Gait and Posture 20 (2004) 14–19 Impact of changing foot progression angle on foot pressure measurement in children with neuromuscular diseases  Wei-Ning Chang a , Athanasios I. Tsirikos b , Freeman Miller c,∗ , Jill Schuyler c , Joe Glutting d a Department of Orthopaedics, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan, ROC b Department of Orthopaedics, University of Athens, KAT Hospital, Athens, Greece c Department of Orthopaedic Surgery and Gait Analysis Laboratory, Nemours Children’s Clinic, Alfred I. duPont Hospital for Children, 1600 Rockland Road, P.O. Box 269, Wilmington, DE 19899, USA d University of Delaware, Newark, DE, USA Received 8 October 2002; received in revised form 5 April 2003; accepted 25 May 2003 Abstract To analyze the effect of lower-limb rotation on foot pressure distribution, 16 patients (23 feet) with neuromuscular diseases who received derotation osteotomy of lower limbs without concomitant foot–ankle procedures were included in this retrospective study. The cross-correlation analysis showed that the interval change of the foot progression angle was correlated with the interval change of the medial–lateral foot pressure impulse distribution. The externally rotated foot progression angle tends to introduce higher loading on the medial foot, and the internally rotated foot progression angle shifts the loading to lateral side of the foot. This study provides evidence that the rotational profile of the lower limb has a substantial impact on foot pressure distribution. © 2003 Elsevier B.V. All rights reserved. Keywords: Derotation osteotomy; Foot pressure; Foot progression angle; Pedobarograph 1. Introduction The foot progression angle (FPA) impacts the inversion and eversion moment of the foot. The FPA in stance phase is correlated with peak ankle inversion–eversion moment during late stance. The peak in external eversion moment at the ankle increases in subjects with greater degrees of an out-toeing gait [1,2]. Theoretically, the foot pressure measurement should be able to demonstrate higher me- dial pressure impulse if the subject has a more out-toeing gait. Other factors that affect the foot pressure measurement are the walking cadence [3], the number of trials [4], and the use of different systems [5,6]. However, the reports of the effect of limb rotation on foot pressure measurement (pe- dobarograph) have been infrequent [7,8]. In children with  Study conducted at the Alfred I. duPont Hospital for Children, Wilmington, Delaware, USA. ∗ Corresponding author. Tel.: +1-302-651-5921; fax: +1-302-651-5951. E-mail address: fmiller@nemours.org (F. Miller). cerebral palsy (CP), there are significant long-term seque- lae of lower extremity rotational disorders if left untreated. Children with CP have less potential to remodel, and the foot joints are more susceptible to external deforming forces [9]. The purpose of this study was to review the pedobarographs of neurologically involved patients who received derotation osteotomy (DRO) of lower limbs without concomitant ankle or foot procedures to determine the effect of changing the FPA on pedobarograph measurements. Since the out-toeing gait is associated with increased external ankle eversion mo- ment [1,2], our hypothesis was that the foot with a higher out-toeing progression angle should have a higher percent- age of pressure impulse (pressure–time integral) on the me- dial aspect of the foot. Likewise, the foot with a higher in-toeing progression angle should have a higher lateral im- pulse on foot pressure measurement. 2. Materials and methods A retrospective review of the gait laboratory service of our hospital was conducted, focusing on the ambulatory 0966-6362/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0966-6362(03)00072-9