Mechanistic Understanding of Tissue-Plane Adaptability in Cohesive Polydensified Matrix Hyaluronic Acid Gels Intense and Volume

BACKGROUND Hyaluronic acid (HA) gel behavior depends on material properties, injection technique, implantation depth, and tissue biomechanics. Despite similar HA concentrations and overlapping clinical indications, cohesive polydensified matrix (CPM) gels CPM-I and CPM-V exhibit distinct tissue-plane–dependent projection profiles. OBJECTIVE The aim of this study was to determine whether differences in tissue-plane adaptability between CPM-I and CPM-V are explained by differences in their mechanical behavior under clinically relevant loading conditions. MATERIALS AND METHODS Standardized 100-μL injections of CPM-I and CPM-V were performed in a synthetic tissue model at subdermal and deep implantation depths. Bolus morphology was quantified by 3-dimensional morphometric analysis. Material behavior was characterized using linear and nonlinear oscillatory rheology, compression testing, and extrusion force measurements. RESULTS CPM-I demonstrated greater depth-dependent changes than CPM-V. Deep implantation reduced projection height and bolus volume by 12% and 11% for CPM-I versus 6% and 2% for CPM-V. CPM-I also exhibited greater lateral spread, greater strain to flow, and approximately two-fold higher extrusion force, whereas CPM-V demonstrated greater elastic stiffness. Compression end points were similar. CONCLUSION Despite similar HA concentrations, CPM-I and CPM-V exhibit distinct mechanical and morphometric behaviors. Differences under nonlinear deformation and pressure-driven flow suggest that manufacturing-derived polymer architecture influences tissue-plane adaptability and may support filler selection according to tissue biomechanics.