Related Experiment Video
Updated: May 16, 2025

C-arm-Free Simultaneous OLIF51 and Percutaneous Pedicle Screw Fixation in a Single Lateral Position
Published on: September 16, 2022
Lumbosacral anatomy is unique in pediatric spondylolysis
Ryan A Finkel1, Nakul Narendran2, Daniel Farivar2
1Cedars-Sinai Medical Center, Department of Spine Surgery, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA. Ryan.finkel@cshs.org.
Purpose:
To determine whether patients with L5 spondylolysis have different lumbosacral anatomy compared to patients without L5 spondylolysis.
Methods:
Computed tomography (CT) scans of pediatric patients with isolated L5 spondylolysis were identified and matched 1:4 (age, sex, BMI) to patients without spondylolysis. Sagittal parameters assessed included sacral slope angle, sacral table angle, L4-S1 and L5-S1 Cobb angles, the horizontal angle of the L5 pars interarticularis, the distances between the L4 inferior articular process (IAP) and the S1 superior articular process (SAP) and their respective individual distances to the L5 pars. Coronal parameters assessed included the percent subluxation of L4 IAP below the facet joint.
Results:
1084 CT scans were reviewed. 32 patients with isolated L5 spondylolysis were identified and matched to 122 patients without spondylolysis. The horizontal angle of the L5 pars was greater in spondylolysis patients (142.5 ± 10.2 vs. 119.9 ± 5.9, p < 0.05). There was less distance (mm) between L4 IAP and S1 SAP (11.3 ± 3.9 vs. 14.7 ± 2.9, p < 0.05) and less distance (mm) from both L4 IAP (2.6 ± 1.7 vs. 5.4 ± 2.2, p < 0.05) and S1 SAP (0.7 ± 0.4 vs. 1.5 ± 0.7, p < 0.05), respectively, to the L5 pars in the spondylolysis group. Pearson's analyses revealed that a larger horizontal angle of the L5 pars was strongly associated with spondylolysis (0.59).
Conclusion:
Pediatric patients with L5 spondylolysis have a significantly more horizontal L5 pars that is closer to both the L4 IAP and S1 SAP.
Related Concept Videos
Vertebral Column: Regions and Curvature
Regions of the Vertebral Column
In an adult, the spine is subdivided into five regions: the cervical, the thoracic, the lumbar, the sacral, and the coccygeal region. The spine initially develops as a series of 33 vertebrae; after 20 years of age, the nine bones in the sacral region, five sacral, and four coccygeal bones fuse to form...
General Structure of a Vertebra
Spinal Nerves: Plexus II
The Lumbar Plexus
The lumbar plexus is situated within the lumbar region of the back and is primarily formed by the first four lumbar spinal nerves (L1 to L4). This plexus extends its branches into several nerves, including the...
Spinal Cord: Gross Anatomy
Spinal Nerves: Anatomy
There are 31 bilateral pairs of spinal nerves, each emerging from the spinal cord through the intervertebral foramina—openings between adjacent vertebrae. These nerves are...

