Influence of loading rate and cable migration on fiberoptic measurement of tendon force

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Several investigators have recently used fiberoptic cables to measure tendon forces in situ. The technique may be subject to significant error due to cable migration and differences in the loading rates used for calibration and those experienced during measurement. This in vitro study examined the impact of these potential sources of error on transducer accuracy. A fiberoptic cable was passed perpendicular to the fibers of four Achilles tendons in the mediolateral direction and each specimen was cyclically loaded to 1000 N. The influence of loading rate on transducer output was investigated by comparing results from tests conducted at 20, 200 and 1000 N/s. The effect of cable migration was examined by comparing the outputs obtained after displacing the cable one tendon width medially and laterally along its path in the tendon and then repeating the 200 N/s testing protocol. It was possible to obtain nonlinear specimen-specific relationships between the fiberoptic output and tendon force. Differences in loading rate resulted in root-mean-square (RMS) errors not larger than 17% maximum load. Hysteresis effects caused RMS errors smaller than 5% maximum load. Cable migration errors were less than 27%. The total RMS error due to the combined effects of loading rate difference and cable movement was less than 32%. Fiberoptic measurement of tendon force is attractive due to its low cost, easy implementation and comparable accuracy relative to other implantable force transducers. Although additional factors such as cable placement, edge artifacts due where the transducer exits the skin and non-uniform loading may also influence fiberoptic output, careful control of loading rate and transducer movement during calibration is imperative if maximum accuracy is to be achieved.

Original languageEnglish (US)
Pages (from-to)857-862
Number of pages6
JournalJournal of Biomechanics
Volume35
Issue number6
DOIs
StatePublished - May 27 2002

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Tendons
Transducers
Cables
Calibration
Mean square error
Achilles Tendon
Artifacts
Research Design
Research Personnel
Costs and Cost Analysis
Skin
Hysteresis
Fibers
Testing

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Orthopedics and Sports Medicine
  • Biomedical Engineering
  • Rehabilitation

Cite this

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title = "Influence of loading rate and cable migration on fiberoptic measurement of tendon force",
abstract = "Several investigators have recently used fiberoptic cables to measure tendon forces in situ. The technique may be subject to significant error due to cable migration and differences in the loading rates used for calibration and those experienced during measurement. This in vitro study examined the impact of these potential sources of error on transducer accuracy. A fiberoptic cable was passed perpendicular to the fibers of four Achilles tendons in the mediolateral direction and each specimen was cyclically loaded to 1000 N. The influence of loading rate on transducer output was investigated by comparing results from tests conducted at 20, 200 and 1000 N/s. The effect of cable migration was examined by comparing the outputs obtained after displacing the cable one tendon width medially and laterally along its path in the tendon and then repeating the 200 N/s testing protocol. It was possible to obtain nonlinear specimen-specific relationships between the fiberoptic output and tendon force. Differences in loading rate resulted in root-mean-square (RMS) errors not larger than 17{\%} maximum load. Hysteresis effects caused RMS errors smaller than 5{\%} maximum load. Cable migration errors were less than 27{\%}. The total RMS error due to the combined effects of loading rate difference and cable movement was less than 32{\%}. Fiberoptic measurement of tendon force is attractive due to its low cost, easy implementation and comparable accuracy relative to other implantable force transducers. Although additional factors such as cable placement, edge artifacts due where the transducer exits the skin and non-uniform loading may also influence fiberoptic output, careful control of loading rate and transducer movement during calibration is imperative if maximum accuracy is to be achieved.",
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Influence of loading rate and cable migration on fiberoptic measurement of tendon force. / Erdemir, Ahmet; Piazza, Stephen Jacob; Sharkey, Neil.

In: Journal of Biomechanics, Vol. 35, No. 6, 27.05.2002, p. 857-862.

Research output: Contribution to journalArticle

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