What is the pathogenesis of pars interarticularis injuries?

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

The pathogenesis of pars interarticularis injuries is likely multifactorial. This "pincer theory" hypothesizes that the inferior articular process of the superiorly adjacent vertebrae and the superior articular process of the inferiorly adjacent vertebrae act as wedges and create a shear force at the pars. For example, at the L5 pars, the inferior articular process of L4 and the superior articular process of S1 would create a shear force at the L5 pars during spinal extension. [21] Two studies assessing the intrafacet distance in the lumbar spine suggest that insufficient caudal increase in lumbar interfacet spacing could be another predisposing risk factor for this condition. [22, 23]


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