Influence of cerclages on primary stability of tumor megaprostheses subjected to distal femur defects

Abstract Backround Purpose of this experimental study was to investigate the influence of cerclages on the primary stability of the MUTARS ® system using distally fractured synthetic femora. Methods 4 MUTARS ® prostheses were implanted in synthetic femora respectively. Groups consisted of 4 intact bones, 4 fractured with cerclages and 4 fractured bones without cerclages. Spatial micromovements were measured with a high-precision rotational setup. Findings The order from the weakest to the strongest torque transmission of the intact bones was rm 1 -rm 4 -rm 2 -rm 3 ( p  = 0.011) and of the fractured bones with cerclages rm 4 -rm 1 -rm 3 -rm 2 ( p  = 0.013). The MUTARS ® stems broke out of the fractured femoral shaft by removing cerclages ( p p p p Interpretation Due to high press-fit at the proximal and distal isthmus region fissural fractures of the femur may occur. This should always be taken into account. It is advisable to secure them and provide a prophylaxis for these fissural fractures by means of cerclages.