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Comparative Study
, 13 (10), e0205191

Lower Between-Limb Asymmetry During Running on Treadmill Compared to Overground in Subjects With Laterally Pronounced Knee Osteoarthritis

Comparative Study

Lower Between-Limb Asymmetry During Running on Treadmill Compared to Overground in Subjects With Laterally Pronounced Knee Osteoarthritis

Jacques Robadey et al. PLoS One.


Subjects with knee osteoarthritis (KOA) show gait asymmetries evidenced by lower knee flexion and shorter contact times for the affected leg. Interestingly, running on a treadmill compared to running overground is also associated with lower knee flexion and shorter contact times. Thus, it is of particular interest how gait patterns are influenced by the type of ground in subjects with KOA. The aim of the current study was therefore to measure the overground asymmetry of kinematic parameters in KOA subjects while running and to investigate whether this asymmetry is altered on a treadmill. Nine patients diagnosed with KOA underwent overground and treadmill running with 3D-motion analysis. The symmetry analysis was performed using Symmetry Angles for five selected gait parameters: contact and step time, heel-toe delay, maximal knee flexion during stance and vertical speed variance. For all parameters, the values were significantly lower for the affected compared to the non-affected leg (p≤0.023). Post-hoc analyses revealed significant differences between legs only overground and not on the treadmill. The asymmetry was lower on the treadmill, as indicated by significant Symmetry Angle reductions for contact time (p = 0.033), knee flexion (p = 0.001) and vertical speed variance (p = 0.002). The symmetry increase on the treadmill was mainly due to changes of the non-affected leg towards the affected leg values leading to smaller steps and less impact load in general. The present results suggest therefore that a) an assessment of symmetry may differ depending on the ground type (treadmill versus overground) and b) treadmill running may be more suitable for patients with KOA related gait asymmetries.

Conflict of interest statement

The authors have declared that no competing interests exist.


Fig 1
Fig 1. Running phases with maximal knee flexion and centre of pelvis vertical movement as a function of time.
The top panel is a schematic representation of a human running in sagittal plane with contact and flight phases. CP represents the centre of pelvis and α the maximal knee flexion during stance for the affected and the non-affected leg (AL, NL). The lower three panels show the CP height, vertical speed and vertical acceleration measured during an overground (OG) gait cycle for one KOA patient. The vertical speed variance corresponds to the difference between minimal and maximal vertical speed during stance (illustrated for both AL and NL). Note the larger vertical movement and speed variance for NL.
Fig 2
Fig 2. Kinematic parameters side dependency for OG and TM ground.
A) Overall results of the kinematic parameters for overgound (OG) and treadmill (TM) running. NL refers to the non-affected leg and AL to the affected leg. Boxplots show the results over all subjects. For each boxplot, the middle line represents the median value, the lower and upper limits represent the interquartile range and the error bars indicate the range and the plus signs denote outliers. Stars (*, **, ***) indicate significant differences (p<0.05, p<0.01, p<0.001) between NL and AL. Note that OG the differences between the NL and the AL were larger for all kinematic parameters compared to when running on the TM. B) Difference between the NL and AL value for all parameters. With dotted lines representing full symmetry, a symmetry increase is observed for all parameters.
Fig 3
Fig 3. Overall results of the Symmetry Angle for overground (OG) and treadmill (TM).
Boxplots show the results over all subjects with dotted lines corresponding to lines of full symmetry and stars indicating significant differences. We observe a Symmetry Angle decrease on TM compared to OG for all parameters, revealing a general symmetry increase on the TM.

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    1. Mills K, Hettinga BA, Pohl MB, Ferber R. Between-limb kinematic asymmetry during gait in unilateral and bilateral mild to moderate knee osteoarthritis. Arch Phys Med Rehabil. 2013;94(11):2241–7. 10.1016/j.apmr.2013.05.010 . - DOI - PubMed
    1. Creaby MW, Bennell KL, Hunt MA. Gait differs between unilateral and bilateral knee osteoarthritis. Arch Phys Med Rehabil. 2012;93(5):822–7. Epub 2012/03/06. 10.1016/j.apmr.2011.11.029 . - DOI - PubMed
    1. Gok H, Ergin S, Yavuzer G. Kinetic and kinematic characteristics of gait in patients with medial knee arthrosis. Acta Orthop Scand. 2002;73(6):647–52. 10.1080/000164702321039606 . - DOI - PubMed
    1. Wiik AV, Aqil A, Brevadt M, Jones G, Cobb J. Abnormal ground reaction forces lead to a general decline in gait speed in knee osteoarthritis patients. World J Orthop. 2017;8(4):322–8. 10.5312/wjo.v8.i4.322 . - DOI - PMC - PubMed
    1. McCarthy I, Hodgins D, Mor A, Elbaz A, Segal G. Analysis of knee flexion characteristics and how they alter with the onset of knee osteoarthritis: a case control study. BMC Musculoskelet Disord. 2013;14:169 10.1186/1471-2474-14-169 . - DOI - PMC - PubMed

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The authors received no specific funding for this work.