A 17-year-old girl is brought to the office by her parents due to progressive back pain. The pain, which is in the central lower back, began several weeks ago during ballet practice. Over the last 2 weeks, it has worsened. She has been using acetaminophen and ibuprofen with minimal improvement. The patient has had no fever, chills, weakness or numbness in the legs, or recent illnesses. Medical history is unremarkable. Temperature is 37 C (98.6 F), blood pressure is 116/66 mm Hg, pulse is 80/min, and respirations are 14/min. Physical examination shows mild tenderness to deep palpation in the lumbosacral area without overlying warmth or erythema. The pain is reproducible with lumbar extension; lumbar flexion is painless. The straight-leg raising test is normal bilaterally, and gait is normal. Plain x-ray is shown in the exhibit. Which of the following is the most likely cause of this patient's condition?
Spondylolisthesis | |
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This patient with progressive low back pain has an x-ray showing anterior displacement of the L4 vertebral body relative to the L5 vertebral body, consistent with spondylolisthesis. Spondylolisthesis develops in patients who have bilateral defects/fractures of the pars interarticularis (ie, bilateral spondylolysis), which typically arise due to overuse injury. Athletes with repetitive back extension and rotation (eg, ballet dancers) are at greatest risk.
Patients with spondylolisthesis commonly have low back pain that can be reproduced with extension of the spine, which loads the fracture site. As the anterior slippage progresses, the shifted vertebral body (eg, L4 in this patient, or more commonly L5) may also impinge on the spinal cord and cause radiculopathy. On examination, there may be tenderness with deep palpation that reaches past the spinous process to the fracture site. In patients with more advanced spondylolisthesis, examination may show a palpable step-off at the area of vertebral displacement.
Lateral x-rays of the lumbar spine are used to confirm the diagnosis and determine the degree of vertebral displacement. Most patients can be treated with simple analgesics and activity modification, including cessation of the inciting sport, often for 90 days.
(Choice A) Apophysitis, inflammation of the spinous processes and supporting structures, is an overuse injury that can mimic spondylolysis and cause pain on lumbar extension. However, tenderness occurs with superficial (vs deep) palpation because of the spinous processes' superficial location. X-ray does not reveal vertebral body displacement.
(Choice C) Inflammatory spondyloarthropathy (ie, ankylosing spondylitis) can cause low back pain. However, decreased spinal motion is more common than isolated, painful (but preserved) extension, and x-ray reveals sacroiliitis and bridging syndesmophytes rather than anterior displacement.
(Choice D) Ligamentum flavum hypertrophy can lead to lumbar spinal stenosis, which can cause pain (typically radicular) that worsens on extension. However, it more commonly occurs in older adults with associated spondylosis (degeneration), and x-ray does not reveal vertebral slippage.
(Choice E) Rupture of the anulus fibrosus (leading to disc herniation) occasionally occurs in adolescent athletes. However, the associated pain typically worsens with flexion rather than extension. In addition, the straight-leg raising test is frequently positive.
Educational objective:
Spondylolisthesis is the anterior slippage of one vertebral body over another due to bilateral defects of the pars interarticularis (spondylolysis). The classic presentation is an adolescent athlete who performs repetitive back extension and rotation and then develops low back pain exacerbated by lumbar extension.