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Proceedings Paper

Development of an optically-based tension-indicating implanted orthopedic screw with a luminescent spectral ruler
Author(s): Nakul Ravikumar; Melissa M. Rogalski; Donny Benza; Joshua Lake; Matthew Urban; Hunter Pelham; Jeffrey N. Anker; John D. DesJardins
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Paper Abstract

An orthopaedic screw was designed with an optical tension-indicator to non-invasively quantify screw tension and monitor the load sharing between the bone and the implant. The screw both applies load to the bone, and measures this load by reporting the strain on the screw. The screw contains a colorimetric optical encoder that converts axial strain into colorimetric changes visible through the head of the screw, or luminescent spectral changes that are detected through tissue. Screws were tested under cyclic mechanical loading to mimic in-vivo conditions to verify the sensitivity, repeatability, and reproducibility of the sensor. In the absence to tissue, color was measured using a digital camera as a function of axial load on a stainless steel cannulated (hollow) orthopedic screw, modified by adding a passive colorimetric strain gauge through the central hole. The sensor was able to quantify clinically-relevant bone healing strains. The sensor exhibited good repeatability and reproducibility but also displayed hysteresis due to the internal mechanics of the screw. The strain indicator was also modified for measurement through tissue by replacing the reflective colorimetric sensor with a low-background X-ray excited optical luminescence signal. Luminescent spectra were acquired through 6 mm of chicken breast tissue. Overall, this research shows feasibility for a unique device which quantifies the strain on an orthopedic screw. Future research will involve reducing hysteresis by changing the mechanism of strain transduction in the screw, miniaturizing the luminescent strain gauge, monitoring bending as well as tension, using alternative luminescent spectral rulers based upon near infrared fluorescence or upconversion luminescence, and application to monitoring changes in pretension and load sharing during bone healing.

Paper Details

Date Published: 18 April 2017
PDF: 12 pages
Proc. SPIE 10081, Frontiers in Biological Detection: From Nanosensors to Systems IX, 100810N (18 April 2017); doi: 10.1117/12.2256052
Show Author Affiliations
Nakul Ravikumar, Clemson Univ. (United States)
Melissa M. Rogalski, Clemson Univ. (United States)
Donny Benza, Clemson Univ. (United States)
Joshua Lake, Clemson Univ. (United States)
Matthew Urban, Clemson Univ. (United States)
Hunter Pelham, Clemson Univ. (United States)
Jeffrey N. Anker, Clemson Univ. (United States)
John D. DesJardins, Clemson Univ. (United States)

Published in SPIE Proceedings Vol. 10081:
Frontiers in Biological Detection: From Nanosensors to Systems IX
Amos Danielli; Benjamin L. Miller; Sharon M. Weiss, Editor(s)

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