An apparatus and method are disclosed for noninvasively diagnosing limb compartment syndrome by measuring a quantitative modulus of hardness. In the preferred embodiment, a low friction piston probe mounted within a platform is applied against a limb compartment. Pressure within the piston probe is increased while measuring the displacement of the piston plunger for each pressure applied. The relationship of incremental pressures in the piston to the displacements of the piston plunger are plotted and a linear regression analysis is performed whose slope forms a quantitative modulus of hardness. In an alternate, completely automated, continuous embodiment, a circumferential cuff secures the piston probe mounted within the a platform against the limb compartment, while the quantitative hardness modulus is formulated.