What is a pars interarticularis injury?

Updated: Jan 22, 2019
  • Author: Gerard A Malanga, MD; Chief Editor: Craig C Young, MD  more...
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Answer

Lumbar spondylolysis, a unilateral or bilateral stress fracture of the narrow bridge between the upper and lower pars interarticularis, is a common cause of low back pain (LBP) in adolescent athletes. [1]  The lifetime prevalence of LBP in those aged 11-17 years has been reported to be as high as 30.4% among adolescents participating in sports. [2]  Although a variety of disorders are likely responsible for these cases, lumbar spondylolysis must be considered in the differential diagnosis of LBP in this population.

Lumbar spondylolysis is a radiographic finding that is believed to develop, in most cases, during early childhood. Typically, it is not associated with any clinical symptomatology of significance, except in a particular subset of patients who are young and adolescent athletes participating in sports that involve repetitive spinal motion, especially lumbar flexion/extension, and to a lesser degree, rotation.

Athletes who are involved in gymnastics, diving, weight lifting, wrestling, rowing, figure skating, dancing, volleyball, soccer, tennis, and football have been found to have a higher incidence of spondylolysis. [3]  The pars interarticularis defect is believed by most authors to represent a fatigue fracture caused by repetitive loading and unloading of this region of the vertebrae from physical activity. The natural history of the fracture appears to be relatively benign, and in most cases, there is no significant progression of the pars defect.

See Common Pediatric Sports and Recreational Injuries, a Critical Images slideshow, to help recognize some of the more common injuries and conditions associated with pediatric recreational activities.

Spondylolysis can persist in some cases to become spondylolisthesis. [4]  Spondylolisthesis occurs when one vertebra slips forward in relation to an adjacent vertebra, usually in the lowest lumbar vertebral segment (L5). As a result, the L5 vertebral body slips forward on the S1 vertebral body. This also commonly occurs at the L4 and L5 levels. Spondylolisthesis is almost never due to trauma; however, it is usually discovered after a trauma or prolonged episode of back pain in an athlete prompts radiographic studies.

Most patients with either spondylolysis or spondylolisthesis have excellent clinical outcomes with conservative measures, and surgical intervention rarely is rarely necessary. [1, 4, 5]  In selected cases, those patients unresponsive to nonoperative measures may benefit from surgical management. The approach to surgical management is dictated by the age of the patient and the degree of associated spondylolisthesis. [6]

This article focuses on isthmic spondylolysis as an independent entity from spondylolisthesis and its relationship to athletes, as this type of spondylolysis is a primary focus of concern in athletic adolescents.

For patient education resources, see the patient education articles Back Pain and Slipped Disk.


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