Bilateral Distal Tibial Transitional Ankle Fractures

n radiologic case study Enhance your diagnostic skills with this “test yourself” monthly column, which features a radiograph and challenges you to make a diagnosis.

The case: A

13-year-old boy presented to the emergency department with bilateral ankle pain and swelling following a 5-foot fall from a swing set.

Figure: Coronal (A) and sagittal (B) computed tomography scans of the right ankle.

Your diagnosis?

For answer see page 853

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n radiologic case study Section Editors: Terrence C. Demos, MD & Laurie M. Lomasney, MD

Diagnosis:

Bilateral Distal Tibial Transitional Ankle Fractures Andrew J. Rosenbaum, MD; Mostafa Abousayed, MB, BCH; Cory M. Czajka, MD; John A. DiPreta, MD; Richard Alfred, MD; Richard L. Uhl, MD

Answer to Radiologic Case Study Case facts appear on page 795

A

n otherwise healthy 13-year-old boy was brought to the emergency department after a 5-foot fall from a swing set. He reported bilateral ankle pain and had diffuse swelling and tenderness to palpation noted on examination. Plain radiographs of the ankles were obtained, identifying bilateral distal tibial epiphyseal injuries. To better delineate the fracture patterns, computed tomography (CT) scans of the ankles were obtained, demonstrating a right-sided triplane fracture (Figure 1) and a left-sided Tillaux fracture (Figure 2). Closed reduction was attempt-

ed but was unsuccessful. As such, open reduction and internal fixation was performed on both ankles. At 1-year follow-up, the patient was doing well, with no activity limitations, residual pain, or evidence of growth arrest (Figure 3).

Figure 1: Coronal (A) and sagittal (B) computed tomography scans of the right ankle, consistent with a triplane fracture. The coronal cut demonstrates a Salter-Harris III injury, while the sagittal view depicts a Salter-Harris II injury.

Etiology Closure of the distal tibial physis occurs over an 18-month period. It begins centrally and then proceeds anteromedially, posteromedially, and to the lateral aspect of the epiphysis.1 During this time, children are susceptible to transitional ankle injuries.

The authors are from the Division of Orthopaedic Surgery, Albany Medical Center, Albany, New York. The authors have no relevant financial relationships to disclose. Correspondence should be addressed to: Andrew J. Rosenbaum, MD, 1367 Washington Ave, Ste 202, Albany, NY 12206 (andrewjrosenbaum@ gmail.com). doi: 10.3928/01477447-20141124-01

Figure 2: Coronal (A) and sagittal (B) computed tomography scans of the left ankle, consistent with a Tillaux fracture. Both the coronal cut and the sagittal cut demonstrate Salter-Harris III injuries.

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Figure 3: Anteroposterior (A) and lateral (B) radiographs obtained 12 months following open reduction and internal fixation of the left-sided Tillaux fracture. Anteroposterior (C) and lateral (D) radiographs obtained 12 months following open reduction and internal fixation of the right-sided triplane fracture.

Triplane fractures occur in children 12 to 15 years old as they progress toward skeletal maturity.2 The triplane fracture is usually attributed to an external rotation force of the foot on the leg, and behaves like a Salter-Harris IV injury. It consists of sagittal, transverse, and coronal components that traverse the physis, entering the ankle joint.3,4 Juvenile Tillaux fractures occur within a year of complete distal tibial physeal closure. At this time, only the anterolateral aspect of the physis is open. Like triplane fractures, Tillaux injuries are most often attributed to an external rotation force of the foot on the leg. However, the fracture pattern created in this setting most closely resembles a Salter-Harris III fracture.

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Most patients who sustain these injuries are adolescent males with right ankle involvement.5 This is attributed to the later closure of the lateral distal tibial physis in boys as compared with girls, making them more vulnerable to this injury for a greater amount of time.

Diagnosis Diagnostic imaging is an essential component of the workup of pediatric ankle injuries. Plain radiographs should be obtained first and should include anteroposterior (AP), lateral, and mortise views of the ankle.6 The triplane fracture appears as a Salter-Harris III fracture on AP radiographs and a SalterHarris II fracture on lateral radiographs. The juvenile Tillaux fracture appears as a

Salter-Harris III on both AP and lateral radiographs. When concern exists for a transitional ankle fracture, a CT scan must also be obtained to identify the true extent of the fracture and for potential preoperative planning.7,8 Horn et al9 compared CT scans with radiographs in the setting of Tillaux fractures and found that, although both modalities were accurate to within 1 mm 50% of the time, CT scans are more sensitive in detecting greater than 2 mm of fracture displacement, which is an indication for operative intervention. Additionally, a better understanding of fracture configuration, such as that provided by CT, correlates with improved outcomes following the treatment of transitional ankle fractures.10

Treatment Although closed reduction may be attempted first, poor outcomes have been observed with closed treatment of pediatric transitional ankle fractures when greater than 2 mm of displacement or greater than 2 mm of articular step-off are present.11,12 This is attributed to the energy of the injury and soft-tissue interposition at the fracture. Open reduction and internal fixation is therefore warranted in such instances (Figure 3). Lateral fractures are approached through an anterolateral incision, while open reduction of more medial fractures is performed through an anteromedial incision. Fixation is achieved with either Kirschner wires or cannulated screws.

Complications The development of posttraumatic arthritis is the primary concern with inadequately reduced transitional fractures of the distal tibial epiphysis. Premature physeal arrest, which is considered the most severe sequela of trans-physeal injuries, is unlikely in this setting because these fractures occur in patients close to skeletal maturity.13 The rate of premature growth arrest following triplane fractures has ranged from 0% to 21%. Tillaux fractures have even lower rates, as they occur in an older age group than triplane fractures.

Conclusion Triplane and Tillaux fractures represent a continuum of pediatric transitional ankle fractures that occur during closure of the distal tibial physis. Closure, which occurs over an 18-month period, begins centrally and then proceeds in an anteromedial direction, then posteromedial, and ultimately to the lateral aspect of the physis. Despite similar mechanisms of injury (an external rotation force of the foot on the leg), triplane and Tillaux fractures are separate entities, as the former present as SalterHarris IV injuries and the latter as Salter-Harris III fractures. Additionally, Tillaux fractures are traditionally seen in older children, occurring within a year of complete distal tibial physeal closure. This case illustrates the concept of asymmetric physeal closure, as the 13-year-old boy described sustained bilateral, simultaneous triplane and Tillaux fractures.

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Although the diagnostic workup and approach to treatment are similar, these fractures represent manifestations of distinct and different periods of skeletal growth. This is important to recognize because of the prognostic implications associated with these injuries.

References 1. Mac Nealy GA, Rogers LF, Hernandez R, Poznanski AK. Injuries of the distal tibial epiphysis: systematic radiographic evaluation. AJR Am J Roentgenol. 1982; 138:683689.

2. Kärrholm J. The triplane fracture: four years of follow-up of 21 cases and review of the literature. J Pediatr Orthop. 1997; 6:91-102. 3. Kling TF Jr. Operative treatment of ankle fractures in children. Orthop Clin North Am. 1990; 21:381-392. 4. Peiró A, Aracil J, Martos F, Mut T. Triplane distal tibial epiphyseal fracture. Clin Orthop Relat Res. 1981; 160:196-200. 5. Landin LA, Danielsson LG. Children’s ankle fractures: classification and epidemiology. Acta Orthop Scand. 1983; 54:634-640. 6. Blackburn EW, Aronsson DD, Rubright JH, Lisle JW. Ankle fractures in children. J Bone

Joint Surg Am. 2012; 94:12341244. 7. Jones S, Phillips N, Ali F, Fernandes JA, Flowers MJ, Smith TW. Triplane fractures of the distal tibia requiring open reduction and internal fixation: preoperative planning using computed tomography. Injury. 2003; 34:293-298.

10. Kim JR, Song KH, Song KJ, Lee HS. Treatment outcomes of triplane and Tillaux fractures of the ankle in adolescence. Clin Orthop Surg. 2010; 2:34-38. 11. Kay RM, Matthys GA. Pediatric ankle fractures: evaluation and treatment. J Am Acad Orthop Surg. 2001; 9:268-278.

8. Cutler L, Molloy A, Dhukuram V, Bass A. Do CT scans aid assessment of distal tibial physeal fractures? J Bone Joint Surg Br. 2004; 86:239-243.

12. Ertl JP, Barrack RL, Alexander AH, VanBuecken K. Triplane fracture of the distal tibial epiphysis: long-term follow-up. J Bone Joint Surg Am. 1988; 70:967-976.

9. Horn BD, Crisci K, Krug M, Pizzutillo PD, MacEwen GD. Radiographic evaluation of juvenile Tillaux fractures of the distal tibia. J Pediatr Orthop. 2001; 21:162-164.

13. Barmada A, Gaynor T, Mubarak SJ. Premature physeal closure following distal tibia physeal fractures: a new radiographic predictor. J Pediatr Orthop. 2003; 23:733-739.