Botulinum toxin type A (BTXA) was injected into both sides of the knife edge immediately after operation, the injection volume was 1U/0.1ml per point, the interval between the injection points on the same side of the knife edge was 1cm, and the distance of each injection point from the knife edge was 0.5cm. It was injected only once immediately after operation.

Botulinum toxin type A (BTXA) was injected into both sides of the knife edge immediately after operation, the injection volume was 2.5U/0.1ml per point, the interval between the injection points on the same side of the knife edge was 1cm, and the distance of each injection point from the knife edge was 0.5cm. It was injected only once immediately after operation.

Botulinum toxin type A (BTXA) was injected into both sides of the knife edge immediately after operation, the injection volume was 5U/0.1ml per point, the interval between the injection points on the same side of the knife edge was 1cm, and the distance of each injection point from the knife edge was 0.5cm. It was injected only once immediately after operation.

Injection 0.9%Nacl Immediately after operation 0.9%Nacl was injected on both sides of the knife edge, the injection volume per point was 0.1ml, the interval between each injection point on the same side of the knife edge was 1cm, and each injection point was away from the knife edge 0.5cm. It was injected only once immediately after operation.

Eligible patients were randomly assigned to the experimental group and the control group. Patients in the experimental group will be randomized to receive injections of 1 U,2.5 U, and 5 U botulinum toxin type A,Patients in the control group received an injection of 0.9% Nacl

The mSBSES included width (0 = scar enlargement prominent and > 2 mm, 1 = presence of scar enlargement ≤ 2 mm, 2 = no scar widening), height (0 = marked scar uplift, 1 = presence of scar uplift, 2 = no scar uplift), color (0 = scar significantly redder than surrounding, 1 = scar redder than surrounding and 2 = scar the same color as or lighter than surrounding skin), The visibility of the incision line (0 = marked incision line, 1 = presence of incision line, 2 = absence of incision line) was objectively assessed separately in non-chronological order, with overall scar values varying from 0 to 8, with higher scores indicating better scar appearance.

Patient Satisfaction Scale (1=dissatisfied, 2=slightly satisfied, 3=satisfied, and 4=very satisfied). They were also asked to assess their levels of pain (0=no pain, 1=mild, 2=moderate, 3=severe, 4=very painful) and pruritus (0=no itch, 1=mild, 2=moderate, 3=severe, 4=very itchy) at the incision site. The totals varied between 0-8, where lower scores indicated more positive subjective patient perceptions.