CASE 55 triplane and Tillaux fractures
- Can you describe the radiographs?
These are AP and lateral radiographs of the left ankle in a skeletally immature patient, showing a triplane fracture.
- Can you describe the fracture in more detail?
Triplane fractures are complex intra-articular injuries with a fracture in all three planes (coronal, axial, saggital), and are the result of an external rotation type injury. The epiphysis is fractured in the saggital plane, and is therefore best visual- ised on the AP radiograph. The physis itself is disrupted in the axial plane. Finally, the metaphysis is fractured in the coronal plane and the eponymous Thurstan Holland sign/fragment is best seen on the lateral view.
- At what age do these injuries occur and why?
These injuries are seen in early adolescence, where the physeal fusion starts cen- trally, then medially and finally extends posterolaterally before finishing with the anterolateral portion.
- Through which zone of the physis does the fracture occur?
Physeal fractures most commonly occur through the hypertrophic zone. This is the weakest portion of the physis due to the increase in chondrocyte size and subse- quent reduction in matrix volume.
- How would you manage the injury seen in the radiographs?
This is an intra-articular injury which may require open reduction and internal fixa- tion. I would want to assess for an articular step-off with a CT scan, as the radio- graphs may underestimate the injury. Fractures with displacement <2 mm can be
managed conservatively in a below knee, non-weight bearing cast, with vigilant follow-up to observe for displacement.
Fractures with intra-articular displacement require either closed (or open reduc- tion if necessary) in theatre, followed by internal fixation. Closed reduction would consist of reversing the deforming force, and therefore reduce with internal rota- tion. My preferred choice of fixation would be with two cannulated screws, one in the epiphyseal fragment from medial to lateral and one in the Thurstan Holland fragment from anterior to posterior. I would then place the patient in a below knee plaster of Paris backslab in theatre and instruct the parents and the child to remain non-weight bearing for at least 4 weeks whilst the fracture heals.
- How do these injuries differ from a Tillaux fracture?
Both the triplane and Tillaux fractures occur in early adolescence. The Tillaux frac- ture is an avulsion of the Chaput tubercle, where the anterior inferior tibiofibular ligament inserts onto the anterolateral portion of the epiphysis. The Tillaux fracture is intra-articular with a Salter–Harris type III component similar to that seen in the triplane, except that it does not extend into the metaphysis. Both injuries may require reduction and internal fixation if sufficiently displaced.