory alloy scaffolds have dynamic expansion characteristics in vivo, which can effectively avoid the complications of bone cement. Thus, it is beneficial to explore this minimally invasive treatment for vertebral compression fractures.

The vertebral Hounsfield units can quantitatively predict the risk of adjacent vertebral fractures after percutaneous kyphoplasty.

Background: Measuring the Hounsfield units (HU) of the vertebrae may yield diagnostic information for fracture risk. This study aimed to measure HU of vertebrae in percutaneous kyphoplasty (PKP) patients using computed tomography (CT) imaging to determine the HU measurements threshold for adjacent vertebral fracture and to assess the relationship between HU measurements and the risk of adjacent vertebral fracture. Methods: A retrospective study was conducted on consecutive patients who underwent PKP between January 2019 and October 2021 in the China-Japan Union Hospital of Jilin University. The HU of the vertebra was measured on the reconstructed CT images by 2 independent spine surgeons. The HU measurements of adjacent vertebrae and the ratio of HU measurements between the surgical vertebra and adjacent vertebrae were statistically analyzed to determine the best critical value and evaluate the prediction effectiveness and accuracy of the best critical value. Results: A total of 105 patients were identified with complete imaging and follow-up information. Of these, 47 patients (44.8%) had evidence of an adjacent vertebral fracture on follow-up imaging. The mean HU measurements of the fractured adjacent vertebra were significantly different from the mean HU measurements of the unfractured adjacent vertebra (50.94±20.59 vs. 81.74±18.97 HU; P<0.001). There was a significant difference in the ratio of HU measurements between the surgical vertebra and the fractured adjacent vertebra and between the surgical vertebra and the unfractured adjacent vertebra (26.34±17.52 vs. 14.53±9.40; P<0.001). Interactive scatter plots and receiver operating characteristic (ROC) curve showed that a HU measurement of 66.9 and a HU measurements ratio of 15.18 were the best thresholds for predicting the risk of fracture of adjacent vertebrae after PKP surgery, with an area under the curve (AUC) of 0.901 [95% confidence interval (CI): 0.822-0.953; P<0.001] and 0.874 (95% CI: 0.790-0.934; P<0.001), respectively. The prediction accuracy was 90.4% and 84.0%, respectively. Conclusions: A low mean HU measurements of adjacent vertebrae or a high ratio of the mean HU measurements of the operated vertebrae to the adjacent vertebrae are risk factors for the vulnerability of adjacent vertebrae to fracture. The risk of fracture in the adjacent vertebrae after PKP can be predicted by measuring HU.

Effect of modified Wiltse approach pedicle screw internal fixation combined with transpedicular bone grafting on the vertebral body and complications of senile osteoporotic vertebral compression fractures / 中华内分泌外科杂志

Objective:To investigate the effects of internal fixation with pedicle screw via modified Wiltse approach combined with transpedicular bone grafting on the vertebral body and complications of senile osteoporotic vertebral compression fractures (OVCF) .Methods:Ninety-four elderly patients with osteoporotic vertebral compression fractures who were admitted to Hangzhou Fuyang Traditional Chinese Medicine Orthopedics Hospital from Oct. 2018 to Oct. 2019 were selected as the research objects. The patients were divided into control group and observation group according to the random ball touch method. For 47 cases, the control group underwent posterior short-segment reduction and internal fixation combined with transpedicular bone grafting, and the observation group underwent modified Wiltse approach pedicle internal fixation combined with transpedicular bone grafting. The two groups were observed and compared in terms of surgery related indicators, the condition of the injured vertebrae, the recovery of the vertebral body, the length of hospitalization and fracture healing time, and the incidence of complications.Results:In comparison of the operation-related indexes between the two groups, the intraoperative blood loss, 3d postoperative visual analogue scale (VAS) score and operation time of the observation group were significantly lower, than those of the control group ( P<0.05) . In comparison of the condition of the injured vertebrae between the two groups, there was no significant difference in the ratio of the loss rate of the injured vertebrae Cobb angle, vertebral body sagittal plane index, and vertebral body height between the two groups before operation ( P>0.05) . The loss rates of Cobb angle and vertebral body height of the injured vertebrae in the two groups were lower than that before operation at 3 days after operation, and the sagittal index of the vertebral body was higher than before operation at 1 year after operation ( P<0.05) . The loss rate of Cobb angle and vertebral body height of the injured vertebral body in the observation group was significantly lower than that of the control group at 3 days postoperatively, and the vertebral body sagittal plane index was significantly higher than that of the control group at 1 year postoperatively ( P<0.05) . Comparing the recovery of injured vertebrae between the two groups, there was no statistically significant difference between the preoperative oswestry disability index (ODI) scores of the two groups ( P>0.05) , the improvement rate of Cobb angle and the recovery rate of vertebral body height in the observation group, ODI scores at 3 months after operation were significantly higher than those of the control group ( P<0.05) . The hospitalization time and fracture healing time of the observation group were significantly lower than those of the control group ( P<0.05) . The total incidence of complications in the observation group (4.26%) was significantly lower than the total incidence of complications in the control group (19.15%) ( P<0.05) . Conclusion:The combined use of internal fixation with pedicle screw via modified Wiltse approach combined with transpedicular bone grafting in treatment of elderly OVCF can reduce the amount of intraoperative blood loss, shorten the operation time and hospital stay and fracture healing time, improve the Cobb angle of the injured vertebra, promote the recovery of the height and function of the injured vertebra, and reduce the incidence of complications.

Cement injection and postoperative vertebral fractures during vertebroplasty.

OBJECTIVE: Vertebroplasty is the most widely used method for treating osteoporotic vertebral compression fractures (OVCF). During this procedure, bone cement is injected into the vertebral body. Fracture and additional fractures can occur adjacent to the treatment site. Thus, we studied factors causing such vertebral fractures after vertebroplasty and calculated the appropriate amount of bone cement to inject. METHODS: From September 2012 to March 2016, 187 patients with OVCF undergoing vertebroplasty were selected, and 112 patients with complete follow-up information were selected. Of these, 28 had adjacent vertebral fractures (refracture group) during the follow-up period, and 84 patients had no adjacent vertebral fractures (control group). Then, sex, age, body weight, bone mineral density (BMD), and bone cement injection (bone cement injection volume and bone fracture vertebral volume percent) were compared. RESULTS: All patients had significant pain relief within 24 h (preoperative and postoperative [24 h later] VAS scores were 7.4 ± 0.8 and 2.3 ± 0.5, respectively). The age and weight were not statistically significantly different (P > 0.05). BMD values were statistically significantly different between groups as was sex (P < 0.05). CONCLUSIONS: Bone cement injection volume, BMD values, and sex were statistically significantly related to adjacent vertebral fractures after vertebroplasty, and cement injection volumes exceeding 40.5% caused adjacent vertebral fractures.

Clinical Efficacy Analysis of Percutaneous Kyphoplasty Combined with Zoledronic Acid in the Treatment and Prevention of Osteoporotic Vertebral Compression Fractures.

OBJECTIVE: The aim of this study is to investigate the clinical efficacy of percutaneous kyphoplasty (PKP) combined with zoledronic acid (aclasta) in the treatment and prevention of osteoporotic vertebral compression fractures (OVCF). METHOD: A total of 104 patients with OVCF were treated with PKP from February 15, 2014 to January 17, 2016. All patients were randomly assigned to control and experimental groups, each group having 52 patients. All patients in the control group were treated with PKP. On the other hand, all patients in the experimental group were treated with PKP combined with aclasta. To evaluate the clinical efficacy, Visual Analogue Scale (VAS), Oswestry disability index (ODI), bone mineral density (BMD), and bone metabolism (N-MID and ß-CTX) were evaluated during the follow-up period. RESULT: One week after operation, the value of VAS and ODI improved in both groups. One year after operation, these worsened rapidly in the control group but not in the experimental group. Six months and one year after operation, the BMD improved significantly but the bone metabolism decreased significantly in the experimental group. In contrast, the BMD and bone metabolism did not change in the control group. Moreover, four patients again suffered from OVCF in the control group, and three patients had fever symptoms in the experimental group during the follow-up period. CONCLUSIONS: Results of this study indicate that the clinical efficacy of PKP combined with aclasta in the treatment and prevention of OVCF is significant.