Knee Body Perception and Pain After Total Knee Arthroplasty

This observational study aims to better understand how knee pain and knee-specific body perception are related over time after total knee arthroplasty (knee replacement) for knee osteoarthritis. Although most people improve after surgery, some continue to experience ongoing pain. Disturbed body perception such as feeling that the knee is less clear, less familiar, or difficult to "sense" or "control" as usual-has been linked to chronic musculoskeletal pain, but the timing of its relationship with postoperative pain after knee replacement is not well understood. Adults undergoing primary total knee arthroplasty at Fukuoka Orthopaedic Hospital will be invited to participate. Participants will be asked to complete brief self-report questionnaires about (1) knee pain intensity during movement, (2) knee pain intensity at rest, and (3) knee-specific body perception (how the knee feels and is perceived). Pain intensity will be recorded using 100-mm visual analogue scales, and knee-specific body perception will be assessed using a validated questionnaire. Questionnaires will be completed before surgery (within one week prior) and at 1, 3, 6, and 12 months after surgery. All surgical and rehabilitation care will be provided as part of usual clinical practice. Participation in this study involves completing questionnaires only and does not change clinical care. The study will examine whether within-person changes in knee body perception are associated with later changes in pain intensity across the first postoperative year, while also accounting for stable differences between individuals. Information from this study may help identify potentially modifiable factors associated with persistent pain after knee replacement and may inform future research on rehabilitation strategies that target body perception and related sensorimotor processes. Study data will be handled confidentially in accordance with institutional policies, and analyses will be conducted on de-identified da