Summary

Our study using a wearable physical monitor demonstrated that adequate preoperative flexion muscle strength has a significant impact on moderate physical activity levels immediately after total knee arthroplasty.

Abstract

Background

The evaluation of clinical outcomes in total knee arthroplasty (TKA) has traditionally focused on radiographic assessments and patient-reported outcome measures (PROMs). However, it remains unclear whether these results enable surgeons to accurately assess a patient’s actual improvement in daily life activities. The aim of this study is to investigate the relationship between preoperative factors and a patient’s actual daily movement as evaluated using a wearable physical monitor (WPM), and to identify factors associated with improvements in daily life activities following TKA.

Methods

Thirty patients with end-stage knee osteoarthritis underwent unilateral TKA. Preoperative assessments included skeletal muscle index (SMI) and knee muscle strength. Additionally, daily physical activity was monitored using a wearable physical activity monitor for one month both preoperatively and postoperatively (6–10 weeks after TKA). The monitor recorded daily steps count, and the average daily time spent in physical activities at different metabolic equivalent (MET) levels. Correlations and multiple regression analyses were performed.

Results

Pre- and postoperative moderate-to-vigorous physical activity (MVPA, ≥3.0 METs) durations were significantly correlated (p < .0001). Preoperative contralateral knee flexion strength was significantly associated with 4.0–4.9 MET activity postoperatively in multiple regression analyses (p = 0.01).

Conclusion

Preoperative MVPA and contralateral knee flexion strength are important predictors of early postoperative physical activity after TKA.