Does free-living physical activity improve one-year following total knee arthroplasty in patients with...

Total knee arthroplasty (TKA) is the gold-standard treatment for end-stage knee osteoarthritis, and the primary expectations are reduced pain and improved function. However, there is conflicting evidence regarding functional changes post-TKA. Commonly, functional changes are measured using Oxford Knee Score (OKS). No previous study has investigated physical behaviour (PB) changes in terms of volume and patterns post-TKA. The aims of this study were to explore volume and pattern changes in PB following TKA using an objective tool and to assess the correlation between this and OKS.

An activPAL measured the PB of individuals on a waiting list for TKA for a period of 7-8 days pre-TKA, and for the same length of time at 12 months post-TKA. OKS was completed at similar follow-up time points.

Thirty-three individuals completed the study, where stepping time, the number of steps and the time spent on moderate to vigorous physical activity (MVPA) (>100 steps/minute) improved significantly post-TKA p = 0.0001. Steps at 12 months post-TKA improved by 45.6% (from 4240 to 6174) and stepping time increased by 38.8% (from 0.98 to 1.36 h). MVPA improved by 35 min at 12 months (from 6.6 to 41.7 min). There were no significant correlations between PB and OKS.

This is the first study to explore PB volumes and event-based patterns post-TKA. Activity improved in terms of volume and patterns. No correlation was found between OKS and ActivPAL, which emphasises the need to use objective methods in addition to patient-reported outcome measures.