Table 1 Key inclusion and exclusion criteria

Patients underwent primary unilateral total knee replacement

Mental disorder

Age between 50 and 75 years

Drug dependence and drug abuse

Informed and willing to participate in the study

Unconscious and have difficulty in expressing pain by a NRS

Without any postoperative complication

Epilepsy, pulmonary embolism, intestinal obstruction, aerothorax

Recent worst pain (during functional exercise) reported to be 4 or higher (on a Numerical Rating Scale (NRS) of 0 to 10)

Disease involving ear, nose, larynx, such as sinuses, otitis media