Anatomical and pathological considerations in percutaneous vertebroplasty and kyphoplasty: a reappraisal of the vertebral venous system

Decreased extrusion of calcium phosphate cement versus high viscosity PMMA cement into spongious bone marrow-an ex vivo and in vivo study in sheep vertebrae

BACKGROUND CONTEXT

Vertebroplasty or kyphoplasty of osteoporotic vertebral fractures bears the risk of pulmonary cement embolism (3.5%-23%) caused by leakage of commonly applied acrylic polymethylmethacrylate (PMMA) cement to spongious bone marrow or outside of the vertebrae. Ultraviscous cement and specific augmentation systems have been developed to reduce such adverse effects. Rapidly setting, resorbable, physiological calcium phosphate cement (CPC) may also represent a suitable alternative.

PURPOSE

This study aimed to compare the intravertebral extrusion of CPC and PMMA cement in an ex vivo and in vivo study in sheep.

STUDY DESIGN/SETTING

A prospective experimental animal study was carried out.

METHODS

Defects (diameter 5 mm; 15 mm depth) were created by a ventrolateral percutaneous approach in lumbar vertebrae of female Merino sheep (2-4 years) either ex vivo (n=17) or in vivo (n=6), and injected with: (1) CPC (L3); (2) CPC reinforced with 10% poly(l-lactide-co-glycolide) (PLGA) fibers (L4); or (3) PMMA cement (L5; Kyphon HV-R). Controls were untouched (L1) or empty defects (L2). The effects of the cement injections were assessed in vivo by blood gas analysis and ex vivo by computed tomography (CT), micro-CT (voxel size: 67 µm), histology, and biomechanical testing.

RESULTS

Following ex vivo injection, micro-CT documented significantly increased extrusion of PMMA cement in comparison to CPC (+/- fibers) starting at a distance of 1 mm from the edge of the defect (confirmed by histology); this was also demonstrated by micro-CT following in vivo cement injection. In addition, blood gas analysis showed consistently significantly lower values for the fraction of oxygenized hemoglobin/total hemoglobin (FO₂Hb) in the arterial blood until 25 minutes following injection of the PMMA cement (p ≤ .05 vs. CPC; 7, 15 minutes). Biomechanical testing following ex vivo injection showed significantly lower compressive strength and Young modulus than untouched controls for the empty defect (40% and 34% reduction, respectively) and all three cement-injected defects (21%-27% and 29%-32% reduction, respectively), without significant differences among the cements.

CONCLUSIONS

Because of comparable compressive strength, but significantly lower cement extrusion into spongious bone marrow than PMMA cement, physiological CPC (+/- PLGA fibers) may represent an attractive alternative to PMMA for vertebroplasty or kyphoplasty of osteoporotic vertebral fractures to reduce the frequency or severity of adverse effects.

Clinical anatomy and significance of the thoracic intervertebral foramen: A cadaveric study and review of the literature

INTRODUCTION

The literature is lacking information on the anatomy and the osseous dimensions of the thoracic intervertebral foramen (IVF). We describe the anatomy of the broader area, and we proceed with morphometric data of the vertebrae and the foramina. Depiction of these features is provided with imaging and illustrations. The purpose of this paper is to survey and present the anatomy of the foramen as a whole and provide baseline statistical data.

MATERIALS AND METHODS

We review relevant literature, and we present data obtained from skeletal samples of known population and sex. One hundred and nineteen thoracic vertebrae of ten cadaveric spines from the prefecture of Eastern Macedonia and Thrace, Greece, were selected. Statistical analysis measuring the vertical height and the foraminal width of each vertebra was made in accordance with sex.

RESULTS

No statistically important differences referring to the descriptive data of both sexes were found. However, statistically, important positive correlation between the vertebral height and the foraminal width was observed, especially for men. The components of the foramen including arteries and veins passing through or neighboring it, and the spinal nerves and roots are described and depicted.

CONCLUSIONS

The osseous thoracic IVF reveals a glimpse of the in vivo structure and alterations of its width may be present in back pain and other degenerative diseases. Although it is crucial for surgeries and other interventional procedures of the thoracic spine, little is known about the precise anatomy and dimensions of this anatomical landmark.

Effects of cement augmentation on the mechanical stability of multilevel spine after vertebral compression fracture

BACKGROUND

Studies on the effects of cement augmentation or vertebroplasty on multi-level spine after vertebral compression fractures are lacking. This paper seeks to establish a 3-vertebrae ovine model to determine the impact of compression fracture on spine biomechanics, and to discover if cement augmentation can restore mechanical stability to fractured spine.

METHODS

Five lumbar spine segments (L1-L3) were obtained from 5-year-old female Merino sheep. Standardized wedge-compression fractures were generated in each L2 vertebra, and then augmented with polymethyl methacrylate (PMMA) cement mixed with 30% barium sulphate powder. Biomechanical pure moment testing in axial rotation (AR), flexion/extension (FE) and lateral bending (LB) was carried out in the intact, fractured and repaired states. Range of motion (ROM) and neutral zone (NZ) parameters were compared, and plain radiographs taken at every stage.

RESULTS

Except for a significant increase in ROM between the intact and fractured states in AR between L1 and L2 (P<0.05), there were no other significant differences in ROM or NZ between the other groups. There was a trend towards an increase in ROM and NZ in all directions after fracture, but this did not reach significance. Normal biomechanics was only minimally restored after augmentation.

CONCLUSIONS

Results suggest that cement augmentation could not restore mechanical stability of fractured spine. Model-specific factors may have had a role in these findings. Caution should be exercised when applying these results to humans.

Evaluation of surgical outcome of Jack vertebral dilator kyphoplasty for osteoporotic vertebral compression fracture-clinical experience of 218 cases

Background

Osteoporotic vertebral compression fracture is a serious complication of osteoporosis. Various vertebral kyphoplasty surgeries, which have their own unique features, are commonly used for osteoporotic vertebral compression fracture. Based on the anatomic property of the thoracolumbar vertebral pedicle that its horizontal diameter is twice that of the vertical diameter, we designed Jack vertebral dilator for better restoration of the vertebral height by manipulating the mechanical force.

Methods

A total of 218 patients (236 vertebrae) with osteoporotic vertebral compression fracture were treated with Jack vertebral dilator. Surgery was successfully completed in all cases, and all the 218 patients were followed up for an average of 14.2 months (range 3 to 30 months).

Results

Bone cement leakage occurred in 12 cases, but no symptoms were reported. No other complications were noticed. The VAS scores were 8.2 ± 1.3, 1.7 ± 0.9, and 1.8 ± 0.8 and the ODI was 78.2 ± 13.3 %, 18.5 ± 7.3 %, and 20.9 ± 6.8 % before surgery and 1 week after surgery and at the final follow-up, respectively. The anterior vertebral body height was 19.3 ± 3.2, 25.1 ± 2.6, and 24.9 ± 2.6 mm and the central vertebral body height was 18.7 ± 3.0, 24.8 ± 3.0, and 24.5 ± 2.9 mm before surgery and 1 week after surgery and at the final follow-up, respectively. Cobb angle was 16.2° ± 6.6°, 8.1° ± 5.6°, and 8.5° ± 5.6° before surgery and 1 week after surgery and at the final follow-up, respectively.

Conclusions

Jack vertebral dilator kyphoplasty for osteoporotic vertebral compression fracture is safe, feasible, and effective and has the prospect of further broad application in the future.

Electronic supplementary material

The online version of this article (doi:10.1186/s13018-016-0371-4) contains supplementary material, which is available to authorized users.

Pulmonary cement embolization after vertebroplasty, an uncommon presentation of pulmonary embolism: A case report and literature review

Pulmonary Cement Embolization (PCE) is a rare complication of vertebroplasty surgery. There is no clear guideline for management of this entity. There is no definite protocol for anticoagulation in PCE. This is a case report of our patient who was diagnosed to have Pulmonary Cement Embolization, which was quite significant involving both lungs. She was successfully managed without long term anticoagulation.

The effect of void creation prior to vertebroplasty on intravertebral pressure and cement distribution in cadaveric spines with simulated metastases

Background

For osteoporosis or spinal metastases, percutaneous vertebroplasty is effective in pain relief and improvement of mobility. However, the complication rate (cement extravasation and fat embolisms) is relatively higher in the treatment of spinal metastases. The presence of tumor tissue plays a significant role in intravertebral pressure and cement distribution and thereby affects the occurrence of complications. We investigated the effect of void creation prior to vertebroplasty on intravertebral pressure and cement distribution in spinal metastases.

Methods

Eighteen vertebrae (T8–L4) from five cadaveric spines were randomly allocated for two groups (group with and without void) of nine vertebrae each. Defect was created by removing a central core of cancellous bone in the vertebral body and then filling it with 30% or 100% fresh muscle paste by volume to simulate void creation or no void creation, respectively. Then, 20% bone cement by volume of the vertebral body was injected into each specimen through a unipedicular approach at a rate of 3 mL/min. The gender of the donor, vertebral body size, bone density, cement volume, and intravertebral pressure were recorded. Then, computed tomography scans and cross sections were taken to evaluate the cement distribution in vertebral bodies.

Results

No significant difference was found between the two groups in terms of the gender of the donor, vertebral body size, bone density, or bone cement volume. The average maximum intravertebral pressure in the group with void creation was significantly lower than that in the group without void creation (1.20 versus 5.09 kPa, P = 0.001). Especially during the filling of void, the difference was more pronounced. Void creation prior to vertebroplasty allowed the bone cement to infiltrate into the lytic defect.

Conclusions

In vertebroplasty for spinal metastases, void creation produced lower intravertebral pressure and facilitated cement filling. To reduce the occurrence of complication, it may be an alternative to eliminate the tumor tissue to create a void prior to cement injection.

Pulmonary Cement Embolism following Percutaneous Vertebroplasty

Percutaneous vertebroplasty is a minimal invasive procedure that is applied for the treatment of osteoporotic vertebral fractures. During vertebroplasty, the leakage of bone cement outside the vertebral body leads to pulmonary cement embolism, which is a serious complication of this procedure. Here we report a 48-year-old man who was admitted to our hospital with dyspnea after percutaneous vertebroplasty and diagnosed as pulmonary cement embolism.

Vertebroplasty using bisphosphonate-loaded calcium phosphate cement in a standardized vertebral body bone defect in an osteoporotic sheep model

In the context of bone regeneration in an osteoporotic environment, the present study describes the development of an approach based on the use of calcium phosphate (CaP) bone substitutes that can promote new bone formation and locally deliver in situ bisphosphonate (BP) directly at the implantation site. The formulation of a CaP material has been optimized by designing an injectable apatitic cement that (i) hardens in situ despite the presence of BP and (ii) provides immediate mechanical properties adapted to clinical applications in an osteoporotic environment. We developed a large animal model for simulating lumbar vertebroplasty through a two-level lateral corpectomy on L3 and L4 vertebrae presenting a standardized osteopenic bone defect that was filled with cements. Both 2-D and 3-D analysis of microarchitectural parameters demonstrated that implantation of BP-loaded cement in such vertebral defects positively influenced the microarchitecture of the adjacent trabecular bone. This biological effect was dependent on the distance from the implant, emphasizing the in situ effect of the BP and its release from the cement. As a drug device combination, this BP-containing apatitic cement shows good promise as a local approach for the prevention of osteoporotic vertebral fractures through percutaneous vertebroplasty procedures.

Spinal cord ischemia: practical imaging tips, pearls, and pitfalls

Ischemia of the spinal cord is a rare entity with a poor prognosis. Brain ischemia is no longer a diagnostic challenge; on the contrary, ischemia of the spinal cord remains difficult, particularly in children. In this article, we illustrate the principal causes in children and adults, clinical presentation, different techniques for the diagnosis by MR imaging (diffusion, spinal MR angiography, and 1.5 versus 3T), pathophysiology, and differential diagnosis. We will discuss current knowledge, perspectives, and pitfalls.

Basivertebral foramen could be connected with intravertebral cleft: a potential risk factor of cement leakage in percutaneous kyphoplasty

BACKGROUND CONTEXT

Among different types of cement leakage in percutaneous kyphoplasty (PKP) for osteoporotic vertebral body compression fractures, leaks into the spinal canal are considered to be the most common complication. One potential structure causing this type of cement leakage is the potential connection between the basivertebral foramen and the intravertebral cleft, which is revealed clearly on magnetic resonance (MR) images, but is often ignored in the literature.

PURPOSE

The purpose of this study is to assess the incidence rate of different types of cement leakage in PKP with or without intravertebral clefts and to determine whether the basivertebral foramen could be connected to the intravertebral cleft.

STUDY DESIGN

This study is a retrospective assessment of the presence of an intravertebral cleft in osteoporotic vertebral bodies and the different types of cement leakage after PKP on radiographs, computed tomographic (CT) scans, and MR images.

PATIENT SAMPLE

A total of 164 consecutive patients underwent PKP to treat 204 osteoporotic vertebral compression fractures.

OUTCOME MEASURES

Outcome measures include the occurrence of different types of cement leakage in the groups with an intravertebral cleft and without intravertebral clefts.

METHODS

A total of 204 vertebrae in 164 consecutive patients who underwent PKP to treat osteoporotic vertebral compression fractures were classified into two patterns based on preoperative radiographs, CT scans, and/or MR images of the treated levels: cleft pattern (with an intravertebral cleft in the vertebral body) and trabecular pattern (without intravertebral clefts). When an intravertebral cleft was identified, the investigators examined the basivertebral foramen and looked for a communication between the two structures on three-dimensional CT scans and MR images. On direct postoperative images, the patterns of cement leakage were classified as five types: type A, through a cortical defect into the paraspinal soft tissues; type B, through the basivertebral foramen; type C, via the needle channel; type D, through a cortical defect into the disc space; and type E, via the paravertebral vein. The association of the distribution of the cement leakage and the presence of an intravertebral cleft was analyzed retrospectively. Moreover, the association of type B leakage with the communication between the basivertebral foramen and the intravertebral cleft was also assessed.

RESULTS

The average interobserver kappa values for determining the type of cement leakage and the presence of intravertebral cleft were 0.916 (range, 0.792-1) and 0.935, respectively. In 41 of 204 vertebrae (19.9%), an intravertebral cleft was confirmed on preoperative images. A communication between the intravertebral cleft and the basivertebral foramen was seen in 10 vertebrae (24.4%). Cement leakage was 36.2% in the group with a trabecular pattern and 41.5% in the group with a cleft pattern (p>.05). Leaks through the basivertebral foramen (type B; N=30, 14.7%) and through cortical defects into the disc space (type D; N=14, 6.9%) were more common than other types. Twenty of 163 vertebrae with the trabecular pattern (12.3%) and 10 of 41 vertebrae with the cleft pattern (24.4%) were identified as type B leaks, which reached statistical significance (p<.05). There was no statistical difference between the trabecular pattern and the cleft pattern on other types of leaks.

CONCLUSIONS

Type B leaks are more common in vertebrae with an intravertebral cleft, which supports the presence of a connection between an intravertebral cleft and the basivertebral foramen. Thus, care must be taken when PKP is performed in these patients to avoid direct cement leakage into the spinal canal through the basivertebral foramen.

Pulmonary cement embolization after vertebroplasty requiring pulmonary wedge resection

BACKGROUND

Pulmonary cement embolization after vertebroplasty is a well-known complication but typically presents with minimal respiratory symptoms. Although this rare complication has been reported, the current literature does not address the need for awareness of symptoms of potentially devastating respiratory compromise.

CASE DESCRIPTION

We present the case of a 29-year-old man who underwent T11 vertebroplasty and subsequently had chest pain develop several days later. His right lower lung lobe had infarcted owing to massive cement embolization to his pulmonary arterial circulation. Open pulmonary wedge resection and embolectomy were performed. The patient recovered from the embolectomy but had chronic, persistent respiratory symptoms after surgery.

LITERATURE REVIEW

Operative management of vertebral compression fractures has included percutaneous vertebroplasty for the past 25 years. The reported incidence of pulmonary cement emboli after vertebroplasty ranges from 2.1% to 26% with much of this variation resulting from which radiographic technique is used to detect embolization. Symptoms of pulmonary cement embolism can occur during the procedure, but more commonly begin days to weeks, even months, after vertebroplasty. At least six deaths from cement embolization after vertebroplasty have been reported. Most cases of pulmonary cement emboli with cardiovascular and pulmonary complications are treated nonoperatively with anticoagulation. Endovascular removal of large cement emboli from the pulmonary arteries is not without risk and sometimes requires open surgery for complete removal of cement pieces.

CLINICAL RELEVANCE

Pulmonary cement embolism is a potentially serious complication of vertebroplasty. If a patient has chest pain or respiratory difficulty after the procedure, chest radiography and possibly advanced chest imaging studies should be performed immediately.

Intraoperative Life Threatening Acute Lung Injury Due to Multiple Septic Pulmonary Emboli during Transpedicular Biopsy and Kyphoplasty

A 55-year-old gentleman was presented to our clinic two months after a trivial fall with persistent pain, gibbus at the thoraco-lumbar junction and intact neurology. Radiological and laboratory investigations suggested osteoporotic fracture or metastasis. Due to unremitting pain, a plan was made to do transpedicular biopsy and kyphoplasty. Biopsy needles were inserted into both pedicles and an attempt at aspiration was made. Since the aspirate was dry, 5 to 6 mL of saline was injected through one needle and an attempt at aspiration was made through the other. Three-millilitres of sero-sanguineous material mixed with pus came out and kyphoplasty was deferred. After extubation, the patient developed severe bronchospasm and was transferred to the intensive care unit. Investigations confirmed multiple septic pulmonary emboli and the patient recovered completely after treatment. This report highlights that confirmation of the diagnosis is essential before performing any procedure that increases the intravertebral pressure and the place should have appropriate facilities to manage complications.

Percutaneous vertebroplasty using fresh frozen allogeneic bone chips as filler

Background

Vertebroplasty is not free from cement related complications. If an allograft is used as a filler, most of them can be averted.

Methods

Forty consecutive cases of osteoporotic vertebral fracture were divided into two groups by self-selection. The study and the control groups underwent vertebroplasty with fresh frozen allogeneic bone chips and bone cement, respectively. Clinical results were assessed at preoperation, postoperative day 1 and months 3, 6, and 12 by 10-grade visual analog scale (VAS), and radiological results were assessed at the same time by vertebral kyphotic angle (VKA) and local kyphotic angle (LKA). The results were compared within and between the groups. Survival function was analyzed. The criteria of an event were clinical or radiological deterioration versus pre-index surgery state.

Results

VAS was improved in the study group from 8.4 ± 0.8 to 5.2 ± 1.4, 6.4 ± 1.2, 5.5 ± 2.7, and 3.7 ± 1.4 at postoperative day 1 and months 3, 6, and 12, respectively, and in the control group from 8.4 ± 1.2 to 3.2 ± 1.1, 3.2 ± 1.7, 3.2 ± 2.7, and 2.5 ± 1.7, respectively (within group, p < 0.001; between groups, p < 0.001). VKA was improved in the study group from 18.9° ± 8.0° to 15.2° ± 6.1° (p = 0.046) and in the control group from 14.7° ± 5.2° to 10.3° ± 4.7° (p < 0.001) at postoperative day 1. LKA was not improved in the study group but was improved in the control group from 16.8° ± 11.7° to 14.3° ± 9.6° (p = 0.015). Correction angle was 2.7° ± 4.6°, -7.9° ± 5.3°, -7.2° ± 5.2°, and -7.4° ± 6.3° at postoperative day 1 and months 3, 6, and 12, respectively, in the study group and 4.3° ± 3.7°, 0.7° ± 3.6°, 0.7° ± 4.2°, and 0.1° ± 4.4°, respectively, in the control group. Correction loss was significant in both groups (p < 0.001) and more serious in the study group (p < 0.001). The 6-month survival rate was 16.7% in the study group and 64.3% in the control group (p = 0.003; odds ratio, 5.250).

Conclusions

In treatment of osteoporotic vertebral fracture, fresh frozen allogeneic bone chips are not recommendable as a filler for its worse results than bone cement.

Venous drainage of the spine and spinal cord: a comprehensive review of its history, embryology, anatomy, physiology, and pathology

Venous drainage of the spine and spinal cord is accomplished through a complex network of venous structures compartmentalized to intrinsic, extrinsic, and extradural systems. As the literature on this topic is scarce, the following review was performed to summarize the available literature into a single coherent format. The medical literature on the spinal venous system was reviewed using online sources as well as historical documents that were not available online in regard to history, embryology, anatomy, and physiology with a particular emphasis on the pathology affecting this system. The spinal venous system is complex and variable. Proper understanding of all aspects is critical for the management of the pathology that results from its failure.

Perispinal etanercept for post-stroke neurological and cognitive dysfunction: scientific rationale and current evidence

There is increasing recognition of the involvement of the immune signaling molecule, tumor necrosis factor (TNF), in the pathophysiology of stroke and chronic brain dysfunction. TNF plays an important role both in modulating synaptic function and in the pathogenesis of neuropathic pain. Etanercept is a recombinant therapeutic that neutralizes pathologic levels of TNF. Brain imaging has demonstrated chronic intracerebral microglial activation and neuroinflammation following stroke and other forms of acute brain injury. Activated microglia release TNF, which mediates neurotoxicity in the stroke penumbra. Recent observational studies have reported rapid and sustained improvement in chronic post-stroke neurological and cognitive dysfunction following perispinal administration of etanercept. The biological plausibility of these results is supported by independent evidence demonstrating reduction in cognitive dysfunction, neuropathic pain, and microglial activation following the use of etanercept, as well as multiple studies reporting improvement in stroke outcome and cognitive impairment following therapeutic strategies designed to inhibit TNF. The causal association between etanercept treatment and reduction in post-stroke disability satisfy all of the Bradford Hill Criteria: strength of the association; consistency; specificity; temporality; biological gradient; biological plausibility; coherence; experimental evidence; and analogy. Recognition that chronic microglial activation and pathologic TNF concentration are targets that may be therapeutically addressed for years following stroke and other forms of acute brain injury provides an exciting new direction for research and treatment.

Epidural and intradural cement leakage following percutaneous vertebroplasty: a case report

A 48-year-old woman presented with severe bilateral leg pain, urinary incontinence, and paraparesis following vertebroplasty in another hospital 15 days earlier. Computed tomography and magnetic resonance imaging showed blocks of epidural and intradural cement from T12 to L1 with neurological compression. She underwent corpectomy of L1 and removal of extradural cement, followed by anterior reconstruction with an expandable cage and dual rodscrew construct (Kaneda system). Postoperatively, the patient had minimal improvement in leg pain and neurological deficit. Computed tomographic myelography was therefore performed and revealed complete blockage, which is suspected to be due to intradural cement leakage. The patient underwent posterior durotomy and removal of the cement. Postoperatively, the patient reported immediate pain relief. Her neurological status gradually improved over months. At the 2-year follow-up, the patient was able to walk with support and to perform activities of daily living and had regained her urinary function.

PMMA embolization to the left dorsal foot artery during percutaneous vertebroplasty for spinal metastases

PURPOSE

Distal arterial embolization to the foot with PMMA during vertebral augmentation has not been previously reported. We report a rare case of distal PMMA embolization to the dorsal foot artery during ipsilateral percutaneous lumbar vertebral augmentation in a patient with spinal osteolytic metastases.

METHODS

A 68-year-old woman was admitted because of severe disabling low back pain. Plain roentgenograms, MRI and CT-scan revealed osteolysis in the L4 and L5 vertebral bodies with prevertebral soft tissue involvement. Percutaneous vertebroplasty with PMMA was performed in L2 to L5 vertebrae under general anesthesia. Intraoperatively, leakage into the segmental vessels L3 and L5 was observed.

RESULT

Four hours after the procedure the clinical diagnosis of acute ischemia and drop foot on the left was made. CT-angiography justified linear cement leakage in the course of the left third lumbar vein and fifth lumbar artery, and to the ipsilateral common iliac artery. The patient was treated with low molecular heparin and the ischemia resolved without further sequelae 1 week postoperatively.

CONCLUSION

PMMA leakage is a complication associated with vertebroplasty and kyphoplasty. Although the outcome of the PMMA embolization to the vessels resolved without sequelae, in our case spine surgeons and interventional radiologists should be aware on this rare complication in patients with osteolytic vertebral metastases even when contemporary cement containment techniques are used.

Spinal manifestation of hydatid disease: a case series of 36 patients

OBJECTIVE

Vertebral hydatid cysts are found in <1% of all cases of hydatidosis. The pathology has an infiltrative malignant nature, affecting the vertebral body with possible extension in the epidural space. This pathomechnism is associated with a high rate of morbidity, mortality, and relapse. Decompressive surgery combined with antihelminthic therapy is recommended to eradicate the disease and prevent recurrence.

METHODS

Between 1990 and 2007, 36 patients with a mean age of 31 years were diagnosed as having spinal hydatid disease and underwent surgery on several occasions for multiple recurrences. Combined chemotherapy with albendazole also was given.

RESULTS

Initial surgery and chemotherapy steadied clinical progression and functional deterioration, but with a recurrence rate of 89% and an average time to disease recurrence of 2.5 years, did not improve the known malignant course of disease in comparison to the literature.

CONCLUSION

The devastating and malignant course of this disease, which affects mostly young patients, demands continuous development of preventive care in endemic regions, the early detection and screening of the diseased patients, and eventually the advancement of the combined medical and surgical treatment.

Cement pulmonary embolism after vertebroplasty

In recent years, the use of vertebral cementing techniques for vertebroplasty and kyphoplasty has spread for the treatment of pain associated with osteoporotic vertebral compression fractures. This is also associated with the increased incidence of complications related with these procedures, the most frequent being originated by leakage of cementation material. Cement can escape into the vertebral venous system and reach the pulmonary circulation through the azygous system and cava vein, producing a cement embolism. This is a frequent complication, occurring in up to 26% of patients undergoing vertebroplasty but, since most patients have no clinical or hemodynamical repercussion, this event usually goes unnoticed. However, some serious, and even fatal cases, have been reported. We report the case of a 74-year-old male patient who underwent vertebroplasty for persistent pain associated with osteoporotic L3 vertebral fracture and who developed a cement leak into the cava vein and right pulmonary artery during the procedure. Although he developed a pulmonary cement embolism, the patient remained asymptomatic and did not present complications during follow-up.

Intravertebral pressure gradient during vertebroplasty

OBJECTIVE

Intravertebral pressure (IP) is considered a possible factor influencing cement leakage in vertebroplasty (VP). Reports of measuring IP during the injection of the cement reveal rather low values in the periphery of the vertebral body but fail to determine the situation in the center. Hypothesizing there is a significant IP gradient between both areas intravertebral pressure measurements were conducted in a comparative biomechanical study.

METHODS

VP was performed in ten lumbar cadaveric spines. A pressure sensor was either placed in the center or in the periphery of the vertebral body, while bone cement was delivered in 1.5-cc increments. Volume flow, cement mixing time, and room temperature were standardized and kept constant during cement injection.

RESULTS

During the administration of the first 1.5 cc of bone cement, the central IP (C-IP) increased to 23.6 kPa and the peripheral IP (P-IP) to 0.9 kPa on average. With the second injection, the mean C-IP was 42.8 kPa while the mean P-IP was 3.8 kPa. During the 3rd filling, C-IP averaged 69.9 kPa and P-IP 12.8 kPa, respectively. At the last increment, C-IP was at 70.7 kPa and P-IP at 24.5 kPa on average.

CONCLUSIONS

A centroperipheral IP gradient (∆IP) was monitored during cement delivery in VP. ∆IP decreases with increasing bone cement charge of the vertebra, but C-IP stays significantly higher than P-IP at all times. C-IP was consistently higher than IP values reported for VP so far.

Respiratory effects, hemodynamic changes and cement leakage during multilevel cement balloon kyphoplasty

PURPOSE

The purpose of this study is to evaluate the effects of multilevel balloon kyphoplasty (BK) on blood pressure, blood gases and cement leakage.

METHODS

This is a prospective study of 63 patients: 31 were treated for osteoporotic vertebral compressive fractures (OVCF) and 32 for osteolytic tumors (OT). Twenty-six patients were treated at 1 level, 15 at 2, 2 at 3, 6 at 4, 3 at 5, 4 at 6, 5 at 7 and 2 at 8. PPMA was used in 43 patients and calcium phosphate in 20. All patients were treated under general anesthesia with continuous invasive monitoring of hemodynamic changes, arterial blood gases and peripheral and regional cerebral oxygen saturation.

RESULTS

Two patients had a transient drop in blood pressure between 21 and 42 % during simultaneous inflation of all four balloons at two levels and three more patients during cement injection (two PMMA, one calcium phosphate). Five patients had a cement leak (7.9 %), which was unrelated to the cement type or number of levels. Blood pressure, end-tidal carbon dioxide partial pressure and arterial oxygen partial pressure decreased statistically, but without any clinical significance after cement insertion. Peripheral and regional cerebral oxygen saturation remained unchanged. One-way ANOVA revealed no difference between these changes when clustered by the groups single level, two levels and three or more levels.

CONCLUSION

BK performed under general anesthesia appears to be safe when applied in multiple levels in the same seating provided the balloons are inflated sequentially and not simultaneously and the cement is inserted slowly in a very doughy state. Close monitoring of cardiorespiratory factors is valuable. Its rare circulatory effects are unrelated to the number of levels or the cement type.

Cement leakage in percutaneous vertebroplasty for osteoporotic vertebral compression fractures: identification of risk factors

BACKGROUND CONTEXT

Percutaneous vertebroplasty (PVP) is a common treatment modality for painful osteoporotic vertebral compression fractures (OVCFs). The complication rate of PVP is low, but cement leakage occurs in up to 90% of the treated levels. Recent evidence suggests that sequelae of cement leakage may be more common and clinically relevant than previously thought. Preoperative appreciation of risk factors would therefore be helpful but has not been thoroughly investigated.

PURPOSE

Identification of preoperative risk factors for the occurrence of cement leakage in PVP for painful OVCFs.

STUDY DESIGN

Retrospective assessment of risk factors using multivariate analysis.

PATIENT SAMPLE

Eighty-nine patients treated with PVP for 177 painful OVCFs.

OUTCOME MEASURE

Occurrence of cement leakage.

METHODS

The influence of all known risk factors and other parameters potentially affecting the occurrence of cement leakage was retrospectively assessed using multivariate analysis. Patient age, sex, and spinal deformity index; fracture age, level, type, and semiquantitative severity grade (1-4), the presence of an intravertebral cleft and/or cortical disruption on preoperative magnetic resonance imaging (MRI), and the viscosity of bone cement were included. Cement leakage was assessed on direct postoperative computed tomography scanning of the treated levels. In addition to cement leakage in general, three fundamentally different leakage types (cortical, epidural, and anterior venous), with different possible clinical sequelae, were discerned, and their respective risk factors were assessed.

RESULTS

In 130 of 173 (75.1%) treated OVCFs, cement leakage was detected. Leakage incidence was found to increase approximately linear with advancing severity grade. High fracture semiquantitative severity grade (adjusted per grade relative risk [RR], 1.14; 95% confidence interval [CI], 1.05-1.24; p=.002) and low bone cement viscosity (medium vs. low viscosity: adjusted RR, 0.73; 95% CI, 0.61-0.87; p<.001) were strong risk factors for cement leakage in general. For cortical leakage (in 95% intradiscal leakage), the presence of cortical disruption on MRI (adjusted RR, 1.62; 95% CI, 1.16-2.26; p=.004) and an intravertebral cleft on MRI (adjusted RR, 1.43; 95% CI, 1.07-1.77; p=.017) were identified as additional strong risk factors.

CONCLUSIONS

High fracture severity grade and low viscosity of polymethylmethacrylate bone cement are general, strong, and independent risk factors for cement leakage. Using MRI assessment, cortical disruption and the presence of an intravertrebral cleft were identified as additional strong risk factors regarding cortical (intradiscal) cement leakage, thereby potentiating anticipation.

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.

Kyphoplasty in the treatment of osteoporotic Vertebral Compression Fractures (VCF) : procedure description and analysis of the outcomes in 128 patients

In recent years, the advent of percutaneous techniques in the management of osteoporotic vertebral compression fractures has proven to be a great step forward in the evolution of patients suffering from this pathology.Vertebroplasty, which was developed in 1984 by Galibert and Deramond, presents the disadvantage of leakage of the cementation material and the impossibility to restore spinal deformity. Kyphoplasty has shown to be almost a definite solution to these problems. The description of the technique, its indications, and the outcomes resulting from our series of 200 vertebral fractures in 128 patients are presented in this paper.

A prospective comparative study of kyphoplasty using the Jack vertebral dilator and balloon kyphoplasty for the treatment of osteoporotic vertebral compression fractures

This study prospectively compared the efficacy of kyphoplasty using a Jack vertebral dilator and balloon kyphoplasty to treat osteoporotic compression fractures between T10 and L5. Between 2004 and 2009, two groups of 55 patients each underwent vertebral dilator kyphoplasty and balloon kyphoplasty, respectively. Pain, function, the Cobb angle, and the anterior and middle height of the vertebral body were assessed before and after operation. Leakage of bone cement was recorded. The post-operative change in the Cobb angle was significantly greater in the dilator kyphoplasty group than in the balloon kyphoplasty group (-9.51 degrees (sd 2.56) vs -7.78 degrees (sd 1.19), p < 0.001)). Leakage of cement was less in the dilator kyphoplasty group. No other significant differences were found in the two groups after operation, and both procedures gave equally satisfactory results in terms of all other variables assessed. No serious complications occurred in either group. These findings suggest that vertebral dilator kyphoplasty can facilitate better correction of kyphotic deformity and may ultimately be a safer procedure in reducing leakage of bone cement.

Pulmonary cement embolization after kyphoplasty: a case report and review of the literature

BACKGROUND CONTEXT

Kyphoplasty is performed for the treatment of osteoporotic compression fractures. A theoretical advantage of this technique is the reduced risk of embolization of cement.

STUDY DESIGN/SETTING

Case report of an incidental finding of cement pulmonary embolization after kyphoplasty of an osteoporotic vertebral compression fracture.

METHODS/RESULTS

Here we report a patient who presented with an incidental finding of pulmonary embolization after kyphoplasty and review the relevant literature.

CONCLUSIONS

Patients who present with symptoms of respiratory distress after kyphoplasty should undergo workup for pulmonary embolism. Clinicians may consider routine postoperative chest radiographs after kyphoplasty to screen for embolic disease. Further research is necessary to identify the risk factors and possible long-term sequelae of cement embolization.

Clinical experience using Cortoss for treating vertebral compression fractures with vertebroplasty and kyphoplasty: twenty four-month follow-up

STUDY DESIGN

Forty patients were enrolled in 2 FDA-approved pilot Investigational Device Exemption (IDE) studies using Cortoss for the treatment of vertebral compression fractures (VCF). Twenty patients were treated at 3 centers, using vertebroplasty (VP) and 20 patients were treated at 5 centers, using kyphoplasty (KP).

OBJECTIVE

To assess the feasibility and clinical outcomes using Cortoss to treat osteoporotic VCF.

SUMMARY OF BACKGROUND DATA

Cortoss is an injectable bioactive, self-setting, radiopaque composite shown to stabilize and provide immediate weight bearing support to fractured vertebrae. Cortoss is approved for use in Europe for both screw and vertebral augmentation. METHODS.: Patient assessments were conducted before surgery and after surgery through 24 months using Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and quality-of-life assessment (SF-12) questionnaires. Extravasations were evaluated using radiographs and CT scans.

RESULTS

Immediate pain improvement was seen in VP patients with VAS scores decreasing from 75.7 before surgery to 35.9 at 72 hours. Continued improvement from baseline was seen out to 2 years (average VAS of 48.9). Disability improved with average ODI scores decreasing from 52.2% preoperative to 38.3% at 2 years for VP patients. Immediate pain improvement was also seen in KP patients with VAS scores decreasing from 78.1 before surgery to 42.7 at 72 hours. Continued improvement from baseline was seen out to 2 years (average VAS of 25.4). ODI scores improved from 60.5% preoperative to 34.5% at 2 years for KP patients. Average material volumes injected were 1.85 mL for VP and 4.13 mL for KP. Extravasations from both techniques were minor, anatomically close to the treated vertebrae and asymptomatic. No cardiac irregularities or pulmonary emboli were observed.

CONCLUSION

These studies indicate Cortoss is safe and effective in treating osteoporotic VCF using vertebroplasty or kyphoplasty. Pain relief and restoration of function with Cortoss is comparable to results found in the literature for polymethylmethacrylate.

Staged-injection procedure to prevent cement leakage during vertebroplasty: an in vitro study

BACKGROUND

Epidural leaks or canal intrusion are often found in vertebroplasty, which can lead to several complications. To the best of our knowledge, this is the first report on using two-stage injection procedure in vertebroplasty to reduce cement leakage rate.

MATERIALS AND METHODS

Fifty cadaveric vertebrae (L1-L5) were harvested from 10 osteoporotic lumbar spines. The age of the female donors ranged from 60 to 72 y; the bone mineral density (BMD) of the vertebrae ranged from 0.226 to 0.631 g/cm(2). Polymethylmethacrylate (PMMA) was injected into vertebral bodies by either novel two-stage injection (1 mL cement was injected at first stage and another 4 mL cement was injected at second stage after the cement solidified) or standard conventional injection procedure. After injection, all vertebral bodies (VBs) were checked for cement leakage into spinal canal by vision and fluoroscopy. Cement leakage rates were recorded.

RESULTS

The two-stage injection procedure resulted in a significant decrease in the epidural or canal leakage rate (P = 0.032). In addition, the paravertebral leakage rate was significantly higher in two-stage injection procedure group (48%) than in conventional injection procedure group (16%). However, no significant difference was found for the total cement leakage rate between the two groups.

CONCLUSION

Compared with conventional procedure, the two-stage injection procedure in vertebroplasty decreased incidence of epidural and canal leaks. The first-stage injecting PMMA can be a barrier to the epidural extravasation of cement during vertebroplasty. Further in vivo and clinical researches are needed to evaluate the new procedure.

Postprocedural CT for perivertebral cement leakage in percutaneous vertebroplasty is not necessary--results from VERTOS II

INTRODUCTION

During percutaneous vertebroplasty (PV), perivertebral cement leakage frequently occurs. There is some concern that cement deposits may migrate towards the lungs via the veins during follow-up. We used baseline and follow-up computed tomography (CT) to assess the incidence and extend of late cement migration in a large consecutive patient cohort.

METHODS

VERTOS II is a prospective multicenter randomized controlled trial comparing PV with conservative therapy for osteoporotic vertebral compression fractures (OVCFs). Patients assigned to PV had baseline postprocedural CT scans of the treated vertebral bodies. After a mean follow-up of 22 months, 54 of 78 patients (69%) had follow-up CT. CT scans were analyzed and compared for perivertebral venous, discal, and soft tissue leakage.

RESULTS

Perivertebral cement leakage occurred in 64 of 80 treated vertebrae (80%; 95% CI, 70% to 87%). All patients remained asymptomatic. Perivertebral venous leakage was present in 56 vertebrae (88%), mostly in the anterior external venous plexus (46 of 56, 82%). Discal leakage occurred in 22 of 64 vertebrae (34%) and soft tissue leakage in two of 64 (4%). Mean injected cement volume in vertebrae with leakage was higher (4.5 versus 3.7 cm(3), p = 0.04). Follow-up CT scan showed unchanged perivertebral cement leakages without late cement migration.

CONCLUSION

Perivertebral cement leaks during PV for OVCFs occurred frequently in the VERTOS II trial. Cement leakage occurred more frequently with higher injected volumes. However, all patients remained asymptomatic, and late cement migration during follow-up did not occur. Standard postprocedural CT of the treated vertebral body in PV is not necessary.

Kyphoplasty for patients with multiple myeloma is a safe surgical procedure: results from a large patient cohort

INTRODUCTION

Only in recent years has balloon kyphoplasty gained significance in the treatment of vertebral fractures as an adequate minimally invasive vertebral stabilization technique. Kyphoplasty has also increasingly been used to treat vertebral osteolyses caused by multiple myeloma (MM).

PATIENTS AND METHODS

In our cohort of 76 patients with MM with a total of 190 vertebral fractures treated with kyphoplasty, we performed a 30-day postoperative analysis of cement leakage, neurologic symptoms, pulmonary embolism, and infections.

RESULTS

Painful osteolytic or fractured vertebrae or even imminent vertebral instability caused by osteolyses were seen as indications for kyphoplasty. One case of pulmonary embolism was observed because of cement leakage as the only postoperative complication.

CONCLUSION

By careful interdisciplinary indication setting and a standardized treatment model, kyphoplasty presents a very safe and effective procedure for the treatment of vertebral osteolyses and fractures caused by MM.

Perforation of the right cardiac ventricular wall by polymethylmethacrylate after lumbar kyphoplasty

The authors report the case of a 74-year-old woman who underwent an L-2 vertebral kyphoplasty. The patient experienced delayed postoperative hemodynamic deterioration that may have been caused by embolization of polymethylmethacrylate (PMMA) cement through the right cardiac ventricular wall. Cardiac and pulmonary embolization of bone cement can develop as a complication of vertebral kyphoplasty. Surgeons should be alert to this potentially life-threatening condition when performing this increasingly popular form of spine procedure.

Tumour necrosis factor modulation for treatment of Alzheimer's disease: rationale and current evidence

Tumour necrosis factor (TNF), a key regulator of varied physiological mechanisms in multiple organ systems, is an immune signalling molecule produced by glia, neurons, macrophages and other immune cells. In the brain, among other functions, TNF serves as a gliotransmitter, secreted by glial cells that envelope and surround synapses, which regulates synaptic communication between neurons. The role of TNF as a gliotransmitter may help explain the profound synaptic effects of TNF that have been demonstrated in the hippocampus, in the spinal cord and in a variety of experimental models. Excess TNF is present in the CSF of individuals with Alzheimer's disease (AD), and has been implicated as a mediator of the synaptic dysfunction that is hypothesized to play a central role in the pathogenesis of AD. TNF may also play a role in endothelial and microvascular dysfunction in AD, and in amyloidogenesis and amyloid-induced memory dysfunction in AD. Genetic and epidemiological evidence has implicated increased TNF production as a risk factor for AD. Perispinal administration of etanercept, a potent anti-TNF fusion protein, produced sustained clinical improvement in a 6-month, open-label pilot study in patients with AD ranging from mild to severe. Subsequent case studies have documented rapid clinical improvement following perispinal etanercept in both AD and primary progressive aphasia, providing evidence of rapidly reversible, TNF-dependent, pathophysiological mechanisms in AD and related disorders. Perispinal etanercept for AD merits further study in randomized clinical trials.

The Patterns of Intraosseous Venography before Percutaneous Vertebroplasty for Osteoporotic Compression Fractures

OBJECTIVE

Bone cement leakage is a well-known potential complication of percutaneous vertebroplasty (PVP) in patients with osteoporotic compression fracture. Even though there has been a controversy in the efficacy of antecedent venography to prevent this complication, many authors have performed intraosseous venography before bone cement injection. The goal of this study was to classify the venous drainage patterns of spine before PVP, and compare their patterns at different vertebral levels.

METHODS

The authors retrospectively reviewed 1,042 intraosseous venographic patterns in 321 patients with 574 osteoporotic compression fractures during six-year period in one institution. To classify venogram patterns, we selected simple lateral X-ray of spine taken immediately after injection of the contrast dye. We classified the venography patterns according to contrast leakage pattern and leakage direction as follows; trabecular (TR), trabecular anterior (TA), trabecular posterior (TP), trabecular anterior-posterior (TAP), trabecular lateral (TL), venous anterior(VA), venous posterior (VP), venous anterior-posterior (VAP), soft tissue (ST). Also, we compared venogram patterns according to different spinal levels.

RESULTS

In overall, the most common pattern was TP type accounting for 37.4% (390/1042) of all intraosseous venograms. This is followed by TAP in 21.5%, TR 17.4%, TA 11.6%, TL 5.8%, ST 4.1%, VA 1.2%, VP 0.6%, and VAP 0.4% in descending order of frequency. According to the spinal level, TR and TAP types were most common in thoracic spine (T6-T10), TP type was most common in thoraco-lumbar spine (T11-L2), and TP and TAP types were most common in lumbo-sacral spine (L3-S1). Contrast dye leakage to soft tissue such as psoas muscle or disc were detected in 43 (4.1%) venograms. Direct venous drainage without staining of vertebral body was found in 23 (2.2%) venograms. The 8.3% of thoracic venogram showed direct venous drainage. Thoracic level showed a more tendency of direct venous drainage than other spine levels (p<0.01).

CONCLUSION

The authors propose a new classification system of intraosseous venography during PVP. The trabecular-posterior (TP) type is most common through all spine, and venous-filling (V) type was most frequent in thoracic spine. Further study would be necessary to elucidate the efficacy of this classification system to prevent bone cement leakage during PVP.

Vertebroplasty comparing injectable calcium phosphate cement compared with polymethylmethacrylate in a unique canine vertebral body large defect model

BACKGROUND CONTEXT

Vertebroplasty was developed to mechanically reinforce weakened vertebral bodies. Polymethylmethacrylate (PMMA) bone cement has been most commonly used but carries risks of thermal injury and respiratory and cardiovascular complications. Calcium phosphate (CaP) offers the potential for biological resorption and replacement with new bone, restoring vertebral body mass and height.

PURPOSE

To compare compressive strength, elastic modulus of the adjacent motion segments, and histologic response of vertebral bodies injected with either CaP or PMMA in a canine vertebroplasty model.

STUDY DESIGN

By using a canine vertebroplasty model, two level vertebroplasties were performed at L1 and L3 and studied for 1 month (n=10) and 6 months (n=10). In each canine, one vertebral defect was randomly injected with either CaP cement (BoneSource; Stryker, Freiberg, Germany) or PMMA.

METHODS

Twenty dogs had an iatrogenically created cavitary lesion at two nonadjacent levels injected with either CaP or PMMA. Canines from each group were tested mechanically (n=5) and histologically (n=5). Histology consisted of axial sections of the L1 and L3 vertebral bodies and high-resolution contact radiographs. Sections from each specimen were embedded in plastic without decalcification to study the bone-cement interface. Bone-cement interfaces were compared for evidence of necrosis, fibrosis, foreign body response, cement resorption, and new bone formation between the PMMA and CaP treatments groups. Mechanical compression testing was performed on specimens from the 1-month (n=5) and 6-month (n=5) time periods. The T13 vertebral body was used as an intact control for the destructive compression testing of L1 and L3. Each vertebral body was compressed to 50% of its original height under displacement control at 15 mm/min to simulate a nontraumatic loading situation. Force and displacement data were recorded in real time.

RESULTS

Vertebral sites containing PMMA were characterized by a thin fibrous membrane. PMMA was detected within the trabeculae, vascular channels, and the spinal canal. Unlike PMMA, CaP underwent resorption and remodeling with vascular invasion and bone ingrowth. Woven and lamellar bone was found on the CaP cement surface, within the remodeled material, and on the surrounding trabeculae. Vertebral body compression strength testing revealed no significant difference in vertebral body height and compressive strength between PMMA and CaP. There was a trend for CaP-treated vertebrae to increase in compressive strength from 1 month to 6 months, whereas PMMA decreased compressive strength when compared with adjacent nontreated vertebrae.

CONCLUSION

For both short and intermediate time periods, the injection of CaP cement can be an effective method to treat large vertebral defects. Early results indicate that CaP remodeling might result in the resorption of the majority of the cement with replacement by lamellar bone.

Intravertebral pressure during vertebroplasty and balloon kyphoplasty: an in vitro study

STUDY DESIGN

Intravertebral pressure (IP) measurements were conducted on human cadaveric lumbar spines in a biomechanical study.

OBJECTIVE

To assess the pressure that is generated in the center of the vertebral body during the cement fill in vertebroplasty (VP) and balloon kyphoplasty (BKP).

SUMMARY OF BACKGROUND DATA

High IP during polymethylmethacrylate (PMMA) injection have frequently been raised as a reason for the higher cement leakage rate during VP in contrast to BKP. The IP recorded in the periphery of the vertebral body is much lower than the injection syringe pressure. The pressure ratios in the central region of the vertebrae close to the injection cannula are not known.

METHODS

VP and BKP were performed in 8 lumbar cadaveric spines. A pressure sensor was placed in the center of the vertebral body. In the VP subgroup a total volume of 6 mL of polymethylmethacrylate cement was delivered in 1.5 mL increments. In the BKP subgroup balloon dilation up to a volume of 4 mL was made before cement injection of 6 mL (1.5 mL increments). Room temperature, cement mixing time, and constant volume flow during cement injection were recorded.

RESULTS

During the administration of the first 1.5 mL of bone cement the average IP for VP was 18.5 versus 1.2 kPa for BKP. For the second filling an average pressure of 34.9 kPa (VP) and 3.4 kPa (BKP) was recorded. The average IP during the third injection was 53.0 kPa (VP) and 14.8 kPa (BKP). The pressure of the last 1.5 mL averaged in 56.6 kPa (VP) and 25.5 kPa (BKP).

CONCLUSION

The IP measured during cement augmentation in cadaveric spines was lower in BKP than in VP. In the BKP group a relative increase of the IP was registered at the end state of cement delivery when the cavity was overfilled.

Complications and safety aspects of kyphoplasty for osteoporotic vertebral fractures: a prospective follow-up study in 102 consecutive patients

Background

Kyphoplasty represents an established minimal-invasive method for correction and augmentation of osteoporotic vertebral fractures. Reliable data on perioperative and postoperative complications are lacking in the literature. The present study was designed to evaluate the incidence and patterns of perioperative complications in order to determine the safety of this procedure for patients undergoing kyphoplasty.

Patients and Methods

We prospectively enrolled 102 consecutive patients (82 women and 20 men; mean age 69) with 135 operatively treated fractured vertebrae who underwent a kyphoplasty between January 2004 to June 2006. Clinical and radiological follow-up was performed for up 6 months after surgery.

Results

Preoperative pain levels, as determined by the visual analogous scale (VAS) were 7.5 +/- 1.3. Postoperative pain levels were significantly reduced at day 1 after surgery (VAS 2.3 +/- 2.2) and at 6-month follow-up (VAS 1.4 +/- 0.9). Fresh vertebral fractures at adjacent levels were detected radiographically in 8 patients within 6 months. Two patients had a loss of reduction with subsequent sintering of the operated vertebrae and secondary spinal stenosis. Accidental cement extravasation was detected in 7 patients in the intraoperative radiographs. One patient developed a postoperative infected spondylitis at the operated level, which was treated by anterior corporectomy and 360 degrees fusion. Another patient developed a superficial wound infection which required surgical revision. Postoperative bleeding resulting in a subcutaneous haematoma evacuation was seen in one patient.

Conclusion

The data from the present study imply that percutaneous kyphoplasty can be associated with severe intra- and postoperative complications. This minimal-invasive surgical procedure should therefore be performed exclusively by spine surgeons who have the capability of managing perioperative complications.

Percutaneous vertebroplasty and kyphoplasty for the stand-alone augmentation of osteoporosis-induced vertebral compression fractures: Present status and future directions

Enormous research efforts are being expended on two minimally invasive procedures: percutaneous vertebroplasty (VP) and kyphoplasty (KP). The present report, which is a detailed critical review of VP and KP that emphasizes their biomechanics aspects, is divided into six parts. In the first two parts, succinct descriptions are given of osteoporosis-induced vertebral body (VB) compression fractures as the underlying pathology to be treated with VP and KP, the theory of VP and KP, and the techniques used in performing these procedures. Concerns about VP and KP, such as the high radiation exposure burden that may be imposed on both patient and medical personnel and extravasation of the injectable bone cement, are discussed in the third part. Detailed discussions of fourteen issues/questions, such as the extent to which VP or KP affects various biomechanical measures of the augmented VB and those adjacent to it and the appropriate volume of the cement to use, are presented in the fourth part. Ideas for future research, such as development of a new generation of injectable bone cements and identification of an appropriate animal model, are covered in the fifth part. The final section contains a summary of the most salient points/observations made in the report.

The craniospinal venous system

The valveless craniospinal venous system consists of veins and plexuses that communicate freely and whose flow is bidirectional. It comprises (1) the intracranial-cortical veins, dural sinuses, cavernous sinuses and ophthalmic veins, and (2) the vertebral venous plexuses, which freely anastomose with the intracranial venous system. The vertebral venous plexuses anastamose with the sacral, pelvic and prostatic venous plexus. It is clinically important since it provides a route for the spread of tumours, infection or emboli. This route may go unrecognised.

Current concepts and techniques in percutaneous vertebroplasty

Percutaneous vertebroplasty is a safe and effective alternative for the treatment of many different types of painful vertebral lesions, including osteoporotic compression fractures,hemangiomas, or malignancy-induced pathologic vertebral fractures. Medical therapy often is limited to pain control and immobilization. Because surgery is contraindicated frequently in patients who have osteoporotic compression fractures, and because patients who have widespread metastatic disease often are not surgical candidates, vertebroplasty may be the only practical option. In experienced hands and with appropriately selected patients, percutaneous vertebroplasty is a safe, inexpensive, and highly efficacious procedure; however, because of the potential for devastating complications, all efforts must be made to optimize patient safety.