A feasibility study on using external microphone measurements for reconstructing in vivo interskeletal forces

Abstract

While there is much interest in the measurement of forces within the skeleton during human movement, the need for in vivo sensors makes measuring these forces challenging. This study investigates the feasibility of using a non-invasive external measurement technique utilizing microphones on the surface of human skin to enable characterization of impulse forces propagating through bone structures. The challenge lies in the ability to measure pressure waves that propagate through complex human tissue. A simplified anatomical model of a human leg is examined with a hollow metal bar representative of a simplified bone structure and a coupled homogeneous ballistic gel to represent the muscular and integumentary systems. In the experimental tests, an impulse force was applied to the bar with an impact hammer, and surface-mounted microphones were used to measure the signal generated on the surface of the ballistics gel. Feasibility of this measurement technique for inferring forces will be determined by examining the quality of the measured acoustic signal resulting from coupled vibrations of the bar and gel structure. An objective of the study is to ensure that the measured acoustic signal has sufficient quality to be useable in reconstructing the impulse forces acting on bones via inverse methods.While there is much interest in the measurement of forces within the skeleton during human movement, the need for in vivo sensors makes measuring these forces challenging. This study investigates the feasibility of using a non-invasive external measurement technique utilizing microphones on the surface of human skin to enable characterization of impulse forces propagating through bone structures. The challenge lies in the ability to measure pressure waves that propagate through complex human tissue. A simplified anatomical model of a human leg is examined with a hollow metal bar representative of a simplified bone structure and a coupled homogeneous ballistic gel to represent the muscular and integumentary systems. In the experimental tests, an impulse force was applied to the bar with an impact hammer, and surface-mounted microphones were used to measure the signal generated on the surface of the ballistics gel. Feasibility of this measurement technique for inferring forces will be determined by examinin...