Supporting strength of septal extension grafts

The aim of this study was to measure the supporting strength of septal extension grafts according to the linking methods. Swine scapular cartilages were harvested, and these were cut into pieces measuring 10 × 20 × 2 mm. For the overlapping type, a 4-mm length of each cartilage was overlapped and fixed using 2 interrupted sutures. For the interdigitating type, 2 parallel incisions (5 mm in length) were made 3 mm apart on each cartilage. The tongue of 1 cartilage was slipped into the groove of the other cartilage, and 2 fixation sutures were made. One end of the connected cartilage was gripped with a vise, and a 3-0 silk was passed through the other tip. The degree of sagging of the connected cartilage was measured using micrometers according to the power of a force gauge. The contralateral bending force, the ipsilateral bending force, and the shearing force were measured. In each group, 8 assembled extension grafts were measured and then analyzed with independent sample t-tests.For the contralateral bending force, there was no significant difference between the overlapping type and the interdigitating type (P = 0.494 for 5-mm bending and 0.834 for 10-mm bending). For the ipsilateral bending force, there was also no significant difference between the overlapping type and the interdigitating type (P = 0.247 for 5-mm bending and 0.529 for 10-mm bending). For the shearing force, there was no significant difference between the overlapping type and the interdigitating type (P = 0.495 for 5-mm bending and 0.462 for 10-mm bending). When performing a septal extension graft, the overlapping type is thought to be technically easier than the interdigitating type. Because the bending force and the shearing force are similar for the 2 methods, the easier overlapping type extension graft might be preferred when performing nasal tip surgery.