The purpose of this study was to compare the kinematics of children with CP and individuals with chronic stroke during overground walking measured with marker-based and markerless motion capture systems using Theia3D. Few significant differences were observed between the two systems, suggesting this markerless technology could be a viable alternative for use in clinical settings. When possible, we discuss our comparisons in the context of Minimal Clinically Important Difference (MCID) and Minimal Detectable Change (MDC). Values at or below MCID or MDC suggest that any difference between the two systems is not great enough to affect clinical decision-making.
Root mean square values of joint angle variables had only two significantly different outcomes between marker and markerless systems (Table 2). Differences between the mean maximum joint angle measured by marker-based and markerless systems were minimal and below 4.5º (Appendix D). Differences between the mean minimum joint angle were also minimal and below 5º (Appendix E). Waveform comparisons from CMC and Pearson correlations had general trends of higher correlations in the sagittal plane joint angles than frontal and transverse (Appendix F).
At the trunk, mean differences of maximum and minimum joint angles between were less than 1º and not statistically significant amongst all planes. Discrete RMSE were between 2–4º for all planes, which resulted in large normalized RMSEs, particularly in the sagittal and frontal planes (Table 2). The total range of motion was also similar between the two systems with no statistical differences reported in our clinical populations.
At the hip, no significant differences were observed between systems in any anatomical plane for maximum joint angle of either limb or the minimum joint angle for the more affected limb. Mean differences in the sagittal plane (flexion/extension) were below an MDC of 4.69º and 4.01º shown for hip flexion and extension in stroke during stance and swing, respectively.(20) Transverse plane (rotation) of the more affected limb had a significant difference of 3.5º (Cohen’s d = 1.26, p = 0.017) for the minimum joint angle. The RMS for frontal plane motion of the hip was different between the two systems − 1.2º (Cohen’s d = 1.42, p = 0.026). However, RMSE for the more affected side was within 2.72º, and RMSE for the less affected side was smaller than that of 2.6º in healthy adults,(16) indicating that these results in neurological populations are near or within typical bounds of those in healthy adults.
There were no significant differences between the two systems at the knee, on either the more or less affected leg, in any of the three planes. The mean difference in minimum and maximum joint angles were less than the MCID for both knee sagittal plane range of motion of 8.48º for the affected side and 6.81º for the unaffected side(21) as well as the 6.43º and 5.25º MDC of knee flexion and extension during stance and swing in chronic stroke gait, respectively.(20) The frontal plane knee angle showed insignificant difference, consistent with previous literature,(16) again demonstrating that the difference between the two systems in neurological populations is similar to that in healthy adults.
At the ankle, the mean difference in the sagittal plane for both the more affected and less affected limbs was well within MDC of 2.05º and 3.95º shown for ankle dorsi- and plantarflexion in stroke in stance and swing for chronic stroke gait, respectively.(20) The RMS in the frontal plane for the less affected limb was significant (-1.3º [Cohen’s d = 1.04] p = 0.043). However, the RMSEs for the sagittal, frontal, and transverse planes were all less than those of healthy adults found in previous work (6.7º, 8.0º, and 11.6º, respectively(16)). This indicates our results in neurological populations are within the bounds of those of healthy adults.
This subject was a Gross Motor Function Classification System (GMFCS) level 1, which implies minor issues with ambulation. Waveforms are normalized to 100% of a gait cycle defined as initial contact to initial contact. Shaded regions represent one standard deviation about the solid line which represent ensemble means.
This subject was 6.55 years post-stroke and used a right ankle foot orthosis and two-wheel walker. Waveforms are normalized to 100% of a gait cycle defined as initial contact to initial contact. Shaded regions represent one standard deviation about the solid line which represent ensemble means.