Performance Feedback

Smart technology that provides continuous data on drill bit function.

Only the SMARTdrill® can monitor drilling performance and deliver real time feedback on drill bit quality during surgery. Through instantaneous comparisons of cutting tool performance against empirical data, surgeons gain better insights to help them determine if the cutting tool is dull or clogged – before it’s too late and any damage is done to the target tissue.

Additionally, with the SMARTdrill®’s performance feedback capabilities, optimal drill bit performance is no longer hampered by human factors. With conventional drills, surgeons face unavoidable thermodynamic challenges and are forced to choose between the risk of burning and the risk of plunging. Today, SMARTdrill® technology allows the feed rate, or feed force, to be adjusted to the ideal for the specific bone density to optimize cutting, and minimize thermal injury. With the SMARTdrill®, plunge is no longer an issue, with plunging consistently and reliably limited to ≤ 0.5 mm.

Dilemma: Plunge or Burn?

The dilemma, when using a conventional drill, is demonstrated by the graph. Each red curve demonstrates the temperature of a specific drill bit as a function of the force applied. At the nadir of each red curve is the minimum temperature, or Tmin, achievable with that drill bit. The force at that point is the most efficient force for that drill bit (energy lost as heat = inefficiency).

The teal line, or plunge line, slopes up at a 45 degree angle for a conventional drill. On the red curve, as the force increases the drill bit and bone temperature decrease. But on the plunge line as the force increases the plunge increases, possibly to dangerous levels.

To drill, a certain amount of force must be applied. The surgeon must figure out how much force is enough to ensure that the temperature does not exceed some critical temperature, Tcritical, which should be < 47oC to prevent bone burning. Often it is desirable to select a temperature well below Tcritical to protect adjacent anatomical structures such as nerves.

The optimal trade-off between temperature and plunge occurs at the intersection of the two functions. Studies have demonstrated that experienced surgeons actually ease up on the drill as they anticipate breaching the distal cortex, thereby reducing the plunge1. Of course, there is a thermodynamic trade-off with extra heat being transferred. With conventional technology, the surgeon must always chose between Pmin and Tmin, they cannot have both. Hence the dilemma: to plunge or burn?

SMARTdrill®: Pmin and Tmin

The SMARTdrill® limits the plunge to ≤ 0.5 mm, or Pmin. The sloping teal line, or plunge line, becomes a flat line at 0.5 mm. Therefore, the operator can choose the optimal force to drill at (which is greater than Fmin). This results in the lowest possible temperature, Tmin. SMARTdrill® enables the surgeon to chose both Pmin and Tmin.

• Enables pre-operative testing of tools
• Provides intra-operative cutting performance determination
• Virtually eliminates thermal necrosis due to drilling
• Gives the surgeon a thermodynamic win-win ➝ Pmin and Tmin

In this picture, the operator drills down a clavicle model. The torque rises as he skives down the cortical wall, as shown on the fluoro shot for demonstration purposes. The operator redirects the drill away from the cortical wall the first time, the torque continues to rise indicating he is still skiving. Again, the fluoro shot is for demonstration purposes and does verify the skive position. The operator redirects a second time and the torque reduces, indicating he is no longer skiving. This is demonstrated with another fluoro shot.

3D Situational Awareness

The clinical SMARTdrill® is almost here! We have extended the SMARTdrill® preclinical platform to include 3D awareness in the newest model. Our sophisticated torque sensors allow for x-y plane awareness in addition to the previously available z-axis and skiving information. Now, the operator will be able to visualize in what axis the work is being done. For instance, if drilling down a bone mantle whether the torque is being sensed exactly in the z-axis (straight ahead, i.e. distally), in the x-axis or in the y-axis, the operator will be informed by the “targeting” output, see the figure to the right.

If the torque is simply distal to the bit, then the red dot will stay in the middle of the target. If the bit is skiving against a sidewall, the red dot will migrate towards the direction of the greatest resistance, for example the sidewall of a joint, the pelvic brim or a pedicle.

Interference Screw Detection

In this graph, the SMARTdrillbit® clears the first cortex and then encounters an intramedullary screw. Even after skiving off the screw, the distal cortex is visible using the SMARTdrill®. In addition, the plunge is prevented and the total drilling distance is displayed on the graphical user interface.

SMARTdrill® technology will help surgeons to make better-informed decisions toward fixation and help hospital administrators to manage costs of care through positive outcomes and reduced revision surgeries.