Adhesion of the knee is a major concern after knee surgery, the treatment of which is difficult. Botulinum toxin A (BTX-A) injection is demonstrated as efficient in treating knee adhesion after surgery. However, the treatment outcomes and the mechanism of action are not yet determined. The formation of adhesion in the knee is a common complication after knee surgery. The rate of arthrofibrosis following total knee arthroplasty (TKA) is estimated to be 8-12% and the rate after ligament reconstruction is 0-4%, and it is up to 7% following a fracture of the tibial plateau high-energy fractures. Arthrofibrosis of the knee leads to stiffness, a decreased range of motion and pain. The loss of range of motion of the knee impairs the nutrition supply to the cartilage, resulting in cartilage degeneration and, eventually, loss of function in the knee. A range of motion of the knee from 0 to 125° is adequate for activities of daily living for people. A loss of extension of 5° in the knee joint significantly increases the energy consumption of the quadriceps muscle and produces a limp.