We investigated the stability of seven Schatzker type II fractures of the lateral tibial plateau treated by subchondral screws and a buttress plate followed by immediate partial weight-bearing. In order to assess the stability of the fracture, weight-bearing inducible displacements of the fracture fragments and their migration over a one-year period were measured by differentially loaded radiostereometric analysis and standard radiostereometric analysis, respectively. The mean inducible craniocaudal fracture fragment displacements measured −0.30 mm (−0.73 to 0.02) at two weeks and 0.00 mm (−0.12 to 0.15) at 52 weeks. All inducible displacements were elastic in nature under all loads at each examination during follow-up. At one year, the mean craniocaudal migration of the fracture fragments was −0.34 mm (−1.64 to 1.51).

Using radiostereometric methods, this case series has shown that in the Schatzker type II fractures investigated, internal fixation with subchondral screws and a buttress plate provided adequate stability to allow immediate post-operative partial weight-bearing, without harmful consequences.

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.

In the assessment of fracture healing by monitoring stiffness with vibrational analysis or instrumented external fixators, it has been assumed that there is a workable correlation between stiffness and strength. We used four-point bending tests to study time-related changes in stiffness and strength in healing tibial fractures in sheep. We aimed to test the validity of the measurement of stiffness to assess fracture strength.

At each duration of healing examined, we found marked variations in stiffness and strength. Stiffness was shown to be load-dependent: measurements at higher loads reflected ultimate strength more accurately. There was a biphasic relationship between stiffness and strength: at first there was a strong correlation regardless of loading conditions, but in the second phase, which included the period of ‘clinical healing’, stiffness and strength were not significantly correlated.

We conclude that the monitoring of stiffness is useful primarily in assessing progress towards union but is inherently limited as an assessment of strength at the time of clinical union. Any interpretation of stiffness must take into account the load conditions.