Design and Implementation of a Control System to Mitigate Osteonecrosis in Orthopedic Bone Drilling Procedures

The drilling process in orthopedic surgery can sometimes lead to an undesired increase in temperature,which can cause serious damage to bones and soft tissues.This overheating is typically identified as a temperature above 47℃,known as the critical limit,and can result in the condition known as osteonecrosis.This study aims to develop a new control system,using a proportional-integral-derivative(PID)controller,to prevent overheating and the resulting osteonecrosis.The bone temperature is constantly measured using a thermocouple and,when it reaches the critical temperature of 47℃,the cooling device is activated by the PID-controlled system.This new control system makes the drill machine with cooling device more user-friendly and allows surgeons to set a desired temperature level manually.

Vertebral Bone Drilling (Puncture) Attenuates the Intractable Pain Due to Vertebral Fractures without Collapse

Purpose: Osteoporotic vertebral fractures with no sign of vertebral collapse on initial radiographs, which is so-called occult vertebral fractures (VFs), exist. Occult VFs have a high rate of missed diagnosis, and the treatment of these fractures has rarely been discussed in the literature. We evaluated the effects of vertebral bone drilling for the pain due to occults VFs. Materials and Methods: Eighteen patients with painful osteoporotic occult VFs underwent the vertebral bone drilling. We evaluated the clinical outcome by comparing numerical rating scale (NRS) and activity of daily life (ADL) values between before and after the vertebral bone drilling. Comparisons were made by using Wilcoxon signed rank test. Results: The mean baseline NRS and ADL score, and the mean NRS and ALD score after the bone drilling were 8.4 ± 0.8, 2.2 ± 0.6, 2.4 ± 1.0, 4.6 ± 0.5, respectively. Among the patients, we detected significant improvements in NRS pain score and ADL score after the drilling compared with baseline score (p < 0.0002). Conclusion: Vertebral bone drilling at the site of painful vertebral compression fractures alleviated the intractable pain due to osteoporotic occult VFs.

Evaluation of temperature distribution for bone drilling considering aging factor

Bone drilling is a routine operation in surgeries,such as neurosurgery and orthopedics.However,the excessive drilling temperature may cause severe thermal damage to the bone tissue.Therefore,the drilling temperature determination of bone tissue can reduce the harm caused by thermal damage.A time-varying temperature field simulation model of bone drilling was set up by ABAQUS software in this paper,based on the Johnson-Cook model.Then it was validated with experiments by drilling cortical bone of fresh bovine shaft of the femur.The relative error between the experimental values and the theoretical values within 7.67%showed a good consistency.Furthermore,the aging factor is also considered to evaluate the temperature field of bone drilling.The results showed that the drilling temperature near the bone-drill area increased significantly.The drilling temperature of cortical bone decreases sharply with the radial distance and exhibits a hysteresis lag in the axial distribution.The aging factor mainly affects the peak of drilling temperature.The peak of drilling temperature tends to increase with age.The peak drilling temperature in the elderly(70y)was up to 6.8%higher than that in the young(20y),indicating that the elderly is more prone to excessive drilling temperature.Therefore,special attention should be paid to the temperature control of elderly bone tissue.

Drilling Force and Temperature of Bone under Dry and Physiological Drilling Conditions

Many researches on drilling force and temperature have been done with the aim to reduce the labour intensiveness of surgery, avoid unnecessary damage and improve drilling quality. However, there has not been a systematic study of mid- and high-speed drilling under dry and physiological conditions（injection of saline）. Furthermore, there is no consensus on optimal drilling parameters. To study these parameters under dry and physiological drilling conditions, pig humerus bones are drilled with medical twist drills operated using a wide range of drilling speeds and feed rates. Drilling force and temperature are measured using a YDZ-II01W dynamometer and a NEC TVS-500EX thermal infrared imager, respectively, to evaluate internal bone damage. To evaluate drilling quality, bone debris and hole morphology are observed by SEM（scanning electron microscopy）. Changes in drilling force and temperature give similar results during drilling such that the value of each parameter peaks just before the drill penetrates through the osteon of the compact bone into the trabeculae of the spongy bone. Drilling temperatures under physiological conditions are much lower than those observed under dry conditions, while a larger drilling force occurs under physiological conditions than dry conditions. Drilling speed and feed rate have a significant influence on drilling force, temperature, bone debris and hole morphology. The investigation of the effect of drilling force and temperature on internal bone damage reveals that a drilling speed of 4500 r/min and a feed rate of 50 mm/min are recommended for bone drilling under physiological conditions. Drilling quality peaks under these optimal parameter conditions. This paper proposes the optimal drilling parameters under mid- and high-speed surgical drilling, considering internal bone damage and drilling quality, which can be looked as a reference for surgeons performing orthopedic operations.

Measurement of Forces and Torques during Non-Homogeneous Material Drilling Operation

The purpose of this study is to measure the forces and torques produced in the drilling process of a non-homogenous material （bone）. An automated 5 DoF CataLyst-5 robot is used during the drilling process and it is integrated to a 6 DoF force-torque sensor. A force-torque controller which is built in the Matlab Simulink environment is employed to control the drilling process of the bone. Different feed rate is used during the experimental process of the bone drilling operation. The sensor is calibrated to measure the tri-axial direction of the resultant forces and torques. The profiles of the forces and torques obtained are non-linear due to the diversity of the bone density. The profiles generated also indicated fluctuation in the interface layers of the bone.