Vertebroplasty and kyphoplasty for the management of osteoporotic vertebral compression fractures

Robot-assisted spinal augmentation procedures: is it worth the increased effort?

PURPOSE

Spinal augmentation procedures (SAP) are standard procedures for vertebral compression fractures. Often, SAPs are carried out in a minimally invasive, percutaneous way. Certain anatomic conditions such as small pedicles or kyphotic deformities resulting from a significant collapse of the vertebral body might render the operation more difficult and increase the risk of complications. Thus, robot assistance might be useful to optimize the trajectory and to reduce procedure-associated complications. In this study robot-assisted percutaneous SAPs are compared with conventional fluoroscopy-guided percutaneous SAP.

METHODS

A retrospective observational analysis was carried out. Standard demographic parameters were analyzed. Procedural data including radiation dosage records were screened. Biomechanical data were recorded. Cement volumes were analyzed. The precision of the pedicular trajectory was reviewed, and misplaced trajectories were categorized. Procedure-associated complications were analyzed and evaluated for their clinical significance.

RESULTS

A total of 130 procedures were reviewed, and 94 patients were finally included. Osteoporotic fractures (OF) were the main indication (60.7%; OF 2-44%, OF 4-33%). Demographic parameters and clinically relevant complications were equally distributed between the two groups. Duration of surgery was significantly longer in robot-assisted procedures (p < 0.001). Intraoperative radiation exposure was equally distributed. Injected cement volume was similar in both groups. There was no significant difference in pedicle trajectory deviation.

CONCLUSION

The use of robot assistance in SAP seems not to be superior with regard to accuracy, radiation exposure and the rate of complications when compared to fluoroscopy-guided SAP.

Systematic Review and Meta-Analysis of 3 Treatment Arms for Vertebral Compression Fractures: A Comparison of Improvement in Pain, Adjacent-Level Fractures, and Quality of Life Between Vertebroplasty, Kyphoplasty, and Nonoperative Management

BACKGROUND

Osteoporotic vertebral fractures (OVFs) have become increasingly common, and previous nonrandomized and randomized controlled trials (RCTs) have compared the effects of cement augmentation versus nonoperative management on the clinical outcome. This meta-analysis focuses on RCTs and the calculated differences between cement augmentation techniques and nonsurgical management in outcome (e.g., pain reduction, adjacent-level fractures, and quality of life [QOL]).

METHODS

A systematic review was performed according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, and the following scientific search engines were used: MEDLINE, Embase, Cochrane, Web of Science, and Scopus. The inclusion criteria included RCTs that addressed different treatment strategies for OVF. The primary outcome was pain, which was determined by a visual analog scale (VAS) score; the secondary outcomes were the risk of adjacent-level fractures and QOL (as determined by the EuroQol-5 Dimension [EQ-5D] questionnaire, the Oswestry Disability Index [ODI], the Quality of Life Questionnaire of the European Foundation for Osteoporosis [QUALEFFO], and the Roland-Morris Disability Questionnaire [RDQ]). Patients were assigned to 3 groups according to their treatment: vertebroplasty (VP), kyphoplasty (KP), and nonoperative management (NOM). The short-term (weeks), midterm (months), and long-term (>1 year) effects were compared. A random effects model was used to summarize the treatment effect, including I2 for assessing heterogeneity and the revised Cochrane risk-of-bias 2 (RoB 2) tool for assessment of ROB. Funnel plots were used to assess risk of publication bias. The log of the odds ratio (OR) between treatments is reported.

RESULTS

After screening of 1,861 references, 53 underwent full-text analysis and 16 trials (30.2%) were included. Eleven trials (68.8%) compared VP and NOM, 1 (6.3%) compared KP and NOM, and 4 (25.0%) compared KP and VP. Improvement of pain was better by 1.31 points (95% confidence interval [CI], 0.41 to 2.21; p < 0.001) after VP when compared with NOM in short-term follow-up. Pain effects were similar after VP and KP (midterm difference of 0.0 points; 95% CI, -0.25 to 0.25). The risk of adjacent-level fractures was not increased after any treatment (log OR, -0.16; 95% CI, -0.83 to 0.5; NOM vs. VP or KP). QOL did not differ significantly between the VP or KP and NOM groups except in the short term when measured by the RDQ.

CONCLUSIONS

This meta-analysis provides evidence in favor of the surgical treatment of OVFs. Surgery was associated with greater improvement of pain and was unrelated to the development of adjacent-level fractures or QOL. Although improvements in sagittal balance after surgery were poorly documented, surgical treatment may be warranted if pain is a relevant problem.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Paraplegia due to intradural cement leakage after vertebroplasty: a case report and literature review

Background

Vertebroplasty (VP) is considered an alternative therapy in an osteoporotic compression fracture that failed conservative treatment. However, cement leakage into the intradural space can cause catastrophic complications. To the best of our knowledge, intradural cement leakage following VP has been reported only in 7 cases. We report here a case of intradural cement leakage following VP with a literature review.

Case presentation

An 84-year-old female with an L1 osteoporotic fracture underwent percutaneous VP at a local hospital. Immediately after the procedure, she complained of weakness, numbness, and pain in both legs, and her back pain aggravated. She was transferred to our hospital. The initial muscle power was grade 2 for the right leg and grade 4 for the left leg. Computed tomography (CT) scan showed intradural cement leakage from T10 to L2. Magnetic resonance imaging showed an intradural mass lesion. Although we performed total laminectomy with durotomy and removed intradural cement completely, the neurological deficit did not completely recover. The muscle power was grade 3 for the right leg and grade 4 for the left leg at the last follow-up.

Conlcusions

If a neurological deficit is found after VP, a CT scan should be taken to confirm the pattern of cement leakage. In case of intradural cement leakage, surgical decompression should be recommended to improve neurological deficit. To prevent intradural cement leakage during the VP, the needle tip should not perforate the medial wall of the pedicle with appropriate viscosity of cement.

Clinical comparison between a percutaneous hydraulic pressure delivery system and balloon tamp system using high-viscosity cement for the treatment of osteoporotic vertebral compression fractures

OBJECTIVES

Osteoporotic vertebral compression fractures (OVCFs) affect the elderly population, especially postmenopausal women. Percutaneous kyphoplasty is designed to treat painful vertebral compression fractures for which conservative therapy has been unsuccessful. High-viscosity cement can be injected by either a hydraulic pressure delivery system (HPDS) or a balloon tamp system (BTS). Therefore, the purpose of this study was to compare the safety and clinical outcomes of these two systems.

METHODS

A random, multicenter, prospective study was performed. Clinical and radiological assessments were carried out, including assessments of general surgery information, visual analog scale, quality of life, cement leakage, and height and angle restoration.

RESULTS

Using either the HPDS or BTS to inject high-viscosity cement effectively relieved pain and improved the patients' quality of life immediately, and these effects lasted at least two years. The HPDS using high-viscosity cement reduced cost, surgery time, and radiation exposure and showed similar clinical results to those of the BTS. In addition, the leakage rate and the incidence of adjacent vertebral fractures after the HPDS treatment were reduced compared with those after treatment using the classic vertebroplasty devices. However, the BTS had better height and angle restoration abilities.

CONCLUSIONS

The percutaneous HPDS with high-viscosity cement has similar clinical outcomes to those of traditional procedures in the treatment of vertebral fractures in the elderly. The HPDS with high-viscosity cement is better than the BTS in the treatment of mild and moderate OVCFs and could be an alternative method for the treatment of severe OVCFs.

Percutaneous Vertebral Augmentation Techniques in Osteoporotic and Traumatic Fractures

Percutaneous vertebral augmentation/consolidation techniques are varied. These are vertebroplasty, kyphoplasty, and several methods with percutaneous introduction of an implant (associated or not with cement injection). They are proposed in painful osteoporotic vertebral fractures and traumatic fractures. The objectives are to consolidate the fracture and, if possible, to restore the height of the vertebral body to reduce vertebral and regional kyphosis. Stabilization of the fracture leads to a reduction in pain and thus restores the spinal support function as quickly as possible, which is particularly important in the elderly. The effectiveness of these interventions on fracture pain was challenged once by two randomized trials comparing vertebroplasty to a sham intervention. Since then, many other randomized studies in support of vertebroplasty efficacy have been published. International recommendations reserve vertebroplasty for medical treatment failures on pain, but earlier positioning may be debatable if the objective is to limit kyphotic deformity or even reexpand the vertebral body. Recent data suggest that in osteoporotic fracture, the degree of kyphosis reduction achieved by kyphoplasty and percutaneous implant techniques, compared with vertebroplasty, is not sufficient to justify the additional cost and the use of a somewhat longer and traumatic procedure. In young patients with acute traumatic fractures and a significant kyphotic angle, kyphoplasty and percutaneous implant techniques are preferred to vertebroplasty, as in these cases a deformity reduction has a significant positive impact on the clinical outcome.

Bone cement distribution is a potential predictor to the reconstructive effects of unilateral percutaneous kyphoplasty in OVCFs: a retrospective study

Background

Osteoporotic vertebral compression fracture (OVCF) is a common type of fracture, and percutaneous kyphoplasty (PKP) is an eligible solution to it. Previous studies have revealed that both the volume and filling pattern of bone cement correlate with the clinical outcomes after PKP procedure. However, the role of bone cement distribution remains to be illustrated.

Methods

To retrospectively evaluate the relationship between the bone cement distribution and the clinical outcomes of unilateral PKP, we enrolled 73 OVCF patients receiving unilateral PKP treatment. All the intervened vertebrae were classified into three groups based on the bone cement distribution observed on postoperative X-ray films. Preoperative and postoperative radiographic parameters including the vertebral height and kyphotic Cobb angle were recorded, and anterior vertebral height restoration rate (AVHRR) and Cobb angle correction (CR) were then calculated to assess the vertebral height reconstruction. Preoperative and postoperative Oswestry Disability Index (ODI) and visual analogue scale (VAS) were adopted by interviewing patients to assess the mobility improvement and pain relief. Demographic data, body mass index (BMI), lumbar bone mineral density (evaluated by BMD T-score) of each patient, bone cement volume (BV), and bone cement extravasation (BE) were also recorded. Between- and within-group comparisons and multivariable correlation analysis were carried out to analyze the data.

Results

VAS and ODI scores were both significantly improved in all of the enrolled cases with no significant differences between groups. Among the three groups, the average age, AVHRR, and BV were significantly different. Occurrence of BE was significantly different between two of the three groups. AVHRR was demonstrated to correlate negatively with preoperative anterior vertebral height ratio and positively with preoperative Cobb angle, CR, diffusion score, and ODI changes.

Conclusions

Bone cement distribution is a potential predictor to the reconstructive effects in unilateral PKP for OVCFs. Bone cement distribution is associated with AVHRR and BV, as well as the risk of BE occurrence. Greater bone cement distribution may indicate better vertebral restoration along with a higher BE risk.

Increased sagittal vertical axis is associated with less effective control of acute pain following vertebroplasty

OBJECTIVES

Although vertebroplasty is very effective for relieving acute pain from an osteoporotic vertebral compression fracture, not all patients who undergo vertebroplasty receive the same degree of benefit from the procedure. In order to identify the ideal candidate for vertebroplasty, pre-operative prognostic demographic or clinico-radiological factors need to be identified. The objective of this study was to identify the pre-operative prognostic factors related to the effect of vertebroplasty on acute pain control using a cohort of surgically and non-surgically managed patients.

PATIENTS AND METHODS

Patients with single-level acute osteoporotic vertebral compression fracture at thoracolumbar junction (T10 to L2) were followed. If the patients were not satisfied with acute pain reduction after a three-week conservative treatment, vertebroplasty was recommended. Pain assessment was carried out at the time of diagnosis, as well as three, four, six, and 12 weeks after the diagnosis. The effect of vertebroplasty, compared with conservative treatment, on back pain (visual analogue score, VAS) was analysed with the use of analysis-of-covariance models that adjusted for pre-operative VAS scores.

RESULTS

A total of 342 patients finished the 12-week follow-up, and 120 patients underwent vertebroplasty (35.1%). The effect of vertebroplasty over conservative treatment was significant regardless of age, body mass index, medical comorbidity, previous fracture, pain duration, bone mineral density, degree of vertebral body compression, and canal encroachment. However, the effect of vertebroplasty was not significant at all time points in patients with increased sagittal vertical axis.

CONCLUSIONS

For single-level acute osteoporotic vertebral compression fractures, the effect of vertebroplasty was less favourable in patients with increased sagittal vertical axis (> 5 cm) possible due to aggravation of kyphotic stress from walking imbalance.Cite this article: Y-C. Kim, D. H. Bok, H-G. Chang, S. W. Kim, M. S. Park, J. K. Oh, J. Kim, T-H. Kim. Increased sagittal vertical axis is associated with less effective control of acute pain following vertebroplasty. Bone Joint Res 2016;5:544-551. DOI: 10.1302/2046-3758.511.BJR-2016-0135.R1.

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.

Balloon kyphoplasty in patients with osteoporotic vertebral compression fractures

Balloon kyphoplasty (BKP) is a minimally invasive surgical procedure indicated for treatment of painful vertebral compression fractures. During BKP, cannulae are placed percutaneously into the vertebral body, allowing insertion of inflatable balloons. Inflating the balloons partially restores vertebral body height, compacts the bone and creates a cavity for placement of bone cement after balloon removal. Placement of the cement reduces and stabilizes the fracture. BKP differs from vertebroplasty in that it aims to restore vertebral height and reduce kyphotic deformity. Case reports and observational studies have consistently shown that BKP significantly reduces pain, increases mobility and functional capacity and improves quality of life for up to 3 years. Clinically significant adverse events have been rarely reported. These findings were confirmed in randomized and nonrandomized prospective controlled studies. The objective of this review is to describe the surgical procedures involved in BKP and to review the evidence supporting its use.

Comparison of unipedicular and bipedicular balloon kyphoplasty for the treatment of osteoporotic vertebral compression fractures

This is a prospective randomised study comparing the clinical and radiological outcomes of uni- and bipedicular balloon kyphoplasty for the treatment of osteoporotic vertebral compression fractures. A total of 44 patients were randomised to undergo either uni- or bipedicular balloon kyphoplasty. Self-reported clinical assessment using the Oswestry Disability Index, the Roland-Morris Disability questionnaire and a visual analogue score for pain was undertaken pre-operatively, and at three and twelve months post-operatively. The vertebral height and kyphotic angle were measured from pre- and post-operative radiographs. Total operating time and the incidence of cement leakage was recorded for each group.

Both uni- and bipedicular kyphoplasty groups showed significant within-group improvements in all clinical outcomes at three months and twelve months after surgery. However, there were no significant differences between the groups in all clinical and radiological outcomes. Operating time was longer in the bipedicular group (p < 0.001). The incidence of cement leakage was not significantly different in the two groups (p = 0.09).

A unipedicular technique yielded similar clinical and radiological outcomes as bipedicular balloon kyphoplasty, while reducing the length of the operation. We therefore encourage the use of a unipedicular approach as the preferred surgical technique for the treatment of osteoporotic vertebral compression fractures.

Cite this article: Bone Joint J 2013;95-B:401–6.

Kyphoplasty for the Treatment of Very Severe Osteoporotic Vertebral Compression Fracture

Objective:

A retrospective evaluation of the clinical outcome and technical feasibility of kyphoplasty for the treatment of very severe osteoporotic vertebral compression fracture (vsOVCF).

Methods:

Patients with vsOVCF were treated with kyphoplasty and followed-up for 1 year. Vertebral body height variation, kyphotic angle, back pain (visual analogue scale [VAS]) and Oswestry disability index (ODI) were evaluated preoperatively, postoperatively, 1 month, 3 months and 1 year after treatment.

Results:

In total, 35 patients (49 vertebrae) were treated with kyphoplasty. There were no cases of spinal or extraspinal injury, infection, bleeding, pulmonary embolism, epidural cement leakage, stroke or cardiac arrest as a result of treatment. There were significant postoperative improvements in all outcome measures (vertebral body height variation, kyphotic angle, VAS and ODI); these improvements were maintained during the follow-up period.

Conclusion:

Kyphoplasty is an effective and minimally invasive procedure for the treatment of vsOVCF.

FINITE ELEMENT ANALYSIS OF A MODEL OF SIMULATED VERTEBRAL CEMENT AUGMENTATION: INFLUENCE OF THE REPRESENTATION OF THE SHAPE OF THE CEMENT DOMAIN ON BIOMECHANICAL PARAMETERS

Vertebral cement augmentation is rapidly becoming the modality of choice for treating patients who are experiencing severe and persistent pain because of osteoporosis-induced vertebral compression fracture(s). The resulting cement domain (the part of the vertebral body (VB) filled with the cement) has an irregular or complicated shape. In literature reports of finite element analysis (FEA) of models of simulated vertebral cement augmentation, a variety of representations of the shape of the cement domain have been used. In the literature, only very limited attention has been given to the issue of the influence of cement domain shape representation on biomechanical parameters for a given combination of model and loading. This issue is the subject of the present work, with the model being of the L1-L3 motion segments. Augmentation of an unfractured L2 (prophylactic augmentation) was simulated, three cement domain shapes were considered — namely, solid cylinder, with rounded edges; two prolate spheroids; and oblate spheroid — and the applied loading comprised a simultaneous application of a uniform compressive pressure of 0.53 MPa (equivalent to an 800-N compression load) and a counter-clockwise-acting axial rotation moment of 1 Nm to the superior surface of L1. It was found that (1) while the cement domain shape representation has a marked influence on the mean von Mises stress (σAVM), the maximum von Mises stress (σMVM), and the strain energy density (MSED) distribution in the cement domain, its influence on each of these parameters in each of the biological tissues in the model as well as on the total segmental range of motion is minimal and (2) for σAVM and σMVM, the lowest value of each of these parameters was obtained when the oblate spheroid model was used. From both clinical and computational perspectives, these findings are significant. For example, the latter finding suggests that there is scope for researching the combination of key process variables used, such as the cement chemistry, the cement delivery system, and the augmentation technique/approach, that would ensure that the final cement domain shape in cement-augmented VBs of patients be oblate spheroid on a consistent and predictable basis.

Renal osteodystrophy: neurosurgical considerations and challenges

BACKGROUND

Dialysis-associated destructive spondyloarthropathy (DSA) is the major bony complication of end-stage renal disease, most commonly found in the lower cervical region. The risk factors for developing dialysis-associated DSA include duration of hemodialysis and patient age. Patients with DSA have a higher incidence of osteoporosis and poor bone mineral density, which may place them at greater risk of atraumatic fractures, instrumentation failure, and neurologic compromise.

METHODS

We describe a case of cervical radiculopathy due to dialysis-associated DSA atraumatic vertebral body fractures with a postoperative course that was complicated by instrumentation failure. We reviewed the literature regarding all 138 published cases, presenting the complications, surgical treatment options, and outcomes.

RESULTS

A 44-year-old dialysis-dependent man presented with acute neck pain, radiculopathy, and weakness due to atraumatic fracture of C5 and C6 vertebral bodies. He underwent anterior C5 and C6 corpectomies, reconstruction with mesh cage and plate, and supplemental posterior instrumentation (C4-T1). Six weeks later, a computed tomography scan revealed anterior translation across the instrumented area with failure of the posterior instrumentation. He subsequently underwent traction, revision reinstrumentation from C2 to T5, and placement of external halo ring/jacket for 6 months. At 18 months later, he remains ambulatory without evidence of construct failure.

CONCLUSIONS

Patients with renal osteodystrophy present a challenge for the spine surgeon due to compromised bone density. Hardware failure at the bone-construct interface is common in these patients, with revision surgery needed in 22% of published cases. Longer constructs with circumferential instrumentation and halo immobilization may minimize the risk of pseudoarthrosis and construct pull-out.

A comparative analysis of the results of vertebroplasty and kyphoplasty in osteoporotic vertebral compression fractures

BACKGROUND

The most common complication of osteoporosis is vertebral fractures, which occur more frequently than all other fractures (hip, wrist, and ankle).

OBJECTIVE

To prospectively analyze vertebroplasty compared with kyphoplasty for the treatment of osteoporotic vertebral compression fractures using improvement in pain, functional capacity, and quality of life as outcome measures.

METHODS

The study population included 28 patients in the vertebroplasty group and 24 patients in the kyphoplasty group. The mean follow-up period was 42.2 weeks and 42.3 weeks in the vertebroplasty and kyphoplasty groups, respectively. Outcomes were measured pre- and postoperatively using the visual analogue scale, the Oswestry Disability Index, the EuroQol-5D questionnaire, and the Short-Form 36 Health Survey.

RESULTS

In the vertebroplasty group, visual analogue scale scores improved from a mean of 8.0 cm to 5.5 cm at last follow-up (P = .001). Preoperatively, the Oswestry Disability Index was 57.6, which improved to 38.4 (P = .006). The EuroQol-5D score preoperatively was 0.157 and improved to 0.504 (P = .001). The Short-Form 36 Health Survey showed greatest improvement in the areas of physical health, role physical, body pain, and vitality. In the kyphoplasty group, visual analogue scale scores improved from a mean of 7.5 cm preoperatively to 2.5 cm postoperatively (P = .000001). The mean Oswestry Disability Index preoperatively was 50.7 and improved to 28.8 (P = .002). The EuroQol-5D score improved from a mean of 0.234 preoperatively to 0.749 (P = .00004). The Short-Form 36 Health Survey showed greatest improvement in the areas of physical health, physical functioning, role physical, body pain, and social functioning.

CONCLUSION

Both vertebroplasty and kyphoplasty are effective at improving pain, functional disability, and quality of life; however, kyphoplasty provides better results, which are maintained over long-term follow-up.

Epidural cement leakage through pedicle violation after balloon kyphoplasty causing paraparesis in osteoporotic vertebral compression fractures - a report of two cases

Kyphoplasty is advantageous over vertebroplasty in terms of better kyphosis correction and diminished risk of cement extravasations. Literature described cement leakage causing neurological injury mainly after vertebroplasty procedure; only a few case reports show cement leakage with kyphoplasty without neurological injury or proper cause of leakage. We present a report two cases of osteoporotic vertebral compression fracture treated with kyphoplasty and developed cement leakage causing significant neurological injury. In both cases CT scan was the diagnostic tool to identify cause of cement leakage. CT scan exhibited violation of medial pedicle wall causing cement leakage in the spinal canal. Both patients displayed clinical improvement after decompression surgery with or without instrumentation. Retrospectively looking at stored fluoroscopic images, we found that improper position of trocar in AP and lateral view simultaneously while taking entry caused pedicle wall violation. We suggest not to cross medial pedicle wall in AP image throughout the entire procedure and keeping the trocar in the center of pedicle in lateral image would be the most important precaution to prevent such complication. Our case reports adds the neurological complications with kyphoplasty procedure and suggested that along with other precautions described in the literature, entry with trocar along the entire procedure keeping the oval shape of pedicle in mind (under C-arm) will probably help to prevent such complications.

[Transpedicular osteotomy with dorsal wedge osteotomy: treatment of post-traumatic or postinfection kyphotic malalignment of the thoraco-lumbar spine]

BACKGROUND

The purpose of the study was to evaluate the clinical and radiological follow-up of patients suffering from fixed post-traumatic and postinflammatory kyphotic deformities of the thoracic and lumbar spine and treated by posterior transpedicular wedge resection osteotomy of the spine.

METHODS

A total of 28 patients received a posterior transpedicular wedge resection osteotomy. A prospective follow-up was performed preoperatively, postoperatively and after 3, 6 and 12 months. The kyphotic angle of the fractured segment was evaluated as well as the clinical parameters the self-reported visual analog scale (VAS) and the Oswestry score.

RESULTS

The median pain scores (VAS) and the Oswestry disability scores (p<0.05) decreased significantly from pretreatment to post-treatment. Postoperatively a significant correction of the kyphotic angle could be achieved with a mean of 28 degrees (range 14-44 degrees ). In the follow-up after 1 year there was a 7 degrees increase in kyphosis.

CONCLUSIONS

Transpedicular wedge resection osteotomy of the thoracic and lumbar spine offers a safe surgical technique for the treatment of fixed postinflammatory kyphotic deformities.

Vertebral body innervation: Implications for pain

Vertebral fractures often cause intractable pain. To define the involvement of vertebral body innervation in pain, we collected specimens from male and female patients during percutaneous kyphoplasty, a procedure used for reconstruction of the vertebral body. Specimens were taken from 31 patients (9 men and 22 women) suffering high-intensity pain before surgery. In total, 1,876 histological preparations were obtained and analysed. Immunohistochemical techniques were used to locate the nerves in the specimens. The nerve fibres were labelled by indirect immunofluorescence with the primary antibody directed against Protein Gene Product 9.5 (PGP 9.5), a pan-neuronal marker; another primary antibody directed against type IV collagen (Col IV) was used to identify vessels and to determine their relationship with vertebral nerve fibres. The mean percentage of samples in which it was possible to identify nerve fibres was 35% in men and 29% in women. The percentages varied depending on the spinal level considered and the sex of the subject, nerve fibres being mostly present around vessels (95%). In conclusion, there is scarce innervation of the vertebral bodies, with a clear prevalence of fibres located around vessels. It seems unlikely that this pattern of vertebral body innervation is involved in vertebral pain or in pain relief following kyphoplasty.

Evaluation of two novel aluminum-free, zinc-based glass polyalkenoate cements as alternatives to PMMA bone cement for use in vertebroplasty and balloon kyphoplasty

Vertebroplasty (VP) and balloon kyphoplasty (BKP) are now widely used for treating patients in whom the pain due to vertebral compression fractures is severe and has proved to be refractory to conservative treatment. These procedures involve percutaneous delivery of a bolus of an injectable bone cement either directly to the fractured vertebral body, VB (VP) or to a void created in it by an inflatable bone tamp (BKP). Thus, the cement is a vital component of both procedures. In the vast majority of VPs and BKPs, a poly(methyl methacrylate) (PMMA) bone cement is used. This material has many shortcomings, notably lack of bioactivity and very limited resorbability. Thus, there is room for alternative cements. We report here on two variants of a novel, bioactive, Al-free, Zn-based glass polyalkenoate cement (Zn-GPC), and how their properties compare to those of an injectable PMMA bone cement (SIMPL) that is widely used in VP and BKP. The properties determined were injectability, radiopacity, uniaxial compressive strength, and biaxial flexural modulus. In addition, we compared the compression fatigue lives of a validated synthetic osteoporotic VB model (a polyurethane foam cube with an 8 mm-diameter through-thickness cylindrical hole), at 0-2300 N and 3 Hz, when the hole was filled with each of the three cements. A critical review of the results suggests that the performance of each of the Zn-GPCs is comparable to that of SIMPL; thus, the former cements merit further study with a view to being alternatives to an injectable PMMA cement for use in VP and BKP.

Clinical experience with high-viscosity cements for percutaneous vertebral body augmentation: occurrence, degree, and location of cement leakage compared with kyphoplasty

BACKGROUND AND PURPOSE

Vertebroplasty is known for its high leakage rate compared with kyphoplasty. In recent preclinical studies, high-viscosity cements were shown to significantly enhance the uniformity of cement filling and decrease the incidence of leakage in cancellous bonelike substrates compared with low-viscosity cements. In this study, the incidence and pattern of cement leakage by using a new high-viscosity cement (Confidence spinal cement system) was compared with that of standard kyphoplasty.

MATERIALS AND METHODS

Postoperative radiographs of patients treated with either kyphoplasty or Confidence were analyzed for cement leakage by using a stringent and thorough 4-point scale (none, minimal, moderate, or severe). When leakage was observed, the location of the cement leakage was also recorded and described as diskal, venous, paravertebral, or epidural. Sixty-two consecutive patients with 112 treated levels were included in this retrospective review. There were 46 kyphoplasty- versus 66 Confidence-treated levels, which ranged from T3 to L5.

RESULTS

The average vertebral collapse reached 27.9 +/- 20.7% in the Confidence group versus 25.0 +/- 19.1% in the kyphoplasty group. There was no or mild leakage in 92% of Confidence and 91% of the kyphoplasty cases (mild, 39% Confidence versus 50% kyphoplasty). Severe leakage was only reported in 1 (2%) Confidence and 1 (2%) kyphoplasty case. In both cases, the severe leakage was found in the disk space. No significant leakage that required any surgical intervention was noticed.

CONCLUSIONS

This finding confirms prior observations that highly viscous cements may increase the safety of vertebral augmentation techniques compared with less viscous cements. The high-viscosity Confidence cement results in a leakage rate comparable with that of kyphoplasty.

Influence of powder-to-liquid monomer ratio on properties of an injectable iodine-containing acrylic bone cement for vertebroplasty and balloon kyphoplasty

The interventional radiological techniques of vertebroplasty (VP) and balloon kyphoplasty (BKP) are widely used in cases where the pain secondary to compression fractures of vertebral bodies is severe, persistent, and refractory to conservative treatments. In the majority of VP and BKP cases, an injectable poly(methyl methacrylate) (PMMA) bone cement and different values of powder-to-liquid monomer ratio (PLMR) are used. A systematic study of the influence of PLMR on relevant cement properties is lacking. This was the subject of the present study, with the injectable PMMA bone cement used being an experimental one whose radiopacity is provided by an iodine-containing compound in the powder. The PLMRs used-1.54, 2.22, and 3.08 g mL(-1)-are within the range used in clinical reports on VP and BKP. One property of the curing cement, namely, the polymerization rate at 37 degrees C (k'), was estimated using nonisothermal differential scanning calorimetry results. The fatigue lives (N(f)) of cured cement specimens were obtained under axial loading corresponding to axial stresses (S) of +/-20.0, 15.0, 12.5, and 10.0 MPa, at a frequency of 2 Hz. The fatigue limit of the cement was estimated from the fit of the S - N(f) results to the Olgive equation. With increase in PLMR, k' increased significantly, but the influence of PLMR on the fatigue limit and on another property also estimated from the S - ln N(f) results is not significant.

Clinical relevance of pain patterns in osteoporotic vertebral compression fractures

Few studies have been conducted to explain the pain patterns resulting from osteoporotic vertebral compression fractures (OVCF). We analyzed pain patterns to elucidate the pain mechanism and to provide initial guide for the management of OVCFs. Sixty-four patients underwent percutaneous vertebroplasty (N=55) or kyphoplasty (N=9). Three pain patterns were formulized to classify pains due to OVCFs: midline paravertebral (Type A), diffuse paravertebral (Type B), and remote lumbosacral pains (Type C). The degree of compression was measured using scale of deformity index, kyphosis rate, and kyphosis angle. Numerical rating scores were serially measured to determine the postoperative outcomes. As vertebral body height (VBH) decreased, paravertebral pain became more enlarged and extended anteriorly (p<0.05). Type A and B patterns significantly showed the reverse relationship with deformity index (p<0.05), yet Type C pattern was not affected by deformity index. Postoperative pain severity was significantly improved (p<0.05), and patients with a limited pain distribution showed a more favorable outcome (p<0.05). The improvement was closely related with the restoration of VBH, but not with kyphosis rate or angle. Thus, pain pattern study is useful not only as a guide in decision making for the management of patients with OVCF, but also in predicting the treatment outcome.