A new type of triplane fracture in a 19-year-old snowboarder

Surgically Relevant Patterns in Triplane Fractures: A Mapping Study

BACKGROUND

Triplane ankle fractures are complex transitional fractures that often necessitate surgical treatment. Axial fracture lines determine optimal screw trajectories for fixation. The purpose of our study was to identify fracture patterns in triplane fractures by illustrating fracture lines in the axial plane of the distal tibial metaphysis and epiphysis.

METHODS

We retrospectively reviewed records of children presenting with ankle fractures at 1 center from January 2007 through June 2017. Thirty-three cases of triplane fractures with available computed tomographic (CT) scans were identified. Fractures in the axial plane of the metaphysis were identified 10 mm proximal to the physis, and fractures in the epiphysis were identified midway between the physis and distal tibial articular surface. Fracture lines were drawn and were superimposed on unfractured bone templates to generate fracture maps, and heat maps were then created to show areas of high and low fracture densities.

RESULTS

In the metaphysis, the most common fracture pattern was medial-lateral lines in the posterior metaphysis. This metaphyseal pattern was consistent across 2, 3, 4, and 5-part fractures. There were clear zones of rare fracture involvement in the anterior and anterolateral metaphysis. In the epiphysis, anterior-to-posterior fracture lines were common in the anterior epiphysis. All cases had an epiphyseal fracture exit through the anterior epiphysis. Fracture extension into the posteromedial epiphysis was a feature of all fracture classes.

CONCLUSIONS

Fracture mapping of triplane fractures suggests consistent axial fracture patterns in the metaphysis and epiphysis with additional class-dependent fractures in the epiphysis. This study provides visual guidelines to assist surgeons in understanding the axial fracture patterns of individual triplane fractures for surgical planning.

Pediatric physeal ankle fracture

Ankle fracture is the second most common fracture type in children, and physeal injury is a particular concern. Growing children have open physes that are relatively weak compared with surrounding bone and ligaments, and traumatic injuries can cause physeal damage and fracture. Tenderness to palpation over the physis can aid in the clinical diagnosis of ankle fracture. Swelling, bruising, and deformity may be identified, as well. Plain radiographs are excellent for initial evaluation, but CT may be required to determine displacement and to aid in surgical planning, particularly in the setting of intra-articular fractures. The Salter-Harris classification is the most widely used system to determine appropriate management and assess long-term prognosis. Complications of physeal injury include shortening and/or angular deformity. Tillaux and triplane fractures occur in the 18-month transitional period preceding physeal closure, which typically occurs at age 14 years in girls and age 16 years in boys. Management is determined by the amount of growth remaining, with the intent of maintaining optimum function while limiting the risk of physeal damage and joint incongruity.

The pediatric triplane ankle fracture

The pediatric triplane ankle fracture represents a unique spectrum of injury that does not fit neatly into the Salter-Harris classification of physeal injury. This fracture is particular to the pediatric population and often is termed a transitional injury. It is the result of the characteristic asymmetric closure of the distal tibial physis over a period of approximately 18 months. The triplane ankle fracture is a multiplanar injury with three classically described fracture fragments. It has several variations and represents 5% to 10% of pediatric intra-articular ankle injuries. The fracture typically presents in children aged 12 to 15 years; incidence is slightly higher in boys than in girls. Nondisplaced triplane fractures and extra-articular fractures can be managed with immobilization in a long leg cast. Displaced fractures are treated with open reduction and internal fixation performed through an anterolateral approach or an anteromedial approach. Intra-articular reduction to within 2 mm is required for optimal treatment of these unique pediatric ankle fractures.