UC Irvine

Objectives/hypothesis

Determine the effective electromechanical reshaping (EMR) parameters for shape change and cell viability in the ex vivo rabbit costal cartilage model.

Study design

Ex vivo animal study combined with computer modeling to guide electrode placement and polarity selection.

Methods

Rabbit costal cartilages were secured in a jig that approximated the shape of the rabbit auricle framework. Finite element modeling was used to select the initial electrode geometry, polarity, spacing, and estimate dosimetry parameters. Porcine costal cartilage was utilized to refine the selection of dosing parameters. Parametric analysis was performed to determine the effect of voltage and application time on tissue shape change. Next, rabbit rib cartilage was reshaped, varying voltage and application time to identify the lowest parameters to produce acceptable shape change mimicking native auricular cartilage. Acceptable qualitative shape change was determined on a five-point Likert scale analyzed using one-way general linear analysis of variance. Confocal microscopy with live/dead cell viability analysis determined the degree of injury and the distribution of live and dead cells.

Results

The minimum acceptable deformation of rabbit costal cartilage was found at 4 V-3 minutes. Viability analysis of cartilage reshaped at 4 V-3 minutes demonstrates cell injury extending 2 mm away from each electrode with viable cells found between the electrodes.

Conclusions

The EMR parameters of 4 V-3 minutes demonstrates appropriate shape change producing grafts that resemble the native auricle and contains the viable cells adequate for clinical evaluation. The rabbit auricular reconstruction model using EMR is a feasible one.