Purpose: The purpose of this study was to determine how to minimize intramedullary femur pressures, and therefore the risk of fat embolus syndrome, during surgical procedures which require preparation and instrumentation of the femoral canal.

Methods: To study intramedullary femur pressures and experimental model and a finite element model were developed. The experimental model ustilized a bone analogue which consisted of a porous plastic cylinder, having similar porosity and pore size to human femoral bone, with bone marrow being represented by a paraffin wax/petroleum jelly mixture. The finite element model consisted of a three dimensional analysis of a cylinder filled with bone marrow with a reamer advancing through it. Variables such as speed of insertion, fluid viscosity and relative diameters of the instrument and the inner diameter of the simulated bone were varied to see how they affected pressures.

Results: The intramedullary pressures increased with increasing speed of instrument insertion, increasing marrow viscosity, and increased diameter of the instrument relative to the inner diameter of the bone. Experimental and finite element results were in reasonable agreement.

Conclusions: We concluded that slower instrument insertion rates and a greater ratio of bone inner diameter to instrument diameter may minimize the intramedullary pressures and therefore minimize the risk of fat embolus syndrome. In addition, two novel techniques to analyze intramedullary femur pressures have been developed.

Funding : Education Grant

Funding Parties : NSERC