Investigation on the use of a magnesium alloy as a new resorbable implant material for orthopaedic surgery.Original Title Untersuchungen zum Einsatz einer Magnesium-basislegierung als neues resorbierbares Implantatmaterial fur die Osteosynthese.

摘要

In the present in vivo study, a magnesium alloy was investigated within the scope of a long term study in a rabbit model. The corrosion stability and the mechanical properties were optimized through lithium, aluminium and rare elements to the magnesium alloy (LAE442). Extruded implants (2.5 mm x 25 mm) of the resorbable magnesium alloy LAE442 were implanted into the bone marrow cavity of both tibiae of New Zealand White rabbits for three, six and twelve months each. The tolerability and degradation of the implants were investigated through clinical and radiological investigations. At the end of the investigation period, the implants of the left tibia were assessed using scanning electron microscopy including element analysis. In addition, weight and volume of the implants were determined and three point bending tests were carried out. The implants from the right tibiae remained in the bone-implant compound and were examined both in the micro CT and histologically. The rabbits were in a good general condition over the whole experimental period and showed no signs of lameness. Radiographic examinations could not reveal any generation of gas. At the end of the investigation period implants were still in existence, but showed a distinct loss of mass. With increasing implantation duration, the element analysis showed a decrease of magnesium and an increase of potassium and phosphorus on the surface of implants. Weight and volume measurements revealed a distinct reduction in the course of implantation time. The mechanical properties showed a decrease of the maximal force of 71.2%. micro CT revealed a regular degradation over time and endosteal new bone formation could be observed. With histological investigation, good biocompatibility and endosteal and periosteal remodelling could be proved. Surface corrosion and cell adhesions could be seen on all implants.