A Review of Adolescent Triplane Fractures of the Distal Tibia
“Triplane fractures of the distal tibia are multiplanar fractures that violate the tibia and joint space in three configurations – the axial, sagittal and frontal planes…”
case
A 17-year-old male without significant past medical history presented to the pediatric emergency department complaining of right ankle pain after a soccer injury. The injury occurred when he attempted to slide tackle an opponent, causing a twisting movement in his right lower extremity. He had no head strike or loss of consciousness. He felt immediate pain and was unable to weight bear afterwards. He denied numbness and tingling. He had no other injuries. His vitals were within normal limits. His physical exam was notable for diffuse right ankle tenderness with generalized edema and limited range of motion secondary to pain. The skin was intact, and he was neurovascularly intact distally. Xrays of the right ankle, foot, tibia/fibula were read as: “triplane fracture of the distal tibia with approximately 1 cm lateral and 7 mm anterior displacement of the epiphyseal fragment. The fracture also involves the medial malleolus. There is disruption of the ankle mortise and a large amount of soft tissue swelling particularly anteriorly. “ The orthopedic surgery team was consulted for further evaluation and management.
Figure 1: Initial xray imaging for the 17-year-old patient in the case report above.
discussion
Triplane fractures of the distal tibia are multi-planar fractures that violate the tibia and joint space in three configurations – the axial, sagittal and frontal planes. This specific type of fracture is traditionally characterized by the number of fracture fragments produced. The most common triplane fracture is a 2-part configuration, followed by 3-part and then 4-part.
Figure 2: Fracture planes of triplane distal tibia fractures; A: 2-part triplane ankle fracture B: 3-part triplane ankle fracture; image obtained from Ankle Injuries in the Pediatric Emergency Department
This fracture pattern is seen almost exclusively in adolescents and accounts for approximately 5-15% of intra-articular pediatric ankle fractures with the mean age being 13-14 years old. This is due to a multitude of factors, the most significant being the epiphyseal closing pattern as the physis transitions from skeletal immaturity to maturity. As such, these fractures are often referred to as “transitional fractures.” The distal tibia physis closure begins centrally and then transitions to anteromedially, to posteromedial, and lastly to the most lateral edge of the epiphysis. Because of this, the epiphysis is left vulnerable to fractures in the face of high rotational force, which is the most common mechanism described with triplane fractures of the distal tibia, though there have been studies demonstrating that these fractures also occur with lower energy, non-rotational forces as well.
The transition to skeletal maturity and subsequent closing of the distal tibia epiphysis usually occurs between ages 12-15 years old and takes approximately 18 to 20 months. This timing is variable and largely dependent on the onset of puberty. This results in timing and overall incidence variability between sexes, with boys demonstrating a higher incidence and a later age presentation compared to girls presenting with the same injury.
Figure 3: Epiphyseal closure pattern of the distal tibia; image obtained from The Pediatric Triplane Ankle Fracture
CLINICAL PRESENTATION
History
The history will likely reveal an adolescent presenting to the emergency department with ankle pain and inability to bear weight, most frequently after a twisting/rotational type injury. These injuries are often associated with sporting activities but can occur with lower magnitude, nonrotational mechanisms as well. As mentioned previously, there is a higher incidence in boys than girls and the patient will likely be between the ages of 12-17 years old.
Physical Examination
The physical exam will demonstrate edema and ecchymosis of the affected ankle, but gross instability is rare. Commonly, there will be point tenderness to the physis in a circumferential manner. A thorough neurovascular exam is required but is rarely revealing. The physical exam will be indicative of fracture but is nonspecific to triplane fractures and should always be followed by imaging.
MANAGEMENT
Imaging
Imaging is necessary to further classify the fracture. When evaluating the ankle via x-ray imaging, it is important to obtain at least three views – AP, mortise and lateral. Although useful in assessing the question of fracture, x-ray imaging frequently misses and misclassifies triplane fractures as each view typically shows only a single fracture plane. The mortise view is the most useful for evaluating the sagittal fracture line and degree of articular displacement. This is particularly useful for prognostication and management options.
Computed tomography (CT) is the best way to evaluate a triplane fracture. In a 2015 study evaluating the role of CT in diagnosis and treatment of distal tibia fractures with intra-articular involvement, it was reported that CT imaging revealed a significant number of triplane fractures originally missed with x-ray alone and provided further classification of known triplane fractures that affected the overall management of that fracture. The study demonstrated that CT imaging is essential for identifying the configuration and degree of articular displacement, further highlighting its necessity for both diagnosis and management of triplane fractures of the distal tibia.
MRI does not show clear benefit over CT imaging in diagnosis or classification of triplane distal tibia fractures. The additional cost, time and resources required for MRI make CT imaging the preferred imaging modality for further evaluation of these complex fractures.
Operative vs non-operative approach
Management is largely dependent on the degree of fracture fragment displacement. Non-displaced or minimally displaced fractures with less than 2 mm of displacement can be managed nonoperatively with a long-leg immobilization cast and close orthopedic follow up. Reduction can be attempted in order to decrease overall displacement and attempt nonoperative management. The reduction maneuver for the classic triplane tibial fracture (2 to 3 part with >2 mm displacement) is that of axial traction on the ankle and internal rotation of the foot. Post reduction CT films should be obtained to further categorize the degree of residual displacement and help guide operative verses nonoperative management. Serial x-rays should be obtained to assess whether or not the reduction holds through the immobilization period. It is important to note that fractures with greater than 3 mm of displacement are less likely to undergo successful closed reduction and will likely require surgical reduction despite attempted reduction in the emergency department.
Fractures with post-reduction displacement greater than 2 mm or those that lost reduction during a period of attempted nonoperative management require surgery/open reduction. This is typically achieved by placing screws parallel to the physis and as perpendicular to the fracture lines as possible to allow for the greatest degree of compression, thus restoring congruity of the articular surface.
After anatomical reduction is achieved, the patient is placed in a non-weight bearing long-leg cast for 3-4 weeks followed by a short leg cast that allows for some weight bearing. The patient should have close orthopedic follow up throughout this time period.
OUTCOMES
Triplane ankle fractures that receive adequate anatomical reduction, defined as less than 2 mm of residual displacement, have excellent outcomes whether managed operatively or non-operatively.
Long term complications of triplane fractures of the distal tibia include physeal damage and premature closure of the epiphysis. Premature closure occurs in approximately 7%-21% of cases and is associated most significantly with the degree of residual displacement. Although this is a relatively high percentage, significant growth-arrest and tibial shortening are unlikely to result, as these injuries occur close to skeletal maturity. The second concern with triplane fractures is degenerative changes in the ankle which may lead to chronic pain. A 2014 study that used validated outcome tools (Foot and Ankle Outcomes Score/FAOS and Marx Activity Scale/MAS) to evaluate functional outcome after triplane fracture of the distal tibia demonstrated that patients had an overall good long-term functional prognosis when appropriate anatomical reduction was achieved. Residual displacement of greater than 2 mm was associated with degenerative changes and poor long-term results.
cASE RESOLUTION
The patient underwent procedural sedation with ketamine for reduction in the emergency department. Repeat CT of his right ankle showed: “re-demonstration of triplane fracture involving the distal tibia medially. As noted radiographically, there is 7 mm of anterior displacement of the epiphyseal fragment and 8 mm of lateral displacement with approximately 6 mm of gap at the articular surface in the coronal plane. Non-displaced Salter-Harris type IV fractures of the medial and posterior malleoli are also present. “ The patient was placed in a long leg cast and was discharged home with pain control as well as instructions to ice, elevate and follow up with the pediatric orthopedic surgeon in one week. He later required open reduction and internal fixation of this right ankle.
Figure 4: CT imaging of the distal tibia triplane fracture after attempted reduction in the emergency department, still demonstrating significant displacement (>2 mm) necessitating surgical management (seen in Figure 5)
Figure 5: Post-operative imaging
Take-aways
Suspect possible triplane distal tibia fracture in adolescents who present to the emergency department complaining of ankle pain with inability to weight bear, particularly after a reported sporting or rotational injury
When obtaining imaging in the emergency department, it is important to obtain 3-view x-rays to assess for degree of displacement (mortise view most useful for this). When triplane fractures are suspected on x-ray, follow up x-ray imaging with CT imaging to further classify and guide treatment options; it is helpful to involve orthopedic colleagues if available
Reduction maneuver for classic triplane distal tibia fracture: axial traction on the ankle with internal rotation of the foot; follow with post-reduction CT imaging
If anatomical alignment is achieved after closed reduction (less than 2 mm of residual displacement) then the patient can be placed in a non-weight bearing long-leg immobilization cast and discharge home with close orthopedic follow up
If greater than 2 mm of residual displacement exists after attempted reduction, then the patient will likely require surgery for best patient outcomes
AUTHOR: Dr. Elizabeth Lanata, MD, is a current fourth year emergency medicine resident at Brown Emergency Medicine Residency.
FACULTY REVIEWER: Dr. Michelle Myles, MD, is an attending physician/clinician educator at Brown Emergency Medicine.
references
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