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Nov 26, 2016 - Journal of Biomimetics, Biomaterials and Biomedical Engineering. Submitted: 2016-11-26 ... 2017 Trans Tech Publications, Switzerland.
Journal of Biomimetics, Biomaterials and Biomedical Engineering ISSN: 2296-9845, Vol. 30, pp 31-37 doi:10.4028/www.scientific.net/JBBBE.30.31 © 2017 Trans Tech Publications, Switzerland

Submitted: 2016-11-26 Revised: 2016-12-13 Accepted: 2016-12-14 Online: 2017-01-25

Dynamic Balance Analysis under Different Lower Extremities Tortuosity Dandan Qian1, Yuntao Li1*, Yang Shu1, Yaodong Gu1, Yan Zhang2, Jan Awrejcewicz2, Xuewen Jia3 1 2

Faculty of Sport Science, Ningbo University, Ningbo, China

Department of Automation, Biomechanics and Mechatronics, The Lodz University of Technology, Poland 3

Department of Orthopaedics, Ningbo First Hospital, China,

*Corresponding author: No.818 Fenghua Road, Ningbo, China 315211 Email: [email protected] Keywords: Y-Balance Test; incline; tortuosity; biomechanics.

Abstract. The purpose of this study was to explore the balance of different condition of grounds through changing the inclines, and investigate the influence of lower extremities in different inclines. Twenty healthy young males were taken as experimental participants. The Six-degree-of-freedom Motion Platform was taken to change the inclines to: -5°, 0°, 5°, 10°. The Vicon three-dimension motion analysis system was utilized to capture the spatiotemporal parameters and the three-dimensional coordinates of lower extremities. On uphill, incline had no significant impact on balance. But tortuosity of hip and knee could significantly increase with the incline. On downhill, balance was significantly less than flat. Tortuosity of knee joint was significant larger than it on the flat ground. The mobility of hip and knee joint was large on uphill; the mobility of knee is large on downhill, but the balance was reduced. These could provide useful biomechanics information on clinical evaluation with dynamic balance. The result might have great significance to the lower extremities rehabilitation. Introduction The star excursion balance test (SEBT) is a common measurement method of dynamic balance testing [1,2]. It is used to diagnoses the lower limbs functional defect by comparison of participants’ test results to healthy population test results [3]. This measurement method could evaluate chronic ankle instability (CAI) [4], analysis the anterior cruciate ligament(ACL) injury [5]. The Y-balance test (YBT) has built on previous research suggesting redundancy in the 8 directions of the SEBT to develop a more time-efficient test that evaluates dynamic limits of stability and asymmetrical balance in only three directions (anterior, posteromedial, and posterolateral) [1,2]. Initial evidence on the YBT for injury prediction is encouraging [6]. Incline is a common variable which could change the physical balance. The current research, for the most part, focuses on the walking or running with different inclines [7,8] and kinematics analysis of lower limbs on an inclined way [9,10]. There were no researches investigated biomechanics of lower limbs on different inclined surfaces. ‘Tortuosity’ is used to diagnose and evaluate a variety of diseases in biomedical research and clinical field[11,12]. It originally used to survey tortuosity of blood vessels. Eltoukhy et al. [13] investigated the differences in segmental tortuosity between SEBT reach directions. They found that tortuosity is a novel biomechanical measurement technique that provides an assessment of segmental movement during common dynamic tasks such as the SEBT. This enhanced level of detail compared to more global measures of joint kinematic may provide insight into compensatory movement strategies adopted following lower extremity joint injury.

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Journal of Biomimetics, Biomaterials and Biomedical Engineering Vol. 30

This study investigated the correlation between physical balance and inclines. It hypothesized the change of incline would influence the biomechanics of lower limbs. It was an innovation to apply the tortuosity as a new measurement technique to the lower limbs judgment, even the biomechanical study. Methods Participants Twenty healthy males volunteered to take part in the test. All the participants were university students. Participants were free from pain, injury or large surgery in lower limbs or lower back in the past six months and they were informed of the experimental procedure and objective with written consent. And this study was approved by the Ethic Committee of Ningbo University. Participants completed patient reported outcome measures including the Lower Extremity Functional Scale (LEFS) [14], Tegner Activity Level Scale [15], as well as a Visual Analog Scale (VAS) for current lower extremity pain. The results are provided in Table 1. Table 1 Participant demographics Total Participants 20 Age(years) 24.0±1.0 Height (cm) 174.3±2.3 Weight (kg) 68.1±4.4 Right leg length (cm)* 89.3±3.6 Body mass index 20.48±2.8 LEFS score 78.5±2.1 Tegner activity score 6.0±1.0 VAS 0.0±0.0 Note: Right leg length, measurement from right anterior superior iliac spine to medial malleolus. Experiment protocol The tests were performed in the Sports Biomechanics Laboratory of Ningbo University. A Vicon motion analysis system with 8-camera (Oxford Metrics Ltd., Oxford, UK) was used to capture the three-dimensional kinematics at the frequency of 200 Hz. The six-degree motion platform (MTD6.0, TARCH, CHINA) is capable of moving in three linear directions and three angular directions singly or in any combination. The control software connected with it during testing and it set the angle of inclines. Procedures The experiment of YBT was in Fig. 1. Participants drilled 4 times before the formal experiments started. The YBT was performed with the participant standing barefoot at the center on the Six-degree-of-freedom Motion Platform with 3 lines extending at 120° increments from the center. While maintaining single leg stance on the left leg, the participant reached with the free limb (right leg) in the anterior, posteromedial, and posterolateral directions as far as possible. The distance reached was normalized by the participant’s leg length. Six-degree motion platform was taken to change the inclines to: -5°, 0°, 5°, 10° (Fig. 2). Each participant tested three times in each incline randomly to achieve good consistency and stability of gait reducing experimental error. And it provided the direction was corresponding to the incline.

Journal of Biomimetics, Biomaterials and Biomedical Engineering Vol. 30

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Fig. 1 Reaching directions for the YBT

Fig. 2 Anterior reach of YBT in different inclines(Inclines: A:-5°, B:0°, C:5°, D:10°) Tortuosity calculation Bullitt [16] provided a new tortuosity metric with 3D images by the separate representation of vessel tortuosity: Sum of Angles Metric (SOAM):

 n −3

  n −1



 k =1

  k =1



SOAM =  ∑ CP K   ∑ PK − P K − 1  Vicon motion analysis system would collect the 3D coordinates of 6 Marker points during the YBT: right anterior superior iliac spine (RASI), right posterior superior iliac spine (RPSI), right lateral knee(RKNE), right lateral malleolus(RANK), right calcaneus (RHEE) and right second metatarsal head (RTOE). Results are given in deg/mm. Statistical analysis Statistical analysis was performed with STATA 12.0 software. One-way analysis of variance (ANOVA) with post-hoc Bonferroni correction was performed to investigate the differences between the main variables of interest. Statistical results were considered significant if p