Anatomy
Summary
Spondylolysis is a fracture of the pars interarticularis, often identified by the pathognomonic Scotty dog sign on imaging. This condition is common in young athletes like dancers or gymnasts who engage in repetitive hyperextension of the spine. Spondylolisthesis may occur following spondylosis, characterized by the anterior sliding of a vertebral body. In the cervical region, fractures of the C1 vertebra (atlas), can result from direct vertex injuries like diving. A specific type of C1 fracture involving all four arches is called a Jefferson burst fracture.
C2 (axis), may sustain an isolated fracture known as a hangman's fracture, common in hanging injuries. Another type of C2 injury, a dens fracture, results from horizontal blows to the head and can lead to avascular necrosis of the dens. Whiplash injuries are a result of severe hyperextension and hyperflexion, often causing injury to interspinous ligaments and tearing of the anterior longitudinal ligament. Severe hyperflexion injuries can result in 'jumped' and 'locking' facets as well as a 'tear drop' fracture of the anteroinferior part of the vertebral body.
Lesson Outline
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FAQs
Severe hyperextension and hyperflexion of the spine are commonly seen in whiplash injuries. These movements can result in a range of spinal injuries including tearing of the anterior longitudinal ligament, and damage to the interspinous ligaments (hyperflexion). Additionally, fractures like the 'tear drop' fracture of the vertebral body can occur with hyperflexion (most common) and hyperextension injuries.
Young athletes like dancers and gymnasts are more susceptible to spondylolysis due to the repetitive hyperextension of the spines during those activities. These movements place significant stress on the pars interarticularis, leading to a higher risk for developing stress fractures in this area, known as spondylolysis.
Spondylolysis refers to a stress fracture in the pars interarticularis, while spondylolisthesis occurs when the fractured vertebra slides anteriorly over the vertebra below it. Spondylolysis is often a precursor to spondylolisthesis, especially if the stress fracture is not adequately managed or treated.
A Jefferson burst fracture is a specific type of C1 (atlas) fracture that occurs when all four arches of the C1 vertebra are fractured. This injury is typically due to direct axial forces, such as those experienced in diving accidents. It is a highly unstable fracture that requires immediate intervention.
The significance of a Scotty dog sign lies in its diagnostic utility for spondylolysis. This radiographic sign is pathognomonic for the condition, where the "collar" of the Scotty dog represents the fracture line in the pars interarticularis. It is a reliable tool for clinicians to identify the presence of spondylolysis in spinal imaging.
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