Pars interarticularis marked with red lines Diagnosis A significant number of individuals with spondylolysis will develop spondylolisthesis, which is true for 50-81% of this population. This stress fracture most commonly occurs where the concave lumbar spine transitions to the convex sacrum (L5-S1). The pars interarticularis is vulnerable to fracture during spinal hyperextension, especially when combined with rotation, or when experiencing a force during a landing. Spondylolysis is typically caused by a stress fracture of the bone, and is especially common in adolescents who over-train in activities. Separation of the pars interarticularis occurs when spondylolysis is present in the spinal column. When examining the vertebra, the pars interarticularis is the bony segment between the superior and inferior articular facet joints located anterior to the lamina and posterior to the pedicle. The lumbar vertebra consist of a body, pedicle, lamina, pars interarticularis, transverse process, spinous process and superior and inferior articular facets, which form joints that link the vertebrae together. The vast majority of spondylolysis occur in the lumbar vertebrae, however it can also be seen in cervical vertebrae. Spondylolysis is a bony defect or fracture within the pars interarticularis of the vertebral arch in the spinal column. Spondylolysis also runs in families suggesting a hereditary component such as a predisposition to weaker vertebrae. In one study looking at youth athletes, it was found that the mean age of individuals with spondylolysis was 20 years of age. Males are more commonly affected by spondylolysis than females. Ultimate Frisbee (especially during impact from laying out)Īlthough this condition can be caused by repetitive trauma to the lumbar spine in strenuous sports, other risk factors can also predispose individuals to spondylolysis.Spondylolysis has a higher occurrence in the following activities: For instance, for a right-handed player, the fracture occurs on the left side of the vertebrae. The stress fracture of the pars interarticularis occurs on the side opposite to activity. Sports involving repetitive or forceful hyperextension of the spine, especially when combined with rotation are the main mechanism of injury for spondylolysis. It is believed that both repetitive trauma and an inherent genetic weakness can make an individual more susceptible to spondylolysis. Spondylolysis is a common cause of low back pain in preadolescents and adolescent athletes, as it accounts for about 50% of all low back pain. This leaves young athletes at increased risk, particularly when involved in repetitive hyperextension and rotation across the lumbar spine. In a young athlete, the spine is still growing there are many ossification centers, leaving points of weakness in the spine. The disorder is generally more prevalent in males than in females and tends to occur earlier in males due to their involvement in more strenuous activities at a younger age. Research supports that there are hereditary and acquired risk factors that can make one more susceptible to the defect. The condition is present in up to 6% of the population, the majority of which usually present asymptomatically. The cause of spondylolysis remains unknown, however many factors are thought to contribute to its development. Pain aggravated with lumbar hyperextension.Pain that worsens after strenuous activity.Pain that can restrict daily activities.Pain that radiates into the buttocks or legs.Visible on diagnostic imaging (Scottie dog fracture ).Pain on completion of the stork test (placed in hyperextension and rotation).When a patient does present with symptoms, there are general signs and symptoms a clinician will look for: In majority of cases, spondylolysis presents asymptomatically, which can make diagnosis both difficult and incidental. The vast majority of cases occur in the lower lumbar vertebrae (L5), but spondylolysis may also occur in the cervical vertebrae. Spondylolysis is a defect or stress fracture in the pars interarticularis of the vertebral arch. Spondylolysis (wrong descriptions: the upper 3 arrows should be partes interarticulares)

Bilateral pars defect