Heinz Koelbl led the peer-review process as the Associate Editor responsible for the paper.
An automated hand-held elastometer for quantifying the passive stiffness of the levator ani muscle in women
Article first published online: 27 NOV 2013
© 2013 Wiley Periodicals, Inc.
Neurourology and Urodynamics
Volume 34, Issue 2, pages 133–138, February 2015
How to Cite
Kruger, J. A., Nielsen, P. M.F., Budgett, S. C. and Taberner, A. J. (2015), An automated hand-held elastometer for quantifying the passive stiffness of the levator ani muscle in women. Neurourol. Urodyn., 34: 133–138. doi: 10.1002/nau.22537
Conflict of interest: none.
- Issue published online: 11 FEB 2015
- Article first published online: 27 NOV 2013
- Manuscript Accepted: 25 SEP 2013
- Manuscript Received: 3 JUL 2013
- Aotearoa Postdoctoral Research Fellowship
- levator ani muscles;
- passive stiffness;
- pelvic floor
Design and develop an automated, hand-held instrument (elastometer) to assess in vivo passive stiffness of the pelvic floor muscle.
Materials and Methods
The elastometer system consisted of a hand piece, real-time controller, and laptop computer. A cable connected the hand-piece to the controller, which communicated with a laptop computer via an ethernet connection. Force sensitivity calibration and displacement accuracy were determined experimentally using a spring load and an Instron mechanical tester. A test re-test series quantified the in vivo repeatability (within a procedure) and reproducibility (between procedures after a 5 min delay) of passive stiffness in volunteers (n = 20). Stiffness was determined from the gradient of the force–displacement curve for each cycle.
The force-aperture spring measurements from the elastometer showed consistent (r2 = 1.0000) agreement with those measured by the Instron. The difference between spring stiffness as measured by the elastometer and the Instron (388.1 N/m cf. 388.5 N/m, respectively) was negligible. The intra-class correlation coefficient for repeatability within procedures was 0.986 95% CI (0.964–0.994) n = 20, and reproducibility between procedures ICC 0.934 (95% CI 0.779–0.981) n = 12. Bland–Altman analysis determined a bias of 0.3 and 18.5 N/m, for repeatability and reproducibility respectively. Neither bias is likely to be clinically significance.
The elastometer demonstrated very good repeatability and accuracy in the measurement of force/displacement during in vitro testing. There was a high degree of repeatability and reproducibility in stiffness measurements in a test re-test series. Our results demonstrate the elastometer is accurate and reliable and thereby suitable for larger clinical trials. Neurourol. Urodynam. 34:133–138, 2015. © 2013 Wiley Periodicals, Inc.