Figure 1. Anteroposterior radiograph of the left ankle.
Figure 2. Lateral view of the ankle.
A 15-year-old adolescent presents with left ankle pain after twisting his ankle on a hike in the woods a day earlier. He has had difficulty with weight-bearing on the ankle since the injury. On physical examination, the patient has mild swelling over the medial ankle and pain to palpation of the medial and lateral malleoli. Radiographs of the ankle are taken (Figures 1 and 2).
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The patient has a Salter-Harris type IV fracture of the medial malleolus. The fracture extends from the epiphysis through the physis and includes a small metaphyseal fragment. The fracture was found to be displaced 5 mm on computed tomography (CT) scan, which is well beyond the acceptable 2 mm of displacement (nondisplaced) allowed for conservative treatment.1 Articular step-off greater than 2 mm (displaced) is associated with an increased risk of post-traumatic arthritis.1
Computed tomography imaging is recommended for all patients suspected of having an articular step-off. This imaging can often change the course of treatment by determining fracture pattern and displacement, which can be difficult to view on plain radiograph.1,2 This patient is approaching skeletal majority; the distal tibial physis usually closes by age 16 years in males.1 Because of this, screw fixation from the medial malleolus through the physis can be performed without fear of causing growth arrest.1,2
This patient’s surgery required an open reduction because his thick periosteum blocked attempts at closed reduction.
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopedics for Physician Assistants.
1. Ahn L, Souder C, Herman M. Ankle fractures — pediatric. Ortho Bullets. Updated August 24, 2021. Accessed on August 2, 2022. https://www.orthobullets.com/pediatrics/4027/ankle-fractures–pediatric
2. Su AW, Larson AN. Pediatric ankle fractures: concepts and treatment principles. Foot Ankle Clin. 2015;20(4):705-719. doi:10.1016/j.fcl.2015.07.004