Abstract
Background: Preoperative physical activity (PA) levels persist in patients following total knee arthroscopy (TKA), despite improved function and mobility following rehabilitation. Long-standing activity behaviors and preexisting psychosocial characteristics may explain suboptimal PA post-TKA. Objective: To (1) confirm latent constructs from outcome measures capturing symptoms, function, psychosocial factors, and mobility and (2) examine relationships between constructs measured pre-TKA and their influence on post-TKA outcomes using factor analyses and structural equation modeling. Design: Secondary analysis of a randomized clinical trial. Setting: Veterans Administration medical center. Patients: U.S. military Veterans (n = 113; age 67.3 +/- 7.3; mean +/- SD; body mass index 29.0 +/- 3.5 kg/m(2); 90% male) scheduled for TKA. Intervention: Participants received TKA postoperative rehabilitation and were randomized to a PA behavior-change intervention targeting increased walking exercise or control group. Main outcome measures: The Western Ontario Measurement Arthritis, Falls Efficacy Scale International, Functional Comorbidity Assessment, Veterans RAND-12 Health Survey, Multidimensional Scale for Perceived Social Support, Geriatric Depression Scale, Self-Efficacy for Exercise scale, Timed-Up and Go, 6-minute walking test, and Life-Space Assessment (LSA) score. Results: A direct relationship was observed between pre-TKA physical characteristics and pre-TKA psychosocial characteristics (beta = .734, z = 7.871, p < .001). Pre-TKA psychosocial characteristics were directly associated with post-TKA LSA scores (beta = -.627, z = 2.924, p = .003). Pre-TKA psychosocial characteristics explained 53.8% of the variability in post-TKA LSA scores and mediated the pre-post relationship between physical characteristics and LSA scores (beta = -0.460, z = -2.455, p = .014). No significant relationship was observed between pre-TKA physical characteristics and post-TKA LSA scores. Conclusions: Latent constructs representing physical health and psychosocial traits were directly related in veterans scheduled for TKA. Elevated psychosocial characteristics observed before TKA were associated with decreased life space mobility at 12 weeks post-TKA. Our findings support addressing psychosocial factors before and throughout TKA rehabilitation as these may have implications on postoperative life space mobility.