World Congress on Osteoarthritis location:Philadelphia, USA date:18-21 April 2013
Purpose: Subjects with knee osteoarthritis have demonstrated an impaired ability to ascend and descend stairs, movements that load the knee joint more forcefully than gait. The knee joint kinetics and kinematics during stair negotiation in knee osteoarthritic subjects have however received little attention so far. The aim of this study was therefore to evaluate stair climbing in women with medial knee osteoarthritis.
Methods: Eight subjects with symptomatic mild unilateral knee OA (Kellgren-Lawrence score 1) and 8 persons with symptomatic moderate knee osteoarthritis (Kellgren-Lawrence scores 2-3) were compared with 8 healthy control subjects (mean age: 64.29 years). Stair negotiation was performed bare feet on a 20 cm single stair without support. Subjects performed 3 trials of stair ascent and 3 of stair descent at their self-selected speed. A 3D motion analysis system (Krypton) combined with force plates (Bertec) were used to capture the movements. Kinematic and kinetic data were processed using Opensim. The data were normalized over time and joint moments were further normalized with body weight. Results on knee kinematics and kinetics of the affected leg during single leg support phase were the main focus. All parameters assessed were compared between mild and moderate OA patients and control subjects using Kruskal–Wallis one-way analysis of variance.
In stair ascent, patients with moderate OA showed a decreased external knee flexion moment during initial contact (IC) (p<0.05) and an increased peak and average knee external adduction moment (KAM) during single leg stance compared to healthy controls (p<0.05).
In stair descent, patients with moderate OA showed an increased maximum knee adduction angle during single leg stance (p<0.01) and an increased peak external knee adduction moment (KAM) compared to healthy controls (p<0.05).
Conclusion: The results of this study showed that altered knee joint loading is present both during stair ascent and descent in subjects with moderate knee OA but not in subjects with mild symptomatic OA. On one hand, the decreased external knee flexion moment during stair ascent shows that subjects with moderate OA show the intent to minimize knee joint loading and decrease the demand on the quadriceps muscles. On the other hand, the increased KAM during stair ascent and descent points towards a remaining increased load on the medial compartment of tibia and must be seen as a risk factor for further progression of knee OA. Further study of the alterations and compensations that OA patients use during stair negotiation might be useful to determine target points for rehabilitation.