Triplane fracture

Last revised by Craig Hacking on 12 Jun 2024

Triplane or triplanar fractures are of the distal tibia only occurring in adolescents. As the physiological closure of the physeal plate begins medially, the lateral (open) physis is prone to this type of fracture. Most authors regard it as a type 4 Salter-Harris fracture.

It comprises of 3 components: 

  • a vertical (sagittal) fracture through the epiphysis

  • a horizontal (axial) fracture through the physis

  • an oblique (coronal) fracture through the metaphysis

As physeal closure has to begin at one end, triplane fractures have occasionally been reported in other sites too, e.g. distal radius 2, proximal tibia 4, distal femur 5.

In adolescents with closing epiphyseal plate(s) they are the most common ankle joint fractures, along with Tillaux fractures.

Symptoms comprise of pain and inability to weight bear after an ankle injury. Possible signs include swelling, localized or referred pain, and ankle deformity.

External rotation and supination is the main mechanism of injury in lateral triplane fractures. The uncommon medial variation usually occurs with an adduction force 9.

Standard ankle series suggested; AP, lateral and mortise (best view to define displacement). Due to the aforementioned characteristics, the fracture typically resembles a:

Small dislocations and the vertical fracture itself are frequently overlooked, and CT is advised if there is concern. 

The imaging modality of choice, permitting identification of;

  • fracture pattern and articular congruity

  • fragment number and orientation/relationship

For the same reasons, CT aids in treatment planning as well 6.

May be used to reveal associated ligamentous injuries, osteochondral fractures and chondral fractures 7.

Treatment options comprise of surgery (e.g. open reduction and internal fixation (ORIF)) or conservative management (e.g. long leg cast immobilization). Physeal arrest may occur in 7% to 21% of cases, rarely leading to angular deformity. The significance of preserving the physis is questionable given the limited remaining growth potential, but patients with greater than 2 years of growth remaining should be followed.

The distinctive term for this fracture was coined by L Marmor in 1970 stemming from it lying in the frontal, lateral, and transverse planes 8.

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