Influence of application parameters of ultrasonic-assisted bone instruments on the tear force of a substitute material for spinal dura mater

Marie C. Foelkel 1 , Vitali Herzog 2 , Markus Meier 2  and Michael M. Morlock 3
  • 1 Institute of Biomechanics, Hamburg University of Technology,, Hamburg, Germany
  • 2 Söring GmbH, Justus-von-Liebig- Ring 2,, Quickborn, Germany
  • 3 Institute of Biomechanics, Hamburg University of Technology, Denickestraße 15,, Hamburg, Germany


An ultrasonic-assisted bone instrument can be used for the dissection of bone in spinal surgery. During surgery, the tip of such a bone instrument can touch spinal dura mater. Especially during critical re-operations, high forces can be unintentionally applied on spinal dura mater. To prevent dural tears, the influence of application parameters on the tear force shall be analyzed. Collagen foil is used as a substitute material for spinal dura mater because of its similar mechanical properties and structure. Sponge cloth is placed below collagen foil to imitate cerebrospinal fluid and nerve tissue. A 3-axis CNC-machine is used to automate the movement of the bone instrument. In a full factorial experiment the influence of amplitude, shape of movement and velocity of movement on the tear force is analyzed. Amplitude has the strongest effect because of the increase in input energy. Velocity also has a significant influence, probably because of the strain rate increasing with velocity. Thus, a surgeon should mainly reduce the amplitude and furthermore the velocity of movement to generate higher safety in critical areas.

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Current Directions in Biomedical Engineering is an open access journal and closely related to the journal Biomedical Engineering - Biomedizinische Technik. CDBME is a forum for the exchange of knowledge in the fields of biomedical engineering, medical information technology and biotechnology/bioengineering for medicine and addresses engineers, natural scientists, and clinicians working in research, industry, or clinical practice.