Vertebral augmentation with spinal implants: third-generation vertebroplasty.

This article is to review the different types of vertebral augmentation implants recently becoming available for the treatment of benign and malignant spinal compression fractures. After a detailed description of the augmentation implants, we review the available clinical data. We will conclude with a summary of the advantages and disadvantages of vertebral implants and how they can affect the future treatment options of compression fractures.

Spine Intervention-An Update on Injectable Biomaterials.

Back pain is the second most common reason for primary-care physician visits after the common cold. New understanding of the spine pathophysiology and biomechanics led to the development of novel injectable biomaterials to treat those pain generators. Although not all biomaterials are currently ready for common use, there is significant interest by the medical community to invest time, resources, and energy to optimize these injectables.

Multimodal analysis of in vivo resorbable CaP bone substitutes by combining histology, SEM, and microcomputed tomography data.

This study introduced and demonstrated a new method to investigate the repair process of bone defects using micro- and macroporous beta-tricalcium phosphate (β-TCP) substitutes. Specifically, the new method combined and aligned histology, SEM, and preimplantation microcomputed tomography (mCT) data to accurately characterize tissue phases found in biopsies, and thus better understand the bone repair process. The results included (a) the exact fraction of ceramic remnants (CR); (b) the fraction of ceramic resorbed and substituted by bone (CSB); and (c) the fraction of ceramic resorbed and not substituted by bone (CNSB).

A novel method for segmenting and aligning the pre- and post-implantation scaffolds of resorbable calcium-phosphate bone substitutes.

Unlabelled: Micro-computed tomography (microCT) is commonly used to characterize the three-dimensional structure of bone graft scaffolds before and after implantation in order to assess changes occurring during implantation. The accurate processing of the microCT datasets of explanted β-tricalcium phosphate (β-TCP) scaffolds poses significant challenges because of (a) the overlap in the grey values distribution of ceramic remnants, bone, and soft tissue, and of (b) the resorption of the bone substitute during the implantation. To address those challenges, this article introduces and rigorously validates a new processing technique to accurately distinguish these three phases found in the explanted β-TCP scaffolds.

Percutaneous Dorsal Instrumentation of Vertebral Burst Fractures: Value of Additional Percutaneous Intravertebral Reposition-Cadaver Study.

Purpose: The treatment of vertebral burst fractures is still controversial. The aim of the study is to evaluate the purpose of additional percutaneous intravertebral reduction when combined with dorsal instrumentation.

Methods: In this biomechanical cadaver study twenty-eight spine segments (T11-L3) were used (male donors, mean age 64.

Height restoration and maintenance after treating unstable osteoporotic vertebral compression fractures by cement augmentation is dependent on the cement volume used.

Background: Two different procedures, used for percutaneous augmentation of vertebral compression fractures were compared, with respect to height restoration and maintenance after cyclic loading. Additionally the impact of the cement volume used was investigated.

Methods: Wedge compression fractures were created in 36 human cadavaric vertebrae (T10-L3).

Synthesis of spherical calcium phosphate particles for dental and orthopedic applications.

Calcium phosphate materials have been used increasingly in the past 40 years as bone graft substitutes in the dental and orthopedic fields. Accordingly, numerous fabrication methods have been proposed and used. However, the controlled production of spherical calcium phosphate particles remains a challenge.

Vertebral augmentation with nitinol endoprosthesis: clinical experience in 40 patients with 1-year follow-up.

Purpose: This study was designed to assess the clinical outcomes of patients treated by vertebral augmentation with nitinol endoprosthesis (VNE) to treat painful vertebral compression fractures.

Methods: Forty patients with one or more painful osteoporotic VCF, confirmed by MRI and accompanied by back-pain unresponsive to a minimum 2 months of conservative medical treatment, underwent VNE at 42 levels. Preoperative and postoperative pain measured with Visual Analog Scale (VAS), disability measured by Oswestry Disability Index (ODI), and vertebral height restoration (measured with 2-dimensional reconstruction CT) were compared at last follow-up (average follow-up 15 months).

Cement interdigitation and bone-cement interface after augmenting fractured vertebrae: A cadaveric study.

Background: The treatment of painful osteoporotic vertebral compression fractures with transpedicular cement augmentation has grown significantly over the last 20 years. There is still uncertainty about long-term and midterm effects of polymethyl methacrylate in trabecular bone. Preservation of the trabecular structures, as well as interdigitation of the cement with the surrounding bone, therefore has been gaining increasing attention.

Evaluation of the ultrasonication process for injectability of hydraulic calcium phosphate pastes.

This study examined the use of ultrasonication to improve the injectability of an aqueous calcium phosphate paste. Ultrasonication was applied to the paste through the plunger of the delivery syringe. A factorial design of experiments with three investigated factors, liquid to powder ratio (LPR) (38%, 39% and 40%), the size of the delivery syringe (5 and 10 ml) and the amplitude of the 20 kHz power ultrasonication (0-30 μm), was used in this study.

Simulation of the in vivo resorption rate of β-tricalcium phosphate bone graft substitutes implanted in a sheep model.

A few years ago, a model was proposed to predict the effect of the pore architecture of a bone graft substitute on its cell-mediated resorption rate. The aim of the present study was to compare the predictions of the model with the in vivo resorption rate of four β-tricalcium phosphate bone graft substitutes implanted in a sheep model. The simulation algorithm contained two main steps: (1) detection of the pores that could be accessed by blood vessels of 50 μm in diameter, and (2) removal of one solid layer at the surface of these pores.

Mechanical variables affecting balloon kyphoplasty outcome--a finite element study.

It is still unclear how a vertebral fracture should be stabilised and strengthened without endangering the remaining intact bone of the augmented vertebra or the adjacent vertebrae. Numerical modelling may provide insight. To date, however, few finite element (FE) spine models have been developed which are both multi-segmental and capture a more complete anatomy of the vertebrae.

Cement filling control and bone marrow removal in vertebral body augmentation by unipedicular aspiration technique: an experimental study using leakage model.

Study Design: Experimental design using a laboratory leakage model.

Objective: To examine that a new aspiration technique, with a double conduit cannula design, improves the uniformity of cement filling, thus significantly reducing the risk of extraosseous leakage.

Summary Of Background Data: In vertebral augmentation, understanding the forces governing the intravertebral cement flow is essential for controlling the cement formation.

Cement leakage and filling pattern study of low viscous vertebroplastic versus high viscous confidence cement.

Background: Vertebral augmentation has recently evolved as a medical procedure for the treatment of vertebral compression fractures, the most common type of skeletal fractures related to osteoporosis.

Methods: This study compared the cement leakage and filling behavior of 2 existing delivery systems (Confidence and Vertebroplastic; DePuy Spine, Raynham, MA). The Confidence system with the high viscosity cement has been recently introduced in an attempt to curtail cement leakage.

A physical approach to modify the hydraulic reactivity of alpha-tricalcium phosphate powder.

A microsized alpha-tricalcium phosphate (alpha-TCP) powder was calcined at various temperatures (350 degrees C View Article and Find Full Text PDF

Mechanisms underlying the limited injectability of hydraulic calcium phosphate paste.

Calcium phosphate (CaP) cements are being increasingly used for minimally invasive hard tissue implantation. Possible approaches to improve the bad injectability of hydraulic calcium phosphate pastes have been discussed and investigated in a number of recent publications. However, the liquid-phase separation mechanism leading to the limited injectability has not yet been addressed.

Long-term effects of vertebroplasty: adjacent vertebral fractures.

In today's aging population, osteoporosis-related fractures are an ever-growing concern. Vertebroplasty, a promising yet cost-effective treatment for vertebral compression fractures, has an increasing role. The first vertebroplasty procedures were reported by Deramond and Galibert in France in 1987, and international interest grew with continued development of clinical techniques and augmentation materials in Europe and the United States.

High-viscosity cement significantly enhances uniformity of cement filling in vertebroplasty: an experimental model and study on cement leakage.

Study Design: Experimental study using a laboratory leakage model.

Objective: To examine the working hypothesis that high-viscosity cements will spread uniformly, thus significantly reducing the risk of leakage.

Summary Of Background Data: In vertebroplasty, forces that govern the flow of bone cement in the trabecular bone skeleton are an essential determinant of the uniformity of cement filling.

In vivo behavior of calcium phosphate scaffolds with four different pore sizes.

The goal of the present study was to assess the effect of macropore size on the in vivo behavior of ceramic scaffolds. For that purpose, beta-tricalcium phosphate (beta-TCP) cylinders with four different macropore sizes (150, 260, 510, and 1220 microm) were implanted into drill hole defects in cancellous bone of sheep and their resorption behavior was followed for 6, 12 and 24 weeks. The scaffolds were evaluated for biocompatibility, and new bone formation was observed macroscopically, histologically and histomorphometrically.

Setting properties of four acrylic and two calcium-phosphate cements used in vertebroplasty.

Study Design: Experimental study conducted in the laboratory with six different bone cements.

Objectives: To isolate the thermal properties of conventional and emerging bone cements used in vertebroplasty and to characterize their setting behavior.

Summary Of Background Data: The heat released during setting has been linked to the desirable effects of pain relief and tumor destruction and to the undesirable effect of thermal necrosis of surrounding tissue.

Ex vivo experiments of a new injection cannula for vertebroplasty.

Study Design: An experimental study using cadaveric vertebrae.

Objectives: To measure the injection pressure in an ex vivo model and determine whether the redesigned cannula, featuring 2 distinct sections of different diameters, significantly reduces the injection pressure.

Summary Of Background Data: An important limitation of vertebroplasty is the excessive pressure required to inject sufficient cement.

Biomechanical impact of vertebroplasty. Postoperative biomechanics of vertebroplasty.

Objectives: To examine the biomechanisms underlying adjacent fractures following vertebroplasty, an emerging procedure to stabilize fractured vertebrae. In this procedure, bone cement is injected percutaneously into the vertebral cancellous bone. Once hardened, the cement offers mechanical reinforcement to the weakened vertebra.

Clinical measurements of cement injection pressure during vertebroplasty.

Study Design: Clinical study of injection pressure during vertebroplasty.

Objectives: To investigate the range of injection pressures during conventional vertebroplasty interventions and to study the influence of syringe design and cement polymerization time on injection pressure.

Summary Of Background Data: Vertebroplasty is an efficient procedure for the treatment of painful vertebral fractures.