Quantifying frontal plane knee thrust in patients with medial knee osteoarthritis using weight transfer and balance tasks.

BACKGROUND

Frontal plane instability and chronic pain are common, particularly in older adults with knee osteoarthritis. Previous literature has quantified frontal plane knee thrusts (varus or valgus) during gait, but not during a balance task. This may be relevant to the clinical assessment of people with knee problems, as for some, gait may be too impaired for analysis. The present study aimed to determine the relevance of the proposed measures of knee thrust assessed during a weight transfer and balance task. We hypothesised that the knee thrusts quantified would be sensitive to the presence and severity of osteoarthritis and have high repeatability between trials, which is critical for patient monitoring.

METHODS

Forty-nine older adults (mean 63.8 ± 7.4 years) with (n = 33) or without (n = 16) knee osteoarthritis performed a total of six frontal plane weight-bearing transfer trials in a single-leg standing task. Motion analysis, performed using a non-invasive exoskeleton setup and optoelectronics, focused on the frontal plane knee angles at specific timepoints during the task to extract varus-valgus thrust measures and their magnitude (absolute values). The sensitivity of the measures to the presence and severity of knee osteoarthritis and their repeatability between trials were determined. Correlations between the relevant thrust measures, frontal plane range of motion and the WOMAC pain, function, and stiffness subscales were also computed.

RESULTS

Results show that the |Peak-2 %BW| measure of thrust (absolute values) is sensitive to disease and its severity and has high repeatability between trials. The Peak-2 %BW measure (in varus/valgus direction) was significantly correlated with the WOMAC function and stiffness subscales.

SIGNIFICANCE: This study highlights that a weight transfer and balance task is effective in quantifying frontal thrusts in knee osteoarthritis. Both relative and absolute measures may be relevant for clinical follow-up.