Quantitative muscle hardness as a noninvasive means for detecting patients at risk of compartment syndromes.

The purpose of this project was to study the efficacy of quantitative muscle hardness (QH) curve analysis for noninvasive measurement of muscle compartment interstitial pressure (IMP), and to eliminate the need for a comparison normal QH measurement to determine a pathologic reading. Elevation of IMP may lead to limb compartment syndrome, which may result in irreversible dysfunction, chronic pain and contracture. Two studies were performed by two separate independent examiners on male volunteers, where IMP measurements and QH curves were obtained. QH curves were divided into three parts comparing the third part to the second part using the coefficient of determination (R(2)). In 205 limb compartments, there were 1432 comparison readings of the IMP versus R(2). Using receiver operator characteristic curve analysis for all data from both studies, an R(2) cutoff of 0.974 best corresponded to a pathologic IMP of 50 mmHg. For both sets of data and for each compartment tested, the mean IMP values were statistically different (t-test: P < 0.0001) for the group with R(2) values less than 0.974 compared to the group of R(2) values greater than or equal to 0.974. In addition, a pressure prediction model was formulated with a strong overall correlation coefficient of 0.78. The data of this study support that QH analysis is potentially useful for the monitoring of IMP elevation in compartment syndrome.