INFLUENCE OF LONGITUDINAL-TORSIONAL ULTRASONIC-ASSISTED DRILLING ON THE SURFACE QUALITY AT THE DRILL SITE OF BOVINE FEMORAL CORTICAL BONE

Abstract

Precision and minimizing damage are crucial in orthopedic surgery, particularly in bone drilling procedures where bone integrity must be preserved. This research provides a detailed analysis of the effects of three drilling techniques: Conventional Drilling (CD), Longitudinal Ultrasonic-Assisted Drilling (LUAD), and Longitudinal-Torsional Ultrasonic-Assisted Drilling (LTUAD) on femur cortical bone. The study combines finite element modeling and experimental analysis in a comprehensive manner. The material properties of femur cortical bone are investigated to understand its stress response. Numerical simulations are employed to predict the thrust force induced during the interaction between the drill and the bone. The experimental phase involves creating and setting up a drilling test apparatus while defining the experimental variables and conditions. Following the drilling process, the samples are thoroughly examined, focusing specifically on differences in surface quality and delamination. This study aims to clarify the complex nature of bone drilling to improve surgical techniques and patient outcomes. Experimental results demonstrate that LTUAD consistently outperforms LUAD and CD in minimizing delamination and producing smoother drilled surfaces, particularly at higher rotational speeds. For example, at 350 RPM, LTUAD achieved smoother, more stable thrust forces and reduced delamination at the drill exit. LTUAD recorded a lower maximum thrust force (22 N) compared to LUAD (28 N) and CD (32 N), indicating reduced mechanical stress on the bone. Additionally, surface morphology analysis confirmed that LTUAD produced cleaner, more precise holes with less bone debris at higher speeds. These results highlight LTUAD's potential for enhancing surgical outcomes by reducing bone trauma, improving patient recovery, and ensuring greater implant stability. Further refinements in tool engagement and feed rate control could further optimize the efficiency of LTUAD, solidifying its application in orthopedic procedures.