Objective:To investigate the rehabilitation-promoting effect of continuous passive motion（CPM）plus aerosol inhalation after knee arthroplasty and analyze the influencing factors for prolonged length of hospital stay. Methods:A retrospective case-control study was performed on 210 patients who had been admitted to our hospital for knee arthroplasty between January 2016 and June 2018. Comparisons were made to determine the significance of differences between the CPM plus aerosol inhalation group and the control group in terms of range of knee motion

Hospital for Special Surgery（HSS）knee score

and incidence rates of hypostatic pneumonia

urinary tract infection

intestinal obstruction

and thrombosis prior to operation

48 h post operation

and at discharge

as well as length of hospital stay. A logistic regression analysis of prolonged length of hospital stay included 300 patients（including the abovementioned 210 patients）who were admitted to our hospital for knee arthroplasty between January2016 and June 2018. Univariate and multivariate logistic regression analyses were performed on 10 clinically potential risk factors such as sex

age

pulmonary infection

urinary tract infection

thrombosis

HSS knee score at discharge

and undesirable wound healing. Results:CPM plus aerosol inhalation significantly increased the range of knee motion

improved knee function score

and reduced the incidence rates of hypostatic pneumonia

urinary tract infection

and thrombosis（P < 0.05）. The risk factors for prolonged length of hospital stay were old age

pulmonary infection

urinary tract infection

thrombosis

low HSS knee score

undesirable wound healing

and diabetes（P <0.05）. Conclusion:CPM plus aerosol inhalation can improve the speed and outcome of postoperative rehabilitation

increase the postoperative range of knee motion and HSS knee score of patients

reduce postoperative complications such as pulmonary infection

urinary tract infection

and thrombosis

and maintain the function of the organs in the body

thus indirectly promoting rehabilitation outcome and shortening the length of hospital stay.