Ahmed Mohamed ElrahmanyAlexandria University, Egypt
Title: The safe entry zones to lumbar disc through transpoas approach (cadaveric study)
The minimally invasive lateral retroperitoneal transpsoas approach is a recent technique developed to avoid complications associated with traditional or minimally invasive anterior or posterior approaches to the lumbar spine. This technique provides a small incision that avoids significant abdominal muscle injury and lateral access to the disc space from L1-L2 to L4-L5.
Purpose: To define a safe entry zone in the psoas muscle to prevent lumbar plexus injury.
Methods: A total of 30 cadavers were used in this study where each cadaver was dissected from both sides. Each cadaver was placed in lateral decubitus and a skin incision in the midaxillary line from the last rib to iliac crest was made. Then, the peritoneum was dissected, psoas muscle was exposed, and nerve roots were identified and reported at each disc space from L1-L2 to L4-L5. The safe entry zone was defined by the absence of crossing of a lumbar plexus branch.
Results: Each disc space was divided into four zones: zone 1, the posterior quadrant; zone 2, the middle anterior quadrant; zone 3, the middle posterior quadrant; zone 4, the posterior quadrant. The safe working zone includes zones 2 and 3 at level L1-L2, zone 3 at level L2-L3, zone 3 at level L3-L4, and zone 2 at level L4-L5. There was no variance observed between either side regarding the relationships between the lumbar plexus and the intervertebral disc.
Conclusion: Knowledge of the anatomy of lumbar plexus roots in psoas muscle is mandatory to prevent injury to lumbar plexus roots during entry of dilator through psoas muscle. This anatomical study suggests that there are certain safe zones at the lumbar disc spaces that allow passage of dilator inside psoas muscle to reduce direct nerve injury of the lumbar plexus.
Ahmed Elrahmany worked as neurosurgical resident in Alexandria University for 5 years from 2015 to 2020. He took master degree in neurosurgery in 2020. Now he is registered in the doctoral program in Alexandria University. Also, he is head of the neurosurgical department in Borg Elarab General hospital.