Upright Magnetic Resonance Imaging Tasks in the Knee Osteoarthritis Population: Relationships Between Knee Flexion Angle, Self-Reported Pain, and Performance

• Individuals with symptomatic knee osteoarthritis (OA) were studied in a laboratory setting while they performed flexed knee standing tasks used in static, upright weight-bearing magnetic resonance imaging (MRI) scans.
• Biofeedback of the knee flexion angle was provided by an MRI–compatible sensing system, and a sequence of target angles was presented.
• Increasing self-reported knee pain was significantly associated with shorter durations over which the task was performed successfully, as defined by a maximum error tolerance on knee flexion.
• The study provided evidence that weight-bearing MRI evaluations based on imaging protocols in the range of 2 to 3 minutes are compatible with patients reporting mild to moderate knee OA-related pain.

ObjectiveTo characterize the ability of patients with symptomatic knee osteoarthritis (OA) to perform a weight-bearing activity compatible with upright magnetic resonance imaging (MRI) scanning and how this ability is affected by knee pain symptoms and flexion angles.DesignCross-sectional observational study assessing effects of knee flexion angle, pain level, and study sequence on accuracy and duration of performing a task used in weight-bearing MRI evaluation. Visual feedback of knee position from an MRI compatible sensor was provided. Pain levels were self-reported on a standardized scale.SettingSimulated MRI setup in a research laboratory.ParticipantsConvenience sample of individuals (N=14; 9 women, 5 men; mean, 69±14y) with symptomatic knee OA.InterventionsNot applicable.Main Outcome MeasuresAveraged absolute and signed angle error from target knee flexion for each minute of trial and duration tolerance (the duration that subjects maintained position within a prescribed error threshold).ResultsAbsolute targeting error increased at longer trial durations (P<.001). Duration tolerance decreased with increasing pain (mean ± SE, no pain: 3min 19s±11s; severe pain: 1min 49s±23s; P=.008). Study sequence affected duration tolerance (first knee: 3min 5s±9.1s; second knee: 2min 19s±9.7s; P=.015).ConclusionsThe study provided evidence that weight-bearing MRI evaluations based on imaging protocols in the range of 2 to 3 minutes are compatible with patients reporting mild to moderate knee OA-related pain.