Spondylolisthesis

A 16-year-old boy presents to the clinic for evaluation of low back pain. The patient is participating in gymnastics training and has had difficulty preparing for an upcoming competition due to persistent low back pain that is worse with movement and relieved with rest. The patient is otherwise healthy. He has not had any recent injury or trauma. Vital signs are within normal limits. On physical examination, the low back is noted to be hyperlordotic. Pain is elicited with passive extension of the back. The straight leg test is negative bilaterally. A radiograph of the lumbar spine is shown below. Which of the following best describes the etiology of this patient’s clinical presentation?  


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