File
Blasimann A.1, Eichelberger P.1, Lutz N.1, Radlinger L.1, Baur H.1
1Bern University of Applied Sciences, Health, Bern, Switzerland
Background: Adult acquired flatfoot is a frequent problem with 19% prevalence and leads to hazardous complaints and walking dysfunction. It is generally believed that the dynamic foot function depends to a significant extent on the shape of the foot. While static alignment features (e.g. static navicular drop) are commonly assessed, their validity to describe dynamic foot function has not been established. To gain a most possible comprehensive view on physiological changes during functional activities (e.g. level walking, stair climbing), dynamic “mechanics” have to be measured with three-dimensional motion capture systems.
Purpose: The aims of this descriptive, cross-sectional laboratory study were to investigate the reliability of a new parameter, the dynamic navicular rise (dNR), and its relationship with the dynamic navicular drop (dND) during level walking and stair descent.
Methods: To assess the navicular bone motion during stance, 20 healthy participants (mean age 30.2 ± 8.1 years) had to walk on even ground and downstairs. A three-dimensional motion capturing system and force plates recorded data of ten trials per task on two measurement days. The dNR was extracted from the mean curves and defined as the difference between the minimum navicular height during stance and the navicular height at toe off. To test intra- and interday reliability, Bland-Altman plots were drawn, Intraclass Correlation Coefficients (ICC2.1) and repeatability were calculated. Furthermore, the relationship between the dNR and the dND was examined by calculating Pearson (r), Spearman (rs) correlations and regression coefficients (b), and visualization with scatterplots.
Results: Included participants showed a mean dNR of (12.2 ± 3.7) mm for level walking and (14.8 ± 3.4) mm for stair descent. The ICC2.1 for the dNR were 0.98 (intraday), 0.91 (interday) for level walking and 0.97 (intraday), 0.94 (interday) for stair descent. The repeatability for interday comparisons was 3.2 mm for level walking and 2.7 mm for stair descent. The correlation coefficients for comparison of the dNR with the dND were r= 0.31, b = 0.5 (p = 0.049) for level walking, and rs = 0.88, b = 1.08 (p 0.001) for stair descent.
Conclusion(s): Regarding ICCs, the dNR seems to be highly reliable. However, the repeatability is not acceptable. For level walking, the dNR may tend to be an independent measure for late stance dynamics. For stair decent, the dNR resembles the dND and therefore, gives no additional information. As only healthy subjects had been measured, the results cannot be transferred directly to patients. Future research should include larger sample sizes and/or focus on patients.
Implications: To better understand foot function under dynamic conditions, more research in the movement laboratory but also the transfer in a less sophisticated surrounding is needed to bring the results into daily practice.
Even though not every person with flatfoot gets symptoms, it is worth to know the underlying mechanisms as well as biomechanical consequences for posture and motion in order to support prevention for the known associations between flatfoot and foot pain, low back pain and for example medial tibial stress syndrome.
Funding acknowledgements: This work was funded by the Swiss National Science Foundation (Project number 140928).
Topic: Research methodology & knowledge translation
Ethics approval: Ethics approval was obtained from the ethics committee of the Canton Berne, Switzerland (KEK N0 Z007/12).
All authors, affiliations and abstracts have been published as submitted.
