A 14-year-old previously healthy girl is evaluated for a 3-month history of low back pain. She is a member of her school gymnastics team, and the pain is worse after training sessions. The patient reports no significant back trauma and has had no weakness or numbness in the lower extremities. Menarche was at age 9 and she has had regular menstruations. Vital signs are within normal limits. Physical examination shows tenderness in the L5 region, but no neurologic deficits are present. A spine x-ray reveals anterior displacement of L5 vertebra relative to the S1 vertebra. This patient's condition is most likely caused by injury to which of the following structures?

Question

A 14-year-old previously healthy girl is evaluated for a 3-month history of low back pain.  She is a member of her school gymnastics team, and the pain is worse after training sessions.  The patient reports no significant back trauma and has had no weakness or numbness in the lower extremities.  Menarche was at age 9 and she has had regular menstruations.  Vital signs are within normal limits.  Physical examination shows tenderness in the L5 region, but no neurologic deficits are present.  A spine x-ray reveals anterior displacement of L5 vertebra relative to the S1 vertebra.  This patient's condition is most likely caused by injury to which of the following structures?

Quizplus · Accepted Answer

11ec160b_35f3_9644_9249_014353470af0_MD0001_00 This adolescent athlete has spondylolisthesis (ie, anterior displacement of the vertebral body), which often occurs due to bilateral spondylolysis (ie, pars interarticularis fracture). The vertebral column is formed by stacked vertebra separated by cartilaginous discs held together by thick ligaments: The vertebral bodies form the anterior, weight-bearing portion of the vertebral column. The posterior portion of the vertebral column contains the midline spinous process, the transverse processes, and the articulating processes of the facet joints. The posterior vertebral arch connects the anterior and posterior portions of the vertebral column and consists of the pedicle, the intervening pars interarticularis, and the lamina. The posterior vertebral arch and the posterior portion of the vertebral body form the triangularly shaped spinal canal. Each vertebra has an anterior joint between the vertebral bodies separated by discs and a pair of facet joints posteriorly. Forward flexion of the spine stresses the anterior portion of the spine, including the vertebral bodies and discs; repetitive extension of the spine (as in gymnasts) stresses the facet joints and posterior vertebral arch, which can lead to spondylolysis with subsequent spondylolisthesis. (Choice A) The intervertebral disc is a shock-absorbing cartilaginous structure between the vertebral bodies made of a tough cartilage ring (ie, anulus fibrosis) surrounding a soft fibrocartilaginous core (ie, nucleus pulposus). Damage can lead to herniation of the disc or loss of space between the vertebral bodies but would not cause anterior displacement of the vertebral bodies. (Choices C and D) The spinous process projects posteriorly in the midline and serves as an attachment of muscles and ligaments. The paired transverse processes project posterolaterally from the vertebral arch. In the thoracic vertebrae, facets on the transverse processes articulate with the tubercles of the ribs. Fractures of the spinous process or transverse processes are considered stable; they do not typically result in either neurologic compromise or displacement of the vertebral bodies. (Choice E) The vertebral body is the weight-bearing, anterior portion of the vertebrae. Fractures to this area may cause avulsions or compression fractures that lead to a loss of height but not typically to displacement. Educational objective: Fracture of the posterior vertebral arch often occurs at the pars interarticularis (ie, spondylolysis). Bilateral disruption of the pars interarticularis can lead to anterior displacement of the vertebral body (ie, spondylolisthesis).

A 14-Year-Old Previously Healthy Girl Is Evaluated for a 3-Month