Measurements of walking speeds are commonly used as an objective measure of functional performance in patients with knee osteoarthritis (OA) and are easily performed in a clinical setting. However, the choice in which the walking speed evaluation should be performed is controversial. The aim of this study was to identify the most discriminating walking speed after surgical interventions in patients with knee osteoarthritis, and to compare the responsiveness of the different gait speeds.
A prospective clinical one-year follow-up study involving 54 patients with knee osteoarthritis (63 (+/-5) years of age) who were operated with either a unicompartmental knee arthroplasty or a high tibial osteotomy was undertaken. Thirty-nine patients had unilateral knee OA and 15 patients had bilateral knee OA or other symptoms from the lower extremities that could influence walking. The patients were examined at a gait laboratory before surgery, and one year after surgery. The patients were instructed to walk at slow, normal and fast walking speed.
All patients (n=54) walked.faster one year after the surgical intervention compared to before surgery (p = 0.001) at slow (+15%), normal (+8%) and fast (+7%) walking speed. This increase was similar for the three walking speeds (p = 0.171). Patients with unilateral knee OA (n=39) reached an average change of +0.12 m/s, which was considered clinically important, while patients with bilateral knee OA (n=15) did not increase their walking speed > 0.12 m/s. Effect size was moderate for slow walking speed and small for normal and fast walking speeds, respectively.
The different walking speeds were equally good in detecting changes one year after surgical interventions. In this study, responsiveness favoured slow walking speed, however, the advantages of normal walking speed are discussed.