Rasmus Gottschalk Nielsen

Determination of normal values for navicular drop during walking: a new model correcting for foot length and gender

BackgroundThe navicular drop test is a measure to evaluate the function of the medial longitudinal arch, which is important for examination of patients with overuse injuries. Conflicting results have been found with regard to differences in navicular drop between healthy and injured participants. Normal values have not yet been established as foot length, age, gender, and Body Mass Index (BMI) may influence the navicular drop. The purpose of the study was to investigate the influence of foot length, age, gender, and BMI on the navicular drop during walking.MethodsNavicular drop was measured with a novel technique (Video Sequence Analysis, VSA) using 2D video. Flat reflective markers were placed on the medial side of the calcaneus, the navicular tuberosity, and the head of the first metatarsal bone. The navicular drop was calculated as the perpendicular distance between the marker on the navicular tuberosity and the line between the markers on calcaneus and first metatarsal head. The distance between the floor and the line in standing position between the markers on calcaneus and first metatarsal were added afterwards.Results280 randomly selected participants without any foot problems were analysed during treadmill walking (144 men, 136 women). Foot length had a significant influence on the navicular drop in both men (p < 0.001) and women (p = 0.015), whereas no significant effect was found of age (p = 0.27) or BMI (p = 0.88). Per 10 mm increase in foot length, the navicular drop increased by 0.40 mm for males and 0.31 mm for females. Linear models were created to calculate the navicular drop relative to foot length.ConclusionThe study demonstrated that the dynamic navicular drop is influenced by foot length and gender. Lack of adjustment for these factors may explain, at least to some extent, the disagreement between previous studies on navicular drop. Future studies should account for differences in these parameters.

Video based analysis of dynamic midfoot function and its relationship with Foot Posture Index scores

INTRODUCTION Various studies have demonstrated significant as well as non-significant relationships between static evaluation of foot posture and injury likelihood. Therefore, the relationship of static and dynamic measures needs to be established as in clinical settings time consuming dynamic methods are often not feasible. PURPOSE Assess reliability of a new method to quantify midfoot movement and validate the use of Foot Posture Index (FPI) classification as predictor of dynamic foot function during walking. METHOD Foot type was classified using FPI in 280 randomly selected adult participants (mean age 43.4 years). A Video Sequence Analysis (VSA) system was used to quantify midfoot kinematics during walking. Navicula drop (DeltaNH) and minimal navicula height (NHL) were compared with FPI. RESULTS The Intraclass Correlation Coefficients (ICC) for DeltaNH and NHL ranged from 0.65 to 0.95 with a coefficient of repeatability of 1.4 mm for DeltaNH and 4.5 mm for NHL. System precision was estimated at 0.99 mm for DeltaNH and 3.18 mm for NHL. DeltaNH was significantly positively correlated with FPI scores while NHL decreased with increasing FPI. However, the FPI model predicted only 13.2% of the variation in DeltaNH and 45% of the variation in NHL during walking (p<0.001). CONCLUSION The VSA was proven as a reliable and precise method to quantify midfoot kinematics. FPI scores and individual components of the FPI show strong statistical relationships to dynamic measures but individual predictions remain questionable. Dynamic midfoot measures are recommended for clinical foot assessments.

Perspectives for clinical measures of dynamic foot function—Reference data and methodological considerations

Several studies have investigated if static posture assessments qualify to predict dynamic function of the foot showing diverse outcomes. However, it was suggested that dynamic measures may be better suited to predict foot-related overuse problems. The purpose of this study was to establish the reliability for dynamic measures of longitudinal arch angle (LAA) and navicular height (NH) and to examine to what extent static and dynamic measures thereof are related. Intra-rater reliability of LAA and NH measures was tested on a sample of 17 control subjects. Subsequently, 79 subjects were tested while walking on a treadmill. The ranges and minimum values for LAA and NH during ground contact were identified over 20 consecutive steps. A geometric error model was used to simulate effects of marker placement uncertainty and skin movement artifacts. Results demonstrated the highest reliability for the minimum NH (MinNH), followed by the minimum LAA (MinLAA), the dynamic range of navicular height (DeltaNH) and the range of LAA (DeltaLAA) while all measures were highly reliable. Marker location uncertainty and skin movement artifacts had the smallest effects on measures of NH. The use of an alignment device for marker placement was shown to reduce error ranges for NH measures. Therefore, DeltaNH and MinNH were recommended for functional dynamic foot characterization in the sagittal plane. There is potential for such measures to be a suitable predictor for overuse injuries while being obtainable in clinical settings. Future research needs to include such dynamic but simple foot assessments in large-scale clinical studies.

Navicula drop test ad modum Brody: does it show how the foot moves under dynamic conditions?

BACKGROUND Understanding foot motion and function during activity is essential for clinicians because different foot types may require different treatment or rehabilitation strategies. Brody introduced the static navicular drop (ND) test, which was meant as a quick clinical test to estimate foot pronation during dynamic conditions. However, how well static ND predicts dynamic ND during walking has never been investigated. The purpose of this study was to investigate how well static ND corresponds to dynamic measures of ND during treadmill walking. METHODS A custom video analysis system was used to assess dynamic ND during treadmill walking. The ND test ad modum Brody was used to evaluate static ND. RESULTS Static ND showed a significant correlation with dynamic ND (r = 0.357, r(2) = 0.127, P < .001). Navicular height at heel strike demonstrated a significant correlation with navicular height at the start position of static ND (r = 0.756, r(2) = 0.571 P < .001). Minimal navicular height during walking was significantly correlated with the end position of static ND (r = 0.951, r(2) = 0.904, P < .001). CONCLUSIONS This study of asymptomatic individuals did not confirm that static ND can be used to individually predict dynamic ND during treadmill walking. It was demonstrated that the start position of Brodys test is not well correlated with navicular height at heel strike, with this being the main reason for the weak relationship between static and dynamic ND measures.

The predictive value of the foot posture index on dynamic function

Keenan et al [1] identified the six-item version of the Foot Posture Index (FPI) as a valid, simple and clinically useful tool. The model combines measures of the standing foot posture in multiple planes and anatomical segments. It provides an alternative to existing static clinical measures when dynamic measures are not feasible. Redmond et al. [2] found the model able to predict 41% of the variation in the complex rotation of the ankle joint, representing inversion/eversion, during midstance of walking. To our knowledge no studies have been published on the relationship between the FPI and the movement of the midfoot during walking. The purpose of this study was to investigate the use of FPI classification as a predictor for dynamic midfoot kinematics during walking.