The reliability and accuracy of a standard method of tissue compliance assessment.

OBJECTIVE

To assess the reliability and the accuracy of a common method of tissue compliance measurement using a series of non-biological test surfaces (foam). Currently, tissue compliance measurement is most commonly obtained with a hand-held instrument known as a tissue compliance meter (TCM).

DESIGN

Descriptive study.

SETTING

Human Performance Laboratory, University of Calgary.

INTERVENTION

A TCM was tested on four surfaces (three test and one control) with five different input forces resulting in 20 unique surface/force combinations. For each combination of surface/force, ten trials were obtained in a random order by each of five examiners, yielding a total of 1000 separate measurements of surface compliance.

MAIN OUTCOME MEASURE

Millimeters of surface displacement per Newtons of input force.

RESULTS

Intraclass correlation coefficients were calculated for each of the 20 surface/force combinations to judge interexaminer reliability. The median of these 20 coefficients was 0.005: the greatest single value tending toward complete reliability was 0.22. Trials obtained from the control surface (assumed to be incompressible), demonstrated a range of displacements from 0.00 to 2.00 mm.

CONCLUSIONS

Within the design of this experiment, the reliability and accuracy of the hand-held tissue compliance meter was poor. We would suggest that the adequacy of this instrument in clinical practice or scientific work must be seriously questioned. Although the assessment of tissue compliance may be useful in the characterization of the musculoskeletal system and particularly in the assessment of treatment outcome, we surmise that a more reliable and accurate instrument is needed for the quantification of tissue compliance.