Coronal computed tomography of a 13-year-old boy who injured his knee jumping off of a wall shows a minimally displaced Salter-Harris type II distal femur fracture at the medial metaphysis with slight widening of the posterior lateral growth plate.
Initial anteroposterior x-ray of the patient showed a possible distal femur physeal fracture.
A 13-year old boy presents 1 week after sustaining a right knee injury when he jumped off a wall and landed awkwardly. He was seen in the emergency department after the injury and initial radiographs showed a possible distal femur physeal fracture. Computed tomography is performed and shows a minimally displaced Salter-Harris type II distal femur fracture at the medial metaphysis, with slight widening of the posterior lateral growth plate.
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Distal femoral physeal fractures are particularly prone to growth disturbances, including partial or complete premature growth arrest. The distal femoral physis contributes to 40% of lower extremity growth and therefore, growth arrest can cause significant deformity and leg length discrepancy.
The patient in this case presents with a minimally displaced Salter-Harris type II fracture characterized by an oblique metaphyseal fracture line that stops at the physis. The metaphyseal corner that remains attached to the physis is called the Thurstan-Holland fragment, and it varies in size. The physis under the Thurstan-Holland fragment is usually spared from injury, and growth arrest is more likely to occur on the contralateral side of the physis. This metaphyseal fracture occurred medially and therefore, the patient is at risk for valgus deformity should growth arrest occur.1
Nondisplaced distal femoral physeal fractures and fractures with <2 mm of displacement can be treated with a well-molded long leg cast. The risk for growth arrest for Salter-Harris type II fractures is significant, and close follow-up with serial radiographs is necessary. Leg length discrepancy or angular deformity as a result of physeal disturbances can occur in 30% to 60% of those with Salter-Harris type II fractures. The implications of physeal arrest are largely dependent on age and remaining growth left at the time of injury. Patients with significant growth potential remaining are more likely to have a significant deformity. Follow-up radiographs should be taken at 12 to 24 months to ensure that no growth arrest has occurred.1,2
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 (JOPA).
- Souder C. Distal Femoral Physeal Fractures—Pediatric. Orthobullets website. http://www.orthobullets.com/pediatrics/4020/distal-femoral-physeal-fractures–pediatric. Accessed January 17, 2017.
- Skaggs DL. Extra-articular injuries of the knee. In: Beaty JH, Kasser JR, eds. Rockwood and Wilkins’ Fractures in Children. 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2006.