In vivo temperature profile of intervertebral discs and vertebral endplates during vertebroplasty: an experimental study in sheep

Percutaneous Fixation with Internal Cemented Screws for Iliac Lytic Bone Metastases: Assessment of Pain and Quality of Life on Long Term Follow-up

PURPOSE

To assess effectiveness on pain, quality of life and late adverse events of percutaneous fixation with internal cemented screw (FICS) among patients with iliac lytic bone metastases with or without pathological fractures.

MATERIALS AND METHODS

This retrospective exploratory study analyzed FICS procedures on iliac osteolytic bone lesions with and without pathological fracture performed from July 2019 to January 2022 in one tertiary level university hospital. The procedure were performed under general anesthesia, and were CT and fluoroscopically guided. Numerical Pain Rate Score (NPRS), mean EuroQol visual analogue scale (EQ VAS), morphine consumption, walking ability, walking perimeter and presence of walking aids and the appearance of complications were evaluated.

RESULTS

Nineteen procedures among 18 patients were carried out with a mean follow up time of 243.3 ± 243.2 days. The mean of the maximum NPRS decreased from 8.4 ± 1.3 to 2.2 ± 3.1 at 1 month (p < 0.01) and remained between 1.3 and 4.1 during a follow-up consultation period of 3-24 months. The mean EQ VAS rose from 42.0 ± 12.5 to 57.3 ± 13.9 at 1 month (p < 0.01) follow-up and remained between 55.8 and 62.5 thereafter. No patient scores returned to pre-procedure levels during follow-up. Mean morphine use decreased from 111.1 ± 118.1 to 57.8 ± 70.3 mg/d at 1 month (p > 0.05) follow-up. No late adverse events were reported.

CONCLUSION

Percutaneous FICS is a safe procedure with fast and long-standing effect on pain, mobility and quality of life. It can be used as a complement to the known analgesic therapeutic arsenal for bone metastases.

Quantitative Comparison of Vertebral Structural Changes After Percutaneous Vertebroplasty Between Unilateral Extrapedicular Approach and Bilateral Transpedicular Approach Using Voxel-Based Morphometry

OBJECTIVE

To compare unilateral extrapedicular vertebroplasty (UEV) and bilateral transpedicular vertebroplasty (BTV) by quantitatively calculating the structural changes of fractured vertebral body after percutaneous vertebroplasty (PVP) using 3-dimensional voxel-based morphometry (VBM).

METHODS

We calculated bone cement volume (BCV); vertebral body volume (VBV); leaked intradiscal BCV; and spatial, symmetric, and even bone cement distribution (BCD) in and out of 222 vertebral bodies treated with 2 different PVPs using VBM and evaluated the incidence of subsequent vertebral compression fracture (SVCF). Statistical analyses were conducted to compare values between the 2 different PVPs.

RESULTS

Relative BCV, which is a potential risk factor for SVCF, was higher in the BTV group based on the data using VBM (0.22±0.03 vs. 0.29±0.03; p<0.001, t-test); however, the SVCF incidence between the 2 surgeries was not significantly different (UEV, 24.7%; BTV, 31%; p=0.046, chi-square test). Spatial, even, and symmetric BCD along the 3 axes was not significantly different between UEV and BTV using VBM (x, y, z-axis, p=0.893, p= 0.590, p=0.908 respectively, chi-square test).

CONCLUSION

Contrary to intuitive concerns, UEV can inject a sufficient and more optimal BCV than BTV. Additionally, it can inject bone cement spatially, symmetrically, and evenly well-distributed without an increased rate of intradiscal leakage and SVCF compared with BTV based on VBM. Therefore, UEV could be a superior alternative surgical method with similar clinical effectiveness and safety, considering the above results and the consensus that UEV is less invasive.

Effect of Percutaneous Kyphoplasty on the progression of intervertebral disc degeneration: a retrospective cohort study

BACKGROUND

The effect of percutaneous kyphoplasty (PKP) or rather polymethylmethacrylate (PMMA) on adjacent intervertebral discs is still controversial. The evidence from experimental study to clinical study presents bipolar conclusions. In this study, we investigated the effect of PKP on adjacent intervertebral disc degeneration (IDD).

METHODS

The experimental group included adjacent intervertebral discs of vertebrae treated with the PKP procedure, and the control group included adjacent intervertebral discs of non-traumatized vertebrae. All measurements were taken by magnetic resonance imaging or X-ray. The intervertebral disc height, the modified Pfirrmann grading system (MPGS), and its differences with Klezl Z and Patel S (ZK and SP) classifications were compared.

RESULTS

A total of 264 intervertebral discs from 66 individuals were selected for the study. The comparison of intervertebral disc height between the two groups pre and post-operatively resulted in a p-value of > 0.05. No significant change was observed in the adjacent discs in the control groups post-operatively. Post-operatively, the mean Ridit increased significantly from 0.413 to 0.587 in the upper disc and from 0.404 to 0.595 in the lower disc in the experimental group. The comparison of MPGS differences showed that the predominant value was 0 in the Low-grade leaks group and 1 in the Medium and high-grade leaks group.

CONCLUSIONS

The PKP procedure can accelerate adjacent IDD, but it does not cause disc height changes in the early stage. The quantity of cement leaking into the disc space positively correlated with the rate of disc degeneration progression.

Translation of a spinal bone cement product from bench to bedside

Spinal acrylic bone cements (ABCs) are used clinically for percutaneous vertebroplasty (PVP) and kyphoplasty (PKP) to treat osteoporotic vertebral compression fractures. Product translation of spinal ABC products followed the design control processes including design verification and validation. The bench to bedside translation of the first Chinese spinal ABC product (Alliment®, namely Alliment Cement) approved by National Medical Products Administration of China was investigated and another commercial product served as the control (Osteopal®V, namely Osteopal V Cement). Results of non-clinical bench performance verification tests of compression, bending and monomer release showed that the newly marketed Alliment Cement is similar to the Osteopal V Cement with properties of both meeting the criteria specified by standards. The Alliment Cement demonstrated good biocompatibility during the 26 weeks’ bone implantation test. Porcine cadaver validation tests further revealed that the Alliment Cement satisfied the needs for both PVP and PKP procedures. A post-approval, retrospective clinical investigation further demonstrated the safety and efficacy of the Alliment Cement, with a significant reduction of pain and the improved stability of the fractured vertebral bodies. A successful translation of biomaterial medical products needs close collaborations among academia, industry, healthcare professionals and regulatory agencies.

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Bench-to-bedside research of the first Chinese spinal acrylic bone cement product.

•Pre- & clinical investigations demonstrate the product's safety and efficacy.

•Translation of biomaterial medical products follows regulated processes.

Cement Augmented Anterior Reconstruction and Decompression without Posterior Instrumentation: A Less Invasive Surgical Option for Osteoporotic Thoracolumbar Fracture with Cord Compression

Objective

We investigated the clinical and radiological outcomes of a cement augmented anterior reconstruction and decompression without pedicle screw fixation in patients with osteoporotic thoracolumbar vertebral fracture with myelopathy.

Methods

There were 2 male and 6 female patients with thoracolumbar fracture and myelopathy included in the study. The mean follow-up period was more than 1 years. The anterolateral decompression and cement augmented anterior reconstruction with poly(methyl methacrylate) (PMMA) was performed. Demographic data, clinical outcomes, perioperative parameters and radiologic parameter were retrospectively evaluated.

Results

The symptoms due to myelopathy were improved in all patients. The preoperative median visual analog scale score for lower back and leg were 8.5 that improved 4.25 and 3 at last follow up. The preoperative function state showed a median Oswestry Disability Index score 61.5 that improved 33. After surgery, preoperative encroachment of the spinal canal (5.12 mm, 37%) was disappeared. The median height of fractured vertebral body significantly increased from 7.83 to 12.63 mm. At the last follow-up point, the median height was 9.91 mm. The median kyphotic deformity was improved from 22.12° to 14.31°. At the final follow-up, the improvement was preserved (median value: 15.03). The acute complication according to PMMA such as leakage and embolization was none, but adjacent compression fracture as late complication according to cement augmentation was. One patient developed surgical site infection.

Conclusion

On the basis of the preliminary results, we considered that anterolateral decompression and PMMA augmentation might be an optimal method for treating osteoporotic fracture with myelopathy in elderly patients or those with multiple medical comorbidities.

Effects of Mobilization Time on Occurrence of New Fractures after Vertebroplasty

Introduction

Osteoporotic vertebral fracture treatment options include vertebroplasty, in which development of new fractures is among the possible complications which may develop during the postoperative period. We aim to evaluate whether or not postoperative mobilization time has effect on occurrence of new fractures.

Materials and Methods

A total of 126 patients, consisting of 30 (39.7%) males and 96 (60.3%) females, who underwent sedation-assisted vertebroplasty under local anesthesia between January 2014 and June 2017 were retrospectively evaluated. Preoperative and postoperative visual analogue scores (VASs) and mobilization time (hours) were assessed. Day of new fracture occurrence during follow-up was assessed.

Results

The mean follow-up period was 9 months (7–13 months). The most common fracture segment was the L1 vertebra (15.9%). The preoperative VAS was 8.29 ± 0.95, and the postoperative VAS was 2.33 ± 0.91. The change in VAS was statistically significant (p=0.01, p < 0.05). Of all the patients, 21 (16.66%) had developed new fractures. No statistical difference was observed between mobilization time (hours) and formation of new fractures (p=0.48, p > 0.05).

Conclusion

We came to the conclusion that mobilization time (hours) was not a risk factor in the development of new fractures. In addition, there is no relationship between mobilization time and localization of new fractures.

Inhibition of both endplate nutritional pathways results in intervertebral disc degeneration in a goat model

Background

The vertebral endplate route was demonstrated to be the main pathway for nutrition to the intervertebral disc. However, it is still a controversial issue on whether the blocking of the endplate nutritional pathway could result in intervertebral disc degeneration (IDD) in animal models. The aim was therefore to investigate the effect of the inhibition of both endplate nutritional pathways by bone cement injection on the IDD in a goat model.

Methods

Two lumbar intervertebral discs (L2–3 and L3–4) in eight 24-month-old goats were blocked in both endplate nutritional pathways by cement injection, and the other two lumbar intervertebral discs (L1–2 and L4–5) remained intact as normal controls. Effective blocking area percentage in nucleus pulposus (NP) was calculated, and X-rays, magnetic resonance imaging (MRI), and histology studies were performed at 4, 12, 24, and 48 weeks after operation.

Results

The mean effective blocking area percentage was 60.7 ± 5.3%. Imaging examinations at the time of 48 weeks after blocking the endplate nutritional pathways showed obvious IDD, with larger disc height reduction and higher degrees of disc degeneration grading compared with the normal controls. Histological examinations including HE, Masson’s trichrome, Sirius Red, and proteoglycan stainings also confirmed the degenerative changes of the blocked discs.

Conclusions

The endplate nutritional route could be inhibited by blocking both endplate pathways with cement injection in a goat model. The severe inhibition in the endplate nutritional pathways may result in IDD.

Image-Guided Bone Consolidation in Oncology

Occurrence of bone metastases is a common event in oncology. Bone metastases are associated with pain, functional impairment, and fractures, particularly when weight-bearing bones are involved. Management of bone metastases has been improved by the development of various interventional radiology consolidation techniques. Cementoplasty is based on injection of acrylic cement into a weakened bone to reinforce it and to control pain. This minimally invasive technique has proven its efficacy for flat bone submitted to compression forces. However, resistance to torsion forces is limited and, thus, treatment of long bones should be considered with caution. In recent years, variant techniques of percutaneous bone consolidation have emerged, including expansion devices for vertebral augmentation and percutaneous screw fixation for pelvic bone and proximal femur tumors. Research projects are ongoing to develop drug-loaded cements to use them as therapeutic vectors. However, release of drugs is still poorly controlled and conventional polymethylmethacrylate cement remains the gold standard in oncology. Image-guided consolidation techniques enhance the array of treatments in bone oncology. Multidisciplinary approach is mandatory to select the best indications.

[Image-guided bone consolidation in oncology: Cementoplasty and percutaneous screw fixation]

Bone metastases are a common finding in oncology. They often induce pain but also fractures which impair quality of life, especially when involving weight-bearing bones. Percutaneous image-guided consolidation techniques play a major role for the management of bone metastases. Cementoplasty aims to stabilize bone and control pain by injecting acrylic cement into a weakened bone. This minimally invasive technique has proven its efficacy for bones submitted to compression forces: vertebra, acetabular roof, and condyles. However, long bone diaphysis should be treated with caution due to lower resistance of the cement subject to torsional forces. The recent improvements of navigation systems allow percutaneous image-guided screw fixation without requiring open surgery. This fast-track procedure avoids postponing introduction of systemic therapies. If needed, cementoplasty can be combined with screw insertion to ensure better anchoring in major osteolysis. Interventional radiology bone consolidation techniques increase the therapeutic field in oncology. A multidisciplinary approach remains mandatory to select the best indications.

Osseous vitality in single photon emission computed tomography/computed tomography (SPECT/CT) after balloon tibioplasty of the tibial plateau: a case series

Background

The minimally invasive, balloon-assisted reduction and cement-augmented internal fixation of the tibial plateau is an innovative surgical procedure for tibial plateau fractures. The close proximity of balloons and cement to the knee joint poses a potential risk for osteonecrosis; especially in the case of thin bone lamellae. However, there are no studies about the vitality of the cement-surrounding tissue after these tibioplasties. Therefore, our goal was to assess the osseous vitality after cement-augmented balloon tibioplasty using single photon emission computed tomography/computed tomography (SPECT/CT) in a series of patients.

Methods

This case series evaluated available consecutive patients, whose tibial plateau fractures were treated with balloon-assisted, cement-augmented tibioplasty and received a SPECT/CT. Primary outcome variables were osseous vitality on SPECT/CTs according to the semiquantitative tracer activity analysis. The mean uptake of eight tibial regions of interest was referenced to the mean uptake count on the same region of the contralateral leg to obtain a count ratio. Osteonecrosis was defined as a photopenic area or cold defect. Secondary variables included clinical and radiological follow-up data. Statistics were carried out in a descriptive pattern.

Results

Ten patients with a mean age of 59 years and a mean follow up of 18 months were included. Calcium phosphate (CaP) substitute bone cement was used in 60 % and polymethyl methacrylate mixed with hydroxyapatite (PMMA/HA) bone cement in 40 %. Normal to high SPECT/CT activity without photopenic areas were observed in all patients and the mean tracer activity ratio was four, indicating vital bone in all patients. There were no postoperative infections and only one 57 year old patient with hemineglect and CaP cement showed failed osseous consolidation. The mean Tegner and Lysholm as well as the Lysholm scores were three and 80, respectively.

Conclusions

This novel study about cement-augmented balloon tibioplasties showed that osseous vitality remains intact according to SPECT/CT analysis; irrespective of the type of cement and even in the presence of thin bone lamellae. This procedure was safe and well-suited for lateral tibial plateau fractures in particular. Surgeons may consider using PMMA/HA bone cement for void filling in elderly fracture patients without concern about bone viability.

Current trends in mini-invasive management of spine metastases

The spine is a frequent localization of primary tumours or metastasis involving posterior arch, pedicles and vertebra body, and often causing unsustainable pain. The management of spinal metastasis remains complex, including medical therapy (corticosteroids, chemotherapy), radiotherapy and surgical treatment, or the recent percutaneous mini-invasive approach. The target of all these treatments is to improve the quality of life of patients affected by this type of lesion. Diagnosis of spinal metastasis and then its treatment should be based on the combination of different elements: clinical evaluation, CT, MRI and nuclear medicine patterns, considering the age of the patient, known primary tumour, location of the lesions, single/multiple lesions, pattern of morphology (border, matrix, expansile character, soft tissue extension), density or signal intensity, oncologic instability and expectancy of life. The percutaneous mini-invasive approach for patients affected by secondary lesions involving the spine has as treatment goal of: (1) pain relief improving the quality of life; (2) stability treatment re-establishing the spinal biomechanics, alterated by bone destruction or deformity, preventing pathological fracture; and (3) an anti-neoplastic effect. The aim of this paper is to provide a comprehensive diagnostic and percutaneous approach to the bone metastatic spine lesions, identifying which metamer should be treated to improve patient quality of life, showing the importance of a multi-disciplinary approach to this problem.

Cement augmentation in vertebral burst fractures

As a result of axial compression, traumatic vertebral burst fractures disrupt the anterior column, leading to segmental instability and cord compression. In situations with diminished anterior column support, pedicle screw fixation alone may lead to delayed kyphosis, nonunion, and hardware failure. Vertebroplasty and kyphoplasty (balloon-assisted vertebroplasty) have been used in an effort to provide anterior column support in traumatic burst fractures. Cited advantages are providing immediate stability, improving pain, and reducing hardware malfunction. When used in isolation or in combination with posterior instrumentation, these techniques theoretically allow for improved fracture reduction and maintenance of spinal alignment while avoiding the complications and morbidity of anterior approaches. Complications associated with cement use (leakage, systemic effects) are similar to those seen in the treatment of osteoporotic compression fractures; however, extreme caution must be used in fractures with a disrupted posterior wall.

Establishing a rabbit spinal tumor model for nonvascular interventional therapy through CT-guided percutaneous puncture inoculation

BACKGROUND AND PURPOSE

An animal spinal tumor model is needed to better simulate the clinical situation and to allow percutaneous puncture, which may provide an experimental platform for the new nonvascular interventional therapies. We established a rabbit spinal tumor model through a CT-guided percutaneous puncture inoculation technique for nonvascular interventional therapy.

MATERIALS AND METHODS

VX2 tumor cells were inoculated into the lumbar vertebrae of 32 rabbits through a CT-guided percutaneous puncture technique; then, the development of hind limb paraparesis was observed in the rabbits twice a day. MR imaging and CT were performed on days 14, 21, and 28 postinoculation and at the development of hind limb paraparesis. On days 21 and 28 postinoculation, 2 rabbits, whose imaging suggested successful modeling without hind limb paraparesis, were chosen on each day. The lumbar vertebrae were sampled from 1 rabbit for histopathologic examination, and the other rabbit underwent PET-CT examination before percutaneous vertebroplasty. Finally the lesion vertebrae were sampled for histopathologic examination.

RESULTS

The success rate of modeling was 90.6% (29/32) in our study. On day 21 postinoculation, successful modeling was achieved in 21 rabbits, with 19 having no hind limb paraparesis. On day 28 postinoculation, another 7 achieved successful modeling, and only 1 developed hind limb paraparesis. Percutaneous vertebroplasty treatment was successful for the 2 rabbit models.

CONCLUSIONS

Establishment of a rabbit spinal tumor model through a CT-guided percutaneous puncture technique and inoculation of VX2 tumor is easy and has a high success rate. The established model can be used to study nonvascular interventional therapies for spinal tumor, including percutaneous vertebroplasty.

Effects of bone cement on intervertebral disc degeneration

Percutaneous vertebroplasty (PVP) is popular for the treatment of intractable pain due to vertebral collapse from various lesions, intervertebral disk leakage of cement is a frequent complication. The aim of this study was to determine whether bone cement causes disc degeneration, and to evaluate the degree of intervertebral disc degeneration (IDD) according to the time period following cement injection, and the type and volume of cement injected. Sixteen dogs were randomly divided into two groups that were sacrificed at 12 or 24 weeks following cement injection. Five intervertebral discs in each dog were studied, including one control untreated disc and four discs randomly injected with polymethylmethacrylate (PMMA) or calcium phosphate cement (CPC) in two quantities. Radiographic and magnetic resonance imaging (MRI) studies were performed prior to animal sacrifice. T2-weighted mid-sagittal images of the discs were qualitatively analyzed for evidence of degeneration by calculating the MRI index, and all harvested discs were studied histopathologically. IDD was not evident in control discs. Univariate analysis revealed significant differences in the MRI index and the histological grade of disc degeneration in terms of the time period following cement injection, as well as the type and volume of cement injected. Result indicate that direct contact with PMMA and CPC can lead to IDD. However, IDD induced by PMMA was more severe than that induced by CPC. The extent of IDD was found to correlate with the time period post-cement injection and the volume of cement injected into the disc. PMMA and CPC may lead to intervertebral disc degeneration. Intervertebral disc degeneration induced by PMMA is more serious than that of CPC. The degree of intervertebral disc degeneration is correlative to the time after operation and the doses of bone cement.

Intraoperative PEEP-ventilation during PMMA-injection for augmented pedicle screws: improvement of leakage rate in spinal surgery

BACKGROUND

Within the last two decades the use of polymethylmethacrylate (PMMA) in the treatment of osteoporotic vertebral fractures has been established widely. Several techniques of cement application in spinal surgery have been described. Besides classical vertebroplasty, kyphoplasty and related techniques that reinforce stability of the fractured vertebral body itself, augmentation of pedicle screws became an issue in the past 10 years. Aim of this technique is strengthening of the implant-bone-interface and the prevention of loosening and failure of posterior instrumentation in limited bone quality due to osteoporosis. PMMA use in spinal surgery always bears the risk of cement leakage and cement embolism. There are only few publications dealing with cement leakage in pedicle screw augmentation. We examined our cohort concerning incidence and type of leakage in comparison to the literature. In particular, we evaluated a possible role of intrathoracic pressure during cementation procedure.

PATIENTS AND METHODS

In this retrospective study 42 patients were included. Mean age was 74 (57-89) years. 311 fenestrated, augmented screws were analyzed postoperatively concerning leakage and subsequent pulmonary embolism of cement particles. Overall, there was a leakage rate of 38.3 %, and 28.6 % of patients showed pulmonary embolism of PMMA. During surgery, patients were in part ventilated with a positive end-expiratory pressure (PEEP) of 15 cmH2O during cement injection. These individuals showed significantly less leakage locally as well as less PMMA-emboli in the pulmonary circulation in contrast to patients ventilated without increased PEEP.

CONCLUSION

PEEP elevation during administration of PMMA via fenestrated pedicle screws is reducing the leakage rate in spinal surgery. These beneficial effects warrant further evaluation in prospective studies.

Hypothermic manipulation of bone cement can extend the handling time during vertebroplasty

Background

Polymethylmethacrylate (PMMA) is commonly used for clinical applications. However, the short handling time increases the probability of a surgeon missing the crucial period in which the cement maintains its ideal viscosity for a successful injection. The aim of this article was to illustrate the effects a reduction in temperature would have on the cement handling time during percutaneous vertebroplasty.

Methods

The injectability of bone cement was assessed using a cement compressor. By twisting the compressor, the piston transmits its axial load to the plunger, which then pumps the bone cement out. The experiments were categorized based on the different types of hypothermic manipulation that were used. In group I (room temperature, sham group), the syringes were kept at 22°C after mixing the bone cement. In group 2 (precooling the bone cement and the container), the PMMA powder and liquid, as well as the beaker, spatula, and syringe, were stored in the refrigerator (4°C) overnight before mixing. In group 3 (ice bath cooling), the syringes were immediately submerged in ice water after mixing the bone cement at room temperature.

Results

The average liquid time, paste time, and handling time were 5.1 ± 0.7, 3.4 ± 0.3, and 8.5 ± 0.8 min, respectively, for group 1; 9.4 ± 1.1, 5.8 ± 0.5, and 15.2 ± 1.2 min, respectively, for group 2; and 83.8 ± 5.2, 28.8 ± 6.9, and 112.5 ± 11.3 min, respectively, for group 3. The liquid and paste times could be increased through different cooling methods. In addition, the liquid time (i.e. waiting time) for ice bath cooling was longer than for that of the precooling method (p < 0.05).

Conclusions

Both precooling (i.e. lowering the initial temperature) and ice bath cooling (i.e. lowering the surrounding temperature) can effectively slow polymerization. Precooling is easy for clinical applications, while ice bath cooling might be more suitable for multiple-level vertebroplasty. Clinicians can take advantage of the improved injectability without any increased cost.

Osteoporotic vertebral compression fracture augmentation by injectable partly resorbable ceramic bone substitute (Cerament™|SPINESUPPORT): a prospective nonrandomized study

INTRODUCTION

This study aimed to evaluate long-term stabilizing healing effectiveness and influence on adjacent intact vertebral bodies of a new injectable partly resorbable calcium sulfate (60 wt.%)/hydroxyapatite (40 wt.%) bone substitute employed in vertebral augmentation of osteoporotic collapses.

METHODS

From April 2009 to April 2011, 80 patients underwent vertebral augmentation. Patient enrolment criteria are as follows: age more than 20 years; symptomatic osteoporotic vertebral compression fracture from low energy trauma encompassing level T5 to L1 and classified as A1.1 to A1.2 according to the AO classification system; vertebral height compression within 0-75% compared to the posterior (dorsal) wall; client history confirming the age of the compression fracture to be within at least 4 weeks; and patients who are able to understand the procedure and participate in the study. Preoperative and postoperative imaging studies consisted of computed tomography, plain X-ray, dual X-ray absorptiometry scanning, and magnetic resonance. Pain intensity has been evaluated by an 11-point visual analog scale (VAS), and physical and quality of life compromise assessments have been evaluated by Oswestry Disability Questionnaire (ODI). All procedures have been performed fluoroscopically guided by left unilateral approach under local anesthesia and mild sedation.

RESULTS

VAS-based pain trend over 12-month follow-up has shown a statistical significant (p < 0.001) decrease, starting from 7.68 (SD 1.83) preoperatively with an immediate first day decrease at 3.51 (SD 2.16) and 0.96 (SD 0.93) at 12 months. The ODI score dropped significantly from 54.78% to 20.12% at 6 months. None device-related complication has been reported. In no case, a new incidental adjacent fracture has been reported.

CONCLUSION

Data show how this injectable partly resorbable ceramic cement could be a nontoxic and lower stiffness alternative to polymethylmethacrylate for immediate and long-term stabilization of osteoporotic collapsed vertebral bodies.

Complication of cemented vertebra after kyphoplasty in osteoporotic compression fracture

The reported case is of a postmenopausal woman with kyphoplasty for an L1 osteoporotic compression fractures (OCF) presenting with progressive kyphosis and paraparesis that developed with no history of other traumas. Serial radiographs and computed tomography were performed, followed by magnetic resonance (MR) imaging. On serial radiographs, local kyphosis and neurologic deficit progressed with collapse of the cemented vertebra. MR scan and histologic examination diagnosed avascular necrosis (AVN). The symptoms resolved after posterior vertebral column resection of the collapsed cemented vertebral body and correction of the deformity. Although kyphoplasty is a simple and safe procedure for the management of pain in OCFs, careful follow-up is required as collapse of the cemented vertebra may be an AVN of the cemented vertebra and lead to neurologic deficit over time.

Heat distribution of polymerisation temperature of bone cement on the spinal canal during vertebroplasty

PURPOSE

In the last 15 years, vertebroplasty and kyphoplasty have become established operative procedures for treating osteoporotic vertebral-body fractures and vertebral bodies afflicted with metastases. These procedures are quickly performed with few personnel and material resources and have a low rate of complications. However, cases of neurological impairment are reported in the scientific literature. We analysed whether potentially harmful heat is radiated/conducted by the polymerisation temperature of polymethylmethacrylate (PMMA) bone cement in the spinal canal.

METHODS

We performed vertebroplasty on 25 vertebral bodies and measured the temperature distribution during polymerisation of bone cement within the spinal canal using heat probes placed in the respective areas. The vertebral bodies were located in a circulating water bath at 37°C.

RESULTS

During polymerisation of the bone cement, a temperature rise was measured. The peak temperature was reached after few minutes. Temperature curves differed; a maximum temperature of up to 43.16°C was detected for a few seconds only.

CONCLUSION

When vertebroplasty is performed correctly, there is no temperature development that could eventually damage the spinal cord or spinal nerves.

Percutaneous bone tumor management

Interventional radiology plays a major role in the management of bone tumors. Many different percutaneous techniques are available. Some aim to treat pain and consolidate a pathological bone (cementoplasty); others aim to ablate tumor or reduce its volume (sclerotherapy, thermal ablation). In this article, image-guided techniques of primary and secondary bone tumors with vertebroplasty, ethanol injection, radiofrequency ablation, laser photocoagulation, cryoablation, and radiofrequency ionization (coblation) will be reviewed. For each modality, the principles, the indications, and the results will be presented. The technical choice depends on the therapeutic intent-curative or palliative-and the need for consolidation, but also on the general status of the patient and the other therapeutic options. For the most complex cases, combined treatments can be required. However, the less disabling technique should always be considered first.

Cement leakage causes potential thermal injury in vertebroplasty

BACKGROUND

Percutaneous vertebroplasty by injecting PMMA bone cement into the fractured vertebrae has been widely accepted in treatment of spinal compression fracture. However, the exothermic polymerization of bone cement may cause osseous or neural tissue injury. This study is thus designed to evaluate the potential risk of thermal damage in percutaneous vertebroplasty.

METHOD

Twelve porcine vertebrae were immersed in 37°C saline for the experiment. In the first stage of the study, vertebroplasty without cement leakage (control group, n = 6) was simulated. The anterior cortex, foramen, posterior cortex and the center of the vertebral body were selected for temperature measurement. Parameters including peak temperature and duration above 45°C were recorded. In the second stage, a model (n = 6) simulating bone cement leaking into the spinal canal was designed. The methods for temperature measurement were identical to those used in the first stage.

RESULTS

In Stage 1 of the study (vertebroplasty of the porcine vertebral body in the absence of cement leakage), the average maximal temperature at the anterior cortex was 42.4 ± 2.2°C; at the neural foramen 39.5 ± 2.1°C; at the posterior cortex 40.0 ± 2.5°C and at the vertebral center, 68.1 ± 3.4°C. The average time interval above 45°C was 0 seconds at the anterior cortex; at the neural foramen, 0 seconds; at the posterior cortex, 0 seconds and at the vertebral center, 223 seconds. Thus, except at the core of the bone cement, temperatures around the vertebral body did not exceed 45°C. In Stage 2 of the study (cement leakage model), the average maximal temperature at the anterior cortex was 42.7 ± 2.4°C; at the neural foramen, 41.1 ± 0.4°C; at the posterior cortex, 59.1 ± 7.6°C and at the vertebral center, 77.3 ± 5.7°C. The average time interval above 45°C at the anterior cortex was 0 seconds; at the neural foramen, 0 seconds; at the posterior cortex, 329.3 seconds and at the vertebral center, 393.2 seconds. Based on these results, temperatures exceeded 45°C at the posterior cortex and at the vertebral center.

CONCLUSIONS

The results indicated that, for bone cement confined within the vertebra, curing temperatures do not directly cause thermal injury to the nearby soft tissue. If bone cement leaks into the spinal canal, the exothermic reaction at the posterior cortex might result in thermal injury to the neural tissue.

Diagnosis and management of metastatic spine disease. A review

With continued growth of the elderly population and improvements in cancer therapies, the number of patients with symptomatic spinal metastases is likely to increase, and this is a condition that commonly leads to debilitating neurological dysfunction and pain. Advancements in surgical techniques of resection and spinal reconstruction, improvements in clinical outcomes following various treatment modalities, generally increased overall survival in patients with metastatic spine disease, and a recent randomized trial by Patchell and colleagues demonstrating the superiority of a combined surgical/radiotherapeutic approach over a radiotherapy-only strategy have led many to suggest increasingly aggressive interventions for patients with such lesions. Optimal management of spinal metastases encompasses numerous medical specialties, including neurosurgery, orthopedic surgery, medical and radiation oncology, radiology, and rehabilitation medicine. In this review, the clinical presentation, diagnosis, and management of spinal metastatic disease are discussed. Ultimately, the goal of treatment in patients with spinal metastases remains palliative, and clinical judgment is required to select the appropriate patients for surgical intervention.

Percutaneous cement augmentation for the treatment of depression fractures of the tibial plateau

The management of insufficiency fractures of the tibial plateau in osteoporotic patients can be very challenging, since it is difficult to achieve a stable fixation, an essential condition for the patients' early mobilization. We present a minimally invasive technique for the treatment of proximal tibial plateau fractures, "tibiaplasty", using percutaneous polymethylmethacrylate augmentation. Five osteoporotic patients (7 fractures) with a non-traumatic insufficiency tibial plateau fracture were treated with this technique at the authors' institution from 2006 to 2008. The patients' median age was 79 (range 62-88) years. The intervention was performed percutaneously under general or spinal anesthesia; after the intervention, immediate full weight bearing was allowed. The technique was feasible in all patients and no complications related to the intervention were observed. All patients reported a relevant reduction in pain, were able to mobilize with full weight bearing and would undergo the operation again. No secondary loss of reduction or progression of arthrosis was observed in radiological controls; no revision surgery was required. Our initial results indicate that tibiaplasty is a good treatment option for the management of insufficiency in tibial plateau fractures in osteoporotic patients. The technique is minimally invasive, safe and allows immediate mobilization without restrictions. In our group of patients, we found excellent early to mid-term results.

Long-term evaluation of a calcium phosphate bone cement with carboxymethyl cellulose in a vertebral defect model

We investigated histological and compressive properties of a calcium phosphate bone cement (BoneSource (CPC); Stryker Orthopaedics, Mahwah, New Jersey) plus carboxymethyl cellulose (CMC) using a sheep vertebral bone void model. Bone voids were surgically created in L3 and L5 in each of 40 sheep, and the voids were filled with the cement. Histological and radiographic evaluations were performed on one vertebral body from each animal at either: 0, 3, 6, 12, 24, or 36 months after surgery; mechanical testing was performed on operated and non-operated vertebral bodies from 35 sheep. Undecalcified sections were digitized, and the area of the original defect, new bone formation, empty space, fibrous tissue, and residual cement were quantified with histomorphometry. Decalcified sections were evaluated qualitatively. The cement was biocompatible, extremely osteoconductive and underwent steady resorption and replacement by bone and bone marrow. Histomorphometry showed variations in the rate of cement remodeling among animals in each time group, but on average, at 36 months the original defect area was occupied by approximately 14% bone, 82% cement, and 4% bone marrow. Even in animals that had greater resorption of cement, there was good bone ingrowth with no fibrous tissue. Compressive testing did not reveal a significant difference in the mechanical properties between vertebral bodies augmented with cement and non-augmented controls, irrespective of the postoperative time. BoneSource mixed with CMC had adequate osteoconductivity, biocompatibility, and adequate compressive strength. There was variability among animals, but histology suggests that considerable cement was still present in most samples after 36 months.

Solitary vertebral metastasis

As survival time increases for many cancers, it is likely that the incidence and prevalence of spinal metastases will increase also. Given that most patients first present with solitary lesions in the spine, proper initial diagnosis and management are of paramount importance in minimizing pain, improving neurologic function, and potentially lengthening survival. Although pain control and standard radiation are still used, spinal stereotactic radiosurgery, vertebroplasty and kyphoplasty, and spinal cord decompression and fusion are now consistently used in aggressive management and offer exciting preliminary results.

Calcium-phosphate and polymethylmethacrylate cement in long-term outcome after kyphoplasty of painful osteoporotic vertebral fractures

STUDY DESIGN

A comparative prospective trial evaluating 3-year outcome.

OBJECTIVE

To compare clinical and morphologic outcomes as well as follow-up fractures after kyphoplasty of painful osteoporotic vertebral fractures with calcium-phosphate (CaP) cement (group 1) and with polymethylmethacrylate (PMMA)-cement (group 2).

SUMMARY OF BACKGROUND DATA

CaP cements seem to be an alternative material for usage in kyphoplasty of vertebral fractures. CaP cements are biodegradable and replaceable by newly formed bone after implantation. Concerns have been raised with regard to the stability of resorbable CaP-cements after implantation into vertebrae post kyphoplasty. Calcibon is a possible CaP cement, which exhibited adequate stability in short-term observations.

MATERIALS AND METHODS

Kyphoplasty was performed in 40 consecutive patients with primary osteoporosis and painful vertebral fractures, 20 received CaP-cement, 20 were treated with PMMA-cement. All patients received a pharmacological antiosteoporosis treatment (1000 mg calcium, 1000 IU vitamin D3, and oral aminobisphosphonate), pain medication, and physiotherapy. Pain (visual analog scale [VAS]; range, 0-100), mobility (EVOS-score; range, 0-100) and radiomorphologic measurements were assessed at baseline and after 6, 12, and 36 months.

RESULTS

There were no statistically significant differences between the CaP and PMMA-cement group regarding VAS-scores, EVOS-scores, or height-restoration at any time point. Furthermore, there was no significant difference in the occurrence of vertebral follow-up fractures between both groups during the 3-year follow-up period.

CONCLUSION

CaP cement, e.g., Calcibon, is as effective and safe as conventional PMMA-cement with regard to immediate and sustained pain reduction and improvement of mobility after kyphoplasty of patients with painful osteoporotic vertebral fractures. CaP cement has the potential of being resorbed and replaced by newly formed bone tissue; thus, it seems to be a promising alternative for PMMA also in younger patients with painful vertebral fractures.

Diagnosis and management of metastatic spine disease

Spinal metastases are a significant source of morbidity in patients with systemic cancer. Roughly 30% of patients with cancer develop symptomatic spinal metastases during the course of their illness, and up to 90% of cancer patients possess metastatic lesions within the spine at the time of death with advances in the treatment of systemic disease, survival in such patients has increased. This factor combined with improved imaging modalities will undoubtedly increase the incidence in which spinal metastases are encountered by physicians. In this review, the authors not only attempt to present the myriad ways in which patient with spinal metastases present, but also the means by which they are currently diagnosed and managed. In addition, we propose a simple algorithm to aid in deciding which patients are ideally treated medically and which patients may benefit from surgery.