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Drilling Energy and Implant Strength

Drilling Energy (“DE”) correlates strongly with screw pullout strength (“POS”).

In the graph above, the ‘Drilling Energy’ to drill a hole in SawbonesTM materials with a 3.2 mm drill bit is plotted on the x-axis. The linear ‘Pullout Force’ (strength) associated with a 4.5 mm self-tapping screw placed into that hole is plotted on the y-axis. A strong correlation (R = 0.972, R2 = .94564) is demonstrated.

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Drilling Energy and the SMARTdrill™

The SMARTdrill® displays the drilling energy in Joules (J) in the Energy Output Box at the top left of the graphical user interface (see below) next to the Position Output Box. In the example pictured, the drilling energy was ~25 J for this 3.2 mm drill bit. On the graph above, 25 J of drilling energy correlates to about 400 N of pullout strength if a 4.5 mm self-tapping screw is secured into this hole. Since SMARTdrill® measures Drilling Energy the surgeon will know how much energy is stored in each screw. Therefore, the surgeon will know when enough screws are placed (from empirical data stored in SMD’s Global Bone Database) to achieve the construct strength that is optimal for healing. For those who want to achieve balanced fixation, they can simply compare the energy stored on each side of the fracture. Finally, the surgeon will be able to rest assured that adequate implant purchase and construct strength have been obtained.