Primary stability of wave plate Experimental study
Axial loading produces compression force on medial cortex and tension on lateral cortex at femoral fractures fixed by plate. The wave in the plate could have an adverse effect by increasing the moment arm, but lateral cortex would support the compressive force. Wave plate would allow grafting on lateral cortex and also preserve blood supply. This experimental study is designed to search primary stability of wave plate. Defected fractures on twenty sheep’s femurs were fixed with wave plate on the right and with standard small fragment plate on the left. Five mm. wave was made on ten right femurs and ten mm. wave was made on the other ten right femurs. Accelerated axial loading was applied to all femurs and the results were recorded. Loading which closed the defect was accepted as primary loading value (F1) and also loading which deformed the plate screw complex was accepted as maximum loading value (F2). There were not any significant differences between 5 mm. wave plate and standard plate on F1 and F2. Ten mm. wave plate was less stable than standard plate on primary loading value (F1) but stable on maximum loading value (F2). We concluded that the wave plate application is stable while wave’s height is 1/3 diameter of femoral shaft as standard plate. Higher waves would decrease the primary stability of the wave plate.