Buttocks enhancement with injectable hyaluronic acid. Buttocks enhancement with injectable hyaluronic acid is the easiest and most direct option for filling buttocks, offering a firmer look. The treatment is performed at the clinic, there is no recovery time and the results are immediate and impressive. The hyaluronic acid used is similar to that used for face treatments. Results usually have a duration of over a year. Hyaluronic acid biodegrades slowly, depending on the body’s physiological process. To preserve a satisfactory cosmetic result, a repeat treatment is usually required in 12-14 months. Repeat treatments require smaller hyaluronic acid quantities.