Background: The sacroiliac joint (SIJ) is a major source of pain in patients with chronic low
back pain. Radiofrequency ablation (RFA) of the lateral branches of the dorsal sacral rami that
supply the joint is a treatment option gaining considerable attention. However, the position of
the lateral branches (commonly targeted with RFA) is variable and the segmental innervation to
the SIJ is not well understood.
Objectives: Our objective was to clarify the lateral branches’ innervation of the SIJ and their
specific locations in relation to the dorsal sacral foramina, which are the standard RFA landmark.
Methods: Dissections and photography of the L5 to S4 sacral dorsal rami were performed on
12 hemipelves from 9 donated cadaveric specimens.
Results: There was a broad range of exit points from the dorsal sacral foramina: ranging from
12:00 – 6:00 position on the right side and 6:00 – 12:00 on the left positions. Nine of 12 of the
hemipelves showed anastomosing branches from L5 dorsal rami to the S1 lateral plexus.
Limitations: The limitations of this study include the use of a posterior approach to the pelvic
dissection only, thus discounting any possible nerve contribution to the anterior aspect of the SIJ,
as well as the possible destruction of some L5 or sacral dorsal rami branches with the removal of
the ligaments and muscles of the low back.
Conclusion: Widespread variability of lateral branch exit points from the dorsal sacral foramen
and possible contributions from L5 dorsal rami and superior gluteal nerve were disclosed by
the current study. Hence, SIJ RFA treatment approaches need to incorporate techniques which
address the diverse SIJ innervation.
Key words: Sacroiliac joint pain, radiofrequency ablation, dorsal sacral rami, low back pain
The Anatomy of the Lateral Branches of
the Sacral Dorsal Rami: Implications for
Radiofrequency Ablation