Obstacle avoidance in persons with rheumatoid arthritis walking on a treadmill.

OBJECTIVE Patients with rheumatoid arthritis (RA) are at increased risk of falling. In healthy elderly persons with a history of falling, a reduced ability to avoid obstacles while walking has been shown to relate to increased fall risk. The aim of this study was to determine whether this potential risk factor for falls would also be present in persons with RA. METHODS Twelve RA patients and twelve controls performed an obstacle avoidance task on a treadmill. The obstacle was released during three different phases of the gait cycle (late stance, early swing and mid swing) to create increasing difficulty levels. The primary outcome measure was failure rate. RESULTS Overall, the RA patients had significantly higher obstacle avoidance failure rates. To avoid an obstacle, a long or a short stride strategy can be used, the choice of which depends on the phase of obstacle release. There were no significant group differences in the distribution of obstacle avoidance strategies. However, the RA patients made significantly more failures when performing a short stride strategy in mid swing obstacle release trials (the condition which gave the patients the least time to react; available response time). In addition, compared to the controls, the RA group approached the obstacle more closely prior to obstacle crossing (shorter toe distance), thereby increasing the risk of stumbling. CONCLUSION Obstacle avoidance performance in persons with RA is significantly deteriorated compared to age- and gender-matched controls, especially when available response time is low. This deficit may contribute to their higher fall risk.