Reduced functional performance is a risk factor for development of knee osteoarthritis, and peak knee adduction moment is associated with radiographic progression. Knee adduction moment can be reduced by high tibial osteotomy. The effect of dynamic stabilization through increased muscle performance is not known.
To study the effect from exercise on external peak knee adduction moment during one-leg rise, and the relationship between peak knee adduction moment during one-leg rise and maximum number of one-leg rise.
13 patients, aged 48–63, with mild to moderate knee osteoarthritis underwent 8 weeks of supervised exercise, aiming at increasing neuromuscular control and lower extremity strength. The maximum number of one-leg rise from a stool (48 cm), 3-dimensional gait analysis and self-estimated knee symptoms were assessed before and after exercise intervention. Peak external knee adduction moment during one-leg rise and gait was calculated using a Vicon system. The Knee injury and Osteoarthritis Outcome Score (KOOS) was used as assessment of knee symptoms. Patients defined their most symptomatic knee as index knee.
Peak knee adduction moment during one-leg rise was reduced for the index knee from 0.57 Nm/kg at baseline to 0.51 after 8 weeks of exercise (p=0.04). The change for the opposite knee was not significant (from 0.58 to 0.56 Nm/kg, p=0.23). No significant changes were seen for index or opposite knees in peak adduction moment during gait (p>0.40). A higher maximum number of one-leg rise was correlated to a lower peak adduction moment for the index knee at baseline (rs =-0.35, p=0.24) and follow up (rs = -0.65, p=0.03). For the opposite knee the correlation was similar at baseline (rs= -0.47, p=0.10), and no correlation was seen at follow up (rs = 0.13, p=0.70). Correlations for change over time were poor (-0.43 to -0.03) and not significant (p>0.20). Patients with symptomatic knee osteoarthritis had higher peak adduction moment in their opposite knee, than patients without symptoms at baseline (0.72 (0.09) vs. 0.50 (0.11), p=0.01) and follow-up (0.66 (0.14) vs. 0.51 (0.07), p=0.04). The differences for the index knee pointed in the same direction, however not significant (p>0.28).
Peak knee adduction moment in the most symptomatic knee of middle-aged patients with early signs of knee osteoarthritis can be reduced by exercise. Improved muscular performance might reduce the risk of radiographic progression of knee osteoarthritis. It seem of importance to reduce pain prior to starting exercising. A lower maximum number of one-leg rise is associated with higher peak knee adduction moment and has the potential to serve as a surrogate in studies where 3-dimensional analysis is not feasible.
Manuskript i avhandling. Manuscript in dissertation.