Impact of Tissue Handling and Size Modification on Septal Chondrocyte Viability

Introduction: The physical modification of cartilage grafts during rhinoplasty risks chondrocyte death at the margins where the tissue is cut. This study compares chondrocyte viability between diced, scaled, and pate samples in human models, and further computes percent chondrocyte viability as a function of sequential dicing size in a computational model. Methods: Septal cartilage from 11 individuals was prepared as follows: diced (1 mm cubic), scaled (shaved to <1 mm thickness similar to translucent), pate (0.02 g of scraped cartilage surface), positive control (2 x 2 mm diced), and negative control (2 x 2 mm diced soaked in 70% EtOH). Viability analysis was performed using Live/Dead assay (TM) and confocal microscopy. Numerical simulation of cartilage dicing in 0.05 mm increments was performed using MATLAB assuming 250 chondrocytes/mm(3) with each average chondrocyte size of 65 mu m(2). Results: Chondrocyte viability was similar between 1 mm diced cartilage, scaled cartilage, and positive control samples (p > 0.05). Conversely, pate samples had significantly less viability compared to positive controls, diced samples, and scaled samples (all p < 0.01 after Bonferroni correction). Pate samples had similar chondrocyte viability compared to negative controls (p = 0.36). On computational modeling, cartilage viability decreased to 50% as the diced sample was cut from 1 mm edge length to 0.7-0.8 mm. Similarly, cartilage viability decreased to 26% at 0.55-0.65 mm, 11% at 0.4-0.5 mm, and <5% at <0.4 mm edge length. Conclusion: Modifying septal cartilage grafts into 1 mm diced or scaled samples maintains ideal chondrocyte viability whereas pate preparations result in significant chondrocyte death. According to computational analysis, chondrocyte viability sharply decreases as the cartilage is diced below 0.7-0.8 mm.