Pincer or split fractures are coronally oriented vertebral body fractures that involve the superior and inferior vertebral body endplates but do not involve the anterior or posterior cortices.
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Clinical Presentation
Pincer fractures may present in the setting of trauma, with an axial loading mechanism of injury through the thoracolumbar spine. Additionally, an atraumatic or minimally-traumatic presentation can occur in the cases of osteoporotic insufficiency fractures.
Terminology
Although described in alternative classification systems, the terminology of pincer or split fracture is most commonly used to describe this type of fracture.
Epidemiology
One retrospective study found in a population of 101 patients who underwent surgical stabilization of a thoracolumbar injury, a pincer fracture was observed in 14 of the cases (incidence 13.9%) 1.
Pathology
Pincer fractures are most common in the thoracolumbar spine. They can occur in cases of osteoporotic insufficiency fractures and axial loading/traumatic injuries.
Associated disc tears can occur which can result in the disc filling the endplate fracture defect causing further dislocation of the anterior fracture segment and increasing the risk of fracture non-union or pseudoarthrosis1 .
Classification
Pincer or split fractures are alternatively named in other classification systems including the AO spine classification of thoracolumbar injuries under which a pincer fracture is classed as an A2 2.
Using the AO Spine German Society for Orthopedics and Trauma (DGOU) Osteoporotic Fracture (OF) Classification System a pincer fracture would be classed as OF4.
Radiographic Features
Plain radiographs, CT and MRI show a fracture line extending from the superior to the inferior cortices of the affected vertebral body. The anterior and posterior vertebral body cortices are not involved. This gives the pincer fracture its distinctive appearance on sagittal imaging.
There is often communition of the medial vertebral body associated with this fracture 1. Additionally, the anterior fragment of the vertebral body is at risk of anterior dislocation.
Differential Diagnoses
- other thoracolumbar vertebral body fracture as described by the AO spine classification of thoracolumbar injuries
- burst fracture
- wedge fracture