Mechanisches Versagen einer por�sen Hydroxylapatitkeramik 7,5�Jahre nach Implantation an der proximalen Tibia

Abstract

The treatment of osseous defects is widely established in the elderly. The number of positive reports on the successful application of bovine as well as coralline hydroxyapatite ceramics has continuously increased during the last few years. In trauma surgery hydroxyapatite ceramics are most commonly applied in metaphyseal defects evoked by traumatic fractures of the long bones. The bovine and coralline materials applied are biocompatible and exhibit an interconnecting porous system. Good osteoconductive properties of such materials have repeatedly been demonstrated. Due to possible harmful effects caused by abrasion of the material, intra-articular application should be strictly avoided. Biological degradation of the materials does not occur even during long-term follow-up. The application of hydroxyapatite ceramics was introduced at our institution in 1992. Since then, no adverse events have been observed and only a few relevant complications were described in the literature. We report on a patient revealing a mechanical failure of a bovine hydroxyapatite (Endobon) 7.5 years after implantation into a metaphyseal defect of the proximal tibia caused by a traumatic fracture.

Calcium Orthophosphates as Bioceramics: State of the Art

“…In general, the mechanical properties decrease significantly with increasing content of an amorphous phase, microporosity and grain size, while a high crystallinity, a low porosity and small grain size tend to give a higher stiffness, a higher compressive and tensile strength and a greater fracture toughness. Thus, calcium orthophosphate bioceramics possess poor mechanical properties (for instance, a low impact and fracture resistances) that do not allow use in load-bearing areas, such as artificial teeth or bones [46,47,48,49,50,51,52,276]. For example, fracture toughness [277] of HA bioceramics does not exceed ~1.2 MPa·m 1/2 [278] (human bone: 2–12 MPa·m 1/2 ).…”

Medical Application of Calcium Orthophosphate Bioceramics

“…Accordingly, from the mechanical point of view, calcium orthophosphate bioceramics appear to be brittle polycrystalline materials for which the mechanical properties are governed by crystallinity, grain size, grain boundaries, porosity and composition [203]. Thus, it possesses poor mechanical properties (for instance, a low impact and fracture resistances) that do not allow calcium orthophosphate bioceramics to be used in loadbearing areas, such as artificial teeth or bones [49][50][51][52][53][54][55]300] ). It decreases almost linearly with a porosity increasing [233].…”

Evaluation of degradable bone cements for percutaneous augmentation of bone defects

“…As a result, both novel cements combine two advantages, i. e. the possibility of percutaneous augmentation of bony defects and the subsequent degradation of the bone grafting material in conjunction with replacement by newly formed bone tissue after implantation, thereby avoiding the drawback of mechanical failure as observed after use of other bioactive bone grafting materials with very low degradation rates [2]. This work was funded by the European Union (EFRE-ProFIT grant 10141914).…”

“…These remnants provide mechanically weak points which can cause clinical problems in the long-term [2]. Therefore, bone grafting materials with improved properties are needed, i. e. bone substitute materials which allow bone bonding while being degradable at the same time.…”