Bony landmarks in the sacral region: the posterior superior iliac spine and the second dorsal sacral foramina: a potential guide for sonography

PurposeIdentification of the second dorsal sacral foramen (S2F) by sonographic imaging is a possible first step in localising the branches of the dorsal sacral rami. The aim of this investigation is to develop an imaging approach to assist the rapid identification of S2F using a well-known regional landmark, the posterior superior iliac spine (PSIS).MethodsTwenty-seven skeletal specimens were digitally imaged. Repeated measurements were undertaken of the angle and distance (D1) between PSIS and S2F, maximum width of S2F (D2), interforaminal distance between contralateral S2F (D3), distance between S1F and S2F (D4), and distance between S2F and S3F (D5). Sonographically guided needle placement was further undertaken to validate these osseous measurements in five intact cadavers.ResultsIn skeletal material, repeated measurements indicated high intraclass correlation coefficients. No statistically significant difference existed in any measure between sides. Combined measurements indicated that S2F was located 46.4 ± 14.9° from the PSIS in both sexes, with a statistical trend toward a greater angle in females. D1 had a mean value 2.2 ± 0.62 cm but was significantly shorter in females. The mean values of D2 and D3 were 0.75 ± 0.18 cm and 2.98 ± 0.27 cm, respectively, with no significant difference between sexes. The mean value of D4 was 1.42 ± 0.27 cm with a statistical trend toward a slightly smaller value in females. The mean value for D5 was 1.28 ± 0.15 cm. Sonographically guided needle placement in cadavers tended to validate these osseous measurements.ConclusionsS2F has a mean maximum width of 0.76 cm and lies approximately 2–3 cm from the PSIS, 45° inferior to the horizontal. The medial left and right borders of S2F are approximately 3 cm apart. The upper three ipsilateral dorsal sacral foramina are 1–1.5 cm apart. These measurements may be useful for sonographers imaging the dorsal sacral region and eventually, for the potential identification of neurovascular branches of the dorsal sacral rami.

[1]  J. Berthelot,et al.  Origine ligamentaire de certaines douleurs sacro-iliaques (concept de sacro-iliaque lato sensu) , 2009 .

[2]  M. Asher,et al.  Anthropometric studies of the human sacrum relating to dorsal transsacral implant designs. , 1986, Clinical orthopaedics and related research.

[3]  H. Nicholson,et al.  Branch blockade of the dorsal sacral rami. , 2010, Pain medicine.

[4]  K. Saladin.  Anatomy & Physiology: The Unity of Form and Function , 1997 .

[5]  J. Braun,et al.  Computed tomography guided corticosteroid injection of the sacroiliac joint in patients with spondyloarthropathy with sacroiliitis: clinical outcome and followup by dynamic magnetic resonance imaging. , 1996, The Journal of rheumatology.

[6]  D. Nosske,et al.  Effective doses to members of the public from the diagnostic application of ionizing radiation in Germany , 1997, European Radiology.

[7]  Peter Sögner,et al.  Feasibility of ultrasound-guided sacroiliac joint injection considering sonoanatomic landmarks at two different levels in cadavers and patients. , 2008, Arthritis and rheumatism.

[8]  Steven P. Cohen,et al.  Randomized Placebo-controlled Study Evaluating Lateral Branch Radiofrequency Denervation for Sacroiliac Joint Pain , 2008, Anesthesiology.

[9]  H. Nicholson,et al.  The long posterior sacroiliac ligament: a histological study of morphological relations in the posterior sacroiliac region. , 2009, Joint, bone, spine : revue du rhumatisme.

[10]  G. Fanelli,et al.  Ultrasound and peripheral blocks for acute and chronic pain: A review , 2009 .

[11]  F. Willard,et al.  Sensory Stimulation-Guided Sacroiliac Joint Radiofrequency Neurotomy: Technique Based on Neuroanatomy of the Dorsal Sacral Plexus , 2003, Spine.

[12]  C. O’Haire,et al.  Inter-examiner and intra-examiner agreement for assessing sacroiliac anatomical landmarks using palpation and observation: pilot study. , 2000, Manual therapy.

[13]  Young Jin Ko,et al.  Interexaminer reliability and accuracy of posterior superior iliac spine and iliac crest palpation for spinal level estimations. , 2007, Journal of manipulative and physiological therapeutics.

[14]  Bruce Elliot Hirsch,et al.  Gray’s Anatomy: The Anatomical Basis of Clinical Practice , 2009 .

[15]  P. Pynsent,et al.  Which spinal levels are identified by palpation of the iliac crests and the posterior superior iliac spines? , 2007, Journal of anatomy.

[16]  W. Kane,et al.  Simplified aspiration or injection technique for the sacro-iliac joint. , 1982, The Journal of bone and joint surgery. American volume.

[17]  J. R. Landis,et al.  The measurement of observer agreement for categorical data. , 1977, Biometrics.

[18]  Cornelius Rosse,et al.  Hollinshead's Textbook of Anatomy , 1997 .

[19]  N. Bogduk,et al.  The ability of multi-site, multi-depth sacral lateral branch blocks to anesthetize the sacroiliac joint complex. , 2009, Pain medicine.

[20]  J. Brismée,et al.  Comparing the anatomical consistency of the posterior superior iliac spine to the iliac crest as reference landmarks for the lumbopelvic spine: A retrospective radiological study , 2007, Clinical anatomy.

[21]  S. Muhlner.  Review article: radiofrequency neurotomy for the treatment of sacroiliac joint syndrome , 2009, Current reviews in musculoskeletal medicine.