Mansfield J T., Wroten Michael
Georgetown Medstar NRH
Medstar Georgetown University
Pars interarticularis defect (otherwise referred to as spondylolysis) represents a common cause of axial back pain in adolescents, especially in the case of young athletes. The pars interarticularis (pars) lies between the superior and inferior articular process bilaterally at each vertebral level. Anatomically, one can describe the pars as the region between two, one superior and one inferior, zygapophyseal joints. The definition of pars interarticularis defect is a unilateral or bilateral overuse or fatigue stress fracture involving the pars interarticularis of the posterior vertebral arch. This injury occurs almost exclusively in the lower lumbar region, most often at L5 . Though history can be suggestive, especially in the case of young athletes involved in higher-risk sport (see below), diagnosis is made radiographically by the presence of fracture through the pars interarticularis. In cases of bilateral pars interarticularis defects, there is the potential for anterior or posterior spondylolisthesis (the slipping of one vertebral body relative to the adjacent segment). Spondylolisthesis can be graded based upon the percent degree of displacement of one vertebral body compared to the other. Grading of spondylolisthesis is included below in “staging.” Two common clinical presentations of a pars defect include the imaging of an asymptomatic adolescent or adult in whom there is the incidental discovery of a pars defect. The second common presentation is an adolescent athlete involved in a sport requiring repetitive lumbar loading in extension and rotation, presenting with acute or insidious onset low back pain that is aggravated by continued lumbar loading. Although this history is typical, there is a broad differential diagnosis that might explain these symptoms. As such, the diagnosis of a pars interarticularis defect confirmation is only with radiographic support. Depending on the time of presentation and degree of injury, most cases of pars defects respond well to conservative treatment and relative rest from sport.
椎弓峡部裂（也称为脊柱崩裂）是青少年轴向背痛的常见原因，尤其是年轻运动员。双侧椎弓峡部位于每个椎体水平的上、下关节突之间。从解剖学角度来看，椎弓峡部可描述为两个关节突关节（一个上位和一个下位）之间的区域。椎弓峡部裂的定义是涉及后椎弓的椎弓峡部的单侧或双侧过度使用或疲劳应力性骨折。这种损伤几乎只发生在腰椎下部区域，最常见于L5。尽管病史可能具有提示性，特别是对于从事高风险运动的年轻运动员（见下文），但通过椎弓峡部骨折的影像学表现进行诊断。在双侧椎弓峡部裂的情况下，存在椎体向前或向后滑脱（一个椎体相对于相邻节段的滑动）的可能性。椎体滑脱可根据一个椎体相对于另一个椎体的位移百分比进行分级。椎体滑脱的分级在下文“分期”中列出。椎弓峡部裂的两种常见临床表现包括：一是在无症状的青少年或成年人影像学检查中偶然发现椎弓峡部裂；二是参与需要反复进行腰椎伸展和旋转负荷运动的青少年运动员，出现急性或隐匿性发作的下背痛，持续的腰椎负荷会加重疼痛。虽然这种病史很典型，但有广泛的鉴别诊断可能解释这些症状。因此，椎弓峡部裂的确诊仅依靠影像学支持。根据就诊时间和损伤程度，大多数椎弓峡部裂病例对保守治疗和相对停止运动反应良好。
