Cardiovascular changes after pulmonary cement embolism: an experimental study in sheep

Pulmonary cement embolism is frequently observed but not a contributing factor for death in patients with cemented total hip and knee arthroplasty: a postmortem study

Purpose

Bone cement is frequently used for implant fixation in orthopaedic surgery. The occurrence of pulmonary cement embolism (PCE) in hip and knee arthroplasty has been described previously, but the exact extent and frequency have not been adequately studied. A postmortem cohort provides a unique opportunity for a more detailed analysis of this phenomenon.

Methods

Through retrospective analysis of whole-body computed tomography (CT) scans and autopsy protocols, we identified 67 cases with previous cemented total hip or knee arthroplasties. A grading system originally developed for PCE after cemented spine procedures was used. Findings were compared with two control groups: 35 individuals with previous cementless total joint arthroplasty as well as 25 individuals without evidence of prostheses.

Results

PCE was detected in 46.3% of the cases: grade 1 (31.3%), grade 2 (10.5%), and grade 3 (4.5%). No statistically significant difference was found between hip and knee arthroplasties in terms of PCE frequency. Importantly, none of the autopsy reports listed PCE as a cause of death or a contributing factor for the patients’ death. In the two control groups, only one case per group was classified as grade 1 PCE, while the remaining cases did not show any evidence of PCE.

Conclusion

The presented data reveal a high frequency of PCE in hip and knee arthroplasties, which is almost identical to previous findings in patients with cement-augmented interventions in the spine. This way, our results underline the relevance of PCE after arthroplasty, suggesting an adaptation of surgical methods to minimize this complication.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00264-022-05381-6.

Retrograde Flow Cement Leakage during Kyphoplasty

Objective: To report a rare event of a retrograde flow of cement leakage during balloon kyphoplasty and discuss the possible mechanism. Methods:We present a 55-year-old male patient, who underwent a 4-level balloon kyphoplasty for Langerhans histiocytosis that had spread to the spine. With the patient prone under general anesthesia, intrathoracic pressure was raised as a precaution measure to prevent cement embolic complications as a protocol reported elsewhere. Results:During the last vertebral body procedure (L1), cement leakage was noticed to flow downward in a retrograde fashion into the segmental vertebral vein and the procedure was immediately discontinued. Cement leak did not follow the predictable upward blood flow through the anterior or lateral segmental vein into the vena cava, but instead, the cement followed a retrograde downward path into the Batson's vein. No adverse cardiopulmonary effect was observed. Evidence of pulmonary cement embolism was detected in a routine thoracic computed tomography six week later. Conclusion:To our knowledge this is the first case in the English-speaking literature to highlight a retrograde cement intravascular flow most likely as a result of increased intrathoracic pressure.

Long-Term Outcomes of Peripheral Pulmonary Cement Embolism in Patients with Polymethylmethacrylate Augmentation: A Case Series with a Minimum Follow-Up of Five Years

BACKGROUND

Pulmonary cement embolism (PCE) is a rare but lethal complication. However, few long-term follow-up studies have investigated PCE after polymethylmethacrylate augmentation. This study aimed to investigate both the clinical and imaging outcomes of patients with PCE during a follow-up period of at least 5 years.

METHODS

A total of 1460 patients were initially included in this retrospective study. After exclusion, the clinical and imaging data were analyzed for selected patients, including the augmented level, location and length of the PCE, symptoms, therapy, migration and disintegration of the embolism, foreign body reaction, and status at follow-up.

RESULTS

Twelve female patients (age range, 56-88 years) with PCE and more than 5 years of follow-up (range, 5-13 years) were eventually included. All emboli were found in subsegment pulmonary arteries and were classified as peripheral PCE. Although 2 patients experienced transient symptoms after surgery, the majority of patients (84.6%) were asymptomatic during follow-up. No other reported emboli were observed during the follow-up period. The imaging data showed that the cement embolus could remain in the initial position throughout the long-term follow-up. In terms of the length of the PCE, there was no statistically significant difference between the values post-operation and at the last follow-up time (P > 0.05).

CONCLUSIONS

Patients with peripheral PCE do not develop known late complications. Moreover, polymethylmethacrylate can remain stable and inert in the pulmonary vasculature over the long term. Routine prophylactic anticoagulation may not be necessary for patients with peripheral PCE during follow-up.

Effect of cementing on pulmonary arterial pressure in vertebroplasty: A comparison of two techniques

BACKGROUND

Increase in intraosseous pressure and displacement of bone marrow contents leading to fat embolism and hypotension during cement injection in vertebroplasty (VP). We aimed to compare the effect of low and high viscosity cements during VP on pulmonary arterial pressure (PAP) with different cannula.

MATERIALS AND METHODS

Fifty-two patients having multilevel VP due to osteoporotic vertebral compression fractures were randomly treated either by a high viscosity cement (group A, n = 27 patients) and 2.8 mm cannula or a low viscosity cement (group B, n = 25 patients) injected through 4.2 mm cannula. PAP was measured by standard echocardiography and blood d-dimer values were recorded preoperatively, 24 h and third day after operation.

RESULTS

Mean age was 69 (62-87) years in group A and 70 (64-88) years in group B, and sex and comorbidities were similar. Average number of augmented levels was 5.4 in group A and 5.7 in group B. Preoperative mean PAP was 33 mm/Hg in group A, elevated to 41 mm/Hg on first day, and decreased to 36 mm/Hg on third day. The mean PAP in group B was 35 mm/Hg preoperatively, 51 mm/Hg on first day and 46 mm/Hg on third day (p < 0.05). The average blood d-dimer values in group A increased from 2.1 µg/mL to 2.3 µg/mL and in group B from 2.2 µg/mL to 4.2 µg/mL.

CONCLUSION

The finding of this study showed that high viscosity cement injected through a narrower cannula results in lesser PAP increase and d-dimer levels when compared to low viscosity cement injected through a wider cannula. Higher PAP and d-dimer level may show possible thromboembolism. This finding may give spine surgeons to reconsider their choice of cement type and cannula size.

The effect of mechanical aspiration of the vertebral body on pulmonary arterial pressure before cement injection in the vertebroplasty procedure

PURPOSE

The aim of this study is to compare the efficacy of the mechanical aspiration technique just prior to cement application in the standard vertebroplasty (VP).

METHODS

Forty patients were included in the study. In group A, mechanical aspiration of the cavity was done just before the cement injection and in group B aspiration of vertebral body did not perform, VP was done with the same size cannula, same injection force, same injection speed and same cement viscosity. Pulmonary arterial pressures (PAPs) and blood d-dimer values were recorded preoperatively, 24 h and 3 days after the procedure. The PAP and d-dimer data were statistically compared with Student's t-test.

RESULTS

The mean age was 71 (62-87) in A and 70 (64-88) in B. The augmented level was 6.7 in A and 6.9 in B. Cement leakage was present in four in A and six in B. Acute hypotension was observed immediately after cement injection in one patient in A and four patients in B. The preoperative mean PAP in A was 35mm/Hg and elevated to 48 mm/Hg on the first postoperative day and decreased to 42 mm/Hg on the third postoperative day. The mean PAP in B was 36 mm/Hg preoperatively, 71 mm/Hg on the first day, and 58 mm/Hg on the third day ( p < 0.05). The d-dimer values revealed a difference between groups, the PAP values significantly changed between before and after the operation in both groups ( p < 0.005).

CONCLUSION

Aspiration of the vertebral body can easily be used to decrease the risk of cement leakage and the migration of fatty particles into the pulmonary circulation.

An analysis of the causes of transient paraplegia during percutaneous vertebral augmentation under local anesthesia: A case series of 12 patients

BACKGROUND

Percutaneous vertebral augmentation (PVA) under local anesthesia has been widely used to treat osteoporotic vertebral compression fractures and vertebral body tumors. However, the occurrence of spinal cord or nerve root dysfunction may result in poor prognosis for patients. The aim of this study was to analyze the causes of transient paraplegia in 12 patients undergoing PVA.

METHODS

The medical records of 12 patients with transient paraplegia during PVA in our hospital were analyzed. Data, including operation, vertebral, anesthetic dose, operation time, recovery time, and follow-up, were extracted.

RESULTS

Among the 12 patients, ranging in age from 62 years to 83 years, with a mean age of 74 years, 8 were females and 4 were males. The average anesthetic dose injected per vertebral body was 6.38 ml. Patients required an average of 218.75 min to recover sensation and movement completely. However, the amount of anesthetic injected into each vertebral body was not related to the time required for complete recovery. Follow-up showed that all patients had regained normal bilateral sensation and motor function. Postoperative visual analog scale and Oswestry Disability Index values of the 12 patients were significantly improved compared with preoperative values.

CONCLUSION

The complication of transient paraplegia was caused by local anesthetic drugs infiltrating into the spinal canal and inhibiting nerve conduction in the spinal cord.

A Review of PMMA Bone Cement and Intra-Cardiac Embolism

Percutaneous vertebroplasty procedure is of major importance, given the significantly increasing aging population and the higher number of orthopedic procedures related to vertebral compression fractures. Vertebroplasty is a complex technique involving the injection of polymethylmethacrylate (PMMA) into the compressed vertebral body for mechanical stabilization of the fracture. Our understanding and ability to modify these mechanisms through alterations in cement material is rapidly evolving. However, the rate of cardiac complications secondary to PMMA injection and subsequent cement leakage has increased with time. The following review considers the main effects of PMMA bone cement on the heart, and the extent of influence of the materials on cardiac embolism. Clinically, cement leakage results in life-threatening cardiac injury. The convolution of this outcome through an appropriate balance of complex material properties is highlighted via clinical case reports.

First-time systematic postoperative clinical assessment of a minimally invasive approach for lumbar ventrolateral vertebroplasty in the large animal model sheep

BACKGROUND CONTEXT

Large animal models are highly recommended for meaningful preclinical studies, including the optimization of cement augmentation for vertebral body defects by vertebroplasty/kyphoplasty.

PURPOSE

The aim of this study was to perform a systematic characterization of a strictly minimally invasive in vivo large animal model for lumbar ventrolateral vertebroplasty.

STUDY DESIGN/ SETTING

This is a prospective experimental animal study.

METHODS

Lumbar defects (diameter 5 mm; depth approximately 14 mm) were created by a ventrolateral percutaneous approach in aged, osteopenic, female sheep (40 Merino sheep; 6-9 years; 68-110 kg). L1 remained untouched, L2 was left with an empty defect, and L3 carried a defect injected with a brushite-forming calcium phosphate cement (CPC). Trauma/functional impairment, surgical techniques (including drill sleeve and working canula with stop), reproducibility, bone defects, cement filling, and functional cement augmentation were documented by intraoperative incision-to-suture time and X-ray, postoperative trauma/impairment scores, and ex vivo osteodensitometry, microcomputed tomography (CT), histology, static/fluorescence histomorphometry, and biomechanical testing.

RESULTS

Minimally invasive vertebroplasty resulted in short operation times (28±2 minutes; mean±standard error of the mean) and X-ray exposure (1.59±0.12 minutes), very limited local trauma (score 0.00±0.00 at 24 hours), short postoperative recovery (2.95±0.29 hours), and rapid decrease of the postoperative impairment score to 0 (3.28±0.36 hours). Reproducible defect creation and cement filling were documented by intraoperative X-ray and ex vivo conventional/micro-CT. Vertebral cement augmentation and osteoconductivity of the CPC was verified by osteodensitometry (CPC>control), micro-CT (CPC>control and empty defect), histology/static histomorphometry (CPC>control and empty defect), fluorescence histomorphometry (CPC>control; all p<.05 for 3 and 9 months), and compressive strength measurements (CPC numerically higher than control; 102% for 3 months and 110% for 9 months).

CONCLUSIONS

This first-time systematic clinical assessment of a minimally invasive, ventrolateral, lumbar vertebroplasty model in aged, osteopenic sheep resulted in short operation times, rapid postoperative recovery, and high experimental reproducibility. This model represents an optimal basis for standardized evaluation of future studies on vertebral augmentation with resorbable and osteoconductive CPC.

Evaluation of the biphasic calcium composite (BCC), a novel bone cement, in a minipig model of pulmonary embolism

Polymethylmethacrylate (PMMA) bone cement, which is used as a filler material in vertebroplasty, is one of the major sources of pulmonary embolism in patients who have undergone vertebroplasty. In the present study, we established and evaluated two animal models of pulmonary embolism by injecting PMMA or biphasic calcium composite (BCC) bone cement with a negative surface charge. A total of 12 adults and healthy Wuzhishan minipigs were randomly divided into two groups, the PMMA and BBC groups, which received injection of PMMA bone cement and BBC bone cement with a negative surface charge in the circulation system through the pulmonary trunk, respectively, to construct animal models of pulmonary embolism. The hemodynamics, arterial blood gas, and plasma coagulation were compared between these two groups. In addition, morphological changes of the lung were examined using three-dimensional computed tomography. The results showed that both PMMA and BCC injections induced pulmonary embolisms in minipigs. Compared to the PMMA group, the BCC group exhibited significantly lower levels of arterial pressure, pulmonary artery pressure, blood oxygen pressure, blood carbon dioxide pressure, blood bicarbonate, base excess, antithrombin III and D-dimer. In conclusion, BCC bone cement with a negative surface charge is a promising filler material for vertebroplasty.

Pulmonary Artery Cement Embolism after a Vertebroplasty

Background Context. Vertebroplasty is a minimally invasive procedure most commonly used for the treatment of vertebral compression fractures. Although it is relatively safe, complications have been reported over time. Among those complications, massive cement pulmonary embolism is considered a rare complication. Here we report a case of massive diffuse cement pulmonary embolism following percutaneous vertebroplasty for a vertebral compression fracture. Study Design.

CASE REPORT

Methods. This is a 70-year-old female who underwent vertebroplasty for T11 and T12 vertebral compression fracture. Results. CT-scan revealed an incidental finding of cement embolism in the pulmonary trunk and both pulmonary arteries. Since the patient was asymptomatic, she was monitored closely and she did not need any intervention. Conclusion. Vertebroplasty is a minimally invasive procedure used for treatment of vertebral compression fracture. Despite the low rate of complications, a pulmonary cement embolism can occur. The consequences of cement embolism range widely from being asymptomatic to embolism that can cause paralysis, radiculopathy, or a fatal pulmonary embolism.

Development of an in vivo experimental model for percutaneous vertebroplasty in sheep

INTRODUCTION

Several studies have described 'open' approach techniques for cementation of sheep and goat vertebrae; however, no percutaneous technique has been developed so far for use in non-primates. The aim of this study was to develop an animal model for percutaneous vertebroplasty under clinical conditions.

METHODS

In a pilot study with dissected cadaveric ovine vertebrae, the technique and instruments as well as the optimal needle position were determined. In an in vivo animal study using 33 lumbar vertebrae of 11 sheep, a percutaneous vertebroplasty was performed under general anaesthesia. Needle position and cement volume were evaluated from high resolution, quantitative computed tomography imaging.

RESULTS

The percutaneous technique for vertebroplasty was applicable to the vertebral bodies (L1 to L5) of the ovine lumbar spine without any related adverse effects for the animals. The procedure showed a steep learning curve represented by the reduction of the distance between the actual and planned needle positioning (7.2 mm to 3.7 mm; median value) and shorter surgery times (21.3 min to 15.0 min, average) with progression of the study.

CONCLUSION

The described technique is feasible and repeatable under clinical conditions. This is the first percutaneous vertebroplasty technique for non-primates and we conclude that the sheep is a valid animal model to investigate the effects of cement augmentation in vivo.

Evaluation of the in vitro cell-material interactions and in vivo osteo-integration of a spinal acrylic bone cement

INTRODUCTION

Polymethylmethacrylate bone cements have proven performance in arthroplasty and represent a common bone filler, e.g. in vertebroplasty. However, acrylic cements are still subject to controversy concerning their exothermic reaction and osteo-integration potential. Therefore, we submitted a highly filled acrylic cement to a systematic investigation on the cell-material and tissue-implant response in vitro and in vivo.

MATERIALS AND METHODS

Cured Vertecem V+ Cements were characterized by electron microscopy. Human bone marrow-derived mesenchymal stem cell morphology, growth and differentiation on the cured cement were followed for 28 days in vitro. The uncured cement was injected in an ovine cancellous bone defect and analysed 4 and 26 weeks post-implantation.

RESULTS

The rough surface of the cement allowed for good stem cells adhesion in vitro. Up-regulation of alkaline phosphatase was detected after 8 days of incubation. No adverse local effects were observed macroscopically and microscopically following 4 and 26 weeks of implantation of the cement into drill-hole defects in ovine distal femoral epiphysis. Direct bone apposition onto the implant surface was observed resulting in extended signs of osteo-integration over time (35.2 ± 24.2% and 88.8 ± 8.8% at week 4 and 26, respectively).

CONCLUSION

Contrary to the established opinion concerning bony tissue response to implanted acrylic bone cements, we observed an early cell-implant in vitro interaction leading to cell growth and differentiation and significant signs of osteo-integration for this acrylic cement using standardized methods. Few outlined limitations, such as the use of low cement volumes, have to be considered in the interpretation of the study results.

Correlative factor analysis on the complications resulting from cement leakage after percutaneous kyphoplasty in the treatment of osteoporotic vertebral compression fracture

STUDY DESIGN

The correlative factors for complications resulting from cement leakage were retrospectively reviewed in 71 patients who underwent percutaneous kyphoplasty.

OBJECTIVE

To explore the correlative factors affecting the complications of percutaneous kyphoplasty in the treatment of osteoporotic vertebral compression fractures.

SUMMARY OF BACKGROUND DATA

Over the past decade, percutaneous kyphoplasty has been increasingly used as treatment of choice for osteoporotic vertebral compression fractures. However, current literature contains less information about the correlative factors affecting the complications resulted from cement leakage.

METHODS

In all, 71 patients with 171 vertebral compression fractures who were treated by percutaneous kyphoplasty in the department of spine surgery at our medical center were identified from the registry and were retrospectively reviewed. The treatment efficacy was determined by the assessment of change in vertebral body height, Cobb angle, visual analog scale and Oswestry functional score between preoperative, postoperative, and the latest follow-up. Complications were recorded and associated risk factors were determined and analyzed.

RESULTS

All patients had immediate and significant improvement in back pain after being treated with percutaneous kyphoplasty. Cement leakage occurred in 17 (9.94%) out of 171 vertebral bodies, including 7 paravertebral leaks, 6 leaks into intervertebral space, 3 leaks into channel of needling insertion, and 1 spinal canal leak. Four patients (5.63%) developed pulmonary complications postoperatively, one of them with confirmed diagnosis of pulmonary embolism directly caused by cement leakage. During the follow-up, we found 9 recurrence vertebral fractures in 6 patients (8.45%), including 6 adjacent vertebral bodies. Univariate analysis revealed a significant difference in preoperative vertebral body height, injected cement volume, and vertebral body wall incompetence between the cement leakage group and no cement leakage group (P<0.05). In contrast, there is no significant difference in the preoperative Cobb angle, freshness of vertebral fracture, location of operative vertebrae, and operative approach between the 2 groups (P>0.05). Multiple logistic regression analysis showed that the injected cement volume and vertebral body wall incompetence were the predominant variables associated with the complications resulting from cement leakage. The patients who had a history of pulmonary diseases were prone to develop lung-related complications after the surgery.

CONCLUSIONS

The cement viscosity, injected cement volume, vertebral body wall incompetence, and a history of pulmonary diseases were the factors affecting the complications resulting from cement leakage. The recognition of these risk factors is helpful in efforts to improve surgical technique to reduce the risk of complications after being treated by percutaneous kyphoplasty.

Effect of limited nutrition on in situ intervertebral disc cells under simulated-physiological loading

STUDY DESIGN

Whole ovine caudal intervertebral discs (IVD) were cultured in sufficient and limited nutrition under simulated-physiologic loading for 7 and 21 days.

OBJECTIVE

To study the effect of limited nutrition on disc cells embedded in their native tissue in short- and midterm whole organ disc culture.

SUMMARY OF BACKGROUND DATA

Nutrient-limited induction of disc cell death in vitro has been demonstrated and is believed to be a factor in disc degeneration. Nutrient-limited cell death and its consequences, as it relates to degeneration, have not been investigated in the intact IVD.

METHODS

Ovine IVDs with endplates were cultured for 7 and 21 days under simulated-physiologic loading, either in media with limited (2 g/L) or sufficient (4.5 g/L) glucose concentration. Cell viability, relative gene expression, newly synthesized chondroitin sulfate content, and matrix metalloproteinase (MMP) activity were measured after culture and compared to fresh tissue.

RESULTS

In sufficient glucose media, cell viability was maintained through 7 days to 21 days of culture. In limited glucose, it dropped significantly to 62% in the anulus fibrosus and to 56% in the nucleus pulposus after 7 days and remained so until 21 days (63% in the anulus fibrosus and 52% in the nucleus pulposus). No significant differences were found between culture conditions for relative gene expression, newly synthesized chondroitin sulfate and inactive and active forms of MMP13 and MMP7.

CONCLUSION

With this culture system, whole IVD explants could be maintained up to 21 days. Cell viability decreased to 50% to 60% under limited nutrition within days and remained so up to 3 weeks. The surviving cells did not compensate matrix production in this time frame.

Influence of bone marrow fat embolism on coagulation activation in an ovine model of vertebroplasty

BACKGROUND

Intraoperative cardiovascular deterioration as a result of pulmonary embolization of bone marrow fat is a potentially serious complication during vertebroplasty. The release of fatty material and thromboplastin from the bone marrow cavity during vertebroplasty may activate the coagulation cascade resulting in thrombogenesis, and pharmacological prophylaxis may therefore prevent cardiovascular complications. Thus, the effects of bone marrow fat embolism on coagulation activation during vertebroplasty were investigated with use of an animal model.

METHODS

Polymethylmethacrylate was injected into three lumbar vertebrae of six sheep in order to force bone marrow fat into the circulation. Invasive blood pressures and heart rate were recorded continuously until sixty minutes after the last injection. Cardiac output, arterial and mixed venous blood gas parameters, and coagulation parameters were measured at selected time-points. Postmortem lung biopsy specimens were assessed for the presence of intravascular fat.

RESULTS

Embolization of bone marrow fat resulted in a sudden and dramatic increase in mean pulmonary arterial pressure and a decrease in mean arterial blood pressure. There were no significant changes in any coagulation parameter from before the injection to after the injection. Intravascular fat and bone marrow cells were present in all lung lobes.

CONCLUSIONS

Injection of polymethylmethacrylate into vertebral bodies caused embolization of bone marrow fat with subsequent transient cardiovascular deterioration, but no changes in coagulation parameters were observed. Thromboembolism did not contribute to the observed cardiovascular changes.

Plasma levels of endothelin-1 after a pulmonary embolism of bone marrow fat

BACKGROUND

During orthopedic surgery, embolization of bone marrow fat can lead to potentially fatal, intra-operative cardiovascular deterioration. Vasoactive mediators may also be released from the bone marrow and contribute to these changes. Increased plasma levels of endothelin-1 (ET-1) have been observed after pulmonary air and thrombo-embolism. The role of ET-1 in the development of acute cardiovascular deterioration as a result of bone marrow fat embolization during vertebroplasty was therefore investigated.

METHODS

Bone cement was injected into three lumbar vertebrae of six sheep in order to force bone marrow fat into the circulation. Invasive blood pressures and heart rate were recorded continuously until 60 min after the last injection. Cardiac output, arterial and mixed venous blood gas parameters and plasma ET-1 concentrations were measured at selected time points. Post-mortem, lung biopsies were taken for analysis of intravascular fat.

RESULTS

Cement injections resulted in a sudden (within 1 min) and severe increase in pulmonary arterial pressure (>100%). Plasma concentrations of ET-1 started to increase after the second injection, but no significant changes were observed. Intravascular fat and bone marrow cells were present in all lung lobes.

CONCLUSION

Cement injections into vertebral bodies elicited fat embolism resulting in subsequent cardiovascular changes that were characterized by an increase in pulmonary arterial pressure. Cardiovascular complications as a result of bone marrow fat embolism should thus be considered in patients undergoing vertebroplasty. No significant changes in ET-1 plasma values were observed. Thus, ET-1 did not contribute to the acute cardiovascular changes after fat embolism.