Sj. Eastaugh-waring et al., Fracture stiffness measurement using the orthometer: reproducibility and sources of error, CLIN BIOMEC, 15(2), 2000, pp. 140-142
Objectives. To elicit the reproducibility and the common sources of error i
n the use of the Orthometer, a commercially available goniometer based syst
em, designed to measure the stiffness of healing fractures.
Design. A laboratory based study.
Background. The Orthometer is widely used to measure the progress of fractu
re healing in a quantitative manner. It has been shown previously that the
bending stiffness of a fracture increases with healing and that a stiffness
of 15 Nm/degree equates with the functional union of a tibial fracture.
Methods. The Orthometer was attached in a standard manner to nylon bars of
known stiffness to determine the accuracy of the device. The Orthometer was
then set up with changes in a single positional variable to assess the eff
ect of this variable on the measurement accuracy. A number of different cli
nicians were asked to use the Orthometer before and after a simple training
session and any improvements in the measurement accuracy were observed.
Results. Stiffness could be measured to within 10% or less of the true stif
fness. Markedly different degrees of error were introduced with the various
set-up variables. A simple training session improved clinician accuracy.
Conclusions. Although the Orthometer does allow some degree of safety margi
n, it is essential that set-up is performed carefully, and that the clinici
an has been trained in the use of the device.