THE EFFECT OF PHARMACOLOGIC THERAPY ON KINETIC GAIT PARAMETERS IN PATIENTS WITH PERIPHERAL ARTERIAL DISEASE Jessie M. Huisinga 1 , Sara A. Myers 1 , Jason M. Johanning 2,3 , Iraklis Pipinos 2,3 , and Shing-Jye Chen 1 1 University of Nebraska at Omaha 2 University of Nebraska Medical Center 3 Veterans Affairs Medical Center, Omaha, NE E-mail: jhuisinga@mail.unomaha.edu Web: www.unocoe.unomaha.edu/hper/bio/home.htm INTRODUCTION Peripheral Arterial Disease (PAD) is a manifestation of atherosclerosis of the leg arteries that affects 10 million people in USA (Antignani, 2003). For these people, walking is a difficult task because the increased metabolic demands of the leg muscles are constrained due to the decreased blood flow. The result is claudication, defined as pain of the leg muscles during ambulation and is present in 40% of all PAD patients (Schainfeld, 2001). With rest, adequate blood flow eventually returns and the pain subsides. Claudication symptoms are treated with behavioral modifications, surgery and pharmacologically (Shainfeld, 2001). The two most prevalent pharmacological therapies use different approaches; the first (Treatment 1; T1) acts primarily by decreasing blood viscosity, while the second (Treatment 2; T2) acts primarily as a vasodilator (Dawson, 2001). Recently, research has examined PAD and the associated claudication as a primary gait disability (Gardner et al., 2001). However, this research has included only temporal and spatial parameters, such as stride length and step time, without exploring joint kinematics and kinetics. Similarly, studies investigating the effects of T1 and T2 also used the same limited approaches (Dawson et al., 2000). Thus, Gardner et al. (2001) suggested that these previous evaluations have been incomplete in their ability to describe the true gait handicap of PAD. Our goal was to further understand PAD gait and the influence of pharmacological therapies on the elimination of gait abnormalities. METHODS Nine PAD patients with diagnosed occlusion, which resulted in claudication, participated in the study. Five patients underwent T1 and four underwent T2. Because some patients were bilateral and some unilateral, we had nine total claudicating limbs affected by T1 and six total claudicating limbs affected by T2. Patients were asked to walk through a 10 meter walkway at self-selected normal walking pace, while ground reaction forces were collected by a Kistler force plate (600Hz). The patient performed five trials while pain free, or with no claudication (C1). The patient rested between each trial to ensure pain free data collection. Patients then walked on a treadmill at a 10% grade and at a speed of 0.67 m/s until the onset of pain. This protocol is common in PAD clinical examination. After pain was induced (C2), patients completed five more trials. Data collection was performed before (PRE) and after (POST) the use of each treatment. Treatment lasted a minimum of three months. Statistical analysis using 2x2 ANOVAs were performed on selected ground reaction force parameters. RESULTS AND DISCUSSION Regarding T1, the local minimum of vertical force experienced at midstance (Fzmin) was significantly decreased from PRE to POST. This indicates a higher positioning of the center of gravity and possibly a straighter leg at single support during the POST test. The braking impulse (IB) was significantly increased from PRE to POST indicating an