Effect of subperichondrial and supraperichondrial dissection on different cartilage grafts

Septorhinoplasty surgery is a procedure performed for aesthetic or functional purposes. In this surgery, many graft materials are used in the nasal reconstruction phase. Cartilage is a tissue that is widely used as a graft source in septorhinoplasty surgeries. This study on rabbits aims to determine the most effective cartilage dissection plan and selection of the most effective cartilage grafts in septorhinoplasty surgeries by examining the effects of subperichondrial and supra-perichondrial cartilage dissection on intact, diced and crushed cartilage grafts. Fibrosis, viability, inflammation, calcification, bone metaplasia, immature cartilage, basophilia and resorption parameters on the cartilages were examined. In our study, 10 New Zealand rabbits, 5 females and 5 males, aged 22-36 weeks, weighing between 3500 mg and 4000 mg, were used. Cartilage graft material of 3x1 cm, taken from the auricula of the rabbits without perichondrium, was divided into 3 equal parts and prepared as crushed, diced and intact. Crushed, diced and intact cartilage grafts were placed separately into the pockets in which supra-perichondrial dissection was performed on the right ear and into the pockets in which subperichondrial dissection was performed on the left ear. At the end of the 3-month follow-up, the rabbit auricle was excised, and the grafts placed in the perichondrial dissection plans previously determined in the both ears were removed. It was examined histopathologically. During follow-up, 2 rabbits were excluded from the study due to the development of abscesses in their auricle and the study was completed with 8 rabbits. When cartilage graft viability is evaluated; Graft viability of all cartilage types in ears with subperichondrial dissection was found to be higher than in the group with supra-perichondrial dissection. Only the difference between crushed cartilages was not statistically significant. (p>0.05) The effect of subperichondrial dissection on graft viability was statistically significant in diced and intact cartilage graft types. (p<0.05) Cartilage viabilities in the subperichondrial dissection ear were 81% in intact cartilage grafts, 51% in diced cartilage grafts, and 21% in crushed cartilage grafts. In the ear that underwent supra-perichondrial dissection, cartilage viabilities were found to be 61% in intact cartilage grafts, 29% in diced cartilage grafts, and 9% in crushed cartilage grafts.When the grafts were compared with each other in terms of structural differences, both the subperichondrial dissection ear and the supra-perichondrial dissection ear had the highest viability in the intact cartilage grafts, secondarily in the diced cartilage grafts, and the least in the crushed cartilage grafts. Viability differences between all cartilage types in both dissection plans were statistically significant. (p<0.05) It was observed that the rate of bone metaplasia and calcification in the grafts increased as the structural integrity of the cartilage grafts decreased in both subperichondrial and supra-perichondrial dissection planes. With these findings, it can be concluded that the presence of perichondrium in cartilage grafts increases chondrocyte viability and graft viability decreases as the structural integrity of cartilages deteriorates. Therefore, it can be concluded that subperichondrial placement of the grafts to be used in septorhinoplasty operations and minimal disruption of cartilage integrity will positively affect the long-term surgical results. Keywords: subperichondrial dissection, supra-perichondrial dissection, cartilage viability, rhinoplasty