Abstract
We describe a rare case of an isolated Tillaux-Chaput fracture of the ankle in an adult patient. This injury is an avulsion fracture of the anterolateral tibial plafond (Chaput’s tubercle) caused by external rotation of the ankle. Tillaux fractures classically occur in adolescents as Salter-Harris III physeal injuries and are less common in skeletally mature adults. Diagnosing this fracture in an adult can be challenging, as the small anterolateral tibial fragment may be subtle or easily overlooked on standard radiographs. In our case, advanced imaging with computed tomography (CT) was crucial for confirming the fragment and planning surgical management, consistent with recent evidence that CT scans significantly improve detection and preoperative planning for adult Tillaux-Chaput fractures. The patient underwent open reduction and internal fixation to achieve anatomic restoration of the distal tibial articular surface. This case highlights the importance of maintaining a high index of suspicion for Tillaux fractures in adult ankle injuries. It underscores the role of CT imaging and timely surgical intervention to prevent chronic instability and post-traumatic arthritis.
Introduction
Tillaux fractures are avulsion-type fractures of the anterolateral tibial plafond (Chaput’s tubercle) caused by the pull of the anterior inferior tibiofibular ligament (AITFL) during forceful external rotation of the foot. This injury pattern is well recognized in adolescents as a Salter-Harris III fracture of the distal tibial epiphysis. Tillaux fractures typically occur in 12- to 14-year-olds during the unique 18-month period when the distal tibial physis closes asymmetrically (central and medial portions close first, leaving the lateral portion vulnerable). , Once the tibial growth plate is fused, the AITFL usually fails by ligamentous rupture rather than by bony avulsion, making a Tillaux-Chaput fracture (an adult Tillaux fracture) extremely unusual without any data on incidence rates in the adult population.
Diagnosing a Tillaux-Chaput fracture can be challenging. The bony fragment at the anterolateral tibial plafond is often small and may be difficult to appreciate on a routine ankle radiograph series. ,, Such injuries can be easily overlooked or misinterpreted as a simple ankle sprain. Advanced imaging is invaluable for diagnosis. Computed tomography (CT) can confirm the presence of a Tillaux-Chaput fragment, assess its size and displacement, rule out concomitant fractures, and guide optimal management. Missed or untreated Tillaux-Chaput fractures can lead to poor outcomes with chronic anterolateral ankle instability, malunion with an intra-articular step-off, early osteoarthritic changes, and restricted ankle motion due to pain. Prior reports have emphasized that anatomic reduction of the avulsed fragment and restoration of the articular surface are necessary to prevent these complications. The unique challenges in this case underscore the clinical significance of maintaining awareness of Tillaux-Chaput fractures in adults. This case highlights the diagnostic, imaging, and biomechanical considerations relevant to this rare injury and adds to the limited body of literature on adult Tilllaux-Chaput fractures.
Case report
A 71-year-old female presented to a local hospital for right ankle pain after a ground-level fall. She stated that she was rising from a chair at home, lost her balance, and twisted her ankle, causing her to fall. The patient complained of immediate right ankle pain and inability to bear weight on her right lower extremity after injury. Her past medical history included bladder cancer and chronic kidney disease. On examination, she was tender over the anterolateral and posterior aspects of the ankle, with no significant swelling or ecchymosis. Active ankle dorsiflexion and plantarflexion were limited by pain. Laxity was present on the anterior drawer test. The patient ambulated with a walker at baseline prior to injury and was able to perform her ADLs independently. She was admitted to the hospital as her creatinine was 6.6, requiring hemodialysis. She sustained no additional injuries related to her fall.
Anteroposterior, lateral, and mortise radiographs of the right ankle were obtained in the emergency department. The tibiotalar joint appeared to be aligned anatomically without significant widening, visible fractures, or bony abnormalities ( Fig. 1 -A, 1 -B, 1 -C). Due to her pain on exam and inability to bear weight, computed tomography (CT) of the right ankle was performed, which demonstrated a displaced Chaput fracture and nondisplaced posterior malleolus fracture ( Fig. 2 -A, 2 -B, 2 -C). The Chaput fragment measured 1.3 cm by 0.6 cm in size and was displaced 6 mm laterally. The posterior malleolus fracture was classified as a Bartoníček/Rammelt Type II fracture. The posterior malleolus fragment measured 0.97 cm or approximately 26% of the tibial plafond articular surface on the sagittal view ( Fig. 2 -D).
Non-weight-bearing Right Ankle Radiographs. ( Fig. 1 -A) Anteroposterior radiograph of the right ankle ( Fig. 1 -B) Lateral radiograph of the right ankle ( Fig. 1 -C) Mortise radiograph of the right ankle (image sourced from patient’s report).
Noncontrast Computed Tomography of Right Ankle. ( Fig. 2 -A) Axial cut at the level of the plafond showing Chaput and posterior malleolus fracture, ( Fig. 2 -B) Coronal cut of anterior plafond, ( Fig. 2 -C) Sagittal cut, ( Fig. 2 -D) Posterior malleolus size on sagittal cut (image sourced from patient’s report).
Informed consent for surgical treatment was obtained from the patient. The patient was positioned supine, and an anterolateral ankle approach centered over the tibiotalar joint was used to expose the Chaput fragment ( Fig. 3 -A, 3 -B). The superficial peroneal nerve was visualized, and care was taken to protect it with retraction. Direct visualization of the anterolateral tibiotalar joint revealed the Chaput fragment and a syndesmotic injury involving the AITFL, which was torn substantially.
– Surgical Approach. ( Fig. 3 -A) Anterolateral incision ( Fig. 3 -B) Anterolateral Surgical Exposure of Chaput Fragment (image sourced from patient through informed consent).
The Chaput fragment was anatomically reduced with a dental pick, and a Kirschner wire (K-wire) was placed through the fragment perpendicular to the fracture line ( Fig. 4 ). A cannulated drill bit was used to predrill the first cortex. A headed 4.0 mm cannulated lag screw with a washer was then placed over the K-wire and tightened to compress the fragment ( Fig. 5 ).
– Preliminary fixation of Chaput Fragment with Kirschner Wire (image sourced from patient through informed consent).
– 4.0 mm screw fixation of Chaput fragment and Suture Tape in AITFL (image sourced from patient through informed consent).
Attention was then directed to the damaged AITFL. A 1.3 mm Arthrex SutureTape was passed through the AITFL with a grasping stitch Fig. 7 . The sutures were tensioned, and a 3.5 mm Arthex SwiveLock anchor was used to anchor the suture into the distal tibia proximal to the Chaput fragment’s fracture line ( Fig. 6 ).
–AITFL secured to the distal tibia with SwiveLock Anchor (image sourced from patient through informed consent).
