The reason for depressed scars is because of the dermal layer of the skin and subcutaneous tissue defects, children knocked without stitches depressed scars can be repaired by way of injection filling, but also through surgery and laser methods to repair, the specific choice of methods need to be judged according to the scars left after the child knocked. 1, injection filling: If this kind of depressed scars are not very large, you can fill in the local injection, generally fill the material for hyaluronic acid, which is a relatively effective material for the body generally no adverse effects and harm. The material used for filling is usually hyaluronic acid, which is a relatively effective material and generally has no adverse effects or harm to the body. After filling, the elasticity and cellular activity of the skin can be increased, and the depressed area will become full and alleviate the symptoms of depressed scars; 2.Surgery: For small and shallow depressed scars, the epidermis of the scar can be cut away, and the deep tissue can be retained for filling. The treatment is mainly based on carbon dioxide fractional laser technology, through fractional photothermolysis, heat accumulation in the dermis, minimally invasive treatment area and normal tissue to produce the effect of skin collagen to produce immediate contraction, start the skin trauma repair mechanism, conducive to promoting the reconstruction of the dermal framework structure, improve the depressed scars.