Temporal associations between pain intensity and disturbed body perception after total knee arthroplasty: a...

Disturbed body perception is associated with chronic musculoskeletal pain, but its temporal relationship with pain after total knee arthroplasty (TKA) is unclear. We examined whether within-person fluctuations in knee-specific body perception are prospectively associated with pain intensity after TKA, beyond stable between-person differences. A total of 285 people undergoing primary TKA completed the Fremantle Knee Awareness Questionnaire (FreKAQ) and 100-mm visual analogue scales for pain during movement and resting pain preoperatively and at 1, 3, 6 months, and 1 year postoperatively. Random-intercept cross-lagged panel models (RI-CLPMs) were estimated across 5 waves. Model fit was evaluated with the standardized root-mean-square residual (SRMR), comparative fit index (CFI), and root mean square error of approximation (RMSEA). Pain intensity and FreKAQ scores decreased over 1 year. In both RI-CLPMs, higher FreKAQ scores at 6 months were associated with greater pain intensity at 1 year (pain during movement: β = 0.262, P = 0.004; resting pain: β = 0.359, P = 0.003). Resting pain intensity at 3 months was associated with FreKAQ at 6 months (β = 0.179, P = 0.033), whereas no other paths from pain to subsequent FreKAQ scores were significant. Model fit was mixed, with acceptable SRMR and CFI values, but RMSEA values exceeding recommended thresholds. These results highlight a later recovery period warranting further assessment. Disturbed knee-specific body perception at 6 months may be associated with subsequent pain after TKA; however, these observational findings do not establish causality and warrant further longitudinal and interventional research before body-perception-focused rehabilitation can be recommended.