Dias and Tachdjian modified the Lauge-Hansen classification system for ankle fractures in adults and first described pediatric ankle fractures with respect to the foot position and indirect force applied to the ankle[10]. This classification is compromised of four basic fracture patterns: supination and inversion, pronation or eversion external rotation, supination and plantar flexion, and supination and external rotation. However, the Dias-Tachdjian classification does not cover all fracture types cross the ankle in adolescents. The fracture presented in our patients was rare fracture type which has not been reported in previous articles. Even though the position of the foot immediately at the injury was uncertain, we believed that the external rotational force be applied in all of the six cases and caused Tillaux fracture. As the external rotation force was sufficient, the fracture of distal fibula and APITEL will occur. Extreme external rotation of the talus may shift the talus, disrupt the medial restraint and create MMF in adolescents[7,11]. In this series, five MMF lines lied adjacent and parallel to the level of distal tibial plafond. This may be the result of the impingement between the talus and the medial malleolus[12].
The diagnosis of MMF may be easily detected on plain radiographs. Tillaux and PLTA fracture, however, will be missed due to the superimposition of the fibula. Furthermore, as an intraarticular fracture of Tillaux fracture, it may be difficult to evaluate the actual amount of the displacement and the direction by plain radiography. Horn et a[13]compared the accuracy of CT and plain radiographs in evaluation of juvenile Tillaux fractures in cadaver specimens. They concluded that CT was more sensitive than plain radiographs in detecting fractures with more than 2 mm of displacement. Moreover, CT can reveal the true dimensions and displacement of these fragments. In present study, the diagnosis of Tillaux fracture in one and both of the avulsion of PLTA were missed in plain radiographs, and were identified on axial CT. We recommended that CT will be extremely paramount to demonstrate the fracture clearly and be helpful to make decision in treatment for cases of high-energy ankle injury.
There was significant edema of the soft tissue following high-energy injury and it was essential to treat soft-tissue injury for good outcomes. Miller et al[14]recommended that surgery be delayed to seven to 14 days until the soft-tissue edema has decreased. The strategy of staged treatment for severe ankle injury has been reported in good to excellent outcomes in adults. However, This may be a dilemma for pediatric ankle fractures due to the open physis. Although Crawford[15] noted that Tillaux fracture could be reduced 5 weeks later, reduction for physeal fractures was recommended generally not to be performed after five to seven days to minimize the PPC[3,16]. In our cases, surgery in five cases was underwent with three to seven days between the injury and operation. Significant swelling was encountered in one case and the surgery was delayed until 3 weeks resulting in nonunion of MMF and Tillaux fracture.
For Tillaux fracture, most reports recommended anatomical reduction and internal fixation to minimize the bone bridge and PPC in case of more than 2mm displacement. In our series, the initial displacement for Tillaux fracture was more greater(2-9.4mm) than 2mm due to the high-energy force, and all cases exception one were performed by open reduction and K-wires fixation. The result was comparable with the fixation of screws[15,16].
With regarding to the H-type B and C fractures in adult, a study with 35 case series treated conservatively demonstrated a high rate of union and good functional results and two cases of nonunion occurred in type C fracture[6]. On the other hand, Hanhisuanto et al[17]recommended that more than 2mm displaced fractures be treated operatively. Our study showed that two nonunion because of no internal fixation. Many factors were related with the bone healing[18,19]. Our results suggest that internal fixation is more effective for MMF in adolescents.
Gourineni and Gupta [7] believed that the Tillaux fragment, talus and the lateral malleolus moved laterally together as one unit in Tillaux fracture. They emphasized that widening of medial joint space will be restored to normal after reduction of the Tillaux fragment. In our study, three patients with TS were immobilized with plate and screws in order to restore and maintain the mortise. The widening of medial joint space and TS were reduced in two cases. But SD was detected in one case on preoperative axial CT and persistent diastasis was confirmed postoperatively. This may be the result of Tillaux fracture and MMF being not reduced and fixed.
There were rare reports with respect to the APITEL in adolescents. In adult, treatment of posterior malleolus is determined by several factors, such as the size of fragment, the fracture gap, and the step-off of the joint surface[11,20]. Donken et al[21] reported a good long-term clinical and radiological result treated conservatively with closed reduction and cast. In present cases, we found no displacement and no fixation was undergone for both cases.
In conclusion, simultaneous Tillaux fracture and MMF in adolescents is rare and has not been previously reported. Diagnosis at the initial admission using plain radiographs are challenging, and CT is recommended. It is the recommendation of this study that ORIF can be efficacious for joint congruity. Our study is limited by small group and relative shorter following-up.