Risk factors of neurological deficit and pulmonary cement embolism after percutaneous vertebroplasty

Percutaneous Vertebroplasty versus Nonoperative Treatment of Osteoporotic Vertebral Fractures: A Meta-Analysis of Randomized Controlled Trials

Osteoporotic vertebral fractures frequently result in pain and decreased quality of life (QoL). The management of these fractures remains a topic of debate. Following Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, we analyzed randomized controlled trials comparing percutaneous vertebroplasty (PV) with non-operative treatment (non-OT). The outcomes of interest included pain, QoL, cement leakage, and new osteoporotic vertebral fractures after 1 year. Compared to non-OT regarding pain relief, PV yielded significant improvement at 1-2 weeks, 1 month, 6 months (standard mean difference [SMD] = -0.67 (6/14; 95% confidence interval [CI]: -1.29 to -0.06; I2 = 92%, random effects) and 1 year (mean difference = -1.07 (4/14; 95% CI: -1.97 to -0.18; I2 = 97%, random effects). For QoL, notable improvements were observed at 1 week (standard mean difference = -2.10 (5/14; 95% CI: -3.77 to -0.42; I2 = 98%, random effects) and 3 months (mean difference = -1.58 (4/14; 95% CI: -3.07 to -0.09; I2 = 96%, random effects), with 1 month, 6 months and 1 year being inconclusive. A cement leakage rate of 42% (10/14; 95% CI: 25% to 59%; I2 = 99%, random effects) was found. Further, PV did not significantly heighten the risk of new fractures within a year (odds ratio = 1.26 (6/14; 95% CI: 0.63 to 2.53; I2 = 74%, random effects). PV emerges as a promising intervention for specific time intervals regarding pain relief, especially in the extended-term analysis, and QoL, especially in the short-term analysis, compared to non-OT. However, clinicians must consider cement leakage risks. Heterogeneity among studies underscores careful patient selection.

Recent Advances in Minimally Invasive Management of Osteolytic Periacetabular Skeletal Metastases

Painful skeletal osteolytic metastases, impending pathological fractures, and nondisplaced fractures present as a devastating clinical problem in advanced stage cancer patients. Open surgical approaches provide excellent mechanical stabilization but are often associated with high complication rates and slow recovery times. Percutaneous minimally invasive interventions have arisen as a pragmatic and logical treatment option for patients with late-stage cancer in whom open surgery may be contraindicated. These percutaneous interventions minimize soft tissue dissection, allow for the immediate initiation or resumption of chemotherapies, and present with fewer complications. This review provides the most up-to-date technical and conceptual framework for the minimally invasive management of osseous metastases with particular focus on periacetabular lesions. Fundamental topics discussed are as follows: (1) pathogenesis of cancer-induced bone loss and the importance of local cytoreduction to restore bone quality, (2) anatomy and biomechanics of the acetabulum as a weight-bearing zone, (3) overview of ablation options and cement/screw techniques, and (4) combinatorial approaches. Future studies should include additional studies with more long-term follow-up to better assess mechanical durability of minimally invasive interventions. An acetabulum-specific functional and pain scoring framework should be adopted to allow for better cross-study comparison.

Advances in materials used for minimally invasive treatment of vertebral compression fractures

Vertebral compression fractures are becoming increasingly common with aging of the population; minimally invasive materials play an essential role in treating these fractures. However, the unacceptable processing-performance relationships of materials and their poor osteoinductive performance have limited their clinical application. In this review, we describe the advances in materials used for minimally invasive treatment of vertebral compression fractures and enumerate the types of bone cement commonly used in current practice. We also discuss the limitations of the materials themselves, and summarize the approaches for improving the characteristics of bone cement. Finally, we review the types and clinical efficacy of new vertebral implants. This review may provide valuable insights into newer strategies and methods for future research; it may also improve understanding on the application of minimally invasive materials for the treatment of vertebral compression fractures.

Complications of Percutaneous Vertebroplasty: A Pictorial Review

Percutaneous vertebroplasty is a minimally invasive treatment technique for vertebral body compression fractures. The complications associated with this technique can be categorized into mild, moderate, and severe. Among these, the most prevalent complication is cement leakage, which may insert into the epidural, intradiscal, foraminal, and paravertebral regions, and even the venous system. The occurrence of a postprocedural infection carries a notable risk which is inherent to any percutaneous procedure. While the majority of these complications manifest without symptoms, they can potentially lead to severe outcomes. This review aims to consolidate the various complications linked to vertebroplasty, drawing from the experiences of a single medical center.

Impact of Aspiration Percutaneous Vertebroplasty in Reducing Bone Cement Leakage and Enhancing Distribution-An Ex Vivo Study in Goat Vertebrae

Osteoporosis-induced vertebral compression fracture (OVCF) occurs commonly in people over the age of 50, especially among menopausal women. Besides conservative therapy, minimally invasive percutaneous vertebroplasty (PVP) and kyphoplasty (PKP) have been widely used in clinical treatment and achieved good efficacy. However, the leakage of bone cement (CL) during vertebroplasty (PV) is a major risk that can cause (serious) complications such as compression of the spinal cord, pulmonary embolism, or even paraplegia. In this study, we introduced a new aspiration technique with standard PV procedures (APV) to ameliorate the risk of leakage with quantitative verifications of its effectiveness. APV intends to create a differential pressure to guide the direction of cement flow within the vertebrae. To test this technique, Nubian goats' ex vivo vertebral bodies (VBs) were used to simulate the PV surgical process in humans. Results show that the proposed APV has a lower leakage rate of 13% compared to the 53% of conventional PV. Additionally, the APV approach achieves more uniform cement distribution via the 9-score method with a value of 7 ± 1.30 in contrast to 4 ± 1.78 by conventional PV.

The significance of the best puncture side bone cement/vertebral volume ratio to prevent paravertebral vein leakage of bone cement during vertebroplasty: a retrospective study

OBJECTIVES

To verify the clinical significance of the best puncture-side bone cement/vertebral volume ratio (PSBCV/VV%) and bone cement leakage in paravertebral veins during vertebroplasty.

METHODS

This was a retrospective analysis of a total of 210 patients from September 2021 to December 2022, who were divided into an observation group (110 patients) and a control group (100 patients). In the observation group, patients' preoperative computed tomography (CT) data were imported into Mimics software, and the VV was calculated using the three-dimensional (3D) reconstruction function. Then, based on the best PSBCV/VV% of 13.68% determined in a previous study, the optimal PSBCV to be injected during vertebroplasty was calculated. In the control group, vertebroplasty was performed directly using the conventional method. The incidence of cement leakage into paravertebral veins was observed postoperatively in both groups.

RESULTS

There were no statistically significant differences (P > 0.05) in the evaluated indicators between the two groups pre- or postoperatively, including the anterior vertebral margin height, mid-vertebral height, injured vertebral Cobb angle, visual analogue scale (VAS) score, and Oswestry Disability Index (ODI). Intragroup comparisons showed improvements in the anterior vertebral height, mid-vertebral height, injured vertebral Cobb angle, VAS score, and ODI after surgery compared with before surgery (P < 0.05). In the observation group, there were 3 cases of cement leakage into the paravertebral veins, for a leakage rate of 2.7%. In the control group, there were 11 cases of cement leakage into the paravertebral veins, for a leakage rate of 11%. The difference in the leakage rate between the two groups was statistically significant (P = 0.016).

CONCLUSION

In vertebroplasty, preoperative VV calculations using Mimics software, combined with calculation of the PSBCV according to the best PSBCV/VV% (13.68%), can effectively prevent leakage of bone cement into paravertebral veins and further prevent serious life-threatening complications such as pulmonary embolism.

Case report: Shock after percutaneous vertebroplasty of the 5th thoracic vertebra

Background

Percutaneous vertebroplasty (PVP) is a common treatment for osteoporotic vertebral compression fracture (OVCF). Perioperative bleeding is usually rare, so there are few reports of shock. However, we developed shock after treating a case of OVCF of the 5th thoracic vertebra with PVP.

Case presentation

An 80 years old female patient received PVP due to OVCF of the 5th thoracic vertebra. The operation was successfully completed and the patient returned to the ward safely after the operation. At 90 min after operation, she developed shock, which was induced by subcutaneous hemorrhage up to 1500 ml at the puncture site. Before using vascular embolization, transfusion and blood transfusion were used to maintain blood pressure, and local ice bag compression was used to reduce swelling and stop bleeding, which achieved successful hemostasis. She recovered and discharged after 15 days, with the hematoma having absorbed. There was no recurrence during the 17-month follow-up.

Conclusion

Although PVP is considered to be a safe and effective method to treat OVCF, the possible hemorrhagic shock still needs to arouse the vigilance of surgeons.

[Translated article] Relation between the volume of injected cement and the vertebral volume in the clinical outcome and in the appearance of leakage after a percutaneous vertebroplasty

OBJECTIVES

To assess the connection between the volume of injected cement and the vertebral volume measured through a volumetric analysis with a computed tomography (CT scan) in relation to the clinical result and the appearance of a leakage in patients who underwent a percutaneous vertebroplasty after an osteoporotic fracture.

MATERIALS AND METHODS

A prospective study of 27 patients (18 female-9 male) with an average age of 69 years old (50-81), and with a one-year follow-up. The study group presented 41 vertebrae with osteoporotic fractures that were treated with a percutaneous vertebroplasty with a bilateral transpedicular approach. The volume of injected cement was registered in each procedure and it was assessed together with the spinal volume measured through a volumetric analysis with CT scans. The percentage of the spinal filler was calculated. The appearance of cement leakage was proved by means of a simple radiography and a postoperative CT scan in all the cases. The leaks were classified according to the location in relation to the vertebral body (posterior, lateral, anterior and in the disc), and the significance (minor: smaller than the largest diameter of the pedicle; moderate: larger than the pedicle but smaller than the height of the vertebra; major: larger than the height of the vertebra).

RESULTS

The average vertebra volume was 26.1cm3, the average volume of the injected cement was 2.0cm3 and the percentage of the average filler was 9%. A total of 15 leaks in 41 vertebrae appeared (37%). The leaks were posterior in 2 vertebrae, vascular in 8 and into the disc in 5 vertebrae. They were deemed as minor in 12 cases, moderate in 1 and major in 2 cases. The preoperative assessment of the pain was as it follows: VAS (8) and Oswestry (67%). The cessation of pain was immediate after a year with the following postoperative results: VAS (1.7) and Oswestry (19%). The only complication was the temporary neuritis with a spontaneous resolution.

CONCLUSIONS

The injection of small amounts of cement, lower than the ones referred to by literary sources, obtains clinical results similar to the ones obtained by injecting higher amounts and it reduces the number of cement leaks and further complications.

Risk factor analysis of bone cement leakage for polymethylmethacrylate-augmented cannulated pedicle screw fixation in spinal disorders

Objective

To investigate the risk factors of cement leakage (CL) for polymethylmethacrylate-augmented cannulated pedicle screw (CPS) in spinal degenerative diseases and provided technical guidance for clinical surgery.

Methods

This study enrolled 276 patients with spinal degenerative disease and osteoporosis who were augmented using CPSs (835 screws in total) from May 2011 to June 2018 in our hospital. The patients' age, sex, bone mineral density (BMD), diagnosis, augmented positions, number of CPS implanted, and CL during surgery were recorded. CL was observed by postoperative computed tomography (CT) and was classified by Yeom typing.

Results

A total of 74 (74/835, 8.9%) CPSs in 64 patients leaked (64/276, 23.2%). CL was significantly correlated with the number and position of screws (P < 0.05), but not with sex, age, and BMD (P > 0.05). The position, number of CPSs, fracture, degenerative scoliosis, ankylosing spondylitis, and revision surgery were risk factors for CL (P < 0.05). Augmentation of the thoracic vertebral body, fracture, and ankylosing spondylitis were independent risk factors for Type S. Augmentation of the lumbar vertebral body, lumbar disc herniation, and lumbar spondylolisthesis were independent risk factors for Type B (P < 0.05).

Conclusions

CL has a high incidence in clinical practice. High-risk factors for leakage should be addressed to avoid serious complications. Particularly, it is necessary to develop alternative solutions once CPSs can't be used in surgery caused by CL.

Continuous cement leakage along the posterior longitudinal ligament of the intraspinal epidural during a percutaneous vesselplasty: A case report and literature review

Objective

This study aims to report one case of intraspinal epidural cement leakage caused by a novel percutaneous vesselplasty.

Methods

A clinical case report from the Orthopedic center of our hospital and a literature review. A 63-year-old woman with an L₂ osteoporotic compression fracture underwent novel kyphoplasty, percutaneous vesselplasty. This rare complication was evaluated through a literature search, and its special types are classified in more detail.

Results

The patient was hospitalized with low back pain two weeks after a fall. After auxiliary examination, a new type of percutaneous vesselplasty was performed. After the intraoperative injection of bone cement, bone cement leakage extended along the posterior longitudinal ligament and epidural space. There were no special compression symptoms of the spinal cord, and the prognosis of conservative treatment was good.

Conclusion

Although percutaneous vesselplasty is relatively safe and frequent, intraspinal leakage may occur, so sufficient preoperative evaluation, intraoperative continuous fluoroscopic monitoring, and timely evaluation of postoperative images are extremely necessary.

Risk factors for pulmonary cement embolism after percutaneous vertebroplasty and radiofrequency ablation for spinal metastases

Objective

Pulmonary cement embolism is a rare but underestimated complication of vertebroplasty due to the relative lack of study and examination. This study aims to investigate the incidence of pulmonary cement embolism in patients with spinal metastasis who undergo PVP with RFA and to analyze the relative risk factors.

Methods

A total of 47 patients were retrospectively included and classified into pulmonary cement embolism (PCE) group and non-pulmonary cement embolism (NPCE) group by comparing pre- and postoperative pulmonary CT scan images. The demographic and clinical information of the patients was obtained. Demographic data in the two groups were compared using the chi-square test for qualitative data and the unpaired t test for quantitative data. Multiple logistic regression analysis was used to identify risk factors related to pulmonary cement embolism.

Results

Pulmonary cement embolism was detected in 11 patients (23.4%), and all patients were asymptomatic and followed up regularly. Risk analysis showed that multiple segments (≥3, p=0.022), thoracic vertebrae (p=0.0008), and unipedicular puncture approach (p=0.0059) were risk factors for pulmonary cement embolism. There was a high incidence of pulmonary cement embolism if bone cement leaked into the para vertebral venous plexus in the thoracic vertebra (p<0.0001). Vein leakage of cement was related to the integrity of the vertebral cortex.

Conclusion

The number of involved vertebrae, lesion location, and puncture approach are independent risk factors for pulmonary cement embolism. There was a high incidence of pulmonary cement embolism if bone cement leaked into the para vertebral venous plexus in the thoracic vertebra. Surgeons should consider these factors when formulating therapeutic strategies.

Delayed-onset radiculopathy caused by a retropulsed bone fragment after percutaneous kyphoplasty: report of four cases and literature review

Background

Vertebral compression fractures caused by osteoporosis are common in elderly patients and are often encountered by clinical physicians. Percutaneous balloon kyphoplasty (PKP) is widely accepted as a minimally invasive procedure for effectively relieving pain and correcting deformities, but complications may occur. Radiculopathy with a delayed onset caused by a retropulsed bone fragment has not been adequately described in the literature. Thus, this article presents a case report of four cases of retropulsed bone fragment-related radiculopathy after PKP.

Case presentation

In this article, we reported that four out of 251 patients developed radiculopathy after PKP between January 2012 and January 2019 despite experiencing substantial improvements in back pain. All patients with radiculopathy were female and diagnosed with osteoporosis, and their ages ranged from 68 to 89 years. Radiculopathy occurred from 2 to 16 weeks after PKP. All four patients underwent another operation (posterior decompression and instrumentation). Three patients recovered completely, and one died of postoperative intracranial haemorrhage. A detailed imaging study with pre- and postoperative magnetic resonance imaging (MRI) revealed that retropulsed bone fragments that impinged on the corresponding root after PKP were responsible for this complication, and all four patients developed a disrupted posterior vertebral rim preoperatively. No leakage of cement or pedicle track violations were observed.

Conclusion

Although PKP is a safe and effective treatment for painful osteoporotic vertebral compression fractures, a risk of catastrophic neurological injury remains. Radiculopathy with delayed onset caused by a retropulsed bone fragment after kyphoplasty is rare and challenging to treat, and the integrity of the posterior vertebral cortex should be carefully evaluated preoperatively to prevent this complication.

Risk factors for pulmonary cement embolism associated with percutaneous vertebral augmentation: A systematic review and meta-analysis

BACKGROUND

Pulmonary cement embolism (PCE) was a rare but fatal complication for percutaneous vertebral augmentation (PVA). Thus we did a systematic review and meta-analysis of cohort studies to investigate the risk factors for PCE after PVA.

METHODS

We systematically searched PubMed, EMBASE, Cochrane library, Google Scholar, web of science, and ClinicalTrial.gov from the establishment of the database to September 2021. All eligible studies assessing the risk factors for PCE after PVA were incorporated. Dichotomous data was calculated by risk difference (RD) from Mantel-Haenszel method (M - H method); continuous data was analyzed by mean difference (MD) from Inverse-Variance method (I-V method). All variables were taken as measure of effect by fixed effect model. Heterogeneity, sensitivity, and publication bias analyses were also performed.

RESULTS

This study totally included 13 studies. According to the Newcastle-Ottawa Scale (NOS), 7 studies were considered as low quality, with NOS< 6. The others were of relatively high quality, with NOS≥6. 144/6251 patients (2.3%) had PCE after PVA. percutaneous vertebroplasty (PVP) (RD = 0.02, 95%CI: [0.01, 0.04], Z = 3.70, P < 0.01), thoracic vertebra (RD = 0.03, 95%CI: [0.01, 0.05], Z = 3.53, P < 0.01), higher cement volume injected per level (MD = 0.23, 95%CI: [0.05, 0.42], Z = 2.44, P = 0.01), more than three vertebrae treated per session (MD = -0.05, 95%CI: [-0.08, -0.02], Z = 3.65, P < 0.01), venous cement leakage (RD = 0.07, 95%CI: [0.03, 0.11], Z = 3.79, P < 0.01) were more likely to cause PCE.

CONCLUSION

This study showed that risk factors for PCE included PVP, thoracic vertebra, higher cement volume injected per level, more than three vertebrae treated per session, venous cement leakage. As a serious complication, PCE should be paid attention and avoided.

Cement leakage in percutaneous vertebroplasty for spinal metastases: a retrospective study of risk factors and clinical outcomes

Objective

The objective of this research was to investigate the risk factors of cement leakage in patients with metastatic spine tumors following percutaneous vertebroplasty (PVP).

Methods

Sixty-four patients with 113 vertebrae were retrospectively reviewed. Various clinical indexes, including age, sex, body mass index (BMI), smoking history, drinking history, chemotherapy history, radiotherapy history, primary cancer, location, other metastases, collapse, posterior wall defects, the laterality of injection, and the injected cement volume were analyzed as potential risk factors. Multivariate analyses were conducted to identify the independent risk factors.

Results

The cement leakage was found 64 in 113 treated vertebrae (56.63%), in which the incidence of each type was shown as below: spinal canal leakage 18 (15.93%), intravascular leakage around the vertebrae 11 (9.73%), and intradiscal and paravertebral leakage 35 (30.97%). Tomita classification (P = 0.019) and posterior wall destruction (P = 0.001) were considered strong risk factors for predicting cement leakage in general. The multivariate logistic analysis showed that defects of the posterior wall (P = 0.001) and injected volume (P = 0.038) were independently related to the presence of spinal canal leakage. The postoperative visual analog scale (VAS) and activities of daily living (ADL) scores showed significant differences compared with the pre-operative parameters (P < 0.05). No significant differences were found in every follow-up time between the leakage group and the non-leakage group for pain management and improvement of activities in daily life.

Conclusion

In our study, Tomita classification and the destruction of the posterior wall were independent risk factors for leakage in general. The defects of the posterior wall and injected volume were independently related to the presence of spinal canal leakage. The PVP procedure can be an effective way to manage the pain.

A nomogram for short-term recurrent pain after percutaneous vertebroplasty for osteoporotic vertebral compression fractures

In clinical practice, it was found that some patients experienced short-term recurrent pain (SRP) in the original site after PVP treatment. This study was designed to develop and validate a nomogram for predicting the potential risks of SRP after PVP, which may help to provide a painless postoperative experience and personalized health management for patients with OVCF.

INTRODUCTION

With the aging of China's population, the incidence of osteoporotic vertebral compression fractures (OVCF) has increased significantly. Percutaneous vertebroplasty (PVP) has been widely accepted due to its minimally invasive, rapid, and effective characteristics. However, it has been found that some patients have short-term recurrent pain (SRP) in the original site after surgery in practical clinical work.

METHODS

We retrospectively reviewed the clinical data of OVCF patients who were treated with PVP in our center from January 1st, 2019, to December 30th, 2020. A total of 296 patients were enrolled in the study cohort, and patients were randomly divided into the training set (70%) and validation set (30%). Univariate and multivariate logistic regression analyses were used to determine the risk factors of SRP, and a nomogram predictive model was established accordingly. The model was evaluated by calibration curve, receiver operation characteristic (ROC) curve, and decision curve analysis (DCA).

RESULTS

Among the 296 patients, 83 (27.85%) patients experienced SRP after surgery. The independent risk factors included fracture segments (OR: 14.148, 95%CI: 1.532-130.661; p < 0.019), number of surgical vertebrae (OR: 7.896, 95%CI: 3.007-20.729; p < 0.001; (OR: 12.563, 95%CI: 2.223-70.993; p = 0.004), and smoking (OR: 3.833, 95%CI: 1.219-12.052; p = 0.022). The AUC of the prediction model was 0.819 in the training set and 0.794 in the validation set. The calibration curve and DCA indicated the good performance of this nomogram.

CONCLUSION

The nomogram prediction model had satisfactory accuracy and clinical utility, which may benefit clinical decision-making for the treatment of OVCF and strengthen patient education.

Correlation analysis of the puncture-side bone cement/vertebral body volume ratio and bone cement leakage in the paravertebral vein in vertebroplasty

Objectives

To explore the influencing factors of bone cement leakage in the paravertebral vein after vertebroplasty for the treatment of osteoporotic vertebral compression fractures (OVCFs) and to determine the correlation between the puncture-side bone cement/vertebral body volume ratio and bone cement leakage in the paravertebral vein.

Methods

This was a retrospective analysis of 495 patients (585 vertebral bodies) with OVCFs treated from August 2018 to May 2021 in our hospital. The patients’ postoperative CT data were imported into Mimics software, and the three-dimensional(3D) reconstruction function was used to calculate the bone cement volume (BCV), puncture-side bone cement volume (PSBCV), and vertebral body volume (VBV); the bone cement/vertebral body volume ratio (BCV/VCV%) and puncture-side bone cement/vertebral body volume ratio (PSBCV/VCV%) were additionally calculated. Sex, Age, Body mass index(BMI), Bone density, BCV, PSBCV, VBV, BCV/VCV%, and PSBCV/VCV were compared between the leakage group and the non-leakage group. Logistic regression analysis was used to assess the correlations between the factors that statistically significantly differed between the two groups and the presence of leakage in the paravertebral veins. A receiver operating characteristic (ROC) curve was used to determine the diagnostic value of the PSBCV/VCV% and to obtain the optional cut-off value.

Results

A total of 102 males and 393 females with an average age of 72.89 (52 ~ 93) years were included in our study. There were 57 cases of cement leakage (59 vertebral bodies) in the paravertebral vein. There were 438 patients (526 vertebral bodies) without paravertebral cement leakage. Univariate analysis showed that the differences in sex, bone density, PSBCV, and PSBCV/VCV% between the two groups were statistically significant (P < 0.05). Logistic regression analysis showed that there were correlations between sex, bone density, and PSBCV/VCV% and the presence of paravertebral cement leakage (P < 0.05). The ROC curve showed that the area under the curve of the PSBCV/VCV% for the diagnosis of cement leakage in the paravertebral vein was greater than 0.65, and P < 0.05, indicating a diagnostic value. The best cut-off point for the diagnosis of paravertebral cement leakage with the PSBCV/VCV% was 13.68%, with a sensitivity of 84.7% and specificity of 37.8%.

Conclusion

Sex, bone density, and PSBCV/VCV% are risk factors for cement leakage in the paravertebral veins after vertebroplasty for the treatment of OVCFs; the PSBCV/VCV% is strongly associated with paravertebral venous leakage, and the optimal PSBCV/VCV% is 13.68%. When the PSBCV/VCV% exceeds the optimal value, the risk of cement leakage in the paravertebral vein becomes significantly increased.

Improved fixation stability for repairing pedicle screw loosening using a modified cement filling technique in porcine vertebrae

Polymethylmethacrylate (PMMA) has been applied clinically and biomechanically repair loose pedicle screws. Controversies have arisen over data due to uncontrolled cement properties, various locations and sizes of fenestrated holes in repair screws, irregular holes and different bone densities of specimens. In this study, the pullout strength was compared for two techniques, the modified technique to use PMMA to augment a threaded hole and the traditional technique with retrograde injection of a PMMA filling, for standard loose screws in porcine vertebrae. Both techniques provided statistically significant results for sufficiently randomized specimens and experimental procedures. The difference in the pullout strength between conical and cylindrical screws for the aforementioned cement augmentation techniques was also investigated. Twenty-four single-level fresh-frozen lumbar vertebrae from L1 to L6 were harvested from four mature pigs. A total of 0.8 ml of PMMA was retrograde injected into screw holes with a 5.5 mm diameter, followed by insertion of a 5.0 mm diameter repair screw in the traditional group (n = 12). A stiff threaded PMMA hole was created with a 4.5 mm tapping screw before insertion of repair screws in the modified group (n = 12). Two screw geometries were randomly assigned as cylindrical (n = 6) and conical (n = 6) in each group. The correlations between filling techniques, screw geometries and axial pullout strength were analyzed. An appropriate screw trajectory and insertion depth were confirmed using X-ray imaging prior to pullout testing in both groups. For a given screw geometry (cylindrical or conical), the pullout force of the modified group was significantly higher than that of the traditional group. There was no significant difference in the pullout force between the screw geometries for a given filling technique. The cement augmentation technique is far more influential than the screw outer geometry. The modified PMMA technique created a greater anchor force than the traditional method and could be an alternative for revision of pedicle screw loosening.

Risk Factors for Pulmonary Cement Embolism (PCE) After Polymethylmethacrylate Augmentation: Analysis of 32 PCE Cases

Objective

Pulmonary cement embolism (PCE) is an underestimated but potentially fatal complication after cement augmentation. Although the treatment and follow-up of PCE have been reported in the literature, the risk factors for PCE are so far less investigated. This study aims to identify the preoperative and intraoperative risk factors for the development of PCE.

Methods

A total of 1,373 patients treated with the polymethylmethacrylate (PMMA) augmentation technique were retrospectively included. Patients with PCE were divided into vertebral augmentation group and screw augmentation group. Possible risk factors were collected as follows: age, sex, bone mineral density, body mass index, diagnosis, comorbidity, surgical procedure, type of screw, augmented level, number of augmented vertebrae, fracture severity, presence of intravertebral cleft, cement volume, marked leakage in the paravertebral venous plexus, and periods of surgery. Binary logistic regression analyses were used to analyze independent risk factors for PCE.

Results

PCE was identified in 32 patients, with an incidence rate of 2.33% (32 of 1,373). For patients who had undergone vertebral augmentation, marked leakage in the paravertebral venous plexus (odds ratio [OR], 1.2; 95% confidence interval [CI], 0.1–10.3; p=0.000) and previous surgery (OR, 16.1; 95% CI, 4.2–61.0; p=0.007) were independent risk factors for PCE. Regarding patients who had undergone screw augmentation, the marked leakage in the paravertebral venous plexus (OR, 4.2; 95% CI, 0.5–37.3; p=0.004) was the main risk factor.

Conclusion

Marked leakage in the paravertebral venous plexus and previous surgery were significant risk factors related to PCE. Paravertebral leakage and operator experience should be concerned when performing PMMA augmentation.

Simultaneous C-arm Computed Tomography-Guided Microwave Ablation and Cementoplasty in Patients with Painful Osteolytic Bone Metastases: A Single-center Experience

PURPOSE

To evaluate the clinical benefit of simultaneous percutaneous microwave ablation (PMA) and percutaneous cementoplasty (PC) for patients with painful osteolytic bone metastases under flat-detector C-arm computed tomography (CACT).

METHODS AND MATERIALS

Thirty patients (17 men and 13 women) with 42 osteolytic metastatic tumors were prospectively treated with PMA and PC simultaneously under CACT guidance. Technical success, major complications, local tumor control status, and daily morphine consumption were recorded. Visual analog scale, Oswestry disability index, and the short-form 36 questionnaire (SF-36, 8 domains) were used to evaluate pain, functional status, and quality of life (QoL), respectively.

RESULTS

The technical success rate was 100% without major complications, and local tumor control rates were 100% and 75% for lesion diameter ≤3 cm and >3 cm, respectively. Daily morphine consumption, visual analog scale, and Oswestry disability index improved significantly from the respective pretreatment values of 75 mg, 7.4, and 59.2 to 17.3 mg, 1.7, and 22.9 at 1 week; 8.5 mg, 1.4, and 6.7 at 4 weeks; and 5.3 mg, 1.3, and 9.2 at 12 weeks, respectively (p< 0.01). The QoL assessments at 4 weeks showed significant improvements in physical function, role physical, bodily pain, general health and vitality (p < 0.05).

CONCLUSION

Simultaneous PMA and PC under CACT guidance is effective to control pain and improve QoL in selective patients with painful osteolytic bone metastases.

Freehand Minimally Invasive Pedicle Screw Fixation and Minimally Invasive Decompression for a Thoracic or Lumbar Vertebral Metastatic Tumor From Hepatocellular Carcinoma

Objective: To compare freehand minimally invasive pedicle screw fixation (freehand MIPS) combined with percutaneous vertebroplasty (PVP), minimally invasive decompression, and partial tumor resection with open surgery for treatment of thoracic or lumbar vertebral metastasis of hepatocellular carcinoma (HCC) with symptoms of neurologic compression, and evaluate its feasibility, efficacy, and safety.

Methods: Forty-seven patients with 1-level HCC metastatic thoracolumbar tumor and neurologic symptoms were included between February 2015 and April 2017. Among them, 21 patients underwent freehand MIPS combined with PVP, minimally invasive decompression, and partial tumor resection (group 1), while 26 patients were treated with open surgery (group 2). Duration of operation, blood loss, times of fluoroscopy, incision length, and stay in hospital were compared between the two groups. Pre- and postoperative visual analog scale (VAS) pain score, Oswestry Disability Index (ODI), American Spinal Injury Association (ASIA) grade, ambulatory status, and urinary continence were also recorded. The Cobb angle and central and anterior vertebral body height were measured on lateral radiographs before surgery and during follow-ups.

Results: Patients in group 1 showed significantly less blood loss (195.5 ± 169.1 ml vs. 873.1 ± 317.9 ml, P = 0.000), shorter incision length (3.4 ± 0.3 vs. 13.6 ± 1.8 cm, P = 0.000), shorter median stay in hospital (4–8/6 vs. 8–17/12 days, P = 0.000), more median times of fluoroscopy (5–11/6 vs. 4–7/5 times, P = 0.000), and longer duration of operation (204.8 ± 12.1 vs. 171.0 ± 12.0 min, P = 0.000) than group 2. Though VAS significantly decreased after surgery in both groups, VAS of group 1 was significantly lower than that of group 2 immediately after surgery and during follow-ups (P < 0.05). Similar results were found in ODI. No differences in the neurological improvement and spinal stability were observed between the two groups.

Conclusion: Freehand MIPS combined with PVP, minimally invasive decompression, and partial tumor resection is a safe, effective, and minimally invasive method for treating thoracolumbar metastatic tumors of HCC, with less blood loss, better pain relief, and shorter length of midline incision and stay in hospital.

Precise puncture combined with simplified percutaneous vertebroplasty to treat osteoporotic vertebral compression fractures: a comparative analysis with conventional percutaneous vertebroplasty

OBJECTIVE

To investigate the feasibility and clinical efficacy of precise puncture combined with simplified percutaneous vertebroplasty (PVP) for treating osteoporotic vertebral compression fractures (OVCF).

METHODS

A total of 82 patients with single-segment osteoporotic vertebral compression fractures (OVCF) treated with PVP from Dec. 2016 to Nov. 2018 were retrospectively analyzed. Among the patients, 45 cases in group A accepted precise puncture combined with simplified PVP, and 37 cases in group B underwent conventional PVP. The operative time, the number of intraoperative fluoroscopy, vertebral height restoration, postoperative bone cement distribution and bone cement leakage were observed and compared. The pain relief and improvement of quality of life (QOL) were assessed by visual analog score (VAS) and Oswestry disability index (ODI).

RESULTS

There were no differences in injected cement volume and hospital stays in group A versus group B. The operative time, the number of intraoperative fluoroscopy and material cost were lower in group A compared with group B (P<0.05). After surgery, the VAS scores, ODI, the average vertebral height and Cobb angle were obviously improved and they were significantly different from those before operation (P<0.05). There was no statistically significant difference for VAS scores, ODI, average vertebral height and Cobb angle between groups at different time points. The proportion of patients with bone cement dispersion exceeding the midline of vertebra in group A was significantly higher than that in group B (82.2% vs. 62.1%, P<0.05), whereas the bone cement leakage rate in group A was lower than that in group B (8.9% vs. 27.0%, P<0.05). Patients were followed-up for 12-23 months (mean 17.6 months) after surgery. There were 3 cases (6.6%) of adjacent vertebral fractures in group A and 2 cases (5.4%) in group B.

CONCLUSION

Precise puncture can improve the accuracy of puncture needle through pedicle to vertebral body. It is conducive to obtaining a better diffusion of bone cement across the midline with a lower bone cement leakage rate. Simplified PVP can not only reduce the surgery procedures, shorten the operative time, reduce the X-ray frequency, but also save material cost.

Trends and regional variation in vertebroplasty and kyphoplasty in Switzerland: a population-based small area analysis

Regional variation in procedure use often reflects the uncertainty about the risks and benefit of procedures. In Switzerland, regional variation in vertebroplasty and balloon kyphoplasty rates was high, although the variation declined between 2013 and 2018. Substantial parts of the variation remained unexplained, and likely signal unequal access and differing physician opinion.

PURPOSE

To assess trends and regional variation in percutaneous vertebroplasty (VP) and balloon kyphoplasty (BKP) use across Switzerland.

METHODS

We conducted a population-based analysis using patient discharge data from all Swiss acute care hospitals for 2013-2018. We calculated age/sex-standardized mean procedure rates and measures of variation across VP/BKP-specific hospital areas (HSAs). We assessed the influence of potential determinants of variation using multilevel regression models with incremental adjustment for demographics, cultural/socioeconomic, health, and supply factors.

RESULTS

We analyzed 7855 discharges with VP/BKP from 31 HSAs. The mean age/sex-standardized procedure rate increased from 16 to 20/100,000 persons from 2013 to 2018. While the variation in procedure rates across HSAs declined, the overall variation remained high (systematic component of variation from 56.8 to 6.9 from 2013 to 2018). Determinants explained 52% of the variation.

CONCLUSIONS

VP/BKP procedure rates increased and regional variation across Switzerland declined but remained at a high level. A substantial part of the regional variation remained unexplained by potential determinants of variation.

A Nomogram to Predict Intra-Spinal Canal Cement Leakage Among Elderly Patients with Spine Metastases: An Internal-Validated Model

Purpose

This study aimed to assess the risk variables for predicting intra-spinal canal cement leakage, especially among elderly patients with spine metastases after being treated with percutaneous vertebroplasty (PVP). Furthermore, we proposed and validated a nomogram to stratify risks of intra-spinal canal cement leakage.

Methods

We retrospectively analyzed 163 elderly patients (age ≧65 years) with spine metastases who underwent PVP. Patients were randomly divided into a training cohort (n=100) and a validation cohort (n=63). The multivariate logistic regression analysis was used to screen potential risk variables in the training cohort. Significant risk variables were included in the nomogram, and the nomogram was developed according to the estimates of the each included variable. The predictive effectiveness of the nomogram was validated using discrimination and calibration performance.

Results

The overall prevalence of intra-spinal canal cement leakage was 9.82% (16/163). In the training cohort, female patients (14.71%, 5/34) showed a higher rate of intra-spinal canal cement leakage as compared with male patients (4.55%, 3/66). The nomogram consisted of sex, cortical osteolytic destruction in posterior wall, and load-bearing lines of spine. The nomogram had acceptable discrimination, with the area under the receiver operating characteristic (AUROC) of 0.75 in the training cohort, 0.64 in the validation cohort, and 0.69 in the entire cohort, and also showed favorable calibration based on the goodness-of-fit test. According to the nomogram, three risk groups were developed: the low risk group had an actual probability of 7.03%, the medium risk group was 11.54%, and high risk group was 44.44%. The difference between the three groups was significant (P ˂ 0.01).

Conclusion

Intra-spinal canal cement leakage after PVP is not scarce among elderly patients. We proposed and internally validated a nomogram that is capable of calculating the risk of intra-spinal canal cement leakage among elderly patients with spine metastases. Careful surgical plan should be conducted among patients with a high risk of developing intra-spinal canal cement leakage.

Analysis on the Effect of Different Surgical Methods on the Treatment of Senile Osteoporotic Spinal Compression Fractures and the Influencing Factors of Complications

Osteoporotic fractures are a common type of fractures in the elderly, among which spinal compression fractures are more common. After the occurrence of fractures, due to the compression and burst of the vertebral body, this will lead to local kyphosis deformity and even affect the balance of the sagittal spine. In the past, conservative treatments were used for osteoporotic spinal compression fractures. Although it can relieve pain symptoms, it can easily lead to complications such as aggravation of osteoporosis and deep vein thrombosis of the lower extremities. At present, percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty (PKP) are the main clinical surgical treatments, both of which are minimally invasive surgery, short operation time, effective pain relief, and rapid postoperative recovery. Although both of them are effective, there is still controversy over the efficacy of both in the treatment of osteoporotic spinal compression fractures. The purpose of this study was to investigate the efficacy of PVP and PKP in the treatment of elderly osteoporotic spinal compression fractures and to analyze the related factors that affect the occurrence of postoperative complications. The results show that both PVP and PKP can effectively improve the pain and dysfunction of elderly patients with osteoporotic spinal compression fracture, restoration of vertebral height, and correct kyphosis, but PKP has better effect and higher safety and is worth promoting. Postoperative complications of patients are related to their age, bone mineral density, use of hormones, and antiosteoporosis treatment.

Catheter-Induced Cement Embolism During Attempted Ablation Procedure

Pulmonary cement embolism is a well-described complication of cement vertebroplasty (1,2). We describe the case of a patient with acute cement embolism during catheter insertion for attempted pulmonary vein isolation 1 month after cement vertebroplasty. We discuss the mechanism of acute cement embolism, possible sequelae, and treatment considerations. (Level of Difficulty: Intermediate.)

Intracardiac, pulmonary cement embolism in a 67-year-old female after cement-augmented pedicle screw instrumentation: A case report and review of literature

BACKGROUND

We report a case of Intracardiac, pulmonary, and intravenous cement embolism after cement-augmented pedicle screw instrumentation in treating spondylolisthesis underlying osteoporotic bone, which was successfully managed by conservative treatment. We describe the treatment and outcome of the patient, hoping to shed light on the management of bone cement embolism.

CASE SUMMARY

A 67-year-old female suffered from progressive low back pain and numbness in lower extremities for 30 years. She was diagnosed with L4 and L5 spondylolisthesis, spinal stenosis, and osteoporosis. The patient underwent spinal canal decompression, an interbody fusion of L4/5 and L5/S1, cement-augmented pedicle screw instrumentation in L4-L5 segments, and regular pedicle screw in S1 segments. Three days postoperatively, a sudden drop in oxygen saturation occurred. Computerized tomography scan confirmed Intracardiac, pulmonary, and intravenous embolism. The patient was treated conservatively by continuous low-flow oxygen inhalation, anti-coagulation, and antibiotic therapy for 1 mo and continued anticoagulation treatment for 6 mo. The patient showed no further symptoms in a 30-mo follow-up.

CONCLUSION

Intracardiac, pulmonary cement embolism after cement-augmented pedicle screw instrumentation is extremely rare. Careful clinical and radiographic evaluation is required in multiple sites of bone cement embolism. Conservative treatment may be a primary consideration in scattered emboli without life-threatening conditions, but a clinical decision should be made on an individualized basis.