- most common type of pediatric ankle fracture;
- involves adduction injury to a supinated foot;
- Classification:
- type I: (involves fibula);
- separation of distal fibular epiphysis (SH I or II frx);
- epiphyseal separation involves distal fibula & is due to inversion force;
- may be confused w/ ankle sprain;
- palpation of fibular physis will elicit tenderness;
- key to dx is soft tissue swelling on x-rays, located over distal fibular epiphysis;
- look for slight medial displacement;
- look for widening of the physis on oblique views;
- comparison views of the opposite ankle is helpful;
- treatment: short leg cast for 3-4 weeks;
- complications:
- shortening of fibula, with lateral shifting of talus;
- resulting laterally increased pressure on tibia causes some growth inhibition & resulting valgus deformity of ankle;
- type II Frx: (additional injury to distal tibia);
- Complications: Varus Deformity:
- due to asymmetric arrest of distal medial tibial growth plate:
- most common angular deformity seen in this injury;
- osseous bridge in medial part of physeal plate may develop after a Salter Harris III or IV injury;
- if the growth plate is damaged at the time of injury, even an undisplaced frx can develop a varus deformity;
- radiographs:
- Harris growth arrest lines are seen to converge over the physis at the point of injury;
- damaged physis may appear radiodense;
- tomograms help define the bone bridge;
- prevention:
- anatomical reduction of the fracture may reduce the incidence of varus growth deformity;
- in late cases, consider physeal bar resection or opening wedge supra-malleolar osteotomy;
- Case Example:
- 12-year-old male who sustain a left supination inversion frx, which was treated w/ percutaneous pinning;
- key points:
- the medial pin was incorrectly placed across the physis as opposed to parallel to it;
- a non anatomic reduction was accepted, which may have led to growth plate arrest;
- this patient would have been better served w/ an open reduction;
right ankle left ankle
Supination-adduction injuries of the ankle in children--radiographical classification and treatment.