Evaluation of bone strength: Correlation between measurements of bone mineral density and drilling force

Abstract

Bone drilling is a major part of modern orthopaedic surgery which involves the internal fixation of fractured bones. The investigation of bone drilling described in this paper demonstrates the contribution of automation technology towards the study of bone strength. The aim of this preliminary investigation is to establish a relationship between bone drilling forces and measurements of bone mineral density (BMD) by dual energy X-ray absorptiometry (DXA). A linear relationship with a high coefficient of correlation has been found between average drilling forces and BMD measurements at both the greater trochanter and the femoral head of porcine femurs when drilling in the anterior-posterior (AP) direction (i.e. the direction of the DXA scan). It has also been found that in the normal drilling direction (i.e. in the cervical axis direction), which is orthogonal to the DXA scanning direction, there are similar trends between the drilling forces and BMD levels in regions where bone density is more consistent (e.g. the femoral head). The findings of this investigation indicate that analysis of bone drilling forces has the potential to provide useful information about the strength of bone.

Biomechanical Measurements of Surgical Drilling Force and Torque in Human Versus Artificial Femurs

“…Prior experimental and computational studies have assessed various parameters that influence surgical drilling into bone [25][26][27][28][29][30][31][32][33][34][35][36][37][38]. Eeed rate is the linear speed at which the drill bit moves through the bone in the direction of hole creation, which typically ranges from 10 to 132mm/min [26][27][28][29][30]32].…”

“…Eeed rate is the linear speed at which the drill bit moves through the bone in the direction of hole creation, which typically ranges from 10 to 132mm/min [26][27][28][29][30]32]. Spindle speed is the rotational speed of the drill bit around its own long axis, which has ranged from 40 to 3300rpm [26][27][28][29][30]32,33]. Drill bit size is characterized by its major, or outer, diameter, which commonly ranges from 1.98 to 4.76 mm [25][26][27][28][29][30][31][32].…”

“…Spindle speed is the rotational speed of the drill bit around its own long axis, which has ranged from 40 to 3300rpm [26][27][28][29][30]32,33]. Drill bit size is characterized by its major, or outer, diameter, which commonly ranges from 1.98 to 4.76 mm [25][26][27][28][29][30][31][32]. Drill bit type is used to denote the geometric size and shape of the cutting flutes in terms of the clearance angle, helix angle, point angle, rake angle, wedge angle, spiral type, and so on [25,30,37,39].…”

“…Drill bit type is used to denote the geometric size and shape of the cutting flutes in terms of the clearance angle, helix angle, point angle, rake angle, wedge angle, spiral type, and so on [25,30,37,39]. Drilling force, torque, temperature, as well as the quality of the pilot hole and the nature of the bone shavings, are influenced by these and other factors [25][26][27][28][29][30][31][32][33][34][35][36][37][38]. Advances in surgical bone drilling research continue to be made, such as CO2 pulsed laser drilling [40], haptic systems which provide tactile force and torque feedback to the surgeon during drilling [38], and teleoperation in which the surgeon performs the operation from a remote site [41].…”

Estimation of Tool Pose Based on Force–Density Correlation During Robotic Drilling

“…Additionally, a significant body of work exists on the general properties of bone machining [14], [15] and more specifically on the forces and torques observed during the drilling of heterogeneous materials [16], [17]. 0018-9294/$31.00 © 2012 IEEE Fig.…”