Experimental and computational analysis of soft tissue mechanical response under negative pressure in forearm.

Background: Instrumentation, relying on the use of negative pressure (suction), has been introduced to reduce pathological tissue swelling. Then, relative contribution of skin, adipose tissue and muscle, to the overall mechanical response is not known.

Methods: Under suction, stretch of soft tissues in the forearm of human subjects (N = 11) was experimentally measured at rest and under venous occlusion. Three dimensional, fibril-reinforced hyperelastic finite element (FE) model was constructed, the model response was matched with the experimental measurement and the mechanical characteristics of each tissue were derived. Parametric analyses were conducted to evaluate the impact of different tissues on the total stretch.

Results: The model suggested that, at large strains, the stretch response was more sensitive to changes in the elastic modulus of skin than those in adipose tissue. During venous occlusion, reduction of the stretch of forearm tissues was related to stiffening of the skin and adipose tissue, as evidenced by increased modulus of 27 ± 21% and 35 ± 26%, respectively.

Conclusion: The method based on suction may be used to diagnose and monitor changes in properties of soft tissues, especially those of skin, as well as tissue swelling typical to pathological conditions such as oedema.