**Acknowledgements**

*Latest Developments in Medical Robotics Systems*

**5. Discussion and conclusion**

the following dependencies stand out: Increasing the feed rate leads to:

the risk of thermal osteonecrosis

• Increasing the drill speed leads to:

osteonecrosis)

osteonecrosis)

handheld robotized systems.

bone drilling.

The drilling through the lateral cortex along the hip neck axis in fractures of the hip joint, as close as possible to the distal hip head cortex, can be performed successfully manually only under continuous X-ray control. This is of the utmost importance for stable fixation of the implant. The use of ODRO in this type of manipulations allows the use of surgical techniques associated with minimally invasive surgery.

The process of bone drilling is characterized by a set of input and output parameters. The input parameters define the conditions under which the process takes place, while the output parameters determine the outcome of the process.

The experiments are made by Computer Numerical Control (CNC) machines or CNC milling machines [39–41]. The purpose is to find such combinations of input parameters which may guarantee optimal output parameters during the process of

The difference between the experimental results of various studies arise for the sake of the wide variety of test conditions used by researchers regarding drill-bit diameter, drill bit type, rotational speed, feed rate and bone type. [42]. However,

• reducing the drilling time, i.e. reducing heat generation [43, 44], i.e. reduces

• increase of the thrust force [42], i.e. increase the risk of bone damage (traumatic

• increase in temperature [43, 45, 46], i.e. the risk of thermal osteonecrosis

the bone drilling process in order to obtain an optimal result.

• decrease of thrust force [42], i.e. reduces the risk of bone damage (traumatic

Summarizing, to minimize heat generation during drilling (avoid thermal osteonecrosis) one should work with the highest possible value of feed rate and the lowest possible value of drill speed. To avoid traumatic osteonecrosis it is necessary to work with the lowest possible value of feed rate and with the highest possible value of drill speed. Therefore, there are conflicting requirements regarding the values of the parameters drill speed and feed rate, which should be maintained (implemented) during

During the manual drilling these parameters are controlled by the surgeon on the base of his practical skills. But the optimal results of the manipulations can be assured only when the input parameters are under control during the automatic execution of the drilling process. This is the main reason for the appearance of the

Many scientific investigations are done concerning input parameters as drill speed, feed rate, different types of drill bit, its diameter, bone type and drilling methods. These parameters are responsible for heat generation, micro cracks, hole delamination, breakthrough detection and penetration. The results are reported only for the case when one of the parameters has a fixed value (drill speed) and the

other one has a discrete variation (feed rate) or vise versa.

**148**

This research is supported by the National Scientific Program eHealth in Bulgaria.
