Resomer C212 © in vertebroplasty or kyphoplasty: A feasibility study on artificial bones with biomechanical and thermal evaluation

Abstract

BACKGROUND:

Vertebroplasty and kyphoplasty are now well-established methods for treating compression fractures of vertebral bodies (AO type A) as well as vertebral body metastases [1, 2, 3]. However, polymethylmethacrylate (PMMA) augmented vertebrae show fractures of subsequent vertebral bodies due to the increased stability of the augmented vertebral body [4]. Resorbable cements are currently only used experimentally. Many commercially available resorbable calcium phosphate cements do not exhibit sufficient biomechanical stability to treat vertebral body fractures [5]. Resomer C212 ${}^{\mathrm{\copyright }}$ (Evonik Industries AG, Essen, Germany) is a slow resorbable poly- $\epsilon$ -caprolactone that has low melting temperatures and good biomechanical properties.

OBJECTIVE:

This is a feasibility study on how the poly- $\epsilon$ -caprolactone Resomer C212 ${}^{\mathrm{\copyright }}$ can be used for kypho- or vertebroplasty, what temperatures are used in the argumentation and how differences in load capacity are measurable compared to conventional PMMA cement.

METHODS:

23 Sawbones ${}^{\mathrm{\copyright }}$ blocks (7.5 Open Cell Foam, SKU: 1522-09, laminated on both sides, 4 $\times$ 4 $\times$ 2.9 cm, Sawbones, Vashon Island, USA) were divided into three groups: 7 without augmentation, 8 augmented with PMMA cement Traumacem V ${+}^{\mathrm{\copyright }}$ (DePuy Synthes, West Chester, USA) and 8 augmented with Resomer C212 ${}^{\mathrm{\copyright }}$ . Temperature measurements were made in a 37 ${}^{\circ }$ C water bath centrally in the block and on the top and bottom plates. This was followed by a maximum load of up to 2000 N using a universal testing machine (Instron E 10000, Instron Industrial Products, Grove City, USA).

RESULTS:

In the Resomer C212 ${}^{\mathrm{\copyright }}$ test group, the maximum average increase in temperature was 4.15 $\pm$ 4.72 ${}^{\circ }$ C central, 0.3 $\pm$ 0.31 ${}^{\circ }$ C at the top and 0.78 $\pm$ 1.27 ${}^{\circ }$ C at the base. In the cement test group, the average increase in temperature was 9.80 $\pm$ 10.65 ${}^{\circ }$ C centrally in the test block, 1.50 $\pm$ 0.73 ${}^{\circ }$ C at the top plate and 1.42 $\pm$ 0.66 ${}^{\circ }$ C and the base plate. In the axial compression test, the 7 non-kyphoplasted test blocks showed a first loading peak on average at 275.23 $\pm$ 80.98 N, a rigidity of 238.47 $\pm$ 71.01 N/mm ${}^2$ . In the Traumacem V ${+}^{\mathrm{\copyright }}$ group, the mean peak load was 313.72 $\pm$ 46.26 N and rigidity was 353.45 $\pm$ 77.23 N/mm ${}^2$ . The Resomer C212 ${}^{\mathrm{\copyright }}$ group achieved a peak load of 311.74 $\pm$ 52.05 N and a stiffness of 311.30 $\pm$ 126.63 N/mm ${}^2$ . A compression to 50% could not be seen in any test block under the load of 2000 N. At 2000 N, Traumacem V ${+}^{\mathrm{\copyright }}$ ’s average height reduction was 9.26 $\pm$ 2.16 mm and Resomer C212 ${}^{\mathrm{\copyright }}$ was 10.93 $\pm$ 0.81 mm.

CONCLUSIONS:

It has been shown that the application of Resomer C212 ${}^{\mathrm{\copyright }}$ in kyphoplasty or vertebroplasty is well feasible. Thermal analysis showed significantly lower temperatures and shorter temperature application in the Resomer C212 ${}^{\mathrm{\copyright }}$ group. In the biomechanical load up to 2000 N no significant differences could be observed between the individual groups.