Long bone fractures are a commonly presented paediatric injury. Whilst the possibility of either accidental or non-accidental aetiology ensures significant forensic relevance, there remain few clinical approaches that assist with this differential diagnosis. The aim of this current study was to generate a reproducible model of spiral fracture in immature bone, allowing investigation of the potential relationship between the rotational speed and the angle of the subsequent spiral fracture. Seventy bovine metacarpal bones were harvested from 7 day old calves. Sharp dissection ensured removal of the soft tissue, whilst preserving the periosteum. The bones were then distributed evenly before eleven groups, before being aligned along their central axis within a torsional testing machine. Each group of bones were then tested to failure at a different rotational speed (0.5, 1, 15, 20, 30, 40, 45, 60, 75, 80 and 90 degrees s-1). The angle of spiral fracture, relative to the long axis, was then measured, whilst the fracture location, the extent of comminution and periosteal disruption, were all recorded. Sixty-two out of 70 specimens failed in spiral fracture, with the remaining tests failing at the anchorage site. All bone fractures centred on the narrowest waist diameter, with 5 specimens (all tested at 90 degrees s-1) demonstrating comminution and periosteal disruption. The recorded spiral fracture angles ranged from 30 - 45 degrees, and were dependant on the rotational speed. This study has established a relationship between the speed of rotation and the angle of spiral fracture in immature bovine bone. It is anticipated that further study will enable investigation of this trend in paediatric bone, ultimately providing an additional diagnostic tool for clinicians trying to verify the proposed mechanism of injury

The re-establishment of vascularity is an early event in fracture healing; upregulation of angiogenesis may therefore promote the formation of bone. We have investigated the capacity of vascular endothelial growth factor (VEGF) to stimulate the formation of bone in an experimental atrophic nonunion model.

Three groups of eight rabbits underwent a standard nonunion operation. This was followed by interfragmentary deposition of 100 μg VEGF, carrier alone or autograft.

After seven weeks, torsional failure tests and callus size confirmed that VEGF-treated osteotomies had united whereas the carrier-treated osteotomies failed to unite. The biomechanical properties of the groups treated with VEGF and autograft were identical. There was no difference in bone blood flow.

We considered that VEGF stimulated the formation of competent bone in an environment deprived of its normal vascularisation and osteoprogenitor cell supply. It could be used to enhance the healing of fractures predisposed to nonunion.