The Frangible Surrogate Leg (FSL) model was first developed by Australia’s Defence Science and Technology Organisation (DSTO) during the late 1990’s as part of its Human Surrogate Program, led by Dr. Alexander Krstic. The NATO recognised FSL was engineered to physically model the lower human extremities and consequently enable the evaluation of anti-personnel (AP) landmine mitigation strategies, increase soldier survivability and eliminate the requirement to test using cadaver or animal tissues. Over 175 FSL’s have been tested within DSTO programs. FSL variants have also been used in rapid platform acceleration environments such as within land vehicles subjected to anti-vehicular (AV) landmines, usually attached to an anthropomorphic mannequin such as the Hybrid III.

The FSL is constructed from materials simulating bone, cartilage, connective tissue and soft tissue, engineered to provide a reproducible response to loading whilst incorporating substantial anatomical accuracy.

The principal method of injury assessment is standard medical examination, both physically and radiographically, to diagnose outcomes that often include dislocations, fractures and traumatic amputations. 

To facilitate use on the Hybrid III, the FSL was shortened and modified to create the FSLLM and can be coupled with a clevis attachment that interfaces with the Hybrid III knee joint. A cylindrical section was also included within the upper tibia that can be fitted with strain gauges to allow measurement of local bending and compression. 

Recently, Adelaide T&E Systems has enhanced the FSLLM through the implementation of more advanced manufacturing techniques, materials and the inclusion of a biofidelic, layered heel pad. An advanced mould ensures all bones are precisely positioned and a vacuum assisted low pressure injection technique is used to connect all bones with a joint space simulating, synthetic compound. A second similar technique adds a different synthetic compound that simulates cartilage and connective tissue in the form of a ‘ligamentous capsule’. The layered heel pad is constructed separately using biological materials impregnated with synthetic soft tissue simulant. The components are then accurately positioned in the final mould. Lastly, a synthetic soft tissue simulant is cast around the assembled skeletal structure, securing the heel pad in place and ensuring reproducible soft tissue thickness within the heel and sole of the foot. This enhanced FSLLM eliminates the use of temperature sensitive gelatin based materials (giving the user the freedom to test in ambient temperatures), provides an enhanced biofidelic response and allows failed specimens to be kept indefinitely for reference

Adelaide T&E Systems can provide the FSLLM in both instrumented and plain configurations. Please be advised that this product is generally subject to minimum order quantities.

More information about the FSL can be found in a recently released DSTO-TR-1829 document titled ‘Development and Calibration of a Frangible Leg Instrumented for Compression and Bending’, available here for download.