Abstract
This case report highlights two critical aspects of a complex ankle injury. It first presents a specific and rare injury pattern: a Bosworth fracture-dislocation occurring in conjunction with a tibial pilon fracture. Most consequentially, the key lesion was not identified initially and, therefore, was not treated promptly. This diagnostic failure directly led to severe soft-tissue complications, which compromised the surgical plan, delayed definitive treatment, and increased the risk of a poor outcome.
Introduction
The Bosworth fracture-dislocation is a rare and often neglected irreducible ankle injury, defined by the entrapment of the fibula posterior to the posterolateral ridge of the tibia. This specific pathoanatomy makes the dislocation mechanically irreducible by closed means. Consequently, when this injury is misdiagnosed and treated as a normal ankle fracture-dislocation, repeated reduction attempts are futile and may cause significant iatrogenic soft-tissue damage, leading to severe complications.
While its rarity is documented, the current literature lacks guidance on managing the severe soft-tissue complications that arise from its inherent diagnostic difficulty. This case report highlights the diagnostic pitfalls specific to this hybrid injury and details the deleterious consequences on the soft-tissue envelope, offering essential management lessons regarding surgical timing and staged protocols.
In the majority of cases, this injury pattern is described as a fracture-dislocation of the ankle. However, in exceptionally rare instances, a Bosworth lesion (or displacement) occurs in the setting of a complex tibial pilon fracture. This association involves extensive posterior malleolar fractures (Bartoníček–Rammelt type 3) that extend into the posteromedial tibial plafond, crossing the anatomical dividing line from a simple ankle fracture to a partial pilon fracture. The mechanical interplay in this injury pattern typically involves a high-energy axial load causing the pilon fracture, combined with a supination-external rotation force leading to the Bosworth lesion. Anatomically, the tibial comminution may hide the fibular displacement, while the incarceration of the fibular fragment within the pilon fracture line creates a mechanical block. The first such cases of a Bosworth fracture associated with a posterior pilon fracture were recorded in 2017 by Cappuccio et al. and Bartoníček et al. , . To date, only a handful of subsequent cases have been reported, with a total of approximately five such injuries documented in the literature.
This article aims to report another case of this highly unusual injury—a Bosworth lesion in a tibial pilon fracture—which, moreover, was initially presenting a significant diagnostic challenge inherent to such complex trauma. Framed as a diagnostic challenge rather than a simple oversight, this complexity often leads to unsuccessful reduction attempts before advanced imaging confirms the irreducible nature of the lesion.
Clinical case report
A 63-year-old man presented to the emergency department on November 13, 2023, at 13:00 with acute pain and deformity in his right ankle following a low-velocity fall from a standing height. Clinical examination revealed a severely swollen ankle with marked axial deviation. Initially, there were no signs of skin compromise or neurovascular impairment.
Initial radiographs revealed a complex pilon fracture. The anteroposterior view demonstrated an overlap between the distal tibia and the proximal fibular fragment ( Fig. 1A ). On the lateral view, the talus was subluxated but not fully displaced, and the distal fibular fragment was slightly angulated dorsally ( Fig. 1B ).
Emergency room Xray AP view, left-side. Initial radiographs revealed a complex pilon fracture. The anteroposterior view demonstrated an overlap between the distal tibia and the proximal fibular fragment.
Emergency room xray, lateral view, left-side. On the lateral view, the talus was subluxated but not fully displaced, and the distal fibular fragment was slightly angulated dorsally.
At 15:00 , an initial attempt at closed reduction under sedation in the emergency department failed ( Fig. 2A and B ). The patient was then taken to the operating theatre, where a second reduction attempt under general anaesthesia was performed, with apparent success. However, the next morning, a subsequent computed tomography (CT) scan revealed persistent tibiotalar dislocation, necessitating the application of a spanning external fixator .
AP view, left-side after 1st attempt of closed reduction. Xray shows persistent tibiotalar dislocation.
lateral view, left-side after 1st attempt of closed reduction. Xray shows persistent tibiotalar dislocation.
Despite the external fixator, the dislocation persisted, and significant signs of soft-tissue distress began to appear, including worsening oedema and the formation of large fracture blisters (phlyctenae). A repeat CT scan on 16/11/23 showed poor fracture reduction and identified the critical pathology: the proximal fibular fragment was incarcerated in the fracture line between the distal tibia and the posterior tibial fragment, effectively blocking reduction ( Fig. 3A-C ). The scan confirmed a partial posteromedial pilon fracture with an associated Bosworth lesion. By this point, the severe skin damage—including blisters, tense swelling, and areas of dry necrosis—complicated urgent operative planning.
left ankle CT scan on 16/11/23, axial view. The scan confirmed a partial posteromedial pilon fracture with an associated Bosworth lesion. MM: medial malleolus. AL: anterolateral fragment. IF: incarcerated fibula. F: fibula.
3D-CT reconstruction of left ankle (posterior view). We can see the incarcerated fibula in the pilon fracture.
3D-CT reconstruction of left ankle (lateral view). We can see the incarcerated fibula in the pilon fracture.
On 17/11/23 , given the severely compromised soft-tissue envelope, the patient was taken to the operating theatre, where various closed and percutaneous reduction techniques were attempted, including manipulation with a Lambotte hook, increased distraction through the external fixator, and the use of large bone-holding forceps. All indirect reduction attempts were ineffective.
Consequently, open reduction via a direct lateral approach was performed during the same procedure. Incarceration of the proximal fibula fragment within the fracture line of the tibial pilon was confirmed. The fibula was freed by direct reduction using forceps, combined with axial traction and a levering manoeuvre with a periosteal elevator (rugine). A characteristic loud, sharp “click” was heard upon its release.
During the same operation, primary osteosynthesis of the fibula was performed using an anatomical plate and screws. The external fixator was then reapplied, achieving a correct reduction of the tibiotalar joint ( Fig. 4A and B ). The patient showed no neurovascular deficits in the immediate postoperative period.Despite the poor condition of the skin, primary wound closure was achieved, requiring close, regular follow-up. In accordance with standard protocols for major lower-limb trauma and prolonged immobilization, pharmacological venous thromboembolism (VTE) prophylaxis (Low-Molecular-Weight Heparin) was administered daily from admission and continued throughout the postoperative period (6 weeks).
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