Elsevier

The Spine Journal

Volume 15, Issue 5, 1 May 2015, Pages 1092-1098
The Spine Journal

Basic Science
Height restoration of osteoporotic vertebral compression fractures using different intravertebral reduction devices: a cadaveric study

https://doi.org/10.1016/j.spinee.2013.06.094Get rights and content

Abstract

Background

The treatment of osteoporotic vertebral compression fractures using transpedicular cement augmentation has grown significantly during the past two decades. Balloon kyphoplasty was developed to restore vertebral height and improve sagittal alignment. Several studies have shown these theoretical improvements cannot be transferred universally to the clinical setting.

Purpose

The aim of the current study is to evaluate two different procedures used for percutaneous augmentation of vertebral compression fractures with respect to height restoration: balloon kyphoplasty and SpineJack.

Materials and methods

Twenty-four vertebral bodies of two intact, fresh human cadaveric spines (T6–L5; donor age, 70 years and 60 years; T-score −6.8 points and −6.3 points) were scanned using computed tomography (CT) and dissected into single vertebral bodies. Vertebral wedge compression fractures were created by a material testing machine (Universal testing machine, Instron 5566, Darmstadt, Germany). The axial load was increased continuously until the height of the anterior edge of the vertebral body was reduced by 40% of the initial measured values. After 15 minutes, the load was decreased manually to 100 N. After postfracture CT, the clamped vertebral bodies were placed in a custom-made loading frame with a preload of 100 N. Twelve vertebral bodies were treated using SpineJack (SJ; Vexim, Balma, France), the 12 remaining vertebral bodies were treated with balloon kyphoplasty (BKP; Kyphon, Medtronic, Sunnyvale, CA, USA). The load was maintained during the procedure until the cement set completely. Posttreatment CT was performed. Anterior, central, and posterior height as well as the Beck index were measured prefracture and postfracture as well as after treatment.

Results

For anterior height restoration (BKP, 0.14±1.48 mm; SJ, 3.34±1.19 mm), central height restoration (BKP, 0.91±1.04 mm; SJ, 3.24±1.22 mm), and posterior restoration (BKP, 0.37±0.57 mm; SJ, 1.26±1.05), as well as the Beck index (BKP, 0.00±0.06 mm; SJ, 0.10±0.06), the values for the SpineJack group were significantly higher (p<.05)

Conclusion

The protocols for creating wedge fractures and using the instrumentation under a constant preload of 100 N led to reproducible results and effects. The study showed that height restoration was significantly better in the SpineJack group compared with the balloon kyphoplasty group. The clinical implications include a better restoration of the sagittal balance of the spine and a reduction of the kyphotic deformity, which may relate to clinical outcome and the biological healing process.

Introduction

Vertebroplasty and kyphoplasty, the percutaneous injection of various bone cements into affected vertebral bodies, are used commonly to treat painful osteoporotic vertebral fractures. The technique of percutaneous injection was first described by Galibert et al. [1]. Following the introduction of balloon kyphoplasty [2], in which a void in the vertebral body is created using an inflatable balloon before cement augmentation, treatment using both procedures has been increasing significantly.

According to the criteria of evidence-based medicine, there are only two level Ib evidence studies [3], [4] that show the benefits of balloon kyphoplasty compared with conservative treatment, especially during the early stage after osteoporotic fracture. However, the study results are limited to clinical benefits such as pain and do not examine kyphotic correction. The level Ia studies comparing vertebroplasty with conservative treatment show inconsistent results and have been discussed in detail elsewhere [5], [6]. Several systematic reviews have also reported efficacy with regard to significant pain reduction in 87% of patients undergoing vertebroplasty and in 92% of patients undergoing kyphoplasty [7]. Overall, the complication rate of both procedures is considered to be low [7], [8], [9].

Balloon kyphoplasty was designed to improve patient safety during augmentation procedures—in particular, to reduce the rate of cement leakage. Another advantage compared with percutaneous vertebroplasty was supposed to be the possibility of reducing the fracture during balloon inflation. Correction of sagittal alignment, reducing the kyphotic angle, and improvement of the vital capacity of the lungs were supposed to be other advantages.

One procedural disadvantage of balloon kyphoplasty is that the balloons have to be removed after height restoration and before cement injection. This balloon deflation can lead to a significant loss of the previously restored height [10], [11]. To circumvent the loss of height restoration, before cement augmentation, a reduction device was designed that would stay inside the vertebral body during cement augmentation.

A theoretical advantage of the SpineJack device is that the force needed to reduce the fracture can be directed in the craniocaudal direction. In balloon kyphoplasty, individual anatomy and the balloon decide where the force is directed.

There is still uncertainty about the clinical importance of height restoration. Reducing fractures in combination with improved sagittal kyphosis is supposed to show better long-term effects. The improved vital capacity of the lungs as well as a reduction of adjacent fractures are advantages of an anatomic reduction of the fractured vertebrae.

Thus, we examined biomechanical behavior and height restoration using the SpineJack device compared with balloon kyphoplasty in osteoporotic vertebral compression fractures.

Section snippets

Specimens

To analyze the characteristics of the balloon kyphoplasty and SpineJack procedures, it was necessary to create similar conditions for both devices. For this reason, all devices were investigated in the vertebral bodies of two fresh, frozen human cadaveric spines (T6–L5). The donors were two women (age, 70 years and 60 years). Specimens were stored at −20°C. Before surgery a computed tomographic (CT) scan of the spine was performed to identify any pathologies, especially preexisting vertebral

Results

For all parameters determined, the results are expressed as mean±standard deviation. The test of significance between results from study pairs was conducted by using the Wilcoxon Mann-Whitney U test and Student t test with significance set a p<.05.

Compression fractures could be established in all vertebral bodies. According to the Orthopedic Trauma Association classification they were all A-type fractures [12]. The average force needed to create the fracture was 2,784.2 N (range,

Discussion

This article has both a methodological and a scientific aim. Methodologically, the objective was to develop a custom-made loading frame that allowed a constant preload during instrumentation of the vertebral bodies. Scientifically, the focus was on examining the differences in height restoration of two techniques used in vertebral augmentation procedures: balloon kyphoplasty and the SpineJack procedure.

The first aim of this study was to establish this method, and we found it was possible to

Conclusion

A study using cadaveric vertebrae was designed to examine the height restoration of two different augmentation procedures used to treat vertebral compression fractures. The protocols for creating wedge fractures, and the instrumentation under a constant preload of 100 N led to reproducible results and effects.

The study showed that sagittal height restoration was significantly better when using SpineJack than balloon kyphoplasty. The clinical implications include better restoration of the

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  • Cited by (0)

    FDA device/drug status: Approved (Inflatable Bone tamp; Kyphon Medtronic); Investigational (SpineJack, Vexim, SAS CE marked; under clinical investigation).

    Author disclosures: AK: Support for travel to meetings for the study or other purposes: Vexim (B); Provision of writing assistance, medicines, equipment, or administrative support: Spines and equipment were provided by Vexim (C); Consulting: Vexim (B), Medtronic (B), Soteira (B), Dfine (B); Speaking and/or Teaching Arrangements: Vexim (B), Medtronic (B), Soteira (B), Dfine (B); Trips/Travel: Vexim (B), Medtronic (B), Soteira (B), Dfine (B). LO: Nothing to disclose. JF: Consulting fee or honorarium: Vexim SA (A); Support for travel to meetings for the study or other purposes: Vexim SA (A); Fees for participation in review activities such as data monitoring boards, statistical analysis, end point committees, and the like: Vexim SA (A). FF: Nothing to disclose. FB: Other: PhD is funded by Vexim (reimbursement). DCN: Consulting: Vexim (D), SAS (D), Spineart (D). SR: Nothing to disclose.

    The disclosure key can be found on the Table of Contents and at www.TheSpineJournalOnline.com.

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