Influences of Structural Properties of the Distal Tibia on the Compressive Strength of Interlocking Screws for Intramedullary Nails

Intramedullary (IM) nailing procedures for tibia fractures present the advantages of protecting the surrounding soft tissues at the distal tibia metaphysis. The current nails offer the options of putting a maximum of 3 screws distally. Locking the nail distally raises some valuable questions which are, to date, unanswered in literature. Following a previous work done at our lab on artificial sawbones, we expanded the study on cadaveric human bones in order to simulate, as much as possible, the mechanical behavior of in vivo applications. Our goal was to determine the most biomechanically stable configuration of distal locking screws for the treatment of distal metaphyseal tibia fractures with IM nails and, more importantly, the most efficient way to use surgical time and resources. Our results showed that a configuration with three locking screws could provide higher load carrying capacity than the two screws although not statistically significant. This work was also conducted to assess the impact of gender, age, cortical thickness, and cancellous bone density on the load carrying capacity of the bone samples.