Six minute walk distance or stair negotiation? Choice of activity assessment following total knee replacement

Abstract

Physiotherapists evaluating changing functional performance in patients who have undergone total knee replacement (TKR) will often measure a number of gait-related activities, including six-minute walk distance (6MWD) and the capacity to ascend and descend stairs. In this report, we investigated the correlations between the 6MWD and stair ascent and descent power in a group of patients who had participated in a clinical trial at 2, 8 and 26 weeks post-TKR to establish whether there is redundancy in conducting all three tests. Retrospective analysis of data from a clinical trial was used. One hundred patients (57 female, 43 male) were tested on their 6MWD and power generated and absorbed during stair ascent and descent, respectively. Linear regression modelling was used to determine correlations between pairs of variables at the three measurement intervals. There were consistent relationships between each pair of variables at each measurement interval (r > 0.70; p < 0.001) and also a consistency in the regressions between measurements. The findings indicate that there is no particular benefit to the therapist in measuring more than one of the three variables if the purpose of the measurement is to serve as an indicator of ambulatory functional status for routine clinical assessment.