MACHINING OF CORTICAL BONE: SURFACE TEXTURE, SURFACE INTEGRITY AND CUTTING FORCES

Abstract

Cutting, drilling and reaming of human bone are conducted in total joint replacement procedures and the placement of dental implants. In the current study orthogonal machining of cortical bone was performed and the cutting and thrust forces, as well as the machined surface quality, were evaluated over a range of osteon orientations and cutting conditions. Results showed that cutting perpendicular to the osteons resulted in the highest machining forces, largest surface roughness and extensive sub-surface damage for some parametric conditions. The average surface roughness of the machined bone ranged from 1 μm to over 70 μm, was largest for positive rake angle tools and increased with the depth of cut. There was no correlation between the cutting forces and machined surface quality. While negative rake angle tools resulted in the largest cutting forces, they provided the lowest surface roughness and highest apparent surface quality. Overall, the results show that orthogonal cutting of bone can result in near-surface damage that reduces the degree of contact between bone and implanted devices and is potentially detrimental to the post-surgical recovery rate.

Keywords:

• Bone
• Cutting
• Surface texture

ACKNOWLEDGMENTS

The authors wish to acknowledge partial support from the Maryland Chapter of the Arthritis Foundation in the form of a new investigator award. The author A. Nazari gratefully acknowledges support from the U.S. Department of Education in the form of a GAANN award.

Notes

¹The specific energy is obtained from the ratio of the average principal cutting force (over the specimen length) to the product of the width and depth of cut [Shaw, 1991].

The authors acknowledge that the work described within this manuscript was supported in part by a grant from the Maryland Chapter of the Arthritis Foundation.