DISCUSSION
The radiographs are consistent with a triplane fracture. The patient was referred to an orthopedist and was placed in a short leg cast with no weight bearing for 4 weeks. One week after casting, a follow-up radiograph demonstrated normal alignment of the ankle mortise. At week 5, the patient was placed in an ankle stirrup brace and gradual rehabilitation was prescribed. At approximately 2 months after the injury, the patient had full range of motion of his ankle and resumed normal activities as tolerated.
Triplane fractures are the second most common growth plate injuries encountered. Peak incidence in boys is between ages 13 and 15 years and in girls between ages 12 and 14 years, with an average age range of 10 to 15 years.1 Triplane fractures have been termed transitional fractures since young people are most susceptible to this injury when they are transitioning from skeletal immaturity to skeletal maturity. The typical mechanism of injury involves forceful external rotation of the ankle occurring during a fall or a twisting injury occurring during ambulation.
A triplane fracture is a fracture of the distal tibia with fracture components in the following anatomical planes: sagittal, coronal (frontal), and axial (transverse). The fracture may or may not have combinations of Salter-Harris types II, III, and IV patterns. In 50% of the cases, the fibula is fractured as well.1 When the fracture is along the coronal plane of the tibia, it involves the posterior tibial metaphysis and a portion of the epiphysis.1 When the fracture is in the sagittal plane, the fracture line occurs through the epiphysis and is vertical in orientation. The fracture line typically starts at the midportion of the plafond (the horizontal surface of the tibia that articulates with the talus), but it may start anywhere along the anterior border of the epiphysis and extend in various directions along the tibia. When the fracture is in the axial plane, it can involve the articular cartilage, epiphysis, physis, and metaphysis. When axial components of the fracture are present, they portend a higher risk of complications if the physis prematurely closes.
Diagnosis can be made with radiographs; however, they do not consistently demonstrate the number of fracture fragments or the fracture itself. However, if radiography is the only imaging modality available, all radiographic views must be closely examined to visualize all the fracture lines. The sagittal fracture components are best visualized in the mortise view radiograph, while the coronal fracture components can be seen best on lateral radiographs.1 Axial component fractures are sometimes difficult to visualize because they occur through the physis and may require two- or three-dimensional imagining (such as computed tomography).
More recently, CT is recommended for triplane fractures, especially if they are not well-visualized on the radiograph (or if the radiographic finding is questionable for this type of fracture).1 CT scans can show the configuration of the fracture and aid in evaluation of articular displacement and in preoperative planning if the fracture requires open reduction and internal fixation (ORIF). If ORIF is necessary, CT offers signifi cant improvements in accuracy for plans on screw insertion and direction of screw placement compared with preoperative plans made using plain radiographs.2
Closed treatment is appropriate for nondisplaced triplane (less than 2 mm of displacement) and extra-articular fractures. The leg is immobilized with a long leg cast, and serial radiographs are performed to assess healing. In contrast, in fractures where articular surface displacement is greater than 2 mm, ORIF is often required.1,3 Following ORIF, the leg is placed in a nonweight-bearing long leg cast for 3 to 4 weeks, followed by a short leg cast. When treated appropriately, most patients have excellent outcomes and return to preactivity levels without complications. If treated inappropriately, growth arrest and significant tibiotalar joint pathology can result. Our patient was a skeletally immature boy who sustained an injury that could commonly suggest a typical ankle strain. Although the initial injury radiographs may appear grossly unremarkable to the casual observer, closer inspection may reveal more signifi cant injuries. In such instances, CT is warranted to complete the workup and treatment. JAAPA
Denise Rizzolo is a physician assistant at the Care Station in Springfi eld, New Jersey, and a clinical assistant professor, Pace University-Lenox Hill Hospital Physician Assistant Program, New York, New York. William Min is Chief Resident, Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, New York, New York. The authors have indicated no relationships to disclose relating to the content of this article.
REFERENCES
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