Elsevier

Gait & Posture

Volume 25, Issue 1, January 2007, Pages 127-134
Gait & Posture

Effect of feet hyperpronation on pelvic alignment in a standing position

https://doi.org/10.1016/j.gaitpost.2006.02.005Get rights and content

Abstract

Hyperpronation may cause malalignment of the lower extremity, frequently leading to structural and functional deficits both in standing and walking. Our aim was to study the effect of induced foot hyperpronation on pelvic and lower limb alignment while standing. Thirty-five healthy subjects were requested to remain in a natural standing position for 20 s in four different modes: feet flat on the floor, and on wedges angled at 10°, 15° and 20°, designed to induce hyperpronation. Sequencing was random, repeated three times and captured by eight computerized cameras using the VICON® three-dimensional motion analysis system. We found that standing on the wedges at various angles, induced hyperpronation, with 41% to 90% of the changes attributable to the intervention. In addition, a statistically significant increase (paired t-test) in internal shank rotation (p < 0.0001), internal hip rotation (p < 0.0001) and anterior pelvic tilt (p < 0.0001) was identified. A strong correlation was found between segmental alignment in every two consecutive modes at all levels (r = 0.612–0.985; p < 0.0001). These findings suggest that alignment of the lower extremity up to the pelvic girdle, can be altered, due to forces acting on the foot. Interaction between the foot and pelvis occurs in a kinematic chain reaction manner. Although this study was limited to healthy subjects, clinicians should be aware that when addressing pelvis and lower back dysfunction, foot alignment should be examined as a contributing factor.

Introduction

The functional structure of the human foot is adapted for bipedal locomotion [1] as foot alignment plays a crucial role in standing and walking. The subtalar movement allows the foot to change from a flexible to rigid structure during normal gait, enabling the foot to adapt to uneven terrain and act as a rigid lever for force transition [2], [3], [4].

The subtalar axis produces six degrees of freedom movement capacity, eliciting three plane movements, supination and pronation [5], [6]. In a normal gait cycle, pronation occurs immediately after initial contact, permitting foot flexibility at loading response, shock absorption and adaptation of the foot to the weight-bearing surface [2]. Normal rearfoot pronation while walking has been found to fluctuate between single leg standing and subtalar neutral position [7], [8], [9], with maximum eversion of 6.3° (3.2°) [7] occurring at 37.9% of the stance phase [9]. The normal biomechanics of the foot might be disrupted, as a result of abnormal function of the subtalar joint, namely, excessive pronation or hyperpronation. Hyperpronation is defined as rearfoot pronation that is excessive, prolonged, and, as a result, causing the foot to remain in maximum pronation, to late or never resupinate in terminal stance for push off [2], [10], [11].

Measuring kinematics of the subtalar joint is difficult since foot segments and range of motion are comparatively small, with movement simultaneously occurring in three different planes. Recently, several biomechanical models were developed to measure foot motion; however, their suitability to be integrated into a full lower limb assessment is limited. A clinical method originally described by Root et al. [12] has been accepted in many studies [10], [13], [14], [15], [16], [17] as a measurement of the rearfoot coronal component, eversion and inversion (Fig. 1). Two lines bisecting the leg and the heel form the angle of the coronal component, representing pronation and supination.

The subtalar joint is the functional unit connecting the foot and shank. It has been postulated that subtalar movement and position influence the function of the foot and lower limb biomechanical alignment [11], [18]. Subtalar joint pronation is correlated with internal rotation of the shank, whereas supination is correlated with external rotation [13], [16], [19], [20]. Tiberio [11] maintained that excessive pronation of the foot during weight bearing causes internal rotational stress at the lower extremity, and may lead to increased strain on soft tissue and compression forces on the joints, which can become symptomatic. A review of the literature indicates that a relationship exists between hyperpronation of the foot and shank rotation, patella and knee joint alignment [11], [13], [16], [18], [20].

To the best of our knowledge, there is no documented evidence describing the relationship between hyperpronation and alignment of the pelvis and lumbar spine. However, several researchers suggest this possibility [2], [11], [14], [18], [21]. According to clinical observation hyperpronation is found to be highly prevalent. Thus, the purpose of this study was to examine the immediate effect of induced hyperpronation of the feet on the pelvis and lower limb alignment in the standing position.

Section snippets

Subjects

Thirty five healthy subjects (15 men, 20 women), aged 23–33 years, weight 50–91 kg, height 155–185 cm), physiotherapists from nearby clinics and physiotherapy students, volunteered to take part in the study. There was no history of musculoskeletal injuries. The study was approved by the institutional ethics (Helsinki) Committee, and all subjects signed an informed consent form.

The study was conducted at a gait and motion analysis laboratory. Each subject underwent a thorough musculoskeletal

Inducing hyperpronation by using wedges: change in the calcaneal alignment

The average change in eversion due to standing on the wedges is documented in Table 1. A significant increase in calcaneal eversion occurred (left: p < 0.0001, right: p < 0.052, with the exception of the change occurring on the transition to the second wedge p = 0.286), corresponding with the increase in the slope's angle, and reached a cumulative change in the calcaneal angle of 7.06° on the left, and 5.94° on the right. Fig. 3 demonstrates a slight drift towards the upper values with an increase of

Discussion

Our main finding was that pelvic alignment is influenced by foot alignment irrespective of plane of motion. In terms of biomechanics, the human body is a multi-segmental structure initiating major and powerful interactions between adjacent segments. Interaction between segments that are further apart may also hold a high significance for symptom free musculoskeletal function.

The pelvis, an important segment, situated in the center of the body, connects the upper body to the lower limbs. Due to

Conclusions

Our results support the existence of a kinematic chain in healthy subjects, where hyperpronation can lead to an immediate shank and thigh internal rotation and change in pelvic position. This interaction was evaluated while standing and should be examined in other tasks such as walking, running, climbing and descending stairs, where higher forces are applied, leading to larger kinematic changes. Furthermore, an asymmetrical change in foot alignment should be considered since it may cause

Acknowledgements

The authors wish to thank the Tel-Aviv Medical Center and Prof. Shlomo Wientroub, Head of the Department of Pediatric Orthopedics, for approving this study, conducted at the Dana Gait and Motion Analysis Laboratory; the Vicon support team for their contribution to writing the algorithm; Dana's Gait and Motion Analysis Laboratory staff; Meital Kfir and Reuven Batt for their help in data collection and processing; Mrs. Ana Bachar, Department of Anatomy, Tel-Aviv University, for preparing the

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