A numeric approach for anatomic plate design.

Osteosynthesis plate designs with high levels of anatomical compliance have been demonstrated to have numerous clinical benefits. The purpose of this paper is to introduce a systematic numeric approach for anatomic plate design on the example of the distal medial tibia. The advantage of using numeric approaches for plate design is to gain objective and complete anatomical input as opposed to cadaveric investigations with limited sample sizes. A recent development in this area is a proprietary technology called SOMA which is based on a large database of 3D bone models generated from thin-slice computer tomographic scans plus associated software tools. In this paper, one of these associated software tools is described which automatically assesses the anatomic fit of osteosynthesis plates based on a large database of bone models. As an example, this tool was applied to assess the mean plate to bone distance of distal medial tibia plates, when fitted onto 444 Caucasian and 310 Asian 3D bone models respectively. The analyses revealed differences in the anatomical compliance of plates from different generations and manufacturers. The anatomical compliance of SOMA designed plates was statistically significantly better compared to all other plates in all groups "Short", "Intermediate" and "Long" and for both ethnicities "Caucasian" and "Asian" (P<0.001). The study has shown that using an underlying database with accompanying computational tools such as SOMA can be a powerful and efficient approach towards the development and advancement of osteosynthesis plates in trauma surgery, ultimately resulting in plates with high levels of anatomical compliance and potential clinical benefits.

Infrapatellar vs. suprapatellar approach to obtain an optimal insertion angle for intramedullary nailing of tibial fractures.

BACKGROUND: During intramedullary nailing of tibial fractures, the insertion angle of the nail is of great importance. When the nail impacts the posterior cortex due to a large insertion angle with a dorsal target course, higher insertion forces are needed, and the danger of iatrogenic fractures increases. Accordingly, the insertion direction should be as parallel as possible to the longitudinal axis of the tibia. We aimed to confirm the hypothesis that intramedullary nailing of tibial fractures can be performed with smaller insertion angles via a suprapatellar approach rather than infrapatellar approach. METHODS: In 19 human bodies of donors with intact tibiae, we performed intramedullary nailing by both a suprapatellar and an infrapatellar approach. The correct entry point was determined by fluoroscopy. Subsequently, the medullary canal was reamed up to a diameter of 10 mm, and a 9 mm polytetrafluorethylen tube was inserted instead of a tibia nail. The angle between the proximal aspect of the tube and the longitudinal axis of the tibia was measured using a computer-assisted surgery system. RESULTS: The angle between the proximal aspect of the inserted tube, simulating the tibial nail, and the longitudinal tibial axis was significantly larger when using the infrapatellar approach. CONCLUSIONS: We achieved an insertion angle significantly more parallel to the longitudinal axis when using a suprapatellar approach for intramedullary nailing of tibial fractures. Thereby, both the risk of iatrogenic fracture of the posterior cortex and apex anterior angulation of the short proximal fragment can be reduced during intramedullary nailing of tibial fractures.