Pars interarticularis of vertebral arch
Pars interarticularis arcus vertebrae
- Latin synonym: Isthmus arcus vertebralis
- Synonym: Isthmus of vertebral arch
Definition
The pars interarticularis of vertebral arch (isthmus) is the specific part of the vertebral arch located between the superior and inferior articular processes of a vertebra. The pars interarticularis is often referred to as the "isthmus" and is particularly significant in the context of spinal pathologies such as spondylolysis, which is a stress fracture of this region.
In the cervical spine, particularly the C2 vertebra, the pars interarticularis is defined as the narrower portion between the superior and inferior facets.[1] This anatomical feature is crucial for surgical procedures such as transpedicular screw fixation, where precise knowledge of the pars interarticularis is necessary to avoid complications.[1-2]
In the lumbar spine, the pars interarticularis is similarly located between the superior and inferior articular processes and is subject to stress fractures, especially in athletes due to repetitive loading and shearing forces.[3] The development and ossification of the pars interarticularis begin in fetal life and continue into early childhood, with variations in trabeculation and cortication that can predispose to stress fractures.[4]
References
1.The Location of the Pedicle and Pars Interarticularis in the Axis.Ebraheim NA, Fow J, Xu R, Yeasting RA.Spine. 2001;26(4):E34-7. doi:10.1097/00007632-200102150-00002.
2.Asymmetry of the C2 Pars Interarticularis: A Clinical Anatomical Study With Relevance to Screw Placement.Huang B, Khan PA, Iwanaga J, et al.Surgical and Radiologic Anatomy : SRA. 2022;44(3):423-429. doi:10.1007/s00276-022-02901-2.
3.Pars Interarticularis Injury in Elite Athletes - The Role of Imaging in Diagnosis and Management.Cheung KK, Dhawan RT, Wilson LF, Peirce NS, Rajeswaran G.European Journal of Radiology. 2018;108:28-42. doi:10.1016/j.ejrad.2018.08.029.
4.Histomorphic Analysis of the Development of the Pars Interarticularis and Its Association With Isthmic Spondylolysis.Sagi HC, Jarvis JG, Uhthoff HK.Spine. 1998;23(15):1635-9; discussion 1640. doi:10.1097/00007632-199808010-00002.
