Sjúkraþjálfarinn 27 Briem, Kristin 1 ; Axe, Michael J. 2,1 Snyder- Mackler, Lynn 1 ; 1. Biomechanics and Movement Science, Uni- versity of Delaware, Newark, DE, USA. 2. First State Orthopaedics, Newark, DE, USA. ABSTRACT: Introduction: Knee OA is a common cause of decline in function and is gener- ally associated with joint malalignment and laxity, joint space narrowing, qu- adriceps weakness, as well as sclerosis and attrition of subchondral bone. Intra- articular (IA) injections of Hyaluronic Acid (HA) are indicated to palliate symptoms and improve function in pati- ents with knee OA. Primary outcome measures in studies on the efficacy of this treatment are largely self reports of pain and function. The purpose of the study was to investigate the effects of HA injections on knee function and sagittal plane kinematics in patients with knee OA. Materials and Methods: Thirteen subjects with symptomatic knee OA and scheduled for 5, weekly, IA injections of HA were recruited. Each subject was tested for baseline data. Post- treatment testing sessions were conduct- ed within 3 weeks of finishing the series of HA and again five months after treat- ment. Kinematic data were collected at 120 Hz using an eight camera motion analysis system (VICON, Oxford Metrics). Subjects walked along a 10 m walkway at self-selected pace. Ten walking trials were collected and avera- ged. Knee function was assessed with a knee specific questionnaire (Knee Outcome Survey (KOS)), goniometric range of motion (ROM) measures, a six minute walk (6MW) and a timed stair climbing task. Quadriceps strength was evaluated isometrically at 90° with a KinCom dynamometer (Chattanooga Group, Inc., Chattanooga, TN) and ex- pressed as a ratio of the force output of the involved vs. uninvolved side (Qu- adriceps Index (QI)). Repeated measures analysis of variance (ANOVA) with pairwise comparisons, multivariate analysis, linear regression analysis and paired t-tests were used to analyze the data. Alpha was set at 0.05. Results: Multivariate analysis of knee flexion angles was used at two stages of weight acceptance; initial contact (IC) and peak knee flexion (PKF) between in- volved (INV) and uninvolved (UNINV) knees across the three testing times. The analysis showed an interaction between stage of weight acceptance and side (F=18.716; p=0.001). There were signi- ficant interlimb differences in knee exc- ursion during weight acceptance (flexion angle from IC to PKF) for the first (5.3°; p=0.005), second (5.2°; p=0.001) and third (5.2°; p=0.001) testing times; the affected knee demonstrating less movement. Excursions of the INV and the UNINV knees did not change across testing times. Multivariate analysis of goniometric total knee ROM between the INV and UNINV knee across testing times showed an interaction by side (F=29.996; p<0.001) but not for testing time. The INV knee’s ROM was on average 8° less than that of the UNINV at the first testing session (p=0.003), 5.2° less at the second (p<0.001) and 7.2° less at the third testing session (p=0.001). Knee ROM of either knee did not change across testing times. Larger knee flexion ROM at baseline predicted greater improvement on KOS scores on the first post-treatment testing session (r2=.540; p=0.004). Larger knee flexion ROM at the first post-treatment predicted greater improvements on KOS scores at the later testing session (r2=.398; p=0.021). Significant within-subjects effects of testing times on KOS scores were found(F=4.65; p=0.02),on 6MW distance (F=12.010; p<0.001) and QI (F=5.903; p=0.013). Discussion: Subjects demon- strated significantly improved function after a series of intra-articular hyaluronan injections as evaluated with the KOS and functional testing. Kinematic interlimb differences were unchanged across test- ing times despite these improvements. Ganga, fær ni og styr kur eftir hyalur onan spr autumeðfer ð vegna einkenna fr á slitgigt í hné Gait, function and quadr iceps str ength after intr aar ticular hyalur onan injections in patients with symptomatic knee osteoar thr itis K RISTÍN B RIEM