Evaluation of a single leg stance balance test in children Thomas Zumbrunn b , Bruce A. MacWilliams a,b,c, *, Barbara A. Johnson a a Shriners Hospitals for Children, Salt Lake City, UT, USA b Department of Bioengineering, University of Utah, Salt Lake City, UT, USA c Department of Orthopaedic Surgery, University of Utah, Salt Lake City, UT, USA 1. Introduction Postural stability or balance is the ability to maintain the body in equilibrium by keeping the projected center of mass (COM) within the limits of the base of support [1]. According to Gage, stability in stance is the first prerequisite for normal gait [2]. There is a repeated and rhythmic alternation of double and single leg support during walking with periods of single support necessary to allow swing phase mechanics of the opposite limb; hence the ability to control the COM during single leg stance is important for independent walking [3]. Humans use multiple sensory systems to maintain an upright posture including the vestibular system, the visual system and the somatosensory system. Most previous work has focused on children with neuro-motor impairments and used double leg stance for balance testing [4–6,3]. These protocols usually include eyes open and eyes closed test-variations. For subjects without neurological conditions, these protocols may not test the ability of the musculoskeletal system to provide functional balance in single limb support during gait. Additionally high functioning individuals without vestibular or visual impairments may not be sufficiently challenged using double support tests. In this case double limb support protocols may fail to detect longitudinal changes or differences compared to controls. There are few reports of single limb balance investigations. The Romberg Test is a timed single leg stance protocol, but has not been used with force plate data [7–9]. Reports of single limb balance using force plate measures have been limited to investigations of ankle instability in adults [10–14] and an analysis of balance differences between genders in nine to eleven year old children [15]. Congenital talipes equinovarus (CEV), also referred to as clubfoot, is one of the most common musculoskeletal birth defects [16]. It occurs in one of 1000 live births and is considered idiopathic since it occurs mostly as an isolated birth defect [17]. CEV consists of bony deformities, soft tissue contractures and muscular weakness. The foot is positioned in supination, adduction and varus when standing. Compared to normal feet, the smaller support area, muscular disbalance and joint instability may impair balance in patients with CEV [16,18]. The first aim of this study was to describe a single leg balance test on a force plate to quantify typically developing children’s ability to maintain single limb support. Developmental motor tests for children have documented increased ability to balance in single limb support with maturation [19]. We hypothesized that the Gait & Posture xxx (2011) xxx–xxx ARTICLE INFO Article history: Received 23 March 2010 Received in revised form 24 March 2011 Accepted 5 April 2011 Keywords: Balance Center of pressure Force plate Children Equinovarus Club foot ABSTRACT Balance is a major determinate of gait. In high functioning individuals without significant vestibular or vision impairments, a ceiling effect may be present when using a double limb support protocol to assess balance function. For these populations, a single leg stance protocol may be more suitable. 47 typically developing (TD) subjects and 10 patients with CEV performed a single leg stance test on a force plate. The center of pressure (COP) was determined and several COP derived variables were calculated. Included measurements were: standard deviation, maximum excursion, area, average radial displacement, path velocity and frequency of the COP. Directional components of suitable variables were used to analyze anterior/posterior and medial/lateral contributions. Correlations with age of TD subjects indicated that all balance variables except frequency were significantly correlated. Most parameters were highly inter- correlated. Age adjusted COP balance variables also correlated to the Bruininks-Oseretsky balance subtest. Highest correlations were determined by the maximum excursion and velocity of the COP in the anterior/posterior direction. Statistical comparisons between the CEV group and a 4–6 TD group indicated significant differences between groups for most COP balance parameters. These results indicated that a single limb balance assessment may be a useful assessment for determining balance impairments in higher functioning children with orthopedic impairments. ß 2011 Elsevier B.V. All rights reserved. * Corresponding author at: Motion Analysis Laboratory, Shriners Hospitals for Children-Salt Lake City, Fairfax Rd. @ Virginia St., Salt Lake City, UT 84103, USA. Tel.: +1 801 536 3800; fax: +1 801 536 3782. E-mail address: bmacwilliams@shrinenet.org (B.A. MacWilliams). G Model GAIPOS-3267; No. of Pages 4 Please cite this article in press as: Zumbrunn T, et al. Evaluation of a single leg stance balance test in children. Gait Posture (2011), doi:10.1016/j.gaitpost.2011.04.005 Contents lists available at ScienceDirect Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost 0966-6362/$ – see front matter ß 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.gaitpost.2011.04.005