Prehabilitation Using Aquatic Exercise

With aging population, total knee arthroplasty is performed with increasing frequency. Although the surgery is successful in general, significant number of patients suffers persistent pain and disability. Traditional risk assessment tool have been focused on single organ systems. Our investigators have found that mobility, assessed by the Mobility Assessment Tool short form (MAT-sf), is a simple and accurate method to predict postoperative outcome, including length of stay, postoperative complications, and nursing home placement for older patients. Prehabilitation is the process of enhancing a person's functional capacity to withstand an incoming stressor. Although multiple studies have tested prehabilitation before joint replacement surgery, results have been mixed. The investigators hypothesize that patients with limited mobility are most likely to benefit from prehabilitation. The investigators plan to use individualized aquatic exercise as a prehabilitation tool to enhance compliance; the resistance of water strengthen muscle and increasing energy expenditure; the buoyancy of water provides environment where the joints are not weight bearing. The aims of the study are: 1) To evaluate the feasibility of prehabilitation using 6-8 weeks of aquatic exercise in 40 geriatric patients who are scheduled for total knee arthroplasty for osteoarthritis; 2) To examine the effects of 6-8 weeks of aquatic exercise on mobility, pain, stiffness, physical function, cognitive function and depression; inflammatory markers and 3) To estimate the effect of prehabilitation on postoperative outcomes. The investigators plan to enroll 40 patients age \>50, who are scheduled for elective primary total knee replacement. Investigators will screen patients in the Preoperative Assessment Clinic and enroll patients who have decreased mobility, measured by MAT-sf. Patients will be randomized into either a prehabilitation group or a usual care group. All the participants will undergo extensive