How much force should the surgeon apply for surgical power tools use in knee and hip surgeries ?

The force applied by the surgeon in the use of surgical power tools in knee and hip surgeries directly affects the amount of heat generated in cutting / drilling operations. In order not to cause bone necrosis, it is very important to examine all the factors that create the heat in the application process.

Past studies on knee and hip surgeries

A number of studies have been conducted showing that the applied force directly affects the heat. Krause et al. (1982) tried to measure the force and temperature response with a reciprocating saw blade. In order to record the saw blade temperature, a thermocouple was attached to it. The saw blade reached temperatures in excess of 200°C without any coolant irrigation. It was stated that the force applied by the surgeon was between 4.5 Nm and 7.5 Nm. (Parsa, 2006)

James T.P. et al. (2013) applied two different forces (15 Nm and 30 Nm) in their study. They revealed that the increase in the applied force along with the speed of the surgical motor significantly reduces the heat generated in the bone. When the applied force increases, the temperature decreases because the surgical saw blade contacts the bone for a shorter time.

In a study investigating lower drilling forces, cortical temperatures increased when the applied force increased from 1.5 Nm to 4 Nm (Abouzgia and James, 1997). But then they found that as the forces increased from 4 Nm to 9 Nm, the cortical temperatures decreased. Besides; Researchers such as Matthews and Hirsch (1972), Abouzgia and Symington (1996) and Brisman (1996) have reported that cortical bone temperatures are inversely related to drilling force. Each observed a significant decrease in maximum cortical temperatures as a result of the increase in force.

Matthews and Hirsch (1972), in agreement with Bachus et al. (2000), tested forces ranging from 20 Nm to 118 Nm and found that by increasing the force, the duration of bone temperatures above 50 °C decreased. While the exact reason for this temperature drop is unclear, a higher force reduces the time it takes to penetrate the cortex of the bone. (Parsa, 2006).

A multifactorial study of drilling processes showed that an increase in drilling speed up to a certain level results in a higher temperature increase in bone. But in the same study, an increase in applied force generally resulted in a lower temperature rise. (Augustin G. et al., 2008)


The force applied by the user is an action that lowers the temperature as it reduces the contact time with the bone. However, an uncontrolled force applied to the bone in knee and hip surgeries can cause other damages. A randomly applied force can result in damage to muscles and tissues.

In knee arthroplasty, if the blade moving in the guide hits the opposite ecarteur or the guide edges, the sharpness of the surgical saw blade will decrease. In other words, a process made to lower the temperature will cause a blunt saw blade, that is, an increase in the temperature in the cutting process.

For these reasons, in knee and hip surgeries, the most aggressive cut should be applied in a controlled manner.

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  • Augustin G, Davila S, Mihoci K, Udiljak T, Vedrina DS, Antabak A. Thermalosteonecrosis and bone drilling parameters revisited. Arch Orthop Trauma Surg 2008;128:71–7.
  • James T.P et all (2013) Effect of applied force and blade speed on histopathology of bone during resection by sagittal saw. Elsevier Medical Engineering & Physics, 364-370.
  • Krause, W. R., Bradbury, D. W., Kelly, J. E., Lunceford, E. M., (1982). Temperature elevations in orthopaedic cutting operations. Journal of Biomechanics 15, 267-275.
  • Matthews, L. S., Hirsch, C., (1972). Temperatures measured in human cortical bone when drilling. The Journal Of Bone And Joint Surgery.American Volume 54, 297-308.
  • Parsa, Hamid Khalili. An Investigation into the Temperature Distribution Resulting from Cutting of Compact Bone Using a Reciprocating Bone Saw. 2006: 26-27.

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