Elsevier

Gait & Posture

Volume 67, January 2019, Pages 71-76
Gait & Posture

Dynamic evaluation of simulated leg length inequalities and their effects on the musculoskeletal apparatus

https://doi.org/10.1016/j.gaitpost.2018.09.022Get rights and content

Highlights

  • Leg length inequalities (LLI) can lead to significant musculoskeletal disorders.

  • Surface Topography measures the effects of LLI under static & dynamic conditions.

  • LLI lead to significant changes in spinal posture and pelvic position.

  • Magnitude of the effects of LLI were smaller under dynamic conditions.

  • With this method the effects of LLI can be evaluated under static & dynamic conditions.

Abstract

Background

Leg length inequalities (LLI) are a common problem in medicine. So far, the diagnosis and treatment are performed under static conditions. Surface Topography (ST) is an optical, non-invasive technique that uses the principle of triangulation to measure spinal posture and pelvic position. This technique offers the opportunity to detect and treat LLIs and their effects under dynamic conditions.

Research

question The aim of the study is to show that ST can detect simulated LLIs under dynamic conditions and to prove if there are differences between the effects on the human body under static and dynamic conditions.

Methods

In the clinical study a total of 30 test subjects were examined with a ST measuring device. LLIs (1 to 4 cm) were simulated using a custom- built sandal and insoles of various thickness. The pelvic obliquity, the surface rotation and lateral deviation of the spine were detected on a treadmill under static and dynamic conditions (3 km/h).

Results

Under static and dynamic conditions LLIs lead to a significant increase of all measured parameters. The pelvic obliquity reaches a significant level of p < 0.0001 under static and p = 0.0001–0.0421 under dynamic conditions. However, for all examined parameters the magnitudes of the parameters under dynamic conditions were smaller than under static conditions.

Significance

The study showed that simulated LLIs also have a significant effect on the human pelvis and spine under dynamic conditions, but with a smaller magnitude than under static conditions. The human individuum is a dynamic one. Because of that, for the future it should be of great interest to use dynamic measurements to detect and treat LLIs to provide an over correction of LLIs.

Introduction

Leg length inequality (LLI) is a condition in which paired limbs are noticeably unequal [1]. They can be found in 40–70% of the population and they may be greater than 2 cm in about 0.1% [1]. LLIs can be a predisposing factor for sacroiliac joint disorders, lumbar back pain, functional scoliosis as well as for symptoms in various joints due to the kinematic joint chain [2]. LLIs can affect all age groups and are categorized into anatomical and functional LLIs [1].

So far, the clinical diagnosis and treatment of LLIs is still performed mostly under static conditions, while patients are standing upright in front of the examiner. The amount of LLI is measured by palpating the height of the iliac crests and their position to each other. Larger LLIs lead to pelvic obliquity, which is then corrected by placing small blocks under the short leg until the pelvis is levelled. In multiple studies, the static effects of LLIs on the musculoskeletal system have been evaluated [[3], [4], [5]]. Hackenberg et al. [5] showed that there is a direct effect of simulated LLIs on the pelvic position and spinal posture [5]. Betsch et al. established a non-invasive method to simulate and examine LLIs and their effects on the musculoskeletal apparatus using a simulation platform [3,4]. The results of these studies confirmed a correlation between increasing LLIs and pelvic obliquity, torsion and changes of the spinal posture [3,4].

The human being is a dynamic individual [6] and therefore, we believe that the diagnosis and treatment of LLIs should also be carried out under dynamic conditions. With the development of surface topography there is a fast, reliable and radiation-free method available to diagnose and treat LLIs under dynamic conditions. In previous studies, the reliability and validity of this system under static and dynamic conditions was shown [[7], [8], [9], [10]].

Aim of this study was to develop a method for simulating and evaluating LLIs and their effects on the pelvis and spine under dynamic conditions.

Section snippets

Materials and methods

30 test subjects without pre-existing leg or spinal abnormalities were included in this study. Exclusion criteria of this first pilot study were a pelvic obliquity due to a functional or anatomical leg length discrepancy greater 10 mm and obesity with a body mass index (BMI) of greater 35 kg/m2, which could impede the detection of anatomical landmarks by the measuring system. Another exclusion criterion was back pain during the previous year lasting longer than 2 days. Mean age of the subjects

Static measurements (all results are presented in relation to the reference condition LLI = 0 mm)

Under static conditions a simulated LLI of 1 cm and greater led to a significant increase of the pelvic obliquity (p < 0.001) (Fig. 2).

The results also showed that with simulated LLIs of 1 cm and greater on the left and 2 cm and greater on the right side significant changes of the surface rotation occurred (left sided LLI: p = 0.0001–0.0229, right sided LLI: p = 0.0002–0.00016) (Fig. 3).

We also did find a significant increase under static conditions for the lateral deviation of the spine with

Discussion

Main goal of this study was to develop a method that allows the evaluation of LLIs under dynamic conditions. In order to be able to simulate and correct LLIs, we built three sets of sandals with insoles of varoius thickness (1–4 cm) that can accommodate most feet. We chose to use this model, instead of using regular shoe insoles with varying thickness, because we wanted to be able to simulate LLIs independent of the subjects anatomy, body weight and type of shoe wear.

The results of this study

Conclusion

LLIs can lead to multiple musculoskeletal disorders. The treatment and diagnosis of LLIs is still carried out under static conditions, although patients are moving and walking most of the time. We were able to develop and evaluate a novel method to simulate and examine the effects of LLIs on the musculoskeletal apparatus under dynamic conditions.

Conflict of interest

None

Declaration of interest

None.

Acknowledgments

All procedures performed in studies involving human participants were in accordance with the ethical standards of institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants included in the study. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for profit sectors.

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