BIORHEOLOGICAL FEATURES OF SOME SOFT-TISSUES UNDER A SURGICAL TISSUE EXPANSION PROCEDURE

The aim of this study was to investigate the effects of a surgical tis sue expansion procedure on the biomechanical features of the expanded soft tissues, In this procedure a silicone balloon ''expander'' is sur gically inserted into a tissue and inflated, The tissue mass increases under the stretch of the expander. The increased tissue can then be u sed as an autologous source for the surgical reconstruction of organs. In this article, dog saphenous neurovascular bundle was used. Expande d saphenous nerves, arteries and veins were harvested and their biomec hanical features and ultrastructural, histological changes were studie d, The stress relaxation features, the continuous spectrum of relaxati on time, and the stress-strain relationship of expanded and control sp ecimens were measured, Results show that within two or three weeks aft er placement of the expanders, the biomechanical properties of expande d saphenous nerves, arteries and veins began to deviate from those of their controls, and the differences between them were proportional to the volume of inflation; but when the expanding period was 15 weeks or longer, the properties of expanded specimens and their controls becam e close again, Histological study showed that the content of collageno us fibers in blood vessel walls decreased after expansion, The content of elastic fibers in blood vessel walls first increased, then returne d to normal, and finally decreased, Ultrastructural studies showed tha t when elongated by 25-40%, the expanded nerves had well preserved axo ns and showed fewer smooth myelin sheaths only in the middle and dista l part of the expansion, (C) 1997 Elsevier Science Ltd.