Paul Lundgren

Effect of an antipronation foot orthosis on ankle and subtalar kinematics.

INTRODUCTION/PURPOSE The aim of this study was to describe the effect of an antipronation foot orthosis on motion of the heel relative to the leg and explore the individual contributions of the ankle and subtalar joints to this effect. METHODS Five subjects were investigated using invasive intracortical pins to track the movement of the tibia, talus, and calcaneus during walking with and without a foot orthosis. RESULTS The antipronation foot orthosis produced small and unsystematic reductions in eversion and abduction of the heel relative to the leg at various times during stance. Changes in calcaneus-tibia motion were comparable with those described in the literature (1°-3°). Changes at both the ankle and subtalar joints contributed to this orthotic effect. However, the nature and scale of changes were highly variable between subjects. Peak angular position, range of motion, and angular velocity in frontal and transverse planes were affected to different degrees in different subjects. In some cases, changes occurred mainly at the ankle; in other cases, changes occurred mainly at the subtalar joint. CONCLUSION The changes in ankle and subtalar kinematics in response to the foot orthosis contradict existing orthotic paradigms that assume that changes occur only at the subtalar joint. The kinematic changes due to the orthosis are indicative of a strong interaction between the often common function of the ankle and subtalar joints.

The effect of a midfoot cut in the outer sole of a shoe on intrinsic foot kinematics during walking

Modifications in shoe outer soles are frequently made with the intention of altering biomechanics of the foot inside the shoe. These modifications are however, generally based upon intuition with little or no scientific data for support. The purpose of this study was to quantify changes in intrinsic foot segmental kinematics between walking in a neutral shoe and a shoe modified with a clear cut forming a break underneath the midfoot, approximating the Lisfrancs joint. Five healthy male subjects participated in the study. Intracortical pins were inserted under sterile conditions and local anaesthetic in nine different bones of the foot and shank. The subjects performed 10 walking trials in both a neutral, standard, flatsoled, flexible walking shoe and in the same shoe with an approximately 1 cm deep cut aligned with the subjects’ Lisfrancs joint. Material tests showed that the cut reduced midfoot shoe bending stiffness by 23% to 38% and torsional stiffness by 23% to 28%. A helical axis approach was applied for calculating the 3D rotations about relevant joints. Kinematic trajectories in the sagittal, frontal, and transverse planes were normalised to the stance phase for seven selected joints to compare rotation patterns when wearing the two shoe conditions. Although one out of 21 ranges of motion (ROM) showed a significant difference, there is strong reason to regard this as the result of a type 1 error. Apart from this no differences in ROM occurred between the shoe conditions. The low subject number reduced the statistical power of the results. However, the study indicated that outer sole modifications that may be assumed to have clear effects upon foot kinematics, do not necessarily do so.

Motion of the rearfoot, ankle and subtalar joints and ankle moments when wearing lateral wedge insoles – results from bone anchored markers

Background Knee osteoarthritis is a debilitating condition and increased dynamic loading at the knee has been linked with increased progression of the disease. Lateral wedge insoles have been used in clinical practice since the late 1980s. It is theorised that lateral wedge insoles increase the subtalar joint valgus orientation and increase the ankle valgus moment [1], with subsequent reduced knee varus moments [2]. Results have shown that both clinical success and reductions in knee loading vary between people. Differences could be due to person specific foot biomechanics. The aim of this study was to determine the changes in frontal plane foot and ankle motion and moment due to a lateral wedge orthosis.

Invasive study of rearfoot, midfoot and forefoot kinematics during walking

There is a dearth of quality information on the kinematics of the mid and forefoot during ambulation. We investigated the kinematics of the tibia, fibula, talus, calcaneus, cuboid, navicular, medial cuneiform, first and fifth metatarsals during walking using intra cortical pins. Kinematic and kinetic data was captured during ten walking trials at self selected pace. Data were processed in Qualysis software and Matlab and Euler rotations calculated.

Intrinsic foot motion measured in vivo during barefoot running

Knowledge of the natural range of motion of individual skeletal segments in the foot during running is necessary for the construction of appropriate stability parameters in athletic footwear. Globally restricting intrinsic motion of the foot may result in non-physiological stresses on specific foot bones or at more proximal sites such as the ankle ligaments. This study presents data on relative three-dimensional motion of individual foot segments, measured in vive with the use of reflective marker arrays attached to intracortical pins inserted in the tibia, talus, calcaneus, cuboid and navicular under local anaesthetic. Data were collected using a 10-camera optoelectric system (Qualysis, Sweden). Mean data for one subject (9 overground barefoot running trials, mean velocity: 2.2 m/s) are presented in table 1. The trials were reproducible (maximum 95% CI across all parameters: 2.3°).

Shoe and in-shoe manipulation effects on foot and ankle kinematics; advances through intracortical pin based methods

The analysis of what precise effects changes of shoe or in-shoe orthosis design have upon intrinsic foot or ankle kinematics has been hampered by two main problems preventing accurate description of the segments of interest. Firstly the shoe itself covers most of these structures and secondly many of the segments are small bones with no clear external landmarks for identification or marker attachment. There is a history of the application of intracortical pins for precise definition of bone segments in the lower leg and foot dating back to the early 1990s. Some of these studies (Reinschmidt et al. 1992, Stacoff et al. 1992) also analysed the movement of the foot within the shoe and ankle kinematics when wearing shoes. Recently a further group of studies of this research group has advanced this technique for also investigating smaller, intrinsic segments in the foot when shoe outer soles (Arndt et al. 2012) or in-soles (Liu et al. 2012) are used to alter kinematics.