Five randomized controlled trials and one matched cohort study evaluated the effectiveness of continuous passive motion (CPM) after total knee arthroplasty. The studies compared outcomes between groups receiving conventional physical therapy with or without additional CPM treatment. The studies found no significant differences between groups for outcomes including range of motion, function, pain, and length of hospital stay. The studies concluded that CPM provided no additional benefits to patients recovering from total knee arthroplasty beyond conventional physical therapy alone.