Landmines continue to be a major cause of injury to both military and civilian personnel. This has lead to various strategies including the development of anti-landmine boots and vehicles. In an attempt to assess the efficacy of these strategies various physical and computer simulation models have been developed. International assessment technologies currently rely heavily on either live animal or human cadaver testing. Both these strategies are subject to wide individual variations and major practical and ethical problems. They are therefore not employed by the Australian Defence Organisation (ADO). A multi-disciplinary team has been assembled by the ADO to develop both a “flesh and bone” human model and a computer simulation. The biomechanical human analogue is constructed from materials that have been developed to reflect the strength properties and performance of human tissues (biofidelity). The surrogates are also equipped with various sensory devices allowing analysis of the local and remote effects of load transmission throughout the body. In the first stage of the program Frangible Synthetic Legs (FSL’s) were developed. These FSL’s have been blast tested in the presence of “protective” boots and vehicle platforms. These tests have yielded critical information on lower limb injury mechanisms and have highlighted the failings of some of these “protective” strategies. These frangible surrogate humans can be reproduced with great consistency and, once sufficiently evolved, should remove the need for experimental assessment on either live animals or human cadavers. Whilst the Human Surrogate technology has application in the development of mine resistant boot technologies, it is also transferable to the various aeronautic and automotive crash test injury programs which are currently deficient in model biofidelity.
The incidence of tarsal coalitions (TC) is not known. Most of the clinical studies report it as less then 1% but they disregard the asymptomatic coalitions. Two main theories have been elaborated regarding their etiology: 1) they result by incorporation of accessory bones into the nearby tarsals; 2) they occur as a result of the failure of differentiation and segmentation of the foetalmes-enchyme. Tarsal coalitions have been associated with degenerative arthritic changes. Computer tomography is the most commonly used diagnostic test in the detection of TC. The aims of our study were to establish the incidence of TC; the association between TC and accessory tarsal bones and between TC and tarsal arthritis; and to assess the sensitivity of CT as a diagnostic tool in TC. For this purpose we have undertaken coronal and sagittal CTs of 114 cadaveric feet which were subsequently dissected. The dissections identified 10 non-osseous tarsal coalitions, two talocalcaneal and eight calcaneonavicular. In nine cases we identified a synovial joint between the calcaneus and the navicular. We identified eight os trigonum, one accessory lateral malleolus bone, 38 sesamoid bones in the tendon of tibialis posterior and 19 sesamoid bones in the tendon of fibularis longus. Tarsal arthritis was identified in 37 cases. Both talocalcaneal coalitions were associated with talocal-caneal arthritis while none of the calcaneonavicular coalitions were associated with tarsal arthritis. The CT examination of five of the cases of calcaneonavicular coalitions showed one coalition and was suspicious of a coalition in another two instances. In conclusion our study demonstrated that the incidence of tarsal coalition is higher than previously thought (8.8%). The calcaneonavicular coalitions are more common (7%) but they do not seem to be associated with arthritic changes in the tarsal bones. The 7.9% of the calcaneonavicular synovial joint demonstrate that the “abnormality” of the calcaneonavicular space can take any form. Our preliminary CT results demonstrate a low sensitivity in the detection of nonosseous coalitions.
