We reported on case series of patients sustaining Tillaux fracture associated with MMF. This study showed that the mean AOFAS score of this complex fracture was 88.7, being comparable to the results reported in other series sustaining isolated fractures[5, 10].
In present series, most of the injury resulted from high-energy forces across the ankle joint. Even though the position of the foot immediately at the injury was uncertain, the external rotation forces be applied in all of the six cases and caused Tillaux fracture. When the force continued to be sufficient, the distal fibula will mostly appear a short oblique fracture and the posterior tibiofibular ligament was stretched to create the avulsion of PLTA, being similar to Volkmann fracture in adult. In addition, PLTA will also result from plantar flexion force. But this usually involves more displacement and a larger fragment. Extreme external rotation of the talus will create MMF in adolescence[7, 13]. In this series, four 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.
In general, the diagnosis of MMF and fibular fractures 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 with the plain radiographs. Horn et alcompared 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, however, identified on axial CT. We recommended that CT scanning 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 commonly significant edema of the soft tissue following high-energy injury and the wound infection and necrosis rates up to 33%. Miller et al]17]recommended that surgery be delayed to seven to 14 days until the soft-tissue edema has decreased. Meanwhile, strategy of staged treatment for severe ankle injury has been reported in good to excellent outcomes in adults. This may be a dilemma for pediatric ankle fractures due to open physis. Although Crawford 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, 10]. In our series, surgery were underwent in five cases 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.
Hanhisuanto et alrecommended that more than 2 mm displaced fractures be treated operatively for MMF. In our series, the initial displacement for Tillaux fracture was more greater(2-9.4 mm) than 2 mm 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[19,21]. Our study showed that four cases obtained bony union with closed reduction and K-wire and one nonunion because of no reduction or technique error. Hence, we found that it is of significant importance to fix MMF.
In five distal fibular fractures, three patients with TS were immobilized with plate and screws to restore and maintain the mortise. The widening of medial joint space and TS were reduced to normal in two cases with reduction of the fractures. SD was detected in one case on preoperative axial CT and persistent diastasis was confirmed postoperatively(Fig. 3). This may be the result of Tillaux fracture and MMF being not reduced and fixed.
There were rare reports with respect to the avulsion of PLTA in adolescence. 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[13,22]. Von Hooff et al found when the posterior malleolar fracture fragments was more than 5% and the step-off more 1 mm, osteoarthritis occurred more frequently. Donken et al reported a good long-term clinical and radiological result treated conservatively with closed reduction and cast. In present series, we found no displacement and no fixation was undergone for both cases.
One study of intra-articular physeal injury of the ankle by Caterini et al, with an average follow-up of 27 year, showed radiographic osteoarthritis signs in 11.8%. They found that the initial displacement and the quality of reduction were the main risk factors that determined the results. In our study, one child developed posttraumatic osteoarthritis due to the malreduction of Tillaux fracture and instability of the ankle. Furthermore, this case suffered from falling that may cause significant cartilage damage.
In conclusion, simultaneous Tillaux fracture and MMF in adolescences 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.