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Session: Poster session I
Session starts: Thursday 24 January, 15:00

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Jim Schrijvers ()
Derek Rutherford ()
Rosie Richards ()
Josien van den Noort ()
Martin van der Esch ()
Jaap Harlaar ()

Abstract:
Purpose: Gait analysis is regularly used to test efficacy of interventions and to better understand knee function in individuals with knee osteoarthritis (OA). Assessment of gait is performed in many laboratories across the world utilizing custom setups and protocols. This creates the potential for large inter-lab variance when comparing results. Dalhousie University (DAL, Canada) and VU medical center (VUmc, the Netherlands) are striving to establish a collaborative initiative to combine resources in future gait studies in individuals with knee OA. Therefore, the aim was to evaluate the inter-laboratory comparison of previous collected knee gait waveforms of individuals with knee OA. Methods: Knee gait waveforms (three-dimensional (3D) angles, 3D moments and muscle activations) were analyzed of the affected leg of individuals with moderate KOA previously collected with a R-mill instrumented treadmill, a motion capture system and electromyography at DAL (n=55) and VUmc (n=40). Inter-laboratory comparison was performed using analysis of variance models of the population characteristics, common discrete values of the waveforms (peak, initial contact (IC) and impulse values) and principal pattern (PP) scores (resulted from principal component analysis (PCA)). Results: The DAL population was shorter (0.04m; p=0.02), heavier (5.9kg; p=0.04), had higher knee flexion strength (20Nm, p<0.01) and lower pain scores (WOMAC1 Pain: 6; p<0.01). PCA identified an amplitude offset in the sagittal and frontal plane angles (PP1-scores: p<0.01; 11.8˚ and 4.1˚, respectively), as well as in the sagittal plane moments (PP1-scores: p<0.01, 0.16 Nm/kg). The frontal plane moments were identical, as shown by similar PP-scores and discrete values. The gait waveforms of the quadriceps, hamstrings and gastrocnemius had a phase shift between laboratories (PP2 or PP3-scores: p<0.01; 4%, 4% & 6% of gait cycle, respectively). Conclusion: This inter-laboratory comparison of treadmill gait in individuals with knee OA revealed systematic offsets (amplitude and phase) that obstruct the merging of gait datasets from laboraties. Marker models, collection and processing decisions (i.e. filters and IC identification) may explain these results. There is a need for a standardized, harmonized gait analysis protocol to enable combined databases and multi-center trials for knee OA gait analyses.