PROJECT SUMMARY Although total knee arthroplasty (TKA) is effective at reducing pain from end-stage osteoarthritis (OA), it is an acute trauma to the joint which exacerbates the underlying weakness and disability common with OA, leading to long-term atrophy and further disability. Attenuation of this acute loss of strength and function can lead to improved long-term outcomes. Key to attenuating this acute loss is effectively managing postoperative knee swelling. Knee swelling after TKA is profound and is theorized to be a major driver of this acute strength and functional loss. This early postoperative strength loss is driven by a deficit in voluntary activation that acutely limits rehabilitation potential and leads to long-term atrophy and disability. Traditional interventions such as elastic compression stockings (e.g., thromboembolism-deterrent [TED] hose) have minimal effectiveness in reducing swelling after TKA. We have demonstrated in a preliminary study that an inelastic, adjustable compression garment can decrease early postoperative swelling by 50%. However, there is a need to formally evaluate the preliminary effects of this garment on all outcomes to inform sample size calculations for a larger trial. Additionally, as a majority of research to date on quadriceps activation and swelling has relied on laboratory induced swelling, this trial will be uniquely positioned to explore in-vivo mechanistic relationships between changes in swelling and quadriceps activation. Therefore, we propose a randomized controlled study of 58 older adult participants undergoing TKA to determine if an inelastic adjustable compression garment (INCOM) improves postoperative swelling more than elastic TED hose (CONTROL). Both groups will wear the assigned garments for the first 3 weeks after TKA and participate in a standardized rehabilitation program after TKA. Outcomes will be assessed preoperatively and postoperatively at weeks 1, 3 (end of garment use),12 and 26. This study will enable us to determine (AIM 1) if INCOM results in improved surgical limb swelling control after TKA (primary outcome) compared to CONTROL and (AIM 2) to explore the preliminary efficacy of INCOM on the outcomes of quadriceps strength, pain, range of motion, physical function, and patient reported outcomes after TKA compared to CONTROL. Additionally, we will explore (EXPLORATORY AIM) the mediating role of swelling on outcomes after TKA. This study has high potential to prevent acute strength and functional losses in the short-term and improve long-term health of the millions of older adults who will undergo TKA annually. This study will uniquely provide insights into 1) causal relationships between swelling and strength/functional outcomes and 2) mechanisms for quadriceps activation deficits. Study findings will also provide insights into the management of numerous other patient populations with significant quadriceps activation deficits (knee OA) or extremity swelling (post-surgic...