Biomechanical evaluation of the less invasive stabilization system and the 95-degree angled blade plate for the internal fixation of distal femur Fractures in human cadaveric bones with high bone mineral density.

BACKGROUND

The less invasive stabilization system (LISS) is an internal fixator that utilizes unicortical locked screws for fixation of distal femur fractures. A question is whether locked unicortical screw fixation is sufficient, when compared with a standard implant such as a blade plate.

METHODS

Eight matched pairs of fresh-frozen cadaveric femora were instrumented with either the LISS or a 95-degree blade plate. A 4-cm supracondylar gap fracture model was created and all bone-implant constructs were tested to failure in axial loading.

RESULTS

All constructs failed by plastic deformation of the implant. There was no significant difference between the LISS and the blade plate constructs with respect to load to failure.

CONCLUSIONS

Despite unicortical fixation axial loading to failure of the LISS did not result in implant/screw pull-out neither proximally nor distally. However, there does not appear to be a biomechanical advantage of using the LISS as opposed to a blade plate in bones with high bone mineral density.