Background
A variety of multi-segmental foot models have been produced to examine patterns of foot segmental movement during gait cycle to identify biomechanical differences between normal and pathological foot function[1‐3]. The reliability of foot models to accurately describe motion of the foot joints is dependent on the ability of the examiner to repeatedly apply markers to specific landmarks and the relevance of models’ segmental descriptions to underlying anatomy. The aim of this study was to test the reliability of segmental angles measured by three published foot models during paediatric gait.
Materials and methods
Sixteen children, aged 6 to 12 years old, were recruited to the study. Marker sets for three foot models 3DFoot[1], Oxford Foot Model (OFM)[2], and Kinfoot[3] were applied to their right feet simultaneously which to the authors knowledge, is the first direct comparison of the three models during gait. Each foot model was assessed for repeatability of maximal joint angle and range of motion during the gait cycle between two testing occasions. Absolute angular differences and standard error of measurement (SEM) are reported.
Results
Repeatability of all maximal segmental angles and range of motions were higher in 3DFoot compared to OFM and Kinfoot (Table 1).
Table 1
Inter-session repeatability of foot model’s 3D maximal segmental angles over the gait cycle.
Model | Segments | Maximal joint angle | Range of joint angle | ||
|---|---|---|---|---|---|
° Difference | SEM ° | ° Difference | SEM ° | ||
OFM | Hindfoot to Shank | 2.1 ± 15.1 | 10.9 | 1.2 ± 8.0 | 5.7 |
3DFoot | Hindfoot to Shank | 1.0 ± 5.2 | 3.6 | 1.0 ± 4.6 | 3.3 |
Kinfoot | Hindfoot to Shank | 1.0 ± 5.1 | 3.6 | 1.4 ± 6.3 | 4.3 |
3DFoot | Midfoot to Hindfoot | 0.8 ± 3.5 | 2.2 | 0.3 ± 2.7 | 1.9 |
Kinfoot | Midfoot to Hindfoot | 3.0 ± 11.1 | 6.7 | 3.7 ± 11.3 | 6.6 |
OFM | Metatarsals to Hindfoot | 0.8 ± 8.5 | 5.3 | 1.3 ± 5.7 | 5.4 |
3DFoot | Metatarsals to Midfoot | 0.7 ± 4.0 | 2.9 | 0.6 ± 3.6 | 2.5 |
Kinfoot | Metatarsals to Midfoot | 2.8 ± 7.8 | 4.8 | 2.6 ± 6.6 | 3.7 |
OFM | Hallux to Metatarsals | 2.3 ± 15.6 | 11.2 | 0.4 ± 13.7 | 9.1 |
3DFoot | Hallux to Metatarsals | 1.5 ± 10.0 | 6.2 | 0.4 ± 12.6 | 8.8 |
Kinfoot | Hallux to Metatarsals | 4.4 ± 21.8 | 15.1 | 2.1 ± 11.8 | 7.2 |
Conclusion
Decreased measurement error observed in 3DFoot and Kinfoot models may be attributable to normalisation of kinematics data to subject standing position. In the OFM, non-normalisation of gait data resulted in variable segmental offsets, particularly in the frontal plane. Greater measurement error was observed for several foot segments in the Kinfoot model. This may be due to discrepancies in model segment definitions in relation to the underlying joint anatomy, especially around the midfoot to hindfoot segments. 3Dfoot model consistently showed the least measurement error in the segment motions examined and thus is appropriate for use to examine foot biomechanics in gait.
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