Aims. The purpose of this study was to assess early physical function
after total hip or knee arthroplasty (THA/TKA), and the correlation
between patient-reported outcome measures, physical performance
and actual physical activity (measured by actigraphy). Patients and Methods. A total of 80 patients aged 55 to 80 years undergoing THA or
TKA for osteoarthritis were included in this prospective cohort
study. The main outcome measure was change in patient reported hip
or knee injury and osteoarthritis outcome score (HOOS/KOOS) from
pre-operatively until post-operative day 13 (THA) or 20 (TKA). Secondary measures
were correlations to objectively assessed change in physical performance
(paced-walk, chair-stand, stair-climb tests) at day 14 (THA) or
21 (TKA) and actual physical activity (actigraphy) measured at day
12 and 13 (THA) or 19 and 20 (TKA). . Results. Patients reported improved physical function (HOOS or KOOS) pre-operatively
until day 13 (THA) or 20 (TKA) with a mean difference of 7 (95%
confidence interval (CI) 1 to 13, p = 0.033) and 6 (95% CI 1 to
12, p = 0.033) percentage points, respectively. By contrast, objectively
assessed physical function and activity declined, with no correlations between
subjective and
