Abstract
The present study aims to examine (1) the preoperative factors that can predict postoperative
falls, (2) whether postoperative physical activity (PA) mediates the relationship
between fall incidence and gait function, and (3) whether postoperative PA levels
are associated with fall risk in total knee arthroplasty (TKA) patients. Ninety-six
patients (mean age: 72.0 ± 6.1 years) who were observed postoperatively for 6 months
were selected. Timed up and go (TUG) was assessed as an indicator of gait function.
Fall incidence and PA were investigated for 6 months post-TKA. The body mass index,
history of preoperative falls, knee pain, knee extensor strength, range of motion
in knee flexion, and modified gait efficacy scale were evaluated. Additionally, postoperative
PA levels were categorized into three groups—low: <3,000, moderate: 3,000 to 4,000,
and high: ≥4,000 steps/day. The relative fall incidence rate was calculated according
to the total number of falls normalized for every 1,000 steps/day for 6 months postoperatively.
Twenty-five (26.0%) of the 96 patients had at least one fall. The TUG, knee pain,
and knee extensor strength were identified preoperatively as significant variables
affecting postoperative falls. The mediated effects model revealed that postoperative
fall incidence was predicted by preoperative TUG and postoperative PA. Postoperative
PA was significantly associated with preoperative TUG. Moreover, both the preoperative
TUG and postoperative PA were selected as significant variables for predicting fall
incidence. Thus, postoperative PA mediates the relationship between gait function
and fall incidence after TKA. Furthermore, the relative fall incidence rate associated
with a low PA level was significantly higher than that associated with moderate and
high PA levels. In conclusion, preoperative assessments of TUG performance, muscle
strength, and knee pain were effective in predicting fall risk. Additionally, an increase
in PA could contribute to reducing fall risk in TKA patients. Therefore, our results
suggest that preoperative screening for fall predictors and managing postoperative
PA could reduce the fall incidence in TKA patients.
Keywords
physical activity - fall incidence - gait function - total knee arthroplasty
