Accessory ossification centers occur in both the malleoli. In some cases, this ossification center fails to fuse with the epiphysis, and an accessory ossicle develops. Fracture of the synchrondrosis between the ossicle and the malleolus may occur and cause pain. The tenderness is exactly localized over the tip of the malleolus. This unique localization is often diagnostic.
Os subfibulare This ossicle of the lateral malleolus may be trauma-tically separated and painful. Manage acute separation as a fracture. Immobilize in a short-leg cast for 4 weeks. Rarely, healing fails and excision or grafting of the painful ossicle may be required.
Ankle sprains become increasingly common with advancing age. Sprains are common in adolescents. Lateral sprains that involve the calcaneocuboid ligament and lateral collateral ligaments are most common. The site of sprain can usually be determined by the PMT. If bone tenderness is found or clinical findings are atypical, make AP, oblique, and lateral radiographs.
Mild sprains Sprains of the anterior talofibular and calcanocuboid ligament are managed with an elastic bandage, elevation, and cold application. Limit activity until tenderness is no longer present.
Moderate to severe sprains Manage in a short-leg walking cast for 4 weeks.
Recurrent sprains Order stress radiographs to assess stability. Unstable and symptomatic ankles may require repair as in adults.
Ankle fractures in children are varied and complex. These fractures result from a complex interplay of the mechanism of injury and the changing physiology of the immature ankle.
Age Fracture patterns change with age.
Early childhood During infancy, the weakest part of the bone is the metaphysis. These injuries may spare the physis and ligaments.
Middle to late childhood Later in childhood, the physis becomes relative weaker, and failure may occur at that level. Disruption of the distal fibular epiphysis may be difficult to diagnose.
Adolescence Complex fracture patterns in teens are due to asymmetrical closure of the physis. Such fractures are often categorized as transitional. Tears of the collateral ligaments become more common.
Inversion and eversion fractures Lateral failure may occur through the ligaments, the epiphysis, or the physis. Often the physis fails. This may be difficult to recognize by examination or conventional imaging. MRI studies of ankles demonstrate physeal failure to be quite common. Manage these injuries by immobilization in a short-leg cast for 4 weeks.
Plantar–flexion fracture Failure may occur in the tibia or growth plate.
Tibial physeal fracture Evaluate by AP, lateral, and both oblique radiographs. If the extent of displacement is uncertain, CT evaluation may be necessary. Displacement of >2 mm requires reduction. Fix with metalic or absorbable fixation devices. Supplement fixation in a long-leg cast for 4 weeks.
Triplane fractures These are transitional fractures of the distal tibia. Fracture patterns at the end of growth are based on relative strength of the bone and physis and also on the sequence of closure of the physis. They are classified as medial or lateral types. Each type has subtypes with two, three, four, or more fragments. Numerous classification schemes have been devised because the patterns are so diverse as to defy easy categorization.
Evaluation Study AP, mortise, and lateral radiographs. If the pattern is unclear, order a CT scan. Often the CT scan shows more displacement than conventional radiographs. If still uncertain, a three-dimensional reconstruction may be necessary. Whenever possible, try to understand the fracture pattern and plan the reduction before undertaking the procedure.
Management The major objective is to restore the articular surfaces to prevent degenerative arthritis. Apply the 2-mm rule. Vertical displacement is more significant than simple horizontal separation of the fragments. Following reduction, fix with screws (see next page) and immobilize in a long-leg cast for 4 weeks.
Tillaux fracture This fracture pattern results from asymmetrical closure of the distal tibial epiphysis because the anterolateral aspect of the growth plate may remain open when the remainder is fused. Avulsion of this unfused portion of the epiphysis produces this unique fracture. CT imaging may be useful to evaluate the true displacement of this fracture. Most require operative fixation.
Ankle Fracture Reduction and Fixation
Manage undisplaced fractures in a cast for 6 weeks. Apply a long-leg cast with the knee flexed about 30 degrees. Repeat radiographs in the cast at 1 and 2 weeks to confirm maintenance of reduction. Continue the immobilization for a total of 6 weeks.
Metaphyseal and SH-1 and SH-2 Fractures
These ankle fractures do not require anatomic reduction. The amount of acceptable displacement depends on the age. Varus or valgus deformity in the older child should be corrected, as remodeling may be incomplete. Internal fixation is sometimes necessary.
Displaced SH-3 and SH-4 Fractures
Displaced fractures that exceed 2 mm of displacement require reduction. Assess degree of displacement with supplemental oblique or CT radiographs if degree of displacement is uncertain. Attempt a closed reduction under anesthesia. Reduce by reversing the direction of the injury. If reduction is not satisfactory, perform an open reduction. Establish the pattern of deformity before undertaking the procedure. Arrange intraoperative imaging. Make the approach based on the fracture pattern. Do not hesitate to make two incisions to aid visualization and fixation. Fix with metallic or absorbable pins or screws. Limited internal fixation is adequate, as fixation is supplemented by a long-leg cast.
Medial malleolus fracture is a SH-3, SH-4, or rarely a SH-5 injury. Growth arrest and deformity are common sequelae. Consider placing a prophylactic fat graft to fill any residual defect that spans the growth plate. aFix with a horizontal screw that remains within the epiphysis, or with small, smooth K wires, which may transverse the physis and can be removed.
Tillaux fractures are SH-3 anterolateral epiphyseal fractures. Expose the fracture through an anterolateral approach, reduce by internal rotation of the foot. Usually, the growth plate is closing, so growth disturbance is seldom a problem.
Triplane fractures are SH-4 injuries that include a variety of fracture patterns, which are often complex. Medial triplane fractures often include two or three fragments. Fracture patterns are varied and include many patterns, requiring tailoring the approach and fixation based on the situation. Reduction can sometimes be difficult. Approach through two incisions, if necessary. Fix with horizontal screws.