Sean is 13 years old. He was playing basketball when he jumped to score a basket. He landed awkwardly on his ankle, twisting and externally rotating it. He immediately fell to the floor on the court and couldn’t bear weight on it. The swelling and bruising increased, and he attended his local emergency department, where he was told that he had a triplane ankle fracture.
Epidemiology
Although triplane ankle fractures account for only 5-15% of overall paediatric ankle fractures, along with Tillaux fractures, they are the most common ankle fractures in adolescents. This type of fracture represents a unique spectrum of injury that does not fit neatly into the Salter-Harris classification of physeal injury. They occur before the complete closure of the distal tibial physis (hence why they occur in adolescents whose epiphyseal plates are closing) and are classically seen in 10-17-year-olds. They are slightly more common in males.
History
Adolescents with triplane fractures will usually present to the emergency department with a very painful and swollen ankle after a twisting force to the leg during athletic or recreational activities. They are usually very reluctant or unable to weightbear.
Examination
There will often be swelling and bruising with focal or referred pain at the affected ankle, which may be deformed. It is also important to examine skin integrity and the presence of neurologic defects or vascular injuries. Don’t forget to palpate the full length of the fibula to evaluate for a proximal fracture and along the foot for injuries such as a fracture to the base of the 5th metatarsal.
Investigations
AP and lateral ankle X-rays will help evaluate the fracture type. A mortise view, performed with the leg internally rotated approximately 15 degrees to allow better assessment of the articular space, should be included to assess the amount of displacement if this can’t be fully appreciated on the AP view (although in some countries, the AP view is a mortise view).
The triplane fracture on X-ray looks like a Salter-Harris II or III, depending on whether it is a medial or lateral triplane fracture. The fracture is in all three planes, classically looking like a Mercedes sign on CT.
It may be classified as in 2, 3 or 4 parts.
It is important not to miss fibular fractures seen in 50% of triplane fractures. Typically, this spiral fracture pattern is proximal to the physis in children nearing skeletal maturity.
CT scans are not routinely performed in the emergency department but may be organized by the orthopaedic team. Small dislocations and the vertical component of the fracture are not infrequently overlooked. CT is, therefore, often organized to fully delineate the fracture pattern and assess the degree of intra-articular congruity.
Management
In the ED, as with any injury, ensure you prescribe adequate analgesia and provide assistance with non-weight-bearing status, such as a wheelchair or crutches, depending on the child’s ability. Placement in a boot or cast for comfort before definitive treatment by the orthopaedic team is appropriate.
Once the diagnosis is made, ongoing care depends on the degree of displacement. Orthopaedic review to consider conservative management versus operative management is important, as these fractures will often need CT imaging to ensure adequate delineation of the fracture pattern.
Conservative management
Fractures with minimal displacement (<2mm), particularly 2-part triplane fractures, can often be managed with closed reduction and casting. Closed reduction is difficult if the fracture is in 3 or 4 parts.
Post reduction, place in a long leg/above knee cast for 3-4 weeks to control the rotational component of the injury, followed by a further 2-4 weeks in a short leg cast or walking boot to initiate ankle range of movement.
Operative Management
Any triplane fracture with >2mm displacement or that is in 3 or 4 parts is likely to require ORIF (Open Reduction, Internal Fixation). Intra-articular reduction to within 2 mm is required to optimally treat these unique paediatric ankle fractures.
Complications and Risks
Growth Arrest
The main concern for adolescents with triplane fractures is growth arrest, which occurs in 7-21%Â of triplane injuries. Although this is often insignificant, patients with more than two years of growth must be closely followed up.
Ankle Pain and Degeneration
Rare but increased risk with articular step greater than >2mm.
Controversies
As with all things orthopaedic, the debate continues: Should these fractures be managed operatively or conservatively? Though still in preliminary research stages, recent evidence suggests that non-operative treatment of triplane fractures may have comparable clinical and radiographic results to operative treatment. Given the different management options, discussion with the orthopaedic team is advised before discharge.
Things not to miss!
Remember to examine the rest of the child’s lower limb when they present with a painful swollen ankle, as there may be an accompanying fracture.
Ensure that you examine and especially palpate both the foot and the entire length of the fibula.
With rotational forces, proximal spiral fibula fractures and base of 5th metatarsal fractures are relatively common with triplane fractures.
Carefully check and document neurovascular status, as nerve injury can occasionally be associated with spiral fibular fractures.
Sean was found to have a two-part nondisplaced Triplane Fracture. He was placed in an above-knee cast and followed up at his local orthopaedic outpatient clinic.
He had interval X-rays, which showed good healing and no evidence of displacement.
After four weeks, he was switched to a walking boot to encourage early ankle mobilization for another two weeks. He is already looking forward to next year’s basketball season!
References
Schnetzler, Kent A et al. 2008 ‘The Pediatric Triplane Ankle Fracture’ The Journal of the American Academy of Orthopaedic Surgeons 15(12):738-47
Hyman et al., MSK Key https://musculoskeletalkey.com/transitional-ankle-fractures-juvenile-tillaux-and-triplane-fractures/ Accessed at 09/02/20
Beaty JH, Kasser JR. Rockwood and Wilkins’ Fractures in Children. 6th ed. Baltimore, MD: Lippincott Williams & Wilkins; 2006:1105
https://orthoinfo.aaos.org/en/diseases–conditions/ankle-fractures-in-children
Min Ryu, Seung et al. 2017 ‘Is an operation always needed for pediatric triplane fractures?’ Journal of Pediatric Orthopaedics B 27(5):1 · November 2017
https://www.orthobullets.com/pediatrics/4029/triplane-fractures
https://orthoinfo.aaos.org/en/diseases–conditions/ankle-fractures-in-children
