Foot and Ankle Surgery 17 (2011) e40–e42 Contents lists available at ScienceDirect Foot and Ankle Surgery journal homepage: www.elsevier.com/locate/fas Case report Closed posterior subtalar dislocation without any associated fracture: A case report and review of the literature Kamal Bali a,*, Vishal Kumar a, Kishan Bhagwat a, Saurabh Rawall b a b Department of Orthopaedics Surgery, PGIMER, Chandigarh 160012, India Departement of Orthopedics, AIIMS, New Delhi, India A R T I C L E I N F O A B S T R A C T Article history: Received 7 January 2011 Received in revised form 20 April 2011 Accepted 28 April 2011 Pure posterior subtalar dislocation without any medial or lateral displacement of foot is extremely rare and hardly reported in the literature. Such an injury is more likely to be open and associated with fractures of the surrounding bones of the foot. Here we report a rare case of closed pure posterior subtalar dislocation without any associated fracture. We discuss in detail the mechanism of such an injury and highlight the importance of prompt closed reduction and early mobilization to ensure a satisfactory long term outcome. ß 2011 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved. Keywords: Subtalar dislocation Talus Navicular Fracture Posterior 1. Introduction Subtalar dislocation represents an uncommon injury, accounting for approximately 1–2% of all joint dislocations [1]. First described in 1811 by Judey and Dufaurest, the subtalar dislocation, also referred to as a subastragalar or peritalar dislocation, involves the disruption of the talocalcaneal and talonavicular joints, while the calcaneocuboid joint remains intact [2,3]. Subtalar dislocation is commonly accompanied by fractures of the malleoli, talus, or fifth metatarsal and by a rotational component of the subtalar joint. Subtalar dislocation can occur in any direction and produces significant deformity. Posterior subtalar dislocation is extremely rare, forming <1% of all subtalar dislocations [4]. We here report a rare case of posterior subtalar dislocation in a young adult. The injury was not associated with any fracture of any of the foot bones which makes the report all the more rare. We also discuss in detail the pathogenesis of such an injury and the management options for an orthopedic surgeon when encountered with such a rare injury. 2. Case report A 33-year-old man presented with pain and deformity in his right ankle following a motorcycle accident. General physical examination did not reveal any other injury and the patient was * Corresponding author. Tel.: +91 9872448458. E-mail address: kamalpgi@gmail.com (K. Bali). found to be hemodynamically stable. On local examination, the ankle was found to be fixed in plantar flexion and revealed a diffuse swelling. Anteriorly, a bony prominence was appreciable and felt proximal to the navicular on palpation. The dorsalis pedis artery pulse was not palpable due to soft tissue swelling, but the sensations to light touch were intact and capillary refill in the toes was normal. The patient was unable to actively move the ankle and reported severe pain when attempting passive movements. Radiographs demonstrated dislocation of both the talonavicular and talocalcaneal joints (Figs. 1 and 2). The calcaneus was displaced posteriorly with no medial or lateral displacement. No fracture of any bones of the foot was appreciable on the X-rays. A diagnosis of posterior subtalar dislocation was thus made. Closed reduction under sedation was performed by longitudinal manual foot traction. With the right knee flexed and a countertraction applied to the leg, a firm digital pressure over the head of the talus was applied as the ankle was plantar flexed and then dorsiflexed. The reduction was associated with an audible clunk. Post-reduction radiographs revealed a congruent reduction of the subtalar and talonavicular joints. The dorsalis pedis pulse returned to normal. The ankle was immobilized in a short leg cast for 3 weeks. Computed tomography (CT) examination after reduction did not show any osteochondral fracture or intraarticluar fragment. Progressive active and passive range of motion exercises of the ankle was permitted after 3 weeks post reduction. At 4 weeks the patient was started on partial weight bearing with crutches and full weight bearing was allowed at 8 weeks. At the last follow-up after 24 months, the patient was ambulatory and did not have any pain. The ankle’s active range 1268-7731/$ – see front matter ß 2011 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.fas.2011.04.005 [()TD$FIG] [()TD$FIG] K. Bali et al. / Foot and Ankle Surgery 17 (2011) e40–e42 e41 Fig. 3. Lateral radiographs after 2 years of follow up. of motion measured 158 in dorsiflexion and 358 in plantar flexion. No instability at the ankle on joint stress tests was noted. The subtalar movements, although restricted, are painless without any signs or symptoms of subtalar joint problems. Fresh radiographs (Fig. 3) were within normal limits. Magnetic resonance imaging also did not show any evidence of avascular necrosis of the talus. 3. Discussion Fig. 1. Lateral radiograph of right foot with ankle showing a true posterior subtalar dislocation. The calcaneus and the midfoot is displaced posteriorly while tibiotalar joint maintains normal angulation. [()TD$FIG] Fig. 2. Antero-posterior radiograph showing no lateral or medial displacement of foot and confirming the diagnosis of pure posterior subtalar dislocation. The subtalar dislocation occurs through the disruption of 2 separate bony articulations, the talonavicular and talocalcaneal joints [1]. In 1853, Broca [5] classified subtalar dislocation for the first time into 3 different dislocation patterns-medial, lateral, and posterior-according to the direction of the foot in relation to the talus. Anterior subtalar dislocation was added by Malgaigne and Burger in 1855 [5]. The medial dislocation, sometimes referred to as an ‘‘acquired clubfoot,’’ is the most common of all subtalar dislocations, comprising approximately 80–85% of cases [6]. The lateral also known as an ‘‘acquired flatfoot,’’ is the second most common subtalar dislocation, occurring in 15–20% of dislocations [6]. First described in 1907 by Luxembourg, the posterior dislocation accounts for <1% of all subtalar dislocations [4]. This has rarely been described in the literature. The instances of posterior subtalar dislocation described in the literature were accompanied by a rotational component and were either open injuries, or were not documented radiographically [7,8]. Most commonly, subtalar dislocation occurs in active young men as a result of a high-energy trauma such as a fall from a height or a motor vehicle accident [9]. It is commonly accompanied by fractures of the malleoli, talus, or fifth metatarsal. Our patient was also an active 33-year-old man with no comorbidities or previous fracture or joint dislocation. Excessive plantar flexion is the main cause of posterior subtalar dislocation, whereas dorsiflexion leads to anterior subtalar dislocation. Inokuchi et al. [5,9] suggest that the type of subtalar dislocation varies depending on the position of foot at the time of injury. Supination or pronation of the foot leads to medial or lateral displacement, respectively. Usually subtalar dislocation occurs with an associated rotational component. To our knowledge, barring the study by Camarda et al. [10], most of the posterior subtalar dislocations described to date have a medial or lateral displacement [4]. In our case, there was no rotational component, suggesting that the trauma was in pure hyperplantar flexion; the foot was fixed in plantar flexion with no rotation of the calcaneus. Pure hyperplantar flexion can lead to a progressive subtalar ligament weakening that might result in a complete ligament e42 K. Bali et al. / Foot and Ankle Surgery 17 (2011) e40–e42 rupture if the plantar flexion force is prolonged. This could be observed in the presence of good bone quality especially if the force is applied distally at the navicular bone. Pure posterior dislocations are extremely rare. One of the reasons behind this could be the inherent instability of these dislocations because the talus is balancing on two points, the dorsum of the navicular and the previous facet of the calcaneus [5]. As such these dislocations can easily convert to medial subtalar dislocations. Also there is a possibility of spontaneous reduction especially in cases with posterior subtalar subluxations. Such injuries are liable to be missed as the radiographs are almost always within normal limits. A high index of suspicion is thus necessary in patients presenting with pain and soft tissue swelling with a typical mechanism of injury (pure hyperplantar flexion). Appropriate management includes rehabilitation after a period of immobilization for a few weeks. Lateral and anteroposterior radiographs of the foot are diagnostic of posterior subtalar dislocation. On lateral radiographs, the head of the talus is perched atop the navicular, and the posterior portion of the talus should be in contact with the posterior subtalar facet of the calcaneus [5]. According to Inokuchi et al. [5], the frontal view should show no significant medial– lateral displacement or rotation of the foot. These typical radiographic features were present in our case. Immediate reduction under anesthesia is recommended to avoid soft tissue complications and reduce the chances of avascular necrosis of the talus as the blood supply to it is from distal to proximal. Medial and lateral dislocations may require an open reduction because of soft tissue interposition or a bony block. With posterior subtalar dislocation, reduction can be achieved with no difficulty by manual traction even if an avulsion fracture of the posterior malleolus occurs [11]. The reduction should be performed with the knee kept slightly flexed and a countertraction performed by the leg. At this point, ankle traction is applied, and a firm digital pressure over the head of the talus is performed from anterior to posterior, passing through plantar flexion to dorsiflexion. The reduction should be associated with an audible clunk. A radiograph should be performed to ensure the reduction of the dislocation and to exclude any iatrogenic fracture. CT or MRI scans of the ankle and foot should be done post-reduction to evaluate the talus and sub-talus articular surface to rule out any osteochondral fracture or intraarticular fragment. As much as 80% of subtalar dislocations have restriction in motion after healing, and 50–80% have radiographic evidence of post-traumatic subtalar arthritis [12]. Open dislocations and those associated with significant swelling are initially immobilized in a posterior splint to aid in skin evaluation. Subsequently and following those successfully reduced in a closed fashion, the patient is placed nonweight bearing into a below-the-knee cast for 4 weeks, followed by progressive mobilization and rehabilitation. Good functional outcomes for closed posterior subtalar dislocation have been uniformly reported in the literature [4,5,9,10]; however, the prognosis may be poorer when posterior subtalar dislocation is associated with other lesions such as soft tissue injury, intra-articular fracture, extra-articular fracture, infection, osteonecrosis, and chronic subtalus instability [8,13]. Subtalar arthrodesis is an option for patients with refractory subtalar pain and instability. Buckingam et al. [14] and Zimmer et al. [6] recommend immobilizing the ankle for >4 weeks, while DeLee and Curtis [2] found that casting for 3 weeks leads to better outcomes. In uncomplicated subtalar dislocations, subtalar joint stiffness can be minimized by avoiding immobilization longer than 4 weeks [13]. The period of immobilization is thus controversial as per the available literature. However we believe that prompt reduction and early mobilization is the key to satisfactory long term outcome. The joint is inherently stable once reduction has been achieved. No recurrent subtalar dislocation has been described in the literature to date, suggesting that residual subtalar joint laxity does not represent a risk for future recurrent subtalar dislocation. To conclude, subtalar dislocation is a rare entity and posterior dislocation variety is even rarer. Although most commonly it is associated with fractures of the surrounding bones, it can present as a pure dislocation. The mechanism of injury is by pure hyperplantar flexion of the foot. A prompt reduction ensures that the talus doesn’t end up in avascular necrosis while an early mobilization increases the likelihood of satisfactory long term outcome. Conflicts of interest statement The authors have no conflicts in interest while working on this project. Disclosure All the authors were fully involved in the study and preparation of the manuscript and that the material within has not been and will not be submitted for publication elsewhere. No funds were received in support of this study. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript. References [1] Perugia D, Basile A, Massoni C, Gumina S, Rossi F, Ferretti A. Conservative treatment of subtalar dislocations. Int Orthop 2002;26(1):56–60. [2] DeLee JC, Curtis R. Subtalar dislocation of the foot. J Bone Joint Surg Am 1982;64(3):433–7. [3] Bohay DR, Manoli II A. Subtalar joint dislocations. Foot Ankle Int 1995;16(12):803–8. [4] Krishnan KM, Sinha AK. True posterior dislocation of subtalar joint: a case report. J Foot Ankle Surg 2003;42(6):363–5. [5] Inokuchi S, Hashimoto T, Usami N. Posterior subtalar dislocation. J Trauma 1997;42(2):310–3. [6] Zimmer TJ, Johnson KA. Subtalar dislocations. 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