Falls are the most common cause for injury-related hospitalization in older adults and account for over $50 billion per year in medical costs. For the ~27% of US adults with symptomatic osteoarthritis (OA) the odds of falling are up to 54% higher than for people without OA. The high incidence of falls associated with OA remains high after total knee arthroplasty (TKA). The incidence of falls during the first year after TKA is up to 51.8%. With over 750,000 TKAs performed annually, the scope of the problem is large. Despite several calls in the literature for new methods to decrease fall rate after TKA, there are, to our knowledge, no such interventions specifically targeting this group. Our recent work, however, demonstrates the promise of perturbation training in knee OA. We have established that limiting trunk angle and angular velocity during the initial recovery step after a disturbance, such as a trip, is a critical factor in avoiding a fall. This motor skill can be improved through task-specific perturbation training. In our pilot study, trip-specific perturbation training effectively improved trunk kinematics during the initial recovery step after a trip-simulating perturbation in women with moderately symptomatic OA. Further, we have shown that trip-specific perturbation-training reduces fall-rates in the community in healthy older women. Building on this past success, our long-term goal is to reduce the incidence of preventable gait-related falls by older adults with joint replacements. The objective of this application is to establish that preoperative task-specific training of stepping responses to sagittal and frontal plane disturbances reduces the risk of postoperative falls in people undergoing TKA. Our central hypothesis is that individualized preoperative sagittal and frontal plane perturbation training will significantly reduce postoperative fall rates in people scheduled for TKA by improving trunk kinematics during the initial recovery step. To test this hypothesis, we will evaluate preoperative TKA patients, randomized into either a perturbation-training group or a conventional fall-prevention education group. We will assess our central hypothesis through two aims. Aim 1: Demonstrate the extent to which perturbation training focused on forward and laterally directed stepping responses improves recovery step trunk mechanics in preoperative TKA patients. Aim 2: Demonstrate the effectiveness of forward and laterally directed perturbation training in reducing incidence of preventable gait- related falls for one year after TKA. With extensive collective expertise in OA and arthroplasty gait mechanics, aging, falls, and fall-prevention, including clinical trial experience, we are well poised to accomplish these aims. Further, through our innovative prehabilitation approach, we will, for the first time, address both trip-specific and laterally directed falls in this patient population. In addition, this study will advance our mechanis...