Effects of Foot Posture on Fifth Metatarsal Fracture Healing: A Finite Element Study Emmanuel Brilakis, MD, MSc 1 , Evaggelos Kaselouris, MSc 2 , Frank Xypnitos, MD, MSc, PhD 3 , Christopher G. Provatidis, PhD 4 , Nicolas Efstathopoulos, MD, PhD 5 1 Senior Resident, Second Department of Trauma and Orthopaedics, National and Kapodistrian University of Athens, “Konstantopoulion” General Hospital of Nea Ionia, Athens, Greece 2 Associate Specialist, National Technical University of Athens, School of Mechanical Engineering, Mechanical Design and Control Systems Section, Zografou Campus, Greece 3 Senior Fellow, Department of Trauma and Orthopaedics, The James Cook University Hospital, Middlesbrough, UK 4 Professor, National Technical University of Athens, School of Mechanical Engineering, Mechanical Design and Control Systems Section, Zografou Campus, Greece 5 Associate Professor, Second Department of Trauma and Orthopaedics, National and Kapodistrian University of Athens, “Konstantopoulion” General Hospital of Nea Ionia, Athens, Greece article info Level of Clinical Evidence: 5 Keywords: injury Jones fracture peroneus brevis surgery torsion trauma abstract The goal of this study was to evaluate the effects of maintaining different foot postures during healing of proximal ﬁfth metatarsal fractures for each of 3 common fracture types. A 3-dimensional (3D) ﬁnite element model of a human foot was developed and 3 loading situations were evaluated, including the following: (1) normal weightbearing, (2) standing with the affected foot in dorsiﬂexion at the ankle, and (3) standing with the affected foot in eversion. Three different stages of the fracture-healing process were studied, including: stage 1, wherein the material interposed between the fractured edges was the initial connective tissue; stage 2, wherein connective tissue had been replaced by soft callus; and stage 3, wherein soft callus was replaced by mature bone. Thus, 30 3D ﬁnite element models were analyzed that took into account fracture type, foot posture, and healing stage. Different foot postures did not statistically signiﬁcantly affect the peak-developed strains on the fracture site. When the fractured foot was everted or dorsiﬂexed, it developed a slightly higher strain within the fracture than when it was in the normal weightbearing position. In Jones fractures, eversion of the foot caused further torsional strain and we believe that this position should be avoided during foot immobilization during the treatment of ﬁfth metatarsal base fractures. Tuberosity avulsion fractures and Jones fractures seem to be biomechanically stable fractures, as compared with shaft fractures. Our understanding of the literature and experience indicate that current clinical observations and standard therapeutic options are in accordance with the results that we observed in this investigation, with the exception of Jones fractures. Ó 2012 by the American College of Foot and Ankle Surgeons. All rights reserved. Fractures of the ﬁfth metatarsal are the most common metatarsal fractures in children over 5 years of age and adults. Approximately 45% to 70% of all metatarsal fractures involve the ﬁfth metatarsal (1–4), and the incidence of this injury is estimated at 1.8 per 1000 persons each year (5). These fractures can be classiﬁed into 3 types, namely tuberosity avulsion fractures, fractures at the metaphyseal-diaphyseal junction (Jones fractures), and shaft stress fractures (6,7). Various studies have evaluated the etiology of each type of ﬁfth metatarsal fracture, as well as the best therapeutic options (8–13). As far as tuberosity avulsion fractures are concerned, if the injury involves large displaced intra-articular fragments, surgical manage- ment is required (14), whereas conservative management is the common treatment modality of all nondisplaced or minimally dis- placed fractures. Treatment options are weightbearing as tolerated in a stiff-soled shoe, plaster cast, or elastic dressing (8,14). Although the prognosis of the conservative treatment of avulsion fractures is good and nonunions are uncommon, recovery can take up to 6 months or longer (15). Fractures at the metaphyseal-diaphyseal junction, also called Jones fractures, are named after Sir Robert Jones (16). These are often nondisplaced fractures and their treatment is controversial. Various experts recommend either weightbearing or non- weightbearing in a short leg cast as well as open reduction and internal ﬁxation with lag screws (17). Shaft stress fractures are considered pathological fractures that occur mainly in athletes (14), although they can also occur in patients with poor bone stock. These are commonly associated with repetitive distraction forces (17). If the patient is a competitive athlete or if the fracture is displaced (more than 3 mm) or angulated (more than 10  dorsal or plantar), surgical intervention may be required. Otherwise, nonsurgical management is followed and consists of non-weightbearing immobilization for up to 3 months. Elastic dressing, a posterior splint, short leg cast, or hard plastic cast shoe have also been proposed therapies for this injury, even though they pose problems because of their tendency for nonunion, and patients who disregard the postoperative Financial Disclosure: None reported. Conﬂict of Interest: None reported. Address correspondence to: Emmanuel Brilakis, MD, MSc, 18 str. Aristophanous, 18533 Piraeus, Greece. E-mail address: emmanuel.brilakis@gmail.com (E. Brilakis). 1067-2516/$ - see front matter Ó 2012 by the American College of Foot and Ankle Surgeons. All rights reserved. http://dx.doi.org/10.1053/j.jfas.2012.08.006 Contents lists available at ScienceDirect The Journal of Foot & Ankle Surgery journal homepage: www.jfas.org The Journal of Foot & Ankle Surgery 51 (2012) 720–728