Physeal fractures (also called Salter-Harris fractures) are important childhood fractures that involve the physis (physeal/growth plate). They are relatively common and important to differentiate from other injuries because the involvement of the physis may cause premature closure resulting in limb shortening and abnormal growth.
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Terminology
Physeal fractures are also commonly called Salter-Harris fractures because the dominant and ubiquitous classification for these injuries is the Salter-Harris classification.
Epidemiology
Physeal fractures represent ~35% of all skeletal injuries in children 2.
Clinical presentation
Physeal fractures are most common in 10-to-16-year-old children, except for elbow fractures, which are more common in 3-to-6-year-old children 2. They most commonly occur following trauma, although at the hip, a slipped upper femoral epiphysis (SUFE) is a type I fracture that can occur without an acute traumatic event.
Pathology
The growth plate has five distinctive zones. Fractures tend to propagate along the weakest zone, which is the spongiosum. Fortunately, this is not a region of active growth, and therefore fractures through this area have a good prognosis. When the fracture passes towards the epiphysis, it passes through the zones of proliferation and reserve which result in possible premature closure of the growth plate at the fracture site.
Radiographic features
Plain radiograph
X-rays are usually all that is required to make the diagnosis. If the fracture is completely within the physis, there is no bony abnormality and there may just be widening or narrowing of the physis which can be challenging to diagnose at the initial presentation.
CT
Complex metaphyseal or epiphyseal fractures can be further assessed at CT.
MRI
MRI is useful for the assessment of a suspected physeal injury and may identify bone edema adjacent to the injured physis:
- T1/PD: assessment of physis orientation
- STIR/PDFS: bone edema
- DESS: thin-section volume imaging of the physis
