RIBCAGE COMPRESSIBILITY IN LIVING SUBJECTS

The purpose of this study was to examine the responses of normal living subjects to the application of anteroposterior forces to the ribcage. Seventeen subjects aged between 25 and 37 years were tested during slow oscillatory loading while breath-holding at the end of a normal expiration. The mean stiffness coefficient was found to be 9.4 N mm(-1) (SD 2.9) and the mean gradient of the force-strain relation was 1888 N (SD 646). Comparison with previously published cadaver data indicates that the embalmed cadaver ribcage stiffness is in the order of three times stiffer than living subjects, while fresh cadavers showed comparable stiffness to living subjects. A number of studies have used models to predict and understand the behaviour of the thoracic spine. Validation of the behaviour of models which include the thoracic spine and ribcage depends on comparison of model response predictions with observed responses of human subjects. The present study provides data on the anteroposterior compressibility of the ribcage of living subjects which may be suitable for use in model validation studies.