UNCORRECTED PROOF 1 2 A biomechanical analysis of the effect of lateral column 3 lengthening calcaneal osteotomy on the flat foot 4 George A. Arangio a, * , Vikram Chopra b , Arkady Voloshin c , Eric P. Salathe b 5 a Department of Surgery, Division of Orthopedic Surgery, Lehigh Valley Hospital, Allentown, PA, USA 6 b Department of Mathematics and Institute for Biomedical Engineering and Mathematical Biology, Lehigh University, Bethlehem, PA, USA 7 c Department Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA, USA 8 Received 6 March 2006; accepted 12 November 2006 9 10 Abstract 11 Objective. The objective was to examine the hypothesis that increased load on the medial arch in the adult flat foot can be reduced 12 through a 10 mm lateral column lengthening calcaneal osteotomy 10 mm proximal from the calcaneal cuboid joint. 13 Design. A three-dimensional multisegment biomechanical model was used with anatomical data from a normal foot, a flat foot and a 14 foot corrected with a 10 mm lateral column lengthening calcaneal osteotomy. 15 Background. Biomechanical models have been used to study the plantar aponeurosis, medial arch height, subtalar motion, medial 16 displacement calcaneal osteotomy, subtalar arthroereisis and the distribution of forces in the normal and flat foot. 17 Methods. The response of a normal foot, a flat foot and a flat foot with a 10 mm lateral column lengthening calcaneal osteotomy to an 18 applied load of 683 N was analyzed using the biomechanical model. Data for the biomechanical model was obtained from a cadaver foot 19 using the direct linear transformation method. Direct linear transformation uses multiple cameras to determine the spatial location of 20 anatomical landmarks. 21 Findings. Load on the first metatarsal increases to 37% body weight in the flat foot compared to 12% for the normal foot and the 22 moment about the talo-navicular joint increases from 5.6 N m to 21.6 N m. Lateral column lengthening shifts the load toward the lateral 23 column, decreasing load on the first metatarsal to 10% and decreasing the moment about the talo-navicular joint to 8.1 N m. 24 Conclusion. The analysis shows that a 10 mm lateral column lengthening calcaneal osteotomy reduces the excess force on the medial 25 arch in an adult flat foot and adds biomechanical rationale to this clinical procedure. 26 Ó 2006 Published by Elsevier Ltd. 27 Keywords: Biomechanical model; Flat foot; Support distribution; Calcaneal osteotomy; Lateral column lengthening 28 29 1. Introduction 30 Adult acquired flat foot is an acquired deformity charac- 31 terized by medial and plantar rotation of the talus, decrease 32 in the medial arch height, supination and abduction of the 33 forefoot, and increase in the talo-navicular coverage angle. 34 The Achilles tendon may shorten and exert a valgus 35 moment on the calcaneus (Mann, 1993; Goldner et al., 36 1974; Funk et al., 1986). The posterior tibial tendon may 37 weaken and the talo-navicular capsule, the tibio-navicular 38 ligament, the spring ligament complex, the long plantar 39 ligament, the short plantar ligament, and the plantar apo- 40 neurosis may elongate (Deland et al., 2005). The load shifts 41 from the lateral column to the medial column, and the 42 medial arch flattens (Arangio et al., 2000). Giannini et al. 43 (1992) reported abnormal gait in the flat foot patient. 44 Our biomechanical models (Salathe and Arangio, 2002, 45 Phillippy et al., 1997) have been use to study the metatar- 46 sals, plantar aponeurosis, medial arch height, subtalar 47 motion, medial displacement calcaneal osteotomy, subtalar 0268-0033/$ - see front matter Ó 2006 Published by Elsevier Ltd. doi:10.1016/j.clinbiomech.2006.11.004 * Corresponding author. Address: Valley Sports and Arthritis Surgeons, 798 Hausman Road, Suite 100, Allentown, PA 18104-9116, USA. E-mail address: casarangio@aol.com (G.A. Arangio). www.elsevier.com/locate/clinbiomech Clinical Biomechanics xxx (2006) xxx–xxx JCLB 2599 No. of Pages 6, Model 5+ 9 December 2006 Disk Used ARTICLE IN PRESS Please cite this article in press as: Arangio, G.A. et al., A biomechanical analysis of the effect of lateral column ..., J. Clin. Biomech. (2006), doi:10.1016/j.clinbiomech.2006.11.004