title: Mechanical testing of an absorbable hybrid fusion cage for the cervical spine.
abstract: Conventional fusion devices ("cages") are often used to join two vertebrae of the human spine and generally remain in the body for a lifetime and can theoretically lead to any complications. Therefore, an absorbable hybrid fusion cage consisting of a magnesium skeleton infiltrated with an absorbable polymer [poly-ε-caprolactone (PCL)] has been developed. The primary objective of the cage is to ensure an adequate stiffness of the disc space directly after the operation and to encourage the ingrowth of the new bone tissue to secure long life stability. Once a sufficiently rigid bone connection is formed, the implant should be absorbed. The purpose of this first study on the new absorbable fusion cage was to investigate the mechanical properties in vitro. Tensile tests were performed with tensile specimens type 1BA according to DIN EN ISO 527 made of PCL foamed using controlled expansion of saturated polymers (CESP). Furthermore, cyclic compression tests and compression tests with steady movement were performed with different designs of the new cage. Compression tests were also performed with vertebral endplates of ovine cadaveric spines. Foaming of PCL resulted in a modulus of elasticity of 135 MPa, which is approximately one third of unfoamed PCL. The results indicate that the initial compression strength of the implants should be adequate for the implantation in the cervical spine.
authors: Institute of Plastics Processing at RWTH Aachen, Pontstr. 49, 52062 Aachen , Germany. kauth@ikv.rwth-aachen.de
authors: Theresa
authors: T
authors: Kauth
authors: Christian
authors: C
authors: Hopmann
authors: Bernd
authors: B
authors: Kujat
authors: Friedrich W
authors: FW
authors: Bach
authors: Bastian
authors: B
authors: Welke
authors: Christof
authors: C
authors: Hurschler
authors: Katharina
authors: K
authors: Kalla
authors: Dorothea
authors: D
authors: Daentzer
mesh_terms: D020341:Absorbable Implants; D002208:Caproates / Q000737:chemistry* / Q000378:metabolism*; D002574:Cervical Vertebrae / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D007783:Lactones / Q000737:chemistry* / Q000378:metabolism*; D008274:Magnesium / Q000737:chemistry* / Q000378:metabolism*; D011108:Polymers / Q000737:chemistry* / Q000378:metabolism; D013123:Spinal Fusion / Q000379:methods*
chemical_list: D002208:Caproates; D007783:Lactones; D011108:Polymers; C121056:caprolactone; D008274:Magnesium